A Systemic Research Of Neurological Complications In Patients After Type A Aortic Dissection Surgery

BACKGROUNAortic dissection(AD)is one of the cardiac diseases with the highest mortality,especially Stanford type A,which is characterized by urgent onset,rapid progress,and poor outcome.The mortality rate of AD within 48h increases by 1%per an hour,and till 3 months later,the mortality rate can reach 90%.Several different classification systems have been used to describe aortic dissections.The Stanford system is used more commonly now,as it is more attuned to the management of the patient.The Stanford classification is divided into two groups,A and B.Type A refers to AD which involves the ascending aorta and/or aortic arch,and possibly the descending aorta.The tear can originate in the ascending aorta,the aortic arch,or more rarely,in the descending aorta.It includes DeBakey types ? and ?.Type B involves the descending aorta or the arch(distal to the left subclavian artery),without the involvement of the ascending aorta.It includes DeBakey type ?.Surgery is the most effective treatment.Although recent advances in the understanding and management of various aspects of these complex surgical procedures are remarkable,many potential complications still exist after the operation.Neurological complication is one of the serious postoperative complications for type A aortic dissection.It can badly influence patient's prognosis,such as prolonged hospitalization,increased medical cost or higher mortality rate,and lead to the decrease of quality of daily life.According to the duration of nurological complication,it can be divided into temporary neurological dysfunction(TND)and permanent neurological dysfunction(PND).TND was recognized as a functional manifestation of transient brain injury,inlucding transient ischemic attach,confusion,depression and delirium.The presence of neurological dysfunction at the time of discharge is defined as PND,whether focal or global injury.According to clinical manifestation,neurological complication can also be divided into different groups,such as cerebral ischemia,spinal ischemia,cerebral bleeding,ischemic neuropathy,hypoxic encephalopathy,nerve compression and delirium.The incidence of postoperative neurological complication for type A aortic dissection ranges from 17%to 40%.Delirium is one of the neurologic complications after type A aortic dissection surgery.It is defined as an acute and fluctuating state of disturbances in attention,awareness,and cognition.Delirium can occur in any patient during the early postoperative period.However,recent guidelines do not recommend any drugs to prevent or treat delirium because it is unclear whether pharmacological interventions are effective.Instead,studies indicate that the identification and modification of risk factors is the best intervention for delirium.Despite an increasing interest in delirium,there have been no specific studies on the risk factors of postoperative delirium after aortic dissection surgery.The goal of our study was to explore the postoperative neurological complications of type A aortic dissection,and the risk factors for postoperative delirium(POD)furthermore.This study can be divided into two parts.Part one Study of postoperative neurological complications for type A aortic dissectionOBJECTIVETo study the postoperative neurological complications for type A aortic dissection and its relationship with postoperative mortality.METHODS163 consecutive type A aortic dissection patients after Sun's procedure,with or without aortic valve replacement,were studied retrospectively from October 1,2014 to October 1,2016 in our cardiac surgical intensive care unit.The preoperative treatment,anesthetic regiment and intraoperative brain protection strategy were standard among them.All the patients were eligible for inclusion in the study unless the following criteria applied:(1)patients who had preoperative diagnosed mental disease;(2)patients died during surgery;(3)cases with incomplete data collection.Kept patients' postoperative consciouness status under strict surveillance and determined the diagnosis of pneurological complications according to the focal neurological signs,imageological examination and the suggestion of consultation from professional neurologist.Pay attention to patients' clinical manifestation,such as hemiplegia,paraplegia,monoplegia,sensory disturbance,visual or auditory dysfunction or nerve compression symptom,and treated it properly.Next,we divided the enrolled patients into two groups according to the presence of neurological complicatons or non,and compared the postoperative mortality between them using?2 test.RESULTSIn our research,163 patients were admitted into the study,and 70 of these patients were diagnosed with postoperative complications,for an incidence of 43.2%(70/163).The mean age of 70 patients was 58-year-old and the ratio between male and female was 1.4:1.The peak age for male was from 50 to 60,while for female was from 60-70.14 of the 70 patients had preoperative neurological complications and evolved with additional manifestation after surgery.Neurological complications were divided into different groups and analyzed in detail,including 16(23%)cerebral ischemia,1(1%)spinal ischemia,1(1%)cerebral bleeding,4(6%)ischemic neuropathy,6(9%)hypoxic encephalopathy,1(1%)nerve compression,36(52%)delirium and 5(7%)combinations.Among the 70 patients,5 died in the end with the mortality rate of 7.1%,while the mortality rate of other 93 patients was 7.5%(7/93).There was no statistical difference of postoperative mortality rate between this two groups