The effect of current cigarette smoking on calf muscle hemoglobin oxygen saturation in patients with intermittent claudication

Near infrared spectroscopy in peripheral artery disease and the diabetic foot: A systematic review

With the need for tools that assess microvascular status in diabetic foot disease (DFD) being clear, near infrared spectroscopy (NIRS) is a putative method for noninvasive testing of the diabetic foot. The use of NIRS in patients with peripheral arterial disease (PAD) has extended to its role in studying the pathophysiology of DFD. NIRS generates metrics such as recovery time, deoxygenation, oxygen consumption (VO₂ ), tissue oxygen saturation (StO₂ ), total haemoglobin (HbT), and oxyhaemoglobin area under the curve (O₂ Hb_AUC ). NIRS may potentially help the multidisciplinary team stratify limbs as high-risk, especially in diabetic patients with symptoms masked by peripheral neuropathy. NIRS may be useful for assessing treatment effectiveness and preventing deterioration of patients with PAD.

The long-term health effects of initiating smoking in adolescence: Evidence from a national longitudinal survey

We estimate the long-term effect of initiating smoking in adolescence on a range of health outcomes later in life. We use the second wave (1996) and the fifth wave (2016-2018) of the National Longitudinal Study of Adolescent to Adult Health (Add Health) and estimate instrumental variables models with school-level fixed effects, where the instruments are the average rate of smoking among friends and the respondents' perceptions about their friends' smoking. We find that smoking in adolescence has a negative impact on 15 of the 28 self-reported, diagnosed, and self-identified health outcomes approximately 20 years later.

Factors Associated With Change in Cardiovascular Fitness for Patients With Peripheral and Coronary Artery Disease in Cardiac Rehabilitation

PURPOSE

Cardiac rehabilitation (CR) yields improvements in cardiorespiratory fitness (peak oxygen uptake [V˙o2peak]). Predictors of change in V˙o2peak have been reported among patients with coronary artery disease (CAD) but have not been compared with peripheral artery disease (PAD). This study determined predictors of improved V˙o2peak among patients with PAD, CAD, and concomitant PAD and CAD (PAD/CAD) following a 6-mo home-based outpatient CR program (1supervised and 4 home weekly sessions).

METHODS

This study was a retrospective (2006-2017) multiple linear regression analysis of CR patients with PAD (n = 63), CAD (n = 63), and PAD/CAD (n = 164). Peripheral artery disease and CAD were matched for age, sex, smoking status, diabetes, and year in program.

RESULTS

Mean age of all patients was 68.9±10.1 yr, 72% were male, and mean improvement in V˙o2peak was 2.1 ± 3.3 mL/kg/min (14.5% improvement) following CR. In CAD, younger age (β = .30, P = .015), male sex (β = -.29, P = .019), and more recent year of entry (β = .26, P = .035) were predictors of improved V˙o2peak. In PAD, only male sex (β = -.36, P = .004) and in PAD/CAD, not having diabetes (β = -.24, P = .002), not smoking (β = -.25, P = .001), and shorter elapsed time from referring diagnosis to entry (β = -.19, P = .016) were predictors.

CONCLUSIONS

While younger age and male sex were predictors of improved V˙o2peak in CAD, age did not influence PAD, and neither age nor sex influenced PAD/CAD. Peripheral artery disease-related limitations may override some demographic factors, and strategies for improving V˙o2peak should be explored. Managing smoking and comorbid diagnoses including diabetes and a timely entry to CR may yield greater improvements in V˙o2peak among individuals with PAD.

