TITLE:
Postoperative Apnea Induced by Fentanyl and Other Multiple Respiratory-Modulating Factors
AUTHORS:
Chie Matsuda, Jiro Sato
KEYWORDS:
Postoperative Apnea, Opioids, Pain, Chemical and Cortical Controls of Breathing
JOURNAL NAME:
Open Journal of Anesthesiology,
Vol.4 No.8,
August
8,
2014
ABSTRACT: Purpose: Opioids
are concerned as a major cause of postoperative respiratory depression. In the
immediate postoperative period, however, other factors can produce instability
of breathing such as pain, agitation, and residual effects of anesthetics. Such
factors might be overlooked masked by the fear for opioid-induced respiratory
depression. We report a case who presented apnea immediately after emergence
from anesthesia that we considered was produced by an interaction among such
factors accompanied with fentanyl-induced respiratory depression. Clinical Features:
A 31-year-old woman underwent ovarian cystectomy under general anesthesia with
continuous infusions of propofol and remifentanil, and bolus doses of fentanyl.
Transversus abdominis plane blocks with ropivacaine were given upon completion
of surgery. She complained of severe wound pain and was agitated at the
emergence from anesthesia. Fentanyl 50 μg was administered intravenously. In
several minutes, she developed apnea, unconsciousness, and difficulty of
mechanical ventilation via a face mask. The estimated effect site concentration
at the onset of the episode (2.9 ng·ml-1)
was approximately the same (3.0 ng·ml-1)
as after 30 min when she regained consciousness and spontaneous breathing. It
indicated that not only direct inhibition of the respiratory center by fentanyl
but also other stimulatory and inhibitory factors contributed to respiratory arrest.
Conclusion: In the immediate postoperative period, transient factors, such as
pain, mental instability and anesthetic residues, which are indirectly-related
with breathing, can interact each other and
with opioids. The interaction would induce apnea through mechanisms combined among direct inhibition of the respiratory center, and modulation of chemical and
cortical controls of breathing.