Piva J, Chatrkaw P, Choong K, Frndova H, Cox P
Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brazil.
J Pediatr (Rio J). 2000 Sep-Oct;76(5):349-56. doi: 10.2223/jped.73.
(a) to evaluate the effect on oxygenation and ventilation of rabbits with induced surfactant depletion when they are submitted to a conventional mechanical ventilation, plus a small dose of exogenous surfactant; (b) to compare this group with another group submitted to a High Frequency Oscillation (HFO) without exogenous surfactant administration.METHODS: Twenty New Zealand White rabbits weighing (-/+ 3 kg) were anaesthetized and artificially induced to a endogenous surfactant depletion by successively lung lavage with normal saline (aliquots of 25 ml/kg) until to reach a persistent PaO(2) less than 100 mmHg when submitted to a mechanical ventilation in a pressure control mode with a target tidal volume of 10ml/kg, PEEP of 5cm H(2)O, FiO(2) 1.0, respiratory rate 30/min, and inspiratory time of 0.65 s. Then the rabbits were divided in (a) CMV+S group, submitted to a conventional mechanical ventilation plus exogenous surfactant replacement; (b) HFO group, submitted to a High Frequency Oscillation Ventilation. Arterial blood gases were measured at control period, post lung lavage, 15, 16 and 120 minutes after treatment started. The groups were compared using Student t test.RESULTS: The post lung lavage PaO(2) in both groups was lower than 50mmHg (p=0.154), increasing after 15 min of treatment to 254 mmHg (CMV+S) and 288 mmHg (HFO, p=0.626). The PaO(2) at 60 and 120 minutes were higher (p=0.001) in the HFO group (431 e 431 mmHg) when compared with the CMV+S group, which showed a progressive fall (148 e 126 mmHg). At 60 minutes of treatment, the PaCO(2) was lower (p=0.008) in the CMV+S group (29 versus 41 mmHg).CONCLUSIONS: In ARDS animal model a protect mechanical ventilation strategy as HFO by itself promotes a fast and persistent increase in the oxygenation, with superior levels than those observed in animals treated with conventional mechanical ventilation plus exogenous surfactant replacement.
（a）评估诱导表面活性剂耗竭的家兔在接受传统机械通气加小剂量外源性表面活性剂时对氧合和通气的影响；（b）将该组与另一组接受高频振荡（HFO）且未给予外源性表面活性剂的家兔进行比较。方法：20只体重（-/+ 3千克）的新西兰白兔麻醉后，通过用生理盐水（25毫升/千克等分试样）连续肺灌洗诱导内源性表面活性剂耗竭，直到在压力控制模式下进行机械通气时，目标潮气量为10毫升/千克、呼气末正压为5厘米水柱、吸入氧浓度为1.0、呼吸频率为30次/分钟、吸气时间为0.65秒时，持续动脉血氧分压（PaO₂）低于100毫米汞柱。然后将兔子分为：（a）CMV+S组，接受传统机械通气加外源性表面活性剂替代；（b）HFO组，接受高频振荡通气。在对照期、肺灌洗后、治疗开始后15、60和120分钟测量动脉血气。使用学生t检验比较两组。结果：两组肺灌洗后的PaO₂均低于50毫米汞柱（p = 0.154），治疗15分钟后分别升至254毫米汞柱（CMV+S组）和288毫米汞柱（HFO组，p = 0.626）。与CMV+S组相比，HFO组在60和120分钟时的PaO₂更高（p = 0.001），CMV+S组呈逐渐下降趋势（148和126毫米汞柱）。治疗60分钟时，CMV+S组的二氧化碳分压（PaCO₂）更低（p = 0.008）（29对41毫米汞柱）。结论：在急性呼吸窘迫综合征（ARDS）动物模型中，像高频振荡这样的保护性机械通气策略本身能促进氧合快速持续增加，其水平优于接受传统机械通气加外源性表面活性剂替代治疗的动物。
