Pankow W, Hijjeh N, Schüttler F, Penzel T, Becker H F, Peter J H, von Wichert P
Dept of Internal Medicine, Schlafmedizinisches Labor, Medizinische Poliklinik, Philipps-University, Marburg, Germany.
Eur Respir J. 1997 Dec;10(12):2847-52. doi: 10.1183/09031936.97.10122847.
Noninvasive positive pressure ventilation (NPPV) can improve ventilation in obese subjects during the postoperative period after abdominal surgery. Compared to nasal continuous positive airway pressure (nCPAP), NPPV was superior in correcting blood gas abnormalities both during the night-time and during the daytime in a subgroup of patients with the obesity hypoventilation syndrome (OHS). However, as it is unknown, if and to what extent NPPV can unload the respiratory muscles in the face of the increased impedance of the respiratory system in obesity, this is what was investigated. Eighteen obese subjects with a body mass index > or = 40 kg x m(-2) were investigated during the daytime, which included five healthy controls (simple obesity (SO)), seven patients with obstructive sleep apnoea (OSA) and six patients with the obesity hypoventilation syndrome (OHS). Assisted PPV was performed with bi-level positive airway pressure (BiPAP), applied via a face mask. Inspiratory positive airway pressure (IPAP) was set to 1.2 or 1.6 kPa and expiratory positive airway pressure (EPAP) was set to 0.5 kPa. Inspiratory muscle activity was measured as diaphragmatic pressure time product (PTPdi). Comparison of spontaneous breathing with BiPAP ventilation showed no significant difference in breathing pattern, although there was a tendency towards an increase in tidal volume (VT) in all three groups and a decrease in respiratory frequency (fR) in patients with OSA and OHS. End-tidal carbon dioxide (PET,CO2) with BiPAP was unchanged in SO and OSA, but was decreased in OHS. In contrast, inspiratory muscle activity was reduced by at least 40% in each group. This was indicated by a decrease in PTPdi with BiPAP 1.2/0.5 kPa from mean+/-SD 39+/-5 to 20+/-9 kPa x s (p<0.05) in SO, from 42+/-7 to 21+/-8 kPa x s (p<0.05) in OSA, and from 64+/-20 to 38+/-17 kPa x s (p<0.05) in OHS. With BiPAP 1.6/0.5 kPa, PTPdi was further reduced to 17+/-6 kPa x s in SO, and to 17+/-6 kPa x s in OSA, but not in OHS (40+/-22 kPa x s). We conclude that noninvasive assisted ventilation unloads the inspiratory muscles in patients with gross obesity.
无创正压通气（NPPV）可改善肥胖患者腹部手术后的通气状况。与经鼻持续气道正压通气（nCPAP）相比，在肥胖低通气综合征（OHS）患者亚组中，NPPV在纠正夜间和白天的血气异常方面更具优势。然而，由于尚不清楚NPPV在肥胖患者呼吸系统阻抗增加的情况下能否以及在多大程度上减轻呼吸肌负荷，因此对此进行了研究。对18名体重指数≥40 kg·m⁻²的肥胖受试者进行了白天的研究，其中包括5名健康对照者（单纯肥胖（SO））、7名阻塞性睡眠呼吸暂停（OSA）患者和6名肥胖低通气综合征（OHS）患者。通过面罩应用双水平气道正压通气（BiPAP）进行辅助正压通气。吸气气道正压（IPAP）设定为1.2或1.6 kPa，呼气气道正压（EPAP）设定为0.5 kPa。吸气肌活动以膈肌压力时间乘积（PTPdi）来衡量。自发呼吸与BiPAP通气的比较显示，呼吸模式无显著差异，尽管三组的潮气量（VT）均有增加趋势，OSA和OHS患者的呼吸频率（fR）有所下降。SO组和OSA组使用BiPAP时的呼气末二氧化碳（PET,CO2）不变，但OHS组有所降低。相反，每组的吸气肌活动至少降低了40%。这表现为SO组使用BiPAP 1.2/0.5 kPa时，PTPdi从平均±标准差39±5降至20±9 kPa·s（p<0.05）；OSA组从42±7降至21±8 kPa·s（p<0.05）；OHS组从64±20降至38±17 kPa·s（p<0.05）。使用BiPAP 1.6/0.5 kPa时，SO组和OSA组的PTPdi进一步降至17±6 kPa·s，但OHS组未降至（40±22 kPa·s）。我们得出结论，无创辅助通气可减轻严重肥胖患者的吸气肌负荷。
