Day T K, Gaynor J S, Muir W W, Bednarski R M, Mason D E
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, Columbus, USA.
Vet Surg. 1995 May-Jun;24(3):266-76. doi: 10.1111/j.1532-950x.1995.tb01330.x.
One hundred sixty horses were anesthetized with xylazine, guaifenesin, thiamylal, and halothane for elective soft tissue and orthopedic procedures. Horses were randomly assigned to one of four groups. Group 1 (n = 40): Horses positioned in lateral (LRG1; n = 20) or dorsal (DRG1; n = 20) recumbency breathed spontaneously throughout anesthesia. Group 2 (n = 40): Intermittent positive pressure ventilation (IPPV) was instituted throughout anesthesia in horses positioned in lateral (LRG2; n = 20) or dorsal (DRG2; n = 20) recumbency. Group 3 (n = 40): Horses positioned in lateral (LRG3; n = 20) or dorsal (DRG3; n = 20) recumbency breathed spontaneously for the first half of anesthesia and intermittent positive pressure ventilation was instituted for the second half of anesthesia. Group 4 (n = 40): Intermittent positive pressure ventilation was instituted for the first half of anesthesia in horses positioned in lateral (LRG4; n = 20) or dorsal (DRG4; n = 20) recumbency. Spontaneous ventilation (SV) occured for the second half of anesthesia. The mean time of anesthesia was not significantly different within or between groups. The mean time of SV and IPPV was not significantly different in groups 3 and 4. Variables analyzed included pH, PaCO2, PaO2, and P(A-a)O2 (calculated). Spontaneous ventilation resulted in significantly higher PaCO2 and P(A-a)O2 values and significantly lower PaO2 values in LRG1 and DRG1 horses compared with LRG2 and DRG2 horses. Intermittent positive pressure ventilation resulted in normocarbia and significantly lower P(A-a)O2 values in LRG2 and DRG2 horses. In LRG2 the PaO2 values significantly increased from 20 minutes after induction to the end of anesthesia. The PaO2 and P(A-a)O2 values were not significantly different from the beginning of anesthesia after IPPV in DRG2 or DRG3. The PaO2 values significantly decreased and the P(A-a)O2 values significantly increased after return to SV in horses in LRG4 and DRG4. The PaO2 values were lowest and the P(A-a)O2 values were highest in all horses positioned in dorsal recumbency compared with lateral recumbency and in SV horses compared with IPPV horses. The pH changes paralleled the changes in PaCO2. Blood gas values during right versus left lateral recumbency in all groups were also evaluated. The PaO2 values were significantly lower and the P(A-a)O2 values were significantly higher during SV in horses positioned in left lateral (LRLG1) compared with right lateral (LRRG1) recumbency.(ABSTRACT TRUNCATED AT 400 WORDS)
160匹马使用赛拉嗪、愈创甘油醚、硫喷妥钠和氟烷进行麻醉，以进行择期软组织和骨科手术。马匹被随机分为四组。第1组（n = 40）：侧卧（LRG1；n = 20）或仰卧（DRG1；n = 20）的马匹在整个麻醉过程中自主呼吸。第2组（n = 40）：侧卧（LRG2；n = 20）或仰卧（DRG2；n = 20）的马匹在整个麻醉过程中进行间歇正压通气（IPPV）。第3组（n = 40）：侧卧（LRG3；n = 20）或仰卧（DRG3；n = 20）的马匹在麻醉的前半程自主呼吸，后半程进行间歇正压通气。第4组（n = 40）：侧卧（LRG4；n = 20）或仰卧（DRG4；n = 20）的马匹在麻醉的前半程进行间歇正压通气，后半程自主呼吸。各组内或组间的平均麻醉时间无显著差异。第3组和第4组的自主通气（SV）和IPPV平均时间无显著差异。分析的变量包括pH、动脉血二氧化碳分压（PaCO2）、动脉血氧分压（PaO2）和肺泡-动脉血氧分压差（P(A-a)O2，计算值）。与LRG2和DRG2组的马匹相比，LRG1和DRG1组的马匹自主呼吸导致PaCO2和P(A-a)O2值显著升高，PaO2值显著降低。间歇正压通气使LRG2和DRG2组的马匹出现正常碳酸血症，P(A-a)O2值显著降低。在LRG2组，PaO2值从诱导后20分钟到麻醉结束时显著升高。DRG2或DRG3组在IPPV后从麻醉开始时起，PaO2和P(A-a)O2值无显著差异。LRG4和DRG4组的马匹恢复自主呼吸后，PaO2值显著降低，P(A-a)O2值显著升高。与侧卧的马匹相比，所有仰卧的马匹以及与IPPV的马匹相比，自主呼吸的马匹的PaO2值最低，P(A-a)O2值最高。pH变化与PaCO2变化平行。还评估了所有组中右侧卧与左侧卧时的血气值。与右侧卧（LRRG1）的马匹相比，左侧卧（LRLG1）的马匹在自主呼吸时PaO2值显著降低，P(A-a)O2值显著升高。（摘要截取自400字）
