John E. Ellis

High Body Mass Index Does Not Predict Mortality in Older People: Analysis of the Longitudinal Study of Aging

OBJECTIVE: To determine the excess mortality associated with obesity (defined by body mass index (BMI)) in older people, with and without adjustment for other risk factors associated with mortality and for demographic factors.

Relative effectiveness of four preoperative tests for predicting adverse cardiac outcomes after vascular surgery : a meta-analysis

Various noninvasive tests have been proposed to stratify perioperative cardiovascular risk, including dipyridamole thallium scintigraphy (DTS), ejection fraction estimation by radionuclide ventriculography (RNV), ischemia monitoring by ambulatory electrocardiography (AECG), and dobutamine stress echocardiography (DSE). Which of these tests is most effective for predicting adverse perioperative cardiac outcome? To answer this question, and also to stimulate future studies, we evaluated 56 studies examining one or more of the four tests. We conducted meta-analysis on 20 studies that met the inclusion criteria. Outcome measures evaluated were cardiac death or myocardial infarction occurring during hospital stay or within 1 mo after surgery. Relative risk (RR), which is the probability of adverse cardiac outcome when the test is positive divided by the probability of adverse outcome when the test is negative, was used to combine evidence from different studies. An empirical Bayes procedure with a normal-normal hierarchic model was then used to obtain a meta-analytic confidence interval for the overall median of the relative risks. The between-study variance was estimated using the method of moments approach described by DerSimonian and Laird (Controlled Clin Trials 1986;7:177-88). Combined (median) RR [95% confidence interval (CI)] and the number of studies included in our meta-analysis for different evaluative tests were as follows: DTS 4.6 (2.1-10.4) (n = 6); RNV 3.7 (1.6-8.3) (n = 5); AECG 2.7 (1.4-5.1) (n = 6), and DSE 6.2 (1.7-22.8) (n = 3). We conclude that while DTS, RNV, AECG, and DSE are effective (the 95% CIs are greater than 1.0) in predicting the cardiac outcome after vascular surgery, the data are not definitive in determining the optimal test (95% CIs for RR overlap). Future studies should include DSE, as this test shows great promise for predicting adverse cardiac events after vascular surgery.

A comparison of methods for the detection of myocardial ischemia during noncardiac surgery : automated ST-segment analysis systems, electrocardiography, and transesophageal echocardiography

Clinicians often fail to detect intraoperative ischemic electrocardiographic (ECG) changes when viewing oscilloscopes. Automated ST-segment monitors promise to increase the detection of such ECG changes. We investigated the capacity of two commercially available ST-segment monitors to detect intraoperative myocardial ischemia in patients at high risk for developing intraoperative myocardial ischemia during vascular and other noncardiac procedures. The ST-segment monitors were compared with two reference monitors: (a) printed eight-lead ECGs, as interpreted by a cardiologist, and (b) the presence of segmental wall motion abnormalities and thickening abnormalities detected by transesophageal echocardiography (TEE). We also examined the capacity of the printed ECG to diagnose myocardial ischemia when compared with TEE. We studied 44 patients who underwent TEE, printed multilead ECG, oscilloscope monitoring of leads V5 and II, and measurement or ST-segment deviation from the baseline using an automated Hewlett Packard ST-segment device. The sensitivities for the Hewlett Packard system were 40% for TEE-diagnosed myocardial ischemia and 75% for ECG-diagnosed ischemia. Comparison of the printed ECG with TEE revealed that ST-segment changes in the printed ECG, as analyzed by a cardiologist, were 25% sensitive and 62% specific for the detection of TEE-diagnosed myocardial ischemia. When T-wave inversions were added to ST-segment depression as a criterion for the diagnosis of myocardial ischemia by the printed ECG, the sensitivity of ECG for the detection of intraoperative myocardial ischemia, as determined by TEE, was 40% and specificity was 58%. Twenty-three of the 44 patients were simultaneously monitored in leads I, II, and V5 with an automated Marquette ST-segment monitor. In the 23 patients monitored with both Hewlett Packard and Marquette systems, the sensitivities (80% vs 100%, respectively) and specificities (67% vs 50%, respectively) were similar for ECG-diagnosed myocardial ischemia. Monitors of intraoperative myocardial ischemia often do not agree with each other; however, automated ST-segment monitors predict most ischemic changes seen on the printed ECG and can be used as an alarm to alert the clinician to examine the ECG.

