PvO2 and PCWP are the most sensitive indicators of intravascular volume changes during graded hemorrhage in the animal model. We examrned the effect of moderate {luid loading during clectrically induced ventricular fibrillation (VF) and CPR in 18 dogs (12 26 kg). Oxygen uptake was measured with a modified recording spiromctcr. Blood flows were measured with tracer mrcrospheris (15 + 0.9p dia) at 5, 13, and 20 min a{ter the initiation of VF and CPR. After 10 min of CPR, 9 dogs receivcd a rapid in{usion (11 ml/kg IV) of whole blood and 9 dogs received Rrngcr's. Differcnces between thc blood- and the Ringer's-treated groups were not signi{icant for any of the measurcd variablcs. Howcver, some ef{ccts of fluid loading were signi{icant. Aftcr fluid loading, cardiac output (CO) increased 34% lat 13 min) and then decrcased (at 20 min) to 84o/oof the control (5 min) valuc. Despite the increasein CQ le{t ventricular (LV) periusior-r lcll to 74'1, of control after fluid loading, while brain flow dccreascd to 65o1,of control. At 20 min (10 min aiter fluid loading), CO anci brain flow returned to near control value, while LV flow remained low. Oxygen uptake was not significantly a{fectcd by fluid loading with cithcr whole blood or Rrnger's. LV Time CO (min) (mL/min/kg) (mL/min/g) Brain (mL/mln/g) 39 PA Maningas, MD; KE Friedl, PhD; SC Dronen, MD / Departments o f E m e r g e n c y M e d i c i n e a n d C l i n i c a l l n v e s t i g a t i o n ,M a d i g a n A r m y Medica Center, Tacoma, WA Rccent intcrest has developed about the clinical application of transcutancous oxygen monitoring in thc traumatized patient. While orior studies l-ravcdemonstrated a reduction in transcutancous vaiues during hemorrhagic shock, the effcct of hyperoxia on transcutar-reous valucs during hemorrhage has not bcen str-rdicd. Tl-ris study was undcrtaken to evaluate the influence o{ oxygcn t1]erapy on transcutancous mcasurefiIcnts during graded hcmorrl-rage. Fifteet't mongrel dogs wcre bled and reinfused 40% of tl-rcir calculatcd intravascular volume over 90 min (35 cclkg). Or-rcgroup (n - 9) was blcd whilc spontaneously breathing room air. Tlrc sccond group (r'r : 6) undcrwent identicai hemorrhage, but was maintaincd or-ran FiO2 of 40% durir-rg thc eutirc experimcnt. Thcro was r-ro significant diffcrcnce bctween thc 2 groups ir-rrcgard to cardiac indcx, mixcd venous oxygcn tension and scrun'r lactzrtcs prror to hcmorrhage, aftcr hernorrhage, and aftcr rcinfusion of shctl blood. Thc PaO2 and P1.O2 of anlmals maintaincd on ar-rFiO2 of 40(2, wcre highcr than thosc on room alr ln c z r c ho f t h c 3 p c r i o d s { 1 ' < . 0 1 ) . T h c P , . O 2 o f t h c o x y g e n - t r c a t e d grolrp, though lighcr, foliowcd closcly thc changcs that occurrcd ii-r th" .u,rt-t-t:rir anirlals lr : .76). Thcrc was no signi{lcant diffcrcncc bctwccn groups ir-r thc pcrccntagc change in P,.O2 attcr hcmorrh:rgc or rcinfusion. Thc transcutancous oxygt'n index (P,.O2/PaO2) was significantiy lower in thc oxygcn-trcatcd group p . i i , r i o h c m o r r h a g c a n d a f t c r r c i n f u s i o n 1 P < . 0 0 1 ) .W c c o n c l u d c that transcutancous oxygcn valucs are elevatcd as a conscquencc o{ l-rypcroxia. Thcsc valucs rcmain significantly higher, though follow closclv thc trcnd of thosc lcvels obtaincd at room air during gradcd hcmorrhagc. Thus thc use of oxygen as adiunctivc thcrapy for thc traumatrzcd paticnt may alter thc intcrpretation of tl-rc initiai transcutaneous oxygen rreasurcment, howcver, it docs r.rot prccludc tl-rc use of this device as a trcnd monitor during hcmorrhagc. Uptake (mL/mln/kg) 0 . 