Use of intraoperative transesophageal echocardiography to predict atrial fibrillation after coronary artery bypass grafting.

BACKGROUND: Postoperative atrial fibrillation in coronary artery bypass graft surgery occurs in 10-40% of patients. It is associated with a significant degree of morbidity and results in prolonged lengths of stay in both the intensive care unit and hospital. METHODS: The authors prospectively evaluated patients undergoing coronary artery bypass with detailed transesophageal echocardiography examinations conducted before and after cardiopulmonary bypass to study whether risk factors for atrial fibrillation could be identified. Demographic and surgical parameters were also included in the analysis. Selected variables were subjected to univariate and subsequent multivariate analyses to test for their independent or joint influence on atrial fibrillation. RESULTS: Seventy-nine patients had assessable transesophageal echocardiography examinations. Significant univariate predictors of atrial fibrillation included advanced age (P = 0.002), pre-cardiopulmonary bypass left atrial appendage area (P = 0.04), and post-cardiopulmonary bypass left upper pulmonary vein systole/diastole velocity ratio (P = 0.03). When these three factors were considered together in a multiple logistic regression analysis, left upper pulmonary vein systole/diastole velocity ratio was a significant predictor (P < 0.05), as was the joint effect of age plus pre-cardiopulmonary bypass left atrial appendage area (P = 0.005). The probability of developing atrial fibrillation for the combination of age = 75 yr, post-cardiopulmonary bypass left upper pulmonary vein systole/diastole velocity ratio = 0.5, and left atrial appendage area = 4.0 cm was 0.83 (95% confidence interval, 0.51-0.96). CONCLUSIONS: Early identification of patients at risk for postoperative atrial fibrillation may be feasible using the parameters identified in this study.

Hextend, a physiologically balanced plasma expander for large volume use in major surgery: a randomized phase III clinical trial. Hextend Study Group.

UNLABELLED: Hextend (BioTime, Inc., Berkeley, CA) is a new plasma volume expander containing 6% hetastarch, balanced electrolytes, a lactate buffer, and physiological levels of glucose. In preclinical studies, its use in shock models was associated with an improvement in outcome compared with alternatives, such as albumin or 6% hetastarch in saline. In a prospective, randomized, two-center study (n = 120), we compared the efficacy and safety of Hextend versus 6% hetastarch in saline (HES) for the treatment of hypovolemia during major surgery. Patients at one center had a blood sample drawn at the beginning and the end of surgery for thromboelastographic (TEG) analysis. Hextend was as effective as HES for the treatment of hypovolemia. Patients received an average of 1596 mL of Hextend: 42% received >20 mL/kg up to a total of 5000 mL. No patient received albumin. Hextend-treated patients required less intraoperative calcium (4 vs 220 mg; P < 0.05). In a subset analysis of patients receiving red blood cell transfusions (n = 56; 47%), Hextend-treated patients had a lower mean estimated blood loss (956 mL less; P = 0.02) and were less likely to receive calcium supplementation (P = 0.04). Patients receiving HES demonstrated significant prolongation of time to onset of clot formation (based on TEG) not seen in the Hextend patients (P < 0.05). No Hextend patient experienced a related serious adverse event, and there was no difference in the total number of adverse events between the two groups. The results of this study demonstrate that Hextend, with its novel buffered, balanced electrolyte formulation, is as effective as 6% hetastarch in saline for the treatment of hypovolemia and may be a safe alternative even when used in volumes up to 5 L. IMPLICATIONS: Hextend (BioTime, Inc., Berkeley, CA) is a new plasma volume expander containing 6% hetastarch, balanced electrolytes, a lactate buffer, and a physiological level of glucose. It is as effective as 6% hetastarch in saline for the treatment of hypovolemia but has a more favorable side effects profile in volumes of up to 5 L compared with 6% hetastarch in saline.

Intraoperative transoesophageal echocardiography as an adjuvant to fluoroscopy during endovascular thoracic aortic repair.

