Noninvasive evaluation of hand circulation before radial artery harvest for coronary artery bypass grafting.

OBJECTIVE: Radial artery harvesting for coronary artery bypass may lead to digit ischemia if collateral hand circulation is inadequate. The modified Allen's test is the most common preoperative screening test used. Unfortunately, this test has high false-positive and false-negative rates. The purpose of this study was to compare the results of a modified Allen's test with digit pressure change during radial artery compression for assessing collateral circulation before radial artery harvest. METHODS: One hundred twenty-nine consecutive patients were studied before coronary artery bypass operations. A modified Allen's test was performed with Doppler ultrasound to assess blood flow in the superficial palmar arch before and during radial artery compression. A decreased audible Doppler signal after radial artery compression was considered a positive modified Allen's test. First and second digit pressures were measured before and during radial artery compression. A decrease in digit pressure of 40 mm Hg or more (digit DeltaP) with radial artery compression was considered positive. RESULTS: Seven of 14 dominant extremities (50%) and 8 of the 16 nondominant extremities (50%) with a positive modified Allen's test had a digit DeltaP of less than 40 mm Hg (false positive). Sixteen of 115 dominant extremities (14%) and 5 of 112 nondominant extremities (4%) with a negative Allen's test had a digit DeltaP of 40 mm Hg or more with radial artery compression (false negative). CONCLUSION: Use of the modified Allen's test for screening before radial artery harvest may unnecessarily exclude some patients from use of this conduit and may also place a number of patients at risk for digit ischemia from such harvest. Direct digit pressure measurement is a simple, objective method that may more precisely select patients for radial artery harvest. Additional studies are needed to define objective digital pressure criteria that will accurately predict patients at risk for hand ischemia after radial harvest.

A multisite comparison of student activities in the surgery clerkship.

The purpose of this study was to develop a method that would provide baseline data for the ongoing assessment of surgical clerkships at The University of Michigan Medical School. Of specific concern was the comparability of clerkship experiences among five different sites and the degree of variability in student experiences as the academic year progressed. Students (n = 168) in the required surgery clerkship at five affiliated sites completed a standardized daily log of the time spent on seven patient care activities and five formally structured educational activities for 1 week during each of five rotations. Analysis educational activities for 1 week during each five rotations. Analysis of variance and the Scheffe method for multiple comparisons were used to determine differences attributable to clerkship site and time of academic year. The results of the study revealed significant site-, rotation-, and activity-specific variations in the surgery clerkship experiences. However, the students at each of the five sites distributed their time almost equally between patient care and formal educational activities. The study has provided a model for assessing variability and change in the surgery clerkship program both within individual sites and across an entire affiliated hospital system. The instruments and methods are presented for adoption by other institutions with similar goals.

Oral examinations: actual and perceived contributions to surgery clerkship performance.

Controversy persists regarding the validity, utility, and practicality of oral examinations. This study of a recent 3-year experience at the University of Michigan Medical School was undertaken to determine the value of the oral examination in the required junior year surgery clerkship. Multiple regression analysis of the relationship between the oral examination and ward grades, written examination grades, and the final grades for the clerkship years 1980 to 1981 (n = 198), 1981 to 1982 (n = 234), and 1982 to 1983 (n = 215) (classes of 1982, 1983, and 1984) revealed significant correlation between the oral examination and other evaluation parameters. Stepwise regression analysis revealed that the oral examination contributed unique information to final grade determination. Two surveys identified faculty and student opinion regarding the oral examination. The results were consistent during the 3-year period of study. Faculty and student opinion regarding the examination as an evaluation process and motivational device were positive, as was opinion regarding the breadth and depth of knowledge tested and the examination as a learning experience and an accurate reflection of students' performance. Both faculty and students agreed that the examination was worth the time and effort invested by faculty, was an appropriate evaluation process, and was a source of worthwhile faculty and student interaction.

Measurement of metabolism in multiple organ failure.

Despite the emphasis on surgical nutrition, clinical research and practice are usually based on gross estimation of caloric requirements and no specific knowledge of caloric balance. One reason for this is the difficulty of measuring O2 and CO2 exchange in critically ill patients. We designed a system for intensive care unit (ICU) bedside measurement of O2 consumption (VO2), CO2 production (VCO2), respiratory quotient (RQ), and indirect calorimetry (E). We measured these variables daily in 57 surgical ICU patients at risk for multiple organ failure. Measured VO2 and E varied widely (+/- 40%) from estimated values. Seventeen patients had a cumulative negative balance of at least 10,000 calories; 13 died. This caloric deficient was reversed by caloric intake in three of these patients; one died. Fifteen patients had positive caloric balance. Only four of these died, but the CO2 load produced by hypercaloric feeding created ventilator weaning problems in some patients. Ventilator weaning was facilitated by decreasing total calories and substituting fat for carbohydrate to reduce the RQ. The incidence of multiple organ failure was higher in patients with large caloric deficits, although cause and effect are not inferred. We conclude that respirometry and indirect calorimetry are helpful for management and essential for nutritional research.