6 5 + 0 0 6 0 . 7 5* 0 . 0 8 4 . 1 8+ 0 2 9 5 6 5 . 8+ 5 . 0 13 B B . 4t 8 . 6 - 0 . 4 8 t 0 . 0 8 0 . 4 9 t 0 0 6 . 4 2 9 + 0 . 2 7 20 5 5 . 1+ 5 . 0 - 0 5 1 + 0 . 0 8 0 . 7 3 : t 0 . 1 0 4 4 6 + 0 . 3 2 .lndicatessrgnlficant fromcontrol(5 min)value(o<0 01) difference Thc changcs in organ pcr{usion can bc cxplainccl in p:rrt by thc concurrcnt changcs in blood prcsslrrcs (BP). Prcvious stlrdics havc shown that tl-relevcl of ccntral :rrtcrial diastolic prcsslrrc (CADP) and thc ccntral artcnovcnous diastolic prcssurc diffcrcncc (CAVDP) corrclatc witl-r vital organ perfusion. h'r this stucly, ccntral venous diastolic BP incrcascd significantly (9.2 to 13.9 rnm Hg) aftcr fluid 1oad. Howcvcr, CADP did not risc proportionatcly (31.9 to 33.9 rnrn Hg) ancl thc CAVDP actuaily dccrcascd. Althougl-r fluid loading during CPR improvcs CO, flow to thc hcart and brain dccrcascs. Furthcr, thcrc is no inctcasc in oxygcn consumpt i o n , i n d i c a t i r - r gt h a t f l u i d l o a d i n g c l o c s n o t i m p r o v c m c t a b o l i c statlls. 38 Effect of Hyperoxia on Transcutaneous Oxygen Measurements During Graded Hemorrhage Gomparison of Cardiorespiratory' Biochemical, and Transcutaneous Parameters During Graded Hemorrhage Model for Anaphylactic A Hemodynamic A ll -1, Shock W G B a r s a n , M D , J B H e d g e s , M D , F A C E P ;S S y v e r u d , M D ; W C D a l s e y , M D / D i v i s i o n o f E m e r g e n c y M e d i c i n e , U n i v e r s i t yo f C i n c i n n a t iM e d i c a l C e n t e r ,C i n c i n n a t i The treatment of cardiovascular collapse in anaphylactic shock is largely cmpiric and not wcll understood. A simple animal model was developed to evaluatc the hemodynamic altcrations in anaphylaxis. This modcl provides a method for investigating ncw treitmcrrt modalitics. Six adult New Zealand whitc rabbits of both sexes wcre studicd. All animals weighcd 3.8 to 5.3 kg. Sensitization was accomplished with a 2-cc subcutaneous dose ol irorsc serum followed in 2 days with a 2-cc intravenous dosc. At lcast 14 days elapsed a{ter the intravenous dose before a 1.0-cc challcnge dosc of horse scrum was givcn. On the day of the challcngc dose, a fcmoral artcrial cathetcr, arterial tcmperature probe, and right atrial cathcter were placed under mcthoxyflurane anesthesia vra nosecone. The temperature probe was posrtioned in the aortic arch. The methoxy{lurane was discontinued and the only sedation givcn during thc shocl< phase was intravenous diazepam (0.1-0.5 mg/kg). At least 30 min after thc methoxy{lurane was drscontinued, the chailenge dose of horse serum was given through the right atrial cathetcr. Before and durrng the shock phase, cardrac rhythm, arterial pressure, and intravascular temperature were continuously monitored. Cardiac outputs {CO) were performed by a thermal dilution tcchnique using 0.8 cc of room temperature saline injectate through the right atrlal catheter. Tem- PA Maningas,MD; SC Dronen, MD; KE Fried , PhD / Departments o f E m e r g e n c y M e d i c i n e a n d C l i n i c a l I n v e s t i g a t i o n ,M a d i g a n A r m y Medical Centet Tacoma, WA Numerous parametcrs have becn suggested to aid in thc diagnosis, management, and prognosis of paticnts in hcmorrhagic shock. Among these are central venous pressure (CVP), pulmonary capiliary wcdge pressure (PCWP), mixed venous oxygen tension (PvO2), serum lactate, basc deficit, and transcutaneous oxygen tension (P."O2). This study was undertal