Interventions to Improve Medication Adherence in Ethnically Diverse Patients: A Narrative Systematic Review

INTRODUCTION

Ethnically diverse patients often have lower medication adherence relative to Whites. Certain ethnic groups are also more susceptible to cardiovascular and related diseases. It is critical to develop culturally tailored interventions to improve medication adherence in these ethnically diverse patients. Thus, the aim of this systematic review was to identify what interventions have been developed and tested to improve medication adherence in ethnically diverse patients with cardiovascular-related diseases.

METHOD

A systematic search of peer-reviewed literature (MEDLINE, Cumulative Index to Nursing and Allied Health Literature, EMBASE, and Cochrane Central Register of Controlled Trials) was conducted to identify relevant articles. The narrative synthesis was performed based on elements offered by Popay et al. The mixed methods appraisal tool was used to appraise the quality of the included studies.

RESULTS

A total of 11,294 records were retrieved, and 34 articles met the inclusion criteria for this systematic review. Synthesis of the literature revealed four overarching intervention strategies used to improve medication adherence: pharmacist-mediated, primarily nurse-led, community-based and community-health worker led, and text-message and phone-based.

DISCUSSION

Several approaches can be used to improve medication adherence in ethnically diverse patients, although details on the approaches and conditions to produce optimal improvements for particular ethnic groups need to be determined in future studies. How does this affect culturally congruent health care?

Development of a Culturally Tailored Motivational Interviewing-Based Intervention to Improve Medication Adherence in South Asian Patients

BACKGROUND

South Asians (SAs) are among the fastest growing ethnic population in Western countries and have a higher risk of cardiovascular diseases relative to the general population. SAs living in Canada also have poorer adherence to medical regimens for treating cardiovascular disease, relative to other ethnic groups. Motivational interviewing (MI) maybe effective in improving health-related behaviour change in patients; however, the research is nascent on the effectiveness of MI in SAs and may also require cultural adaptation.

AIM

To develop a culturally tailored MI-based intervention to improve medication adherence in hypertensive SA patients living in Canada.

METHODS

Previous literature about medication adherence in SAs was reviewed, along with transcripts and responses to open-ended survey questions from our previous studies with SAs, to draft an MI intervention manual. The manual received extensive feedback from the study team, SA community members and health-care providers who work with SA patients. The feedback was used to refine the manual and make it culturally tailored and relevant to SA hypertensive patients living in Canada.

RESULTS

A culturally tailored MI-based manual which we called a "motivational communication manual" was developed to support a study focused on improving medication adherence in SA hypertensive patients. The development process, components (eg, being culturally sensitive, family involvement, providing education about medications, reminders, etc.) and cultural nuances included in the manual are described in this paper.

CONCLUSION

This is the first culturally tailored MI-based intervention manual that has been developed with the aim of improving medication adherence in hypertensive SA patients and that includes direct feedback from SA community members. Use of this manual may improve the accessibility and adoption of MI-based practices in improving health behaviours in SAs living in Canada as well as encourage further research studies and clinical trials with SA patients.

Effects of High-Intensity Interval Running Versus Cycling on Sclerostin, and Markers of Bone Turnover and Oxidative Stress in Young Men

This study compared sclerostin's response to impact versus no-impact high-intensity interval exercise in young men and examined the association between exercise-induced changes in sclerostin and markers of bone turnover and oxidative stress. Twenty healthy men (22.3 ± 2.3 years) performed two high-intensity interval exercise trials (crossover design); running on treadmill and cycling on cycle ergometer. Trials consisted of eight 1 min running or cycling intervals at ≥ 90% of maximal heart rate, separated by 1 min passive recovery intervals. Blood samples were collected at rest (pre-exercise), and 5 min, 1 h, 24 h, and 48 h following each trial. Serum levels of sclerostin, cross-linked telopeptide of type I collagen (CTXI), procollagen type I amino-terminal propeptide (PINP), thiobarbituric acid reactive substances (TBARS), and protein carbonyls (PC) were measured. There was no significant time or exercise mode effect for PINP and PC. A significant time effect was found for sclerostin, CTXI, and TBARS with no significant exercise mode effect and no significant time-by-mode interaction. Sclerostin increased from pre- to 5 min post-exercise (47%, p < 0.05) and returned to baseline within 1 h following the exercise. CTXI increased from pre- to 5 min post-exercise (28%, p < 0.05), then gradually returned to baseline by 48 h. TBARS did not increase significantly from pre- to 5 min post-exercise but significantly decreased from 5 min to 48 h post-exercise. There were no significant correlations between exercise-induced changes in sclerostin and any other marker. In young men, sclerostin's response to high-intensity interval exercise is independent of impact and is not related to changes in bone turnover and oxidative stress markers.

South Asians' experience of managing hypertension: a grounded theory study

OBJECTIVE

We examined the process that South Asians undergo when managing their hypertension (HTN).

METHOD

Using grounded theory methods, 27 community-dwelling English-, Punjabi-, or Hindi-speaking South Asian participants (12 men and 15 women), who self-identified as having HTN were interviewed. Transcripts were analyzed using constant comparison.

RESULTS

The core category was "fitting it in". First, the participants assessed their diagnosis and treatment primarily in the context of their current family/social environment. Participants who paid attention to their diagnosis either fully or partly embraced activities and attitudes associated with successful management of hypertension. However, those who did not attend to their diagnosis, identified other familial/social factors, stress of immigration, and not having symptoms of their disease as barriers. The longer the time since diagnosis of HTN, the more participants came to appropriately manage their HTN.

CONCLUSION

Healthcare providers may use this information to enhance their cultural understanding of how and why South Asians manage their HTN.

Understanding ethno-cultural differences in cardiac medication adherence behavior: a Canadian study

BACKGROUND

There are ethno-cultural differences in cardiac patients' adherence to medications. It is unclear why this occurs. We thus aimed to generate an in-depth understanding about the decision-making process and potential ethno-cultural differences, of white, Chinese, and south Asian cardiac patients when making the decision to adhere to a medication regimen.

METHODS

A hierarchical descriptive decision-model was generated based on previous qualitative work, pilot tested, and revised to be more parsimonious. The final model was examined using a novel group of 286 cardiac patients, using their self-reported adherence as the reference. Thereafter, each node was examined to identify decision-making constructs that might be more applicable to white, Chinese or south Asian groups.

RESULTS

Non-adherent south Asians were most likely to identify a lack of receipt of detailed medication information, and less confidence and trust in the health care system and health care professionals. Both Chinese and south Asian participants were less likely to be adherent when they had doubts about western medicine (eg, the effects and safety of the medication). Being able to afford the cost of medications was associated with increased adherence. Being away from home reduced the likelihood of adherence in each group. The overall model had 67.1% concordance with the participants' initial self-reported adherence, largely due to participants' overreporting adherence.

CONCLUSION

These identified elements of the decision-making process are generally not considered in traditionally used medication adherence questionnaires. Importantly these elements are modifiable and ought to be the focus of both interventions and measurement of medication adherence.

Ethno-Cultural Considerations in Cardiac Patients’ Medication Adherence

We aimed to develop an in-depth understanding about factors that influence cardiac medication adherence among South Asian, Chinese, and European White cardiac patients. Sixty-four patients were purposively sampled from an ongoing study cohort. Interviews were audio-recorded and transcribed for analyses. Physicians’ culturally sensitive communication and patients’ motivation to live a symptom-free and longer life enhanced adherence. European Whites were motivated to enhance personal well-being and enjoy family life. South Asians’ medication adherence was influenced by the desire to fulfill the will of God and family responsibilities. The Chinese were motivated to avoid pain, illness, and death, and to obey a health care provider. The South Asians and Chinese wanted to ultimately reduce medication use. Previous positive experiences, family support, and establishing a routine also influenced medication adherence. Deterrents to adherence were essentially the reverse of the motivators/facilitators. This analysis represents an essential first step forward in developing ethno-culturally tailored interventions to optimize adherence.

