Intensive Care Med (2006) 32:1329–1335 DOI 10.1007/s00134-006-0241-3
Ralf-Peter Vonberg Tim Eckmanns Tobias Welte Petra Gastmeier
Received: 16 December 2005 Accepted: 17 May 2006 Published online: 21 June 2006 © Springer-Verlag 2006 R.-P. Vonberg (u) · P. Gastmeier Medical School of Hannover, Institute for Medical Microbiology and Hospital Epidemiology, Carl-Neuberg-Straße 1, 30625 Hannover, Germany e-mail: Vonberg.Ralf@MH-Hannover.de Tel.: +49-511-5324431 Fax: +49-511-5328174 T. Eckmanns Charité University Medicine, Institute of Hygiene and Environmental Medicine, Berlin, Germany T. Welte Medical School of Hannover, Department for Pneumology, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
ORIGINAL
Impact of the suctioning system (open vs. closed) on the incidence of ventilation-associated pneumonia: meta-analysis of randomized controlled trials
Abstract Objective: Ventilationassociated pneumonia (VAP) is a serious complication of patients in intensive care units (ICU) who require mechanical ventilation. The choice of suctioning system (open vs. closed) remains unresolved in evidence-based guidelines. This meta-analysis was carried out to analyze the effect of the type of suctioning system on the incidence of VAP. Design: A search of the literature was used to identify randomized controlled trials addressing this question. A meta-analysis was then performed to calculate the relative risk of ventilation-associated pneumonia acquisition with the two suctioning systems. Results: Nine trials were included, with 648 patients in the open suctioning group and 644 in the closed suctioning group. VAP occurred in 128 (20%) of the
Introduction Pneumonia is the most common nosocomial infection on intensive care units (ICUs) [1], and mechanical ventilation is a well known risk factor for acquiring nosocomial pneumonia [2]. Consequences of ventilation-associated nosocomial pneumonia are an increased length of ICU stay for more than 6 days, increased cost for health care systems by U.S.$10,000 per case, and a doubled risk of mortality of affected patients [3]. Two general types of suctioning systems are available: (a) open tracheal suctioning systems that need to become disconnected. These systems require single-use catheters and a sterile suctioning technique for the prevention of ventilation-associated pneumonia (VAP). (b) Closed tracheal suctioning systems
open suctioning group and in 120 (19%) in the closed suctioning group (relative risk 0.95). Conclusions: At a given pneumonia prevalence of 20% in ICU patients there was no significant advantage for the use of either suctioning system in this meta-analysis. The choice of suctioning system should therefore be based on handling, cost, and individual patient’s disease until more data are available. Keywords Suctioning systems · Meta-analysis · Nosocomial pneumonia
that do not become disconnected but rather involve use of multiuse catheters. Evidence-based guidelines for preventing nosocomial pneumonia have been published by the Centers of Disease Control and Prevention, but so far the relationship between VAP and the type of endotracheal suctioning system remains unresolved [4]. During use open systems may allow external pathogens to enter the patient’s airways, but frequent reuse of contaminated closed systems may also present some risk of infection. The effect of endotracheal suction system (open vs. closed) on the rate of VAP has been reviewed by several authors [5, 6, 7, 8], who have analyzed, however, only few randomized controlled trials (RCTs) among those available at present. These authors failed to ascertain any significant difference in the development of nosocomial pneu-
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monia with the two suctioning systems. Meanwhile additional RCTs addressing this question have been published. This meta-analysis was carried out to analyze the effect of the type of suctioning system on the incidence of VAP, including all the RCTs performed in adults available at present.
