Pulmonary function after emergence on 100% oxygen in patients with chronic obstructive pulmonary disease: a randomized, controlled trial.
BACKGROUND
During emergence from anesthesia, breathing 100% oxygen is frequently used to provide a safety margin toward hypoxemia in case an airway problem occurs. Oxygen breathing has been shown to cause pulmonary gas exchange disorders in healthy individuals. This study investigates how oxygen breathing during emergence affects lung function specifically whether oxygen breathing causes added hypoxemia in patients with chronic obstructive pulmonary disease.


METHODS
This trial has been conducted in a parallel-arm, case-controlled, open-label manner. Fifty-three patients with chronic obstructive pulmonary disease were randomly allocated (computer-generated lists) to breathe either 100 or 30% oxygen balanced with nitrogen during emergence from anesthesia. Arterial blood gas measurements were taken before induction and at 5, 15, and 60 min after extubation.


RESULTS
All participants tolerated the study well. Patients treated with 100% oxygen had a higher alveolar-arterial oxygen pressure gradient (primary outcome) compared with patients treated with 30% oxygen (25 vs. 20 mmHg) and compared with their baseline at the 60-min measurement (25 vs. 17 mmHg). At the 60-min measurement, arterial partial pressure of oxygen was lower in the 100% group (62 vs. 67 mmHg). Arterial partial pressure of carbon dioxide and pH were not different between groups or measurements.


CONCLUSIONS
In this experiment, the authors examined oxygen breathing during emergence-a widely practiced maneuver known to generate pulmonary blood flow heterogeneity. In the observed cohort of patients already presenting with pulmonary blood flow disturbances, emergence on oxygen resulted in deterioration of oxygen-related blood gas parameters. In the perioperative care of patients with chronic obstructive pulmonary disease, oxygen breathing during emergence from anesthesia may need reconsideration.
From the Department of Anesthesiology, Innsbruck Medical University, Innsbruck, Austria (A.T.K., I.P., S.T., B.T.); Department of Anesthesiology and CCM II, Klinikum Wels, Wels, Austria (H.K.); and Department of Anesthesiology and CCM, Hanusch Hospital, Vienna, Austria (A.L.).
Axel T
AT
Kleinsasser
Iris
I
Pircher
Suzan
S
Truebsbach
Hans
H
Knotzer
Alexander
A
Loeckinger
Benedict
B
Treml
D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General / Q000379:methods; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage*; D011175:Positive-Pressure Respiration / Q000379:methods; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012129:Respiratory Function Tests / Q000379:methods
D010100:Oxygen