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ISTUDY

Ellis and Calne’s Lecture Notes in GENERAL SURGERY

Christopher Watson

Justin Davies 14th Edition

flDD

WILEY Blackwell

Ellis and Calne’s Lecture Notes in General Surgery

Ellis and Calne’s Lecture Notes in General Surgery Edited by

Christopher Watson, MD BChir FRCS Professor of Transplantation and Honorary Consultant Surgeon Cambridge University Hospitals NHS Foundation Trust Cambridge, UK

Justin Davies, MA MChir FRCS (Gen Surg) FEBS (Coloproctology) Consultant Colorectal Surgeon Cambridge University Hospitals NHS Foundation Trust Affiliated Assistant Professor University of Cambridge Fellow in Clinical Medicine Downing College, Cambridge, UK

Fourteenth Edition

This fourteenth edition first published 2023 © 2023 John Wiley & Sons Ltd Edition History 1965, 1968, 1970, 1972, 1977, 1983, 1987, 1993, 1998, 2002, 2006, 2011, 2016 by Harold Ellis, Sir Roy Y. Calne and Christopher J. E. Watson All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.

The right of Christopher Watson, and Justin Davies to be identified as the authors of the editorial material in this work has been asserted in accordance with law.

Registered Office John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK For details of our global editorial offices, customer services, and more information about Wiley products visit us at www.wiley.com.

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Library of Congress Cataloging-in-Publication Applied for Paperback ISBN: 9781119862482 Cover Design: Wiley Cover Image: © Morsa Images/Getty Images Set in 8.5/11 pt Utopia by Straive, Pondicherry, India

Contents Author affiliations, vi

24 The surgery of obesity, (Christopher Pring), 240

Preface, viii

25 The small intestine (Justin Davies), 245

Acknowledgements, ix

26 The appendix (Ioanna G. Panagiotopoulou), 251

Abbreviations, x

27 The colon (Justin Davies), 259

About the companion website, xiv

28 The rectum and anal canal (Justin Davies), 274

1 Surgical strategy (Justin Davies), 1 2 Human factors in surgery (Peter A. Brennan), 5 3 Fluid and nutrition management (Lynsey Spillman), 12 4 Preoperative assessment (Hemantha Alawattegama), 20 5 Postoperative complications (Elizabeth Tweedle), 27 6 Acute infections (Christopher Watson), 49 7 Tumours (Christopher Watson), 55 8 Shock (Vijay Sujendran), 63 9 Trauma surgery (Jonathan Morton), 70 10 Burns (Ian Grant), 79 11 The skin and its adnexae (Amer J. Durrani), 86 12 Arterial disease (Patrick Coughlin), 101 13 The heart and thoracic aorta (David P. Jenkins), 119 14 The chest and lungs (Aman Singh Coonar), 129 15 Venous disorders of the lower limb (Manj Gohel), 140 16 The brain and meninges (Stephen Price), 147 17 Head injury (Stephen Price), 157 18 The spine (Rodney J. C. Laing), 170 19 Peripheral nerve injuries (Ian Grant), 182 20 The oral cavity (Kanwalraj Moar), 189 21 The salivary glands (Brian Fish), 203 22 The oesophagus (Peter Safranek), 208 23 The stomach and duodenum (Stavros Gourgiotis), 218

29 The acute abdomen (Constantinos Simillis), 289 30 Intestinal obstruction and paralytic ileus (Christopher Watson), 299 31 Hernia (Christopher Watson), 311 32 The liver (Raaj Kumar Praseedom), 323 33 The gallbladder and bile ducts (Anita Balakrishnan), 340 34 The pancreas (Raaj Kumar Praseedom), 351 35 The spleen (Christopher Watson), 364 36 The lymph nodes and lymphatics (Christopher Watson), 367 37 The breast (Eleftheria Kleidi), 371 38 The neck (Ekpemi Irune), 389 39 The thyroid (Brian Fish), 393 40 The parathyroids (Ekpemi Irune), 406 41 The thymus (Christopher Watson), 412 42 The adrenal glands (Vasilis Kosmoliaptsis), 414 43 The kidney and ureter (Alexandra J. Colquhoun), 425 44 The bladder (Alexandra J. Colquhoun), 444 45 The prostate (Arthur McPhee), 450 46 The male urethra (Arthur McPhee), 459 47 The penis (Arthur McPhee), 462 48 The testis and scrotum (Alexandra J. Colquhoun), 466 49 Transplantation surgery (Christopher Watson), 476 Index, 484

Author affiliations Hemantha Alawattegama Consultant Anaesthetist Cambridge University Hospitals NHS Foundation Trust Anita Balakrishnan Consultant HPB Surgeon Cambridge University Hospitals NHS Foundation Trust Peter A. Brennan Consultant Maxillofacial Surgeon and Honorary Professor of Surgery Portsmouth Hospitals University Trust Portsmouth Alexandra J. Colquhoun Consultant Urologist Cambridge University Hospitals NHS Foundation Trust Aman Singh Coonar Consultant Thoracic Surgeon Royal Papworth Hospital Cambridge Patrick Coughlin Leeds Vascular Institute Leeds Justin Davies Consultant Colorectal Surgeon Cambridge University Hospitals NHS Foundation Trust

Manj Gohel Consultant Vascular & Endovascular Surgeon Cambridge University Hospitals NHS Foundation Trust Honorary Senior Lecturer Imperial College London Stavros Gourgiotis Consultant Surgeon Cambridge Oesophago-­Gastric Centre Cambridge University Hospitals NHS Foundation Trust Ian Grant Consultant Plastic Surgeon Cambridge University Hospitals NHS Foundation Trust Ekpemi Irune Consultant Laryngology, Head & Neck Surgeon Cambridge University Hospitals NHS Foundation Trust David P. Jenkins Consultant Cardiothoracic Surgeon Royal Papworth Hospital Cambridge Eleftheria Kleidi Consultant Oncoplastic Breast Surgeon Cambridge University Hospitals NHS Foundation Trust

Affiliated Assistant Professor University of Cambridge

Vasilis Kosmoliaptsis Honorary Consultant Abdominal Transplant, HPB and Endocrine Surgeon

Fellow in Clinical Medicine Downing College, Cambridge

Associate Professor, Department of Surgery University of Cambridge

Amer J. Durrani Consultant Plastic & Reconstructive Surgeon Cambridge University Hospitals NHS Foundation Trust

Rodney J. C. Laing Consultant Neurosurgeon Cambridge University Hospitals NHS Foundation Trust

Brian Fish Consultant ENT/Head and Neck Surgeon Cambridge University Hospitals NHS Foundation Trust

Arthur McPhee Consultant Urologist Cambridge University Hospitals NHS Foundation Trust

Author affiliations

Kanwalraj Moar Consultant Cleft and Maxillofacial Surgeon Cambridge University Hospitals NHS Foundation Trust Jonathan Morton Consultant Colorectal Surgeon Cambridge University Hospitals NHS Foundation Trust Ioanna G. Panagiotopoulou Consultant Colorectal Surgeon Cambridge University Hospitals NHS Foundation Trust Raaj Kumar Praseedom Consultant HPB & Transplant Surgeon Cambridge University Hospitals NHS Foundation Trust Stephen Price Honorary Consultant Neurosurgeon Cambridge University Hospitals NHS Foundation Trust Christopher Pring Consultant Bariatric Surgeon St Richard’s Hospital Chichester Visiting Professor University of Surrey

vii

Peter Safranek Consultant Surgeon Cambridge Oesophago-­Gastric Centre Cambridge University Hospitals NHS Foundation Trust Constantinos Simillis Consultant Colorectal Surgeon Cambridge University Hospitals NHS Foundation Trust Lynsey Spillman Hepatology and Liver Transplant Dietitian Cambridge University Hospitals NHS Foundation Trust Vijay Sujendran Consultant Surgeon Cambridge Oesophago-­Gastric Centre Cambridge University Hospitals NHS Foundation Trust Elizabeth Tweedle Consultant Colorectal Surgeon Cambridge University Hospitals NHS Foundation Trust Christopher Watson Professor of Transplantation and Honorary Consultant Surgeon Cambridge University Hospitals NHS Foundation Trust

Preface Many medical students will have effectively written their own textbook at the end of their clinical course – a digest of the lectures and tutorials assiduously attended and of the textbooks meticulously read.