patient’s suctioning system was not changed at all unless it presented mechanical failure, or soiling, or the patient needed reintubation. In all other studies the closed suctioning system was exchanged every 24 h. The number of suctioning procedures as described by the authors often covers the routine suctioning management only. Additional procedures might have been performed by the discretion of the health care worker. No significant differences in the severity of the underlying disease were Materials and methods reported in either study. Definitions used for pneumoData acquisition nia determination in most studies were similar to the definitions as proposed by Centers of Disease Control Studies eligible for inclusion were found by a PubMed and Prevention. No patients became excluded after the search (from 1966 to 10 April 2006) using the fol- randomization process. lowing terms: (a) “randomized” or “randomised,” (b) “prospective,” (c) “open,” (d) “closed,” (e) “suctioning” or “suction,” (f) “tracheal” or “endotracheal”, and (g) “pneumonia.” All studies were then screened whether all Results of the following criteria were fulfilled: (a) reporting of the Risk of ventilation-associated pneumonia number of patients with open and with closed suctioning systems, (b) reporting of the number of VAP cases that A total of 648 patients were treated with open suctioning occurred in each group, (c) published as full manuscript. systems, 20% of whom acquired VAP, and 644 with Reference lists of all of these articles were searched for a closed system, 19% of whom acquired VAP. No study additional RCTs. Using the key words (a) “open,” (b) reported significant differences between the groups with “closed,” and (c) “suctioning” or “suction” the Cochrane respect to histamine-2 receptor antagonists, gastric acid Central Register of Controlled Trials was also searched to secretion inhibitors, patient’s tobacco use, or prevalence detect additional RCTs. of chronic obstructive lung disease. The pooled relative risk for closed suctioning systems is 0.95 (95% CI 0.76–1.18). The study by Adams et al. [14] is excluded Data analysis in this calculation as neither arm of the study contains any events. The test for statistical heterogenicity is not Data were extracted independently by all authors. The significant (p = 0.46), which means that there is only fixed-effects method was used to derive a summary very little heterogenicity between the studies. Figure 1 estimation as implemented in STATA 7 software (STATA shows the corresponding Forrest plot. Studies with smaller Statistics/Data Analysis 7.0, Stata, Texas, USA). Pro- population sizes have a relative risk less than 1 while tective effects with the 95% confidence interval were the study with the greatest number of patients shows one calculated, and testing for heterogenicity was performed. greater than 1. The overall relative risk is slightly below 1. Study characteristics A total of 12 citations were found by the PubMed search using the key words as described. One of these hits was of only preliminary data [9]. This study was published in full article form 2 years later. Two other references were excluded because they either failed to report data on pneumonia but concentrated on other cardiorespiratory parameters instead [10] or were conducted in premature infants [11]. The remaining nine studies [12, 13, 14, 15, 16, 17, 18, 19, 20] were included in this meta-analysis. The Cochrane Central Register of Controlled Trials revealed a protocol for this subject only, but no Cochrane review on this issue has been published yet [21]. Table 1 shows the characteristics of all studies included. In two studies [14, 18] no exact use interval of the closed Fig. 1 Forrest plot of meta-analysis (study by Adams et al. [14] is suctioning system was reported. In one study [20] the excluded)
Trauma (35)
Liver Trach transCare plant (20)
Johnson USA et al. [13]
Adams UK et al. [14]
Trach Care
Trach Care
Surgical (41), medical (43)
Deppe USA et al. [12]
Type of closed suctioning system
Type of ICU (no. of patients)
Country
ND
24
24
Hours of closed system use
Yes
Yes
Yes
Pneumonia at admission excluded
o: 10.0, c: 16.6
o: 16, c: 16
o: 12.4, c: 16.6
