流量波形触发技术在慢性阻塞性肺疾病合并撤机困难患者中的应用研究

Effects of the flow waveform method of triggering in weaning from mechanical ventilation for COPD patients

目的观察不同流量触发机制对撤机困难的呼吸衰竭患者在压力支持通气(PSV)时通气参数的影响。方法呼吸衰竭患者23例,其中男性16例,女性7例,年龄(68±6)岁。基础疾病均为慢性阻塞性肺疾病(COPD)。所有患者均为接受有创人工气道(气管插管/气管造口)及机械通气支持1周以上者,在治疗过程中病情稳定准备进行自主呼吸试验(spontaneous breathing trial,SBT)。分别在标准流量触发(2L/min)和流量波形触发机制下通气支持30min(PS10cmH2O),监测患者的呼吸力学参数[包括潮气量(VT)、呼吸频率(RR)、分钟通气量(MV)、气道闭合压(P0.1)、浅快呼吸指数(RSBI)和压力时间乘积(PTPt)等]及动脉血气分析,并观察流量波形触发技术对撤机的影响。结果2例患者因生理学参数不稳定而终止SBT试验。其余21例在采用流量波形触发PSV支持30min后,RR、MV和RSBI均出现显著增加(P<0.05),但VT、P0.1却无明显变化。继续通气支持24h后,RR、MV和RSBI与采用流量波形触发PSV支持30min时相比无显著改变,PTPt和P0.1却呈显著降低,动脉血二氧化碳分压(PaCO2)也逐渐降低。采用流量波形触发PSV支持3～7d后,21例患者成功撤机。结论流量波形触发技术能显著减少COPD呼吸衰竭患者的自主吸气做功,改善人机同步性,提高撤机成功率。

Objective To evaluate the effect of flow wavefrom method on chronic obstractive pulmonary disease （COPD） patients in weaning pressure support ventilation （PSV）. Methods Twenty-three intubated （at least one week） stable patients [male 16 and female 7 ,mean age （68 ± 6） years ,arterial oxygen tension/inspiratory oxygen fraction （PaO2/FiO2） ≥ 200 mmHg] recovering from acute exacerbation of COPD were studied with varying triggering [flow waveform method or traditional flow triggering （2 L/min）] at 10 cmH2O of pressure support in random order. Respiratory mechanics [Including tidal volume （VT）, respiratory rate （RR）,minute ventilation （MV）,compliance and airway resistance] were monitored. Also the airway occlusion pressure （Pal） ,pressure time product of triggering （PTPt）, rapid shallow breath index （RSBI）, arterial blood gas analysis were measured. Results Two patients were failed with PSV because of unstable vital signs. The other patients＇ RR and MV were significantly increased after PSV support 30 min with flow waveform method. The flow waveform method of triggering was more sensitive to patient than traditional flow triggering, resulting in less Pal and PTPt after 24 bour（P 〈 0.05 ）. No difference was found with PaO2/FiO2 ratio, but arterial carbon dioxide tension （PaCO2） decreased remarkablely in 24 hour. All of 21 patients succeeded in weaning within 3 - 7 days. Conclusion The flow waveform method of triggering improves the patient＇s respiratory rate and decreases the work of breathing during the inspiratory triggering phase. This system is more sensitive thus it may be suitable for some difficult from weaning patients.