Occlusive Disease In Patients Research Articles

Determinants of peak V(O2) in peripheral arterial occlusive disease patients.

Peripheral arterial occlusive disease (PAOD) patients with intermittent claudication are functionally limited and deconditioned. This study examined whether peak aerobic capacity (V(O2) peak) was associated with PAOD severity, muscle mass, and comorbidities in 109 PAOD patients (93 men and 16 women) aged 48-86 years. The V(O2) peak (1.12+/-0.34 L/min), percentage body fat (30.6+/-8.3%), lean tissue mass of the total body (51.4+/-8.4 kg), lean tissue mass of the legs (16.6+/-3.0 kg), and appendicular skeletal mass (22.8+/-4.2 kg) were determined. The lean tissue mass of the total body (r = .44), lean tissue of the legs (r = .43) and resting ankle/brachial systolic pressure index (ABI; r = .41) correlated with peak V(O2) (all p < .001). None of the comorbidity variables (obesity, arthritis, coronary artery disease, hypertension, diabetes, and smoking history) were significantly associated with peak V(O2) except smoking status. The final model for the prediction of peak V(O2) included lean tissue mass of the legs, resting ABI, smoking status, and ABI x smoking status (r2 = .37,p < .001). In older patients with intermittent claudication, lean tissue mass is an important determinant of physical performance independent of PAOD severity and smoking status. Prevention of muscle atrophy may preserve ambulatory function and peak exercise capacity in older PAOD patients.

Increased endogenous nitric oxide production induced by physical exercise in peripheral arterial occlusive disease patients

The effects of 14-day physical exercise or iloprost treatment (0.5–2 ng/Kg/min) on endogenous nitric oxide production and neutrophil adhesion were evaluated in 20 patients with peripheral arterial occlusive disease (Fontaine Stage II). Peripheral venous blood samples and 4-h urine samples were collected before, immediately after 14 days of therapy and 7–10 days after therapy in order to evaluate neutrophil adhesion, nitrite/nitrate and cGMP excretion rates. A longer pain free walking distance was observed after exercise, compared to iloprost (> 500 m in 3 10 subjects). Urinary nitrite/nitrate, as well as cGMP concentrations, significantly increased after exercise. Nitrite/nitrate excretion rate inversely correlated to neutrophil adhesion. No variations were observed in these parameters in iloprost treated patients. The improvement in claudication and the transient increase in urinary nitrite/nitrate suggest a possible nitric oxide-dependent mechanism for the clinical efficacy of physical exercise. The results from the present and previous observations indicate that, besides pharmacological treatments, a regular aerobic exercise improves peripheral arterial occlusive disease.

Pilot study of prevalence of asymptomatic peripheral arterial occlusive disease in patients with diabetes attending a hospital clinic

AbstractIn a pilot study, we have estimated the crude prevalence of asymptomatic peripheral arterial occlusive disease (PAOD) in diabetic patients attending a hospital clinic, using the sensitive Doppler ultrasound measurement of systolic ankle brachial pressure index (ABPI). This was compared with the available clinical methods of PAOD detection, ie peripheral pulse palpation. We have also investigated whether the measurement of toe systolic pressure (TSP) improved the detection rate of PAOD amongst those who had a normal ABPI. Of the 48 patients studied, 12 had palpable dorsalis pedis and posterior tibial pulse and 36 had absent pulse. Patients were of both types of diabetes mellitus, had no history of cardiovascular or cerebrovascular disease and did not have symptoms suggestive of intermittent claudication. An ABPI value of&gt;0.9 was taken as normal. TSP was assessed by a strain gauge method. All patients who had palpable pulses had an ABPI &gt; 1.0 with median (range) 1.10(1.01–1.30). Of those who had impalpable pulses, 18 patients had evidence of significant peripheral arterial insufficiency with an ABPI median (range) of 0.76 (0.49–0.89) and 18 patients had a normal ABPI with median (range) of 1.08 (0.92–1.25). TSP measurements were not different from the ankle systolic pressure. The study groups were no different in terms of their duration of diabetes, smoking habit, Body Mass Index or glycated haemoglobin levels, but those in the group with a low ABPI were significantly older, p&lt;0.05. The prevalence of asymptomatic PAOD in our study cohort was 33% We conclude that palpable pulses are a predictor of normal ABPI, but impalpable pulses are not a strong predictor of PAOD.