The Role of Adverse Event Reporting in the FDA Response to a Multistate Outbreak of Liver Disease Associated with a Dietary Supplement

OBJECTIVE

Liver disease is a potential complication from using dietary supplements. This study investigated an outbreak of non-viral liver disease associated with the use of OxyELITE Pro(TM), a dietary supplement used for weight loss and/or muscle building.

METHODS

Illness details were ascertained from MedWatch reports submitted to the U.S. Food and Drug Administration (FDA) describing consumers who ingested OxyELITE Pro alone or in combination with other dietary supplements. FDA's Forensic Chemistry Center analyzed samples of OxyELITE Pro.

RESULTS

From February 2012 to February 2014, FDA received 114 reports of adverse events of all kinds involving consumers who ingested OxyELITE Pro. The onset of illness for the first report was December 2010 and for the last report was January 2014. Thirty-three states, two foreign nations, and Puerto Rico submitted reports. Fifty-five of the reports (48%) described liver disease in the absence of viral infection, gallbladder disease, autoimmune disease, or other known causes of liver damage. A total of 33 (60%) of these patients were hospitalized, and three underwent liver transplantation. In early 2013, OxyELITE Pro products entered the market with a formulation distinct from products sold previously. The new formulation replaced 1,3-dimethylamylamine with aegeline. However, the manufacturer failed to submit to FDA a required "new dietary ingredient" notice for the use of aegeline in OxyELITE Pro products. Laboratory analysis identified no drugs, poisons, pharmaceuticals, toxic metals, usnic acid, N-Nitroso-fenfluramine, pyrrolizidine alkaloids, aristocholic acid, or phenethylamines in the products.

CONCLUSIONS

Vigilant surveillance is required for adverse events linked to the use of dietary supplements.

The influence of ethnicity and gender on navigating an acute coronary syndrome event

BACKGROUND

Ethnicity and gender may influence acute coronary syndrome patients recognizing symptoms and making the decision to seek care.

OBJECTIVE

To examine these potential differences in European (Caucasian), Chinese and South Asian acute coronary syndrome patients.

METHODS

In-depth interviews were conducted with 20 European (Caucasian: 10 men/10 women), 18 Chinese (10 men/eight women) and 19 South Asian (10 men/nine women) participants who were purposively sampled from those participating in a large cohort study focused on acute coronary syndrome. Analysis of transcribed interviews was undertaken using constant comparative methods.

RESULTS

Participants followed the process of: having symptoms; waiting/denying; justifying; disclosing/ discovering; acquiescing; taking action. The core category was 'navigating the experience'. Certain elements of this process were in the forefront, depending on participants' ethnicity and/or gender. For example, concerns regarding language barriers and being a burden to others varied by ethnicity. Women's tendency to feel responsibility to their home and family negatively impacted the timeliness in their decisions to seek care. Men tended to disclose their symptoms to receive help, whereas women often waited for their symptoms to be discovered by others. Finally, the thinking that symptoms were 'not-urgent' or something over which they had no control and concern regarding potential costs to others were more prominent for Chinese and South Asian participants.

CONCLUSION

Ethnic- and gender-based differences suggest that education and support, regarding navigation of acute coronary syndrome and access to care, be specifically targeted to ethnic communities.

Understanding the influence of urban- or rural-living on cardiac patients' decisions about diet and physical activity: descriptive decision modeling

BACKGROUND

It is challenging to assist people to attend to risk factors for coronary artery disease (CAD). There is potential for cultural elements associated with place of residence (i.e., urban- or rural-living) to have an effect on peoples' decision-making about managing CAD risk.

AIM

To better understand patient's decision-making processes regarding having a heart-healthy diet and engaging in regular physical activity (major CAD risk factors), and the potential influence of urban- or rural-living.

METHODS

Based on a previous series of qualitative interviews with 42 cardiac patients (21 urban-living, 21 rural-living), hierarchical decision-models regarding eating a heart-healthy diet and engaging in regular physical activity were developed, and a survey based on the decision-models generated. The models were then tested for 'fit' with another group of 42 cardiac patients, and were revised to make them more parsimonious. The final models were tested with a novel group of 647 CAD patients from Alberta, Canada (327 urban-living, 320 rural-living). The primary analysis was focused on determining the extent to which patients completing the survey fell in the correct behavioral group. Thereafter individual nodes were examined to determine decision-making constructs that were different between urban- and rural-living patients.

RESULTS

When tested, the models had overall accuracy of 93.5% for diet and 97.5% for physical activity. The most salient model nodes that led to differing behavioral outcomes reflected these constructs: perception of control over health; time, effort, or competing priorities; receipt of appropriate information; and appeal of the activity.

CONCLUSIONS

This information is potentially useful to assist healthcare providers to: (1) understand patients' decisions regarding their cardiac risk factor modification behavior, and (2) better direct conversations about risk factor modification and educational activities.

Skeletal effects of zoledronic acid in an animal model of chronic kidney disease

Bisphosphonates reduce skeletal loss and fracture risk, but their use has been limited in patients with chronic kidney disease. This study shows skeletal benefits of zoledronic acid in an animal model of chronic kidney disease.

INTRODUCTION

Bisphosphonates are routinely used to reduce fractures but limited data exists concerning their efficacy in non-dialysis chronic kidney disease. The goal of this study was to test the hypothesis that zoledronic acid produces similar skeletal effects in normal animals and those with kidney disease.

METHODS

At 25 weeks of age, normal rats were treated with a single dose of saline vehicle or 100 μg/kg of zoledronic acid while animals with kidney disease (approximately 30% of normal kidney function) were treated with vehicle, low dose (20 μg/kg), or high dose (100 μg/kg) zoledronic acid, or calcium gluconate (3% in the drinking water). Skeletal properties were assessed 5 weeks later using micro-computed tomography, dynamic histomorphometry, and mechanical testing.

RESULTS

Animals with kidney disease had significantly higher trabecular bone remodeling compared to normal animals. Zoledronic acid significantly suppressed remodeling in both normal and diseased animals yet the remodeling response to zoledronic acid was no different in normal and animals with kidney disease. Animals with kidney disease had significantly lower cortical bone biomechanical properties; these were partially normalized by treatment.

CONCLUSIONS

Based on these results, we conclude that zoledronic acid produces similar amounts of remodeling suppression in animals with high turnover kidney disease as it does in normal animals, and has positive effects on select biomechanical properties that are similar in normal animals and those with chronic kidney disease.

Weight and patients' decision to undergo cardiac surgery

Obese patients are less likely to have cardiac surgery than normal weight patients. This could be due to physician or patient decision-making. We undertook a qualitative descriptive study to explore the influence of obesity on patients' decision-making to have cardiac surgery. Forty-seven people referred for coronary artery bypass graft (CABG) surgery were theoretically sampled. Twelve people had declined cardiac surgery. Participants underwent in-depth interviews aimed at exploring their decision-making process. Data were analyzed using conventional content analysis. Though patients' weight did not play a role in their decision, their relationship with their cardiologist/surgeon, the rapidity and orchestration of the diagnosis and treatment, appraisal of risks and benefits, previous experience with other illness or others who had cardiac surgery, and openness to other alternatives had an impact. It is possible that there is a lack of comfort or acknowledgment by all parties in discussing the influence of weight on CABG surgery risks.