OBJECTIVES: To define the utility of intraoperative transeophageal echocardiography (TEE) during endovascular thoracic aortic repair. DESIGN: Retrospective study. MATERIALS: Five patients underwent six transluminal endovascular stent-graft procedures for repair of thoracic aortic disease. METHODS: After induction of anaesthesia, a multiplane or biplane TEE probe was placed to obtain views of the diseased aorta. Both transverse and longitudinal planes of the aortic arch and descending thoracic aortic segments were imaged. The aortic pathology was confirmed by TEE and the proximal and distal extents of the intrathoracic lesion were defined. Doppler and colour-flow imaging was used to identify flow patterns through the aorta before and after stent-graft deployment. RESULTS: Visualisation and confirmation of the aortic pathology by ultrasonography was accomplished in all patients. TEE was able to confirm proper placement of the endograft relative to the aortic lesion after deployment and was able to confirm exclusion of blood flow into the aneurysm sacs. CONCLUSIONS: TEE may facilitate repair by confirming aortic pathology, identifying endograft placement, assessment of the adequacy of aneurysm sack isolation, as well as dynamic intraoperative cardiac assessment.

Neuropsychologic outcome after deep hypothermic circulatory arrest in adults.

INTRODUCTION: Pediatric patients undergoing prolonged periods of deep hypothermic circulatory arrest have been found to experience long-term deficits in cognitive function. However, there is limited information of this type in adult patients who are undergoing deep hypothermic circulatory arrest for thoracic aortic repairs. METHODS: One hundred forty-nine patients undergoing elective cardiac or thoracic aortic operations were evaluated preoperatively; 106 patients were evaluated early in the postoperative period (EARLY), and 77 patients were evaluated late in the postoperative period (LATE) with a battery of neuropsychologic tests. Seventy-three patients had routine cardiac operations without deep hypothermic circulatory arrest, and 76 patients with deep hypothermic circulatory arrest were divided into 2 subgroups: those with 1 to 24 minutes of deep hypothermic circulatory arrest (n = 36 patients) and those with 25 minutes or more of deep hypothermic circulatory arrest (n = 40 patients). The neuropsychologic test battery consisted of 8 tests encompassing 5 domains: attention, processing speed, memory, executive function, and fine motor function. Data were normalized to baseline values, and changes from baseline were analyzed by analysis of covariance, multivariate logistic regression, and survival functions. RESULTS: In all domains, poor performance or inability to be tested EARLY were significant predictors of poor performance LATE (odds ratio, 5.27; P <.01). Deep hypothermic circulatory arrest of 25 minutes or more and advanced age were significant predictors of poor performance LATE for the memory and fine motor domains. Deep hypothermic circulatory arrest of 25 minutes or more (odds ratio, 4. 0; P =.02) was a determinant of prolonged hospital stay (>21 days). CONCLUSION: Deep hypothermic circulatory arrest of 25 minutes or more and advanced age were associated with memory and fine motor deficits and with prolonged hospital stay.

Comparison of the cardiovascular effects of cisatracurium and vecuronium in patients with coronary artery disease.

PURPOSE: Cisatracurium besylate (Nimbex Injection, Glaxo Wellcome Inc., Research Triangle Park, NC) is an intermediate-acting bis-benzylisoquinolinium neuromuscular blocking drug that is one of the stereoisomers of atracurium. At doses < or = 8 x ED95, it caused no clinically important cardiovascular side effects or histamine release in healthy patients. The purpose of the present study was to investigate the haemodynamic effects of high doses of cisatracurium in patients with coronary artery disease. METHODS: One hundred patients undergoing myocardial revascularization participated in a pilot study (seven patients) and a double-blinded, randomized, controlled trial comparing the haemodynamic effects of cisatracurium with vecuronium at three centres. The patients were anaesthetized using oxygen 100%, with etomidate, fentanyl and a benzodiazepine, and tracheal intubation was facilitated using succinylcholine. After baseline haemodynamic measurements, the study drug was administered over 5-10 sec according to group assignment: Group A (pilot) cisatracurium, 0.20 mg.kg-1 (4 x ED95), (n = 7); Group B-cisatracurium, 0.30 mg.kg-1 (6 x ED95), (n x ED95), (n = 31); Group C-vecuronium, 0.30 mg.kg-1 (6 x ED95), (n = 31); Group D cisatracurium, 0.40 mg.kg-1 (8 x ED95), (n = 21); Group E-vecuronium, 0.30 mg.kg-1 (6 x ED95), (n = 10). The haemodynamic measurements were repeated at 2, 5, and 10 min after cisatracurium or vecuronium. RESULTS: Two patients in Group D had > 20% decreases in MAP, but only one required therapy for hypotension. The haemodynamic changes from pre- to post-injection in the cisatracurium patients were minimal and similar to patients receiving vecuronium. CONCLUSIONS: In patients with coronary artery disease, rapid cisatracurium (4-8 x ED95) boluses and vecuronium (6 x ED95) result in minor, clinically insignificant haemodynamic side effects.

