A Clinical Study On The Ability Of Ultrasonographic Evaluation Of The Excursion Of The Diaphragm To Predict Weaning From Mechanical Ventilation In ICU Patients

Objective:The objective of this study was to use ultrasound to evaluate the excursion of the diaphragm, analyze the value in predicting successful weaning from mechanical ventilation in ICU patients, and compared with the physiological parameters of inspiratory muscle.Methods:This study included 98 patients who with respiratory failure need for mechanical ventilation(≥48 hours) in the comprehensive ICU of Hebei Forth Medical University Hospital from June 2014 to December 2014, 73 cases of male and 25 cases of female. The patients were classified into a success group or a failure group according to the weaning outcome. After the primary disease and respiratory failure had been removed, the patients reached weaning process. We measured P0.1 and MIP, the patient’s rapid shallow breathing index(RSBI) and P0.1/MIP were simultaneously calculated. Patients underwent T-piece spontaneous breathing. At the start of the 1-hour SBT, with the patient in the supine position, each hemidiaphragm was evaluated measured by a single well-trained doctor with a 3.5-MHz ultrasonography probe placed along in the right anterior axillary line and the left midaxillary line for measurement of liver and spleen displacement using an GE ultrasound machine( GE, VIVID_I, U.S.A). The ultrasound beam was directed to the hemidiaphragmatic domes at an angle of ≥70°. Three measurements were recorded and averaged for each side. The whole ultrasonography examination was accomplished in 5 mins. Other parameters collected were factors that could affect weaning: underlying diseases(diabetes mellitus, thyroid dysfunction, chronic obstructive pulmonary disease, and acute respiratory distress syndrome), ventilation time, and relevant blood biochemistry findings. The efficacy of ultrasonographic diaphragmatic function in predicting weaning failure. Attending physicians were blind to the ultrasonography results. All the data were collected and analyzed by the statistical program SPSS 16.0. The agreement between ultrasonography diaphragmatic excursion and P0.1、MIP、P0.1/MIP was evaluated by Cohen’s k coefficient. The ROC curves were calculated and compared with Medcalc 11.4 software.Results:1 This study included 45 patients, 39 cases of male(74%),the mean age was 67 years(range, 32 to 88 years). Of all patients, the most common cause of acute respiratory failure was pneumonia(32 patients, 32%), ARDS(32 patients, 32%), follow by heart failure(12 patients, 12%), AECOPD(10 patients, 10%), pulmonary thromboembolism(6 patients, 6%), cardiopulmonary resuscitation(4 patients, 4%), stroke(2 patients, 2%).2 The patients were classified into a success group or a failure group according to the weaning outcome, 74 patients were successfully weaning and 24 patients were failed. There was no significant difference between two groups of patients with age, the acute physiology and chronic health evaluation II(APACHE II), sequential Organ Failure Assessment(SOFA),( P=0.653,P=0.164,P=0.129). Compared with the success group,patients in the failure group had longer ventilation time, ICU and hospital lengths of stay,( P=0.024,P<0.001,P=0.02). There was no significantdifference between two groups of patients with MIP、 P0.1/MIP,( P=0.547,P=0.098), but P0.1, RSBI, left diaphragmatic excursion, right diaphragmatic excursion and mean value of left and right diaphragmatic excursion had significant difference,( P=0.047,P=0.002,P<0.001,P<0.001,P<0.001).3 Application of diaphragmatic excursion and VT yielded similar efficacy in predicting weaning outcome and the agreement of these two methods was poor(Kappa=0.190). Application of diaphragmatic excursion and MIP yielded similar efficacy in predicting weaning outcome and the agreement of these two methods was poor(Kappa=-0.071). Application of diaphragmatic excursion and P0.1 yielded similar efficacy in predicting weaning outcome and the agreement of these two methods was poor(Kappa=0.158). Application of diaphragmatic excursion and P0.1/MIP yielded similar efficacy in predicting weaning outcome and the agreement of these two methods was poor(Kappa=0.169).4 The cutoff value of diaphragmatic excursion for predicting successful extubation was determined to be 1.14 cm by receiver operated characteristic curve analysis. Using this cutoff value, the sensitivity and specificity of diaphragmatic excursion to predict successful weaning were 89.2% and 75%, respectively. Area under the curve is 0.849. The cutoff value of left diaphragmatic excursion for predicting successful extubation was determined to be 0.86 cm by receiver operated characteristic curve analysis. Using this cutoff value, the sensitivity and specificity of diaphragmatic excursion to predict successful weaning were 70.3% and 70.8%, respectively. Area under the curve is 0.759; The cutoff value of right diaphragmatic excursion for predicting successful extubation was determined to be 1.18 cm by receiver operated characteristic curve analysis. Using this cutoff value, the sensitivity and specificity of diaphragmatic excursion to predict successful weaning were 85.1% and 62.5%, respectively. Area under the curve is 0.768. The sensitivity and specificity of diaphragmatic excursion were superior to P0.1, MIP, P0.1/MIP, RSBI.5 Of the 98 patients, the mean diaphragmatic excursion was 1.40±0.61 cm, whereas the mean values of left and right diaphragmatic excursion were 0.99±0.90 cm and 1.70±0.81 cm, respectively. There was no significant difference between left and right diaphragmatic excursion, and the correlation between them was poor. Ultrasonographic diaphragmatic dysfunction was diagnosed if an excursion was <10 mm or negative. There were 60 patients with diaphragmatic dysfunction, among them 35 patients were after chest surgery, unilateral dysfunction was more common than bilateral, and 10 patients had paradoxical movements. Ultrasonography diaphragmatic excursion was not with age, hight, weight, body mass index. Compared with normal diaphragmatic function patients, patients with diaphragmatic dysfunction had significantly longer ventilation time, intensive care unit length of stay and hospital length of stay. Of the 24 patients in the failure group, 21 patients had diaphragmatic dysfunction: unilateral in six, bilateral in eight, and 7 patients had paradoxical movements.Conclusion:1 Diaphragmatic dysfunction is common in the ICU. Patients with diaphragmatic dysfunction were more likely to fail weaning and prolong ventilation time.2 Ultrasonography is a noninvasive technique, which has proved to be an accurate, safe, easy to use bedside modality. Bedside ultrasonography has become a valuable tool in the evaluation of diaphragm function and early finds out diaphragmatic dysfunction. It will be is a good predictor for weaning outcome and may be superior to the physiological parameters of inspiratory muscle and traditional parameters.3 Combining critical ultrasound and physiological parameters of inspiratory muscle and traditional parameters will be more beneficial to predict successful weaning from mechanical ventilation in ICU patients.