Effects Of Muscle Relaxation Depth On Respiratory Mechanics And Hemodynamics In Patients With Severe Acute Respiratory Distress Syndrome

Background:Currently,muscle relaxation therapy is an important treatment for patients with severe acute respiratory distress syndrome（ARDS）.The depth of muscle relaxation therapy may affect the efficacy of muscle relaxation agents for ARDS.How to optimize the dose of neuromuscular blockers to achieve appropriate depth of muscle relaxation is an important part of clinical treatment of ARDS.Because of its rapid onset and short duration,atracurium is commonly used for the treatment of muscle relaxation in patients with severe ARDS.The muscle relaxation detection train of four stimulation（TOF）is currently used for clinical evaluation of the depth of neuromuscular block and can be applied to optimize the dose of neuromuscular blocker in patients with severe ARDS.Therefore,to explore the effects of atracurium induced different depths of muscle relaxation on respiratory mechanics and hemodynamics in patients with severe ARDS will provide a certain clinical basis for the clinical guidance of optimal treatment of muscle relaxation in patients with severe ARDS.Objective:To study the effects of different depth of muscle relaxation on respiratory mechanics and hemodynamics in patients with severe ARDS,and to explore the optimal depth of muscle relaxation for treatment of severe ARDS.Methods:This study was a prospective randomized controlled clinical trial involving102 patients who met the diagnostic criteria for severe ARDS in Qingdao Chengyang People’s Hospital.Patients who met the inclusion criteria were randomly divided into two groups according to the random number table:In the first group,deep muscle relaxation（n=52）,patients did not respond to stimulation with atracurium and achieved deep muscle relaxation,i.e.muscle relaxation detection quad training stimulation（TOF）=0;In the second group,the superficial muscle relaxant group（n=50）,patients with atracurium had two effective responses to TOF stimulation,TOF=2.Pa O₂/Fi O₂,inspiratory platform pressure（Pplat）,mean arterial pressure（MAP）,heart rate（HR）,mechanical ventilation time,intensive care unit（ICU）hospitalization time and other related indexes were recorded Before muscle relaxation intervention,when muscle relaxation target was reached（T0）and 2 hours after muscle relaxation target was reached（T2h）.Measurement data was expressed as mean±standard deviation,and enumeration data was expressed as rate.Chi-square test was used for comparison of rate,and t test was used for comparison of measurement data between groups.P<0.05 indicated statistically significant difference.Results:The dose of atracurium in two groups was 5.2 ug/kg·min in the deep muscle relaxation group and 3.6 ug/kg·min in the superficial muscle relaxation group（P<0.05）.When the target depth of muscle relaxation was reached（T0）and 2 hours after the target of muscle relaxation was reached（T2h）,the platform pressure（Pplat）was significantly decreased P<0.05),and the oxygenation index（Pa O₂/Fi O₂）was significantly increased（P<0.05）in 2 groups.There were no significant differences in PPLAT and Pa O₂/Fi O₂between T0 and T2H in deep muscle relaxation group（P>0.05）.There were no significant differences in PPLAT and Pa O₂/Fi O₂between T0 and T2H in the superficial muscle relaxation group（P>0.05）.Furthermore,19 patients（37%）in the deep muscle relaxation group and 25 patients（50%）in the shallow muscle relaxation group experienced a reduction in PPLAT of 1 c M H2O or more after treatment compared with before treatment,but there was no significant difference in the rate of significantly reduced PPLAT between the two groups（P=0.17）.There were no significant differences in systolic blood pressure,diastolic blood pressure,mean arterial blood pressure and heart rate between 2 groups after treatment with muscle relaxant at T0 and T2h compared with before intervention（P>0.05）.Compared with the superficial muscle relaxation group,the duration of mechanical ventilation and ICU stay in the deep muscle relaxation group were significantly longer（P<0.05）.There was no statistically significant difference in the incidence of adverse events between the two groups of patients treated with different depth of muscle relaxation（P>0.05）.Conclusion:Muscle relaxation therapy can improve respiratory mechanics of ARDS.There is no difference between deep muscle relaxation and superficial muscle relaxation in improving respiratory mechanics and hemodynamics,but superficial muscle relaxation can significantly shorten mechanical ventilation duration and ICU hospitalization duration in patients with severe ARDS,so superficial muscle relaxation treatment may be more beneficial for patients with severe ARDS.