|Home | About | Journals | Submit | Contact Us | Français|
Background and Purpose: Cardiac rehabilitation (CR) promotes positive outcomes following coronary artery bypass grafting (CABG) surgery. Patients with end-stage renal disease (ESRD), who have an increased risk of cardiac mortality and mobility, have also experienced positive outcomes following CABG. However, participation in CR continues to be limited due to lack of physician referrals, patient compliance, accessibility, and time. Can a CR program be implemented safely and effectively following CABG in a patient during dialysis sessions? Case Description: The patient was a 43-year-old male with a history of: ESRD requiring hemodialysis (HD), CABG, hypertension (HTN), and hyperlipidemia. During HD treatments, the patient received CR that included aerobic exercise and education for 16 weeks (26 visits) under the supervision of a physical therapist. Outcomes: The patient gained improvements in: 2-minute walk distance, quality of life (QOL), based on the Short Form-36 (SF-36), and a reduction in modifiable cardiac risk factors. No adverse events occurred during the intervention. Discussion: A 16-week CR program was implemented safely and effectively following CABG in a patient undergoing concurrent dialysis. This patient demonstrated improved outcomes comparable to patients who receive traditional cardiac rehabilitation following CABG.
Cardiac rehabilitation (CR) has been widely recognized as a standard intervention in the treatment of coronary artery disease (CAD), post myocardial infarction, and coronary artery bypass grafting (CABG).1–3 Benefits of CR have been well documented in the literature.1 The goal of CR is to provide secondary intervention of CAD by risk factor modification.1,2 Proven benefits include improved quality of life (QOL), exercise tolerance, general health, and a decrease in mortality and morbidity.1 Hedback et al3 showed a decline in cardiac events and hospital readmission following a CR program after CABG. The authors concluded a CR program might contribute to an improved long-term prognosis. Scrutinio et al4 recognized the importance of CR following CABG for patients with increased co-morbidities, specifically chronic obstructive pulmonary disease (COPD), diabetes (DM), peripheral vascular disease, and renal disease. Although the conclusions of this review article must be interpreted with caution, the authors surmised that these populations might benefit more from CR compared to patients without co-morbidities.
As in the general population, cardiovascular disease is the leading cause of mortality for patients with end-stage renal disease (ESRD). However, cardiovascular mortality is up to 40 times greater for patients receiving dialysis.5 Coronary artery bypass grafting has been shown to provide successful outcomes for people with renal dysfunction.6 However, the 3-year survival rate of a person with a left ventricular ejection fraction (LVEF) ≤ 35% coupled with renal dysfunction following CABG is only 68% compared to 90% of those following CABG with normal renal function.4 Kutner et al7 found when adding CR following CABG, patients on hemodialysis (HD) had a 35% reduced risk for all causes of mortality and a 36% reduced risk for cardiac death compared with patients on HD who did not receive CR. Following CABG, patients on HD who participated in CR were associated with longer survival time at 42 months and a high cost effectiveness ratio when compared to the same population who did not participate in CR.8
Despite the recognized benefits for CR, limited participation continues to exist for all populations. Barriers to CR include lack of physician referrals, transportation issues, poor patient compliance, and comorbidities.1,2,4,7 Kunter et al7 found in the HD population, of those who qualified for CR following CABG, only 10% participated compared to 23.4% participation in those following CABG without requiring HD. The authors speculated an increase in CR participation might occur when the patients receive dialysis in a hospital-based dialysis center that would be located closer to a CR program.7 Limited participation may also be due to the time constraints of HD treatment. For example, HD consists of up to 4-hour sessions 3 days a week; therefore, the burden of participation in CR coupled with HD may be significant. Perhaps combining these interventions may be feasible. Currently, there are no studies that examine performing CR during HD sessions for a patient with ESRD following CABG.