Physical activity and risk of bladder cancer among postmenopausal women

Physical activity is associated with decreased risk for many cancers. Studies on the association between physical activity and risk of bladder cancer are limited, and findings are inconsistent. Postmenopausal women (mean age = 63.3) were recruited into the Women's Health Initiative from 1993 to 1998. Self-reported baseline information on physical activity and other covariates were available in 141 288 participants. Incident bladder cancer cases were collected through 2018 and centrally adjudicated. Hazard ratios (HRs) and 95% confidence intervals (CIs) were determined by Cox proportional hazard regression models. Effect modification due to smoking was assessed. During an average of 18.5 years of follow-up, 817 bladder cancer cases were identified. Compared to physically inactive women, those who engaged in ≥15 MET-hours/week of total physical activity, ≥8.75 MET-hours/week of walking or ≥11.25 MET-hours/week of moderate to vigorous physical activity had lower risk of bladder cancer (HR = 0.74, 95% CI: 0.59-0.94, P for linear trend = .02; HR = 0.79, 95% CI: 0.63-0.98, P for linear trend = .03; and HR = 0.76, 95% CI: 0.61-0.94, P for linear trend = .02, respectively). No effect modification was found by smoking status (P for interaction = .06, 0.91 and 0.27, respectively). We found that total physical activity, walking and moderate to vigorous physical activity were inversely associated with bladder cancer incidence among postmenopausal women in a dose-response manner. Physical activity may play a potential role in the primary prevention of bladder cancer. Further studies with objective measurements of physical activity are needed to confirm these findings.

Association between calf muscle oxygen saturation with ambulatory function and quality of life in symptomatic patients with peripheral artery disease

OBJECTIVE

The objective of this study was to determine whether calf muscle hemoglobin oxygen saturation (Sto₂) obtained during a standardized treadmill test is associated with ambulatory function and health-related quality of life (HRQoL) in patients with symptomatic peripheral artery disease (PAD). We hypothesized that a rapid decline in calf muscle Sto₂ during walking is associated with impaired ambulatory function and HRQoL and that these associations are independent of ankle-brachial index (ABI).

METHODS

Calf muscle Sto₂, peak walking time, and claudication onset time were obtained during a treadmill test in 151 symptomatic men and women with PAD. Patients were further characterized by demographic variables, comorbid conditions, cardiovascular risk factors, ABI, 6-minute walk distance, daily ambulatory activity, Walking Impairment Questionnaire (WIQ) score, and Medical Outcomes Study 36-Item Short Form Health Survey physical function score to assess HRQoL.

RESULTS

The median calf muscle Sto₂ value at rest was 52%, which declined to 22% after only 1 minute of walking during the treadmill test and reached a minimum value of 9% after a median time of 87 seconds of walking. Of the various calf muscle Sto₂ measurements obtained during the treadmill test, the exercise time to the minimum calf muscle Sto₂ value (log transformed) had the strongest univariate associations with peak walking time (r = 0.56; P < .001), claudication onset time (r = 0.49; P < .001), 6-minute walk distance (r = 0.31; P < .001), WIQ distance score (r = 0.33; P < .001), WIQ speed score (r = 0.39; P < .001), WIQ stair-climbing score (r = 0.37; P < .001), and Medical Outcomes Study 36-Item Short Form Health Survey physical function score (r = 0.32; P < .001). In adjusted multiple regression models, these associations persisted (P < .001) after adjustment for demographic measures, cardiovascular risk factors, comorbid conditions, and ABI.

CONCLUSIONS

More rapid decline in oxygen saturation of the calf musculature during walking, indicative of impaired microcirculation, is predictive of impaired ambulatory function and HRQoL in patients with symptomatic PAD. Of particular importance, these associations are independent of ABI and other common health burdens, highlighting the clinical relevance that the microcirculation has on ambulatory function and HRQoL in patients with symptomatic PAD.

A low-cost, wireless near-infrared spectroscopy device detects the presence of lower extremity atherosclerosis as measured by computed tomographic angiography and characterizes walking impairment in peripheral artery disease

BACKGROUND

Patients with peripheral artery disease (PAD) who experience intermittent claudication report a range of symptoms. Patients with symptoms other than classically described intermittent claudication may be at the highest risk for functional decline and mobility loss. Therefore, technologies allowing for characterization of PAD severity are desirable. Near-infrared spectroscopy (NIRS) allows for measurements of muscle heme oxygen saturation (StO₂) during exercise. We hypothesized lower extremities affected by PAD would exhibit distinct NIRS profiles as measured by a low-cost, wireless NIRS device and that NIRS during exercise predicts walking limitation.

