Evaluation of diaphragmatic dysfunction after surgical treatment of type A aortic dissection by ultrasound: incidence, risk factors and influence on outcomes

Abstract

Objective To study the incidence, possible risk factors, and influence on patient outcomes of diaphragmatic dysfunction in patients after surgical treatment of type A aortic dissection using ultrasound. Methods Patients who received replacement of hemiarch or total arch with concomitant procedures concerning aortic pathology, and an elephant trunk procedure for the descending aorta were prospectively enrolled in this study from February to May 2017. After surgery, they were transferred to the cardiac surgical intensive care unit. They were divided into two groups based on diaphragmatic excursion: diaphragmatic dysfunction (DD) group and diaphragmatic function normal (DN) grouBilateral diaphragmatic excursions were evaluated using ultrasound during spontaneous breathing trial by T-tube. The differences in demographic characteristics, operation-related variables and outcomes were compared between the two groups. Results A total of 42 patients were enrolled in this study, and 32 of them suffered from diaphragmatic dysfunctions. Compared with DN group, the excursion of the influenced diaphragm in DD group was significantly reduced[(0.450±0.331)cm vs. (1.801±0.616)cm, P<0.01], while the excursion of the non-influenced diaphragm was not reduced[(2.013±0.655)cm vs. (1.801±0.616)cm, P=0.254]. Diaphragmatic thickness was comparable [(0.184±0.028)cm vs. (0.189±0.028)cm, P=0.559 ] between the two groups while thickening fraction was significantly reduced in DD group[(4.67%±3.63)% vs. (23.58%±10.69)%, P<0.01]. Meanwhile, respiratory rate was significantly higher in DD group as compared to DN group [(24.13±4.98)times/min vs. (20.50±3.17)times/min, P=0.037]. Patients in DD group showed longer cross-clamp duration[(121.78±27.75)min vs. (93.10±18.84)min, P=0.004] and longer cardiopulmonary bypass duration [(208.09±32.78)min vs. (182.70±24.38)min, P=0.03] than patients in DN grouFurthermore, binary logistic analysis indicated that longer cross-clamp duration was the potential risk factor for diaphragmatic dysfunction after type A aortic dissection surgery. Mechanical ventilation duration was longer in DD group than in DN group (88 h vs. 37 h, P=0.194) but without statistical significance. The usage of noninvasive ventilation was significantly increased in DD group as compared to DN group (46.88% vs. 10%, P=0.036). Other outcomes such as post-operative complications, mortality, ICU length of stay were comparable between the two groups. Conclusions Diaphragmatic dysfunction was very common after surgical treatment of type A aortic dissection. Longer duration of cross-clamp was considered as a potential risk factor of diaphragmatic dysfunction. A sequential management of noninvasive ventilation after extubation was feasible for diaphragmatic dysfunction after surgical treatment of type A aortic dissection. Key words: Diaphragm; Ultrasound; Type A aortic dissection