Connie Paladenech

Reproducibility of the 6-Minute Walk Test for Ambulatory Oxygen Prescription

Background: Ambulatory oxygen is frequently prescribed for patients with chronic obstructive pulmonary disease (COPD) who have oxygen desaturation ≤88% during exercise. The 6-min walk test (6MWT) with continuous pulse oximetry monitoring is a common method to document this oxygen desaturation, but the reproducibility of this test in determining the need for ambulatory oxygen in patients with COPD is not well documented. Objective:The aim of this study was to establish the reproducibility of the 6MWT in determining the need for ambulatory oxygen prescription in stable COPD patients using the Centers for Medicare and Medicaid (CMS) criteria for ambulatory oxygen prescription. Methods:The study was designed as a prospective observational study in an academic health center and associated pulmonary rehabilitation program. Eighty-eight COPD patients referred to pulmonary rehabilitation underwent continuous pulse oximetry while performing standard 6MWT on 3 separate days. Results: Fifty-one (58%) of these patients desaturated by continuous pulse oximetry to an SpO2 ≤88% on a least one of the 6MWTs. Only 26 patients (30%) demonstrated consistency in meeting the criteria for ambulatory oxygen set forth by the CMS on all three 6MWT with a κ statistic of 0.62. The percent agreement between 6MWTs for ambulatory oxygen prescription was 72% and the paired observation was 51%. Conclusions: The 6MWT distance is simple and widely used as a consistent measure of functional capacity in patients with COPD; however, the 6MWT oxygen saturation has only modest reproducibility in determining the need for ambulatory oxygen in stable COPD patients undergoing pulmonary rehabilitation.

Effect of Chronic Kidney Disease and Supplemental Polyunsaturated Fatty Acid Use on Exercise Levels During Cardiac Rehabilitation in Patients With Coronary Artery Disease.

PURPOSE: The correlation between chronic kidney disease (CKD) and increased cardiovascular disease-related mortality is well established. Cardiac rehabilitation (CR) improves exercise capacity, quality of life, and risk factors in patients with coronary artery disease (CAD). Data on the benefits of CR in patients with CKD are sparse. The purpose of this study was to compare outcomes after CR in patients with CAD but normal renal function, versus those with CAD and CKD. METHODS: We studied 804 patients with CAD entering an exercise-based CR program. Demographics, risk factors, exercise capacity in metabolic equivalent levels (METs), and estimated glomerular filtration rate (GFR) were recorded before and after the 3-month CR program. Use of polyunsaturated fatty acid (PUFA) was determined by medical records review. Stage III-V CKD (GFR <60 mL/min/1.73 m2) was present in 170 patients at baseline. RESULTS: After CR, METs improved in all patients, although increases in patients with a GFR 30 to 59 mL/min/1.73 m2 (&Dgr;1.6) and a GFR <30 (&Dgr;1.2) were smaller than those in patients with a GFR ≥60 (&Dgr;2.6, P < .05 vs GFR 30-59 and GFR <30). In patients with a GFR ≥60 mL/min/1.73 m2, PUFA use was associated with a 20% greater increase in MET levels compared with nonusers (&Dgr;3.0 vs &Dgr;2.5, P = .02); and in patients with a GFR 30 to 59, PUFA use was associated with 30% increase in MET level compared with nonusers (&Dgr;2.0 vs &Dgr;1.4, P = .03). These observations persisted after multivariable adjustment for baseline MET level, demographics, and risk factors. CONCLUSIONS: Potential mitigation by PUFA of the smaller improvement in exercise capacity with decreasing GFR requires confirmation in prospective randomized trials.

Degree and Direction of Change of Body Weight in Cardiac Rehabilitation and Impact on Exercise Capacity and Cardiac Risk Factors

Cardiac rehabilitation (CR) improves functional capacity and reduces mortality in patients with cardiovascular disease. It also improves cardiovascular risk factors and aids in weight reduction. Because of the increase in morbidly obese patients with cardiovascular disease, the prevalence of obesity and patterns of weight change in those undergoing CR merit fresh study. We studied 1,320 participants in a 12-week CR program at our academic medical center. We compared 5 categories: 69 class III obese (body mass index [BMI] ≥40) patients, 128 class II obese patients (BMI 35.0 to 39.9), 318 class I obese patients (BMI 30.0 to 34.9), 487 overweight patients (BMI 25.0 to 29.9), and 318 normal weight patients (BMI 18.5 to 24.9). Exercise capacity in METs, weight, blood pressure, and fasting lipid profile were measured before and after CR. Overall, 131 patients gained weight, 827 had no significant weight change, and 363 lost weight (176 lost 3% to 5% of their baseline weight, 161 lost 5% to 10%, and 26 lost >10%). Exercise capacity, blood pressure, and low-density lipoprotein cholesterol improved in all patients. Class III obese patients had the smallest improvement in peak METs (p <0.001), but the greatest weight loss. Patients who lost >10% of their baseline weight had the greatest improvements in exercise capacity, low-density lipoprotein, and triglycerides. In conclusion, after CR, a minority of patients lost weight. Most patients had no significant weight change and some even gained weight. The greatest loss was seen in class III obese patients. All patient groups showed improvements in exercise capacity and risk factors, regardless of the direction or degree of weight change.

A GREATER WEIGHT LOSS IS AEEN IN SEVERELY OBESE PATIENTS THAN IN OTHERS UNDERGOING CARDIAC REHABILITATION

Cardiac rehabilitation (CR) improves functional capacity and reduces mortality in coronary heart disease patients. Moderately obese individuals improve functional capacity with CR although whether severely obese individuals (body mass index, BMI ≥40) do so is unknown. We hypothesized that