Extrinsic Threshold PEEP Reduces Post-exercise Dyspnea in COPD Patients: A Placebo-controlled, Double-blind Cross-over Study

PURPOSE

Most patients with chronic obstructive pulmonary disease (COPD) complain of dyspnea during and following exercise, and the development of intrinsic positive end-expiratory pressure (PEEP) is thought to contribute to lung hyperinflation and dyspnea. Many people with COPD use pursed lip breathing (PLB) in an attempt to produce extrinsic PEEP to reduce lung hyperinflation and dyspnea during and following exertion. We hypothesized that the use of a threshold, extrinsic PEEP device would reduce post-exercise dyspnea in people with COPD.

METHODS

A double blind, crossover study was conducted on post-exercise dyspnea in 8 patients with COPD whose exercise tolerance was limited by dyspnea. Subjects performed two identical 6-minute treadmill bouts that led to a Borg dyspnea rating of at least 5/10. Dyspnea, heart rate, and oxygen-hemoglobin saturation (SpO(2)) were recorded at rest, every 2 minutes during exercise and at 2, 5, and 10 minutes post-exercise. Immediately following the exercise bouts, the subjects used either a threshold PEEP device for 6 breaths at 10 cm H(2)O or a Sham device.

RESULTS

Heart rate and SpO(2) were not different between treatments any time point before, during, or after exercise. Dyspnea ratings were not different between devices at rest or during exercise, but were lower in the post-exercise period following use of PEEP (p < 0.05). When asked which device, if any, the subjects would prefer to use to relieve post-exercise dyspnea, 7 of 8 chose the PEEP device and one had no preference.

CONCLUSIONS

We found that the use of a PEEP device can help reduce postexercise dyspnea in patients with COPD.

Effects of endurance training on cardiorespiratory fitness and substrate partitioning in postmenopausal women

We examined the effect of endurance training on energy substrate partitioning during rest and exercise in postmenopausal women. Ten healthy sedentary (55 +/- 1 years old) subjects completed 12 weeks of endurance exercise training on a cycle ergometer (5 d/wk, 1 h/d, 65% peak oxygen consumption [Vo(2)peak]). Whole-body energy substrate oxidation was determined by indirect calorimetry during 90 minutes of rest and 60 minutes of cycle ergometer exercise. Subjects were studied at 65% Vo(2)peak before training and after training at the same absolute exercise intensity (same absolute workload as 65% of pretraining Vo(2)peak) and same relative exercise intensity (65% of posttraining Vo(2)peak). After training, Vo(2)peak increased by 16.3% +/- 3.9% and resting heart rate decreased by 4 beats per minute (P < .05). During exercise at same absolute intensity, mean arterial pressure decreased by 8 mm Hg (P < .05), heart rate decreased by 19 beats per minute (P < .05), energy derived from carbohydrate decreased by 9.6%, and the energy derived from lipid increased by 9.2% (P < .05). Lactate concentration was lower at the same absolute and relative exercise intensities (P < .05). Changes in substrate partitioning during exercise were accomplished without changes in dietary composition, body weight, or body composition. We conclude that endurance training in healthy postmenopausal women who remain in energy balance results in many of the classic cardiopulmonary training effects, decreases the reliance on carbohydrate, and increases lipid oxidation during a given submaximal exercise task without a reduction in body weight.

Concussion in sports: postconcussive activity levels, symptoms, and neurocognitive performance

CONTEXT

Evidence suggests that athletes engaging in high-intensity activities after concussion have more difficulties with cognitive recovery.

OBJECTIVE

To examine the role postinjury activity level plays in postconcussive symptoms and performance on neurocognitive tests in a population of student-athletes.

DESIGN

Retrospective cohort study with repeated measures of neurocognitive performance and symptom reporting.

SETTING

University-based sports concussion clinic.

PATIENTS OR OTHER PARTICIPANTS

Ninety-five student-athletes (80 males, 15 females: age = 15.88 +/- 1.35 years) were retrospectively assigned to 1 of 5 groups based on a postinjury activity intensity scale.

MAIN OUTCOME MEASURE(S)

We employed a regression analysis for repeated measures to evaluate the relationship of activity intensity to symptoms and neurocognitive outcome up to 33 days after concussion. Postconcussion symptom scores and neurocognitive (verbal memory, visual memory, visual motor speed, and reaction time) scores served as the primary outcome measures.

RESULTS

Level of exertion was significantly related to all outcome variables (P < .02 for all comparisons). With multivariate analysis, activity intensity remained significant with respect to visual memory (P = .003) and reaction time (P < .001).

CONCLUSIONS

Activity level after concussion affected symptoms and neurocognitive recovery. Athletes engaging in high levels of activity after concussion demonstrated worse neurocognitive performance. For these tasks, those engaging in moderate levels of activity demonstrated the best performance.

