Publications (29)168.1 Total impact
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Article: Combined index of heart rate variability and oximetry in screening for the sleep apnoea/hypopnoea syndrome.
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ABSTRACT: Many sleep centres employ a preliminary screening test in order to reduce the number of polysomnographies required in the routine diagnosis of the sleep apnoea/hypopnoea syndrome (SAHS). We investigated the combination of heart rate and oximetry information as a means of performing this test. A retrospective study of 100 patients with suspected SAHS was made. All patients had in-hospital polysomnography on one night. We estimated the number of respiratory event-related arousals by counting the number of autonomic arousals (assessed on the basis of changes in the heart interbeat interval) that were coincident with a rise in oximetry. The hourly index of such events was denoted the "cardiac-oximetry disturbance index" (CODI). The median apnoea/hypopnoea index (AHI) was 16.5 (range 1.0-93.6) h-1. The CODI correlated significantly with the AHI (Spearman correlation coefficient rs = 0.88, P < 0.01), and the area (+/- standard error) under the receiver operating characteristic (ROC) was 0.94 +/- 0.05. Oximetry alone (based on 4% dips) was a less effective screening test (rs = 0.80, P < 0.01; area under ROC 0.83 +/- 0.06). Using 2% dips in oximetry offered comparable performance with the CODI (rs = 0.91, P < 0.01; area under ROC 0.93 +/- 0.04). The CODI was better correlated with the electroencephalograph arousal index (rs = 0.84, P < 0.01) than was oximetry (2% dips, rs = 0.57, P < 0.01). The CODI algorithm also offers an informal measure of self-validation: a large discrepancy between the number of autonomic arousals and the number of rises in oximetry indicates the presence of autonomic arousals without changes in oximetry (or vice versa). This self-validation mechanism identified several patients in this study, and may be useful in identifying sleep disruption due to chronic pain or other causes.Journal of Sleep Research 03/2003; 12(1):53-61. · 3.16 Impact Factor -
Article: The sleep apnoea/hypopnoea syndrome depresses waking vagal tone independent of sympathetic activation.
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ABSTRACT: The modest daytime hypertension and sympathetic upregulation associated with the sleep apnoea/hypopnoea syndrome (SAHS), does not explain the relatively large increased risk of cardiac morbidity and mortality in the SAHS patients population. Therefore, efferent vagal and sympathetic activity was evaluated during wakefulness in SAHS subjects and matched healthy controls, in order to determine if vagal downregulation may play a role in the aetiology of cardiac disease in the SAHS. The awake autonomic nervous system function of 15 male subjects, with mild-to-moderate SAHS was compared to that of 14 healthy controls matched for age, body mass index, gender and blood pressure. All subjects were free from comorbidity. Vagal activity was estimated from measurements of heart rate variability high frequency power (HF) and sympathetic activity was measured from urine catecholamine excretion. The %HF power was significantly (p < 0.03) reduced in SAHS patients (10+/-1.6 (mean+/-SEM)) as compared to controls (17 +/- 3). In addition, HF power correlated with the apnoea/hypopnoea index in the SAHS subjects (R = -0.592, p = 0.02). There was no statistically significant difference in the daytime excretion of nonadrenaline between control (242 +/- 30 nmol x collection(-1)) and SAHS (316 +/- 46 nmol x collection(-1)) subjects (p = 0.38). In these sleep apnoea/hypopnoea syndrome patients there was limited evidence of increased waking levels of urine catecholamines. The principal component altering waking autonomic nervous system function, in the sleep apnoea/hypopnoea syndrome subjects, was a reduced daytime efferent vagal tone.European Respiratory Journal 06/2001; 17(6):1258-66. · 5.89 Impact Factor -
Conference Proceeding: Screening for obstructive sleep apnoea based on the electrocardiogram-the computers in cardiology challenge
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ABSTRACT: The authors present a method of screening for obstructive sleep apnoea based on the electrocardiogram (ECG). The algorithm combines information from the ECG-derived respiration (EDR) signal and the RR interval tachogram. Power spectral features from the EDR signal were computed using the discrete harmonic wavelet transform, considering the power at the respiratory frequency and at frequencies below 0.1 Hz. Cycles of tachy/bradycardia (consistent with an arousal from sleep, as would be expected at the end of an episode of apnoea) were identified front the RR interval tachogram. Features were collated into minute-by-minute vectors and passed to a classifier. The algorithm correctly classified 81% of all minutes in the test database, with 29/30 patients correctly identified as apnoea or normal. Visual classification produced 92% correct classification, with all 30 patients correctComputers in Cardiology 2000; 02/2000 -
Article: Evaluation of frequency and time-frequency spectral analysis of heart rate variability as a diagnostic marker of the sleep apnoea syndrome.