Unfortunately, students may approach the qualifying examinations burdened by the thought of many pages of excellent and exhaustive textbooks wherein lies the wisdom required of them by the examiners. Although the Internet is increasingly used as a source of information, we believe that there is still a serious need for a book that briefly sets out the important facts in General Surgery that are classified, analysed and, as far as possible, rationalized for the revision student.

These lecture notes represent such a text; they are in no way a substitute for the standard textbooks, but they do draw together, in a logical way, the fundamentals of General Surgery and its subspecialties. As such we hope it will also be of use to the junior surgeon.

We wish to point the reader to the electronic resource accompanying the text, including case studies, radiographs and histology slides illustrating ­common conditions mentioned in the text, as well as a quiz to test the reader’s knowledge.

The first edition of Lecture Notes in General Surgery was written by Harold Ellis and Sir Roy Calne and published in 1965. This is the first edition without their involvement, and we acknowledge their huge contribution to surgery and its teaching. Surgery has changed enormously since the days of that first edition, and each subsequent edition has tried to keep pace with surgical practice. Never has the pace of change been so great as it is today. The biggest changes have been seen in the development of ­specialist services, at the expense of the generalist, and the development of multidisciplinary teams to optimize management. Recognizing this, previous editions have relied heavily on colleagues from other specialties to keep chapters updated and relevant. For this edition we have taken this further, and each chapter now has a nominated expert author – who, for some chapters, has updated previous content; and, for others, has written completely new content – to ensure relevance for today’s student.

Christopher Watson Justin Davies

Acknowledgements We are grateful to our colleagues – senior and junior doctors, and students – who have read and critiqued this text during its production, and to many readers and reviewers for their constructive criticisms. We are indebted to those colleagues in years gone by, too numerous to mention here, who have developed

the text upon which the new chapter experts have built. We would also like to acknowledge the continued help give by the staff at Wiley for seeing this ­project through to publication, in particular James Watson, Catriona King, Mandy Collison, Ella Elliott, and Indirakumari Siva.

