Clinical pulmonary infection score study

Purpose: To prospectively study utility of the clinical pulmonary infection score (CPIS) in the diagnosis of ventilator associated pneumonia (VAP). Methods: We prospectively studied patients admitted to medical, surgical, coronary and neurology intensive care units at a tertiary hospital for a period of 60 days. All patients mechanically ventilated ≥ 48 hours were enrolled, except those diagnosed with pneumonia prior to 48 hours. Daily CPIS based on temperature, leukocyte count, tracheal secretions, PaO2/FiO2 ratio, endotracheal aspirate culture and chest x-ray were performed. Patients suspected of having VAP or CPIS ≥ 6 had non-bronchoscopic or bronchoscopic bronchoalveolar lavage (BAL). Subjective clinical suspicion was based on chart review or physician interview. Criteria for diagnoses of VAP included cell count and differential, presence of intracellular organisms and quantitative cultures of the BAL fluid. Only first episodes of VAP, clinical suspicion or CPIS ≥ 6 were analyzed. Results: 56 patients were prospectively enrolled in the study. Additional 3 patients refused to participate in the study. 19 patients met criteria for diagnoses of VAP. Only 1 patient had BAL on the basis of CPIS ≥ 7, and met criteria for VAP despite lack of clinical suspicion. Results are tabulated below. (* includes score calculated if endotracheal aspirate results were not available at the time of clinical suspicion) Conclusions: A CPIS≥7 has specificity comparable to subjective clinical suspicion with a much lower sensitivity. A complete CPIS requires endotracheal aspirate which is usually done only in response to clinical suspicion. Therefore the use of CPIS is best analyzed as a sequential test with clinical suspicion and the score without the results of endotracheal aspirate is most appropriate. In this setting a CPIS ≥7 increased probablity of VAP from 80.6% to 96%, but only in (3/19) 15.8% cases. Conversely a CPIS<7 only decreased the probablity from 80.6% to 78.3%. Clinical Implications: In the diagnoses of VAP, routine use of CPIS has no benefit due to low sensitivity. Even when used in conjunction with clinical suspicion it offers limited benefit. Positive Negative Sensitivity Specificity Likelihood Likelihood (%) (%) ratio ratio Clinical suspicion 89.5 89.2 8.3 0.12 CPIS≥6* 26.3 91.9 3.3 0.8 CPIS≥7* 15.8 97.3 5.8 0.87 CPIS≥7 36.8 97.3 13.6 0.65.