Ida Keila K, Fantoni Denise T, Souto Maria T M R, Otsuki Denise A, Zoppa André L V, Silva Luis C L C, Ambrósio Aline M
Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil.
Vet Anaesth Analg. 2013 Jul;40(4):339-50. doi: 10.1111/vaa.12041. Epub 2013 Apr 20.
To determine if pressure support ventilation (PSV) weaning from general anesthesia affects ventilation or oxygenation in horses.
Prospective randomized clinical study.
Twenty client-owned healthy horses aged 5 ± 2 years, weighing 456 ± 90 kg.
In the control group (CG; n = 10) weaning was performed by a gradual decrease in respiratory rate (fR ) and in the PSV group (PSVG; n = 10) by a gradual decrease in fR with PSV. The effect of weaning was considered suboptimal if PaCO2 > 50 mmHg, arterial pH < 7.35 plus PaCO2 > 50 mmHg or PaO2 < 60 mmHg were observed at any time after disconnection from the ventilator until 30 minutes after the horse stood. Threshold values for each index were established and the predictive power of these values was tested.
Pressure support ventilation group (PSVG) had (mean ± SD) pH 7.36 ± 0.02 and PaCO2 41 ± 3 mmHg at weaning and the average lowest PaO2 69 ± 6 mmHg was observed 15 minutes post weaning. The CG had pH 7.32 ± 0.02 and PaCO2 57 ± 6 mmHg at weaning and the average lowest PaO2 48 ± 5 mmHg at 15 minutes post weaning. No accuracy in predicting weaning effect was observed for fR (p = 0.3474), minute volume (p = 0.1153), SaO2 (p = 0.1737) and PaO2 /PAO2 (p = 0.1529). A high accuracy in predicting an optimal effect of weaning was observed for VT > 10 L (p = 0.0001), fR /VT ratio ≤ 0.60 breaths minute(-1) L(-1) (p = 0.0001), VT /bodyweight > 18.5 mL kg(-1) (p = 0.0001) and PaO2 /FiO2 > 298 (p = 0.0002) at weaning. A high accuracy in predicting a suboptimal effect of weaning was observed for VT < 10 L (p = 0.0001), fR /VT ratio ≥ 0.60 breaths minute(-1) L(-1) (p = 0.0001) and Pe'CO2 ≥ 38 mmHg (p = 0.0001) at weaning.
Pressure support ventilation (PSV) weaning had a better respiratory outcome. A higher VT , VT /body weight, PaO2 /FiO2 ratio and a lower fR /VT ratio and Pe'CO2 were accurate in predicting the effect of weaning in healthy horses recovering from general anesthesia.
确定全身麻醉后压力支持通气（PSV）撤机是否会影响马的通气或氧合。
前瞻性随机临床研究。
20匹客户拥有的健康马，年龄5±2岁，体重456±90千克。
对照组（CG；n = 10）通过逐渐降低呼吸频率（fR）进行撤机，PSV组（PSVG；n = 10）通过逐渐降低fR并结合PSV进行撤机。如果在从呼吸机断开连接后直至马站立后30分钟内的任何时间观察到PaCO2> 50 mmHg、动脉pH < 7.35加PaCO2> 50 mmHg或PaO2 < 60 mmHg，则认为撤机效果欠佳。确定每个指标的阈值并测试这些值的预测能力。
PSV组（PSVG）撤机时（均值±标准差）pH为7.36±0.02，PaCO2为41±3 mmHg，撤机后15分钟观察到的最低平均PaO2为69±6 mmHg。对照组撤机时pH为7.32±0.02，PaCO2为57±6 mmHg，撤机后15分钟最低平均PaO2为48±5 mmHg。未观察到fR（p = 0.3474）、分钟通气量（p = 0.1153）、SaO2（p = 0.1737）和PaO2 /PAO2（p = 0.1529）对撤机效果的预测准确性。撤机时VT> 10 L（p = 0.0001）、fR /VT比值≤0.60次呼吸·分钟-1·L-1（p = 0.0001）、VT /体重> 18.5 mL·kg-1（p = 0.0001）和PaO2 /FiO2> 298（p = 0.0002）对预测撤机的最佳效果具有较高的准确性。撤机时VT < 10 L（p = 0.0001）、fR /VT比值≥0.60次呼吸·分钟-1·L-1（p = 0.0001）和Pe'CO2≥38 mmHg（p = 0.0001）对预测撤机的欠佳效果具有较高的准确性。
压力支持通气（PSV）撤机具有更好的呼吸结局。较高的VT、VT /体重、PaO2 /FiO2比值以及较低的fR /VT比值和Pe'CO2可准确预测从全身麻醉中恢复的健康马的撤机效果。
