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目的观察比例辅助通气(PAV)和同步间歇指令通气(SIMV)治疗幼兔重症胎粪吸入综合征(MAS)时相关参数的变化。方法将30只20～30 d日龄健康日本大耳兔随机分为4组:(1)PAV组(n=8),灌入胎粪混悬液后予PAV通气;(2)SIMV组(n=8),灌入胎粪后实施SIMV通气;(3)MAS组(n=8),胎粪灌入后不予通气但予持续氧气(500 mL·L-1)吸入;(4)对照组(n=6),灌入9 g·L-1盐水后予持续氧气(500 mL·L-1)吸入。分别于灌注前、灌注后0.5 h及通气1 h、2 h、3 h、4 h、5 h、6 h、7 h、8 h记录各组循环参数及呼吸力学参数,包括心率、呼吸频率、潮气量、呼吸道峰压(PIP)、平均呼吸道压(MAP)。灌注前(0点)和灌注后0.5 h(0’点)、通气4 h及通气8 h检测动脉血气,并计算动脉/肺泡氧分压比值(a/APO2)。结果 PAV组和SIMV组4 h、8 h动脉血二氧化碳分压在正常范围;PAV组和SIMV组4 h、8 h a/APO2值均较0’点升高(Pa<0.05);PAV组与SIMV组在各时间点a/APO2值差异均无统计学意义(Pa>0.05);在通气过程中,SIMV组PIP及MAP较PAV组高,差异均有统计学意义(Pa<0.05)。PAV组和SIMV组心率相近,各时间点变化不大,差异无统计学意义(P>0.05)。结论 PAV能在较短时间内有效改善幼兔重度胎粪吸入时肺部氧合状态;在取得同样的血气值和氧饱和度情况下,与SIMV相比,PAV治疗幼兔MAS时PIP及MAP较低;PAV对幼兔重度胎粪吸入时的心率影响较小。
Objective To observe the changes of relevant parameters in the treatment of severe meconium aspiration syndrome (MAS) in young rabbits with proportional assisted ventilation (PAV) and synchronized intermittent mandatory ventilation (SIMV). Methods Thirty healthy Japanese white rabbits aged from 20 to 30 d were randomly divided into 4 groups: (1) PAV group (n = 8), which were infused with meconium suspension to ventilate PAV; (2) SIMV group n = 8). SIMV ventilation was administered after meconium was infused. (3) In MAS group (n = 8), meconium was infused without continuous ventilation but infused with continuous oxygen (500 mL·L-1) The control group (n = 6) was infused with continuous oxygen (500 mL · L-1) after 9 g · L-1 saline was infused. The parameters of circulation and mechanical parameters of respiration, including heart rate, respiration rate, respiration rate and blood pressure, were recorded before perfusion, 0.5 h after ventilation and 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, Tidal volume, peak airway pressure (PIP), mean respiratory pressure (MAP). Arterial blood gas was measured before perfusion (0:00) and 0.5 h (0 ’) after perfusion, ventilation for 4 hours and ventilation for 8 hours, and the arterial / alveolar oxygen ratio (a / APO2) was calculated. Results The partial pressure of arterial carbon dioxide in PAV group and SIMV group was normal at 4 h and 8 h respectively. The values of 4 h and 8 ha / APO2 in PAV group and SIMV group were all higher than those in 0 ’point group (P <0.05) There was no significant difference in a / APO2 between groups at each time point (P> 0.05). During ventilation, PIP and MAP in SIMV group were significantly higher than those in PAV group (P <0.05). The heart rate of PAV group and SIMV group were similar, with little difference at each time point, the difference was not statistically significant (P> 0.05). Conclusions PAV can effectively improve pulmonary oxygenation in young rabbits with severe meconium aspiration in a relatively short period of time. Compared with SIMV, PAV treatment of young rabbits MAS with PIP and MAP PAV had little effect on the heart rate of rabbits with severe meconium aspiration.