Mild to moderate hypoxemia is a relatively common occurrence during anesthesia for infants (Image source: Thinkstock)
Mild to moderate hypoxemia is a relatively common occurrence during anesthesia for infants (Image source: Thinkstock)

Children undergoing anesthesia are known to have a greater likelihood of developing intraoperative hypoxemia in part due to reduced functional residual capacity and higher metabolic requirements compared to adults.  How often do children become hypoxemic during anesthesia?  Jurgen C. de Graaff, Department of Pediatric Anesthesia, Wilhelmina Children’s Hospital, Division of Anesthesiology, Intensive Care and Emergency Medicine University Medical Center Utrecht, Utrecht, The Netherlands, and colleagues prospectively examined the incidence of hypoxemia, defined as SpO2 < 90 for at least 1 min and not due to artifact, and pulse oximeter artifact of 575 children undergoing non-cardiac surgery over a two month period in 2005 using their anesthesia information management system.   Artifact determination was based on contact with the anesthesiologist. Their findings are published in the July issue of Anesthesia & Analgesia in the article titled “Incidence of Intraoperative Hypoxemia in Children in Relation to Age.”

At least one episode of true hypoxemia, i.e., no artifact, was seen in 35 of 575 cases.  The incidence of hypoxemia was 20 episodes per 100 cases and 0.16 incidents per hour of anesthesia.  Notably, hypoxemia incidence was greater for younger patients; the incidence was as high as 142 incidents per 100 cases (0.5 incidents per hour) for neonates compared to 13 incidents per 100 cases (0.08 incidents per hour) for adolescents.  Of 67 true hypoxemic episodes, in 6% the duration was greater than 5 min and in 14 episodes the SpO2 was ≤ 80%.  Of the 67 episodes, 19 occurred during induction, 31 were during anesthesia maintenance, and 17 occurred during emergence.  Eight hypoxemic events were accompanied by bradycardia, and atropine was administered for 3 patients.  Overall, hypoxemic episodes at least 1 min in duration would occur in 17 of 100 cases and by age would range between 11 per 100 children aged 8-16 years versus 92 episodes per 100 neonates.

Mild to moderate hypoxemia, then, is relatively common.  Unfortunately the authors did not measure the clinical consequences of these hypoxemic episodes after surgery.   The authors showed that given that 65% of hypoxemic events were true hypoxemic events, retrospective reviews of hypoxemia would be flawed.  In addition, this review highlighted the performance of anesthesiologists at a children’s hospital:  would there be a difference in the number of episodes of true hypoxemia if such children were cared for by anesthesiologists with not as much experience in caring for such patients?

To read more about anesthesia and neonates, see the summary in  OpenAnesthesia.