Abbreviations ABPI

ankle brachial pressure index

CAPOX

capecitabine and oxaliplatin

ABG

arterial blood gas

CAR

chimeric antigen receptor

ABLS

Advanced Burns Life Support

CaSR

calcium sensing receptor

ACE

angiotensin-­converting enzyme

CEA

carcinoembryonic antigen

ACTH

adrenocorticotrophic hormone

CEAP

ADH

antidiuretic hormone

Clinical, Etiological, Anatomical and Pathophysiological

ADT

androgen deprivation therapy

CHRPE

AFP

α-­fetoprotein

congenital hypertrophy of the retinal pigment epithelium

AIs

aromatase inhibitors

CMV

cytomegalovirus

AIDS

acquired immune deficiency syndrome

CNS

central nervous system

AIN

anal intraepithelial neoplasia

COPD

chronic obstructive pulmonary disease

AJCC

American Joint Committee on Cancer

CPAP

continuous positive airways pressure

ALK

anaplastic lymphoma kinase

CPE

ALP

alkaline phosphatase

carbapenemase-­producing enterobacteriaceae

ALT

alanine transaminase

CPPS

chronic pelvic pain syndrome

ANC

axillary node clearance

CRE

carbopenem-­resistant enterobacteriaceae

ANS

axillary node sampling

CRP

C-­reactive protein

ANUG

acute necrotizing ulcerative gingivitis

CSF

cerebrospinal fluid

APFC

acute peripancreatic fluid collection

CT

computed tomography

APACHE

Acute Physiology and Chronic Health Evaluation

CTLA4

cytotoxic lymphocyte–associated antigen 4

CTPA

APTT

activated partial thromboplastin time

computed tomographic pulmonary angiography

APUD

amine precursor uptake and decarboxylation

CVP

central venous pressure

CXR

chest X-­ray

ASA

American Society of Anesthesiologists

DBD

donation after brain-­stem death

ASD

atrial septal defect

DCD

donation after circulatory death

ASIA

American Spinal Injury Association

DCIS

ductal carcinoma in situ

aspartate transaminase

DCS

damage control surgery

ATN

acute tubular necrosis

DDAVP

deamino-­d-­arginine vasopressin

ATLS

Advanced Trauma Life Support

DHCA

deep hypothermic circulatory arrest

AXR

abdominal X-­ray

DIC

disseminated intravascular coagultion

β-­HCG

β-­human chorionic gonadotrophin

DIOS

distal intestinal obstruction syndrome

BCG

bacille Calmette–Guérin

DMSA

dimercaptosuccinic acid

BCS

breast conserving surgery

DOPA

dihydroxyphenyl alanine

BMI

body mass index

DST

dexamethasone suppression test

BPH

benign prostatic hyperplasia

DTC

differentiated thyroid cancer

CABG

coronary artery bypass graft

DTPA

diethylene triamine penta-­acetic acid

AST

Abbreviations

xi

DVT

deep venous thrombosis

GnRH

gonadotrophin-­releasing hormone

EBV

Epstein-­Barr virus

GORD

gastroesophageal reflux disease

ECG

electrocardiogram

GPA

granulomatosis with polyangiitis

ECST

European Carotid Surgery Trial

GTN

glyceryl trinitrate

EGFR

epidermal growth factor receptor

HAART

highly active antiretroviral treatment

EGC

early gastric cancer

HALO

haemorrhoidal artery ligation

EMG

electromyography

HALT

hungry, anxious/angry, late, tired

EMR

endoscopic mucosal resection

HAMN

EMSB

Emergency Management of Severe Burns

high-­grade appendiceal mucinous neoplasms

ER

oestrogen receptor

HbA1c

glycosylated haemoglobin

ERAS

Enhanced Recovery After Surgery

HCl

hydrochloric acid

ERCP

endoscopic retrograde cholangiopancreatography

HCC

hepatocellular carcinoma

HER2

human epidermal growth factor receptor 2

ESBL

extended spectrum β-­lactamase

HGD

high-­grade dysplasia

ESD

endoscopic submucosal dissection

HHT

hereditary haemorrhagic telangiectasia

ESR

erythrocyte sedimentation rate

HHV

human herpes virus

ESWL

extracorporeal shock-­wave lithotripsy

HIPEC

heated intraperitoneal chemotherapy

EUS

endoscopic or endoluminal ultrasound

HIV

human immunodeficiency virus

EVAR

Endovascular Aneurysm Repair

HLA

human leucocyte antigen

5-­FU

5-­fluorouracil

HNPCC

hereditary non-­polyposis colon cancer

FAP

familial adenomatous polyposis

HoLEP

holmium laser prostatectomy

FAST

focused abdominal sonography for trauma

HPOA

hypertrophic pulmonary osteoarthropathy

FBC

full blood count

HPV

human papilloma virus

FDG

fluorodeoxyglucose

HQIP

FEV1

forced expiratory volume in 1 second

Healthcare Quality Improvement Partnership

FFP

fresh frozen plasma

HRT

hormone replacement therapy

faecal immunochemical test

HSV

herpes simplex virus

FNAC

fine-­needle aspiration cytology

HTIG

human tetanus immunoglobulin

FOLFOX

folinic acid and oxaliplatin

IBD-­U

inflammatory bowel disease unclassified

FSH

follicle-­stimulating hormone

ICC

interstitial cell of Cajal

GABA

γ-­aminobutyric acid

ICP

intracranial pressure

gastrointestinal autonomic nervous tumour

ICSI

intracytoplasmic sperm injection

Glasgow Coma Score

ICU

intensive care unit

GEP-­NETs gastroenteropancreatic neuroendocrine tumours

IFN

interferon

IMA

inferior mesenteric artery

GFR

glomerular filtration rate

IMV

inferior mesenteric vein

GGT

γ-­glutamyl transferase

INR

International normalized ratio

GI

gastrointestinal

IPMN

intraductal papillary mucinous neoplasm

GIM

gastrointestinal metaplasia

IPSS

International prostate symptom score

GIST

gastrointestinal stromal tumour

ITU

intensive therapy unit

GLA

γ-­linolenic acid

IVC

inferior vena cava

GOJ

gastro-­oesophageal junction

IVF

in vitro fertilization

FIT

GANT GCS

xii

Abbreviations

IVU

intravenous urogram

NHS

National Health Service

JVP

jugular venous pressure

NICE

KSHV

Kaposi sarcoma herpes virus

National Institute of Health and Care Excellence

KUB

kidneys, ureters and bladder

NG

nasogastric

LAD

left anterior descending artery

NOACs

novel oral anticoagulants

low-­grade appendiceal mucinous neoplasms

NPI

Nottingham Prognostic Index

NSAIDs

non-­steroidal anti-­inflammatory drugs

LCIS

lobular carcinoma in situ

NSCLC

non-­small cell lung cancer

LDH

lactate dehydrogenase

NSGCT

non-­seminomatous germ cell tumour

LGD

low-­grade dysplasia

NST

no special type

LHRH

luteinizing hormone-­releasing hormone

OCP

oral contraceptive pill

LIF

left iliac fossa

OPG

orthopantomogram

LiDCO

transpulmonary lithium dilution cardiac output

OPSI

overwhelming post-­splenectomy infection

PAC

plasma aldosterone concentration

LMWH

low-­molecular-­weight heparin

PBC

primary biliary cholangitis

LUTS

lower urinary tract symptoms

PCI

percutaneous coronary intervention

MAG3

mercapto-­acetyl triglycine

MAMC

midarm muscle circumference

pcr

pathologic complete response

MCN

mucinous cystic neoplasm

PDE5

phosphodiesterase type 5

MDT

multidisciplinary team

PDGFA

platelet-­derived growth factor receptor α

MELD

model for end-­stage liver disease

PDL

programmed death ligand

MEN

multiple endocrine neoplasia

PE

pulmonary embolism

MHC

major histocompatibility complex

PEC

percutaneous endoscopic colostomy

MIBG

meta-­iodobenzylguanidine

PEG

polyethylene glycol

MIBI

methoxyisobutylisonitrile

PEG

percutaneous endoscopic gastrostomy

MOI

mechanism of injury

PET

positron emission tomography

mpMRI

multiparametric MRI

PI_RADS

prostate imaging reporting and data system

MR

magnetic resonance

PICC

peripherally inserted central catheter

MRC

Medical Research Council

PN

parenteral nutrition

MRCP

magnetic resonance cholangiopancreatography

PNET

primitive neuroectodermal tumour

POEM

per oral endoscopic myotomy

MRI

magnetic resonance imaging

POSSUM

MRSA

methicillin-­resistant Staphylococcus aureus

mTOR

mechanistic target of rapamycin

Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity

MUST

Malnutrition Universal Screening Tool (ch 3)

PPE

personal protective equipment (ch 2)

NAFLD

non-­alcoholic fatty liver disease

PPGL

Phaeochromocytoma and paraganglioma

NASCET

North American Symptomatic Carotid Endarterectomy Trial

PPP

patient, procedure and people

PR

progesterone

NCEPOD

National Confidential Enquiry into Perioperative Death

PRA

plasma renin activity

PRC

plasma renin concentration

NELA

National Emergency Laparotomy Audit

PSA

prostate-­specific antigen

NEWS

National Early Warning Score

PSC

primary sclerosing cholangitis

neuroendocrine neoplasms

PT

prothrombin time

LAMN

NEN

Abbreviations

xiii

PTA

percutaneous transluminal angioplasty

TCC

transitional cell carcinoma

PTC

percutaneous transhepatic cholangiography

TED

thromboembolism deterrent

TEVAR

thoracic endovascular aortic repair

PTCA

percutaneous transluminal coronary angioplasty

TIA

transient ischaemic attack

TIPS

transjugular intrahepatic portosystemic shunt

PTFE

polytetrafluoroethylene

PTH

parathormone

TNF

tumour necrosis factor

PUJ

pelviureteric junction

TNM

tumour node metastasis

PV

portal vein

TOE

transoesophageal echocardiography

RIF

right iliac fossa

TPA

tissue plasminogen activator

SAH

subarachnoid haemorrhage

TPN

total parenteral nutrition

SBP

spontaneous bacterial peritonitis

TRAM

transverse rectus abdominis myocutaneous

SCLC

small-­cell lung cancer

TRH

thyrotrophin-­releasing hormone

SDHX

succinate dehydrogenase subunit genes

TRUS

transrectal ultrasound

SDM

shared decision-­making

TSH

thyroid-­stimulating hormone

SGA

Subjective Global Assessment

TUR

transurethral resection

SGOT

serum glutamic oxaloacetic transaminase (synonymous with AST)

UC

urothelial carcinoma

serum glutamic pyruvic transaminase (synonymous with ALT)

UC

ulcerative colitis

UFH

unfractionated heparin

UKELD

United Kingdom Model for end-­stage liver disease

UW

University of Wisconsin

VAB

vacuum-­assisted biopsy

VAC

vacuum-­assisted closure

VATS

video-­assisted thoracoscopic surgery

VAWCM

vacuum-­assisted wound closure device with mesh-­mediated fascial traction

VEGF

vascular endothelial growth factor

VEGFR-­3

vascular endothelial growth factor receptor 3

VET

venous thromboembolism

VIP

vasoactive intestinal polypeptide

VISA

vancomycin-­intermediate Staphylococcus aureus

SGPT SIADH

syndrome of inappropriate antidiuretic hormone

SLE

systemic lupus erythematosus

SLN

sentinel lymph node

SMA

superior mesenteric artery

SMV

superior mesenteric vein

SORT

Surgical Outcome Risk Tool

SSI

surgical site infection

SV

splenic vein

SVT

superficial vein thrombosis

TAD

targeted axillary dissection

TB

tuberculosis

T3

tri-­iodothyronine

T4

tetra-­iodothyronine, thyroxine

TACE

transarterial chemoembolization

VRE

vancomycin-­resistant Enterococcus

TAE

tumour embolisation

VRSA

TAP

transversus abdominus plane

Vancomycin-­resistant Staphylococcus aureus

TAVI

transaortic valve implantation

WHO

World Health Organisation

About the companion website This book is accompanied by a companion website. www.wiley.com/go/Watson/GeneralSurgery14 The website features: • Interactive multiple choice and short-answer questions • Case Studies • Extra images and photographs • Biographies

1 Surgical strategy Justin Davies Learning objectives ✓✓ To understand the principles of taking a clear history, performing an appropriate examination, presenting the findings and formulating a management plan for diagnosis and subsequent investigations and treatment. ✓✓ To understand the common nomenclature used in surgery.

The principles of assessing patients referred to a ­surgical team has changed little in recent times. These include: 1 Taking an accurate history.

2 Examination of the patient.

3 Accurate and contemporaneous documentation (written and/or electronic).

4 Constructing a differential diagnosis. Ask the ­question ‘What diagnoses would best explain this clinical picture?’

5 Special investigations. Which laboratory and imaging tests are required to confirm or refute the clinical diagnosis?

6 Management. Decide on the management of the patient, including provision of adequate analgesia. Remember that this will include reassurance, explanation, and good communication skills.

History and examination Development of clinical skills is of paramount ­importance in all aspects of medicine and surgery. In some circumstances, excessive reliance on special Ellis and Calne’s Lecture Notes in General Surgery, Fourteenth Edition.

