Continuous aspiration reduced ventilator-associated pneumonia
ACP J Club. 1995 May-June;122:72. doi:10.7326/ACPJC-1995-122-3-072
Vallés J, Artigas A, Rello J, et al. Continuous aspiration of subglottic secretions in preventing ventilator-associated pneumonia. Ann Intern Med. 1995 Feb 1;122:179-86.
To evaluate the effectiveness of continuous aspiration of subglottic secretions in preventing ventilator-associated pneumonia among patients in the intensive care unit (ICU).
Single-blind, randomized controlled trial with follow-up until death or discharge from the ICU.
ICU in Spain.
153 consecutive eligible patients (mean age 63 y, 54% men) who were admitted to the ICU, required intubation in the ICU or the emergency department, and were expected to require mechanical ventilation for ≥ 72 hours. Exclusion criteria were tracheostomy tube or development of pneumonia or death ≤ 72 hours after mechanical ventilation was begun.
Patients were intubated with an endotracheal tube and assigned to continuous aspiration through the additional lumen of the endotracheal tube (n = 76) or to usual care in which the lumen was closed (n = 77). All patients received stress ulcer prophylaxis with sucralfate but did not receive selective decontamination or antibiotic prophylaxis.
Main outcome measures
Mortality, development of pneumonia, duration of ventilation, and length of stay in the ICU. In most cases, diagnosis of suspected pneumonia was confirmed by a positive protected specimen brush culture or by a positive bronchoalveolar lavage culture.
Fewer patients in the continuous aspiration group developed ventilator-associated pneumonia compared with the usual care group (Table). The difference was attributable to the reduction in the number of patients diagnosed with pneumonia (caused by Haemophilus influenzae and gram-positive cocci) during the first week after intubation. The groups did not differ for mortality in patients with pneumonia (50% vs 52%). Overall, the group receiving continuous aspiration did not differ from the control group for median duration of ventilation (13 vs 11 d, P > 0.2), length of ICU stay (22 vs 19 d, P > 0.2), or crude mortality (39.5% vs 36.4%, P > 0.05).
Continuous aspiration of subglottic secretions reduced the incidence of ventilator-associated pneumonia among patients in the intensive care unit but did not affect mortality, duration of ventilation, or length of stay.
Source of funding: In part, Social Security Health Investigation Fund of Spain.
For article reprint: Dr. J. Vallés, Intensive Care and Microbiology Departments, Hospital de Sabadell, Parc Taulí s/n 08208, Sabadell, Barcelona, Spain.
Table. Continuous aspiration of subglottic secretions vs usual care for prevention of ventilator-associated pneumonia among patients in the intensive care unit*
|Outcome (follow-up to death or discharge from intensive care unit)||Continuous aspiration||Usual care||RRR (95% CI)||NNT (CI)|
|Ventilator-associated pneumonia||18%||33%||43% (1 to 68)||8 (4 to 518)|
*Abbreviations defined in Glossary; RRR, NNT, and CI calculated from data in article.
This study by Vallés and colleagues is one of the few randomized controlled trials suggesting the effectiveness of a preventive measure for ventilator-associated pneumonia, and the second trial dealing with subglottic secretions drainage (1, 2). This trial shows that continuous aspiration may reduce the incidence of ventilator-associated pneumonia by almost half or delay its onset. Although investigators were not blinded to treatment allocation and an intention-to-treat analysis was not done, one strength of this study is that the diagnosis of pneumonia was ascertained using specific sampling techniques.
Similar to the results of many studies of "selective digestive tract decontamination," however, none of the major outcome measures of prophylaxis was affected by the maneuver. These results contradict those from epidemiologic studies that showed increased mortality or length of stay in patients with nosocomial pneumonia. This lack of effect of continuous aspiration on outcome may be related to the unexpected (and unexplained) finding that only "early-onset" pneumonias (i.e., occurring within the first few days of an ICU stay and caused by common respiratory pathogens) were prevented by continuous aspiration. Although infection caused by these pathogens is associated with low morbidity, their influence on outcome may vary according to the population studied.
Another expected benefit of the reduced rates of ventilator-associated pneumonia is a reduction of total antibiotic use and costs, which in turn may influence antibiotic susceptibility of organisms causing infections; unfortunately, data on antibiotic use were not provided.
Despite these shortcomings, the current evidence supporting subglottic secretions drainage is more powerful than what is currently available for many common preventive measures of ventilator-associated pneumonia. This supports the addition of this measure to the current list of other simple recommendations (such as maintaining patients in a semi-recumbent position). Further evaluation of the effect of this measure, however, is needed.
Christian Brun-Buisson, MD
Hôpital Henri Mondor - Université Paris XIICréteil, France
1. Mahul P, Auboyer C, Jospe R, et al. Prevention of nosocomial pneumonia in intubated patients: respective role of mechanical subglottic secretions drainage and stress ulcer prophylaxis. Intensive Care Med. 1992;18:20-5.