Analysis of endovascular graft treatment for aortoiliac occlusive disease: what is its role based on midterm results?

To analyze the authors' midterm results (up to 4 years) using endovascular grafts to treat aortoiliac occlusive disease in patients with limb-threatening ischemia. Endovascular grafts are being used to manage some aortoiliac lesions formerly treated by aortofemoral or extraanatomic bypass grafts. However, widespread acceptance of these new grafts depends on their late patency and clinical utility. Between January 1993 and December 1997, 52 patients with aortoiliac occlusive disease were treated with endovascular grafts. The primary indication for treatment was gangrene or ulceration in 42 patients (81%) and rest pain in 10 patients (19%). Sixteen patients had symptomatic contralateral limbs that were also treated, and 27 (52%) patients required a synchronous infrainguinal bypass. Results up to 4 years were evaluated by life table analysis. Forty-six (88%) of the patients had complete follow-up of 3 to 57 months (median 22 months). Six patients were lost to follow-up at a mean of 20 months after surgery. The 4-year primary and secondary patency rates for the endovascular grafts were 66.1% and 72.3% respectively. Six patients required a major amputation, and the limb salvage rate was 88.7%. Four-year patient survival was 37%, with 23 patients dying during this follow-up period. Endovascular grafts can often be used when conventional procedures are contraindicated or technically impractical. These grafts are a valuable alternative to extraanatomic and aortofemoral bypasses in high-risk patients with aortoiliac occlusive disease and critical ischemia.

Smoking history is related to free-living daily physical activity in claudicants.

To determine whether smoking history was related to free-living daily physical activity in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication, and whether the effect of smoking history on physical activity level persisted after controlling for group differences in ambulatory function, peripheral circulation, and body composition. Patients were separated into three groups: those who never smoked (N = 35), those who had a lower pack-year history of smoking (< or =40 pack-yr; N = 33), and those who had a higher pack-year history (>40 pack-yr; N = 30). Free-living daily physical activity was assessed by activity monitors (an accelerometer and a pedometer) worn on each hip over 2 consecutive weekdays. Patients also were characterized on ambulatory function, peripheral circulation, and body composition because of their relationship with physical activity. A progressive decline (P < 0.001) in free-living daily physical activity with increasing smoking exposure was obtained from the accelerometer in the nonsmokers (482 +/- 36 kcal x d(-1); mean +/- SE), smokers with a lower pack-year history (361 +/- 37 kcal x d(-1)), and smokers with a higher pack-year history (227 +/- 23 kcal x d(-1)). A similar decline was found with the pedometer data (P < 0.001). After controlling for group differences in 6-min walk distance and in calf transcutaneous heating power, group differences in free-living daily physical activity were no longer significant. Progressive decrements in free-living daily physical activity with greater levels of smoking exposure in PAOD patients are primarily due to smoking-related impairments in ambulatory function and peripheral circulation.

31P MRS studies of exercising human muscle at high temporal resolution.

Methods for measuring mitochondrial activity from 31P magnetic resonance spectroscopy data collected during and after exercise were compared in controls, weight lifters, and peripheral vascular occlusive disease (PVOD) patients. There were trends toward increasing mitochondrial activity during exercise in order from PVOD patients, moderately active controls, highly active controls, to weight lifters. Results from PVOD patients show divergence of some measures due to 1) the non-exponential nature of phosphocreatine recovery, and 2) potential breakdown of [ADP] control of the mitochondria due to lack of oxygen (for Qmax calculation). These results demonstrate the utility of obtaining and directly analyzing high time resolution data rather than assuming monoexponential behavior of metabolite recovery.

THE EFFECT OF CIGARETTE SMOKING STATUS ON SIX-MINUTE WALK DISTANCE IN PATIENTS WITH INTERMITTENT CLAUDICATION

516 The purpose was to dermine the influence of smoking status on six-minute walk distance in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. 415 patients between the ages of 42 and 88 were recruited. The self-reported smoking status consisted of 182 current smokers, 196 former smokers, and 37 patients who had never smoked. We recorded six-minute walk distance, as well as other measures which might explain group differences in six-minute walk distance such as age, body composition, self-reported ambulatory function, self-reported physical activity, and standard peripheral hemodynamics. Non-smokers walked further (413 ± 14 m; mean ± standard error) than either current (352 ± 7 m;) or former smokers (370 ± 7 m) (p < 0.05). Ankle/brachial index, self-reported physical activity, and self-reported ambulatory function were independent predictors of six-minute walk distance (R2 = 0.34, p < 0.001), explaining group differences in ambulatory ability. In conclusion, the greater six-minute walk distance of the non-smokers is associated with higher ankle/brachial index, higher self-reported physical activity level, and higher ambulatory function. Supported by NIA (K01-AG00657 and P60-AG12583).