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ABSTRACT: The sleep apnoea/hypopnoea syndrome (SAHS) elicits a unique heart rate rhythm that may provide the basis for an effective screening tool. The study uses the receiver operator characteristic (ROC) to assess the diagnostic potential of spectral analysis of heart rate variability (HRV) using two methods, the discrete Fourier transform (DFT) and the discrete harmonic wavelet transform (DHWT). These two methods are compared over different sleep stages and spectral frequency bands. The HRV results are subsequently compared with those of the current screening method of oximetry. For both the DFT and the DHWT, the most diagnostically accurate frequency range for HRV spectral power calculations is found to be 0.019-0.036 Hz (denoted by AB2). Using AB2, 15 min sections of non-REM sleep data in 40 subjects produce ROC areas, for the DFT, DHWT and oximetry, of 0.94, 0.97 and 0.67, respectively. In REM sleep, ROC areas are 0.78, 0.79 and 0.71, respectively. In non-REM sleep, spectral analysis of HRV appears to be a significantly better indicator of the SAHS than the current screening method of oximetry, and, in REM sleep, it is comparable with oximetry. The advantage of the DHWT over the DFT is that it produces a greater time resolution and is computationally more efficient. The DHWT does not require the precondition of stationarity or interpolation of raw HRV data.Medical & Biological Engineering & Computing 12/1999; 37(6):760-9. · 1.88 Impact Factor -
Conference Proceeding: A new application for heart rate variability: diagnosing the sleep apnoea syndrome
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ABSTRACT: The unique heart rate rhythm in the sleep apnoea/hypopnoea syndrome (SAHS) may provide the basis for an effective screening tool. This paper assesses the variability (HRV), using the Discrete Fourier Transform (DHWT). Spectral HRV results are compared to those of the current screening method of oximetry. Diagnostic indicator of the SAHS in both NREM and REM sleep. The DHWT offers advantages over the DFT in that it supplies greater time resolution and is computationally more efficientComputers in Cardiology 1998; 10/1998 -
Article: Long-term nasal intermittent positive pressure ventilation in patients with cystic fibrosis and hypercapnic respiratory failure (1991-1996).
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ABSTRACT: In patients with cystic fibrosis (CF), nasal intermittent positive pressure ventilation (NIPPV) is currently used as a short-term bridge to transplantation but its precise role has yet to be determined. Patients were offered a therapeutic trial of NIPPV when candidates for lung transplantation, with respiratory failure unresponsive to medical treatment. Twelve patients, six male of mean age of 26 +/- 1.4 years, had a trial of NIPPV. At recruitment the mean percentage predicted forced expired volume in one second (FEV1) was 15.1% +/- 1.2%, arterial carbon dioxide (PaCO2) 8.7 +/- 0.6 kPa, arterial oxygen (PaO2) with variable FiO2 7.4 +/- 0.6 kPa and arterial bicarbonate (HCO3-) 40.1 +/- 1.6 mmol l-1. Ten cases tolerated NIPPV for 1-15 months, mean 5.1 +/- 1.4 months, with subjective improvement in headache and quality of sleep. At 3 months, there was significant improvement in forced vital capacity, PaCO2 and arterial HCO3- and there was a reduction in the number of hospital inpatient days (P < 0.05). Subsequently three cases had lung transplantation, four died on the active list and three are awaiting organs. Two patients failed to tolerate NIPPV owing to abdominal bloating and increasing hypercapnia. In conclusion, NIPPV, if tolerated, was a useful adjunct in the treatment of CF patients with hypercapnic respiratory failure awaiting transplantation. Further prospective studies are required to determine the optimum time to commence NIPPV and to clarify its precise role.Respiratory Medicine 04/1998; 92(3):523-6. · 2.47 Impact Factor -
Article: Validation of British Thoracic Society guidelines for the diagnosis of the sleep apnoea/hypopnoea syndrome: can polysomnography be avoided?
