Relationship Between Intra-Abdominal pressure and microaspiration of gastric contents in critically ill mechanically ventilated patients

The relationship between increased intra-abdominal pressure (IAP) and microaspiration of oro-gastric content in mechanically-ventilated patients has not yet been established. Microaspiration is proposed as one of the causes of ventilator-associated pneumonia (VAP). We aimed to investigate whether mechanically-ventilated patients with increased IAP present evidence of lung microaspiration by assessing pepsin levels in bronchial secretions and evaluated the relationship between pepsin and VAP. 68 mechanically-ventilated patients and 10 control subjects were recruited from an academic ICU in Greece. IAP, pH, pepsin and total protein levels, in bronchial secretions, were assessed within 14 days. Patients underwent assessment for timely VAP diagnosis based on clinical, radiological and laboratory criteria. Pepsin and total protein levels were significantly elevated in patients compared to controls. Pepsin values correlated significantly with IAP (r = 0.61, ***p < 0.001). Multivariate regression analysis showed that IAP was an independent risk factor for increased pepsin values in bronchial secretions [OR95%CI 1.463(1.061–1.620), *p = 0.014]. Pepsin values were higher in patients with VAP, while IAP was independently associated with VAP. There was an indication towards increased VAP in patients with increased pepsin. In conclusion, our results show that pepsin in bronchial secretions may be elevated when IAP is increased, indicating microaspiration and potentially VAP.