METHODS

We recruited 40 patients with PAD and 10 control participants. All patients with PAD completed a computed tomographic angiography, 6-minute walk test, and a standardized treadmill test. Controls completed a 540-second treadmill test for comparison. StO₂ measurements were continuously taken from the gastrocnemius during exercise. Variables were analyzed by Fischer's exact, χ², Wilcoxon rank-sum, and Kruskal-Wallis tests as appropriate. Correlations were assessed by partial Spearman correlation coefficients adjusted for occlusive disease pattern.

RESULTS

Patients with PAD experienced claudication onset at a median of 108 seconds with a median peak walking time of 288 seconds. The baseline StO₂ was similar between PAD and control. The StO₂ of PAD and control participants dropped below baseline at a median of 1 and 104 seconds of exercise, respectively (P < .0001). Patients with PAD reached minimum StO₂ earlier than control participants (119 seconds vs 522 seconds, respectively; P < .001) and experienced a greater change in StO₂ at 1 minute of exercise (-73.2% vs 8.3%; P < .0001) and a greater decrease at minimum exercise StO₂ (-83.4% vs -16.1%; P < .0001). For patients with PAD, peak walking time, and 6-minute walking distance correlated with percent change in StO₂ at 1 minute of exercise (r = -0.76 and -0.67, respectively; P < .001) and time to minimum StO₂ (r = 0.79 and 0.70, respectively; P < .0001).

CONCLUSIONS

In this initial evaluation of a novel, low-cost NIRS device, lower extremities affected by PAD exhibited characteristic changes in calf muscle StO₂, which differentiated them from healthy controls and were strongly correlated with walking impairment. These findings confirm and expand on previous work demonstrating the potential clinical value of NIRS devices and the need for further research investigating the ability of low-cost NIRS technology to evaluate, diagnose, and monitor treatment response in PAD.

Influence of smoking on physical function, physical activity, and cardiovascular health parameters in patients with symptomatic peripheral arterial disease: A cross-sectional study

The aim of this study was to analyze the impact of smoking on physical activity, walking capacity, and cardiovascular health in patients with symptomatic peripheral arterial disease (PAD). This cross-sectional study included 180 patients with symptomatic PAD. Patients were classified into 3 groups according to smoking history: smoker (n = 39), ex-smoker (n = 113), and never smoker (n = 28). Physical activity levels, physical function, walking capacity, and cardiovascular health parameters (clinical blood pressure, arterial stiffness, and heart rate variability) were assessed. Smoker patients presented higher sympathetic modulation to the heart (low frequency of heart rate variability: smokers, 71 ± 17 nu; ex-smokers, 53 ± 32 nu; never smokers, 49 ± 21 nu, P < .05) and sympathovagal balance (smokers: 2.44 ± 2.76, ex-smokers: 1.14 ± 1.74, never smokers: 1.04 ± 0.99, P < .05) and lower parasympathetic modulation to the heart (high frequency of heart rate variability: smokers, 29 ± 27 nu; ex-smokers, 47 ± 32 nu; never smokers, 51 ± 21 nu, P < .05) than other patients. In conclusion, nonsignificant differences were observed on physical activity levels, physical function, blood pressure, and arterial stiffness (P > .05). Smoking impairs cardiac autonomic modulation in patients with symptomatic PAD.

Interaction of p-benzoquinone with hemoglobin in smoker's blood causes alteration of structure and loss of oxygen binding capacity

Cigarette smoke (CS) is an important source of morbidity and early mortality worldwide. Besides causing various life-threatening diseases, CS is also known to cause hypoxia. Chronic hypoxia would induce early aging and premature death. Continuation of smoking during pregnancy is a known risk for the unborn child. Although carbon monoxide (CO) is considered to be a cause of hypoxia, the effect of other component(s) of CS on hypoxia is not known. Here we show by immunoblots and mass spectra analyses that in smoker's blood p-benzoquinone (p-BQ) derived from CS forms covalent adducts with cysteine 93 residues in both the β chains of hemoglobin (Hb) producing Hb-p-BQ adducts. UV-vis spectra and CD spectra analyses show that upon complexation with p-BQ the structure of Hb is altered. Compared to nonsmoker's Hb, the content of α-helix decreased significantly in smoker's Hb (p = 0.0224). p-BQ also induces aggregation of smoker's Hb as demonstrated by SDS-PAGE, dynamic light scattering and atomic force microscopy. Alteration of Hb structure in smoker's blood is accompanied by reduced oxygen binding capacity. Our results provide the first proof that p-BQ is a cause of hypoxia in smokers. We also show that although both p-BQ and CO are responsible for causing hypoxia in smokers, exposure to CO further affects the function over and above that produced by Hb-p-BQ adduct.