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ABSTRACT: The British Thoracic Society report on the diagnosis and treatment of the sleep apnoea/hypopnoea syndrome (SAHS) suggests that, if the pulse oximetry baseline oxygen saturation is above 90%, then 15 4% oxygen desaturation/hour in bed will diagnose SAHS requiring treatment. The diagnostic outcome of applying these guidelines has been studied. One hundred patients referred to a district general hospital sleep clinic were recruited. After initial clinical assessment, overnight pulse oximetry measurements were performed, followed by full polysomnography at the regional laboratory. Sixty nine patients underwent both pulse oximetry and polysomnography. All 10 patients with more than 15 4% desaturations/hour on pulse oximetry had SAHS confirmed on polysomnography (specificity = 100%). Twenty two patients with SAHS were misdiagnosed using pulse oximetry alone (sensitivity = 31%). These patients had low apnoea scores but high hypopnoea scores. The BTS pulse oximetry criteria are highly specific when positive (specificity = 100%), but may miss patients with the SAHS who have hypopnoeic episodes which cause arousal but not significant oxygen desaturation (sensitivity = 31%). It should be emphasised that pulse oximetry alone does not always give sufficient information to discriminate between those patients with or without SAHS. Patients with "negative" pulse oximetry and symptoms of SAHS should undergo polysomnography or multi-channel recording.Thorax 10/1995; 50(9):972-5. · 6.84 Impact Factor -
Article: Does single dose salmeterol affect exercise capacity in asthmatic men?
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ABSTRACT: The aim of this study was to investigate whether the long-acting beta-agonist salmeterol affects athletic performance in patients with asthma. The effect of 50 micrograms salmeterol on the cardiorespiratory responses to a progressive maximal cycle exercise test and on endurance capacity (defined as the exercise duration at 70% maximum oxygen uptake), was compared with 200 micrograms salbutamol and a matched placebo in eight asthmatic men. Both salmeterol and salbutamol improved pre- and postexercise forced expiratory volume in one second (FEV1) for maximal and endurance exercise. Following active treatment, patients exercised from a significantly high baseline FEV1, with both salmeterol (3.58(1.16)l) (mean (SD)) and salbutamol (3.55(1.24)l) compared with placebo (3.29(1.35)l). Similar improvements preceded endurance exercise. Cardiorespiratory, haemodynamic or subjective responses to the progressive maximum exercise tests were not different with salmeterol, salbutamol or placebo, nor did endurance capacity change with any treatment modality. Blood lactate levels, after 15 min exercise, were significantly higher with salbutamol (3.64 (1.83) mM), but not with salmeterol (3.03 (1.64) mM), compared with placebo (2.95 (1.69) mM). These results demonstrate the absence of significant cardiorespiratory or metabolic effects during exercise after a single dose of salmeterol, together with a lack-of ergogenic effect, as measured by maximal or endurance exercise performance, in patients with asthma.European Respiratory Journal 12/1994; 7(11):1978-84. · 5.89 Impact Factor -
Article: Nocturnal hypoxaemia in cystic fibrosis: relationship to pulmonary function tests.
Respiratory Medicine 09/1994; 88(7):537-9. · 2.47 Impact Factor -
Article: Rates of change in peak expiratory flow and in diurnal variation in peak flow in patients recovering from acute severe asthma.
