高频振荡通气与呼气末正压递增法联用对吸入性损伤犬呼吸循环功能的影响

Effects of high frequency oscillatory ventilation combined with incremental positive end-expiratory pressure on respiratory and circulatory functions of dogs with inhalation injury

目的探时高频振荡通气（HFOV）联合呼气末正压递增法（iP）对烟雾吸人性损伤犬呼吸、循环功能及肺组织学的影Ⅱ向。方法将12只犬常规机械通气后制成苇度烟雾吸人性损伤模型，按随机数宁表法分为2组：HFOV纰和HFOV＋IP组，每组6只，分别行相应通气治疗8h。于伤前、致伤后即刻及治疗2、4、6、8h分别记录2组犬血气分析指标（pH值、PaO2PaCO，水平）和血流动力学参数[心率、平均动脉压（MAP）、肺动脉压（PAP）、中心静脉膻（CVP）、心排血量（CO）]。于治疗8h后处死2组犬，另处死1只未经任何处理的正常犬和1只未经后续处理的烟雾吸人性损伤犬。对上述犬行肺组织病理学观察，刘2组火行肺损伤程度评分。对数据行秩和检验、重复测谴方差分析、LSD—t检验；结果（1）2组犬致伤后即刻PaO，水平与组内伤前值比较均娃著降低（t值分别为4．960、5．310，P值均小于0．01）；2组犬治疗各时相点，PaO，水平与组内致伤后即刻水平比较均艋著升高（t值为4．930～6．050，P值均小于0．01）。治疗2、4、8h，HFOV＋IP组犬PaO，水平均显著高于HFOV组水平（f值为3．775～5．774，P值均小于0．01）；2组犬pH值、PaCO，水平在各时相点比较差异均无统计学意义（t值为0．002～0．997，P值均大于0．05）。（2）2组犬MAP、PAt、CVP水平组内各时相点比较均未见明硅变化（F值为1．316～4．959，P值均大于0．05）；HFOV组治疗各时相点心率水平与组内致伤后即刻水平比较均娃蒋降低（t值为3．780～8．970，P值均小于0．01）；HFOV＋IP组治疗4、6、8h，CO水平与组内致伤后即刻比较均明显降低（t值为3．990～11．200，P值均小于0．01）。2组犬比较，同一时相点MAP、PAP、CVP等廊流动力学参数水平接近（t值为0．089～2．123，P值均大于0．05）；治疗4、6、8h，HFOV＋IP组心率水平高于HFOV组（t值为2．931～7．229，P〈0．05或P〈0．01），CO水平均旺著低于HFOV组（t值为4．297～11．206，P值均小于0．01）。（3）与正常犬比较，HFOV组和HFOV＋IP组犬肺泡腔内出现炎性细胞浸润及出血，但较烟雾吸人性损伤犬均有不同稃度减轻；与HFOV组比较，HFOV＋IP组肺泡腔内炎性细胞浸润明鼹减少，肺泡结构相对完整，肺泡蹙末见增厚。HFOV组和HFOV＋1P组肺组织损伤评分分别为（3．27±0．24）、（2．79±0．31）分，差异有统计学意义（t=27，P〈0．05）。结论HF’OV联合IP对吸人性损伤犬血气分析指标和血流动力学参数无不良影响，能够改善气体交换，减轻肺组织损伤，是目前治疗吸人性损伤较为适当的通气模式。

Objective To study the effects of high frequency oscillatory ventilation （HFOV） com- bined with incremental positiw end-expiratory pressure （IP） on respiratory and circulatory functions, and lung histopathology of dogs with smoke inhalation injury. Methods After being treated with conventional mechanical ventilation, 12 dogs were inflicted with severe smoke inhalation injury and divided into group HFOV and group HFOV ＋ IP according to the random number tahle, with 6 dogs in each group. Then theyreceived corresponding ventilation for 8 hours respectively. Blood gas analysis results （pH value, PaOz and PaCO2 levels） and hemodynamic parameters [ heart rate, mean arterial pressure （MAP） , pulmonary arterial pressure （PAP） , central venous pressure （CVP） , cardiac output （CO） ] were recorded before injury, im- mediately after injury, and at post ventilation hour （PVH） 2, 4, 6, and 8. The dogs of two groups were sacrificed at PVH 8. A healthy dog without any treatment and a dog with smoke inhalation injury but no subsequent treatment were sacrificed in addition. Lung tissues of all dogs were obtained for histopathologieal observation. Lung injury score examination was conducted in both groups. Data were processed with rank sum test, analysis of variance of repeated measurement, and LSDt test. Results （ l ） The PaOz levels in both groups were significantly decreased immediately after injury, compared with those before injury （with t values respectively 4. 960, 5. 310, P values all below 0.01 ）. The PaO2 levels in both groups from PVH 2 to PVH 8 were significantly increased, compared with those observed immediately after injury （with t values from 4. 930 to 6.050, P values all below 0.01 ）. At PVH 2, 4, and 8, PaO2 levels in group HFOV ＋ IP were significantly higher than those in group HFOV （with t values from 3. 775 to 5. 774, P values all below 0.01 ） ; no statistically significant differences were observed in pH value and PaCO2 level at each time point between two groups （with t values from 0. 002 to 0. 997, P values all above 0.05）. （2） There were no sta- tistically significant differences in MAP, PAP, and CVP within two groups at each time point （with F values from 1. 316 to 4. 959, P values all above 0.05 ）. In group HFOV, heart rate from PVH 2 to PVH 8 was sig-nificantly lower than that observed immediately after injury （with t values from 3. 780 to 8. 970, P values all below 0.01 ）. In group HFOV ＋ IP, CO at PVH 4, 6, and 8 was significantly lower than that observed im- mediately after injury （with t values from 3. 990 to 11. 200, P values all below O. 01 ）. There were no statisti- cally significant differences in MAP, PAP, and CVP between two groups at the same time point （with t val- ues fromO. 089 to 2. 123, Pvalues all above0.05）. At PVH4, 6, and 8, heart rate in group HFOV ＋IP was higher than that in group HFOV （with t values from 2. 931 to 7. 229, P 〈0.05 orP 〈0.01） , while CO was lower （ with t values from 4. 297 to 11. 206, P values all below 0.01 ）. （3） Compared with those of the healthy dog, inflammatory cell infiltration and bleeding in the lung were observed in alveolar space in both group HFOV and group HFOV ＋ IP, while the degree was less serious than that of the dog with smoke inhala- tion injury only. Compared with those of group HFOV, inflammatory cell infiltration in group HFOV ＋ IP was less significant, the alveolar structure was relatively intact, and no thickening of alveolar walls was observed. The lung injury score in group HFOV [ （3.27 ± 0.24） pointsl was higher than that of group HFOV ＋ IP I （ 2.79 ± 0.31 ） points, t = 27, P 〈 0.05 1 Conclusions HFOV combined with IP can improve gas exchange and alleviate puhnonary injury without any adverse effect on blood gas analysis or hemodynamic parameters. Therefore, it may be considered as an appropriate mode of ventilation for the treatment of smoke inhalation injury.