Clinical Observation Of Diaphragmatic Ultrasonography For Predicting Postoperative Hypoxemia In Elderly Patients

Objective:To observe the relationship between diaphragmatic function indexes and hypoxemia after removal of catheter,and to explore the feasibility of diaphragmatic function indexes in predicting hypoxemia after removal of catheter in elderly patients,by measuring diaphragmatic excursion（DE）and diaphragmatic thickening fraction（DTF）with ultrasonography.Methods:From September 2021 to March 2022,a total of 100 patients（male and female,no limitation,ASA II-III,age>65 years old）undergoing laparoscopic upper abdominal surgery under general anesthesia were selected in our hospital.The general clinical data of the patients were recorded.Diaphragmatic ultrasound and blood gas analysis were performed preoperatively（T₀）and 10 min after catheter removal（T₁）.The diaphragmatic excursion,diaphragm thickness and blood gas analysis indexes were recorded.At the same time,the patients were divided into hypoxemia group and non-hypoxemia group according to whether they had hypoxemia 10min after removal of the catheter.The single-factor and multi-factor regression analyses were performed on the indicators with statistical significance between the groups to screen out the risk factors for hypoxemia after removal of the catheter.The receiver operating characteristic（ROC）curve of each risk factor was drawn to predict its ability to assess the occurrence of hypoxemia after extubation.Results:（1）Seventy-nine patients were finally included in this study.There were 17 patients with hypoxemia and 62 patients with non-hypoxemia 10min after catheter removal.Compared with T₀,the diaphragmatic motion amplitude and diaphragmatic thickening rate at T₁in the hypoxemia group and the non-hypoxemia group were lower（P<0.05）.The comparison between the two groups at T₁showed that the diaphragmatic excursion and diaphragmatic thickening rate in the hypoxemia group were decreased more significantly with statistical significance（P<0.001）.（2）The multivariate logistic regression analysis on hypoxemia showed that the quiet breathing diaphragm amplitude of postoperative（OR value=0.44[95%CI:0.35,0.55],P<0.001）,deep breathing diaphragm amplitude of postoperative（OR value=0.90[95%CI:0.74,0.97],P=0.035）,rate of postoperative deep breathing diaphragm thickening（OR value=0.95[95%CI:0.84,0.99],P=0.022）were the protective factors of hypoxemia after extubation.VAS score was a risk factor for hypoxemia after extubation（OR=2.09[95%CI:1.58,4.36],P=0.044）.（3）ROC curve was constructed and it was found that DE of postoperative（quiet breathing and deep breathing）,the deep breathing thickening rate of postoperative diaphragm can predict the occurrence of hypoxemia after catheter removal.Among them,the AUC of the amplitude of postoperative calm diaphragm movement for predicting hypoxemia after catheter removal is 0.96,with the specificity of 94%,and sensitivity of 90%,which is higher than that of other diaphragmatic function indicators.Conclusion:DE of postoperative（quiet breathing and deep breathing）,the deep breathing thickening rate of postoperative diaphragm have high predictive value for hypoxemia in elderly patients after catheter removal.Quiet breathing diaphragmatic excursion of postoperative has the highest predictive value for the occurrence of hypoxemia after extubation,corresponding to the optimal truncation value of 1.55cm,specificity of 94%,sensitivity of 90%.Diaphragmatic ultrasonography can detect diaphragmatic insufficiency in the early stage,which is worthy of clinical application and promotion.