Andrew William Sheel

Optimizing pulmonary rehabilitation in chronic obstructive pulmonary disease - practical issues: A Canadian Thoracic Society Clinical Practice Guideline

Pulmonary rehabilitation (PR) participation is the standard of care for patients with chronic obstructive pulmonary disease (COPD) who remain symptomatic despite bronchodilator therapies. However, there are questions about specific aspects of PR programming including optimal site of rehabilitation delivery, components of rehabilitation programming, duration of rehabilitation, target populations and timing of rehabilitation. The present document was compiled to specifically address these important clinical issues, using an evidence-based, systematic review process led by a representative interprofessional panel of experts. The evidence reveals there are no differences in major patient-related outcomes of PR between nonhospital- (community or home sites) or hospital-based sites. There is strong support to recommend that COPD patients initiate PR within one month following an acute exacerbation due to benefits of improved dyspnea, exercise tolerance and health-related quality of life relative to usual care. Moreover, the benefits of PR are evident in both men and women, and in patients with moderate, severe and very severe COPD. The current review also suggests that longer PR programs, beyond six to eight weeks duration, be provided for COPD patients, and that while aerobic training is the foundation of PR, endurance and functional ability may be further improved with both aerobic and resistance training.

Cardiovascular Responses to Vibrostimulation for Sperm Retrieval in Men With Spinal Cord Injury

Abstract Background/Objective: Cardiovascular abnormalities and arrhythmias are common in individuals with spinal cord injury (SCI) who are undergoing vibrostimulation for sperm retrieval. The study aimed to examine cardiovascular control in men with SCI undergoing this procedure. Methods: Individuals with chronic cervical (n = 8; age: 33.1 ± 1.9 years) and upper thoracic SCI (n = 5; age: 35.2 ± 2.9 years) volunteered for vibrostimulation, with continuous blood pressure (Finometer) and electrocardiographic monitoring. Patients were characterized further by sympathetic skin responses (SSR) to assess descending autonomic spinal pathways and American Spinal Injury Association (ASIA) scores to assess motor and sensory pathways. Results: All but one subject with cervical SCI were ASIA A or B and were negative for SSR in the hands and feet. All subjects with upper thoracic SCI were ASIA A or B and were positive for SSR in the hands. Systolic blood pressure was lower in men with cervical injury at rest. Vibrostimulation induced an increase in systolic blood pressure >20 mmHg in all patients with cervical SCI (range = 125/65-280/152; median = 167/143 mmHg) and in 2 thoracic subjects (151/104 and 170/121 mmHg). During ejaculation, 6 cervical and 3 thoracic subjects developed arrhythmias (5 with bradycardia, 6 with premature atrial contractions, 4 with ventricular excitation, 1 with junctional rhythm, and 1 with heart block). Conclusion: The vibrostimulation procedure induced electrocardiographic abnormalities and autonomic dysreflexia in subjects with either cervical or high thoracic SCI.

SEX DIFFERENCES IN EXERCISE-INDUCED DIAPHRAGMATIC FATIGUE IN ENDURANCE-TRAINED ATHLETES

There is evidence that female athletes may be more susceptible to exercise-induced arterial hypoxemia and expiratory flow limitation and have greater increases in operational lung volumes during exercise relative to men. These pulmonary limitations may ultimately lead to greater levels of diaphragmatic fatigue in women. Accordingly, the purpose of this study was to determine whether there are sex differences in the prevalence and severity of exercise-induced diaphragmatic fatigue in 38 healthy endurance-trained men (n = 19; maximal aerobic capacity = 64.0 +/- 1.9 ml x kg(-1) x min(-1)) and women (n = 19; maximal aerobic capacity = 57.1 +/- 1.5 ml x kg(-1) x min(-1)). Transdiaphragmatic pressure (Pdi) was calculated as the difference between gastric and esophageal pressures. Inspiratory pressure-time products of the diaphragm and esophagus were calculated as the product of breathing frequency and the Pdi and esophageal pressure time integrals, respectively. Cervical magnetic stimulation was used to measure potentiated Pdi twitches (Pdi,tw) before and 10, 30, and 60 min after a constant-load cycling test performed at 90% of peak work rate until exhaustion. Diaphragm fatigue was considered present if there was a >or=15% reduction in Pdi,tw after exercise. Diaphragm fatigue occurred in 11 of 19 men (58%) and 8 of 19 women (42%). The percent drop in Pdi,tw at 10, 30, and 60 min after exercise in men (n = 11) was 30.6 +/- 2.3, 20.7 +/- 3.2, and 13.3 +/- 4.5%, respectively, whereas results in women (n = 8) were 21.0 +/- 2.1, 11.6 +/- 2.9, and 9.7 +/- 4.2%, respectively, with sex differences occurring at 10 and 30 min (P < 0.05). Men continued to have a reduced contribution of the diaphragm to total inspiratory force output (pressure-time product of the diaphragm/pressure-time product of the esophagus) during exercise, whereas diaphragmatic contribution in women changed very little over time. The findings from this study point to a female diaphragm that is more resistant to fatigue relative to their male counterparts.

