Current issues of ACP Journal Club are published in Annals of Internal Medicine


Therapeutics

Decreasing the incidence of ventilator-associated pneumonia

ACP J Club. 1991 Sept-Oct;115:35. doi:10.7326/ACPJC-1991-115-2-035


Source Citation

Pugin J, Auckenthaler R, Lew DP, Suter PM. Oropharyngeal decontamination decreases incidence of ventilator-associated pneumonia. A randomized, placebo-controlled, double-blind clinical trial. JAMA. May


Abstract

Objective

To evaluate the effectiveness of oropharyngeal decontamination with nonabsorbable antibiotics in reducing ventilator-associated pneumonia.

Design

Randomized, double-blind, placebo-controlled trial, beginning within 24 hours of intubation and continuing for 12 days or until extubation or death.

Setting

Surgical intensive care unit.

Patients

Of 850 admissions, 79 high-risk adults (including patients with trauma, sepsis, or vital organ failure after gastrointestinal bleeding or cardiovascular surgery) with predicted intubation for ≥ 24 hours and mechanical ventilation were randomized. 27 patients (34%) were excluded from the study for early extubation or early death; patients were comparable in the 2 groups.

Intervention

25 patients had 15 mL nonabsorbable antibiotic solution (150 mg polymyxin B sulfate, 1 g neomycin sulfate, 1 g vancomycin hydrochloride in 60 mL 5% dextrose [PNV]) syringed into the retropharynx 6 times daily or held in the mouth and then swallowed. 27 patients received dextrose placebo. In each group similar numbers of patients received intravenous prophylactic antibiotics (n = 14 and 15).

Main outcome measures

Rectal temperature, blood leukocyte count, purulence and quantity of tracheal secretions, mean arterial oxygen tension/inspiratory fraction of oxygen, chest roentgenogram, and microscopic examination and aerobic cultures of tracheobronchial aspirates were combined into a clinical pulmonary infection score (CPIS) that was calculated at least every second day. Ventilator-associated pneumonia was defined as a CPIS score of ≥ 7 for ≥ 3 consecutive days.

Main results

7 patients in each group died from multiple organ failure and either sepsis or the respiratory distress syndrome, or cerebral or cardiac failure. Ventilator-associated pneumonia occurred in 78% of the placebo group and 16% of the PNV group {95% CI for difference, 41% to 83%} (P < 0.001). The mean baseline CPIS was approximately 5 for each group. In the placebo group it rose to a mean of 7.3 ± 0.4 (SE) after 12 days, but remained stable at 4.8 ± 0.9 for the PNV group (P < 0.001); differences became significant after 4 days. The PNV group had fewer purulent tracheobronchial secretions, a lower incidence of localized infiltrate on chest roentgenogram, and higher arterial oxygen tension values than the placebo group.

Conclusion

Oropharyngeal decontamination with PNV reduced ventilator-associated pneumonia in severely ill patients requiring long-term intubation.

Source of funding: Not stated.

Address for article reprint: Dr. P.M. Suter, Division of Surgical Intensive Care, University Hospital of Geneva, CH-1211 Geneva 4, Switzerland.


Commentary

Ventilator-associated pneumonia in critically ill or injured adults is an important cause of morbidity and mortality. This well-designed study adds to the evidence suggesting that local antibiotic decontamination of the oropharynx decreases ventilator-associated pneumonia in high-risk patients. However, no benefit was reported for the clinically important measures of mortality, duration of mechanical ventilation, or intensive care unit stay. Whether this reflects a true lack of benefit or an inadequate number of study subjects cannot be determined without a larger study.

The benefit of oropharyngeal decontamination was independent of systemic prophylactic or therapeutic antibiotic therapy given to some patients. Group inequality in pneumonia resulting from aspiration of nasogastric tube feedings appeared an unlikely source of bias, because feedings were administered to a similar proportion of patients in each group, and the investigators did not observe any clinically apparent episodes of tube-feeding aspiration.

Fungal colonization of the lower respiratory tract occurred more often in antibiotic-treated patients. This should serve as a caution to physicians in whose patients fungal pneumonia is a frequent problem. Although antibiotic resistance was not observed, the authors appropriately warn of this possibility and its adverse consequences. Restricting oropharyngeal decontamination to carefully selected high-risk patients and minimizing the duration of therapy will probably help reduce the emergence of resistant organisms. However, identifying which patients are at sufficiently high risk to benefit from oropharyngeal decontamination and determining the optimal duration of therapy will require additional investigation.

These study results suggest that careful use of oropharyngeal decontamination therapy is a logical and effective choice for preventing nosocomial pneumonia in high-risk patients undergoing mechanical ventilation. If additional experience confirms that infectious complications caused by fungi or resistant bacteria are not increased, oropharyngeal decontamination therapy will probably be used more widely.

Michael H. Zaroukian, MD, PhD
Michigan State University College of Human Medicine East Lansing, Michigan, USA