Using social exchange theory to guide successful study recruitment and retention

Participant attrition (withdrawal or loss after entering a study) is a major threat to the completion of valid studies. It can result in systematic error (selection bias), thus decreasing the statistical power of studies and limiting the generalisability of study findings. This paper demonstrates how key social exchange theory principles form the theoretical context for our practice, which, in turn enables us to form enduring relationships with study participants.

The influence of coronary artery bypass graft harvest site on women's pain, functional status, and health services utilization throughout the first post-operative year: a longitudinal study

BACKGROUND

Coronary artery bypass graft surgery is a commonly performed procedure aimed at managing coronary symptoms and prolonging life. Researchers have typically examined morbidity and mortality outcomes of predominantly male populations. Less is known about the influence of graft harvest site on recovery outcomes such as surgery-related pain, functional status, and health services utilization, especially in women.

OBJECTIVES

We aimed to examine the relationships between coronary artery bypass graft harvest site (saphenous vein, internal mammary arteries or both) and surgery-related pain, functional status, health services use at 6 weeks, 12 weeks and 12 months post-operatively.

DESIGN

Longitudinal extension survey following participation in a clinical trial.

SETTING

Ten Canadian centres.

PARTICIPANTS

Women (222) who participated in the Women's Recovery from Sternotomy Trial, underwent coronary artery bypass graft surgery with or without heart valve surgery, and completed the 12-month follow-up interview.

METHODS

Harvest site data were collected by health record audit at the time of hospital discharge. Surgery-related pain, functional status, pain medication use and health services use data were collected by standardized interview over the telephone at 6 weeks, 12 weeks and 12 months post-operatively. Surgery-related pain and functional status were measured using the short Health Assessment Questionnaire. Health services use was measured by questionnaire and recorded as reported by the participants.

RESULTS

Surgery-related pain, functional disability and health services use decreased over the first post-operative year. Participants who had left internal mammary artery grafts were more likely to have surgery-related pain (Adjusted Odds Ratio (AOR)=2.79; 95% Confidence Interval (CI) 1.40-5.70) and use pain medication (AOR=4.32; 95% CI 1.44-12.91) than those who had saphenous vein grafts. Conversely, participants who had saphenous vein grafts reported significantly more functional disability (AOR=2.63; 95% CI 1.16-6.25) over 12 months post-surgery than those with left internal mammary artery grafts. Participants who had pain over the course of follow-up were more likely to visit their family physician or nurse practitioner (p=0.017), visit another type of provider (i.e., naturopath or chiropractor, p=0.004), or use any health care service (p<0.0001).

CONCLUSIONS

Following coronary artery bypass graft surgery, women who had left internal mammary artery grafts reported more pain and health services use while those who had saphenous vein grafts were more functionally disabled. Women who reported surgery-related pain also used more health services.

Assessment of risk factors for cardiovasuclar disease in pediatric renal transplant patients

Pediatric renal TP recipients are at risk for CVD. We performed a cross-sectional study of the prevalence of RF for CVD in 45 long-term pediatric renal TP patients. The time since TP was 42 months. The GFR was 87.8 +/- 3.4 mL/min/1.73 m(2); 25/45 (56%) had Stage 2-4 CKD. A total of 33% had elevated SBP and 24% had high DBP; 57% had elevated SBP or DBP. A total of 20% had elevated serum CHOL levels, while 45% had high serum TG levels. A total of 42% had high HCY levels and 50% had low HCT levels. The vast majority (66.7%) had at least two RF for CVD. A total of 18.2% had abnormal post-TP echocardiography results. There was a negative correlation between GFR and SBP, DBP, serum CHOL, HCY, and BMI. There was a positive correlation between GFR and HCT. Serum CHOL was significantly lower and SBP and DBP trended lower in patients on a SF immunosuppression regimen. Similarly, SBP and DBP trended higher and CHOL was significantly higher in patients receiving SRL vs. mycophenolate mofetil. We conclude that the majority of pediatric renal TP patients exhibit multiple CVD RF.

First Nations people's challenge in managing coronary artery disease risk

First Nations peoples bring a particular history and cultural perspective to healing and well-being that significantly influences their health behaviors. The authors used grounded theory methods to describe and explain how ethnocultural affiliation and gender influence the process that 22 First Nations people underwent when making lifestyle changes related to their coronary artery disease (CAD) risk. The transcribed interviews revealed a core variable, meeting the challenge. Meeting the challenge of CAD risk management was influenced by intrapersonal, interpersonal (relationships with others), extrapersonal (i.e., the community and government), sociodemographic, and gendered factors. Salient elements for the participants included their beliefs about origins of illness, the role of family, challenges to accessing information, financial and resource management, and the gendered element of body image. Health care providers need to understand the historical, social, and culturally embedded factors that influence First Nations people's appraisal of their CAD.

Chinese immigrants' management of their cardiovascular disease risk

The authors have undertaken a series of grounded theory studies to describe and explain how ethnocultural affiliation and gender influence the process that cardiac patients undergo when faced with making behavior changes associated with reducing their cardiovascular disease (CVD) risk. Data were collected through audiorecorded semistructured interviews (using an interpreter as necessary), and the authors analyzed the data using constant comparative methods. The core variable that emerged through the series of studies was "meeting the challenge." Here, the authors describe the findings from a sample of Chinese immigrants (10 men, 5 women) to Canada. The process of managing CVD risk for the Chinese immigrants was characterized by their extraordinary diligence in seeking multiple sources of information to enable them to manage their health.

Men and women managing coronary artery disease risk: Urban–rural contrasts

People's beliefs about health and making lifestyle changes associated with risk reduction and disease prevention can vary based on their gender and ethnocultural affiliation. Our objective was to describe and explain how gender and ethnocultural affiliation influence the process that people undergo when faced with making lifestyle changes related to their coronary artery disease (CAD) risk. A series of grounded theory studies were undertaken in Alberta, Canada, with men and women from five ethnocultural groups diagnosed with CAD. Here, we describe the cultural aspects associated with urban- and rural-living in 42 Euro-Celtic men and women. Data were collected through semi-structured, audio-recorded interviews and analysed using constant comparative methods. The core variable that emerged through the process was 'meeting the challenge'. There were three phases to the process of managing CAD risk: pre-diagnosis/event, liminal self, and living with CAD. Intra-personal, inter-personal, extra-personal, and socio-demographic factors influenced the participants' capacity to meet the challenge of managing their CAD risk. The influence of these factors was either direct or indirect through the intertwined elements of the participants' knowledge about CAD and perceived extent of necessary change. Each element of this process was influenced by the participants' gender and culture (urban- versus rural-living). When healthcare providers understand and work with the gender- and ethnoculturally based components that influence people's appraisal of their cardiac health and their decision-making, appropriate secondary prevention interventions and positive health outcomes are more likely to follow.

Hypoxaemia enhances peripheral muscle oxidative stress in chronic obstructive pulmonary disease

BACKGROUND

Because oxidative stress affects muscle function, the underlying mechanism to explain exercise induced peripheral muscle oxidative stress in patients with chronic obstructive pulmonary disease (COPD) is clinically relevant. This study investigated whether chronic hypoxaemia in COPD worsens peripheral muscle oxidative stress and whether an abnormal muscle inflammatory process is associated with it.