The effect of repeat exercise on pulmonary diffusing capacity and EIH in trained athletes

PURPOSE The purpose of this study was to determine the effects of repeated heavy exercise on postexercise pulmonary diffusing capacity (DL) and the development of exercise induced arterial hypoxemia (EIH). METHODS 13 endurance-trained, male athletes (age = 27+/-3 yr, height = 179.6+/-5.0 cm, weight = 71.8+/-6.9 kg, VO2max = 67.0+/-3.6 mL x kg(-1) x min(-1) performed two consecutive, continuous exercise tests on a cycle ergometer to VO2max, separated by 60 min of recovery. Arterial oxygen saturation (%SaO2) was measured via ear oximetry, and resting DL was measured and partitioned by the single-breath method, before exercise and 60 min after each exercise bout. RESULTS No significant differences resulted in VO2max, VE, peak heart rate (HR), or breathing frequency between exercise bouts (P > 0.05). There was a small but significant decrease (454-446 W; P < 0.05) in peak power output in the second test. %SaO2 decreased from resting values during both exercise tasks, but there was no difference between the minimum saturation achieved in test 1 (91.4) or test 2 (91.6; P > 0.05). After the initial exercise bout, significant decreases (P < 0.05) occurred in DL (11%), membrane diffusing capacity (DM) (11%) and pulmonary capillary volume (VC) (10%). Further decreases occurred in DL (6%; P < 0.05), DM (2%; P > 0.05), and VC (10%; P < 0.05) after the second exercise bout. CONCLUSIONS These observations question the meaning of post exercise measurements of pulmonary diffusion capacity, and its components, relative to pulmonary gas exchange and pulmonary fluid accumulation during exercise. The fact that there was no further change in %SaO2 after the second test suggests that if any interstitial edema developed, it was of no clinical significance; alternatively, the changes in DL(CO) may be related more to redistribution of blood than the development of pulmonary edema.

Child obesity and fitness levels among Kenyan and Canadian children from urban and rural environments: A KIDS-CAN Research Alliance Study

OBJECTIVE This study was designed to gather anthropometric and fitness-related data on Kenyan children living in urban (UKEN) and rural (RKEN) environments and to compare them with previous data collected on Canadian children in order to examine the potential nutrition-physical activity transition. METHODS Height, weight, waist circumference, triceps skinfolds were directly measured on rural (RKEN) and urban Kenyan (UKEN) children (n = 179, 9-13 years) and compared with existing data from Canadian children living in urban and rural environments (n = 274, 9-13 years). Aerobic fitness was measured using the 20 m shuttle run, flexibility using the sit-and-reach test and isometric handgrip strength was assessed. RESULTS None of the RKEN children were overweight or obese (OWO). However, 6.8% of UKEN boys and 16.7% of girls were OWO. The RKEN children had lower BMI, waist circumference, and triceps skinfolds than all other groups (UKEN, and Canadian: p < 0.05). UKEN children were leaner than Canadian children (p < 0.05). Male and female RKEN children had higher running speeds, and aerobic fitness than UKEN children (p < 0.001). Isometric strength was not different between Kenyan groups and was not different from urban living Canadian children. UKEN children were the least flexible group, and girls were more flexible than boys in all groups. CONCLUSIONS Urban Kenyan children appear to be showing signs of the nutrition-physical activity transition, as judged by the anthropometric similarities to contemporary living Canadian children. Further support is provided by examining the difference in prevalence of overweight/obesity among UKEN compared with their RKEN counterparts and their lower aerobic fitness level.

Effects of exercise training and inspiratory muscle training in spinal cord injury: a systematic review.

Abstract Objective: To provide a systematic review of the studies assessing exercise training and inspiratory muscle training (IMT) in individuals for the improved respiratory function of patients with spinal cord injury (SCI). Methods: Thirteen studies (5 exercise training, 8 IMT) were identified. Articles were scored for their methodological quality using the Physiotherapy Evidence Database scores and Downs and Black tools for randomized and nonrandomized studies, respectively. Conclusions were based on the most rigorously executed studies using Sacketts levels of evidence. Results: Study comparison was compromised by diverse research designs; small sample sizes; and heterogeneity of studied populations, protocols, and outcome measures. Based on current literature, there is level 2 evidence supporting exercise training as an intervention to improve respiratory strength andendurance and level 4 evidence to support exercise training as an intervention that might improve restingand exercising respiratory function in people with SCI. There is level 4 evidence to support IMT as anintervention that might decrease dyspnea and improve respiratory function in people with SCI. Conclusions: There are insufficient data to strongly support the use of exercise training or IMT for improved respiratory function in people with SCI. There is some evidence of efficacy of both regimens; however, the evidenceis not of the best possible quality.