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ABSTRACT: 1. The rates of change in mean peak expiratory flow and in diurnal variation in peak flow were compared in 14 patients recovering from acute severe asthma. 2. Peak expiratory flow was measured on hospital admission, and at 6-hourly intervals for the next 3 weeks. 3. Diurnal variation in peak flow was assessed by measuring the following: amplitude (the highest minus the lowest peak expiratory flow during any given 24 h period), amplitude % mean (the highest minus the lowest peak expiratory flow during any given 24 h period divided by the mean peak expiratory flow over that period) and residual amplitude (the maximum variation about the mean peak expiratory flow during any given 24 h period). 4. Plots of diurnal variation in peak flow and peak expiratory flow against time were constructed for each patient. To enable comparison of changes in peak expiratory flow and diurnal variation in peak flow the data were transformed. 5. The rate of change for mean peak expiratory flow and for the three measures of diurnal variation in peak flow was assessed by fitting an exponential function to each set of data, and calculating the slope of the exponential curve halfway through the period of observation (10.5 days). 6. Median (range) slope for peak expiratory flow was 0.055 (0-2.57). The comparable value for amplitude was -3.15 (-1.27 to -4.22) (absolute median values compared, P = 0.0029), for amplitude % mean was -1.87 (-0.18 to -5.95) (P = 0.012) and for residual amplitude was -1.43 (-0.62 to -3.09) (P = 0.033).(ABSTRACT TRUNCATED AT 250 WORDS)Clinical Science 02/1994; 86(1):59-65. · 4.61 Impact Factor -
Article: Endurance exercise capacity in adults with cystic fibrosis.
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ABSTRACT: We have compared the maximal and endurance exercise capacities in 22 (15 male) adult cystic fibrosis (CF) patients with a resting oxygen saturation (SaO2) > or = 90%, with age and sex matched controls (CON). The maximum oxygen uptake (VO2max) and heart-rate were lower for the CF group whereas the maximum ventilation reached a higher percentage of predicted. Furthermore, for the CF group there was a relationship between the % predicted VO2max and measures of lung function, confirming a ventilatory limit to maximum exercise in patients with more severe disease and a near normal maximum exercise capacity in those with mild disease. Endurance capacity, defined as the duration of exercise at 80% of each individuals VO2max, was however similar for the two groups [CF: 22.21 (15.82) vs. CON: 24.94 (13.05) min]; despite the CF group exercising under less efficient ventilatory conditions. Endurance capacity was not related to the measurements of lung function. Of the seven CF patients desaturating at maximal exercise (SaO2 < 90%), five desaturated at a work load of 80% VO2max, whereas only one desaturated at 50% VO2max. This study confirms that with increasing severity of disease, maximal exercise capacity may be limited in adult CF patients, whereas endurance capacity (at the same relative work load) is unimpaired. Furthermore, CF patients who desaturate during a progressive maximal exercise test are likely to desaturate during constant work load exercise if the intensity is high but unlikely to do so if the intensity is low. The information from these exercise tests would be of value for prescribing individual training programmes and for evaluating the effects.Respiratory Medicine 10/1993; 87(7):541-9. · 2.47 Impact Factor -
Article: The effect of ipratropium bromide on maximal exercise capacity in asthmatic and non-asthmatic men.
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ABSTRACT: The effect of 0.5 mg nebulized ipratropium bromide (IB) on the cardio-respiratory responses to a progressive maximal cycle exercise test was compared with a matched placebo (P) in eight mild asthmatic and eight non-asthmatic men. The forced expiratory volume in l s (FEV1) in the asthmatic group was higher after ipratropium bromide both at rest [IB, mean 4.07 (SD 1.18) l versus P, 3.83 (1.29) l, P less than 0.05] and after exercise [IB, 3.64 (1.31) l versus P, 3.30 (1.40) l, P less than 0.02]. Since the percentage fall in the FEV1 after exercise was not significantly changed by ipratropium bromide [IB, -12 (11)% versus P, -16 (14)%], the improvement in the post-exercise FEV1 in the asthmatic group is attributable to the pre-exercise bronchodilatation. The resting and post-exercise FEV1 in the non-asthmatic group were also significantly higher after ipratropium bromide. However, neither group showed any differences in the cardio-respiratory, haemodynamic or subjective responses to the progressive maximum exercise test when ipratropium bromide was compared with placebo. These results demonstrate the absence of significant cardio-respiratory effects during exercise with this relatively high dose of ipratropium bromide, in patients with mild asthma and in non-asthmatic subjects. No ergogenic effect on maximal exercise performance was shown to question its use by asthmatic athletes engaged in high level competition.Respiratory Medicine 04/1992; 86(2):151-5. · 2.47 Impact Factor -
Article: Cardio-respiratory responses to exercise following treatment of acute severe asthma.