Transesophageal echocardiographic monitoring of myocardial ischemia during vascular surgery

Transesophageal echocardiography (TEE) was used to detect segmental ventricular wall motion abnormalities (SWMAs) associated with ischemia in 49 high-risk patients who had 50 major vascular procedures, including 23 infrarenal aortic, five suprarenal aortic, 14 carotid, seven distal, and one axillofemoral reconstructions. A modified gastroscope tipped with an echocardiographic transducer was inserted into the esophagus and positioned behind the heart to obtain a reproducible cross-sectional view of the left ventricle at the level of the papillary muscles. Twelve patients (24%) had SWMA at baseline, probably representing areas of old infarction. Fourteen patients (28%) had new intraoperative SWMAs. Ten of 14 patients were successfully treated and wall motion was normalized. One of the four patients with persistent SWMA suffered a nonfatal subendocardial infarct; another patient suffered intraoperative cardiac arrest and died. No infarcts were documented in the 10 patients successfully treated. The mortality rate in the entire high-risk group was 6%. Alterations in ventricular wall motion were noted in almost 50% of high-risk patients undergoing major vascular surgery. Seventy-one percent of acute SWMAs were reversed without any evidence of myocardial infarction. TEE allowed early recognition of evolving myocardial ischemia and facilitated immediate and specific fluid and pharamcologic interventions. Continued application of this technique may reduce the incidence and morbidity of perioperative cardiac complications.

Assessment of retrograde cardioplegia distribution using contrast echocardiography

Retrograde cardioplegia has gained popularity in coronary and noncoronary cardiac operations. We have used contrast echocardiography in the open-chest canine model to compare the distribution of cardioplegia delivered antegrade in the aortic root versus retrograde through the coronary sinus, and to determine the effect of coronary occlusion on that delivery. With no coronary occlusion, antegrade cardioplegia was distributed to the entire left ventricle and septum whereas retrograde cardioplegia was distributed to the left ventricular free wall but had inconsistent delivery to the septum. Acute occlusion of the left circumflex coronary artery resulted in 57.06% +/- 9.52% of the left ventricle not being perfused by antegrade cardioplegia and occlusion of both the left circumflex and anterior descending coronary arteries caused a 65.46% +/- 18.5% reduction in perfusion by antegrade cardioplegia. Acute coronary occlusion had no effect on retrograde cardioplegia distribution. We conclude that retrograde cardioplegia is less homogeneous than antegrade cardioplegia in the intact coronary circulation but that retrograde cardioplegia preserves cardioplegia distal to acutely occluded coronary arteries. Furthermore, contrast echocardiography is a useful method of assessing myocardial perfusion and may have useful clinical applications.

Carotid endarterectomy: Perioperative and anesthetic considerations

AROTID endarterectomy (CEA) is increasingly performed in the United States and worldwide. In 1992, more than 90,000 CEAs were performed in the United States at an average cost of about

Premedication with clonidine does not attenuate suppression of certain lymphocyte subsets after surgery.