METHODS

Nine chronically hypoxaemic and nine non-hypoxaemic patients performed repeated knee extensions until exhaustion. Biopsy specimens were taken from the vastus lateralis muscle before and 48 hours after exercise. Muscle oxidative stress was evaluated by lipid peroxidation (lipofuscin and thiobarbituric acid reactive substances (TBARs)) and oxidised proteins. Inflammation was evaluated by quantifying muscle neutrophil and tumour necrosis factor (TNF)-alpha levels.

RESULTS

When both groups were taken together, arterial oxygen pressure was positively correlated with quadriceps endurance time (n = 18, r = 0.57; p < 0.05). At rest, quadriceps lipofuscin inclusions were significantly greater in hypoxaemic patients than in non-hypoxaemic patients (2.9 (0.2) v 2.0 (0.3) inclusions/fibre; p < 0.05). Exercise induced a greater increase in muscle TBARs and oxidised proteins in hypoxaemic patients than in non-hypoxaemic patients (40.6 (9.1)% v 10.1 (5.8)% and 51.2 (11.9)% v 3.7 (12.2)%, respectively, both p = 0.01). Neutrophil levels were significantly higher in hypoxaemic patients than in non-hypoxaemic patients (53.1 (11.6) v 21.5 (11.2) counts per fibre x 10(-3); p < 0.05). Exercise did not alter muscle neutrophil levels in either group. Muscle TNF-alpha was not detected at baseline or after exercise.

CONCLUSION

Chronic hypoxaemia was associated with lower quadriceps endurance time and worsened muscle oxidative stress at rest and after exercise. Increased muscle neutrophil levels could be a source of the increased baseline oxidative damage. The involvement of a muscle inflammatory process in the exercise induced oxidative stress of patients with COPD remains to be shown.

Peripheral muscle endurance and the oxidative profile of the quadriceps in patients with COPD

BACKGROUND

Based on previously reported changes in muscle metabolism that could increase susceptibility to fatigue, we speculated that patients with chronic obstructive pulmonary disease (COPD) have reduced quadriceps endurance and that this will be correlated with the proportion of type I muscle fibres and with the activity of oxidative enzymes.

METHODS

The endurance of the quadriceps was evaluated during an isometric contraction in 29 patients with COPD (mean (SE) age 65 (1) years; forced expiratory volume in 1 second 37 (3)% predicted) and 18 healthy subjects of similar age. The electrical activity of the quadriceps was recorded during muscle contraction as an objective index of fatigue. The time at which the isometric contraction at 60% of maximal voluntary capacity could no longer be sustained was used to define time to fatigue (Tf). Needle biopsies of the quadriceps were performed in 16 subjects in both groups to evaluate possible relationships between Tf and markers of muscle oxidative metabolism (type I fibre proportion and citrate synthase activity).

RESULTS

Tf was lower in patients with COPD than in controls (42 (3) v 80 (7) seconds; mean difference 38 seconds (95% CI 25 to 50), p<0.001). Subjects in both groups had evidence of electrical muscle fatigue at the end of the endurance test. In both groups significant correlations were found between Tf and the proportion of type I fibres and citrate synthase activity.

CONCLUSION

Isometric endurance of the quadriceps muscle is reduced in patients with COPD and the muscle oxidative profile is significantly correlated with muscle endurance.

The influence of lung volume reduction surgery on exercise in patients with COPD

Although the influence of lung volume reduction surgery (LVRS) on incremental- and constant-power exercise is important in the evaluation of this procedure for patients with chronic obstructive pulmonary disease (COPD), it is rarely reported even in large randomised controlled trials. This report describes 39 patients with severe COPD ((mean +/- SE) forced expiratory volume in one second 32 +/- 2% pred, functional residual capacity 195 +/- 6% pred) who participated in a randomised controlled trial of LVRS and who completed incremental exercise tests at 6 months as well as endurance tests (constant power of 25 +/- 1 W) at 3, 9 and 12 months. Peak oxygen uptake (V'O2,pk) was similar between the treatment (n = 19) and control groups (n = 20) at baseline. After LVRS, the treatment group had a significantly greater V'O2,pk (mean difference (95% CI) 1.28 (0.07-2.50) mL x kg x min(-1)) and power (13 (6-20) W). The treatment group achieved a significantly greater minute ventilation (7.1 (2.9-11.3) L x min(-1)) with a greater tidal volume (0.16 (0.04-0.28) L). Baseline endurance was similar between groups. After surgery, there were significant between-group differences in endurance time, which were maintained at 12 months (7.3 (3.9-10.8) min). Lung volume reduction surgery is associated with an increase in exercise capacity and endurance, as compared with conventional medical treatment.

Influence of lung volume reduction surgery (LVRS) on health related quality of life in patients with chronic obstructive pulmonary disease

BACKGROUND

The clinical value of LVRS has been questioned in the absence of trials comparing it with pulmonary rehabilitation, the prevailing standard of care in COPD. Patients with heterogeneous emphysema are more likely to benefit from volume reduction than those with homogeneous disease. Disease specific quality of life is a responsive interpretable outcome that enables health professionals to identify the magnitude of the effect of an intervention across several domains.

METHODS

Non-smoking patients aged <75 years with severe COPD (FEV(1) <40% predicted, FEV(1)/FVC <0.7), hyperinflation, and evidence of heterogeneity were randomised to surgical or control groups after pulmonary rehabilitation and monitored at 3 month intervals for 12 months with no crossover between the groups. The primary outcome was disease specific quality of life as measured by the Chronic Respiratory Questionnaire (CRQ). Treatment failure was defined as death or functional decline (fall of 1 unit in any two domains of the CRQ). Secondary outcomes included pulmonary function and exercise capacity.

RESULTS

LVRS resulted in significant between group differences in each domain of the CRQ at 12 months (change of 0.5 represents a small but important difference): dyspnoea 1.9 (95% confidence interval (CI) 1.3 to 2.6; p<0.0001); emotional function 1.5 (95% CI 0.9 to 2.1; p<0.0001); fatigue 2.0 (95% CI 1.4 to 2.6; p<0.0001); mastery 1.8 (95% CI 1.2 to 2.5; p<0.0001). In the control group one of 27 patients died and 16 experienced functional decline over 12 months. In the surgical group four of 28 patients died and three experienced functional decline (hazard ratio = 3.1 (95% CI 1.3 to 7.6; p=0.01). Between group improvements (p<0.05) in lung volumes, flow rates, and exercise were sustained at 12 months (RV -47% predicted (95% CI -71 to -23; p=0.0002); FEV(1) 0.3 l (95% CI 0.1 to 0. 5; p=0.0003); submaximal exercise 7.3 min (95% CI 3.9 to 10.8; p<0.0001); 6 minute walk 66 metres (95% CI 32 to 101; p=0.0002).

CONCLUSIONS

In COPD patients with heterogeneous emphysema, LVRS resulted in important benefits in disease specific quality of life compared with medical management, which were sustained at 12 months after treatment.