Chronic total renal artery occlusion: effects of treatment on secondary hypertension and renal function.

Chronic total occlusion of 42 main renal arteries was documented by arteriographic studies in 25 female and 15 male patients being evaluated for drug-resistant hypertension. Arteriosclerotic lesions affected 35 patients, and fibrodysplastic obstructions occurred in five. Hypertensive urographic studies showed lateralization to the affected kidney in all 31 studies obtained. Renal vein renin activity lateralized with a mean ratio of 3.88 in the 24 patients studied. In 15 patients, mean renal: systemic renin indices (RSRI) of 2.39 confirmed ischemic kidney renin hypersecretion, and a mean RSRI of 0.03 confirmed contralateral suppressed secretion. Affected kidney lengths averaging 9.4 cm were significantly smaller than the 13.0 cm length of kidneys without occluded arteries. Thirty patients with 31 occluded arteries underwent renal artery bypass (18), endarterectomy (2), or nephrectomy (11). There were two perioperative deaths. Eighty-nine percent of survivors benefited in regard to hypertension control, and 47% exhibited improved renal function. Nonoperative treatment of 10 patients was associated with frequent progression of renal failure and inadequate blood pressure control. This experience documents the appropriateness of surgical therapy for secondary hypertension caused by chronically occluded renal arteries.

Abdominal aortic coarctation and segmental hypoplasia.

Functionally significant, nonatherosclerotic, noninflammatory, concentric and tubular stenoses of the abdominal aorta, 4 to 16 cm in length, were encountered in five male and five female patients 11 to 49 years old. Seven patients were younger than 19 years of age. Aortic branch stenoses were common, affecting splanchnic vessels in seven patients and renal arteries in eight patients. The pathogenesis of the aortic constrictive lesions remains unknown, but it may be related to developmental error or aortic growth arrest. Existence of multiple renal arteries in 70% of these patients lends support to the developmental hypothesis. Intimal fibroplasia characterized stenotic aortic tissue. Severe hypertension was common, with the mean preoperative arterial pressure being 200/119 mm Hg. Thoracoabdominal bypass was undertaken in eight patients, being combined with renovascular reconstruction on five occasions. Two patients underwent patch graft aortoplasty with bilateral renal revascularization. Therapeutic results were classified as excellent six times and as good four times. Single-stage arterial reconstructions are the preferred method of treatment for abdominal aortic coarctation or segmental hypoplasia with associated aortic branch disease.

Resident selection: applicant selection criteria compared with performance.

One hundred three surgical house officers, 41 in general surgery and 62 in specialty surgery, entered the residency program from 1975 through 1979. Their application data, including the National Board of Medical Examiners test part I scores, preclinical course honors, clinical course honors, surgical clerkship honors, election to Alpha Omega Alpha (AOA), published research, medical school grading system, medical school rating, and National Resident Matching Program rank, were tabulated. Each house officer's performance was assessed by monthly faculty evaluation and by annual standard American Board of Surgery In-Training Examination (ABSITE) score through the second year of the program. The application data were compared with the performance data to determine significant indicators of success. Factor analysis computed on the monthly evaluation forms identified a knowledge factor and an interpersonal skills factor. Statistical analyses were used to study the relationships among the independent (preentry) variables and the knowledge, interpersonal skills, and ABSITE postentry variables. The results were significant (P less than 0.05) for medical school honors, election to AOA, and medical school grading system. No significance was found for the remaining preentry variables. The knowledge and interpersonal skill evaluation scores for the house officer I and II years were significantly correlated. Although the postentry assessment of knowledge correlated with certain applicant data, the assessment of interpersonal factors was not statistically related.

Abdominal aortic aneurysm rupture: statistical analysis of factors affecting outcome of surgical treatment.

