Aerosolized Bronchodilator Use May Increase Risk for Ventilator-Associated Pneumonia
By Deborah Brauser
Medscape Medical News
January 13, 2010 (Miami, Florida) — Aerosolized bronchodilators are independently associated with an increased risk for ventilator-associated pneumonia (VAP) in critically ill patients, according to results from an observational study presented here at the Society of Critical Care Medicine 39th Critical Care Congress.
Lead author Saad Nseir, MD, from the Medical Intensive Care Unit (ICU) at Calmette Hospital, CHRU, in Lille, France, reported during his oral presentation that although bronchodilator use has increased for mechanically ventilated patients, past studies "have suggested that aerosol therapy may promote bacterial colonization of ventilator circuit and subsequent VAP."
"We thought it would be interesting to look more at that aspect, along with other possible side effects of using inhaled therapy," said Dr. Nseir.
For this study, his investigative team enrolled all patients at the Calmette Hospital's ICU over a 1-year period who required intubation and mechanical ventilation for more than 48 hours (n?= 439) and noted any first episodes of VAP.
The investigators used both univariate and multivariate analysis to determine the risk factors for VAP.
Results
At the end of the study, results showed that 137 of 439 patients (31%) developed VAP. Of these, 13% developed early-onset VAP.
The most frequent bacteria found was Pseudomonas aeruginosa (42%), followed by Acinetobacter baumannii (13%) and Enterobacter species (9%).
Significant differences (P?< .05) were found on univariate analysis between patients with and without VAP. These risk factors included the Simplified Acute Physiologic Score (SAPS)?II (54?± 16 for those with VAP vs 48?± 20 for those without VAP), transfer from other wards (71% vs 60%, respectively), aerosolized salbutamol use (49% vs 34%, respectively), intravenous salbutamol use (24% vs 12%, respectively), corticosteroid use (78% vs 62%, respectively), stress ulcer prophylaxis (94% vs 86%, respectively), red blood cell transfusion (62% vs 40%, respectively), and duration of mechanical ventilation before VAP (18?± 16 vs 13?± 12 days, respectively).
Independent risk factors for VAP found by multivariate analysis included aerosolized salbutamol use (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.1?- 2.6; P?= .012), SAPS?II (OR, 1.01 per point; P?= .031), and red blood cell transfusion (OR, 2.05; 95% CI, 1.3?- 3.1; P?= .001).
"Patients with VAP also had a significantly longer ICU length of stay and significantly higher mortality," reported Dr. Nseir.
"I think the number?1 takeaway message is to avoid using inhaled therapy routinely in mechanically ventilated patients and to wait for stronger evidence of the benefit of these therapies," he advised.
"It would be interesting to now do a randomized study comparing inhaled therapy with bronchodilators against [intravenous] bronchodilators and to see the side effects of each," Dr. Nseir added.
Limitations of this study include its observational design, the fact that it was conducted at only 1 center, and the fact that the bronchodilator prescriptions were not protocolized.
More Information Needed
"I think one of the most notable parts about this study is the high rate of [VAP] in their ICU; 31% is extraordinarily large," said session comoderator Sean Townsend, MD, professor of medicine at the University of Massachusetts in the Department of Pulmonary Critical Care, in Worcester.
Dr. Townsend, who was not involved with this study, said that many centers often go a year at a time without any cases of VAP. "That said, perhaps this was a good population in which to study inhaled bronchodilators and their association with VAP. Or perhaps it's an anomaly. Often, the ICUs in Europe have patients who are more critically ill than in the United States and perhaps the higher VAP rate found in this study corresponds to the higher acuity of illness there."
He said that he was also concerned that the study did not look at the need for the bronchodilator and only used 1 type for all patients. "There are times when bronchodilator use is called for, such as with [chronic obstructive pulmonary disease] patients who are bronchospastic and [who have poor] compliance?.?.?. on the ventilator. So the necessity to use it may overwhelm the risk for increased VAP."
When asked why he thought this was selected as one of the Top?100 Abstracts at the event, Dr. Townsend said: "This is a novel study. Only one other study previously isolated this risk factor. We now need a prospective study with much larger numbers, and some assessment should be made as to whether a patient has a comorbidity that justifies the use of the bronchodilator."
Dr. Nseir and Dr. Townsend have disclosed no relevant financial relationships.
Society of Critical Care Medicine (SCCM) 39th Critical Care Congress: Abstract?10. Presented January?10, 2010.