Edited by Christopher Watson and Justin Davies. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/Watson/GeneralSurgery14

investigations and extensive imaging may be ­unnecessary. It is important to remember that the patient may be apprehensive and will often be in pain, especially when presenting as an emergency.

Attending to these issues is an especially important aspect of good clinical care.

The history The history should be an accurate reflection of what the patient has said. It is important to ask open questions such as ‘When were you last well?’ and ‘What happened next?’ rather than closed questions such as ‘Do you have chest pain?’ If you have a positive finding, it is important to explore this further with more directed questioning, for example, ‘When did it start?’ ‘What makes it better, and what makes it worse?’ ‘Where did it start and where did it go?’ ‘Did it come and go, or was it constant?’ If the symptom is characterized by bleeding, ask about what sort of blood (e.g. fresh, bright red, dark red), when it started, how much, whether there were clots, whether it was mixed in with food/faeces and whether it was associated with pain. Remember that most patients come to see a general surgeon, particularly in the emergency setting, because of abdominal pain or bleeding (Table 1.1). You will need to find out as much as you can about the presenting symptoms.

Keep in mind that the patient may have little a­ ccurate anatomical knowledge. They might say ‘my stomach

2

Surgical strategy

Table 1.1 Examples of important facts to determine in patients with pain and rectal bleeding Pain

Rectal bleeding

Exact site

Estimation of amount (often inaccurate)

Radiation

Timing of bleeding

Length of history

Colour – bright red, dark red, black

Periodicity

Accompanying symptoms – pain, vomiting (haematemesis)

Nature – constant/colicky

Associated features – fainting, shock, etc.

Severity

Blood mixed in stool, lying on surface, on toilet paper, in toilet bowl

Relieving and aggravating factors Accompanying features (e.g. jaundice, vomiting, haematuria)

hurts’, but this may be due to lower chest or periumbilical pain – it is important to ask them to point to the site of the pain. Bear in mind that they may be pointing to a site of referred pain, and a vague description such as ‘back pain’ will need further exploration and clarification as to where it is in the back – the sacrum or lumbar, thoracic or cervical spine, or possibly the loin or subscapular regions. Exploring pain outside of the abdomen is important, particularly shoulder pain. This may, for example, suggest referred pain from the diaphragm or gallbladder.

It is often useful to consider the viscera in terms of their embryology. Thus, epigastric pain is generally from foregut structures such as the stomach, duodenum, liver, gallbladder, spleen and pancreas; periumbilical pain is midgut pain from the small bowel and ascending colon, including the appendix; suprapubic pain is hindgut pain, originating in the colon, rectum and other structures of the cloaca such as the bladder,

T8,9 Small bowel Appendix Caecum Ascending colon to midtransverse Testis

Renal tract

T10

uterus and Fallopian tubes (Figure 1.1). Testicular pain may also be periumbilical, reflecting the intra-­ abdominal origin of these organs before their descent into the scrotum – this is exemplified by the child with testicular torsion who initially complains of pain in the centre of their abdomen.

The examination Remember the classic quartet in this order: 1 2 3 4

Inspection.

Palpation.

Percussion.

Auscultation.

Careful inspection is always time well spent. Inspect the patient generally, as to how they lie and breathe.

Are they tachypnoeic because of a chest infection or in response to a metabolic acidosis? Look at the

Liver Gall bladder Spleen Stomach Duodenum Pancreas Heart and aorta

T11

T12 L1

Large bowel Bladder Prostate ( ) Uterus and adnexa ( )

Figure 1.1 Location of referred pain for the abdominal organs.

Surgical strategy

patient’s hands and feel the pulse. Asking the patient to walk may be revealing in someone with claudication or in assessment of general fitness.

Only after careful inspection should palpation start.

If you are examining the abdomen in the emergency setting, it is important to ask the patient to cough. This is a surrogate test of rebound tenderness and indicates where the site of inflammation is within the peritoneal cavity. It is often helpful to examine the ‘normal’ or non-­symptomatic side first, be it the abdomen, hand, leg or breast. Look carefully at the patient’s face while you palpate, as this may provide subtle clues regarding discomfort or tenderness. If there is a lump, decide which anatomical plane it lies within. Is it in the skin, in the subcutaneous tissue, in the muscle layer or, in the case of the abdomen, in the underlying cavity? Is the lump pulsatile, expansile or mobile?

3

Documenting medical notes We practice in an era where electronic patient records are becoming more commonplace, although currently the UK still has the majority of hospitals with paper-­based medical records. The number with electronic records will continue to increase over time.

Always write or type your findings completely and accurately in a contemporaneous fashion. Start by recording the date and time of the assessment and check that you have the correct patient’s notes open. Record all the negative as well as positive findings. Avoid abbreviations where possible since they may mean different things to different people; for example, PID – you may mean pelvic inflammatory disease, but the next person might interpret it as a prolapsed intervertebral disc. Use the appropriate surgical terminology (Table 1.2).

Table 1.2 Common prefixes and suffixes used in surgery Prefix

Related organ/structure

angio-­

blood vessels

arthro-­

a joint

cardio-­

heart

cholecysto-­

gallbladder

coelio-­

peritoneal cavity

colo-­and colon-­

colon

colpo-­

vagina

cysto-­

urinary bladder

gastro-­

stomach

hepato-­

liver

hystero-­

uterus

laparo-­

peritoneal cavity

mammo-­and masto-­

breast

nephro-­

kidney

oophoro-­

ovary

orchid-­

testicle

rhino-­

nose

thoraco-­

chest

Suffix

Procedure

-­centesis

surgical puncture, often accompanied by drainage, e.g. thoracocentesis

-­desis

fusion, e.g. arthrodesis

-­ectomy

surgical removal, e.g. colectomy

-­oscopy

visual examination, usually through an endoscope, e.g. laparoscopy

-­ostomy

creating a new opening (mouth) on the surface, e.g. colostomy

-­otomy

surgical incision, e.g. laparotomy

-­pexy

surgical fixation, e.g. orchidopexy

-­plasty

to mould or reshape, e.g. angioplasty; also to replace with prosthesis, e.g. arthroplasty

-­rrhaphy

surgically repair or reinforce, e.g. herniorrhaphy

4

Surgical strategy

Irregular enlarged liver edge

Previous perforated duodenal ulcer repair

Kidney transplant Tender ++

Bowel sounds normal PR: No tenderness, no mass Normal colour stool

Illustrate your examination unambiguously with simple drawings when possible – use anatomical reference points and measure the diameter of any lumps accurately. When drawing abdominal findings, use a hexagonal representation (Figure 1.2). A continuous line implies an edge; shading can represent an area of tenderness or the site where pain is experienced. If you can feel all around a lump, draw a line to indicate this; if you can feel only the upper margin, show only this. Annotate the drawings with your findings (Figure 1.2). At the end of your notes, write a single paragraph summary and make a diagnosis or record a differential diagnosis. Outline a management plan and state what investigations should be done, indicating those which you have already arranged. Sign your

Figure 1.2 Example of how to record abdominal examination findings.

notes and print your name, position and contact details, with the time and date recorded.

Case presentation The purpose of presenting a case is to convey to your colleagues the salient clinical features, diagnosis or differential diagnosis, management, and investigations of the patient. The presentation should ideally be succinct and to the point, containing important positive and negative findings. At the end of a case presentation, the listening team should have an excellent word picture of the patient and their problems, what needs to be monitored and what plans you have for management.

2 Human factors in surgery Peter A. Brennan Learning objectives ✓✓ To understand the factors that can affect safe surgical practice. ✓✓ To know what measures to take to mitigate risks in surgery.

What are human factors?

There are many definitions of this term, but a simple one to remember is how we interact with each other (in teams), the systems in which we work, our variability and the factors that affect our performance and those of team members. In healthcare, human factors application can lead to improved patient safety, better team working and staff morale. Important elements of human factors also include situational awareness, effective team working, safe and effective communication, and good leadership. Furthermore, by recognizing how both physical and mental performance deteriorate over time helps to consolidate their importance.

