Ventilator-associated pneumonia in children: evaluation of clinical pulmonary infection score in monitoring the course of illness

In the past few years the clinical pulmonary infection score (CPIS) has been purposed as a diagnostic tool in ventilator-associated pneumonia (VAP). The CPIS incorporates five variables: temperature (T°C), white blood cells (WBC), tracheal secretions, pO₂/FiO₂ and RX. The range of CPIS is from 0 to 12 and its positive predictive value (PPV) has been found >90% at a cutoff point ≥6. Recently, the CPIS was purposed in order to monitor the course of VAP and the efficacy of therapy.

Objective

To evaluate the CPIS in diagnosis of and monitoring the course of illness in children with VAP.

Design

A retrospective observational study.

Setting

Pediatric ICU in a national children hospital.

Patients

Forty consecutive children admitted to the pediatric ICU and mechanically ventilated > 48 hours were observed for developing VAP between 2002 and 2003. In patients who did not develop VAP the study was suspended at weaning time. Fifteen patients were enrolled who developed VAP; the diagnosis was based on microbiological data (quantitative cultures of bronchoalveolar lavage [BAL] fluids or mini BAL).

Data collection

CPIS was collected 48 hours before diagnosis of VAP, at diagnosis, and daily for the first week. In all patients were evaluated the mean PAW, positive end expiratory pressure (PEEP), PO₂/FiO₂, RX score, PCR, WBC, T°C and number of bronchial suctionings/day. We have also evaluated the influence of each parameter of CPIS on the final score. Data were analysed with the Student t test (P < 0.05*), chi square (P < 0.05**) and univariate analysis (correlation coefficient R²***).

Results

In our population the incidence of VAP was 37% (15/40 patients) with mortality 27% (four patients). The mean CPIS value at the time of diagnosis was statistically higher than 48 and 24 hours before in all patients (4.9 ± 0.8 vs 7.5 ± 1.5, P < 0.05); in 14/15 patients it was ≥6 (PPV 93%). At day 3 after diagnosis the population was divided into two groups: patients with CPIS ≥ 6 (group 1, n = 5) and patients with CPIS < 6 (group 2, n = 10). At this time between the two groups were reported statistically significant differences in PEEP (10.5 ± 1 vs 5.6 ± 2.7, P < 0.05*), PAW max (27.5 ± 6.6 vs 14.7 ± 8.6, P < 0.05*), pO₂/FiO₂ (145 ± 10 vs 282 ± 20, P < 0.05*), PCR reduction > 30% (20% vs 50% of patients, P < 0.05**) and microbiological positivity (80% vs 20%, P < 0.05**). pO₂/FiO₂ increases significantly in group 2 (P < 0.05*) and univariate analysis revealed that only pO₂/FiO₂ is related to the CPIS score(R²*** 0.77***); WBC, T°C, number of suctioning/day and RX score are not related. All patients with CPIS < 6 survived whereas 80% of patients with persistently high CPIS after 72 hours from diagnosis of VAP died. The analysis of the MSOFA score revealed significant differences in circulatory (P < 0.05*) and respiratory (P < 0.05*) scores between those who died and survivors at day 3 and later after diagnosis of VAP.

Conclusions

CPIS had an elevated PPV in diagnosis of VAP (93%), and is an early predictor of poor outcome in patients with VAP and allows a good monitoring of the course of illness.