15,000 per procedure. ~ Because this procedure is becoming more common, anesthesiologists can benefit from a review of current practice and controversies in this field that can guide anesthetic strategy. This review discusses the natural history of carotid artery disease, current treatment modalities, and important issues in preoperative evaluation, with an emphasis on the problems posed by the patient with both severe carotid artery disease and severe coronary artery disease. Intraoperative and anestheuc management for CEA, including potential methods of cerebral and myocardial protection and the relative merits of different anesthetic techniques, as well as immediate postoperative management, are considered. DEFINITION, PROGNOSIS, AND TREATMENT OF CAROTID ARTERY DISEASE The most common cause of carotid artery occlusive disease is atherosclerosls, a systemic and progressive disease. It is bilateral in about half of all cases. The atherosclerotic plaque usually develops at the lateral aspect of the carotid artery bifurcation (Fig 1) and extends up into the internal and external carotid arteries (Fig 2). The plaque is composed of both cellular and acellular elements deposited in the subendothelial wall of the artery. Cellular elements principally consist of monocytes, fibrocytes, and smooth muscle cells; acel!ular elements are calcium, collagenous protein, lipids, and cholesterol. A fibrous cap develops at the interface between the blood and the antimal plaque. Disruption of the fibrous cap over a lipid deposiUon can lead to ulceration within the plaque. The embolization of thrombotic material or debris from the plaque can result in stroke or transient neurologic symptoms. The mechanisms of disease progression are not completely understood, but progressive disease is associated with increases in both cellular and acellular components of the plaque.

Use of electronic mail for postoperative follow-up after ambulatory surgery.

Sixty-four patients undergoing elective major surgery were randomly assigned into a double-blinded, placebo-controlled, clinical trial to test the hypothesis that premedication with clonidine would attenuate postoperative reductions in circulating lymphocytes. The treatment group (n = 28) received a clonidine skin patch (0.3 mg/d) and a 0.6-mg oral loading dose 60-90 min before surgery. The control group (n = 36) received placebo patches and pills. Absolute blood levels of the following lymphocyte subsets were measured before induction of a standardized general anesthetic (baseline) and the morning after surgery: CD2, CD3, CD4, CD8, CD20, CD56, and the CD4:CD8 ratio. Significant decreases in lymphocyte subsets CD2, CD3, and CD4 were found in both groups; CD56 was significantly decreased only in the placebo group. However, the extent of lymphocyte depletion from baseline to Postoperative Day 1 between the clonidine and placebo groups was not different. Plasma concentrations of epinephrine, norepinephrine, and cortisol were measured from blood samples drawn at 8:00 AM on Postoperative Day 1. Plasma norepinephrine levels were significantly lower among patients who received clonidine. However, no significant differences were found in plasma epinephrine or cortisol levels between the clonidine and placebo groups. With a clinical dose, clonidine did not prevent postoperative lymphocyte depletion. alpha2-Agonists may not suppress adrenocortical stress responses sufficiently to prevent postoperative immune suppression. Implications: Lymphocyte (white blood cell) counts often decrease after major surgery. We hypothesized that clonidine would reduce hormonal stress and blunt reductions in lymphocytes after major surgery. In a randomized trial, we found no differences from placebo in cortisol levels or lymphocyte changes. Lymphocyte levels did not predict infectious complications. (Anesth Analg 1998;87:1426-30)

CHOICE OF ANESTHESIA AND INTRAOPERATIVE MONITORING FOR LOWER EXTREMITY REVASCULARIZATION

The authors report on a patient who used electronic mail to report satisfactory recovery from ambulatory surgery and anesthesia. The potential benefits and pitfalls of using electronic mail for patient follow-up and communication, as well as research purposes, are reviewed. Potential benefits include cost savings, ease in collecting quality improvement data, and the potential for increased reporting of unpleasant events. Potential pitfalls include lack of universal access (with racial and socioeconomic differentials), privacy and security concerns, and potential slow responses to messages that might require emergent responses or actions.

Con: Pulmonary artery catheters are not routinely indicated in patients undergoing elective abdominal aortic reconstruction

The prevalence of significant coronary artery disease re-enforces the importance of careful preoperative and intraoperative management in patients undergoing lower extremity revascularization. This article presents a practical approach toward the evaluation of anesthetic risk and the proper use of anesthetic agents and monitoring devices to minimize morbidity. The role of general and regional anesthetic agents is discussed, and complications of both techniques are presented.