title: Accuracy of alpha amylase in diagnosing microaspiration in intubated critically-ill patients.
abstract: OBJECTIVE
  Amylase concentration in respiratory secretions was reported to be a potentially useful marker for aspiration and pneumonia. The aim of this study was to determine accuracy of α-amylase in diagnosing microaspiration in critically ill patients.
  
  
  METHODS
  Retrospective analysis of prospectively collected data collected in a medical ICU. All patients requiring mechanical ventilation for at least 48 h, and included in a previous randomized controlled trial were eligible for this study, provided that at least one tracheal aspirate was available for α-amylase measurement. As part of the initial trial, pepsin was quantitatively measured in all tracheal aspirates during a 48-h period. All tracheal aspirates were frozen, allowing subsequent measurement of α-amylase for the purpose of the current study. Microaspiration was defined as the presence of at least one positive tracheal aspirate for pepsin (>200 ng.mL-1). Abundant microaspiration was defined as the presence of pepsin at significant level in >74% of tracheal aspirates.
  
  
  RESULTS
  Amylase was measured in 1055 tracheal aspirates, collected from 109 patients. Using mean α-amylase level per patient, accuracy of α-amylase in diagnosing microaspiration was moderate (area under the receiver operator curve 0.72±0.05 [95%CI 0.61-0.83], for an α-amylase value of 1685 UI.L-1). However, when α-amylase levels, coming from all samples, were taken into account, area under the receiver operator curve was 0.56±0.05 [0.53-0.60]. Mean α-amylase level, and percentage of tracheal aspirates positive for α-amylase were significantly higher in patients with microaspiration, and in patients with abundant microaspiration compared with those with no microaspiration; and similar in patients with microaspiration compared with those with abundant microaspiration. α-amylase and pepsin were significantly correlated (r2 = 0.305, p = 0.001).
  
  
  CONCLUSIONS
  Accuracy of mean α-amylase in diagnosing microaspiration is moderate. Further, when all α-amylase levels were taken into account, α-amylase was inaccurate in diagnosing microaspiration, compared with pepsin.
authors.affiliation: Intensive Care Unit, Valenciennes Hospital, avenue Desandrouin, Valenciennes, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Dewavrin
authors.affiliation: Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, Lille II University, Lille, France.
authors.forename: Farid
authors.initials: F
authors.lastname: Zerimech
authors.affiliation: Medical Intensive Care Unit, CHU Bordeaux, Place Amélie Raba Léon, Bordeaux, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Boyer
authors.affiliation: Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, Lille II University, Lille, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Maboudou
authors.affiliation: Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, Lille II University, Lille, France.
authors.forename: Malika
authors.initials: M
authors.lastname: Balduyck
authors.affiliation: Epidemiology, Public Health and Quality of Care, Nord-de-France University, Lille, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Duhamel
authors.affiliation: Critical Care Center, R. Salengro Hospital, University Hospital of Lille, Lille, France; Medical Assessment Laboratory, EA 2694, University of Lille Nord de France, Lille, France.
authors.forename: Saad
authors.initials: S
authors.lastname: Nseir
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008297:Male; D008875:Middle Aged; D010434:Pepsin A / Q000378:metabolism; D012372:ROC Curve; D012121:Respiration, Artificial; D053120:Respiratory Aspiration / Q000175:diagnosis* / Q000201:enzymology; D012131:Respiratory Insufficiency / Q000628:therapy; D012189:Retrospective Studies; D014132:Trachea / Q000201:enzymology; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D000516:alpha-Amylases; D010434:Pepsin A