Studies have shown that patients with ESRD have positive outcomes following exercise programs performed during HD.9–14 Improvements have been noted in exercise tolerance, SF-36 scores, and a reduction of cardiac risk factors.9–13
Cheema et al9 performed a systematic review investigating 29 randomized control trials (RCT) that used exercise as a modality for patients requiring dialysis. The authors concluded exercise may have a positive effect on physical function and quality of life. Limitations the authors noted were inadequate reporting of compliance, outcomes, etiology of renal failure, and co-morbidities. The authors also recommended exercise prescription specifically defined in frequency, intensity, mode, duration, and supervision.
Toussaint et al10 investigated the effects an exercise program during HD would have on the reduction of cardiovascular risks. Nine participants used a bicycle ergometer during HD sessions for 3 months, while 10 participants performed no exercise. The results showed a small but significant decrease in brain natriuretic peptide (BNP) and a decrease in arterial compliance, measured by pulse wave velocity, following the 3-month intervention. These markers were reassessed following a 1-month period of no exercise, which demonstrated an increase in the above markers. The authors concluded exercise during HD was safe and may reduce cardiovascular risks therefore improving survival in patients on HD.
Literature supports the low rates of a cardiac event during traditional CR.1,2 Studies have not systematically examined the risk of exercising during HD; however, several authors have anecdotally reported no adverse effects when performing exercise during HD.9–11,13,14 One study found exercise performed during the last hour of dialysis led cardiac output, stroke volume, and mean arterial pressure to decrease significantly therefore limiting and even precluding the benefits/safety of exercise.14 Because of this observation, it is recommended that exercise be performed within the first 2 hours of initiating HD.11,14 Based on the current literature, the benefits of exercising during HD may outweigh the potential risks for the patient with CAD. Unfortunately, there is limited research demonstrating specifically how to prescribe an exercise program. Co-morbidities typically accompanying ESRD such as CAD, DM, hypertension (HTN), and heart failure, may affect normal physiological responses to aerobic exercise.15 Health care professionals, specifically trained in recognizing abnormal exercise response, may play a crucial role in successful outcomes.
The purpose of this case report is to answer the question: can a CR program be implemented safely and effectively following CABG in a patient during HD sessions? The focus of the intervention was to improve the patient's exercise tolerance, QOL, and reduce cardiac risk factors. A second purpose is to demonstrate the physical therapist's clinical decision process in recommending and implementing a safe CR program during HD.
The patient was a 43-year-old male who received single vessel CABG following unsuccessful percutaneous coronary intervention. His past medical history included: IgA nephropathy, an autoimmune disease that led to ESRD at age 35. He received 3 unsuccessful kidney transplants resulting in need for HD treatment (3 times a week, 4 hours each session) for the last 5 years. Further past medical history included: hyperlipidemia, sedentary lifestyle, labile HTN, and atrial fibrillation that was successfully treated by the Maze procedure during CABG. The patient lived with his wife, was on disability, and was awaiting a 4th renal transplant evaluation. The patient received phase I CR led by a physical therapist following CABG. He spent 5 days in the hospital setting. Prior to the patient's discharge from the hospital, he received a prescription for phase II CR from his physician.
Because of the time constraints of his HD schedule and the distance he was required to travel, the patient felt he would be unable to participate in a phase II CR program. A plan of care using the International Classification of Functioning Disability and Health model (ICF)16 was implemented by the treating physical therapist. The ICF model allowed the physical therapist to recommend and design a rehabilitation option based on the patient's impairments, activity limitations, participation restrictions, and environmental and personal factors while considering his health conditions (Figure (Figure1).1). Using the support of current literature and the ICF model as a guide, it was recommended by the physical therapist that participation in a physical therapist supervised CR program during HD sessions may be beneficial. The patient's cardiovascular surgeon, cardiologist, and nephrologist supported the recommendation. Traditional CR programs typically include: physician referral, symptom-limited graded exercise stress test prior to entry, exercise prescription, supervised exercise sessions using various cardiovascular exercise equipment, patient education, vital sign monitoring, telemetry, and physician availability on premises.2 In order to perform CR in the dialysis center, modifications to traditional CR were necessary and are further discussed throughout this case report. The physical therapist supervised nontraditional phase II CR program was initiated at the dialysis center 4 weeks following the patient's discharge from the hospital.
