主动脉夹层动脉瘤术后低氧血症的危险因素

Risk factors for hypoxemia after aortic dissection procedures

目的探讨主动脉夹层动脉瘤术后低氧血症发生的危险因素。方法2005年8月至2008年5月，175例夹层动脉瘤病人行手术治疗，根据到达监护室6h后动脉血氧分压（mmHg）／吸入氧浓度（％）（PaO2／FiO2）分为低氧血症组（PaO2／FiO2〈200）和非低氧血症组（PaO2／FiO2≥200）。评估及比较两组的年龄、性别、体重指数、有无吸烟史、症状出现至手术时间、是否行急诊手术、手术方式、体外循环时间、主动脉阻断时间、深低温停循环时间、最低直肠温度、术后24h内引流量和输血量等因素以及ICU停留时间、呼吸机辅助时间、住院时间和院内病死率。结果主动脉夹层动脉瘤术后低氧血症发生率为28％（49／175例）。低氧血症组平均呼吸机辅助（83．09±123．71）h，非低氧血症组（29．50±29．07）h（P=0．017）；低氧血症组平均ICU停留（7．46±5．16）d，非低氧血症组（4．25±6．62）d（P=0．007）；低氧血症组平均住院（24．45±17．84）d，非低氧血症组（19．19±10．18）d（P=0．041）。术前、术中及术后单因素分析中有统计学意义的因素包括体重指数、吸烟史、发病至手术时间、急诊手术、手术方式、深低温停循环和术后24h内输血量。多因素回归分析显示，深低温停循环、输血量〉5U和体重指数〉25kg／m。为有意义的独立预测因素。结论低氧血症是主动脉夹层动脉瘤术后常见的并发症，术后低氧血症的危险因素包括体重指数、吸烟史、急诊手术、深低温停循环和术后24h输血量。加强围术期处那是防治夹层主动脉瘤术后低氧血症的有效方法。

Objective Aortic dissection is a life-threatening disease associated with high morbidity and mortality. As a common complication for aortic dissection surgery, hypoxemia may increase the mortality and prolong the duration of mechanical ventilation and ICU stay. We investigate the risk factors associated with hypoxemia after aortic dissection procedures and try to find strategies for its prevention and management. Methods From August 2005 to May 2008, 175 patients underwent operations for aortic dissection （ 133 men and 42 women, age 17 to 76, with an average age of 47.66）. Among these patients, 116 patients received a diagnosis of De Bakey type I, 16 patients received a diagnosis of type II and 43 patients received a diagnosis of type III. The operations were performed from 3 hours to 10 years after the onset of symptoms. Procedures performed were ascending aortic replacement in 77 patients, ascending aortic replacement combined with aortic valve replacement in 3 patients, Bentall operation in 44 patients, total arch replacement in 53 patients, hemiarch replacement in 45 patients, descending aortic replacement in 48 patients and descending aortic stenting in 42 patients. Postoperative hypoxemia was defined as the ratio of arterial partial oxygen to inspired oxygen fraction （PaO2/FiO2） more than 200 about 6 hours after a patient was admitted to an intensive care unit （ICU）. Comparisons were performed between hypoxemia group and non-hypoxemia group in age, gender, body mass index（ BMI）, smoking history, time from onset to operation, ＂door-to-operation＂ time, duration of cardiopulmonary bypass （CPB） and deep hypothermic circulatory arrest （DHCA）, lowest rectal temperature, requirement for red blood cell transfusion and the amount of drainage, hours for mechanical ventilation and days for ICU stay, and in-hospital mortality. Results The incidence of postoperative hypoxemia was 28% （49/175）. Postoperative hypoxemia was significantly associated with the overall in-hospital mortality and hospital stay （ P 〈 0.01, P = 0. 041, respectively）. The duration of mechanical venti- lation was increased significantly （83.09 ± 123.71 ） hours in the hypoxemia group, as compared with that （29.50 ± 29.07 ） hours in the non-hypoxemia group （P =0. 017）, as was the days of ICU stay （7.46 ±5.16 in the hypoxemia group and 4.25 ± 6.62 in the non-hypoxemia group ; P = 0. 007 ）. Univariate analysis to pre-and postoperative characteristics in patients who underwent surgical procedures for aortic diseases showed that BMI, smoking history, time from onset to operation, emergency surgery, DHCA, and red blood cell transfusion in 24 hours after operation were associated with hypoxemia significantly. Logistic regression analysis showed that BMI 〉 25 kg/m^2 , DHCA and blood transfusion 〉 5U were significantly independent predictors for hypoxemia. Conclusion Postoperative hypoxemia is a common complication for aortic dissection operation. BMI, smoking history, emergency surgery, DHCA, and red blood cell transfusion in 24 hours after operation were significant risk factors. Intensified perioperative management can improve the clinical outcomes of patients with risk factors.