The time course of pulmonary diffusing capacity for carbon monoxide following short duration high intensity exercise

We investigated the time course of changes in post-exercise pulmonary diffusing capacity for carbon monoxide (DLCO), membrane diffusing capacity (DM), and pulmonary capillary blood volume (VC) in highly trained (HT), moderately trained (MT) and untrained (UT) male subjects (n = 8/group). Subjects were assigned to groups based on their aerobic capacity from a preliminary VO2max test (HT > or = 65, MT = 50-60, UT < or = 50 ml x kg(-1) x min(-1)). Resting (BASE) DLCO, DM and VC were obtained, then subjects cycled to fatigue at the highest workrate attained during the preliminary tests. Diffusion measurements were then made at 1, 2, 4, 6 and 24 h. DLCO was depressed at 1 h, lowest at 6 h and approached BASE values at 24 h in all groups. The DLCO change was paralleled by a change in VC. Alterations to VC were similar between groups except at 24 h where MT and HT subjects had returned to BASE while UT did not. DM was significantly lower than BASE at 1, 2, 4, and 6 h, and was similar between groups. The changes in DLCO post-exercise appear to be primarily due to a decrease in VC. Comparable diffusion decrements were observed in all subjects. The results of this study suggest that post-exercise alterations in DLCO, DM and VC are not related to aerobic capacity.

Ventilation and Respiratory Mechanics

During dynamic exercise, the healthy pulmonary system faces several major challenges, including decreases in mixed venous oxygen content and increases in mixed venous carbon dioxide. As such, the ventilatory demand is increased, while the rising cardiac output means that blood will have considerably less time in the pulmonary capillaries to accomplish gas exchange. Blood gas homeostasis must be accomplished by precise regulation of alveolar ventilation via medullary neural networks and sensory reflex mechanisms. It is equally important that cardiovascular and pulmonary system responses to exercise be precisely matched to the increase in metabolic requirements, and that the substantial gas transport needs of both respiratory and locomotor muscles be considered. Our article addresses each of these topics with emphasis on the healthy, young adult exercising in normoxia. We review recent evidence concerning how exercise hyperpnea influences sympathetic vasoconstrictor outflow and the effect this might have on the ability to perform muscular work. We also review sex-based differences in lung mechanics.

Inhaled salbutamol and doping control: effects of dose on urine concentrations.

Objective:The present study was designed to examine the dose-response relationship of inhaled salbutamol and its concentration in the urine while resting at various times after inhalation, and to compare these values against the current World Anti-Doping Code limits. Design:An interventional, repeated-measures design. Setting:Sport Medicine Clinic, University of British Columbia (Vancouver, Canada). Participants:Eight healthy, nonasthmatic males participated in this study (age = 28 ± 6 years, height = 179.4 ± 5.1 cm, and weight = 77.4 ± 5.4 kg). Intervention:Administration of three different doses of inhaled salbutamol (800, 400, and 200 μg) in a randomized fashion separated by at least 72 hours. Main Outcome Measurement:Urine concentration of nonsulphated salbutamol Results:Urine concentrations were highly variable between subjects and increased as dose increased, with a significant difference noted between 800 and 200 μg at 30, 60, and 120 minutes after inhalation. Urine concentrations of salbutamol peaked at 60 minutes for all doses. No samples exceeded the doping criterion of 1000 ng/mL, and the maximum value observed was 904 ng/mL. Conclusion:These results indicate that after inhalation of doses up to 800 μg, urinary concentrations of salbutamol are well below the limits used in doping control.

Dysanapsis and the resistive work of breathing during exercise in healthy men and women

We asked if the higher work of breathing (Wb) during exercise in women compared with men is explained by biological sex. We created a statistical model that accounts for both the viscoelastic and the resistive components of the total Wb and independently compares the effects of biological sex. We applied the model to esophageal pressure-derived Wb values obtained during an incremental cycle test to exhaustion. Subjects were healthy men (n = 17) and women (n = 18) with a range of maximal aerobic capacities (V̇o2 max range: men = 40-68 and women = 39-60 ml·kg(-1)·min(-1)). We also calculated the dysanapsis ratio using measures of lung recoil and forced expiratory flow as index of airway caliber. By applying the model we found that the differences in the total Wb during exercise in women are due to a higher resistive Wb rather than viscoelastic Wb. We also found that the higher resistive Wb is independently explained by biological sex. To account for the known effect of lung volumes on the dysanapsis ratio we compared the sexes with an analysis of covariance procedures and found that when vital capacity was accounted for the adjusted mean dysanapsis ratio is statistically lower in women (0.17 vs. 0.25 arbitrary units; P < 0.05). Our collective findings suggest that innate sex-based differences may exist in human airways, which result in significant male-female differences in the Wb during exercise in healthy subjects.