As humans, we regularly make mistakes, with an average of five to seven simple errors affecting each of us every day. These might be something simple such as forgetting a wallet or a mobile phone when leaving for work because of a distraction. While these errors or omissions might be annoying, error in healthcare is a cause of significant patient harm and mortality. We can never completely eliminate error, and as the above-­mentioned examples demonstrate, it is a familiar part of everyday life. The term ‘never event’ has been coined to describe occurrences that should not occur in a healthcare setting and includes wrong

Ellis and Calne’s Lecture Notes in General Surgery, Fourteenth Edition.

Edited by Christopher Watson and Justin Davies. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/Watson/GeneralSurgery14

site surgery, retained instruments and swabs, and incorrect naso-­gastric tube placement. A ‘never event’ is somewhat of a misnomer as error can never be completely eliminated, but the chances of error occurring can be minimized.

The Roman Philosopher Cicero (106–43 BC) wrote ‘anyone is liable to err (make a mistake), but only a fool persists in error’. Learning from mistakes and sharing lessons widely with others is one of the most important elements to improving patient safety across healthcare.

Error in healthcare The interplay of human error and human factors in clinical incidents (including factors that have their origins in hospitals where we work) is becoming more widely understood. It is often more than one issue (or layer) that leads to error, and this is readily demonstrated by the well-­known Swiss cheese model (Figure 2.1).

Often, factors are multifactorial and take place simultaneously – recognizing this fact is the first step to understanding human factors in surgery. These multifactorial issues include ones that affect us as individuals, such as tiredness, repetition, stress, the effects of distraction and multi-­tasking. Other factors can occur as part of team working, and these include poor communication or leadership, loss of situational awareness, and steep (or flat) authority gradients.

The introduction of the World Health Organisation

6

Human factors in surgery

Latent failures Latent/active failures Unsafe supervision

Organisational influences

Preconditions to unsafe acts Active failures Unsafe acts

Failed or absent defenses

Figure 2.1 The Swiss cheese model of human error. Each slice can act as a barrier.

(WHO) surgical checklist (Figure 2.2) has improved attitudes towards pre-­surgery briefing and patient safety, and the benefits of recognizing and applying these human factors principles in surgery are well known.

One in 20 hospital admissions has some form of error, and of these one in 20 are serious (i.e. one in 4,000 admissions). The operating theatre is known to be one of the most potentially error-­prone places in the hospital as a result of high patient turnover, site-­ specific treatments, many heterogeneous surgical procedures, staff limitations and unfamiliar teams.

What are the different types of error and failure?

The Human Factors Analysis and Classification System (HFACS) categorizes failure across four broad domains: 1 2 3 4

Organizational influences.

Unsafe supervision.

Preconditions to unsafe acts.

Unsafe acts.

All four domains can be applied to the Swiss cheese model (Figure 2.1). Failures at each level may be active (decisions, actions or attitudes by individuals or surgical teams) or latent (results of deficiencies with the ­hospital or management team). Examples of failures in the clinical setting that can have their origin in the employing organization include pressures of overbooked clinics or

operating theatre sessions, meeting clinical and hospital targets and prolonged working hours without breaks.

Medical error may, therefore, begin to develop well before the actual event itself (such as wrong site surgery) as a result of institutional failure.

What human factors in surgery should we be thinking about?

Table 2.1 summarizes some important human factors that can contribute to and ultimately lead to surgical error, as categorized by the HFACS. These include ­factors that affect us as individuals, such as tiredness and fatigue; nutritional status; emotional states, including anger and stress; multi-­tasking; and loss of situational awareness. These will now be considered further:

Tiredness and fatigue Commercial aviation recognizes how tiredness and fatigue can influence personal performance and increase the likelihood of accidents, and as a result, rules are in place for maximum work hours. Tiredness (a state that can only be reversed by sleep) and fatigue (more complex in its aetiology and can be the result of chronic tiredness and/or physical or mental exhaustion) are both found in surgical team members. Both

Human factors in surgery

7

Before induction of anaesthesia Ask the patient to confirm his/her identity, procedure, site and consent.

Confirm the operating site has been marked, if applicable.

Confirm the anaesthetic machine and the medication checks are complete.

Confirm the pulse oximeter is working.

Check whether the patient has: • A known allergy.

• A difficult airway.

• An aspiration risk.

Check the anticipated blood loss, noting particularly if >500 mL (>7 mL/kg for children).

Before skin incision Team members to introduce themselves by their name and role.

Confirm the patient’s procedure and where the incision will be made.

Confirm whether antibiotic prophylaxis has been given or prescribed.

Surgeon to identify: • Critical or non-routine steps.

• How long the case will take.

• The anticipated blood loss.

Anaesthetist • Identify any patient-specific concerns.

Nursing and wider theatre team • Has sterility been confirmed?

• Are there any equipment issues or any concerns?

Imaging • Has the essential imaging been reviewed, or is it displayed?

Before the patient leaves the operating room Nurse confirms: • The completion of instrument, swab and needle count.

• The correct labelling of specimens.

• The identification and reporting of any equipment problems.

Surgeon, anaesthetist and nurse identify key concerns for recovery and management of the patient.

Figure 2.2 The WHO surgical safety checklist.

can reduce complex cognitive tasks, decision-­making and situational awareness as well as impairing our technical and physical performance. The value of taking regular short breaks, for example, during a long and complex 8-­hour operation is not only beneficial for individuals and teams but may also prevent errors.

Most of us would not drive for 8 hours non-­stop, so why can it be deemed safe to do so for surgery? One useful fact to remember is that our cognitive function after being awake for 18 hours is like being twice over the UK legal alcohol limit for driving. Increasingly, employing hospitals recognize that tired clinicians are much more likely to make a mistake, not to mention the effects on mood and general well-­being. No one else knows how an individual feels, and if they have been operating throughout the night and are

expected to work the following day, the few words ‘I don’t feel safe’ can be very powerful when discussing with managerial or other clinical colleagues.

Hydration and nutritional status Hydration, nutrition and individual recovery are often overlooked human factors but are crucial in the operating theatre to maintain performance. Even small deficits in total body water can have a significant impact on cognitive function, resulting in poorer decision-­ making, causing sleepiness, apathy, headaches and impatience. For example, a 1–2 kg loss in body water in an average-­build individual reduces cognitive function by 15–20%. This tends to happen slowly so that we are not aware our performance is deteriorating. Good

8

Human factors in surgery

Table 2.1 Simplified Human Factors Analysis and Classification System (HFACS) relevant to surgery The different levels are analogous to the holes in the Swiss cheese model lining up to cause an error.

Organizational influences within the hospital • Hospital targets and pressures to deliver results (either perceived or real).

• Climate, process and resource management within the hospital.

• Communication, training and recognition by the senior management of human factors responsible for possible errors.

Unsafe supervision • Inadequate supervision of trainees or other healthcare staff.

• Failure of briefings/complacency with the WHO checklist.

• Failure of the team to know what to do when things go wrong.

• Loss of situation awareness, especially if not recognized by the theatre team.

Preconditions to unsafe acts • Fatigue, hunger and nutritional status.

• Emotional influences (anger and personal issues) and running late.

• Tiredness, boredom and communication issues, remember HALT – hungry, anxious/angry, late, tired.

• Environmental factors: background noise, distractions, lighting, ambient temperature and humidity.

• Panic.

Unsafe acts (less likely) • Unfamiliar with changes from what is seen as a ‘normal event’.

• Distracting and multi-­tasking.

• Operating outside of one’s area of expertise or following a long period of no operating (surgical currency).

hydration is particularly important if personal protective equipment (PPE) is being worn, as this can increase the rate of perspiration and loss of body water.

Water requirements are unique to individuals, and while a multitude of factors, including body mass, ambient temperature, pregnancy and diet, play a role, the minimum requirement is approximately 2 L/ day.

