Kjaergaard S, Rees S E, Nielsen J A, Freundlich M, Thorgaard P, Andreassen S
Department of Anaesthesiology, Aalborg Hospital, Denmark.
Acta Anaesthesiol Scand. 2001 Mar;45(3):349-56. doi: 10.1034/j.1399-6576.2001.045003349.x.
Late postoperative arterial hypoxaemia is common after major surgery, and may contribute to cardiovascular, cerebral or wound complications. This study investigates the time course of hypoxaemia following gynaecological laparotomy, and estimates parameters of mathematical models of pulmonary gas exchange to describe hypoxaemia.
Twelve patients were studied on four occasions; preoperatively, 2, 8 and 48 h after surgery. On each occasion inspired oxygen fraction (FIO2) was varied, changing end-expired oxygen fraction (FEO2) to achieve arterial oxygen saturations (SaO2) ranging from 90% to 100%. Measurements of ventilation and blood gases were taken. Oxygenation was characterized plotting FEO2 against SaO2. The shape and position of the FEO2/SaO2 curve was described using two mathematical models including parameters describing gas exchange: either shunt and resistance to oxygen diffusion (Rdiff); or shunt and asymmetry of ventilation-perfusion (fA2).
Two hours after surgery SaO2 was reduced from 97.5%+/-1.2% (mean+/-SD) to 93.8%+/-2.7% (mean+/-SD) (P<0.001). Values of shunt, Rdiff and fA2 were significantly changed at 2 and 8 h postoperatively. Forty-eight hours postoperatively Rdiff and fA2 were still significantly changed.
Oxygenation in 12 patients preoperatively, 2, 8 and 48 h after gynaecological laparotomy is described. Two patients were hypoxaemic (SaO2 <92%) 48 h postoperatively. When two different models of oxygen transport are fitted to patient data, high values of Rdiff or low values of fA2 describe the right shift in the FEO2/SaO2 curve seen in patients with oxygenation problems. These models fit patient data identically, and may be useful in quantifying postoperative hypoxaemia.
大手术后术后晚期动脉低氧血症很常见，可能导致心血管、脑或伤口并发症。本研究调查了妇科剖腹手术后低氧血症的时间进程，并估计肺气体交换数学模型的参数以描述低氧血症。
对12名患者在四个时间点进行研究，即术前、术后2小时、8小时和48小时。在每个时间点，改变吸入氧分数（FIO2），调整呼气末氧分数（FEO2）以实现动脉血氧饱和度（SaO2）在90%至100%之间。进行通气和血气测量。通过绘制FEO2与SaO2的关系来表征氧合情况。使用两个数学模型描述FEO2/SaO2曲线的形状和位置，这两个模型包括描述气体交换的参数：分流和氧扩散阻力（Rdiff）；或分流和通气-灌注不对称性（fA2）。
术后2小时，SaO2从97.5%±1.2%（平均值±标准差）降至93.8%±2.7%（平均值±标准差）（P<0.001）。术后2小时和8小时，分流、Rdiff和fA2值有显著变化。术后48小时，Rdiff和fA2仍有显著变化。
描述了12名患者在妇科剖腹手术前、术后2小时、8小时和48小时的氧合情况。两名患者术后48小时出现低氧血症（SaO2<92%）。当将两种不同的氧输送模型应用于患者数据时，Rdiff高值或fA2低值描述了存在氧合问题患者中FEO2/SaO2曲线的右移。这些模型对患者数据的拟合效果相同，可能有助于量化术后低氧血症。