Patient Characteristics and Comorbidities Influence Walking Distances in Symptomatic Peripheral Arterial Disease: A Large One-Year Physiotherapy Cohort Study

Objectives

The aim of this study is to investigate the association between age, gender, body-mass index, smoking behavior, orthopedic comorbidity, neurologic comorbidity, cardiac comorbidity, vascular comorbidity, pulmonic comorbidity, internal comorbidity and Initial Claudication Distance during and after Supervised Exercise Therapy at 1, 3, 6 and 12 months in a large sample of patients with Intermittent Claudication.

Methods

Data was prospectively collected in standard physiotherapy care. Patients received Supervised Exercise Therapy according to the guideline Intermittent Claudication of the Royal Dutch Society for Physiotherapy. Three-level mixed linear regression analysis was carried out to analyze the association between patient characteristics, comorbidities and Initial Claudication Distance at 1, 3, 6 and 12 months.

Results

Data from 2995 patients was analyzed. Results showed that being female, advanced age and a high body-mass index were associated with lower Initial Claudication Distance at all-time points (p = 0.000). Besides, a negative association between cardiac comorbidity and Initial Claudication Distance was revealed (p = 0.011). The interaction time by age, time by body-mass index and time by vascular comorbidity were significantly associated with Initial Claudication Distance (p≤ 0.05). Per year increase in age (range: 33–93 years), the reduction in Initial Claudication Distance was 8m after 12 months of Supervised Exercise Therapy. One unit increase in body-mass index (range: 16–44 kg/m²) led to 10m less improvement in Initial Claudication Distance after 12 months and for vascular comorbidity the reduction in improvement was 85m after 12 months.

Conclusions

This study reveals that females, patients at advanced age, patients with a high body-mass index and cardiac comorbidity are more likely to show less improvement in Initial Claudication Distances (ICD) after 1, 3, 6 and 12 months of Supervised Exercise Therapy. Further research should elucidate treatment adaptations that optimize treatment outcomes for these subgroups.

The effects of smoking status on walking ability and health-related quality of life in patients with peripheral arterial disease

BACKGROUND

Smoking is a leading risk factor for peripheral arterial disease (PAD), yet little is known about the interrelationships among smoking status, walking endurance, calf muscle tissue oxygenation, and quality of life in patients with PAD.

OBJECTIVE

The aim of this study was to explore the differences in factors associated with walking endurance including walk distance, perceived walking ability, measures of skeletal muscle tissue oxygenation (StO2), claudication pain, peak oxygen consumption per unit time, and quality of life in smokers versus nonsmokers.

METHODS

A total of 105 patients with PAD performed progressive, symptom-limited treadmill test. Ankle-brachial index was measured at baseline. Calf muscle tissue oxygenation measures were obtained during testing. The RAND Short Form-36 and Walking Impairment Questionnaire were used to measure health-related quality of life (HR-QoL).

RESULTS

In the total sample (36 current smokers, 69 nonsmokers), smokers had steeper declines in StO2 from baseline to 2 minutes (42.3% vs 33%, P = .05) and shorter distance walked to onset of claudication pain (142.6 vs 247.7 m) than did nonsmokers (P < .0125), despite having no differences in ankle-brachial index, peak oxygen consumption per unit time, or any momentary measure of StO2 during walking. Smokers reported significantly lower HR-QoL on the Short Form-36 in several domains but no differences in the Walking Impairment Questionnaire measures. The smokers were younger than the nonsmokers; however, when age was entered as a covariate in the analyses, the results remained unchanged.

CONCLUSIONS

These findings suggest that smokers have lower HR-QoL than do nonsmokers with PAD and that smoking confers risks for disrupted tissue oxygenation above those seen in patients who do not smoke.