Good and balanced nutrition when distributed over a sensible time period also helps optimize personal performance and supports complex mental and physical tasks over a sustained period. An example of this is a well-­balanced, small-­portioned meal consisting of complex carbohydrates, protein and healthy fats every 3–4 hours. In contrast, large meals eaten over erratic time periods consisting of simple sugars or processed foods are more likely to produce fluctuating energy ­levels, which can have a detrimental effect on our work.

One only needs to look at athletes to realize how effective good nutrition can be on improving performance.

Pre-­planned breaks during long operating lists, clinics and on-­call periods also ensure enough opportunity can be afforded for all team members to recover.

Emotion and stress Mental perspective and its impact on work performance needs to be recognized. Powerful emotions such as

anger or upset can easily interfere with decision-­making while performing a task that requires intense concentration. The operating theatre can itself be an environment that can be stressful for members of the surgical team – many would have witnessed colleagues raise their voices or become angry – one of the reasons being a result of stress or other factors that align. During such times, error is far more likely, not to mention the potential effect of loss of civility on the wider team, which can lead to respect being lost, amongst other negative effects.

The value of pausing during an operation (if it is safe to do so) to address these underlying issues may reduce the likelihood of error. We recommend taking a short break, again if it is safe to do so. Bringing the aforementioned factors together, the easily remembered pneumonic HALT – hunger, anger/anxiety, lateness (or lonely), tiredness – is a powerful reminder of the factors that can lead to surgical error as well as recommending the importance of stopping when one or more of these factors arise. Recognizing the impact of stress and emotion not only helps reduce the risk of error but also benefits surgical training and more effective and happier team working, all of which ultimately improve overall patient management. ‘Lonely’ has also been included as this word introduces the idea of remembering the value of involving colleagues for complex cases or after

Human factors in surgery

9

Table 2.2 Situations that might increase the chance of an error in the operating theatre environment Being aware of the following risk factors for error can help improve situational awareness: • High physical or mental workloads.

• Interruptions and distractions during key parts of an operation.

• Tasks requiring an ‘out of normal’ response and/or unanticipated new tasks.

• Multi-­tasking.

• Changes in physical environment.

a prolonged period of no operating (during COVID-­19, for example). Dual surgeon operating can be very useful in this regard, and not only can this give surgeons confidence, but it can also improve patient outcomes.

c­ ommences can reduce the likelihood of a startle ­reaction and ensures the team is best prepared.

Situational awareness

The concept of Patient, Procedure, People (PPP) has recently been introduced. Essentially, it is an adaptation of the aviation mnemonic, aviate, navigate, communicate (ANC). This is a useful way of regaining situational awareness when something does not seem quite right. In some circumstances, it may be the procedure that needs re-­discussing first, to help regain situational awareness. In most instances, stepping back from the acute situation (if safe to do so) and discussing with the team is the best way to understand the problem and decide the best course of action.

A simple definition of situational awareness is being aware of what is going on around us. Awareness and appreciation of several factors that increase the risk of medical error (Table 2.2) can be used to help improve situational awareness for both individuals and the whole team. Situational awareness is dynamic and can change quickly.

An important concept to be aware of is how situational awareness can change or degrade over time in different circumstances and our ability (or not) to adapt to it. Scenarios in which a surgeon may become fixated on a task, develop tunnel vision and become blind to other factors may readily occur. Surgeons can lose their situational awareness, especially if they have confirmation bias in which they are looking for clues or information to confirm the direction they are following. This could include convincing oneself of an anatomical structure or location when it is something quite different. As a result, many errors have occurred, including, for example, cut bile ducts, ureters and important nerves.

Recognizing the value of situational awareness alongside a well-­briefed and subsequently de-­briefed team, all of whom feel safe and able to voice their concerns, provides the best environment to reduce the risk of medical error taking place. This way, team members are looking out for each other, thereby improving safety and more effective working. By actively thinking ahead (having the best situational awareness), an error can often be avoided. For example, the best drivers are those who anticipate problems early, thereby avoiding potentially hazardous situations. In a similar way, thinking and discussing with the team about any potential ‘what if?’ scenarios before an operation

Patient, Procedure, People

The team brief, lowering authority gradients and ensuring good communication The team brief Patient care is rarely, if ever, performed in isolation from other team members. The introduction of the WHO surgical safety checklist (Figure 2.2) and team brief has brought significant improvements to patient safety in theatre. It involves theatre staff standing together and introducing themselves and their roles.

The lead surgeon describes the planned procedure, details any anticipated critical events and confirms that the necessary imaging has been reviewed; the anaesthetist identifies any patient-­specific concerns; and the nursing staff ensure they know about any special equipment that may be required.

Enhancing team working, understanding, valuing and reducing hierarchy, all contribute towards safer patient outcomes. The way in which a briefing is conducted is important. It should not be rushed, and from the outset, all team members should feel valued equally and empowered to

10

Human factors in surgery

Table 2.3 Items to consider during a team briefing A well-­prepared team is advantageous, in that every member knows their role and looks out for their colleagues.

It can also help team members to feel valued.

Briefing Introductions, open culture, ‘Please speak up if concerned’.

Leadership, team working and decision-­making.

Think about the ‘what if?’ scenarios that might occur during a procedure.

Identify the major steps and who will be doing what.

Ask ‘What am I expected to do if and when something goes wrong?’

Situational awareness – how to intervene when something does not seem right.

Debriefing A debrief is a powerful way to develop and enhance team working for future operating sessions.

• What went well?

• What should we do differently next time?

• What do you think about my performance today?

• Saying ‘Thank you’ to the team!

speak up if they have any concerns, without fear of retribution. Table 2.3 provides a summary of items that may be included in both briefing and debriefing sessions. The team brief should also stress the importance of looking out for each other to reduce the likelihood of losing situational awareness and highlighting when factors such as tiredness and stress are observed in others.

Tunnel vision During periods of intense concentration, surgeons can become tunnel visioned and quickly lose track of time. Several hours can pass, and the reliance on others to keep an eye on the clock and suggest a short break perhaps after 3 hours is good practice.

Distraction A distraction while you are concentrating can have a negative effect on performance. If there are safety-­critical times during the operation, these should be raised at the team brief, and distractions should be kept to a minimum. The sterile cockpit approach (where pilots focus only on flying when below 10,000 ft, with no distractions) is a valuable technique to apply in theatre. A simple distraction such as a telephone call asking for advice during a complex part of an operation significantly raises the risk of error. It is far better to either limit distractions (including noise) during these times or stop and focus on one task at a time instead of multi-­tasking.

Debrief At the end of the operating list, it is good practice to conduct a short debrief. This does not necessarily have to be formal, but it gives an opportunity to discuss what went well and what could be improved next time. The power of saying thank you to the team cannot be emphasized enough. Gaining feedback from other team members on our own performance is also valuable and builds practice and non-­technical skills.

Hierarchy In aviation, the most junior airline pilot is actively encouraged to be able to question the most senior Captain without fear. Similarly, empowering all surgical team members, including medical students, trainees, nurses and non-­clinical staff, to voice their concerns ensures a safe working environment for everyone. Of course, there has to be a team leader and hierarchy so that the wider team appreciates who is ultimately responsible. A flat hierarchy is as dangerous as a steep one as no one quite knows who is doing what as there is no leadership. However, what is most important is to know that any team member can speak up, if concerned, without fear and that their concern will be listened to.

Communication Effective communication between team members is an essential element to good team working and interaction.

Ninety percent of communication is non-­verbal, so

Human factors in surgery

while wearing PPE, instructions may not be heard or understood due to the face being covered and voice being muffled. The regular use of open questions such as: ‘What do you think we should do?’ and ‘What would you suggest here?’ are good at bringing the team together. The use of pronouns (e.g. ‘pass me it or that) should be avoided, especially at safety-­critical times, and instead, usage of proper nouns to ensure clear instructions (such as the name of a required instrument) is much better. Finally, ‘repeat back’ is a useful tool to confirm that a message has been heard

11

and understood by the receiver. Just because a team member has said something does not automatically mean that others have heard and understood the message or instruction.

