Reduction Of The PaO2/FiO2Ratio In Acute Aortic Dissection And The Effect Of Lung Recruitment

Objective:The incidence of acute aortic dissection is often accompanied by respiratory insufficiency. The article dedicated to screening risk factors of hypoxemia in patients with acute aortic dissection.Methods:A retrospective analysis of patients with acute aortic dissection, from July2009to January2011in Fuwai Hospital, including gender, age, body mass index, Aortic dissection type, associating with hypertension, coronary heart disease, diabetes, chronic obstructive pulmonary disease (COPD), as well as the laboratory examination:count of white blood cell, hemoglobin, platelet count, serum creatinine, C reactive protein (CRP), D-dimer, blood glucose, PT and etc. Hypoxemia is defined as the oxygenation index less than150(PaO2/FiO2<150), and oxygenation index of less than100(PaO2/FiO2<100) as severe hypoxemia. Univariate analysis and multivariate Logistic regression were used to analyze the association between "general condition" of patients and laboratory variables and hypoxemia.Results:Two hundred and forty-seven patients were enrolled in this study, including145cases (58.7%)Stanford type A aortic dissection and102cases (41.3%) of type B. In these selected patients,197cases were male (79.8%) and50cases were female (20.2%), whose average age was48.5±10.1years old, while male and female patients with an average age of no difference (47.9±9.9years old vs.50.8±10.7years of age, P>0.05). The mean oxygenation index was160.0±42.3, of which113cases (45.7%) patients with hypoxemia, oxygenation index of hypoxemia group was127.3±15.9, oxygenation index of non-hypoxic group the was187.9±37.5(P<0.05). There are six cases of severe hypoxemia, and the incidence rate is2.4%. Univariate analysis found risk factors for hypoxemia include:body mass index BMI (26.13±2.48kg/m2vs24.14±2.62kg/m2, P<0.05); history of smoking (45vs30cases, P<0.05); white blood cell count (12.31±3.75×109/L vs9.59±3.68×109/L, P<0.05); platelet count (176.18±65.04×109/L vs208.80±76.83×109/L, P<0.05) C-reactive protein (18.31vs15.74mg/L,P<0.05); D-dimer (3.92vs2.07μg/ml, P<0.05); serum creatinine (99.58±42.41μmol/L vs88.28 ±30.09μmol/L,<0.05); blood glucose (7.58±2.07mmol/L vs6.87±1.58mmol/L, P<0.05)。 Multivariate linear regression of related factors for hypoxemia include:C reactive protein concentration (B:-7.707,95%CI:-14.581～-0.834, P=0.029). Logistic regression analysis of independent risk factors for hypoxemia include:body mass index (OR:1.381,95%CI:1.226-1.556); history of smoking (OR:2.475,95%CI:1.358-4.509)。Conclusion:Hypoxemia has high incidence in patients with acute aortic dissection. Abnormal of systemic inflammation may be associated with impaired lung function. Assessment of the clinical risk factors can guide treatment and reducing the occurrence of related complications. Objective:To investigate the clinical effect of lung recruitment maneuver on postoperative hypoxemia of deep hypothermia circulatory arrest (DHCA) aortic surgery, and to evaluate the safety of this treatment.Methods:From November2010to November2011, forty patients undergoing DHCA aortic surgery with severe postoperative hypoxemia (PaO2/FiO2<100) were randomly allocated into two groups:control group (n=20):conventional mechanical ventilation with positive end expiratory pressure (PEEP); experimental group (n=20):Lung recruitment maneuvers (RM). The arterial blood gas, the duration of ventilation and haemodynamics variables were compared between these groups.Results:The mean age of these forty patients was47.2±25.0years, and there was no difference between the control group and the experimental group (48.3±8.4years vs46.0±9.7years, P=0.725). Thirty cases were male, fifteen in each group, accounting for75%. The body mass index (BMI) matched between two groups (24.9±3.7kg/m2vs25.2±3.0kg/m2, P=0.419). There were nine cases and ten cases with a history of smoking respectively (45%vs50%, P=0.752). The oxygenation index of the control group and the RM group showed no significant difference before treatment (PaO2/FiO2:94.7±2.8vs94.0±2.9, P=0.486), and the oxygenation index of RM group was improved significantly (PaO2/FiO2:94.0±2.9vs180.4±31.8, P<0.001). PaCO2and tidal volume (VT) had no significant changes after treatment. In both groups the haemodynamics were stable by adjusting the vasoactive drugs. The mechanical ventilation time in RM group was shorter than control group, but the difference was not signifcant (25.4±16.4vs21.8±12.6h, P=0.441).Conclusion:Lung recruitment maneuver is an effective and safe method to improve the oxygenation of hypoxemia patients after DHCA aortic surgery.