Fleming Eamon, Voscopoulos Christopher, George Edward
Respiratory Motion, 411 Waverley Oaks Rd #150, Waltham, MA, 02452, USA.
Brigham and Women's Hospital, 75 Francis St, Boston, MA, 02115, USA.
J Med Case Rep. 2015 Apr 29;9:94. doi: 10.1186/s13256-015-0577-9.
Obstructive sleep apnea and opioid-induced respiratory depression can unpredictably threaten respiratory competence in the post-anesthesia care unit. Current respiratory monitoring relies heavily on respiratory rate and oxygen saturation, as well as subjective clinical assessment. These assessments have distinct limitations, and none provide a real-time, objective, quantitative direct measurement of respiratory status. A novel, non-invasive respiratory volume monitor uses bioimpedance to provide accurate, quantitative measurements of minute ventilation, tidal volume and respiratory rate continuously in real time, providing a direct measurement of ventilation.
The case describes an orthopedic surgery patient (54-year-old Caucasian man, body mass index 33.7 kg/m(2)) with diagnosed obstructive sleep apnea in whom the respiratory volume monitor data depicted persistent apneic behavior undetected by other monitoring. The monitor was able to detect a sudden reduction in minute ventilation after initial opioid administration in the post-anesthesia care unit. The patient had sustained low minute ventilation until discharge. Neither respiratory rate data from the hospital monitor nor oxygen saturation readings reflected the respiratory decompensation, remaining within normal limits even during sustained low minute ventilation.
The events of this case illustrate the limitations of current respiratory rate monitoring and pulse oximetry in the evaluation of post-surgical respiratory status. Our patient displayed stable respiratory rate and no evidence of desaturation, despite sustained low minute ventilation, and he received opioids in the post-anesthesia care unit despite already compromised ventilation. Because the available monitoring did not indicate the patient's true respiratory status, he was treated with additional opioids, markedly increasing his risk for further respiratory decline.
阻塞性睡眠呼吸暂停和阿片类药物引起的呼吸抑制可能会在麻醉后护理单元中不可预测地威胁呼吸功能。目前的呼吸监测严重依赖呼吸频率、血氧饱和度以及主观临床评估。这些评估有明显的局限性，而且没有一种能实时、客观、定量地直接测量呼吸状态。一种新型的非侵入性呼吸容积监测仪利用生物阻抗实时连续地提供准确、定量的分钟通气量、潮气量和呼吸频率测量值，从而直接测量通气情况。
该病例描述了一名骨科手术患者（54岁白种男性，体重指数33.7kg/m²），被诊断患有阻塞性睡眠呼吸暂停，呼吸容积监测仪数据显示其存在持续的呼吸暂停行为，而其他监测未检测到。该监测仪能够检测到麻醉后护理单元中首次给予阿片类药物后分钟通气量的突然下降。该患者直到出院时分钟通气量一直较低。医院监测仪的呼吸频率数据和血氧饱和度读数均未反映出呼吸代偿失调，即使在持续低分钟通气量期间仍保持在正常范围内。
该病例的情况说明了当前呼吸频率监测和脉搏血氧饱和度测定在评估术后呼吸状态方面的局限性。尽管患者分钟通气量持续较低，但我们的患者呼吸频率稳定且无血氧饱和度下降的迹象，并且在麻醉后护理单元中尽管其通气功能已经受损仍接受了阿片类药物治疗。由于现有的监测未表明患者的真实呼吸状态，他接受了额外的阿片类药物治疗，显著增加了其呼吸功能进一步下降的风险。
