不同干预措施对犬急性肺损伤早期呼吸应答和呼吸做功的影响

目的 探讨早期应用控制性高浓度氧疗、持续气道内正压(CPAP)、双水平气道内正压(BiPAP)不同的干预措施对急性肺损伤(ALI)早期呼吸应答和呼吸做功的影响.方法 24只杂种犬在制作油酸ALI模型成功后(PaO2/FiO2≤300mmHg),保持自主呼吸,随机进入:(1)控制性高浓度氧疗组(n=8);(2)CPAP组(n=8);(3)BiPAP组(n=8).连续记录并计算正常、ALI早期、干预后1～4h内呼吸应答和呼吸做功各项生理指标.结果 在降低呼吸频率和浅快呼吸呼吸指数上,BiPAP组效果最明显(P＜0.001),其次是CPAP组和氧疗组(P＜0.001).3组对分钟通气量的影响不大(P＞0.05),维持在ALI/ARDS发生后的通气水平.在潮气量、平均吸气流量指标的改善上,BiPAP组效果最显著,其次是CPAP组和氧疗组.3组在吸气时间占呼吸周期比值上无显著性差异(P＞0.05).在跨膈压峰值上,BiPAP组降低最明显,其次是CPAP组.CPAp组和BiPAP组可有效地抵消内源性PEEP(P＜0.01),氧疗组对于内源性PEEP改善不显著(P＞0.05).在降低吸气做功上,BiPAP组最显著,其次是CPAP组,氧疗组呼吸功耗与干预前比较无显著性差异.CPAP组(P＜0.01)和BiPAP组(P＜0.05)有效地降低了克服内源性PEEP成分做功的比例.结论 BiPAP和CPAP对于缓解呼吸窘迫、减少呼吸功耗、改善呼吸应答均具有积极作用,显著延缓了ALI/ARDS的病情恶化,其中BiPAP效果更为显著.

Effects of different interventions for early-stage acute lung injury on respiratory response and work of breathing in canine model

OBJECTIVE: To evaluate the effects of different interventional strategies, namely controlled high-concentration oxygen therapy, continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP) ventilation, on respiratory response and work of breathing (WOB) in canine models of early-stage acute lung injury (ALI). METHODS: After successful duplication of ALI models with oleic acid (diagnostic criteria: Pa(O2)/Fi(O2)0.05), which maintained the level of early ALI/ARDS stage. BiPAP greatly improved V(T) and V(T)/Ti, showing better effects than CPAP and O2. No significant differences were noted among the 3 groups in T(I)/T(tot) (P>0.05). BiPAP showed superior effect to CPAP in lowering the peak transdiaphragmatic pressure (Pdi). CPAP and BiPAP both effectively counteracted intrinsic positive end expiratory pressure (PEEPi) (P<0.01), while O2 produced no obvious such effects (P>0.05). BiPAP showed the most evident effects, followed by CPAP, in reducing WOB, but oxygen therapy produced no obvious effects. CPAP (P<0.01) and BiPAP (P>0.05) both effectively reduced the proportion of ingredients in WOB related to PEEPi. CONCLUSION: BiPAP and CPAP can produce favorable effects in relieving dyspnea, reducing WOB and improving respiratory response to control the deterioration of ARDS. BiPAP has more significant therapeutic effects than CPAP and oxygen therapy.