A review of systems demonstrated normal strength, range of motion, and gait. His resting blood pressure was 190/110 mmHg; heart rate was 55 beats per minutes with regular rate and rhythm, and oxygen saturation was 97% on room air. Breath sounds were normal, no audible S3 or S4 heart sounds were noted. His height was 180.3 cm, weight was 84 kg, and body mass index was 26. Baseline assessment including medications and serum cholesterol levels can be found in Tables Tables11–3. Functional capacity, QOL, and cardiac risk factors were also examined preintervention. Findings and rational for these selected tests and measures are as follows:
Functional capacity assessment and physical therapy intervention were initially deferred as the patient's elevated resting blood pressure was a relative contraindication to exercise testing according to the American College of Sports Medicine Guidelines (ACSM).17 The patient's nephrologist was notified. Functional capacity assessment and intervention were to begin on the following HD session; however, the patient's resting blood pressure was again elevated (162/100 mmHg). On the third attempt, the patient's resting blood pressure was 160/100 mmHg. While these readings did not contraindicate exercise testing per the ACSM, the treating physical therapist felt contacting the patient's nephrologist and cardiologist to notify them of his continued elevated blood pressures would be of benefit prior to data collection. Both physicians opted to allow functional capacity assessment and intervention with close monitoring. The American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR) recommends a symptom-limited graded exercise stress test prior to entering a traditional CR program.2 Because this patient did not have a symptom-limited graded exercise test prior to beginning the nontraditional CR program, the 6-minute walk test (6MWT) was initially selected to assess the patient's functional capacity. The 6MWT has been validated and recommended for several different populations including patients with ESRD.17,18 Because this patient continued to display resting HTN, the clinical decision was to use the 2-minute walk test (2MWT) therefore, blood pressure would be assessed more rapidly. The 2MWT has been used in a variety of patient populations including individuals with pulmonary disease, heart disease, and amputations.19–21 The 2MWT was developed for individuals who may not be able to tolerate traditional testing such as the 12-minute or 6-minute walk tests.21 A recent study by Brooks et al19 investigated the construct validity and sensitivity of the 2MWT in subjects following cardiac surgery. They found the 2MWT was sensitive to change and showed moderate correlation with measures of physical functioning such as the SF-36.
The patient's QOL was measured using the SF-36, a tool that has been used for assessing health related QOL outcomes in clinical practice and research for over 20 years.22–29 The SF-36 has been found to be a valid and reliable test of QOL for patients with ESRD.22 The SF-36 has also been used for assessing functional outcomes for patients who participated in a traditional CR program.28,29 On assessment, the patient scored 29.14 for the physical component scale (PCS) and 49.74 for the mental component scale (MCS). The patient's PCS and MCS scores were low compared to the general population (PCS 50 ±10, MCS 50 ± 10).23
The patient's modifiable cardiac risk factors were the following: hypertension, hyperlipidemia, and sedentary lifestyle based on self-report. The patient's elevated BMI was not chosen as an outcome measure due to the influence of fluid fluctuations that occur in this patient population.
The goals following physical therapy intervention were: improved functional capacity measured by increased distance covered on the 2MWT, improved QOL measured by increased SF-36 scores, and a reduction in modifiable cardiac risk factors.
Guidelines for the intervention were based on recommendations provided by the AACVPR,2 the ACSM,17 and the HD exercise programs provided by the current literature. Aerobic exercise using a stationary bicycle was the chosen mode of exercise. Multiple studies have used this mode of exercise with patients undergoing HD.9–13 Aerobic exercise was performed during each HD session and initiated within the first 2 hours of HD as recommended by the literature.11,14 Unlike traditional CR programs, telemetry was not used because the equipment was not available in the dialysis center. In the event of a medical emergency, the dialysis nursing staff was prepared to provide medical support until emergency services arrived.
