Abstract
BackgroundMicroaspiration of gastric and oropharyngeal secretions is the main mechanism of entry of bacteria into the lower respiratory tract in intubated critically ill patients. The aim of this study is to determine the impact of enteral nutrition, as compared with parenteral nutrition, on abundant microaspiration of gastric contents and oropharyngeal secretions.MethodsPlanned ancillary study of the randomized controlled multicenter NUTRIREA2 trial. Patients with shock receiving invasive mechanical ventilation were randomized to receive early enteral or parenteral nutrition. All tracheal aspirates were collected during the 48 h following randomization. Abundant microaspiration of gastric contents and oropharyngeal secretions was defined as the presence of significant levels of pepsin (> 200 ng/ml) and salivary amylase (> 1685 UI/ml) in > 30% of tracheal aspirates.ResultsA total of 151 patients were included (78 and 73 patients in enteral and parenteral nutrition groups, respectively), and 1074 tracheal aspirates were quantitatively analyzed for pepsin and amylase. Although vomiting rate was significantly higher (31% vs 15%, p = 0.016), constipation rate was significantly lower (6% vs 21%, p = 0.010) in patients with enteral than in patients with parenteral nutrition. No significant difference was found regarding other patient characteristics. The percentage of patients with abundant microaspiration of gastric contents was significantly lower in enteral than in parenteral nutrition groups (14% vs 36%, p = 0.004; unadjusted OR 0.80 (95% CI 0.69, 0.93), adjusted OR 0.79 (0.76, 0.94)). The percentage of patients with abundant microaspiration of oropharyngeal secretions was significantly higher in enteral than in parenteral nutrition groups (74% vs 54%, p = 0.026; unadjusted OR 1.21 (95% CI 1.03, 1.44), adjusted OR 1.23 (1.01, 1.48)). No significant difference was found in percentage of patients with ventilator-associated pneumonia between enteral (8%) and parenteral (10%) nutrition groups (HR 0.78 (0.26, 2.28)).ConclusionsOur results suggest that enteral and parenteral nutrition are associated with high rates of microaspiration, although oropharyngeal microaspiration was more common with enteral nutrition and gastric microaspiration was more common with parenteral nutrition.Trial registrationClinicalTrials.gov, NCT03411447. Registered 18 July 2017. Retrospectively registered.
Highlights
Microaspiration of gastric and oropharyngeal secretions is the main mechanism of entry of bacteria into the lower respiratory tract in intubated critically ill patients
One hundred eighty-two patients were included in the NUTRIREA2 study in the 13 centers participating in the ancillary study from February through June 2015, and 151 (84%) patients were included in the ancillary study
The estimated sample size was not reached, because the NUTRIREA2 study was early stopped after the second interim analysis and because the ancillary study was only conducted during a 5-month period
Summary
Microaspiration of gastric and oropharyngeal secretions is the main mechanism of entry of bacteria into the lower respiratory tract in intubated critically ill patients. In the NUTRIREA2 trial on the route of early nutritional support in mechanically ventilated patients with shock, early enteral nutrition was associated with more vomiting but not with increased rates of VAP, compared to early parenteral nutrition [13]. Better understanding of pathophysiology of microaspiration and VAP could be helpful to improve preventive strategies for this infection For this purpose, we planned an ancillary study of the NUTRIREA2 trial to determine the impact of enteral nutrition, compared with parenteral nutrition, on abundant microaspiration of gastric contents and oropharyngeal secretions. Our main hypothesis was that early enteral nutrition, compared to parenteral, might increase the risk of microaspiration of gastric contents in intubated critically ill patients
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