Mo1184 Acid and Nonacid Gastroesophageal Reflux and Pepsin Isoforms (A and C) in Tracheal Secretion of Critically Ill Children

Abstract

Background and Aims: Gastroesophageal reflux (GER) and pulmonary aspiration (PA) are frequent in intensive care unit (ICU) patients. The presence of pepsin in airways seems to be the link between them. However, pepsin isoforms A (gastric specific) and C (pneumocyte potentially derived) needs to be distinguished. This study aimed to evaluate GER patterns and to determine the presence of pepsin A and C in tracheal secretion of critically ill mechanically ventilated children. Patients and Methods: Thirty-four critically ill children undergoing mechanical ventilation were enrolled. All were sedated, on full enteral nutrition and underwent multichannel intraluminal impedance-pH monitoring (MII-pH) by using equipment Sleuth-Sandhill Scientific, USA. Data were manually analyzed by using software BioVIEW Analysis version 5.6 (Sandhill Scientific). MII-pH parameters analyzed were: number of total episodes of GER (NGER); height of refluxate (proximal or distal); reflux content (acid, when ph 4); and acid reflux index [(ARI) percentage of time when pH 10% in children under 1 year age and >5% in older than 1 year). Tracheal secretion samples were collected from each patient to determine the presence of pepsin. Pepsin A and C were evaluated by Western-Blot. The following variables were also considered for analysis: use of antiacid medicines (yes or no) and placement of enteral feeding tube (gastric or post-pyloric). Wilcoxon test was used to compare acid vs nonacid GER. Mann-Whitney test was used to compare the number of reflux episodes of patients on and off antiacid medicines or patients with gastric or postpyloric feeding. Results: Median (range) age was 4(1-174) months and 23 were males. Nineteen (55.9%) were on antiacid secretory medicines (9 ranitidine, 10 omeprazol). MIIpH detected 2172 GER episodes, 77.0% were nonacid and 71.7% were proximal. Median (25th-75thpercentile) of NGER episodes/patient was 59.5 (20.3-85.3). Nonacid GER episodes/ patient were significantly more frequently than acid GER episodes/patient [median (25th75th percentile) 43.5 (20.3 68.3) vs 1.0 (0 13.8), respectively], p<0.001. Only 3 patients had acid reflux index altered (44.9%, 12.7%, and 13.6%), all off antiacid drugs. The results remained significant after controlling the use of antiacids and placement of enteral tube feeding to all parameters. Pepsin A was found in 100% of samples, pepsin C in 76.5%. Conclusion: The majority of GER episodes of ICU children were proximal and nonacid. All patients had aspiration of gastric contents detected by pepsin A in tracheal fluid. A specific pepsin assay should be performed to establish gastropulmonary aspiration since pepsin C was found in more than 70% of samples.