Intraoperative transesophageal echocardiography during noncardiac surgery.

OBJECTIVE: To investigate the use and impact of transesophageal echocardiography (TEE) during noncardiac surgery. DESIGN: Retrospective study. SETTING: A university teaching hospital. PARTICIPANTS AND INTERVENTIONS: The medical records and the videotapes of 123 intraoperative TEE examinations were reviewed. MEASUREMENTS AND MAIN RESULTS: TEE was used for non-consultative indications in 68 patients and in consultation in 55 patients. Information that would not have been detected intraoperatively by other means included intracardiac defects, valvular and aortic pathology, the presence or absence of ventricular dysfunction or intracardiac thrombi, and embolization during surgery. Findings during the initial TEE examination and the TEE evaluation of intraoperative events resulted in a major impact on patient management in 15% of patients. The majority of patients in whom TEE had any impact (the sum of major, minor, and limited impact groups) were classified as American Society of Anesthesiologists (ASA) class 3 or 4. Patients in whom TEE had any impact were significantly older than patients in whom TEE had no impact (66.5 +/- 13.4 years v 58.1 +/- 16.2 years; p < 0.05). No patient experienced a complication related to intraoperative TEE. CONCLUSION: It appears that TEE in patients undergoing noncardiac surgery is efficacious in rapidly disclosing new findings and information during periods of hemodynamic instability. It may have a significant impact on intraoperative patient management and may be beneficial in patients older than 66 years of age.

An algorithm for assessing intraoperative mean arterial pressure lability.

BACKGROUND: Intraoperative blood pressure lability may be related to risk factors, hypovolemia, light anesthesia, and morbid outcomes, but the measurements of lability in previous studies have been limited by imprecise and infrequent data collection methods. Computerized intraoperative data acquisition systems have provided an opportunity to readdress the issue of intraoperative blood pressure lability with more abundant and precise data. This study sought to derive and validate an algorithm (expert system) to measure mean arterial pressure (MAP) lability. METHODS: Two hundred thirty-nine computerized anesthesis records were reviewed retrospectively. Three anesthesiologists separately rated MAP as very stable, average, or very labile. The parameters of a computer algorithm that measured the change of median MAP between consecutive 2-min epochs were optimized to achieve the best possible agreement among the anesthesiologists. The algorithm was then validated on 229 additional anesthesia records. RESULTS: The proportion of consecutive 2-min epochs in which the absolute value of the fractional change of median MAP exceeded 0.06 (i.e., 6%) correlated strongly with the anesthesiologists' ratings (r = 0.78; P < 0.0001). The optimal sensitivity and specificity of the algorithm for detecting MAP lability were 98% and 59%, respectively. CONCLUSIONS: One potential application of expert systems to anesthesia practice is a "smart alarm" to detect blood pressure lability. It may also provide a better tool to assess the relation between lability and outcome than has been available previously.

Intraoperative transesophageal echocardiography during liver transplantation.

OBJECTIVE: To investigate the safety, value, and impact of transesophageal echocardiography during liver transplantation. DESIGN: Retrospective. SETTING: University teaching hospital. PARTICIPANTS AND INTERVENTIONS: The medical records of 346 patients and the videotapes of 100 intraoperative transesophageal echocardiography examinations were reviewed. MEASUREMENTS AND MAIN RESULTS: Transesophageal echocardiography was indicated for intraoperative monitoring in 62 patients, 41 of whom had pertinent findings, and for diagnostic purposes in 38 patients, 14 of whom had the expected diagnosis verified. Thirty-one patients had no intraoperative findings. Information that would not have been detected intraoperatively by other means included intracardiac defects, the potential for transpulmonary air passage, valvular regurgitation, the presence or absence of ventricular dysfunction, and embolization occurring at allograft reperfusion. Unanticipated findings during the initial transesophageal echocardiography examination as well as evaluation of intraoperative events resulted in a major impact on patient management in 11% of patients. Preoperatively, 64 patients had a prothrombin time greater than 14 seconds; 56 had a platelet count less than 100,000/mm3; and 23 had esophageal varices, 7 of whom had not had variceal sclerotherapy. Two patients had a complication possibly caused by transesophageal echocardiography (sinus bradycardia and upper gastrointestinal bleeding). No patient experienced documented variceal hemorrhage, esophageal or gastric perforation, and/or oropharyngeal trauma. CONCLUSIONS: It appears that transesophageal echocardiography can be performed safely in patients undergoing liver transplantation, is efficacious in rapidly disclosing new information and monitoring during periods of hemodynamic instability, and may have a significant impact on intraoperative patient management during liver transplantation.