Relationship between free-living daily physical activity and peripheral circulation in patients with intermittent claudication.

The purpose of this study was to determine the relationship between free-living daily physical activity and peripheral circulation under resting, reactive hyperemia, and maximal exercise conditions in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. Sixty-one PAOD patients (age = 70 +/- 6 years, ankle/brachial index [ABI] = 0.57 +/- 0.24) were recruited from the Vascular Clinic at the Baltimore Veterans Affairs Medical Center and from radio and newspaper advertisements. Free-living daily physical activity was measured as the energy expenditure of physical activity (EEPA), determined from doubly labeled water and indirect calorimetry. Patients also were characterized on ankle/brachial index, calf blood flow, calf transcutaneous oxygen tension (TcPO2), and calf transcutaneous heating power (TcHP). ABI and calf blood flow served as markers of the macrocirculation of the lower extremity, while TcPO2 and TcHP served as markers of the microcirculation. The claudication patients were sedentary, reflected by a mean EEPA value of 486 +/- 274 kcal/day. EEPA was related to calf TcHP at rest (282 +/- 24 mW; r = -0.413, p = 0.002), after postocclusion reactive hyperemia (275 +/- 22 mW; r = -0.381, p = 0.004), and after maximal exercise (276 +/- 20 mW; r = -0.461, p<0.001). ABI, calf blood flow, and calf TcPO2 were not related to EEPA under any condition. In conclusion, higher levels of free-living daily physical activity were associated with better microcirculation of the calf musculature in older PAOD patients with intermittent claudication.

Rehabilitation of Lower Extremity Amputation Due to Peripheral Arterial Occlusive Disease in Patients with End-Stage Renal Failure

Rehabilitation of elderly patients with lower limb amputation and additional severe disease gives rise to controversy. End-stage renal disease (ESRD) is an example of such a disease, frequently leading to local complications of prosthetic fitting due to considerable changes in limb volume. In this retrospective study the authors present data on rehabilitation outcome of a large group of patients with end-stage renal failure and amputation of the lower limb due to peripheral arterial occlusive disease. Often diabetes with its additional comorbidities is the common underlying cause for both. From 1987 to 1996, 30 patients (aged 50 to 89, average 65 years) with ESRD and either unilateral or bilateral amputation were referred for in-patient rehabilitation (group I). The control group consisted of 319 patients without severe renal disease (group II). Both groups were similar regarding distribution of age and gender. There was no statistically significant difference with respect to prosthetic restoration and duration of rehabilitation between the two groups. The difference in the overall rehabilitation rate between the groups, with 77% of limb-wearers in group I compared with 62% in group II, was not statistically significant. The percentage of diabetics in group II was 56%, but as high as 77% in group I (p &lt; 0.05), in 57% with signs of diabetic microangiopathy. With belowknee amputation (BKA) in only 34% in group II compared with 77% in group I, this number is disproportionally low (p &lt; 0.05), unfortunately representing the amputation rates of surgical units in the city. When matched for level of amputation, subgroup analysis revealed no significant difference for clinical outcome in terms of prosthetic fitting or length of stay. The authors conclude that rehabilitation of elderly patients with ESRD with lower limb amputation is worthwhile and justifiable in view of anticipated lower budgets.

Cigarette smoking shortens the duration of daily leisure time physical activity in patients with intermittent claudication.