The AACVPR guidelines recommend an exercise intensity of 50% to 80% of peak exercise capacity in order to provide a training effect.2 Because the patient was receiving β-blocker therapy, resulting in a blunted heart rate response to exercise, the Borg Rate of Perceived Exertion (RPE) scale was used to monitor exercise intensity.2,17 The patient was instructed to maintain an RPE of 11–13 (fairly light to somewhat hard) on a 6–20 scale in order to achieve cardiovascular benefits.2,17 The AACVPR also recommends exercise duration of 30 to 60 minutes of continuous or intermittent aerobic activity.2 Because of the limited literature providing specific guidelines for exercise prescription for patients receiving HD, exercise progression for this patient was as follows: aerobic exercise was to be performed within the first 2 hours of each HD treatment and exercise intensity and duration were gradually increased over the duration of the intervention. Initially, the patient performed interval training consisting of varying intensity in order to prolong exercise time. The patient's initial exercise duration began with 11 interval minutes while maintaining a speed of 2.87 kph – 5.45 kph. The patient's exercise duration was increased 2–3 minutes each visit if he was able to maintain an RPE of 11–13 and ≥ 5 kph. The goal for exercise duration was ≥ 30 continuous minutes while maintaining a RPE between 11–13 and a speed of > 5 kph. Vital signs (heart rate, blood pressure, oxygen saturation) and RPE were assessed before and during exercise, during cool-down, and following cessation of exercise until his blood pressure approached his initial resting blood pressure. The patient was also questioned regarding any complaints such as nausea, shortness of breath, dizziness, or fatigue. Education was provided by the supervising physical therapist during exercise sessions that included: risk factor modification, signs and symptoms of myocardial infarction, angina, heart failure, and exercise intolerance. The dialysis center dietitians provided nutritional education. Data collection occurred for 16 weeks.
The patient demonstrated an asymptomatic orthostatic blood pressure response (> 20 mmHg) during exercise sessions while on HD and during the 2MWT. This is a relative contraindication to terminate exercise.17 Because of the scarcity within the literature involving subjects similar to this patient, the physical therapist felt it would be prudent to report the orthostatic responses to the patient's nephrologist and cardiologist for further cardiovascular assessment. Subsequently, the patient received an echocardiogram and cardiac catheterization to assess cardiac function. All tests were reported to be within normal limits. The physicians opted to proceed with physical therapist supervised intervention. Heart rate, rhythm, and oxygen saturation did not raise concern during the intervention phase.
Data were collected during each HD session for 16 weeks. A total of 41 sessions were attempted and 26 sessions were recorded. There were a total of 15 treatment days in which exercise intervention was not performed due to complaints of nausea, diagnostic tests, leg cramps, vacation time, and shortness of breath due to pulmonary effusions. Not included in the data collection were 3 days in which exercise sessions were supervised by another physical therapist, and days between HD sessions during which the patient exercised independently.
Table Table11 depicts the results of the functional capacity assessment. Following the intervention, the patient increased the amount of distance covered in the 2MWT from 112m to 157m (40.18% improvement). He demonstrated improvements in his perceived QOL based on his SF-36 scores (Table (Table2).2). He improved in his physical component summary scale by 10 points (34.41% change) and his mental component summary scale by 7 points (15.68% change). His cardiac risk factor modifications (Table (Table3)3) included a reduction in both resting systolic blood pressure (Figure (Figure2),2), and diastolic blood pressure (Figure (Figure3)3) and an increase in routine participation of cardiovascular exercise. Following the 16-week intervention, he had a reduction in hypertension medications. His total cholesterol was reduced; however, he continued to have low HDL and a subsequent increase in his cholesterol medication was prescribed. Additional positive outcomes included: narrowing of his orthostatic blood pressure response during exercise sessions (Figure (Figure4)4) and during the 2MWT (Table (Table1).1). Exercise duration increased from 11 interval minutes to 40 continuous minutes. Exercise intensity increased from 2.87 kph to 5.45 kph. Subjective functional outcomes included: the ability to climb a flight of steps, perform light yard work, and play with his grandchildren without shortness of breath. In addition the patient stated he experienced a decreased incidence of restless leg syndrome during HD and he initiated a home walking program on his non-dialysis days. Aside from his asymptomatic orthostatic hypotension, no adverse events during the intervention were noted. Because the patient's resting blood pressures were within appropriate limits following the 16-week intervention, a 6MWT was performed as well as the 2MWT and discussed further in the discussion section. The patient achieved a distance of 426.72m during the 6MWT.