One hundred sixteen patients underwent surgery for ruptured abdominal aortic aneurysms with intraoperative and overall mortality rates of 20.7% and 51.7%, respectively. The correlation of multiple factors to morbidity and mortality was assessed with detailed statistical analysis. Eight preoperative factors were identified as predictors of mortality. Increased intraoperative mortality rates were associated with heart disease (29%), hypertension (30%), flank ecchymoses (57%), and pulsatile abdominal mass (24%). Increased intraoperative and overall mortality rates were associated with preoperative hypotension (39%, 78%) and BUN levels higher than 30 mg/dl (47%, 82%). Increased overall mortality rates were associated with creatinine levels higher than 3 mg/dl (71%) and a hematocrit of 30.0 to 32.5 vol% (75%) (P less than 0.05). Seven intraoperative factors were identified as predictors of mortality. Increased postoperative mortality rates were associated with a duration of operation of more than 400 minutes (100%), hypotension lasting longer than 110 minutes (88%), estimated blood loss more than 11,000 ml (75%), blood transfusion more than 17 U (68%), fluid administration in excess of 7000 ml (70%), and a blood pressure lower than 100 mm Hg at the conclusion of the operation (88%). Cardiac arrest was associated with increased intraoperative and overall mortality rates (77%, 82%) (P less than 0.05). In general these factors cannot be controlled by the surgeon, and future significant reduction in the operative mortality rate may be possible. These findings support the general concept of aggressive elective resection of abdominal aortic aneurysms.

Discriminant arteriographic criteria in the management of forearm and hand ischemia.

Fifty-five patients (33 male and 22 female), 3 to 73 years in age, underwent aortic arch and selective upper extremity arteriography for the evaluation of forearm and hand ischemia from 1971 to 1980. Fifty-one patients had organic occlusive lesions (12 subclavian, 15 axillobrachial, 17 radial-ulnar, and 7 palmar-digital), including distal forearm and hand emboli, as a consequence of proximal occlusive disease in nine patients (5 subclavian, 2 axillobrachial, and 2 radial-ulnar). The remaining four patients had vasospastic disease. Major arteriographic findings of obstructive disease were defined by: morphology of lesions, symmetry or asymmetry of obstructions, segmental versus tandem lesion distribution, and the resultant pattern of collateral circulation. Vasodilatory pharmacoangiography with magnification technique frequently facilitated evaluation of digital and collateral vessels. Therapeutic interventions were dictated by clinical data heavily weighed by the arteriographic examination. Limited arteriographic studies would have been misleading in the evaluation of many patients.

Splanchnic arteriosclerotic disease and intestinal angina.

Twenty-three patients (13 women and ten men, 33 to 73 years old) underwent reconstruction of 33 major splanchnic arteries for relief of symptomatic intestinal ischemia. All patients experienced postprandial abdominal pain and lost weight (average, 12.8 kg). Arterial reconstructions (32 bypass procedures and one endarterectomy with patch-graft arterioplasty) were undertaken with both autogenous saphenous vein (24) and prosthetic condults (nine). Revascularizations involved the superior mesenteric (21), celiac (five), hepatic (four), splenic (two), and inferior mesenteric (one) arteries. There were four postoperative deaths; three occurred after emergent secondary attempts at intestinal revascularization. All of the 19 patients who survived benefited from operative intervention.

Clinical significance of arteriosclerotic femoral artery aneurysms.

One hundred seventy-two arteriosclerotic femoral artery aneurysms in 100 male patients, 47 to 91 years old, were evaluated. They were bilateral in 72% of the patients, and were associated with aortoiliac aneurysmal disease in 85% and with popilteal artery aneurysms in 44%. Femoral artery aneurysms were asymptomatic in 40 patients. Thirteen patients with thromboembolic episodes and two with rupture had ischemic limbs. Thirty-eight patients underwent primary operation for 50 femoral aneurysms, including 36 lower extremity arterial reconstructions, ten aortofemoral bypasses, one arterial ligation, and three amputations. Two operative deaths occurred, both associated with concomitant aortic surgery. Only three of 105 aneurysms in 58 patients followed nonoperatively were associated with later major limb-threatening complications. The low complication rate attending small, bland aneurysms justified nonoperative management. Large or symptomatic aneurysms warrant early operative intervention.

Extracranial internal carotid artery dissections: noniatrogenic traumatic lesions.

Noniatrogenic traumatic extracranial internal carotid artery dissections were encountered in six patients (five men and one woman) 31 to 62 years old. All but one had overt cerebral ischemia manifest by paresis (three), sensory deficits (three), aphasia (three), or amaurosis fugax (two), One patient had an asymptomatic carotid artery bruit. Cerebral arteriography established the diagnosis in all cases. Internal carotid artery impingement between the mandible and transverse processes of the second and third cervical vertebrae, or undue stretching over these vertebral structures, were the most likely primary mechanisms of injury. Secondary complications, a result of distal thromboembolism, were evident in two patients. Direct cerebral revascularization, staged internal carotid artery constriction and ligation, as well as intensive nonoperative therapy were valid therapeutic options. There were no deaths. Treatment relieved transient ischemic symptoms or arrested progression of established neurologic deficits in each case. In select patients, early surgical intervention may lessen attending neurologic sequelae.