Left atrial size may predict exercise capacity and cardiovascular events in patients with heart failure

Our aim was to investigate, in patients with heart failure, the relationship between left atrial size and exercise capacity and cardiovascular events. Seventy-five patients (67 men and 8 women; mean age, 53.4 +/- 8.8 yr) with left ventricular ejection fractions of < or =0.45 (New York Heart Association functional classes I-III) were matched by age and sex with 20 healthy control subjects. Echocardiographic examinations were performed, as was exercise testing by the modified Bruce protocol. Patients were monitored for a period of 330 to 480 days for cardiac death or for heart failure that required hospitalization. The indexed left atrial diastolic size (beta level = -0.534, P <0.001) and left ventricular late diastolic filling velocity (beta level = 0.247, P <0.017) were the most important values in predicting low exercise capacity. The only independent predictor of low exercise capacity (<5 METS) was the indexed left atrial diastolic size (odds ratio, 1.428; 95% confidence interval, 1.09-1.702; P <0.001). Every 1 mm/m2 increase in indexed left atrial diastolic dimension caused a 42.8% increase in the risk of severe heart failure (exercise capacity, <5 METS). Independent predictors for cardiovascular events were indexed as left atrial systolic size (odds ratio, 1.383; 95% confidence interval, 1.145-1.671; P <0.001) and left ventricular early diastolic/late diastolic filling velocity (odds ratio, 1.096; 95% confidence interval, 1.010-1.189; P <0.027). Indexed left atrial diastolic and left atrial systolic size predict exercise capacity and cardiovascular events, respectively, in New York Heart Association functional class I through III heart failure patients.

Performance on the Balance Error Scoring System Decreases After Fatigue

OBJECTIVE: To determine the immediate effects of a whole-body fatigue protocol on performance of the Balance Error Scoring System (BESS), a postural-stability test commonly used as part of a concussion-assessment battery. DESIGN AND SETTING: Subjects were assigned to a fatigue or control group and were assessed before and immediately after a 20-minute fatigue protocol or rest period. SUBJECTS: Fourteen fatigue subjects and 13 control subjects participated in this study. All subjects were male and free of vestibular disorders, and none had suffered a mild head injury or lower extremity injury in the preceding 6 months, as described through self-report. MEASUREMENTS: We measured performance on the BESS for 9 stance-surface conditions and summed each condition to obtain a total score. Using the Borg scale, we also measured ratings of perceived exertion before, during, and after the fatigue protocol or rest period. RESULTS: We found a significant increase in total errors from pretest to posttest in the fatigue group (14.36 +/- 4.73 versus 16.93 +/- 4.32), a significant decrease in errors in the control group (13.32 +/- 3.77 versus 11.08 +/- 3.88), and a significant difference between groups on the posttest. The rating of perceived exertion scores were significantly different between the fatigue and control groups at the middle (13.29 +/- 1.59 versus 6.23 +/- 0.83) and end (15.86 +/- 2.38 versus 6.15 +/- 0.55) of the fatigue or rest period. CONCLUSIONS: The BESS error scores increased immediately after the fatigue protocol, demonstrating that balance ability diminished. Clinicians who use the BESS as part of their sideline assessment for concussion should not administer the test immediately after a concussion due to the effects of fatigue.

Risk of upper respiratory tract infection in athletes: an epidemiologic and immunologic perspective

OBJECTIVE

The chronic and acute immune responses to both heavy and moderate exercise are reviewed, with guidelines provided for the prevention and management of upper respiratory tract infection (URTI) in athletes.

DATA SOURCES

Epidemiologic and experimental exercise immunology research data were used. The MEDLINE database was searched for the years 1970 to 1997 with the terms "exercise," "immune," "infection," "lymphocyte," and "neutrophil."

DATA SYNTHESIS

A descriptive review with summary figures and one table.

CONCLUSIONS/RECOMMENDATIONS

The epidemiologic data suggest that endurance athletes are at increased risk for URTI during periods of heavy training and the 1-to 2-week period after marathon-type race events. Several researchers have reported a diminished neutrophil function in athletes during periods of intense and heavy training. Following each bout of prolonged heavy endurance exercise, several components of the immune system appear to demonstrate suppressed function for several hours. This has led to the concept of the "open window," described as the 3- to 12-hour time period after prolonged endurance exercise when host defense is decreased and the risk of URTI is elevated. There is sufficient evidence for sports medicine professionals to encourage athletes to practice various hygienic measures to lower their risk of URTI and to avoid heavy exertion during systemic illness.

Indications and choices in pacemaker therapy

During their 33-year history of clinical use, cardiac pacemakers have evolved from devices primarily intended to save lives into complex systems designed to improve the cardiac patient's overall quality of life. To help physicians cope with this rapidly changing field, this review outlines current indications for pacemaker therapy and examines the wide range of options available. After describing the standard nomenclature for identifying the various systems, the author discusses pacemaker selection on the basis of cardiac rhythm alone, as well as rate-modulated therapy.

The physiological response of siberian husky dogs to exercise: effect of interval training

Five Siberian Husky Dogs participated in an initial study to determine their physiological response to three types of exercise. Blood samples were taken prior to, and three minutes following, a 7.5 km free run and 6 km team sled run for the determination of hemoglobin, hematocrit, red and white blood cell counts, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, lactate dehydrogenase, creatine phosphokinase and serum glutamic pyruvic transaminase. Samples were also taken following a 90s sprint run. Heart rate was taken immediately after each run by palpation of the femoral pulse. Average heart rates following the 90s, 7.5 km and 6 km runs were 190 bpm, 211 bpm and 166 bpm, respectively. Mean lactate concentrations following the 90s, 7.5 km and 6 km runs were 1.74 mMol . 1(-1), 0.70 mMol . 1(-1), and 3.06 mMol . 1(-1), respectively. Elevation of lactate dehydrogenase and creatine phosphokinase was greatest following the 6 km sled run. Three of the above dogs were then studied before and after a 12 week interval training program, while three other dogs served as controls. The animals completed a three stage, submaximal treadmill test prior to and following the program. Pre and post blood samples were taken, and rectal temperature and heart rate were recorded continuously throughout the test. An analysis of variance was used to examine the significance of differences between and within groups. Although the response of heart rate, lactate, temperature and serum enzymes to submaximal exercise did not change with training significant differences between groups suggested that a more prolonged program may have resulted in such adaptations.