Wilson D V, Suslak L, Soma L R
Department of Anesthesia, University of Pennsylvania School of Veterinary Medicine, Kennett Square, PA 19348.
Am J Vet Res. 1988 Aug;49(8):1263-9.
Cardiovascular effects and pulmonary gas exchange were compared during conventional mechanical ventilation (CMV) and interrupted high-frequency, positive-pressure ventilation (IHFPPV) in 6 anesthetized ponies in dorsal recumbency. When the peak airway pressure (Paw) was held constant at control values attained during CMV (18 to 20 cm of H2O), and the ventilator frequency of IHFPPV was varied over the range, 2.5 to 12.5 Hz, significant (P less than 0.05) changes from control values were observed only in the ratio of dead-space volume to tidal volume (VD/VT) and in the respiratory minute volume (VE). The mean (+/- SEM) carbon dioxide excretion (VCO2) was 2.12 +/- 0.1 ml/kg/min during IHFPPV. Dead-space ventilation ranged from 40 to 73.7% of total ventilation and increased directly with increasing frequency. The VE also increased, from 89 ml/kg/min at a ventilatory frequency of 2.5 Hz to 145 ml/kg/min at a frequency of 12.5 Hz. Maintaining the frequency of IHFPPV constant at 12.5 Hz and increasing the Paw over the range of 5 to 30 cm of H2O caused significant (P less than 0.05) changes in arterial partial pressure of O2 (PaO2), VCO2, pulmonary shunt fraction (QS/QT), VE, arterial-alveolar differences in oxygen tension (AaDO2), VD/VT, and cardiac output, compared with CMV. The PaO2 and the VCO2 increased linearly with increasing Paw. With increasing Paw, VD/VT decreased directly with increasing Paw from 98 to 69.3%. Gas exchange at a Paw of 15 cm of H2O during IHFPPV was equivalent to conditions at Paw of 20 cm of H2O during CMV. At a higher Paw during IHFPPV, improvements over control values were observed in gas exchange.
对6匹处于背卧位的麻醉小马，在传统机械通气（CMV）和间断高频正压通气（IHFPPV）期间的心血管效应和肺气体交换进行了比较。当气道峰值压力（Paw）维持在CMV期间达到的对照值（18至20 cmH₂O）不变，且IHFPPV的通气频率在2.5至12.5 Hz范围内变化时，仅在死腔容积与潮气量之比（VD/VT）和每分通气量（VE）方面观察到与对照值有显著（P<0.05）变化。IHFPPV期间平均（±SEM）二氧化碳排出量（VCO₂）为2.12±0.1 ml/kg/min。死腔通气占总通气量的40%至73.7%，并随频率增加而直接增加。VE也增加，从通气频率2.5 Hz时的89 ml/kg/min增加到频率12.5 Hz时的145 ml/kg/min。将IHFPPV的频率维持在12.5 Hz不变，并将Paw在5至30 cmH₂O范围内增加，与CMV相比，动脉血氧分压（PaO₂）、VCO₂、肺分流分数（QS/QT）、VE、动脉-肺泡氧分压差（AaDO₂）、VD/VT和心输出量均出现显著（P<0.05）变化。PaO₂和VCO₂随Paw增加呈线性增加。随着Paw增加，VD/VT随Paw增加而直接降低，从98%降至69.3%。IHFPPV期间Paw为15 cmH₂O时的气体交换与CMV期间Paw为20 cmH₂O时的情况相当。在IHFPPV期间较高的Paw下，气体交换相对于对照值有所改善。
