Original Articles
Ventilator-associated pneumonia: Incidence, risk factors, outcome, and microbiology*

https://doi.org/10.1053/jcan.2003.4Get rights and content

Abstract

Objective: To determine the incidence, risk factors, outcome, and pathogens of ventilator-associated pneumonia (VAP) in a cardiac surgical intensive care unit (ICU). Design: Prospective study. Setting: Escorts Heart Institute and Research Centre, New Delhi, India. Participants: Nine hundred fifty-two consecutive patients undergoing cardiac operations who received intermittent positive-pressure ventilation (IPPV). Interventions: All patients were assigned into VAP (n = 25) and non-VAP (n = 927) groups. Measurement and Main Results: Risk factors and other variables were analyzed with univariate and multivariate analysis. Of the 952 patients studied, 25 (2.6%) had VAP. On univariate analysis, significant risk factors were emergency surgery, chronic obstructive pulmonary disease (COPD), reintubation, coma, steroid treatment, intra-aortic balloon counterpulsation (IABC), enteral feedings, tracheostomy, acute physiology, age, and chronic health evaluation (APACHE II) score, prior antibiotics, and IPPV hours. On multivariate analysis, IPPV hours (153.75 ± 114.44 v 19.65 ± 7.99; p < 0.001) and steroids (20% v 0%; p < 0.001) were independent predictors of VAP. The most common pathogens isolated were Pseudomonas aeruginosa (22), Escherichia coli (10), Klebsiella pneumoniae (4), Staphylococcus species (4), and Acinetobacter species (2). The mortality rate in VAP was 16% as compared with 0.2% in non-VAP cases (p < 0.001). Conclusion: These data suggest that by univariate analysis the risk factors for VAP were emergency surgery, COPD, reintubation, coma, steroid treatment, IABC, enteral feedings, tracheostomy, APACHE II score, prior antibiotics, and IPPV hours. On multivariate analysis, only IPPV hours and steroids were independent predictors of VAP. Pseudomonas aeruginosa is the most common pathogen associated with VAP, and the mortality is increased with VAP. Copyright 2003, Elsevier Science (USA). All rights reserved.

Section snippets

Materials and methods

Approval of the institutional review board and informed consent from the patient were obtained for this prospective study conducted at Escorts Heart Institute and Research Centre between July 27, 2001, and October 31, 2001, to determine the incidence, risk factors, outcome, and pathogens of VAP in the cardiac surgical ICU. During this period, 952 adult patients who were undergoing cardiac operations and were admitted to the ICU on IPPV were included in this prospective study. They consisted of

Results

Of 952 patients in the study, 25 (2.6%) had VAP. The mean interval between admission to the ICU and the diagnosis of VAP was 4.5 ± 2.8 days. The median interval was 4 days. More than 90% of VAP cases occurred within 10 days of admission to the ICU.

Table 1 shows the results from the univariate analysis for 8 variables that were not significantly associated with VAP.

. Comparison of VAP and non-VAP cases (univariate analysis)

VariableVAP (n = 25)Non-VAP (n = 927)p Value
Age (y)59.7 ± 12.756.5 ± 10.7NS

Discussion

The authors investigated the incidence, risk factors, outcome, and pathogens of VAP in the cardiac surgical ICU. The estimated prevalence of nosocomial pneumonia in intensive care units ranges from 10% to 65% with mortality rates of 13% to 55%.1 Nosocomial pneumonia was diagnosed in 25 (2.6%) of the 952 patients in this study. The incidence of 2.6% in cardiothoracic patients is comparable to that reported in another study.6 The supine position of mechanically ventilated patients increases the

Acknowledgements

The authors thank S. Shekhawat for statistical analysis and R. Mathew for secretarial assistance.

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    *

    Address reprint requests to Yatin Mehta, MD, DNB, FRCA, FAMS, Department of Anaesthesiology, Escorts Heart Institute and Research Centre, New Delhi 110 025, India. E-mail: [email protected]

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