Postoperative Hypoxemia Is Common and Persistent: A Prospective Blinded Observational Study.
BACKGROUND
The incidence, severity, and duration of postoperative oxygen desaturation in the general surgical population are poorly characterized. We therefore used continuous pulse oximetry to quantify arterial oxygen saturation (SpO2) in a cross-section of patients having noncardiac surgery.


METHODS
Oxygen saturation, blinded to clinicians, was recorded at 1-minute intervals in patients >45 years old for up to 48 hours after noncardiac surgery in 1250 patients from Cleveland Clinic Main Campus and 250 patients from the Juravinski Hospital. We determined (1) the cumulative minutes of raw minute-by-minute values below various hypoxemic thresholds; and (2) the contiguous duration of kernel-smoothed (sliding window) values below various hypoxemic thresholds. Finally, we compared our blinded continuous values with saturations recorded during routine nursing care.


RESULTS
Eight hundred thirty-three patients had sufficient data for analyses. Twenty-one percent had ≥10 min/h with raw SpO2 values <90% averaged over the entire recording duration; 8% averaged ≥20 min/h <90%; and 8% averaged ≥5 min/h <85%. Prolonged hypoxemic episodes were common, with 37% of patients having at least 1 (smoothed) SpO2 <90% for an hour or more; 11% experienced at least 1 episode lasting ≥6 hours; and 3% had saturations <80% for at least 30 minutes. Clinical hypoxemia, according to nursing records, measured only in Cleveland Clinic patients (n = 594), occurred in 5% of the monitored patients. The nurses missed 90% of smoothed hypoxemic episodes in which saturation was <90% for at least one hour.


CONCLUSIONS
Hypoxemia was common and prolonged in hospitalized patients recovering from noncardiac surgery. The SpO2 values recorded in medical records seriously underestimated the severity of postoperative hypoxemia.
From the Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio; Department of Medicine, The Population Health Research Institute, David Braley Cardiac, Vascular, and Stroke Research Institute, Hamilton, Ontario, Canada; Department of Medicine, Juravinski Hospital of the Hamilton Health Sciences, Hamilton, Ontario, Canada; and Adult Cardiology and Department of Internal Medicine, McMaster University, Hamilton, Ontario, Canada.
Zhuo
Z
Sun
Daniel I
DI
Sessler
Jarrod E
JE
Dalton
P J
PJ
Devereaux
Aram
A
Shahinyan
Amanda J
AJ
Naylor
Matthew T
MT
Hutcherson
Patrick S
PS
Finnegan
Vikas
V
Tandon
Saeed
S
Darvish-Kazem
Shaan
S
Chugh
Hussain
H
Alzayer
Andrea
A
Kurz
D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010092:Oximetry / Q000379:methods / Q000639:trends*; D011183:Postoperative Complications / Q000097:blood / Q000175:diagnosis*; D011446:Prospective Studies; D016037:Single-Blind Method