In vitro and in vivo contractile properties of the vastus lateralis muscle in males with COPD

Peripheral muscle weakness is common in chronic obstructive pulmonary disease (COPD) but it is still under debate whether weakness is due to atrophy or contractile dysfunction. In vitro and in vivo contractile properties of the vastus lateralis muscle were studied in 16 patients with stable COPD (forced expiratory volume in one second 39 +/- 16% of predicted, age 67 +/- 4 yrs (mean +/- sD)) and nine sedentary control subjects. Isometric knee extensor strength was measured while mid-thigh muscle cross-sectional area (MTMCSA) was obtained using computed tomography. Muscle strips from the vastus lateralis obtained through open biopsy were rapidly suspended in an oxygenated Krebs-Ringer solution that was maintained at 35 degrees C with a pH of 7.40 to study their contractile properties. The isometric knee extensors strength/MTMCSA ratio was 0.50 +/- 0.08 versus 0.58 +/- 0.06 kg x cm(-2) for COPD and control subjects, respectively. The muscle bundle cross-sectional area (CSA) was 4.6 +/- 2.1 and 4.4 +/- 3.1 mm(-2), the length at which active tension was maximum was 15 +/- 4 and 15 +/- 3 mm, and maximal isometric peak forces normalised for CSA were 4.3 +/- 2.7 and 4.8 +/- 2.6 N x cm(-2) for COPD and control subjects, respectively. The force/frequency relationship tended to be shifted to the right in patients with COPD, meaning that a higher stimulation frequency was necessary to produce the same relative force. Patients with COPD had a lower proportion of type I fibre than controls (26 +/- 12% versus 39 +/- 11%) with reciprocal significant increase in type IIb fibre proportion (20+/-16% versus 8 +/- 4%). The proportion of type IIa fibres was similar between the two groups. These results suggest that the contractile properties of the vastus lateralis are preserved in patients with chronic obstructive pulmonary disease. Therefore, the reduction in the quadriceps strength in patients with chronic obstructive pulmonary disease cannot be explained on the basis of an alteration of the contractile apparatus.

Limitation of lower limb VO(2) during cycling exercise in COPD patients

Patients with chronic obstructive pulmonary disease (COPD) usually stop exercise before reaching physiological limits in terms of O(2) delivery and extraction. A plateau in lower limb O(2) uptake (VO(2)) and blood flow occurs despite progression of the imposed workload during cycling in some patients with COPD, suggesting that maximal capacity to transport O(2) had been reached and that it had been extracted in the peripheral exercising muscles. This study addresses this observation. Symptom-limited incremental cycle exercise was performed by 14 men [62 +/- 11 (SD) yr] with severe COPD (forced expiratory volume in 1 s = 35 +/- 7% of predicted value). Leg blood flow was measured at each exercise step with a thermodilution catheter inserted in the femoral vein. This value was multiplied by two to account for both working legs (Q(LEGS)). Arterial and femoral venous blood was sampled at each exercise step to measure blood gases. Leg O(2) consumption (VO(2LEGS)) was calculated according to the Fick equation. Total body VO(2) (VO(2TOT)) was measured from expired gas analysis, and tidal volume (VT) and minute ventilation (VE) were derived from the flow signal. In eight patients, VO(2LEGS) kept increasing in parallel with VO(2TOT) as external work rate was increasing. In six subjects, a plateau in VO(2LEGS) and Q(LEGS) occurred during exercise (increment of <3% between 2 consecutive increasing workloads) despite the increase in workload and VO(2TOT) [corresponding mean was 110 +/- 38 ml (11 +/- 4%)]. These six patients also exhibited a plateau in O(2) extraction during exercise. Peak exercise work rate was higher in the eight patients without a plateau than in the six with a plateau (51 +/- 10 vs. 40 +/- 13 W, P = 0.043). VT, VE, and dyspnea were significantly greater at submaximal exercise in patients of the plateau group compared with those of the nonplateau group. These results show that, in some patients with COPD, blood flow directed to peripheral muscles and O(2) extraction during exercise may be limited. We speculate that redistribution of cardiac output and O(2) from the lower limb exercising muscles to the ventilatory muscles is a possible mechanism.

Peripheral muscle dysfunction in chronic obstructive pulmonary disease

Peripheral muscle dysfunction is a common systemic complication of moderate to severe COPD and may contribute to disability, handicap, and premature mortality. In contrast to the lung impairment, which is largely irreversible, peripheral muscle dysfunction is potentially remediable with exercise training, nutritional intervention, oxygen, and anabolic drugs. Therapeutic success is often incomplete, however, and a better understanding of the mechanisms involved in the development of peripheral muscle dysfunction in COPD is needed to help develop innovative and more effective therapeutic strategies.

Oxidative enzyme activities of the vastus lateralis muscle and the functional status in patients with COPD

BACKGROUND

Enzymatic and histochemical abnormalities of the peripheral muscle may play a role in exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). A study was undertaken to measure the mitochondrial enzyme activity of the vastus lateralis muscle in patients with COPD and to evaluate the relationship between enzyme activities and functional status.

METHODS

Fifty seven patients with COPD of mean (SD) age 66 (7) years with forced expiratory volume in one second (FEV(1)) 39 (15)% predicted and peak oxygen uptake (VO(2)) of 14 (4) ml/min/kg and 15 normal subjects of similar age were included in the study. Each subject performed a stepwise exercise test up to maximal capacity during which five-breath averages of VO(2) were measured. Muscle specimens were obtained by percutaneous needle biopsy of the vastus lateralis muscle and the activity of two mitochondrial enzymes (citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HADH)) was measured. The functional status of the patients was classified according to peak VO(2).

RESULTS

CS and HADH activities were markedly reduced in patients with COPD compared with normal subjects (22.3 (2.7) versus 29.5 (7.3) micromol/min/g muscle (p<0.0001) and 5. 1 (2.0) versus 6.7 (1.9) micromol/min/g muscle (p<0.005), respectively). The activity of CS decreased progressively with the deterioration in the functional status while that of HADH was not related to functional status. Using a stepwise regression analysis, percentage predicted functional residual capacity (FRC), the activity of CS, oxygen desaturation during exercise, age, and inspiratory capacity (% pred) were found to be significant determinants of peak VO(2). The regression model explained 59% of the variance in peak VO(2) (p<0.0001).

CONCLUSIONS

The oxidative capacity of the vastus lateralis muscle is reduced in patients with moderate to severe COPD compared with normal subjects of similar age. In these individuals the activity of CS correlated significantly with peak exercise capacity and independently of lung function impairment.

Influence of work rate incremental rate on the exercise responses in patients with COPD

PURPOSE

The peak work rate (Wpeak) measured during a progressive stepwise exercise test is commonly used to select the target training intensity for an exercise training program. In healthy subjects, a greater Wpeak is achieved when a faster rate of increase in work rate is used, whereas VO2 peak is independent of the rate of increase in work rate. This effect might be even more pronounced in chronic obstructive pulmonary disease (COPD) patients, in whom the VO2 kinetics during exercise are slower compared with healthy subjects.

METHODS

To investigate this, we studied 10 COPD patients (9 M/1 F, age: 65+/-5 yr [mean +/- SD], FEV1: 33+/-8%). They underwent, on separate days, three stepwise exercise tests on an ergocycle. For each test, increments of 5, 10, or 20 W x min(-1) were used in random order; the investigator was blinded as to which increment was used. VO2, VCO2, heart rate (HR), minute ventilation (VE), breathlessness and leg fatigue at rest, at each work rate, and at maximal capacity were obtained.

RESULTS

Wpeak averaged 40+/-13, 53+/-14, and 66+/-19 W for the 5-, 10-, and 20-W protocol, respectively (P < 0.001), whereas VO2 peak was comparable at 0.96+/-0.16, 1.02+/-0.18, and 1.03+/-0.20 L x min(-1). As the rate of increase in work rate became faster, the VO2/work rate relationship shifted to the right. This is exemplified by the VO2 at 40 W, which averaged 0.98+/-0.06, 0.90+/-0.09, and 0.83+/-0.10 L x min(-1) for the 5-, 10-, and 20-W protocol, respectively (P < 0.05). Similar observations were made for the relationship between HR, VE, and symptom scores, and work rate. There was no significant differences in peak values for HR and VE, and symptoms scores.