Textile integrated sensors and actuators for near-infrared spectroscopy

Being the closest layer to our body, textiles provide an ideal platform for integrating sensors and actuators to monitor physiological signals. We used a woven textile to integrate photodiodes and light emitting diodes. LEDs and photodiodes enable near-infrared spectroscopy (NIRS) systems to monitor arterial oxygen saturation and oxygenated and deoxygenated hemoglobin in human tissue. Photodiodes and LEDs are mounted on flexible plastic strips with widths of 4 mm and 2 mm, respectively. The strips are woven during the textile fabrication process in weft direction and interconnected with copper wires with a diameter of 71 μm in warp direction. The sensor textile is applied to measure the pulse waves in the fingertip and the changes in oxygenated and deoxygenated hemoglobin during a venous occlusion at the calf. The system has a signal-to-noise ratio of more than 70 dB and a system drift of 0.37% ± 0.48%. The presented work demonstrates the feasibility of integrating photodiodes and LEDs into woven textiles, a step towards wearable health monitoring devices.

Exercise training and peripheral arterial disease

Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.

Clinical significance of ankle systolic blood pressure following exercise in assessing calf muscle tissue ischemia in peripheral artery disease

Our primary objective assessed whether a decline in ankle systolic blood pressure (SBP) to less than 50 mm Hg after treadmill exercise is associated with lower extremity ischemia, as measured by calf muscle hemoglobin oxygen saturation (StO(2)). Eighty-four patients with peripheral artery disease (PAD) completed a treadmill test. Ankle SBP <50 mm Hg following exercise was observed in only 49% (group 1), whereas 51% had ankle SBP ≥50 mm Hg (group 2). No group differences were observed for the decline in calf muscle StO(2) to a minimum value (group 1: 18 ± 21%, group 2: 20 ± 20%; P = .60) and for the time to reach minimum StO(2) (group 1: 224 ± 251 seconds, group 2: 284 ± 283 seconds; P = .30). Requirement of ankle SBP to decrease below 50 mm Hg after exercise has little clinical significance for assessing ischemia in calf muscle of patients with PAD limited by intermittent claudication.

Calf muscle hemoglobin oxygen saturation in patients with peripheral artery disease who have different types of exertional leg pain

BACKGROUND

This study compared calf muscle hemoglobin oxygen saturation (Sto(2)) and exercise performance during standardized treadmill exercise in patients with peripheral artery disease (PAD) who describe different types of exertional leg pain and compared secondary outcomes consisting of daily ambulatory activity and exercise performance during a 6-minute walk test (6MWT).

METHODS

Leg pain symptoms were evaluated in 114 patients with PAD using the San Diego Claudication Questionnaire, by which atypical exertional leg pain was defined in 31, claudication in 37, and leg pain on exertion and rest in 46. Patients were evaluated on a standardized, graded treadmill test during which calf muscle Sto(2) was continuously monitored. The 6MWT distance, Walking Impairment Questionnaire (WIQ), and ambulatory activity were monitored during 1 week.

RESULTS

All patients experienced symptoms during the treadmill test consistent with claudication. The groups were not significantly different on the primary outcomes of time to reach the minimum calf muscle Sto(2) (P = .350) or peak walking time (P = .238) during treadmill exercise. Patients with atypical leg pain had the highest daily ambulatory activity for total strides per day (P = .032), average daily cadence (P = .010), maximum cadences for durations between 5 minutes (P = .035) and 60 minutes (P = .029), speed score on the WIQ (P = .006), and lowest rating of perceived exertion at the end of the 6MWT (P = .017).

CONCLUSIONS

PAD patients with atypical leg pain have vascular-mediated limitations in exercise performance during standardized treadmill testing similar to patients with claudication and patients with leg pain on exertion and rest but have higher levels of daily ambulatory activity in the community setting and higher perceived ambulatory function.

Gender differences in daily ambulatory activity patterns in patients with intermittent claudication

OBJECTIVES

To compare the pattern of daily ambulatory activity in men and women with intermittent claudication, and to determine whether calf muscle hemoglobin oxygen saturation (StO2) is associated with daily ambulatory activity.

