The comparison of dexmedetomidine and morphine on respiratory mechanics in patients with chronic obstructive pulmonary disease during mechanical ventilation

Abstract

Objective To study the effect of dexmedetomidine(DEX) and morphine hydrochloride on respiratory mechanics in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) undergoing mechanical ventilation.Methods Forty patients of AECOPD with respiratory failure undergoing mechanically ventilated were randomly divided into two groups (n=20).The control group were treated with morphine for sedation while the experimental group with DEX.APACHE Ⅱ score,bispectral index (BIS) score,ramsay score were recorded.Respiratory mechanical parameters after sedation,and changes in vital signs as well as blood gas were compared before and after sedation.Results Compared with the control group,the mean arterial pressure (MAP) and pulse in the experimental group were decreased after sedation[(80±3) mm Hg vs (75±4) mm Hg(1 mm Hg=0.133 kPa),(90±3) bpm vs (79±3) bpm](P＜0.01).The mean airway pressure(Paw) and plateau pressure(Pplat) were significantly downregulated in experimental group [(7.5±0.7) cm H2O vs (6.2±0.6) cm H2O (1 cm H2O=0.098 kPa),(19.8±1.7) cm H2O vs (18.0±1.1) cm H2O] (P＜0.05).peak esophageal pressure (PPEAK ES) and the peak esophageal manometry reference esophagus pressure difference (dPES) was increased [(-3.4±0.7) cm H2O vs (-5.4±1.0) cm H2O,(-6.9±1.0) cm H2O vs (-9.8±1.3) cm H2O] (P＜0.01).There were no significant difference between the two groups in folding screen the end of the suction gas during transpulmonary pressure (Ptp Plat) and pulmonary static compliance (Cst)[(25.5±2.3) cm H2O vs (26.0±2.6) cm H2O,(20.5±1.9)em H2O vs (20.1±1.2) cm H2O].The airway resistance (Raw)[(20.3±0.9) cm H2O·L-1·s-1 vs (15.6±1.4) cm H2O·L1·s-1](P＜0.01)and mechanical work of breathing (WOBv)[(0.49±0.10) j/L vs (0.43±0.06) j/L](P＜0.05) were increased.The patient work of breathing (WOBp) was significantly increased [(0.11 ±0.02)j/L vs (0.16±0.04)j/L] (P＜0.01).The time of mechanical ventilation and the intensive care unit (ICU)staying time were reduced [(76±5) h vs (64±3) h、(6.0±1.5) d vs (4.6±0.9) d](P＜0.05).Conclusions DEX increased the sedative effect and lung compliance,and decreased Raw in patients undergoing mechanical ventilation compared with morphine.DEX would also unload respiratory muscle oxygen consumption estimated by reducing the inspiratory load and work of breathing. Key words: Dexmedetomidine; Chronic obstructive pulmonary disease; Mechanical ventilation; Respiratory mechanics