机构地区:[1]上海交通大学附属第一人民医院呼吸科,上海200080 [2]上海交通大学附属第一人民医院急诊科,上海200080
出 处:《中国呼吸与危重监护杂志》2005年第6期425-428,共4页Chinese Journal of Respiratory and Critical Care Medicine
摘 要:目的比较压力控制通气(PCV)与压力支持通气(PSV)对慢性阻塞性肺疾病(COPD)呼吸衰竭患者的通气参数的影响.方法 COPD所致呼吸衰竭患者35例,在给予常规内科治疗的同时,使用口鼻面罩分别接受持续气道正压(CPAP)、PSV和PCV模式通气各60 min.PCV时采用辅助/控制(A/C)模式,监测患者的吸气流速和气道压力变化,以调整预置吸气时间(TI),通气频率(f)为6次/min,吸气压力(Pinsp)为12~20 cm H2O,呼气末气道正压(PEEP)为4 cm H2O,吸气触发灵敏度(trigger)为2 L/min,偏流(bias flow)为20 L/min,吸入氧浓度(FiO2)为0.4~0.5;PSV时的压力支持水平(PS)为8~16 cm H2O(即Pinsp-PEEP),最大吸气时间限制(Timax)为3 s,其余参数保持不变.监测潮气量(VT)、TI、每分通气量(MV)、吸气/呼吸周期时间比(TI/Ttot)和呼吸频率(RR),计算浅快呼吸指数(RSBI),并采集动脉血作血气分析.结果患者在接受PSV和PCV通气时的VT均明显高于CPAP时,RR逐渐减慢(P<0.05);PCV时的MV明显低于PSV与CPAP时.PCV时的TI较PSV和CPAP时明显延长[(1.23±0.09)s与(1.06±0.11)s、(0.89±0.10)s,P<0.05],PCV与PSV时的TI/Ttot较CPAP时减小;浅快呼吸指数(RSBI)从CPAP时的(78.2±4.9)breaths·min-1·L-1降至PSV时的(44.9±2.6)breaths·min-1·L-1和PCV时的(35.6±1.9)breaths·min-1·L-1(P<0.05).PSV和PCV模式时的PaO2/FiO2明显高于CPAP时(264.5±72.3、273.1±71.2与221±56.4,P<0.05),三种模式下的PaCO2均无显著性差异.结论与PSV相比,应用PCV治疗呼吸衰竭时通过预置适宜的TI及备用通气频率,能在与PSV相同的气道压的前提下提供相近的VT及MV;PCV不仅有助于调控患者的呼吸频率,提供必要的通气支持,还有利于减轻患者呼吸肌的作功.Objective To compare the effects of two noninvasive positive pressure ventilation (NPPV) modes, pressure control ventilation (PCV) and pressure support ventilation ( PSV), on respiratory mechanics in patients with respiratory failure due to chronic obstructive pulmonary disease (COPD). Methods 35 conscious patients with respiratory failure due to acute exacerbations of chronic obstructive pulmonary disease (AECOPD) were ventilated by NPPV via face mask for at least 1 hour. Continuous positive airway pressure (CPAP) mode was applied at first in all patients with a bias flow of 20 L/min and positive end expiratory pressure (PEEP) of 4 cm H2O. Then the patients were ventilated with PCV or PSV mode at random. Inspiratory time(TI) during PCV was preset and regulated by observing the waveform. Respiratory mechanics and arterial blood gas(ABG) were measured at 60 min after ventilation of different modes. Results Compared with CPAP and PSV, minute ventilation (MV) and respiratory rate (RR) were much lower in PCV mode ( all P 〈 0.05 ), but T1 during PCV was much longer than those during PSV and CPAP[ ( 1.23±0.09) sec versus ( 1.06±0. 11 ) sec and (0.89± 0.10)sec, P 〈 0.05]. Inspiratory duty cycle (T1/Ttot) and rapid shallow breath index (RSBI) during PCV and PSV were obviously decreased while tidal volume(VT) was markedly increased ( all P 〈 0.05). No difference of PaO2/FiO2 in PSV and PCV was found. Conclusions By adjusting the T1 and back-up rate, PCV is capable of reducing patient workload and provides similar level of respiratory support with PSV under the same airway pressure. Compared with PSV, PCV reduces the patients work of breathing (WOB)more effectively, however, the difference of oxygenation improvement is not significant.
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