233 Presence of Bile Acids and Pepsin in Saliva and Broncho-Alveolar Lavage of Patients With Idiopathic Pulmonary Fibrosis Is Associated to Increased Severity of Lung Disease

Abstract

Background: Gastroesophageal reflux (GER) and microaspiration of gastric contents has been proposed as an important mechanism in the pathogenesis of ventilator associated pneumonia (VAP) but properties of GER in patients receiving acid suppresive therapy in intensive care unit (ICU) and its effect on VAP and respiratory function in these patients is not elucidated. Aim: This study aims to assess the association between GER and VAP by defining the differences between VAP and non-VAP patients in ICU in terms of proximal extension and chemical properties of GER assessed by 24 hour combined esophageal intraluminal electrical impedance/pH measurements. We also aimed to study the association of impedance/pH values with respiratory function (PaO2/FiO2 ratio) and gastropulmonary microaspiration assessed by pepsin measurements in deep tracheal aspirates(DTA). Methods: 20 intubated patients on acid suppressive medication for stress ulcer prophylaxis in a neurological and medical ICU were included in this study. Patients who had pneumonia at the time of intubation or who were diagnosed with pneumonia during the first 48 hours after intubation were excluded. Pepsinmeasurements weremade onDTA samples on the third day. Afterwards esophageal impedance/pHmetry catheters were placed and 24 hour recordings were analyzed. Patients were followed throughout their stay in ICU for VAP and daily PaO2/FiO2 ratios were recorded for one week. Impedance/pH values and pepsin levels were compared between VAP and nonVAP patients. Results: 8 patients were diagnosed with VAP. VAP patients had more proximal reflux compared to non-VAP patients (7(2-14) vs. 3,5(0-8))(p=0,003). Proximal weakly acidic reflux was again more common in VAP patients (4,5(2-9) vs 2(04)(p=0,006). Pepsin levels in DTA samples were correlated with the number of weakly acidic reflux episodes(r=0,615;p=0,004). Pepsin levels were also correlated with the number of proximal reflux episodes, especially with proximal weakly acidic reflux(r=0,489;p=0,029 ; r=0,651,p=0,002 ). PaO2/FiO2 ratios were negatively correlated with both pepsin levels and proximal weakly acidic reflux (r=-0,585,p=0,007 ; r=-0,620;p=0,004). Conclusion: Proximal extension of GER, especially proximal weakly acidic reflux is associated with microaspiration, VAP and worsening of respiratory function in intubated ICU patients on acid suppressive therapy.