Diagnosis and Management of Obesity Hypoventilation Syndrome during Labor

Obesity hypoventilation syndrome (OHS) is a disorder in which patients with a body mass index ≥30 kg/m2 develop awake hypercapnia with a partial pressure of carbon dioxide ≥45 mm Hg, in the absence of other diseases that may produce alveolar hypoventilation. Additional clinical features include slee...

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Bibliographic Details
Main Authors: Brandon M. Togioka, Sarah S. McConville, Rachael M Penchoen-Lind, Katie J. Schenning
Format: Article
Language:English
Published: Wiley 2021-01-01
Series:Case Reports in Anesthesiology
Online Access:http://dx.doi.org/10.1155/2021/8096212
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Summary:Obesity hypoventilation syndrome (OHS) is a disorder in which patients with a body mass index ≥30 kg/m2 develop awake hypercapnia with a partial pressure of carbon dioxide ≥45 mm Hg, in the absence of other diseases that may produce alveolar hypoventilation. Additional clinical features include sleep disordered breathing, restrictive lung disease, polycythemia, hypoxemia, and an increased serum bicarbonate concentration (≥27 mEq/L). Anesthesia providers should be familiar with OHS because it is often undiagnosed, it is associated with a higher mortality rate than obstructive sleep apnea, and it is projected to increase in prevalence along with the obesity epidemic. In this case, a 33-year-old obese woman with presumed OHS developed respiratory acidosis during induction of labor. Continuous positive airway pressure treatment was initiated, but the patient continued to have hypercapnia. A cesarean delivery was recommended. The patient had baseline orthopnea due to her body habitus; thus, despite adequate labor analgesia, a cesarean delivery was completed with general endotracheal anesthesia. We believe this patient had OHS despite a serum bicarbonate <27 mEq/L, a partial pressure of oxygen >70 mm Hg, and a hemoglobin <16 g/dL, which would typically rule out OHS. Pregnant women experience a decrease in serum bicarbonate concentration due to progesterone-mediated hyperventilation, an increase in arterial oxygenation from increased minute ventilation and higher cardiac output, and a decrease in hemoglobin due to the physiologic anemia of pregnancy. Thus, OHS may be defined differently in pregnant than in non-pregnant patients.
ISSN:2090-6382
2090-6390