Nonpenetrating subclavian artery injuries.

Nonpenetrating subclavian artery trauma, a potentially catastrophic injury, has been recognized more frequently with the liberal use of angiography in evaluating blunt cervicothoracic trauma. Six patients, five men and one woman, recently underwent surgical treatment at the University of Michigan Hospital for blunt injury of the subclavian artery. The diagnoses were established by arteriography. Physical findings, chest roentgenograms, and results of noninvasive vascular evaluation were found to be nonspecific or unreliable. Operative treatment with resection of the injured arterial segments and either primary anastomosis or bypass grafting resulted in restoration of distal, upper extremity blood flow in all of the cases. One patient died 20 days after trauma from a severe associated cerebral injury. Among the five survivors, residual soft tissue and neurologic injury compromised full recovery in three. Thus, only two of the six patients survived without sequelae, a fact that underscores the seriousness of this type of subclavian artery injury.

Developmental occlusive disease of the abdominal aorta and the splanchnic and renal arteries.

Developmental occlusive disease of the abdominal aorta and the renal and splanchnic arteries represent an unusual vascular condition. When unrecognized or untreated this disease is associated with premature death, usually from severe secondary hypertension as a consequence of renovascular stenotic lesions. Strong circumstantial evidence indicates that developmental abnormalities occurring during the fetal union of the two dorsal aortae account for most of the occlusive lesions affecting the abdominal aorta and its visceral branches in these patients. Complete arteriographic studies are necessary to confirm and accurately delineate the disease process. Surgical treatment, which often encompasses complex vascular reconstructive efforts, affords excellent results when carefully planned and executed.

Aorto-iliac reconstruction with Dacron double velour.

Dacron double velour grafts were evaluated in an animal preparation and utilized in 318 patients undergoing elective aortic reconstruction for aneurysmal and occlusive disease. Dacron double velour forms an adherent inner lining, preclots easily, is soft, pliable and easy to handle and suture. Clinical studies revealed excellent patency with a low incidence of prosthesis related complications. No clinical evidence of overt prosthesis failure, dilation, aneurysm formation, or pseudointimal embolization occurred during an average follow-up of 2.3 years.

Incidence and pathophysiologic significance of infected carotid artery plaque.

It is unknown whether an association exists between infectious microorganisms and atherosclerosis. Eighty consecutive patients undergoing carotid endarterectomy were studied to detect for bacterial or virus infections in removed carotid atherosclerotic plaques. Twenty-one patients (25%) were found to have positive cultures for bacteria of the carotid plaques. Three patients (4%) did not have bacterial contamination of controlled cultures of the skin. Of these three patients, two grew diptheroids and one grew staphylococcus. The control cultures of the skin demonstrated that 25 patients (31%) grew diphtheroids and 29 (36%) grew staphylococcus. Five patients grew both organisms. There was no evidence of colonization within the atheromatous plaque material in histologic studies of the three patients that had positive cultures of their plaque. All viral cultures were negative. The positive carotid cultures found were most likely due to contamination from the skin. This study demonstrates the unlikelihood of bacterial or virus infections as either an etiologic or a pathogenetic factor in carotid artery atherogenesis.

Atherosclerotic extracranial carotid artery aneurysms.

Twenty-four atherosclerotic extracranial carotid artery aneurysms were encountered in 21 patients during a 25-year period. These represented 46% of all extracranial carotid artery aneurysms diagnosed at the University of Michigan during this period. Neurologic symptoms including amaurosis fugax, transient ischemic attacks, and stroke were present in 50% of the patients. An asymptomatic pulsatile neck mass occurred in 33%. Surgical therapy was undertaken for 18 aneurysms, and nonoperative treatment was pursued in the remaining six aneurysms. Operative therapy included 14 aneurysmectomies and four aneurysmorraphies. There were no surgical deaths. Transient perioperative neurologic deficits affected three of these patients (17%), and one individual (5%) experienced a permanent deficit. Transient cranial nerve deficits occurred in three patients (17%), and a permanent deficit was noted in one patient (5%). During a 7.6-year follow-up period no late strokes occurred among patients who were operated on. Nonoperative therapy was associated with three ipsilateral strokes during a mean follow-up period of 6.3 years. Atherosclerotic extracranial carotid artery aneurysms were associated with an exceptionally high stroke rate (50%) if treated nonoperatively. Prevention of late stroke justifies surgery, although perioperative neurologic deficits may accompany this therapy more often than with nonatherosclerotic carotid artery aneurysms.