All of the following criteria must apply within 24 h: purulent sputum, temperature: ≥ 38.1◦ C or ≤ 35.9◦ C, new or progressive infiltrate in radiograph, leukocytes: > 12,000/mm3 or < 3,000/mm3 , time after admission > 48 h New or progressive pulmonary infiltrate in radiograph and at least two of the following criteria must apply: purulent sputum, temperature: ≥ 38.1◦ C without any known extrapulmonary source, leukocytes: > 12,000/mm3 Clinical pulmonary infection criteria (point score): temperature: 36.5–38.4◦ C (0 points), temperature: 38.5–39.0◦ C (1 point), temperature: < 36.0◦ C or > 39.0◦ C (2 points), leukocytes: 4,000–11,000/mm3 (0 points), leukocytes: 11,000–17,000/mm3 (1 point), leukocytes: > 17,000/mm3 (2 points), secretions: ± (0 points), secretions: + (1 point), secretions: ++ (2 points), PaO2 y/FIO2 Y inkPa: > 33 (0 points), PaO2 y/FIO2 Y inkPa: < 33 (2 points), PaO2 y/FIO2 Y inkPa: < 33 with ARDS (0 points), chest radiograph infiltrates: clear (0 points), chest radiograph infiltrates: patchy (1 point), chest radiograph infiltrates: localized (2 points), a sum score of at least 6 points and at least two of the following criteria must apply or alternatively a sum score of at least 8 points and at least one of the following criteria must apply: clinical course on/off antibiotics consistent with pneumonia, lack of evidence of alternative source of sepsis, lung biopsy or postmortem histology demonstrating pneumonia
No. of open Criteria for diagnosis nosocomial of ventilationand closed associated pneumonia suctioning procedures per day
Child-Pugh score (no. of patients): o: A (2), B (7), C (1), c: A (3), B (7), C (0)
Average APACHE score: o: 12, c: 12
Medical ICU: average APACHE II score of all patients: 25.1; surgical ICU: ND
Severity of illness
ND
ND
ND
Average no. of days of mechanical ventilation
Table 1 Characteristics of included studies of endotracheal suctioning (open vs. closed) (o open, c closed CFU colony forming units, APACHE Acute Physiology and Chronic Health Evaluation, SAPS Simplified Acute Physiology Score, ND no data)
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Medical- ND surgical (47)
Zeitoun Brazil et al. [16]
Trach Care
SteriCath
Rabitsch Austria Medical et al. [17] (24)
Medical (78)
Medical- Hisurgical Care (443)
Topeli Turkey et al. [18]
Lorente Spain et al. [19]
SteriCath
Neurosurgical (104)
Combes France et al. 2000 [15]
Type of closed suctioning system
Type of ICU (no. of patients)
Country
Table 1 Continued
24
ND
24
24
24
Hours of closed system use
Yes
Yes
Yes
Yes
Yes
o: 8.3, c: 8.1
ND
o: ≥ 6, c: ≥ 6
ND
o: 12, c: 12
All of the following criteria must apply: purulent endotracheal secretions, temperature: ≥ 38◦ C without any known extrapulmonary source, new and persistent infiltrate in radiograph leukocytes: > 10,000/mm3 or < 4,000/mm3 , time after beginning of ventilation > 48 h All of the following criteria must apply: purulent tracheobronchial secretions or changes in characteristics, temperature: ≥ 37.8◦ C, new or progressive infiltrate in radiograph, leukocytes: > 10,000/mm3 New or progressive pulmonary infiltrate in radiograph and at least one of thefollowing criteria must apply: radiographic evidence of cavitation, histological evidence of pneumonia, positive blood culture without another source evidence of infection, purulent tracheal aspirate (> 25 leukocytes per field), positive pleural fluid culture finding and one of the following criteria: (a) temperature: > 38.0◦ C, (b) leukocytes: > 10,0000/mm3 or < 3,000/mm3 New and persistent pulmonary infiltrate in radiograph and at least two of the following criteria must apply: temperature: > 38◦ C or < 35.5◦ C, leukocytes: > 10,000/mm3 or < 3,000/mm3 , purulent enodotracheal aspirate (≥ 10 leukocytes per field), time after beginning of ventilation > 48 h All of the following criteria must apply: new onset of purulent bronchial sputum, temperature: > 38◦ C or < 35.5◦ C, leukocytes: > 10,000/mm3 or < 4,000/mm3 , new and persistent infiltrate in radiograph, time after beginning of ventilation > 24 h, one of following “significant respiratory secretions”: tracheal aspirate: > 106 CFU/ml, bronchoalveolar aspirate: > 104 CFU/ml, protected brush catheter: > 103 CFU/ml, (if the CFU count was too low, a positive blood culture coinciding was required to fulfill this criterion)
Pneumonia No. of open Criteria for diagnosis nosocomial of ventilationat admisand closed associated pneumonia sion exsuctioning cluded procedures per day o: 14.1, c: 12.8
Average no. of days of mechanical ventilation