METHODS

Forty men and 41 women with peripheral arterial disease limited by intermittent claudication were assessed on their community-based ambulatory activity patterns for 1 week with an ankle-mounted step activity monitor and on calf muscle StO2 during a treadmill test.

RESULTS

Women had lower adjusted daily maximal cadence (mean±SE) for 5 continuous minutes of ambulation (26.2±1.2 strides/min vs 31.0±1.2 strides/min; P=.009), for 1 minute of ambulation (43.1±0.9 strides/min vs 47.2±0.9 strides/min; P=.004), and for intermittent ambulation determined by the peak activity index (26.3±1.2 strides/min vs 31.0±1.2 strides/min; P=.009). Women also had lower adjusted time to minimum calf muscle StO2 during exercise (P=.048), which was positively associated with maximal cadence for 5 continuous minutes (r=0.51; P<.01), maximal cadence for 1 minute (r=0.42; P<.05), and peak activity index (r=0.44; P<.05). These associations were not significant in men.

CONCLUSION

Women with intermittent claudication ambulate slower in the community setting than men, particularly for short continuous durations of up to 5 minutes and during intermittent ambulation at peak cadences. Furthermore, the daily ambulatory cadences of women are correlated with their calf muscle StO2 during exercise, as women who walk slower in the community setting reach their minimum calf muscle StO2 sooner than those who walk at faster paces. Women with intermittent claudication should be encouraged to not only walk more on a daily basis, but to do so at a pace that is faster than their preferred speed.

Limb-specific and cross-transfer effects of arm-crank exercise training in patients with symptomatic peripheral arterial disease

Arm cranking is a useful alternative exercise modality for improving walking performance in patients with intermittent claudication; however, the mechanisms of such an improvement are poorly understood. The main aim of the present study was to investigate the effects of arm-crank exercise training on lower-limb O2 delivery in patients with intermittent claudication. A total of 57 patients with intermittent claudication (age, 70±8 years; mean±S.D.) were randomized to an arm-crank exercise group or a non-exercise control group. The exercise group trained twice weekly for 12 weeks. At baseline and 12 weeks, patients completed incremental tests to maximum exercise tolerance on both an arm-crank ergometer and a treadmill. Respiratory variables were measured breath-by-breath to determine peak V̇O2 (O2 uptake) and ventilatory threshold. Near-IR spectroscopy was used in the treadmill test to determine changes in calf muscle StO2 (tissue O2 saturation). Patients also completed a square-wave treadmill-walking protocol to determine V̇O2 kinetics. A total of 51 patients completed the study. In the exercise group, higher maximum walking distances (from 496±250 to 661±324 m) and peak V̇O2 values (from 17.2±2.7 to 18.2±3.4 ml·kg−1 of body mass·min−1) were recorded in the incremental treadmill test (P<0.05). After training, there was also an increase in time to minimum StO2 (from 268±305 s to 410±366 s), a speeding of V̇O2 kinetics (from 44.7±10.4 to 41.3±14.4 s) and an increase in submaximal StO2 during treadmill walking (P<0.05). There were no significant changes in the control group. The results suggest that the improvement in walking performance after arm-crank exercise training in patients with intermittent claudication is attributable, at least in part, to improved lower-limb O2 delivery.

Sex differences in calf muscle hemoglobin oxygen saturation in patients with intermittent claudication

PURPOSES

We tested the hypotheses that women have greater impairment in calf muscle hemoglobin oxygen saturation (StO(2)) in response to exercise than men, and that the sex-related difference in calf muscle StO(2) would partially explain the shorter claudication distances of women.

METHODS

The study comprised 27 men and 24 women with peripheral arterial disease limited by intermittent claudication. Patients were characterized on calf muscle StO(2) before, during, and after a graded treadmill test, as well as on demographic and cardiovascular risk factors, ankle-brachial index (ABI), ischemic window, initial claudication distance (ICD), and absolute claudication distance (ACD).