The authors determined (1) whether peripheral arterial occlusive disease (PAOD) patients who smoke have a reduction in either the duration or intensity of daily physical activities compared with nonsmoking patients, and (2) whether group differences in the pattern of physical activity persisted after controlling for potential confounding variables. A total of 170 smokers and 201 nonsmokers who had quit smoking for at least 1 year prior to investigation were studied. Physical activity patterns were measured using the Minnesota Leisure Time Physical Activity (LTPA) questionnaire. Patients also were characterized on potential covariates such as demographics, comorbid conditions, cardiovascular risk factors, ambulatory measures, peripheral hemodynamics, and anthropometric measures. The smokers were 37% less physically active than the nonsmokers (87 +/- 90 versus 139 +/- 121 kcal/day; P = 0.027). The reduced total LTPA in the smokers was due to a 28% shorter duration of performing activities (26 +/- 7 versus 36 +/- 22 min/day; P = 0.031), and a 3% lower mean intensity of the activities (3.3 +/- 1.0 versus 3.8 +/- 0.8 kcal/min; P = 0.038). The distance score on the Walking Impairment Questionnaire and the hip circumference were significant covariates of the LTPA measures. After adjusting for these covariates, the total LTPA remained 29% lower in the smokers (P = 0.039), the mean daily duration of LTPA remained 20% lower (P = 0.043), but the mean intensity of LTPA was no longer different between the groups. Compared with their nonsmoking counterparts, claudicants who smoke have a reduced total LTPA because they engage in activities of similar intensity for a shorter duration of time.

Fibrinogen and mortality in chronic critical limb ischaemia.

Plasma fibrinogen predicts cardiovascular events in patients with stable peripheral arterial occlusive disease, but its predictive value in patients with chronic critical limb ischaemia, a condition associated with a high risk of death, is unknown. A prospective cohort study. Determination of fibrinogen and other potential predictors during clinic-based work-up of patients admitted for diagnostic and therapeutic evaluation. A total of 108 patients (72 +/- 10 years, 78 males) with atherosclerotic occlusive disease and critical limb ischaemia (pain at rest and/or trophic lesions) followed up for a median period of 1.6 years). (range: 8 days-5.5 years; 218 patient-years). Total mortality. Forty-five deaths (71% cardiovascular) occurred during the follow-up. Baseline fibrinogen was higher in those who died in the early follow-up period (first 6 months), as were white cell count and serum creatinine, while haematocrit was lower. Plasma fibrinogen values correlated positively with white cell count, and negatively with haematocrit; other cardiovascular prognostic factors did not differ. Only plasma fibrinogen predicted survival independently in multivariate age-corrected Cox regression analysis. Relative risk of death doubled for each standard deviation above the mean and increased with each tertile increase in fibrinogen. Fibrinogen predicted death in these elderly arteriopaths with critical limb ischaemia, particularly those who died in the first months following critical ischaemia. Inflammatory stimuli secondary to severely defective tissue oxygenation and possibly sepsis and necrosis, might have stimulated fibrinogen, an acute-phase reactant, thereby compromising organ perfusion through increased blood viscosity and/or promoting thrombosis.

Prediction of peak oxygen consumption in patients with intermittent claudication.

Determination of peak oxygen consumption (VO2peak) is considered important for assessing a patient's functional capacity and for exercise prescription. However, the equipment necessary to obtain accurate determination of VO2peak is not always available in clinical settings. The present study sought to develop an equation to estimate VO2peak in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication and to determine independent predictors of VO2peak in this population. One hundred and fifty-seven patients with intermittent claudication were assigned to either a validation group (n = 105) or a cross-validation group (n = 52). Medical history, height, weight, body mass index (BMI), age, gender, smoking status, resting and postexercise ankle/brachial systolic pressure index (ABI), and time to maximal claudication pain and maximal heart rate from an incremental graded exercise test (GXT) were used as potential independent predictors of VO2peak. Time to onset of maximal claudication pain, maximal heart rate, and BMI were all independently associated with VO2peak. These variables were used to estimate VO2peak by the following equation: VO2peak (mL/kg/min) = (0.00872 x maximal claudication pain time [sec]) + (0.02839 x maximal heart rate [b/min]) - (0.12034 x BMI) + 10.11411 r = 0.71, r2 = 0.50, standard error of estimate = 2.02 mL/kg/min, p < 0.0001There was no significant difference between the estimated and actual VO2peak in the cross-validation group, and the coefficient of variation between estimated and actual VO2peak in this group was 18.3%. There was no significant difference between the correlation coefficient for the relationship between estimated and actual VO2peak in the cross-validation group (r = 0.61) and the multiple correlation coefficient from the validation group (r = 0.71). Results of this study suggest that a multiple regression equation can be used to estimate VO2peak in patients with intermittent claudication by measuring time to maximal claudication pain and maximal heart rate from a GXT and by measuring BMI.