ND
Average APACHE II o: 12.7, score: c: 12.5 o: 15.8, c: 15.4
Average APACHE II o: 7.5, score: c: 8.2 o: 23.8, c: 25.6
APACHE II score did not differ between groups
Median APACHE II ND scores (no significant difference): o: 24, c: 22
Average SAPS I score: o: 6.91, c: 7.88
Severity of illness
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Medical- Hisurgical Care (457)
No routine change
Yes
o: 7.9, c: 8.1
All of the following criteria must apply: new onset of purulent bronchial sputum, temperature: > 38◦ C or < 35.5◦ C, leukocytes: > 10,000/mm3 or < 4,000/mm3 , new or progressive infiltrate in radiograph, onset of symptoms associated with mechanical ventilation; one of following “significant respiratory secretions”: tracheal aspirate: > 106 CFU/ml, bronchoalveolar aspirate: > 104 CFU/ml, protected brush catheter: > 103 CFU/ml, (if the CFU count was too low, a positive blood culture coinciding was required to fulfill this criterion)
Average APACHE II score: o: 13.7, c: 13.8
o: 9.9, c: 9.5
Discussion
Lorente Spain et al. [20]
Country
Table 1 Continued
Type of ICU (no. of patients)
Type of closed suctioning system
Hours of closed system use
Pneumonia at admission excluded
No. of open Criteria for diagnosis nosocomial of ventilationand closed associated pneumonia suctioning procedures per day
Severity of illness
Average no. of days of mechanical ventilation
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Closed suctioning systems encompass some advantages in handling compared to open systems. When closed systems are in use, mechanical ventilation may be continued without interruption, positive end-expiratory pressure may be maintained [22, 23], and the risk of infection for medical staff (e.g., by Mycobacterium tuberculosis positive patients) is reduced [24]. In addition, the risk of introducing new pathogens from external sources into the patient’s respiratory system is minimized with closed systems because the system is disconnected only once a day or less. On the other hand, open suctioning systems use a new and sterile catheter each time while the catheter of the closed system is reused several times within the 24-h period of use. One may speculate that contaminating bacteria from previous suction procedures would multiply on contaminated catheters of closed suctioning systems over time. The question of whether prolonged use of closed suctioning systems leads to significant growth of bacteria on the catheter over longer periods that are introduced in the patient’s respiratory system at later suctioning procedures is controversial; hence the importance of contamination of closed suctioning system remains unclear. We found evidence that bacterial growth on the catheter surface occurs [25] while others studies have not reported increased numbers of pathogens [26]. To our knowledge there is as yet only a single RCT that has compared different use periods of closed suctioning systems with respect to the outcome of VAP [27]. Unfortunately, only two of the studies included in this meta-analysis stated explicitly that the specimens for microbiological testing were taken by a new and sterile closed suction system to exclude a possible bias for subsequent diagnosis of pneumonia [12, 14]. Therefore it remains unknown how many false-positive respiratory tract infections were diagnosed among patients with closed suctioning systems in the other studies due to heavy tracheal secrete contamination from reused catheters. Nine studies were included in our analysis, and only one of these reported a significant result (in favor of the closed suctioning system) [17]. In this study the endotracheal tube inserted initially was replaced after 12 h of use by a different kind of endotracheal tube to determine microbiological cross-contamination due to previous incorrect tube placement or lack of maintenance of tube positioning. However, tubes were replaced in both patient groups (open and closed suctioning) and therefore is unlikely to have had an impact on this outcome of VAP [17]. None of the patients included in this meta-analysis had symptoms of respiratory tract infection at the time of admission, and criteria for the definition of later pneumonia differed only marginal between the studies. The exact number of suctioning procedures cannot be evaluated because this was performed when “needed clinically” in addition to a designated regime in most