with P vale of 0.478.CONCLUSIONSThe incidence of postoperative neurological complications for type A aortic dissection is high,because of its complicated pathophysiology and difficult surgery procedure,and is associated with many factors.It can influence patients' prognosis seriously.We should keep alert on the possibility of postoperative neurological complications in order to reduce its incidence and harm in clinical practice.Part two Risk factors of postoperative delirium for type A aortic dissectionOBJECTIVETo study the related risk factors for postoperative delirium of type A aortic dissection patients.METHODS1.Delirium AssessmentAll the 163 patients enrolled above were assessed with CAM-ICU to determine their mental status,with delirium or not.The CAM-ICU method was used every 4 hours postoperatively until they left our intensive care unit and was divided into two steps.The first step was to assess patient's consciousness by the Richmond Agitation-Sedation Scale(RASS).If patient's RASS score was-4 or-5,the patient was ineligible for CAM-ICU assessment.In this case,the sedation medication dose was adjusted if the patient was sedated,and then assessment was performed later.If the patient's RASS score was from-3 to +4,then we moved to the second step.The second step was to assess delirium with CAM-ICU in a standard manner.The criteria of CAM-ICU include 4 features:(1)an acute onset of changes or fluctuations in the course of mental status in the last 24 hours,(2)inattention,(3)disorganized thinking,and(4)an altered level of consciousness.Delirium was diagnosed if feature(1)and(2)plus either feature(3)or(4)existed.Assessment of delirium was performed by a nurse trained to use CAM-ICU and confirmed by ICU physicians who were involved in the daily care of the patient.2.Data CollectionWe selected 29 potential risk factors for postoperative delirium with type A aortic dissection retrospectively.The variables were divided into the following 3 categories:preoperative,intraoperative,and postoperative.There were 10 preoperative risk factors including demographic date(age,sex,or education level),smoking(tobacoo use 3 months before operation),alcohol use(3 months before operation),barrier of hearing or language,hypertension(?140/90mmHg),diabetes mellitus,cerebrovascular disease history,and renal insufficiency(elevated serum creatinine concentration,?97umol/L).There were 6 intraoperative risk factors including surgery type(with or without aortic valve replacement),surgery duration,cardiopulmonary bypass(CPB)duration,aortic cross-clamping duration,moderate hypothermic circulation arrest(MHAC)time(25 ? with unilateral antegrade selective cerebral perfusion 5ml/min),and blood transfusion>1L.There were 13 postoperative variables in this research.They were postoperative drainage volume within 24 hours(>1L or not),type and duration of inotropic medication,ICU stay,intubation time,analgesia use,MAP,hypoxia(PaO2<60mmHg),temperature,hemoglobin,electrolyte disturbance(metabolic disturbance of serum sodium,potassium,calcium and magnesium),cardiac arrhythmia(sinus arrhythmia,atrial arrhythmia,artioventricular arrhythmia,ventricular arrhythmia and cardiac conduction block),and elevated creatinine(?97umol/L).3.Statistical analysisContinuous variables are shown as means and SD or medians and interquartile ranges;categorical data are presented as proportions.For comparisons of continuous variables,t test or Wilcoxon test was used depending on the distribution of data.The categorical data were compared by the?2 test or the Fisher exact test depending on the size of groups.To examine the impact of various factors on the incidence of delirium,we used univariate stepwise logistic regression analysis for factors with a P value<0.2.A P value<0.05 was considered statistically significant for multivariate regression.RESULTS163 patients were admitted into the study,and 39 of these patients were diagnosed with delirium,for an incidence of delirium in our research of 23.9%.The results of univariate analysis revealed that 17 risk factors were statistically different between delirium and non-delirium groups,inclueding hypertension,diabetes mellitus,cerebrovascular disease history,preoperative renal insufficiency,surgery duration,CPB duration,intraoperative blood transfusion>1L,postoperative drainage volume within 24 hours>1L,type of inotropic medication,ICU stay,intubation time,analgesia use,postoperative hypoxia,temperature,electrolyte disturbance,cardiac arrhythmia and postoperative elevated creatinine.Significant variables with a P value<0.2 were studied using multivariate stepwise logistic regression analysis.The best regression model contained 5 factors:cerebrovascular disease history,surgery duration,CPB duration,postoperative hypoxia and intubation time.Of the factors studied,the relationship between surgery duration and postoperative delirium was the most remarkable.CONCLUSIONSDelirium is a complex phenomenon and may cause a poor clinical outcome for aortic dissection patients.Unfortunately,there are no effective treatment approaches.In this study we found that the incidence of postoperative delirium for patients with aortic dissection was very high,and it was independently associated with five factors,including cerebrovascular disease history,CPB duration,intubation time,hypoxia and especially surgery duration.This study will help increase our practical awareness of delirium and encourage active monitoring for the development of delirium using CAM-ICU.Furthermore,we can reduce the incidence of delirium or improve its prognosis by modifying the significant factors described here.