The clinical utility of a six-minute walk test in peripheral arterial occlusive disease patients.

To determine the test-retest reliability of the distance covered and the steps taken to complete a 6-minute walk test by peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. To determine the relationship between the total distance and steps covered during the 6-minute walk test and clinical measures of PAOD severity. Cross-sectional design. The Claude Pepper Older Americans Independence Center at the University of Maryland at Baltimore. Sixty-four PAOD patients between the ages of 45 and 88 years (age = 68 +/- 7 years, ankle/brachial index (ABI) = .61 +/- .19) were recruited from the Vascular Clinic at the Baltimore Veterans Affairs Medical Center and from radio and newspaper advertisements. Patients were assessed on a 6-minute walk test and a treadmill graded exercise test. A second 6-minute walk test was administered approximately 1 week later. Patients also were characterized in regard to blood pressure in the arms and legs, ABI, anthropometry, body composition, and physical activity. The distances walked during the two 6-minute walk tests were similar (350 +/- 78 m vs 360 +/- 73 m), resulting in a high reliability coefficient (R = .94) and a low coefficient of variation (10.4%). The total steps taken during the 6-minute walk test also were similar (562 +/- 113 steps vs 587 +/- 107 steps), resulting in a high reliability coefficient (R = .90) and a low coefficient of variation (11.7%). Furthermore, the 6-minute walking distance correlated with the distances to onset (r = .346, P = .007) and with maximal claudication pain (r = .525, P < .001) during the treadmill test as well as with ABI (r = .552, P < .001). The 6-minute walk test yields highly reliable measurements, which are related to the functional and hemodynamic severity of PAOD, in patients with intermittent claudication.

Relationship between free-living daily physical activity and ambulatory measures in older claudicants.

The purpose of this study was to determine the relationship between free-living daily physical activity and ambulatory measurements in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. Thirty-four older, nonsmoking PAOD patients with intermittent claudication (age=69.0 +/- 6.0 years, ankle/brachial index [ABI] =0.63 +/- 0.18) were recruited from the Vascular Clinic at the Baltimore Veterans Affairs Medical Center and from radio and newspaper advertisements. Energy expenditure of physical activity (EEPA) was determined by using doubly labeled water and indirect calorimetry techniques. Patients were also characterized on claudication distances and peak oxygen uptake during a graded treadmill test, 6-minute walking distance, weight, body mass index, and percent body fat. The claudication patients were sedentary, as EEPA was 362 +/- 266 kcal/day. EEPA was related to the 6-minute walk distance (369 +/- 68 meters; r=0.629, P<0.001), to the number of steps taken during 6 minutes (605 +/- 99 steps; r=0.485, P=0.008), to the treadmill distance to maximal claudication (313 +/- 131 meters; r=0.470, P=0.010), and to the time to relief of pain (6:21 +/- 3:57 min:sec; r=-0.417, P=0.017). None of the other ambulatory and body composition measurements were correlated with EEPA. In conclusion, a reduction in free-living daily physical activity was associated with a decrease in ambulatory ability and with more severe intermittent claudication in older PAOD patients.

PREDICTION OF PEAK OXYGEN CONSUMPTION IN PATIENTS WITH INTERMITTENT CLAUDICATION

Determination of peak oxygen consumption (VO2peak) is considered important for assessing a patient's functional capacity and for exercise prescription. However, the equipment necessary to obtain accurate determination of Vo2peak is not always available in clinical settings. The present study sought to develop an equation to estimate VO2peak in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication and to determine independent predictors of VO2peak in this population. One hundred and fifty-seven patients with intermittent claudication were assigned to either a validation group (n = 105) or a cross-validation group (n = 52). Medical history, height, weight, body mass index (BMI), age, gender, smoking status, resting and postexercise ankle/brachial systolic pressure index (ABI), and time to maximal claudication pain and maximal heart rate from an incremental graded exercise test (GXT) were used as potential independent predictors of VO2peak. Time to onset of maximal claudication...

The effect of cigarette smoking on free-living daily physical activity in older claudication patients.