Compared to a traditional CR program, this case report demonstrated similar outcomes subsequent to providing CR, during HD sessions, to a patient following CABG. Improvements were observed in exercise tolerance, QOL, and cardiac risk factors.
Improved outcomes achieved in the distance covered during the 2MWT have been similarly reported by Brooks et al,19 who found that immediately following heart surgery, patients without ESRD had a 2MWT mean distance of 84m postoperatively, which increased to an mean of 151m at 6 to 8 weeks follow-up. The patient in this case report had a similar improvement. However, Brooks et al19 did not address if any of the subjects in their study participated or were participating in a CR program at the 6 to 8 week follow-up period. When comparing the 6MWT outcome to patients who completed a traditional CR program, the patient's distance of 426.72m was within one standard deviation of reported distances by Verrill et al.29 Painter et al24 reported prior to exercise training, individuals with ESRD covered a distance of 347m but following a HD exercise program, the distance improved to 373.74m. Following intervention, the patient in this case report demonstrated a greater 6 MW distance than Painter et al's subjects. Accounting for this outcome may be that our patient was younger than Painter et al's subjects (mean age 55.9 years) and our patient had supervised exercise for a duration of 16 weeks versus 8 weeks for Painter et al's subjects.
The patient's improvement in health related QOL, as measured by the SF-36, is supported by the literature in both the CR and ESRD population and may predict outcomes regarding mortality and morbidity.22–29 Lowrie et al26 investigated the ability of the SF-36 to predict morbidity (hospitalizations) and mortality within 6 months for patients with ESRD. They found for every 1-point increase in PCS there was an associated 2% reduction in mortality rate. The PCS score was also significantly associated with hospitalization and for every 1-point increase in the PCS score a 2% reduction in odds of hospitalization occurred. A 2% reduction of mortality was also noted with every 1–point increase in the MCS score. DeOreo et al25 reported for every increase in PCS score of 5 points one would have approximately a 10% increase in survival over a 6 month time frame. The patient in this case report demonstrated a 10.61-point increase in his PCS score which, according to the referenced studies, may decrease his risk of death within 6 months by 21.22%. Clinically, this may buy the patient time while awaiting a renal transplant. The patient in this study had a 34.41% improvement in his PCS scores that exceeds the minimal clinical important difference (MCID) as reported by Steffen et al.30 Additional studies have shown improved SF-36 scores following cardiovascular exercise for patients on HD.22,24,27 Ouzouni et al27 and Painter et al24 found significant improvements in PCS scores following their exercise program however found no significant changes with the MCS scores. The authors attributed these findings to the acceptance of chronic disease state over time such that outlook on the disease process does not change, which is reflected in stationary MCS scores. The patient in this study did have a positive change in his MCS scores, however did not exceed the MCID as reported by Steffen et al.30 This may be attributed to initial discomfort followed by subsequent healing after the open-heart surgery. When compared to the general population, the patient's SF-36 scores, prior to intervention, were well below the norm and reported scores within the ESRD population.23,24 However following intervention the patient's PCS score improved to slightly above the norm within the ESRD population. The SF-36 scores have also been shown to improve following traditional CR programs.28,29
One of the goals of CR is to reduce the risk factors associated with CAD.1–3,17 The risk factors associated with this patient were hypertension, hyperlipidemia, and sedentary lifestyle. It is well documented that cardiovascular exercise programs can reduce hypertension including in the HD population.1,2,9,17 The patient experienced a substantial reduction in his resting systolic and diastolic pressure following the intervention. The clinical implication was the avoidance of invasive surgery to remove his 3 donated kidneys, which his nephrologist speculated might subsequently still be releasing renin, therefore contributing to his labile hypertension. Secondly, the reduction in medications following intervention may have reduced the financial burden of his disease. The patient's results were in agreement with additional studies that showed exercise to be an adjunct to medication to help control blood pressure in patients requiring HD.13,31