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Table 2 Relative risk (RR) of ventilation-associated pneumonia in different suctioning systems: total no./no. with pneumonia (%)
Deppe et al. [12] Johnson et al. [13] Adams et al. [14] Combes et al. [15] Zeitoun et al. [16] Rabitsch et al. [17] Topeli et al. [18] Lorente et al. [19] Lorente et al. [20] Total a DerSimoniand–Laird
Open
Close
RR
95% CI
11/38 (29%) 10/19 (53%) 0/10 (0%) 9/54 (17%) 11/24 (46%) 5/12 (42%) 9/37 (24%) 42/233 (18%) 31/221 (14%) 128/648 (20%)
12/46 (26%) 8/16 (50%) 0/10 (0%) 4/50 (8%) 7/23 (30%) 0/12 (0%) 13/41 (32%) 43/210 (20%) 33/236 (14%) 120/644 (19%)
0.90 0.95 (Undefined) 0.48 0.66 0.09 1.30 1.14 1.00 0.95a
0.45–1.81 0.50–1.82 – 0.16–1.46 0.31–1.41 0.006–1.48 0.63–2.69 0.78–1.66 0.64–1.58 0.76–1.18
method for pooled relative risks ([14] is excluded)
studies. As shown in Table 1, the patients included in different studies were cared for in different kinds of ICUs such as medical, surgical, trauma, or neurosurgical. This may contribute to the range of infection rates that has been reported, for example, from the German Nosocomial Infections Surveillance Systems (for reference data see http://www.nrz-hygiene.de/dwnld/referenz_its_.pdf). In addition, there is also wide variance in VAP rates even within the single kinds of ICU. Because the majority of studies did not show significant results by themselves, we believe that major publication bias seems less likely in our analysis, although the funnel plot revealed publication bias to some extent (data not shown). As with most single observation studies, this meta-analysis also failed to ascertain a significant advantage of either suctioning system. However, one must bear in mind that these results are based on 1,292 patients. At a VAP incidence of 20% we would only have been able to detect a significant reduction in the relative risk of at least 27%, but the true potential of pneumonia prevention by one specific system may be less than this and could become evident if data on more patients become available. Until then the choice of suctioning system should be based on convenience in handling, cost-effectiveness, and the individual patient’s disease. Further studies with greater numbers of patients are needed to determine whether the choice of suctioning system affects the rate of nosocomial pneumonia at a relative risk reduction of less than 27%. Whether ecological (waste) and economical (cost) evaluation favors one system or the other depends principally upon the frequency of suctioning processes of
open systems and length of periods that closed systems are used [7, 11, 13, 19, 28, 29]. The maximum period that closed systems can be used safely is not yet known, although there is accumulating evidence that they may not need to be changed routinely [7]. Kollef et al. [27] reported that there was no increased risk of pneumonia (relative risk 0.99, 95% CI 0.66–1.50) in ventilated patients if closed suctioning systems are not changed at all during patient’s ICU stay unless clinically indicated. This reduced the cost of the closed suctioning system from U.S.$11,016 (routine changes in the in-line suctioning system; 263 patients) to U.S.$837 (no routine changes; 258 patients) [27]. Recent cost calculations by Lorente et al. [20] reveal cost-effectiveness for closed suctioning systems that are not changed regularly as soon as the time of the patient’s mechanical ventilation exceeds 4 days. One major benefit of closed suction catheters may be a decreased bacterial contamination of caregivers. This factor cannot be investigated in a RCT design. This is why additional trials should be carried out using closed suctioning systems only and comparing the rate of nosocomial pneumonia before and after. This would exclude possible contamination of health care worker’s hands due to intermittent open suctioning of other patients. Although there is little benefit for the individual patient, there might be some potential to reduce the burden of bacterial transmission by using closed suctioning systems. This could be of importance particularly if there is a high prevalence of multidrug resistant pathogens such as methicillin-resistant Staphylococcus aureus and other multiresistant Gram-negative bacteria.
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