The purposes of this study were (1) to determine whether peripheral arterial occlusive disease (PAOD) patients who smoke have a lower free-living daily physical activity than nonsmoking patients and (2) to determine whether the difference in physical activity persisted after controlling for potential confounders such as PAOD severity, age, body composition, and peripheral circulation. Thirty-four smokers (45.5 +/-9.8 years of smoking) and 43 nonsmokers (former smokers who had a smoking history of 35.0 +/- 13.1 years who quit 12.2 +/- 10.5 years prior to investigation) were studied. Patients wore a Caltrac accelerometer and a pedometer on each hip over two consecutive weekdays to assess free-living daily physical activity. Patients were also characterized on age, weight, body mass index (BMI), percent body fat, ankle/brachial index (ABI), calf blood flow, and exercise capacity. The smoking and nonsmoking claudication patients had a similar level of PAOD severity, for no group differences were noted in ABI (P=0.287) and treadmill time to maximal claudication pain (P=0.201). However, the smokers were 35% less physically active than the nonsmokers (264 +/- 123 vs 407 +/- 272 kcal/day; P<0.006), and they took 23% fewer steps (4,116 +/- 2,199 vs 5,329 +/- 2,924 steps/day; P<0.034). After adjustment for group differences in age, weight, BMI, percent body fat, and calf blood flow, the lower activity level of the smokers persisted. The adjusted daily energy expenditure was 27% lower (292 +/- 105 vs 400 +/- 214 kcal/day; P=0.021), and the adjusted amount of daily walking was 29% lower (4,039 +/- 1,760 vs 5,684 +/- 2,235 steps/day; P=0.003). Smoking PAOD patients had a less physically active lifestyle than nonsmoking patients, and the lower activity level of the smokers was independent of PAOD severity, age, body composition, and peripheral circulation.

Magnetic resonance angiography of the aortic arch.

Duplex ultrasound and magnetic resonance angiographic (MRA) studies are the principal noninvasive methods for evaluation of extracranial occlusive disease in patients at risk for stroke, but each has limited ability to diagnose aortic arch and arch vessel disease. Recent favorable reports of the nonnephrotoxic contrast agent Gadolinium (Gd) being used to enhance MRA images of the abdominal aorta prompted us to examine its utility for the aortic arch vessels. Prospectively, 28 patients with suspected carotid or arch vessel disease were imaged by contrast arteriographic examination and MRA + Gd of the aortic arch within 30 days of each other. One (for contrast arteriograms) or two (for MRA) blinded readers measured stenoses with the contrast arteriograms as the standard. A total of 196 arch vessels containing 58 stenoses and four occlusions (by arteriogram) were examined with each method. Interobserver agreement for interpretation of MRA studies was substantial (kappa = 0.68). MRA detected all anatomic anomalies (e.g., bovine arch). The correlation of MRA with arteriographic scans for arch vessel stenoses > 50% was sensitivity, 73% (readers 1 and 2); specificity, 98% (reader 1), 89% (reader 2); positive predictive value, 73% (reader 1), 89% (reader 2); negative predictive value, 98% (readers 1 and 2); accuracy, 97% (reader 1), 98% (reader 2). MRA + Gd is an accurate new noninvasive imaging method for detection of significant aortic arch disease. In its current state of development, however, it cannot obviate the need for contrast arteriographic examination.

The effect of cigarette smoking on exercise capacity in patients with intermittent claudication.

The purposes of this study were: (1) to determine whether peripheral arterial occlusive disease (PAOD) patients who smoked had more severe claudication pain, reduced peripheral circulation, and poorer cardiopulmonary measurements at peak exercise than non-smoking patients, and (2) to determine whether the differences between the smoking and non-smoking patients persisted after controlling for the resting ankle/brachial systolic pressure index (ABI). Thirty-eight PAOD patients (ABI = 0.59 +/- 0.15, mean +/- SD) who smoked an average of 1.5 packs of cigarettes per day over 42 years and 100 PAOD patients (ABI = 0.74 +/- 26) who had quit smoking for an average of 7 years were recruited. Smokers refrained from smoking on the day of testing. Claudication pain times, oxygen uptake, ventilation, leg oximetry, and ankle systolic pressure responses to peak exercise were recorded. The smoking group had more severe claudication pain, as maximal pain occurred 1:37 min:s sooner during exercise (p < 0.05), and the pain took 2:21 min:s longer to subside (p < 0.01) compared to the non-smoking group. Additionally, at peak exercise the smoking group had a lower oxygen uptake (12.8 +/- 2.6 vs 13.9 +/- 2.4 ml/kg/min, p < 0.01), a higher ventilation (31.7 +/- 9.2 vs 27.9 +/- 7.1 liters/min, p < 0.05), and a higher oximeter electrode power (409 +/- 55 vs 385 +/- 37 mW, p < 0.01) than the non-smoking group. Differences between the groups persisted (p < 0.05) after adjusting for resting ABI. It is concluded that cigarette smokers with PAOD had more severe claudication pain, reduced peripheral circulation, and poorer cardiopulmonary measurements at peak exercise than non-smoking patients. These differences were independent of resting ABI. Thus, cigarette smoking reduces the exercise capacity of claudicants, placing patients who smoke at an even greater risk of living a functionally dependent lifestyle.

