The effect of lactulose in prevention of ventilator associated pneumonia (VAP)

Introduction

Lactulose favourably influences microbial colonisation of colon and may therefore prevent ascending colonisation of the gut and consequently decrease the incidence of VAP. Double blind placebo controlled study using lactulose 4 × 15 ml daily or saline given into the stomach for prevention of VAP was performed in our ICU during 1999-2000.

Materials and methods

Forty-eight patients without pulmonary infiltrates and mechanically ventilated for < 24 hours entered the study. Gastric, oral and tracheal aspirates and rectal swabs were taken for semiquantitive analysis within 24 hours and in 3 days intervals thereafter up to 21 days of ICU stay. For aspirates, the amount of pathogens > 10⁵/ml was considered significant. Metoclopramide and sucralfate were used in all patients. Cyclic enteral nutrition was given into the stomach according to standard protocol.

Statistics

Chi-squared and Fisher exact tests were used, P < 0.05 was considered significant.

Results

Thirty-eight patients (15 lactulose – L and 23 placebo – P) stayed in the ICU > 4 days and were further analysed. L and P groups did not differ in age, APACHE II, ICU survival, LOS, ventila-tory and antibiotic days. The frequency of stools was significantly higher in L group. On day 1 gastric aspirates were positive in 1 L and 2 P patients. On day 4 gastric colonisation increased to 4 (27%) and 7 (30%), respectively (NS). During further ICU stay the colonisation remained in range 20–35% and did not differ between the groups. Candida albicans was the most often pathogen isolated. On day 1 tracheal aspirates were positive in 1 (L group) and 3 (P group) patients. Later on the frequency in both groups increased to and remained in the range of 40–75% (NS). VAS was diagnosed in 6 (40%) and 8 (35%) in L and P groups, respectively (NS). In 9 (L) and 12 (P) patients the pathogen was primarily isolated from oral cavity with Pseudomonas aeruginosa and coagulase negative Staphylococcus being the most often pathogens. The consecutive appearance of pathogen in stomach, oral cavity and trachea was clearly present in 2 patients. In further 5 patients the pathogens were isolated on the same day from all three sites.

Conclusions

Lactulose failed to prevent gastric colonisation in patients on mechanical ventilation. The most often source of pathogens in trachea and VAP in our conditions is the oral cavity.

This study was performed with support grant IGA 4072-3