In summary, human factors application is essential to ensure both individuals and teams are best ­optimized to care for patients. Some elements are just common sense, such as stopping for a short break regularly just as we would do while driving a long distance.

However, it can be all too easy to leave common sense at the front door of the hospital when we come to work.

3 Fluid and nutrition management Lynsey Spillman Learning objectives ✓✓ To understand the distribution and composition of body fluids and how these may change following surgery. ✓✓ To understand the role of perioperative nutrition.

The management of a patient’s fluid status is vital to a successful outcome in surgery. This requires preop­ erative assessment, with resuscitation if required, and postoperative replacement of normal and abnormal losses until the patient can resume a normal diet. This chapter will review the normal state and the mecha­ nisms that maintain homeostasis and will then dis­ cuss the aberrations and their management.

Body fluid compartments In an ‘average’ person, water contributes 60% to the total body weight: 42 L for a 70 kg man. Forty percent of the body weight is intracellular fluid, while the remaining 20% is extracellular. This extracellular fluid can be subdivided into intravascular (5%) and extravascular or interstitial (15%). Fluid may cross from compartment to compartment by osmosis, which depends on a solute gradient, and by filtration, which is the result of a hydrostatic pressure gradient.

The electrolyte composition of each compartment differs (Figure 3.1). Intracellular fluid has a low sodium Ellis and Calne’s Lecture Notes in General Surgery, Fourteenth Edition.

Edited by Christopher Watson and Justin Davies. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/Watson/GeneralSurgery14

and a high potassium concentration. In c­ ontrast, extra­ cellular fluid (intravascular and interstitial) has a high sodium and low potassium concentration. Only 2% of the total body potassium is in the extracellular fluid.

There is also a difference in protein ­concen­tration within the extracellular compartment, with the ­interstitial fluid having a very low concentration compared with the high protein content of the intravascular compartment.

Knowledge of fluid compartments and their compo­ sition becomes important when considering fluid replacement. In order to fill the intravascular compart­ ment rapidly, a plasma substitute or blood is the fluid of choice. Such fluids, with high colloid osmotic potential, remain within the intravascular space, in contrast to a crystalloid solution such as compound sodium lactate (Hartmann’s1) solution, which will distribute over the entire extravascular compartment, which is four times as large as the intravascular compartment. Thus, of the original 1 L of Hartmann’s solution, only 250 mL would remain in the intravascular ­compartment. Five percent

1 Alexis Frank Hartmann (1898–1964), Professor of

Paediatrics, St Louis Children’s Hospital, St Louis, USA. Hartmann added sodium lactate to a physiological salt solution that was developed by Sydney Ringer (1834–1910), Professor of Materia Medica and Therapeutics, University College Hospital, London, and formerly also a physician at Great Ormond Street, London.

Fluid and nutrition management

Vomiting and nasogastric tube loss

‘Pure’ water loss (e.g. fever, dehydration, hyperventilation)

Gastric fluid contains: 20–60 mmol/L Na+ 14 mmol/L K+ 140 mmol/L Cl– 60–80 mmol/L H+.

Mainly insensible water loss (i.e. relatively low electrolyte content); results in potential hypernatraemia

13

Excessive loss causes a hypochloraemic (hypokalaemic), metabolic alkalosis. Correction requires supplemental K+ and Cl–.

Biliary drainage loss 145 mmol/L Na+ 5 mmol/L K+ 105 mmol/L Cl– 30 mmol/L HCO3–

Pancreatic drain or fistula 125–138 mmol/L Na+ 8 mmol/L K+ 56 mmol/L Cl– 85 mmol/L HCO3–

Diarrhoea or excess colostomy loss

Jejunal loss via stoma or fistula

30–140 mmol/L Na+ 30–70 mmol/L K+ 20–80 mmol/L HCO3–

140 mmol/L Na+ 5 mmol/L K+ 135 mmol/L Cl– 8 mmol/L HCO3–

High-volume ileal loss via new stoma, high stoma or fistula 100–140 mmol/L Na+ 4–5 mmol/L K+ 75–125 mmol/L Cl– 0–30 mmol/L HCO3–

Inappropriate urinary loss (e.g. polyuria) Na+ and K+ variable, depending on urine output.

Low-volume ileal loss via established stoma or low fistula 50–100 mmol/L Na+ 4–5 mmol/L K+ 25–75 mmol/L Cl– 0–30 mmol/L HCO3–

Ongoing blood loss (e.g. melaena)

Figure 3.1 Estimated electrolyte concentration in body fluids encountered post surgery.

Source: From National Institute for Health and Care Excellence (NICE) https://www.nice.org.uk/guidance/cg174/chapter/1-recommendations

dextrose, which is water with 50 g of dextrose added to render it isotonic, will redistribute across both intracel­ lular and extracellular spaces.

Fluid and electrolyte losses In order to calculate the daily fluid and electrolyte require­ ments, the daily losses should be measured or estimated (Figure 3.1). Fluid is lost from four routes: the kidney, the gastrointestinal tract, the skin and the respiratory

tract. Losses from the last two routes are termed insensi­ ble losses. In addition, losses from surgical drains should be accounted for. Weighing the patient daily can give a good indication of overall changes in fluid balance.

Normal fluid losses The kidney In the absence of intrinsic renal disease, fluid losses from the kidney are regulated by aldosterone and antidiuretic hormone (ADH). These two hormone

14

Fluid and nutrition management

Table 3.1 Normal daily fluid losses Fluid loss

Volume (mL)

Na+ (mmol)

K+ (mmol)

Urine

2,000

80–130

60

Faeces

300

Insensible

400

Total

2,700

systems regulate the circulating volume and its ­osmolarity, and are thus crucial to homeostasis.

Aldosterone responds to a fall in glomerular perfu­ sion by salt retention. ADH responds to the increased solute concentration by retaining water in the renal tubules. Normal urinary losses are around 1,500–2,000 mL/day (Table 3.1). The kid­ neys control water and electrolyte balance closely and can function in spite of extensive renal disease.

Damaged kidneys leave the patient exquisitely vul­ nerable to inappropriate water and electrolyte administration.

The gastrointestinal tract The stomach, liver and pancreas secrete a large vol­ ume of electrolyte-­rich fluid into the gut. After diges­ tion and absorption, the waste material enters the colon, where the remaining water is reabsorbed.

Approximately 300 mL is lost into the faeces each day.

Insensible losses Inspired air is humidified in its passage to the alve­ oli, and much of this water is lost with expiration.

Fluid is also lost from the skin, and the total of these insensible losses is around 700 mL/day. This may be balanced by insensible production of fluid, with around 300 mL of ‘metabolic’ water being produced endogenously.

Abnormal fluid losses The kidney Most of the water filtered by the glomeruli is reab­ sorbed in the renal tubules, so impaired tubular function will result in increased water loss. Resolving acute tubular necrosis (Chapter 43), diabetes insipi­ dus and head injury may result in loss of several litres of dilute urine. In contrast, ectopic production

of ADH by tumours (the syndrome of inappropriate ADH, or SIADH) causes water retention and haemodilution.

The gastrointestinal tract Loss of water by the gastrointestinal tract is increased in diarrhoea and in the presence of an ileostomy, where colonic water reabsorption is absent.

Vomiting, nasogastric aspiration and fistulous losses result in loss of electrolyte-­rich fluid. Disturbance of the acid–base balance may also occur if predominantly acid or alkaline fluid is lost, as occurs with pyloric steno­ sis and with a pancreatic fistula, respectively.

Large occult losses occur in paralytic ileus and intestinal obstruction. Several litres of fluid may be sequestered in the gut, contributing to the hypovolae­ mia. Resolution of an ileus is marked by absorption of the fluid, and the resultant hypervolaemia produces a diuresis.

Insensible losses Hyperventilation, as may happen with pain or chest infection, increases respiratory losses. Losses from the skin are increased by pyrexia and sweating, with up to 1 L of sweat per hour in extreme cases. Sweat contains a large amount of salt.

