title: Evaluation of pH on removed tracheal tubes after general anesthesia: a prospective observational study.
abstract: OBJECTIVE
  Aspiration pneumonia is a complication of tracheal intubation and mechanical ventilation. We hypothesized that tracheal tubes removed after anesthesia that have an acidic pH may reflect latent regurgitation of gastric fluid.
  
  
  METHODS
  A prospective observational study.
  
  
  METHODS
  Operating room.
  
  
  METHODS
  Tracheal tubes removed from 200 patients (age range, 20-85 years) who had undergone general anesthesia with tracheal intubation and gastric tube placement were examined.
  
  
  METHODS
  To detect regurgitated gastric fluid on the tubes, we measured pH at 5 different points along the tubes and in the water in which the removed tracheal tubes were immersed.
  
  
  RESULTS
  Of the 200 removed tracheal tubes, 5 had an acidic pH. The tubes were used in patients who were in the prone (1 patients) or head-down (4 patients) position while under anesthesia. The incidence of acidic pH was significantly higher in patients who were in the prone (1/32) or head-down (4/56) position, compared with those in the supine (0/92) or lateral (0/20) position (P<.05).
  
  
  CONCLUSIONS
  Acidic pH was found on about 2.5% of removed tracheal tubes. These tubes were used in patients who were in the prone or head-down position during general anesthesia, although they did not exhibit significant aspiration symptom. Anesthesiologists should be aware of the inherent risk of gastric fluid regurgitation when their patients undergo general anesthesia in these positions.
authors.affiliation: Assistant Professor, Department of Anesthesiology, Osaka Medical College, Osaka, Japan.
authors.forename: Shiho
authors.initials: S
authors.lastname: Deguchi
authors.affiliation: Assistant Professor, Department of Anesthesiology, Osaka Medical College, Osaka, Japan.
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Komasawa
authors.affiliation: Assistant Professor, Department of Anesthesiology, Osaka Medical College, Osaka, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ueno
authors.affiliation: Resident, Department of Oral and Maxillofacial Reconstructive Surgery, Osaka Medical College, Osaka, Japan. Electronic address: ane078@osaka-med.ac.jp.
authors.forename: Michi
authors.initials: M
authors.lastname: Omori
authors.affiliation: Professor and Chief, Department of Anesthesiology, Osaka Medical College, Osaka, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Minami
mesh_terms: D000768:Anesthesia, General; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D011015:Pneumonia, Aspiration / Q000175:diagnosis*; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000295:instrumentation*
keywords: General anesthesia; Regurgitation; Tracheal tube; pH