CONCLUSIONS

We conclude that the work rate incremental rate influences the Wpeak achieved, whereas the peak values for VO2, HR, VE, and symptom scores remain comparable. These findings have practical implications for the exercise evaluation of patients with COPD.

Feasibility and efficacy of home exercise training before lung volume reduction

BACKGROUND

Exercise training is recommended before lung volume reduction surgery (LVRS) in patients with emphysema. Unfortunately, many of these patients are referred from remote areas where there is no available rehabilitation program. The authors evaluated the feasibility and efficacy of a minimally supervised home-based exercise training program.

METHODS

Twenty-three emphysematous patients (age 61 +/- 6, forced expiratory volume in 1 second = 29 +/- 7% predicted [mean +/- SD]) were recruited from our LVRS program. Measurements of pulmonary function, maximal and submaximal exercise capacity, 6-minute walking distance (6-MWD), muscle strength, and quality of life with the Chronic Respiratory Questionnaire were obtained before and after training. Home-based exercise training program included muscle exercises and aerobic training, and started with detailed teaching while the follow-up was ensured through weekly phone calls and a diary filled by each patient.

RESULTS

Significant increases in 6-MWD (P < 0.001), quality of life (P < 0.005), peak work rate (P < 0.05), peak oxygen consumption (P < 0.05), endurance time (P < 0.005), and muscle strength were observed in the home-based exercise training program.

CONCLUSIONS

Home-based exercise training for patients in preparation for LVRS was feasible, and induced significant improvement in exercise tolerance and quality of life.

Altered expression of myosin heavy chain in the vastus lateralis muscle in patients with COPD

This study was designed to further characterize peripheral skeletal muscle alterations in patients with chronic obstructive pulmonary disease (COPD) and to evaluate the possible relationship between myosin heavy chain (MyoHC) isoform expression and exercise tolerance in these individuals. MyoHC composition from biopsy of the vastus lateralis muscle was examined in 12 COPD patients (forced expiratory volume in one second (FEV1)=31+/-9% predicted, peak oxygen consumption (V'O2)=15+/-4 mL x kg(-1) x min(-1)) and 10 age-matched normal male subjects (peak V'O2=20+/-5 mL x kg(-1) x min(-1)). The proportion of MyoHC type I was smaller in COPD than in normals (27+/-17% versus 41+/-9%, p<0.05) with an increase in MyoHC type IIa (51+/-15% versus 39+/-9%, p<0.05) and the proportion of MyoHC type IIx being comparable between both groups. A significant relationship was found between peak V'Oo2 mL x kg(-1) x min(-1) and FEV1 % pred (r=0.91, p<0.0001) and the percentage of MyoHC type I (r=0.61, p=0.016). In stepwise multiple regression, only FEV1 % pred was found to be a significant determinant of peak V'O2 (p<0.0001). This variable explained 83% of the total variance of peak V'O2. In summary, this study showed considerable modifications in the phenotypic expression of the myosin heavy chain in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease. An independent effect of myosin heavy chain expression on exercise capacity was not found. These results suggest that chronic inactivity and muscle deconditioning may not be the sole factors explaining peripheral muscle dysfunction in patients with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease: capillarity and fiber-type characteristics of skeletal muscle

BACKGROUND

The purpose of this investigation was to compare capillarity and fiber type proportions of the vastus lateralis muscle between patients with chronic obstructive pulmonary disease (COPD) and healthy subjects.

METHODS

Fifteen male subjects were included in the study (8 COPD: 61.0 +/- 1.8 years [mean +/- SEM]; forced expiratory volume in 1 second 42.0 +/- 2.1% predicted; 7 N: age 54.0 +/- 1.1). Subjects were submitted to a symptom-limited maximal exercise test on ergocycle. After a transcutaneous biopsy of the vastus lateralis muscle, sections were cut 8 to 10 microns thick and stained with the Andersen method for capillarity and Stevens method for fiber typing.

RESULTS

Patients with COPD had a decrease in peak oxygen consumption compared with healthy subjects (1.2 +/- 0.1 versus 3.0 +/- 0.2 L/min). Number of capillaries per square millimeter was lower in patients with COPD versus healthy subjects (92.6 +/- 16.1 and 213.3 +/- 33.5, P < 0.001); percentages of fiber types were 43.5 +/- 5.5% type I, 56.5 +/- 5.5% type II in COPD, and 56.7 +/- 3.4% type I, 43.2 +/- 3.4% type II in healthy subjects (P < 0.05). In addition, capillaries/fiber ratio was 0.83 +/- 0.05 in COPD, and 1.56 +/- 0.10 in healthy subjects (P < 0.001).

CONCLUSION

As expected, patients with COPD showed a decrease in exercise capacity. The muscle analysis results indicate that patients with COPD have a greater proportion of type II fibers and a much lower capillaries/fiber ratio than normal subjects. We conclude that COPD adversely affects fiber type and capillarization of the lower limbs. This could be partly caused by deconditioning in these patients.

Peripheral muscle weakness in patients with chronic obstructive pulmonary disease

Peripheral muscle weakness is commonly found in patients with chronic obstructive pulmonary disease (COPD) and may play a role in reducing exercise capacity. The purposes of this study were to evaluate, in patients with COPD: (1) the relationship between muscle strength and cross-sectional area (CSA), (2) the distribution of peripheral muscle weakness, and (3) the relationship between muscle strength and the severity of lung disease. Thirty-four patients with COPD and 16 normal subjects of similar age and body mass index were evaluated. Compared with normal subjects, the strength of three muscle groups (p < 0.05) and the right thigh muscle CSA, evaluated by computed tomography (83.4 +/- 16.4 versus 109.6 +/- 15.6 cm2, p < 0.0001), were reduced in COPD. The quadriceps strength/thigh muscle CSA ratio was similar for the two groups. The reduction in quadriceps strength was proportionally greater than that of the shoulder girdle muscles (p < 0.05). Similar observations were made whether or not patients had been exposed to systemic corticosteroids in the 6-mo period preceding the study, although there was a tendency for the quadriceps strength/thigh muscle CSA ratio to be lower in patients who had received corticosteroids. In COPD, quadriceps strength and muscle CSA correlated positively with the FEV1 expressed in percentage of predicted value (r = 0.55 and r = 0. 66, respectively, p < 0.0005). In summary, the strength/muscle cross-sectional area ratio was not different between the two groups, suggesting that weakness in COPD is due to muscle atrophy. In COPD, the distribution of peripheral muscle weakness and the correlation between quadriceps strength and the degree of airflow obstruction suggests that chronic inactivity and muscle deconditioning are important factors in the loss in muscle mass and strength.

Reexamining the associate degree curriculum. Assessing the need for community concepts

Significant changes taking place in health care delivery in our community in Louisiana have led faculty to reexamine the associate degree nursing curriculum. We recognized the trend toward the decreased need for inpatient care and the greater need for outpatient care and home care in the community. In addition, we noted the need for nursing care to assist the elderly in the management of chronic illness and provide education on health promotion and disease prevention.