Cardiac Evaluation of the Diabetic Patient Prior to Peripheral Vascular Surgery

The benefit of preoperative cardiac evaluation in the diabetic patient undergoing peripheral vascular surgery is uncertain. To investigate this issue we performed a retrospective review of 192 procedures performed in diabetic patients for chronic lower extremity arterial occlusive disease. The incidence of adverse postoperative cardiac events was determined, as well as its association with several preoperative factors including symptoms of coronary artery disease (CAD), extent and results of preoperative noninvasive cardiac evaluation, and operative site (aorta vs. lower extremity). The overall death and cardiac complication rates were 10.2% for lower extremity and 25.7% for aortic procedures (p = 0.02). For myocardial infarction and cardiac death alone, the rates were 5.1% and 5.7%, respectively (p > 0.10). Although a history of symptomatic CAD predicted the occurrence of any cardiac complication (28.3% vs. 8.2% [p < 0.01] for the aortic and lower extremity revascularization groups combined), no factor was found to be associated with the occurrence of myocardial infarction and cardiac death alone. In patients with a history of symptomatic CAD, there was no significant difference in the incidence of complications whether or not preoperative noninvasive cardiac testing was performed (28.1% vs. 28.6%, p > 0.10) or, if testing was performed, if the results were abnormal or normal (35.3% vs. 20.0%, p > 0.10). Similar results were obtained in patients with no history of symptomatic CAD. In summary, this retrospective review of our experience with noninvasive evaluation to detect CAD in diabetic patients undergoing peripheral vascular surgery failed to show any benefit in terms of reducing the incidence of postoperative cardiac events.

A PRACTICAL EQUATION TO PREDICT PEAK OXYGEN UPTAKE IN PATIENTS WITH INTERMITTENT CLAUDICATION 503

Measurement of peak oxygen uptake (VO2) in peripheral arterial occlusive disease (PAOD) patients is desirable because it gives an accurate estimate of functional capacity. However, not all facilities have access to the equipment necessary for its assessment. Thus, the ability to predict peak VO2 in a heterogeneous cohort of 206 PAOD patients (age = 69.1 ± 6.4 yrs; Mean ± SD) from resting and exercise measures was examined. Resting ankle/brachial systolic pressure index (ABI = 0.66 ± 0.23) in the more severely diseased leg, body mass index (BMI = 26.2 ± 4.1), and a medical history were taken prior to a progressive treadmill protocol (2 mph, 0% grade with 2% increase every 2 min). Maximal claudication pain time (MCPT = 411 ± 202 sec), maximal heart rate (MHR = 109 ± 18 b/min), and ABI immediately following exercise (0.30 ± 0.27) were recorded. Peak VO2 (13.1 ± 2.8 ml/kg/min) was predicted by MCPT, BMI, race(Caucasian = 1, African-American = 2), MHR, and gender (male = 1, female = 2) from the following regression equation: Peak VO2 (ml/kg/min) = 12.6 + (0.0071 × MCPT) - (1.7 × race) + (0.030 × MHR) - (0.096 × BMI) - (0.96 × gender); R = 0.68, R2 = 0.47, adjusted R2 = 0.46, SEE = 2.03, p < 0.0001. In conclusion, peak VO2 can be estimated to within ± 2 ml/kg/min in PAOD patients from readily obtained variables in clinical settings where its measurement is not routinely performed.