Abstract

Objectives: To determine incidence, related factors, outcome, bacterial organisms and their sensitivity patterns with regard to ventilator-associated pneumonia (VAP) in children.

Setting: Level III PICU of a tertiary care center.

Design: Prospective cohort study.

Methods: Children in the age group of 1 month to 15 years, admitted to the pediatric intensive care unit requiring ventilatory support (V.I.P.BIRD infant-Pediatric ventilator) for at least 48 h. Clinical criteria used to define VAPs were the same as used by and Elward et al. and Salata et al.

Results: Forty patients met the inclusion criteria and 8 (20%) had VAP. The risk factor significantly related with development of VAP was the use of H2 blockers (Ranitidine) for >2 days. All other related factors were not significantly related to occurrence of VAP.

Conclusion: Use of H2 blockers (Ranitidne) is associated with higher incidence of VAP in children.

Introduction

VAP (ventilator-associated Pneumonia) is the specific type of Nosocomial Pneumonia (NP) developing in patients with acute respiratory failure who have received mechanical ventilation for at least 48 h [1]. The epidemiology of VAPs are well described in adults, but few data exist for pediatric patients, particularly with respect to risk factors and outcomes, such as attributable morbidity and mortality and there is no such study available from northern India so this was a much needed study [2–4].

Subject and Methods

This study was conducted over a period of 18 months in the Pediatric Intensive Care Unit(PICU) of Dayanand Medical College and Hospital, a tertiary care teaching hospital in Ludhiana, Punjab, India. The study group included children in the age group of 1 month–15 years ventilated for >48 h, admitted in PICU. Neonates and children with pre-existing pneumonias or having lung infiltrates due to atelectasis, pulmonary embolism, Acute Respiratory Distress Syndrome and Congestive Cardiac Failure were excluded from the study.

Clinical criteria to define VAP used in this study were based on the work of Elward et al. [5] and Salata et al. [6] which included the following two essential criteria:

  • Evidence of new or persistent radiographic infiltrates (not otherwise explained) after 48 h or more of PICU stay.

  • Tracheal aspirates or endotracheal tube tip culture showing growth of potential pathogens, e.g. aerobic bacteria.

In addition to any two of the following three criteria:

  • Temperature >38°C or 100.4°F

  • Leucocytosis (total leucocyte count >12 000 mm−3)

  • Purulent tracheal aspirates (>25 white blood cells/high power field on Gram stain).

Patients after 48 h of ventilatory support fulfilling two essential or any two of the three other criteria were labeled as cases of VAP. The roles of viruses, fungi and anaerobic organisms in the development of VAP were not studied. These patients were subjected to detailed examination and investigations. Relevant information was duly recorded and analyzed by comparing means. Student t and Fisher exact test (wherever applicable) were applied for calculating p-values using the Statistical Package for Social Sciences Version 10 (SPSS, Chicago, IL, USA).

Results

Forty patients met the inclusion criteria and formed the study group. Eight patients fulfilled VAP criteria and formed VAP group and the remaining 32 patients non-VAP group. All variables were compared by dividing patients into VAP and non-VAP group.

Incidence of VAP was 20% in PICU of this region. The mean age for the study group was 3.30 ± 4.30 years with 40% infants. Of the patients in the VAP group, 37.5% were between 1 month and 1 year (Mean age = 3.56 ± 3.95 years). Risk factors studied and compared between two groups were shock and altered sensorium on admission, re-intubations (if done and number of times), central line insertions, transfusions (blood and blood products), feeding on ventilator, use of intravenous steroids (≥2 day on ventilator), use of H2 blockers viz ranitidine (≥2 days on ventilator), transport out of PICU. Escherichia coli constituted 50% of the organisms in the VAP group followed by Staphylococcus aureus (25%) and Acinetobacter (25%).

Discussion

VAP is an important problem in PICU of developing countries. Diagnosis of VAP may differ significantly, depending on the methods used. Bronchoscopic diagnostic methods are not routinely used because of technical difficulties and complications [7].

The incidence of VAP in our study was 20%. Incidence of pediatric VAP as mentioned in western literature varies from 5.1% to 33% [8–10].

Out of the various variables studied as mentioned earlier, the only risk factor significantly associated with VAP was the use of H2 blockers viz ranitidine (≥2 days) (χ2 = 5.030, p = 0.025).

The results of several studies analyzed by Chastre et al. [11] have indicated lower rates of pneumonia among patients who were given a gastroprotective agent (sucralfate) rather than agents that neutralize gastric secretions (antacids) or block gastric acid secretion (H2 blockers). We only used ranitidine in our patients wherever required. IV ranitidine was given for ≥2 days in 5 (62.5%) patients in the VAP group and in 7 (21.88%) patients in the non-VAP group in our study with a statistically significant difference between the two groups, indicating that VAP is related to H2 blocker use.

In VAP group, 6 (75.00%) subjects received transfusion and in non-VAP group 20 (62.50%) received transfusion. These values following comparison of both groups were not statistically significant in our study. Comparing the mean number of transfusions in VAP group (2.50 ± 2.67) with the non-VAP group (0.94 ± 1.01), was also not statistically significant (d = 1.625, p = 0.145).

Literature on Adult VAP mentions >4 U of blood product transfusion as an intervention factor linked with VAP [2]. In Pediatrics, one such study on VAP where 20 patients with VAP were studied, VAP was linked with the total number of transfusions received [5]. Whether these transfusions were received before or after infection was not noted.

Mean duration of ventilation stay in VAP group was 7.13 ± 4.16 days compared to the non-VAP group, which was 4.78 ± 2.95 days and the difference between the two groups was not significant (t = 1.86, p = 0.072). Published literature mentions the length of stay on the ventilator of >2 days as a risk factor for VAP. Mean duration of hospital stay in the VAP group was 17.5 ± 10.13 days as compared with the non-VAP group which was 10.38 ± 8.02 days and the difference between two groups was significant (t = 2.13, p = 0.039) which is in accordance with many published studies [2, 5]. This can be explained on the fact that the patients who develop VAP require longer duration of intravenous antibiotics, which prolongs the length of their hospital stay.

In the VAP group 6 (75%) patients improved out of 8 patients whereas in non-VAP group, out of 32 patients, 10 (31.25%) improved. This was statistically significant (p = 0.0238). Mortality in VAP group was 12.5% and in non-VAP group was 36.36%, which was not statistically significant. It can be concluded from these findings that VAP significantly increases morbidity but not mortality.

Limitations of the study were that the study group was small, as the study was done only on one ventilator and was based on strict guidelines with a fixed time period. Also, multiple episodes of VAP were not studied. In conclusion, it can be said that there is a paucity of literature on VAPs in children especially in developing countries. Multicentre studies with larger sample sizes are needed for ascertaining the risk factors, morbidity and mortality, associated pathogens and management strategies in future.

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