Metabolic and hemodynamic responses of lower limb during exercise in patients with COPD

Premature lactic acidosis during exercise in patients with chronic obstructive pulmonary disease (COPD) may play a role in exercise intolerance. In this study, we evaluated whether the early exercise-induced lactic acidosis in these individuals can be explained by changes in peripheral O2 delivery (O2). Measurements of leg blood flow by thermodilution and of arterial and femoral venous blood gases, pH, and lactate were obtained during a standard incremental exercise test to capacity in eight patients with severe COPD and in eight age-matched controls. No significant difference was found between the two groups in leg blood flow at rest or during exercise at the same power outputs. Blood lactate concentrations and lactate release from the lower limb were greater in COPD patients at all submaximal exercise levels (all P < 0.05). Leg D02 at a given power output was not significantly different between the two groups, and no significant correlation was found between this parameter and blood lactate concentrations. COPD patients had lower arterial and venous pH at submaximal exercise, and there was a significant positive correlation between venous pH at 40 W and the peak O2 uptake (r = 0.91, P < 0.0001). The correlation between venous pH and peak O2 uptake suggests that early muscle acidosis may be involved in early exercise termination in COPD patients. The early lactate release from the lower limb during exercise could not be accounted for by changes in peripheral O2. The present results point to skeletal muscle dysfunction as being responsible for the early onset of lactic acidosis in COPD.

Intensity of training and physiologic adaptation in patients with chronic obstructive pulmonary disease

The applicability of high-intensity training and the possibility of inducing physiologic adaptation to training are still uncertain in patients with severe chronic obstructive pulmonary disease (COPD). The purposes of this study were to evaluate the proportion of patients with moderate to severe COPD in whom high-intensity exercise training (30-min exercise session at 80% of baseline maximal power output [Wmax]) is feasible, and the response to training in these patients. We also sought to evaluate the possible influence of disease severity on the training intensity achieved and on the development of physiologic adaptation following endurance training. Forty-two patients with COPD (age = 66 +/- 7 yr, FEV1 = 38 +/- 13% predicted, [mean +/- SD]) were evaluated at baseline and after a 12-wk endurance training program. Each evaluation included a stepwise exercise test on an ergocycle up to the individual maximal capacity during which minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production (VCO2), and arterial lactic acid concentrations were measured. The training consisted of 25 to 30-min exercise sessions on a calibrated ergocycle three times a week, with a target training intensity at 80% of Wmax. The training intensity was adjusted with the objective of reaching the target intensity, but also to ensure that the cycling exercise could be maintained for the specified duration. The training intensity sustained for the duration of each exercise session averaged 24.5 +/- 12.6, 51.7 +/- 17.4, 63.8 +/- 22.4, and 60.4 +/- 22.7% of Wmax at Weeks 2, 4, 10, and 12, respectively. High-intensity training was achieved in zero, three, five, and five patients at Weeks 2, 4, 10, and 12, respectively. A significant increase in VO2max and Wmax occurred with training (p < 0.0002). This improvement in exercise capacity was accompanied by a 6% and 17% reduction in VE and in arterial lactic acid concentration for a given work rate, respectively (p < 0.0001), suggesting that physiologic adaptation to training occurred. The intensity of training achieved, in % Wmax, was not influenced by the initial VO2max, age, or FEV1. The effects of training were compared in patients with an FEV1 > or = 40% or < 40% predicted. Percent changes in VO2max, Wmax, and VE, were significant and of similar magnitude for both groups, whereas the decrease in arterial lactic acid for a given work rate reached statistical significance only in those patients with an FEV1 > or = 40% predicted. We conclude that although most patients were unable to achieve high-intensity training as defined in this study, significant improvement in their exercise capacity was obtained and physiologic adaptation to endurance training occurred. The training intensity expressed as a percent of the individual maximum exercise capacity, and the relative effectiveness of training, were not influenced by the severity of airflow obstruction.

Skeletal muscle adaptation to endurance training in patients with chronic obstructive pulmonary disease

The purpose of this study was to evaluate the physiologic responses to endurance training in patients with moderate to severe airflow obstruction by specifically looking at changes in skeletal muscle enzymatic activities. Eleven patients (age = 65 +/- 7 yr, mean +/- SD, FEV1 = 36 +/- 11% of predicted value, range = 24 to 54%) were evaluated before and after an endurance training program. Each evaluation included a percutaneous biopsy of the vastus lateralis and a stepwise exercise test on an ergocycle up to his/her maximal capacity. VE, VO2, VcO2, and serial arterial lactic acid concentration were measured during the exercise test. The activity of two oxidative enzymes, citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HADH), and of three glycolytic enzymes, lactate dehydrogenase, hexokinase, and phosphofructokinase was determined. The training consisted of 30-min exercise sessions on a calibrated ergocycle, 3 times a week for 12 wk. The aerobic capacity was severely reduced at baseline (VO2max = 54 +/- 12% of predicted) and increased by 14% after training (p < 0.05). For an identical exercise workload, there was a significant reduction in VE (34.5 +/- 10.0 versus 31.9 +/- 9.0 L/min, p < 0.05) and in arterial lactic acid concentration (3.4 +/- 1.3 versus 2.8 +/- 0.9 mmol/L, p < 0.01) after training. The lactate threshold also increased after training (p < 0.01) while the activity of the three glycolytic enzymes was similar at the two evaluations. In contrast, the activity of CS and HADH increased significantly after training (22.3 +/- 3.5 versus 25.8 +/- 3.8 mumol/min/g muscle for CS, p < 0.05, and 5.5 +/- 2.9 versus 7.7 +/- 2.5 mumol/min/g for HADH, p < 0.01). A significant inverse relationship was found between the percent changes in the activity of CS and HADH, and the percent changes in arterial lactic acid during exercise (p = 0.01). We conclude that endurance training can reduce exercise-induced lactic acidosis and improve skeletal muscle oxidative capacity in patients with moderate to severe chronic obstructive pulmonary disease (COPD).

Oxidative capacity of the skeletal muscle and lactic acid kinetics during exercise in normal subjects and in patients with COPD

Early lactic acidosis during exercise and abnormal skeletal muscle function have been reported in chronic obstructive pulmonary disease (COPD) but a possible relationship between these two abnormalities has not been evaluated. The purpose of this study was to compare and correlate the increase in arterial lactic acid (La) during exercise and the oxidative capacity of the skeletal muscle in nine COPD patients (age = 62 +/- 5 yr, mean +/- SD, FEV1 40 +/- 9% of predicted) and in nine normal subjects of similar age (54 +/- 3 yr). Following a transcutaneous biopsy of the vastus laterialis, each subject performed a stepwise exercise test on an ergocycle up to his or her maximal capacity during which 5-breath averages of oxygen consumption (Vo2), and serial La concentration measurements were obtained. From the muscle biopsy specimen, the activity of two oxidative enzymes, citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HADH), and of three glycolytic enzymes, lactate dehydrogenase, hexokinase, and phosphofructokinase were determined. The La/Vo2 relationship during exercise was fitted by an exponential function in the form La = a + bvo2, where be represents the shape of the relationship. The activity of the oxidative enzymes was significantly lower in COPD than in control subjects (22.8 +/- 3.3 versus 36.8 +/- 8.6 mumol/min/g muscle for CS, and 3.1 +/- 1.1 versus 5.5 +/- 1.4 mumol/min/g for HADH, p < 0.0005) and the increase in lactic acid was steeper in COPD (b = 4.3 +/- 2.0 versus 2.1 +/- 0.2 for normal subjects, p = 0.0005). A significant inverse relationship was found between CS, HADH, and b. No difference was found between the two groups for the glycolytic enzymes. We conclude that in COPD the increase in arterial La during exercise is excessive, the oxidative capacity of the skeletal muscle is reduced, and that these two results are interrelated.

