title: Acid and Weakly Acidic Gastroesophageal Reflux and Pepsin Isoforms (A and C) in Tracheal Secretions of Critically Ill Children.
abstract: BACKGROUND
  Gastroesophageal reflux (GER) and pulmonary aspiration are frequent in patients in the ICU. The presence of pepsin in airways seems to be the link between them. However, pepsin isoforms A (gastric specific) and C (pneumocyte potentially derived) need to be distinguished. This study aimed to evaluate GER patterns and to determine the presence of pepsin A and C in tracheal secretions of critically ill children receiving mechanical ventilation.
  
  
  METHODS
  All patients underwent combined multichannel intraluminal impedance-pH (MII-pH) monitoring. Tracheal secretion samples were collected to determine the presence of pepsin. Pepsin A and C were evaluated by Western blot. MII-pH parameters analyzed were number of total GER episodes (NGER); acid, weakly acidic, and weakly alkaline GER episodes; and proximal and distal GER episodes.
  
  
  RESULTS
  Thirty-four patients (median age, 4 months; range, 1-174 months) were included. MII-pH monitoring detected 2,172 GER episodes (77.0% were weakly acidic; 71.7% were proximal). The median NGER episodes per patient was 59.5 (25th-75th percentile, 20.3-85.3). Weakly acidic GER episodes per patient were significantly more frequent than acid GER episodes per patient (median [25th-75th percentile], 43.5 [20.3-68.3] vs 1.0 [0-13.8], respectively; P < .001). Only three patients had an altered acid reflux index (44.9%, 12.7%, and 13.6%) while not taking antacid drugs. Pepsin A was found in 100% of samples and pepsin C in 76.5%.
  
  
  CONCLUSIONS
  The majority of GER episodes of children in the ICU were proximal and weakly acidic. All patients had aspiration of gastric contents as detected by pepsin A in tracheal fluid. A specific pepsin assay should be performed to establish gastropulmonary aspiration because pepsin C was found in > 70% of samples.
authors: Post-Graduate Program Sciences in Gastroenterology and Hepatology, Porto Alegre-RS, Brazil; Pediatric Gastroenterology Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil. Electronic address: cris.hallal@yahoo.com.
authors: Cristiane
authors: C
authors: Hallal
authors: Pediatric Intensive Care Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil.
authors: Veridiana S
authors: VS
authors: Chaves
authors: Pediatric Gastroenterology Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil.
authors: Gilberto C
authors: GC
authors: Borges
authors: Laboratory of Translational Pediatrics, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil.
authors: Isabel C
authors: IC
authors: Werlang
authors: Laboratory of Translational Pediatrics, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil.
authors: Fernanda U
authors: FU
authors: Fontella
authors: Post-Graduate Program in Child and Adolescent Health, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil.
authors: Ursula
authors: U
authors: Matte
authors: Laboratory of Translational Pediatrics, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil; Post-Graduate Program in Child and Adolescent Health, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil.
authors: Marcelo Z
authors: MZ
authors: Goldani
authors: Pediatric Intensive Care Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil; Post-Graduate Program in Child and Adolescent Health, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil.
authors: Paulo R
authors: PR
authors: Carvalho
authors: Pediatric Intensive Care Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil.
authors: Eliana A
authors: EA
authors: Trotta
authors: Pediatric Intensive Care Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil.
authors: Jefferson P
authors: JP
authors: Piva
authors: Post-Graduate Program Sciences in Gastroenterology and Hepatology, Porto Alegre-RS, Brazil.
authors: Sergio G S
authors: SGS
authors: Barros
authors: Post-Graduate Program Sciences in Gastroenterology and Hepatology, Porto Alegre-RS, Brazil; Pediatric Gastroenterology Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil; Laboratory of Translational Pediatrics, Hospital de Clínicas de Porto Alegre, Porto Alegre-RS, Brazil; Post-Graduate Program in Child and Adolescent Health, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil.
authors: Helena A S
authors: HAS
authors: Goldani
mesh_terms: D000293:Adolescent; D012634:Bodily Secretions / Q000737:chemistry*; D002648:Child; D002675:Child, Preschool; D016638:Critical Illness; D004750:Enteral Nutrition; D005260:Female; D005764:Gastroesophageal Reflux; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D007231:Infant, Newborn; D015278:Intensive Care Units, Pediatric; D008297:Male; D010434:Pepsin A / Q000032:analysis*; D011446:Prospective Studies; D012121:Respiration, Artificial; D014132:Trachea
chemical_list: D010434:Pepsin A; C020557:gastricsin