Research On The Effect Of Arterial Blood Lactic Acid On Delayed Weaning In Patients Undergoing Mechanical Ventilation After Off-pump Coronary Artery Bypass Grafting

Objective1 To investigate the correlation between arterial blood lactate level and serum creatine kinase isoenzymes and cardiac troponin T levels at 4 hours after off-pump coronary artery bypass grafting and delayed weaning of mechanical ventilationpatients after off-pump coronary artery bypass grafting.2 To explore the change trend of 24-hour arterial blood lactate in patients with delayed weaning after off-pump coronary artery bypass grafting,and to provide a reference for future clinical medical workers to wean patients with mechanicalventilation after off-pump coronary artery bypass grafting.MethodA longitudinal observation study was conducted to investigate 359 patients who underwent off-pump coronary artery bypass grafting in Tianjin Chest Hospital from October 2016 to September 2018.Among them,77 were delayed weaning patients(observation group)and 282 were not delayed weaning patients(control group).Collect and sort out the clinical and laboratory examination results of patients.The clinical data mainly included age,sex,length of operation,number of arterial bypass grafts,history of smoking and alcohol,diagnosis results,past history,and intraoperative and postoperative volume.The results of laboratory examination were the creatine kinase isoenzymes and cardiac troponin T test values on the 24 hours before and 4 hours after the operation,and the arterial blood gas analysis values on the day before and 1 hour,4 hours after the operation,and before or after the spontaneous breathing exercise.The data were analyzed by SPSS20.0 statistical software.Logistic regression analysis,?~2 test and t test,Ztest were used to analyze the risk factors of delayed weaning in patients with mechanical ventilation after off-pump coronary artery bypass grafting and the change trend of arterial blood lactate in patients with mechanical ventilation delayed weaning after off-pump coronary artery bypass grafting.Results1 Comparison of 24-hour arterial blood lactate,creatine kinase isoenzyme and cardiac troponin T test before operation between the observation group and the control group after off-pump coronary artery bypass grafting:24-hour arterial blood lactate(t=1.407,P=0.163),24-hour preoperative creatine kinase isoenzyme(t=-1.026,P=0.308),and preoperative cardiac troponin T(t=0.243,P=0.809)has no significant difference.2 Comparisons of arterial blood lactate values in patients with mechanical ventilation after off-pump coronary artery bypass grafting between the observation group and the control group at 1 hour,4 hours and after off-line/spontaneous breathing test:arterial blood lactate values at 1 hour after operation(t=2.285,P=0.024),arterial blood lactate values at 4 hours after operation(t=3.133,P=0.002),and arterial blood lactate values before and after off-line/spontaneous breathing test(t=6.025,P<0.001)has significant difference.3 Trend analysis of lactic acid in arterial blood of patients with mechanical ventilation after off-pump coronary artery bypass grafting in observation group and control group 1 hour,4 hours after operation,before weaning/after spontaneous breathing test.The results showed that the average lactic acid in arterial blood of observation group was>2.0mmol/L after operation,suggesting that the patients in observation group were in the state of hyperlactic acid after operation,and the patients in observation group were in the state of lactic acid in arterial blood The value of lactic acid in the arterial blood of the patients in the control group increased first and then decreased to the normal level.4 Comparisons of creatine kinase isoenzymes and cardiac troponin T values at 4hours after off-pump coronary artery bypass grafting between the observation group and the control group:the differences in creatine kinase isoenzymes at 4 hours after operation(t=3.636,P<0.001)and cardiac troponin T at 4 hours after operation(t=3.223,P=0.002)have statistical significance.5 The value of lactic acid in arterial blood after off-pump coronary artery bypass grafting is of reference value in judging whether the patients with mechanical ventilation after off-pump coronary artery bypass grafting can be weaning normally,especially the value of lactic acid in arterial blood before weaning/after spontaneous breathing test in off-pump coronary artery bypass grafting patients.The risk of delayed weaning of mechanical ventilation patients after off-pump coronary artery bypass grafting is more than 90%when the lactate level of arterial blood exceeds4.552mmol/L before weaning/after spontaneous breathing test.6 Compared with the control group,the difference of the duration of mechanical ventilation after off-pump coronary artery bypass grafting in the observation group(t=11.904,P=0.001)was statistically significant.Long operation time in patients undergoing off-pump coronary artery bypass grafting is a risk factor for delayed weaning in patients undergoing mechanical ventilation after off-pump coronary artery bypass grafting.When the duration of surgery was longer than 4.90 hours,the risk of delayed weaning of mechanical ventilation patients after off-pump coronary artery bypass grafting was more than 90%.Conclusion1 The risk factors of delayed weaning in patients undergoing off-pump coronary artery bypass grafting are 3 times higher creatine kinase isozyme value than normal value high limit at 4 hours after operation,cardiac troponin T value greater than1.0ng/mL,and high arterial blood lactate value after operation.2 The lactate level in arterial blood of patients with delayed weaning after off-pump coronary artery bypass grafting is increasing gradually.The main reasons for the high lactate level in arterial blood after off-pump coronary artery bypass grafting are insufficient tissue perfusion and ischemia and hypoxia after off-pump coronary artery bypass grafting.3 The value of lactic acid in arterial blood after off-pump coronary artery bypass grafting can be used as a reference for judging whether the patients with mechanical ventilation after off-pump coronary artery bypass grafting can be weaning normally,especially the value of lactic acid in arterial blood before weaning/after spontaneous breathing test in off-pump coronary artery bypass grafting patients.4 Long operation time in patients undergoing off-pump coronary artery bypass grafting is a risk factor for delayed weaning in patients undergoing mechanical ventilation after off-pump coronary artery bypass grafting.