Evaluation of the emphysematous patient

Most of the patients with emphysema complain of dyspnea and become limited in their activities during the course of the disease. Dyspnea is probably due to the change in the configuration of the thorax which is secondary to hyperinflation. The investigation should include the radiologic quantification of the structural abnormalities of the lungs and the functional consequences of these changes. When volume reduction of the lung is considered, the effects of hyperinflation on the mechanic of breathing and the ventilatory response to exercise has to be investigated rigorously.

Functional outcome of patients with chronic obstructive pulmonary disease and exercise hypercapnia

Chronic hypercapnia is associated with a poor prognosis in chronic obstructive pulmonary disease (COPD). Some patients are normocapnic at rest but retain CO2 during exercise. The significance of this abnormality on the course of the disease is unknown. Sixteen stable COPD patients (13 males and 3 females, aged 60 +/- 5 yrs, mean +/- SD) who had previously undergone pulmonary function tests and progressive exercise testing with arterial blood sampling at rest and maximal capacity, entered the study. At first evaluation (E1), subjects were normocapnic at rest (arterial carbon dioxide tension (Pa,CO2): 4.9-5.7 kPa, (37-43 mmHg)) and all presented exercise-induced hypercapnia (end-exercise Pa,CO2 > 5.7 kPa (43 mmHg) with a minimal 0.5 kPa (4 mmHg) increase from resting value). The subjects were re-evaluated 24-54 months later (34 +/- 8 months) (second evaluation (E2)). At E2, forced expiratory volume in one second (FEV1) had decreased from 42 +/- 13 to 38 +/- 15% of predicted values, and mean resting Pa,CO2 had increased from 5.2 +/- 0.3 to 5.7 + 0.4 kPa. Maximal exercise capacity (Wmax) decreased between E1 and E2 from 76 +/- 30 to 56 +/- 22 W. Even if Wmax was lower at E2, end-exercise, Pa,CO2 was higher than at E1 (6.6 +/- 0.8 vs 6.4 +/- 0.5 kPa). At E2, eight subjects presented resting hypercapnia (group H), whilst the others remained normocapnic (Group N). Group H subjects had higher Pa,CO2, at Wmax than Group N and lower Wmax than Group N at E2.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiotherapy: an effective treatment of cerebral involvement by lymphomatoid granulomatosis

We report the case of a 40-year-old woman who presented with neurologic complications of lymphomatoid granulomatosis after an initial pulmonary presentation. After treatment failure with immunosuppressive therapy, she responded dramatically to cranial radiation therapy without prior surgery.

Effects of lung resection on pulmonary function and exercise capacity

The effects of lung resection on exercise capacity and perception of symptoms were studied in 47 patients aged 39-73 (mean 58.3) years. Twenty had a pneumonectomy and 27 a lobectomy, all for lung cancer. Forced expiratory volume, maximal inspiratory and expiratory pressures, and progressive maximal one minute incremental cycle ergometer exercise performance were measured before and after surgery. Breathlessness and leg discomfort were assessed with a modified Borg scale (0-10). Mean FEV1 decreased from 79% (SD 22%) to 53% (11%) of the predicted value after pneumonectomy and from 89% (22%) to 74% (18%) after lobectomy. Exercise capacity, measured as the highest work load completed, Wmax, decreased from 78% (25%) to 58% (28%) predicted in the pneumonectomy group and from 77% (21%) to 67% (20%) in the lobectomy group. There was only a weak relation between changes in FEV1 and changes in Wmax (r = 0.54, r2 = 0.30). The slope of the relation between the intensity of dyspnoea and work load or the intensity of dyspnoea and ventilation increased significantly after pneumonectomy, but not after lobectomy. Leg discomfort increased more rapidly when related to work load after both pneumonectomy and lobectomy. After resection dyspnoea was rarely the only limiting factor at maximal exercise. It is concluded that (1) change in FEV1 is a poor predictor of change in exercise capacity after lung resection; (2) pneumonectomy results in a 25% decrease in Wmax and in an appreciable increase in dyspnoea during exercise; (3) lobectomy has little or no effect on Wmax or the intensity of postoperative dyspnoea; (4) after both pneumonectomy and lobectomy leg discomfort makes an important contribution to exercise limitation.

In situ right ventricular thrombus secondary to heparin induced thrombocytopenia

Heparin induced thrombocytopenia (HIT) is a relatively common complication of heparin therapy, occurring in approximately 5% of patients treated with this drug. HIT may be associated with diffuse arterial and venous thrombosis. The case of a patient without underlying heart disease who developed a right ventricular thrombus and recurrent pulmonary emboli in association with and possibly as a complication of HIT is reported. Ancrod was used as an alternative to heparin for the time required to obtain an effective oral anticoagulant effect. The patient recovered completely and has no residual right ventricular thrombus.

[The usefulness of an exercise test on a treadmill shortly after a myocardial infarction]

A program of reconditioning through walking was prescribed for 130 patients following an exercise test on a treadmill 3 weeks after a myocardial infarction. At 8 and at 12 weeks the patients again underwent an exercise test. The protocol is safe and permits the detection of angina, arrhythmias and dyspnea during the exercise, thus avoiding delays in treatment. The heart rate and the systolic blood pressure were measured at the end of each stage of the test and after 3 minutes of recuperation. About 75% of the patients attained the target energy output of the two submaximal tests (4 and 7 mets at 3 and 8 weeks respectively); an output of 7 mets permits a patient to resume his or her usual daily activities. The results of the tests at 3 and 12 weeks (the latter a maximal test) showed that the probability of an aerobic capacity of 7 mets or greater at 12 weeks is 86% if the 3-week test is completed. Clinical observations alone did not have the same prognostic value 3 weeks after the infarction.

In vitro and in vivo effects of ethanol on the formation of endoperoxide metabolites in rat platelets

Preincubation of rat platelet-rich plasma (PRP) with ethanol resulted in dose-dependent inhibition of the formation of endoperoxide metabolites (EPM) when the PRP was aggregated by collagen suspension. The inhibition was manifested at concentrations normally attainable in blood of rats or humans by tolerable amounts of ethanol ingestion. Paradoxically, chronic ingestion of ethanol caused enhanced synthesis of EPM in platelets, indicating that the inhibitory effect of ethanol would be temporary, and that it can be reversed as soon as ethanol is eliminated. The level of arachidonic acid in platelet phospholipids of rats fed the ethanol diet was not different from that of the control, indicating that availability of immediate precursor acid would not be a factor for the enhanced synthesis of EPM in the ethanol group. This result suggested that platelets from rats subjected to chronic ethanol ingestion become hyperactive in synthesizing EPM through an unknown mechanism. When citrated whole blood was incubated in the presence of collagen suspension, amounts of EPM synthesized in the ethanol group were not different from those of the control group, but this was due to significant reduction of platelet counts in the ethanol group. Whether the effect of ethanol on other tissues would be similar to that on platelets is unknown. It is tempting to speculate that some of the pathological changes resulting from alcoholism might be mediated through the effect of ethanol on EPM formation.

Heparin inhibits the formation of endoperoxide metabolites in rat platelets: aspirin-like activity

Amounts of thromboxane A2 (TXA2) synthesized during the collagen-induced aggregation was much higher in citrated PRP than in heaprinized PRP implying that heparin might inhibit the synthesis of endoperoxide metabolites besides its anticoagulant action. Preincubation of citrated PRP with heparin resulted in dose dependent inhibition of the formation of TXA2 and PGE2. At the high concentration, heparin also inhibited the aggregation of citrated platelets induced by collagen indicating that heparin possesses aspirin-like activity. The significance of this finding is that the antithrombotic effect of heparin is probably due to not only its anticoagulant effect but also inhibition of the formation of arachidonic acid metabolites by platelets.