Togioka Brandon M, McConville Sarah S, Penchoen-Lind Rachael M, Schenning Katie J
Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR, USA.
Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR, USA.
Case Rep Anesthesiol. 2021 Aug 25;2021:8096212. doi: 10.1155/2021/8096212. eCollection 2021.
Obesity hypoventilation syndrome (OHS) is a disorder in which patients with a body mass index ≥30 kg/m 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.
肥胖低通气综合征（OHS）是一种疾病，即体重指数≥30kg/m²的患者在清醒状态下出现二氧化碳分压≥45mmHg的高碳酸血症，且不存在其他可能导致肺泡通气不足的疾病。其他临床特征包括睡眠呼吸障碍、限制性肺病、红细胞增多症、低氧血症以及血清碳酸氢盐浓度升高（≥27mEq/L）。麻醉医生应熟悉OHS，因为它常常未被诊断出来，其死亡率高于阻塞性睡眠呼吸暂停，而且预计随着肥胖症的流行其患病率还会增加。在本病例中，一名疑似患有OHS的33岁肥胖女性在引产过程中发生了呼吸性酸中毒。开始进行持续气道正压通气治疗，但患者仍持续存在高碳酸血症。建议进行剖宫产。该患者因体型原因基线存在端坐呼吸；因此，尽管分娩镇痛充分，仍在全身气管内麻醉下完成了剖宫产。我们认为，尽管该患者血清碳酸氢盐<27mEq/L、氧分压>70mmHg且血红蛋白<16g/dL，这些通常可排除OHS，但她仍患有OHS。孕妇由于孕酮介导的通气过度会出现血清碳酸氢盐浓度降低，由于分钟通气量增加和心输出量升高会出现动脉氧合增加，以及由于妊娠生理性贫血会出现血红蛋白降低。因此，OHS在孕妇中的定义可能与非孕妇不同。