Validation of a test of competence in transesophageal echocardiography.

OBJECTIVE: A test was developed that is based on intraoperative findings to evaluate knowledge of intraoperative echocardiography. This study examines the performance of attending anesthesiologists and residents at various levels of training in order to validate the test's ability to measure physician competence in intraoperative echocardiographic diagnosis. DESIGN: This study was a prospective evaluation of a test of competence in transesophageal echocardiography. SETTING: Two university medical centers. PARTICIPANTS: Volunteer anesthesia faculty and residents. INTERVENTIONS: The participants took an echocardiographic examination that consisted of 34 "K"-type multiple-choice questions and a 45-second video-loop sequence for each question. The video sequences were chosen for their high quality and unambiguous representation of both normal and pathologic images obtained by transverse transesophageal echocardiographic imaging. The questions were written by experienced echocardiographers. The test was administered to 25 individuals at two academic institutions: 11 residents with minimal transesophageal echocardiography exposure and 14 faculty who were relatively experienced with transesophageal echocardiography. All of the residents repeated the examination at the end of their third clinical anesthesia year, which included transesophageal echocardiography training. The differences between the groups' scores were analyzed using the Kruskal-Wallis test and Wilcoxon's rank-sum test. To correct for the multiple comparisons, p < 0.025 was deemed significant. MEASUREMENTS AND MAIN RESULTS. Before their transesophageal echocardiography training, the residents scored significantly lower than the faculty (p < 0.002). After 1 year of training, their scores significantly increased (p = 0.021), and their scores were not significantly different from the faculty level (p = 0.052). CONCLUSIONS: Test performance differed according to level of experience. This suggests that the test is a valid measure of intraoperative transesophageal echocardiography competence.

Predictors of pulse oximetry data failure.

BACKGROUND: Pulse oximeters have been reported to fail to record data in 1.12-2.50% of cases in which anesthesia records were handwritten. There is reason to believe that these may be underestimates. Computerized anesthesia records may provide insight into the true incidence of pulse oximetry data failures and factors that are associated with such failures. METHODS: The current study reviewed case files of 9,203 computerized anesthesia records. Pulse oximetry data failure was defined as the presence of at least one continuous gap in data > or = 10 min in duration in a case. A multivariate logistic regression model was used to identify predictors of pulse oximetry data failure, and a modified case-control method was used to determine whether extremes of blood pressure and hypothermia during the procedure were associated with pulse oximetry data failure. RESULTS: The overall incidence of cases that had at least one continuous gap of > or = 10 min in pulse oximetry data was 9.18%. The independent preoperative predictors of pulse oximetry data failure were ASA physical status 3,4, or 5 and orthopedic, vascular, and cardiac surgery. Intraoperative hypothermia, hypotension, hypertension, and duration of procedure were also independent risk factors for pulse oximetry data failure. CONCLUSIONS: Pulse oximetry data failure rates based on review of computerized records were markedly greater than those previously reported. Physical status, type of surgery, and intraoperative variables were risk factors for pulse oximetry data failure. Regulations and expectations regarding pulse oximetry monitoring should reflect the limitations of the technology.

High reproducibility in the interpretation of intraoperative transesophageal echocardiographic evaluation of aortic atheromatous disease.

Intraoperative decisions are often based on interpretation of results from transesophageal echocardiography (TEE). One such area is the intraoperative evaluation of atheromatous disease of the thoracic aorta and subsequent classification or grading. These grading schemes are predictive of stroke after cardiac surgery. Since intraoperative strategies may be modified based on this TEE aortic atheroma grading, assessment of the interobserver variability of TEE findings between observers is essential. Forty TEE videotape segments imaging three portions of the thoracic aorta (ascending, arch, descending) were selected from 189 reports of a larger cohort. Three independent, blinded observers, experienced in TEE, evaluated these examinations for atheroma severity. If a TEE segment had insufficient data, "uninterpretable" was recorded. Weighted kappa coefficients of agreement were calculated on the three data sets. Mean weighted kappa coefficients for the three observers A, B, and C were 0.69, 0.74, and 0.72, for the ascending, arch, and descending aorta segments, respectively, representing excellent agreement. We have demonstrated uniformly high agreement for interpretation of TEE, which indicates the excellent reproducibility of TEE grading and stratification of aortic atheroma. Reproducibility within and across specialties and institutions is essential for widespread application of TEE for evaluation of the thoracic aorta.