Application Of Ultrasound Evaluation Of Diaphragmatic Function In Neuro-intensive Care Patients During Weaning From Mechanical Ventilation

Patients with severe neurological diseases may suffer from respiratory failure due to decreased respiratory drive,diaphragm dysfunction,disturbance of consciousness,and decreased airway protection ability,requiring mechanical ventilation treatment in the neuro-intensive care unit.Prolonged mechanical ventilation increased the risk of diaphragm dysfunction and weaning failure.Diaphragm dysfunction is an important factor affecting mechanical ventilation weaning outcome.Dynamic monitoring of diaphragm structure and function by ultrasound can be used as one of the predictors of successful weaning in mechanical ventilation patients.Its advantages are noninvasive,bedside operation and dynamic.Diaphragmatic ultrasound can be used to evaluate the thickness of diaphragm,the thickening fraction of diaphragm,and the excursion of diaphragm,so as to evaluate the existence of diaphragm dysfunction and predict the success of weaning in patients with mechanical ventilation.Diaphragm ultrasound has been widely used in intensive care unit.The relevant indicators are related to protective ventilation to prevent diaphragm atrophy and guide of weaning.Diaphragmatic ultrasound used to guide rehabilitation training of stroke patients is conducive to improve the prognosis.The application of diaphragmatic ultrasound in patients with severe neurological diseases needs further study.Methods:Patients admitted to the Neurological Intensive Care Unit in our hospital from June1,2020 to January 1,2021 undergoing invasive mechanical ventilation for more than24 hours were included in this study.Among them,41 men and 12 women were divided into success group and failure group according to whether the weaning was successful or not.Spontaneous Breathing Trial（SBT）was performed when the primary disease was under control,and left and right diaphragmatic ultrasonography was performed after 30 minutes of SBT tolerance.Philips CX50（probe L12-3）was used to monitor the diaphragm function of the patients on mechanical ventilation and the diaphragm thickness was monitored and recorded at least three complete respiratory cycles in the M-mode（frequency was 14 MHz,adjusting speed was 10mm/s）after measurement lines were selected in two-dimensional ultrasound in the liver and spleen windows.Inquire clinical data,including general demographic indicators,age,previous history（hypertension,diabetes,heart disease）,smoking,alcohol consumption,and relevant laboratory tests.In this study,the diaphragmatic thickness of left and right sides was measured and the diaphragmatic thickening fraction during forced breathing was calculated to analyze the application range of diaphragmatic prediction indexes in patients with severe neurological diseases.The Receiver Operating Curve（ROC）of left,right,paralyzed and non-paralyzed subjects was described,respectively,and the value was analyzed when the optimal area under the curve（AUC）was obtained.In this study,IBM SPSSA22.0 software was used for data analysis,and Pearsonχ2 test was used for qualitative data to analyze discontinuous variables,and Fisher’s exact test was used when appropriate.The T test was used for the measurement data that fit the normal distribution,while the Mann-Whitney test was used for the measurement data that did not fit the normal distribution to compare the success group and the failure group.P<0.05 was considered statistically significant.Results:Among the 53 patients enrolled,41（77.4%）were males and 12（22.6%）were females.Cerebral infarction（31 cases,59%）,cerebral hemorrhage（9 cases,17%）,peripheral neuropathy（6 cases,11%）,myasthenia gravis（5 cases,9%）,and status epilepticus（2 cases,4%）were reported.There were 34 patients in the success group（mean age:57.53±12.72 years）and 19 patients in the failure group（mean age:61.84±11.59 years）.Weaning failure was present in 35.8%.There was no significant difference in age,risk factors（hypertension,diabetes,heart disease）,smoking and alcohol consumption.Comparison of laboratory examination indexes between the two groups showed that there was no statistically significant difference about numeration of leukocyte in blood routine examination.But the neutrophilic granulocyte percent in the failure group was higher than that in the success group,there was statistically significant difference in neutrophilic granulocyte percent（P<0.05）.Arterial blood gas analysis before weaning,including Pondus Hydrogenii（PH）,Partial Arterial Oxygen pressure（Pa O₂）,Partial Carbon Dioxide Pressure（PCO₂）,bicarbonate（HCO3-）and base excess（BE）,showed no statistical significance.But the duration of ventilatory support,NCU treatment time and the length of stay in the failure group was higher than these in the success group,there were significant differences between the two groups（P<0.05）.There was no statistically significant difference in the thickness of right and left diaphragms between the success group and the failure group（P>0.05）,while the diaphragmatic thickening fraction in the weaning failure group was lower than that in the success group,there was statistically significant difference in the diaphragmatic thickening fraction（P<0.05）.When TFDI was less than 20%,the patients were considered to have diaphragmatic dysfunction.A total of 38 patients（71.7%）had diaphragmatic dysfunction,including 24 cases in the success group and 14 cases in the failure group.The duration of mechanical ventilation in the diaphragmatic dysfunction group was higher than that in non-diaphragmatic dysfunction group（NDF）,there were statistically significant differences in the duration of mechanical ventilation between the two groups（P<0.05）,while there were no statistically significant differences in WBC count,neutrophilic granulocyte percent,NCU treatment duration and total hospital stay（P>0.05）.The AUC value of the diaphragmatic muscle on the paralyzed side was the highest,which was 0.844,and the comprehensive evaluation ability was better（P<0.05）.The corresponding cut-off value was 20.30%,the sensitivity was 0.731,and the specificity was 0.875.Conclusion:1.The rate of weaning failure in patients with severe neurological diseases is as high as 35.8%,which can prolong mechanical ventilation period,intensive care unit stay and hospital length of stay,and the potential inflammatory response may affect weaning outcomes in NCU patients.2.Diaphragmatic thickening fraction（TFdi）is an indicator to evaluate diaphragmatic function and predict the results of weaning.The incidence of diaphragmatic dysfunction in NCU patients with mechanical ventilation is high,and prolonged mechanical ventilation caused by DD may also be the reason for failure of weaning.3.In patients with severe cerebrovascular diseases manifested as hemiplegia,the comprehensive evaluation ability of the diaphragmatic ultrasound index to ptedict the weaning outcome on the paralyzed side is better.