A second potential cardiovascular benefit following the intervention was the decrease in exercise induced orthostatic hypotension. Toussaint et al10 found improved arterial compliance following a 3-month HD exercise program and Parsons et al32 found lower pulse pressures for subjects who participated in a HD exercise program versus subjects who did not. It should not be overlooked that one possible contributing factor to his exercise hypotension may have been fluid withdrawal during the HD process. However, as recommended by the literature,11,14 exercise was specifically initiated within the first 2 hours of HD to reduce the potential for hypotension. A majority of this patient's exercise sessions were commenced 30 minutes following initiation of HD. Moreover, the patient exhibited orthostasis while performing activity on land as demonstrated during the 2MWT. Perhaps improvements in his orthostasis may be explained by cardiovascular adaptations.10,13,32
Cardiac rehabilitation has been shown to improve cholesterol levels by decreasing LDL and increasing HDL serum levels.1 However, the patient in this case report did not show favorable cholesterol changes. While the patient's total cholesterol levels decreased, his HDL levels also decreased over time leading to an increased dosage of cholesterol medication. The lack of positive change in this patient's serum cholesterol profile may be attributed to his exercise intensity. Kraus et al33 noted serum cholesterol improvements were greater in subjects who exercised at higher intensity than subjects who exercised at lower intensities. However, even subjects who exercised at lower intensities had favorable serum cholesterol outcomes. We are unable to explain why the patient in this case study did not have such a response. Interestingly, a systematic review only noted one randomized controlled trial that reported improvements in cholesterol levels following an HD exercise program.9
Functional capacity assessment using the 2MWT and the 6MWT did not include practice tests, which may decrease variability.34 While all exercise sessions were initiated within the first 2 hours of HD, not all sessions occurred at this precise time. Therefore, fluid withdrawal from the dialysis process may have affected both resting and exercise blood pressure results. The cause of the patient's ESRD was an autoimmune disease rather than hypertension or diabetes mellitus, which are the leading contributors to ESRD and representative of the subjects studied within the reported literature. The patient was younger than subjects studied in both the CR and HD literature. Exercise consistency varied due to vacation time, nausea, diagnostic tests, and leg cramps. Data were not collected regarding the patient's self-initiated home walking program. Alterations to a traditional CR program were required in order to provide services to the patient. Telemetry was not available; therefore, the ability to detect cardiac ischemia and cardiac arrhythmias was not available. The patient did not have a symptom-limited graded exercise stress test therefore the 2MWT was administered. The stationary bicycle was the only mode of exercise available whereas in traditional CR settings, a variety of exercise equipment is typically used. Lastly, reimbursement for services rendered was not obtained, as current Medicare guidelines deny reimbursement for physical therapy or CR provided in a dialysis center.35 Feasibility of this practice must be taken into consideration and poses reimbursement challenges, which is an essential area for future research.
After participating in a 16-week supervised CR program during HD, the patient demonstrated improvements in his exercise tolerance, QOL, and risk factor modification, specifically reduced blood pressure and increased routine participation in cardiovascular exercise. The goals of a traditional CR program were achieved but in a nontraditional setting. Exercising during HD following CABG allowed the patient to participate in a safe and supervised environment at a feasible place and time, thus potentially improving program adherence and fostering a life-long exercise program. The physical therapist was instrumental in recommending and developing an exercise program and communicated abnormal exercise response to the appropriate physicians. Further research is needed in specific exercise prescription, and to assess long-term benefits of exercising patients during HD with CAD that may facilitate reimbursement opportunities.