Department of Anesthesiology and Intensive Care, St. Anne's University Hospital, Brno, Czech Republic.
Department of Sports Medicine and Rehabilitation, St. Anne's University Hospital, Brno, Czech Republic; Faculty of Medicine, Masaryk University, Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic.
J Cardiothorac Vasc Anesth. 2019 Jul;33(7):1956-1962. doi: 10.1053/j.jvca.2019.01.057. Epub 2019 Feb 8.
One-lung ventilation (OLV) may be complicated by hypoxemia. Ventilatory efficiency, defined as the ratio of minute ventilation to carbon dioxide output (V/VCO), is increased with ventilation/perfusion mismatch and pulmonary artery hypertension, both of which may be associated with hypoxemia. Hence, the authors hypothesized increased V/VCO will predict hypoxemia during OLV.
Prospective observational study.
Single-center, university, tertiary care hospital.
The study comprised 50 consecutive lung resection candidates.
All patients underwent cardiopulmonary exercise testing before surgery. Patients who required inspired oxygen fraction (FO) ≥0.7 to maintain arterial oxygen (O) saturation >90% after 30 minutes of OLV were considered to be hypoxemic. The Student t or Mann-Whitney U test were used for comparison of patients who became hypoxemic and those who did not. Multiple regression analysis adjusted for age, sex, and body mass index was used to evaluate which parameters were associated with the V/VCO slope. Data are summarized as mean ± standard deviation.
Twenty-four patients (48%) developed hypoxemia. There was no significant difference in age, sex, and body mass index between hypoxemic and nonhypoxemic patients. However, patients with hypoxemia had a significantly higher V/VCO slope (30 ± 5 v 27 ± 4; p = 0.04) with exercise and lower partial pressure of oxygen/FO (129 ± 92 v 168 ± 88; p = 0.01), higher mean positive end-expiratory pressure (6.6 ± 1.5 v 5.6 ± 0.9 cmHO; p = 0.02), and lower mean pulse oximetry O saturation/FO index (127 ± 20 v 174 ± 17; p < 0.01) during OLV. Multiple regression showed V/VCO to be independently associated with the mean pulse oximetry O saturation/FO index (b = -0.28; F = 3.1; p = 0.05).
An increased V/VCO slope may predict hypoxemia development in patients who undergo OLV.
单肺通气（OLV）可能会导致低氧血症。通气效率定义为分钟通气量与二氧化碳输出量（V/VCO）的比值，随着通气/灌注不匹配和肺动脉高压而增加，这两者都可能与低氧血症有关。因此，作者假设增加 V/VCO 将预测 OLV 期间的低氧血症。
前瞻性观察性研究。
单中心、大学、三级护理医院。
该研究包括 50 名连续的肺切除术候选者。
所有患者在手术前均进行心肺运动测试。需要吸入氧分数（FO）≥0.7 以维持动脉氧（O）饱和度>90%的患者 30 分钟后被认为是低氧血症。使用学生 t 检验或曼-惠特尼 U 检验比较发生低氧血症和未发生低氧血症的患者。使用多元回归分析调整年龄、性别和体重指数，以评估哪些参数与 V/VCO 斜率相关。数据以平均值±标准差表示。
24 名患者（48%）出现低氧血症。低氧血症和非低氧血症患者的年龄、性别和体重指数无显著差异。然而，低氧血症患者的 V/VCO 斜率明显更高（30±5 比 27±4；p=0.04），而动脉血氧分压/FO 比值更低（129±92 比 168±88；p=0.01），平均呼气末正压（6.6±1.5 比 5.6±0.9 cmHO；p=0.02）更高，OLV 期间平均脉搏血氧饱和度/FO 指数更低（127±20 比 174±17；p<0.01）。多元回归显示 V/VCO 与平均脉搏血氧饱和度/FO 指数独立相关（b=-0.28；F=3.1；p=0.05）。
V/VCO 斜率增加可能预测接受 OLV 的患者低氧血症的发生。