RESULTS

Women had a 45% lower ACD than men (296 +/- 268 m vs 539 +/- 288 m; P = .001) during the treadmill test. Calf muscle StO(2) declined more rapidly during exercise in women than in men; the time to reach minimum StO(2) occurred 54% sooner in women (226 +/- 241 vs 491 +/- 426 seconds; P = .010). The recovery time for calf muscle StO(2) to reach the resting value after treadmill exercise was prolonged in women (383 +/- 365 vs 201 +/- 206 seconds; P = .036). Predictors of ACD included the time from start of exercise to minimum calf muscle StO(2), the average rate of decline in StO(2) from rest to minimum StO(2) value, the recovery half-time of StO(2), and ABI (R(2) = 0.70; P < .001). The ACD of women remained lower after adjusting for ABI (mean difference, 209 m; P = .003), but was no longer significantly lower (mean difference, 72 m; P = .132) after further adjustment for the StO(2) variables for the three calf muscles.

CONCLUSION

In patients limited by intermittent claudication, women have lower ACD and greater impairment in calf muscle StO(2) during and after exercise than men, the exercise-mediated changes in calf muscle StO(2) are predictive of ACD, and women have similar ACD as men after adjusting for calf StO(2) and ABI measures.

The Physiological Effects of Short-term Smoking Cessation in Claudicants

Introduction

Smoking contributes to atherosclerosis and causes significant postoperative morbidity. New antismoking law forces short-term pre-operative abstinence. Demonstrable clinical benefit might motivate complete cessation. Our aim was to determine the effects of 24-hr smoking cessation on cardiorespiratory function and claudication distance.

Methods

Smoking claudicants were randomized to 24hr smoking or abstinence. Following these separate periods, cardiopulmonary exercise testing was performed. Pre- and post-exercise, serum lactate and ankle brachial pressure index (ABPI) were measured. During exercise, cardiorespiratory function, initial and absolute claudication (IC, AC) distances and visual analogue scores (VAS) of pain were recorded.

Results

16 patients completed both tests. IC, AC and VAS were unchanged with abstinence ( P = .43, .66, .96, .83). ABPI drop post-exercise was unchanged with abstinence ( P = .08, .09). Cardiorespiratory function was not affected by smoking cessation.

Conclusion

Cardiorespiratory function and claudication symptoms are unchanged following 24-hr smoking cessation., No deterioration in respiratory function is important when considering anaesthetic administration. However, lack of symptomatic improvement may discourage patients from abstaining. Further investigation should determine correlation between short-term abstinence and postoperative morbidity.

Calf muscle hemoglobin oxygen saturation characteristics and exercise performance in patients with intermittent claudication

PURPOSE

This study was conducted to determine the association between the characteristics of calf muscle hemoglobin oxygen saturation (StO(2)) and exercise performance in patients with intermittent claudication.

METHODS

The study comprised 39 patients with peripheral arterial disease limited by intermittent claudication. Patients were characterized on calf muscle StO(2) before, during, and after a graded treadmill test, as well as on demographic and cardiovascular risk factors, ankle-brachial index (ABI), ischemic window, initial claudication distance (ICD), and absolute claudication distance (ACD).

RESULTS

Calf muscle StO(2) decreased 72%, from 55% +/- 18% (mean +/- SD) saturation at rest to the minimum value of 17% +/- 19% saturation attained 459 +/- 380 seconds after the initiation of exercise. After exercise, recovery half-time of calf muscle StO(2) was attained at 129 +/- 98 seconds, whereas full recovery to the resting value was reached at 225 +/- 140 seconds. After adjusting for sex, race, and grouping according to the initial decline constant in calf muscle StO(2) during exercise, the exercise time to minimum calf muscle StO(2) was correlated with the ischemic window (r = -0.493, P = .002), ICD (r = 0.339, P = .043), and ACD (r = 0.680, P < .001). After treadmill exercise, the recovery half-time of calf muscle StO(2) was correlated with the ischemic window (r = 0.531, P < .001), ICD (r = -0.598, P < .001), and ACD (r = -0.491, P = .003).

CONCLUSION

In patients limited by intermittent claudication, shorter ICD and ACD values are associated with reaching a minimum value in calf muscle StO(2) sooner during treadmill exercise and with having a delayed recovery in calf muscle StO(2) after exercise.