Effects of surgery The stress response to surgery includes the release of ADH/vasopressin and catecholamines and activation of the renin–angiotensin system, resulting in oliguria and water retention. In spite of oliguria, the patient may be euvolaemic, hence the need to fully assess the state of hydration before prescribing postoperative fluids. Unnecessary administration of saline, for example, may expand the blood volume and thus reduce the haematocrit; overexpand the interstitial space, resulting in oedema; and provide a salt load that the patient cannot excrete.

Potassium is released by damaged tissues, and its concentration may be further increased by blood transfusion, each unit typically containing in excess of 10 mmol. If renal perfusion is poor and urine out­ put sparse, this potassium will not be excreted and instead accumulates; the resultant hyperkalaemia causes life-­threatening arrhythmias. This is the basis of the recommendation that supplementary potas­ sium may not be necessary in the first 48 hours fol­ lowing surgery or trauma.

Fluid and nutrition management

Prescribing fluids for the surgical patient

Special investigations

The majority of patients require fluid replacement for only a brief period postoperatively until they resume a normal diet. Some require resuscitation preopera­ tively, and others require replacement of specific losses such as those from a fistula. In severely ill patients, and those with impaired gastrointestinal function, long-­term nutritional support is necessary.

•

•

•

Preoperative fluid management Patients awaiting elective surgery can continue clear fluids up to 2 hours before surgery, unless they have a disorder affecting their gastric emptying (e.g. carci­ noma of head of pancreas; diabetes mellitus).

Preoperative carbohydrate drinks, 2–3 hours before surgery, have been shown to reduce preoperative anxiety and postoperative nausea and vomiting and are now routine adjuncts to preoperative care in elec­ tive surgery.

•

•

15

Full blood count – a high haemoglobin may repre­ sent haemoconcentration.

Urea, creatinine and electrolytes – important to ensure the correct electrolyte replacement to cover losses; raised urea may represent either renal impairment (creatinine also raised), dehy­ dration or blood in the gut.

Urinary sodium – useful in the presence of high volume gastrointestinal losses. Reduced urinary sodium excretion (<30 mmol/L) suggests total body sodium depletion. These measures are not reliable in the presence of renal impairment or diuretic usage.

Serum chloride – useful in patients receiving a lot of normal saline to avoid hyperchloraemia. If pre­ sent, saline needs to be switched to an alternative fluid with less chloride.

Drain fluid electrolytes – where there are persis­ tently high fluid losses, for example, from high fis­ tulas, it may help to measure the electrolyte content to better judge the replacement fluid needs.

Intravenous fluid management

Resuscitation

Assessment of fluid requirements

Thirst, dry mucous membranes, loss of skin turgor, tachycardia and postural hypotension, together with a low jugular venous pressure, suggest a loss of between 5% and 15% of total body water. Fluid losses of under 5% body water are difficult to detect clini­ cally; over 15%, there is marked circulatory collapse.

Fluid replacement in adults should comprise a crys­ talloid with a high sodium content (130–154 mmol/L, e.g. Hartmann’s or 0.9% saline; Table 3.2), with a bolus of 500 mL over less than 15 minutes. Human albumin 4–5% solution may be considered for fluid resuscita­ tion only in patients with severe sepsis. Following a fluid challenge, the patient should be reassessed – did the pulse fall and the jugular venous pressure (JVP) rise, and did the hourly urine output increase?

As an example, consider a 70 kg man presenting with a perforated peptic ulcer. On examination, he is noted to have dry mucous membranes, a tachycardia and slight postural fall in arterial blood pressure. If the loss is estimated at 10% of the total body water, itself 60% of the body weight, the volume deficit is 10% × 60% of 70 kg, or 10% of 42 L = 4.2 L. This loss is largely isotonic (gastric juices and the peritoneal inflammatory response), hence infusion of a balanced crystalloid solution (e.g.

Hartmann’s solution) is appropriate. A general rule of thumb is to replace half of the estimated loss quickly and then reassess before replacement of the rest.

Assessment of fluid requirements involves history and examination.

History • • •

Sensation of thirst: implies at least 2% volume depleted Fluid balance: what were the previous fluid intake and losses?

Abnormal losses and their nature, e.g. nasogastric output

Examination • • • • • • • •

Pulse – Is there a tachycardia?

Jugular venous pressure – Is the pressure wave ­visible, and if so, how high is it raised?

Capillary refill – should be less than 2 seconds.

Skin turgor.

Blood pressure – Is there a postural fall?

Is there evidence of fluid overload? Pulmonary oedema or peripheral oedema.

Weight, useful to monitor losses. Minimum of twice a week.

Urine output – hourly monitoring in early postop­ erative or shocked patients; daily outputs in main­ tained patients. Daily collections are often not accurate, hence daily weights may be preferred.

16

Fluid and nutrition management

Routine maintenance fluids Table 3.1 shows the normal daily fluid losses.

Replacement of this lost fluid in a typical adult is achieved by the administration of: • • •

25–­30 mL/kg/day of water 1 mmol/kg/day potassium, sodium and chloride 50–100 g/day glucose to limit starvation ketosis – N.B.: this does not meet nutritional needs.

5% ­dextrose only contains 50g/L dextrose.

Special considerations • •

•

•

Obese patients: adjust the intravenous (IV) fluid prescription to their ideal body weight.

Renal failure: adjust the volume to urine output plus insensible and special losses with care when prescribing potassium as this is not excreted in renal failure.

Cardiac failure and the elderly and frail: these patients are prone to accumulate fluid in the lungs.

Malnourished – see later. These patients are at risk of refeeding syndrome.

A typical prescription would be 25–30 mL/kg/day 0.18% saline in 4% dextrose with 1 mmol/kg potassium.

Therefore, for a 70 kg man, this may comprise 3 L of 4% dextrose/0.18% saline (31 mmol NaCl per litre), with 20 mmol potassium added to each 1 L bag (Table 3.2).

Excessive amounts of hypotonic crystalloid may cause hyponatraemia, particularly in children and the elderly. An alternative regimen involves the use of Hartmann’s solution (Table 3.2). Adjustments to the fluid regimen should be based on regular clinical examination, measurement of losses (e.g. urine ­output), daily weights (to assess fluid changes) and regular blood samples for electrolyte determination.

For example, if the patient is anuric, 1 L/day of 5% dextrose without potassium may suffice.

Replacement of special losses Special losses include nasogastric aspirates, losses from fistulas, diarrhoea and stomas, and covert losses such as occur with an ileus (Figure 3.1). Loss of plasma in burns is considered elsewhere (Chapter 10). All fluid losses should be measured carefully when possi­ ble, and this volume added to the normal daily requirements. The composition of these special losses varies, but as a rough guide, replacement of excessive gastric fluid loss with an equal volume of normal

Table 3.2 Electrolyte content of intravenous fluids Intravenous infusion

Human plasma

0.9% saline

4% dextrose* 0.18% saline

Hartmann’s

Plasma-­ Lyte 148

4% gelatine

5% albumin

Osmolarity

275–295

308

283

278

295

290

300

pH

7.35–7.45

4.5-­7.0

4.5

5.0–7.0

6.5–8.0

Na+ (mmol/L)

135–145

154

31

131

140

145

150

K+ (mmol/L)

3.5–5

5

5

Ca2+ (mmol/L)

2.2–2.6

2

Mg2+ (mmol/L)

0.8–1.2

Cl– (mmol/L)

95–105

145

150

Glucose (mmol/L)

3.5–5.5

Lactate (mmol/L) 1.0–2.0 HCO3– (mmol/L)

1.5 154

31

111

98

222 (40g) 29

23–27

Acetate (mmol/L)

27

Gluconate (mmol/L)

23

Note: Dextrose is the D-­isomer of glucose, the only isomer that can be metabolized. Dextrose/saline combinations come in varying mixtures, including 4% dextrose, 0.18% saline, so the mixture must be specified clearly.