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ABSTRACT: Asthmatic patients are encouraged to adopt a normal and active life-style. However, following treatment of acute severe asthma, patients may ask for advice about taking exercise. Serial measurements of the cardio-respiratory responses to continuous work load exercise, were made in asthmatic patients convalescing following hospital treatment of an acute exacerbation. Eighteen asymptomatic patients, (seven male) aged 18-48 years, were studied. The first test was performed within 1 week of admission, when the mean (SD) peak expiratory flow rate (PEFR) was 88 (20)% predicted normal and the arterial oxygen tension (PaO2) was 13.1 (1.4) kPa. No significant differences in the mean cardio-respiratory responses, from the last minute of exercise, were found during the 4-week study. There were no significant differences in the four tests, between the resting PEFR, lowest post-exercise PEFR or % change in PEFR. Also, there were no significant differences in the pre-exercise, end of exercise and recovery (10 min after exercise) PaO2, between the four tests. However, taking the four tests as a whole, significant relationships were found between the recovery PaO2 and the lowest post-exercise PEFR, expressed in absolute terms (r = 0.515, P less than 0.001), and as a percentage of predicted normal (r = 0.533, P less than 0.001); and also between the recovery PaO2 and the % change in PEFR after exercise (r = 0.299, P less than 0.05). It is suggested that a formal exercise test should be performed in convalescent asthmatics wishing to participate in active sports. Patients with exercise-induced asthma may then be identified and treated appropriately.Respiratory Medicine 10/1991; 85(5):413-20. · 2.47 Impact Factor -
Article: Lung function and diabetes.
Respiratory Medicine 06/1991; 85(3):257-8. · 2.47 Impact Factor -
Article: The effect of sustained-release theophylline in nocturnal asthma.
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ABSTRACT: Nocturnal symptoms are common and often disabling in asthmatic subjects. Furthermore, they often persist, in spite of appropriate dosages of inhaled beta 2-agonists and topical steroids. In such a clinical situation, theophylline preparations may have a therapeutic role. This double-blind, placebo-controlled, cross-over trial was designed to evaluate the effectiveness of a twice-daily Bioavail slow-release theophylline capsule in a group of out-patient asthmatics, with a history of nocturnal and/or early morning wheeze or chest tightness. Theophylline was initially prescribed and monitored in an 'open' phase to obtain the drug dosage required to achieve a serum level in the therapeutic range of 10-20 mg/l. In the ten patients who completed the study, serum theophylline levels were stable throughout. During active treatment there was an improvement in morning peak expiratory flow rate (PEFR), and a reduction in measurements of diurnal variation. In addition, the bronchodilator response to an inhaled beta 2-agonist was preserved. Bioavail theophylline has thus been shown to be an effective agent in the management of adults with nocturnal asthma.The British journal of clinical practice 02/1991; 45(1):21-5. -
Article: Effects of exercise on gas exchange in patients recovering from acute severe asthma.
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ABSTRACT: The effect of exercise on gas exchange was studied in 17 patients (seven male and 10 female) recovering in hospital from acute severe asthma. On admission the patients (mean age 26 (SD 8) years) had a mean peak expiratory flow (PEF) of 26.8% (5.7%) predicted, a mean arterial oxygen tension (PaO2) of 8.63 (1.26) kPa, and a mean alveolar-arterial oxygen difference (A-aDO2) of 5.98 (1.34) kPa. Once resting symptoms had resolved (after 3.7 (1.6) days) patients performed a constant load exercise test (100 watts for men, 75 watts for women) on a bicycle ergometer for five minutes. PEF was measured before exercise and at five minute intervals for 30 minutes after exercise. Blood gas tensions were measured on capillary blood before, during, and 10 minutes after exercise. Treatment was not interrupted for this study. Mean PEF at rest was 87.6% (21.1%) predicted and showed no significant change after exercise. Mean PaO2 was 13.13 (1.37) kPa before exercise; it showed no significant change during exercise (13.93 (1.34) kPa) or 10 minutes after exercise (13.50 (2.15) kPa). Mean A-aDO2 also showed no change, being 1.82 (1.31) kPa before exercise, 1.79 (1.27) kPa during exercise, and 2.53 (0.93) kPa after exercise. It is concluded that moderate exercise carried out shortly after treatment for acute severe asthma is unlikely to result in worsening gas exchange during or after exercise if resting PEF, PaO2 and A-aDO2 have attained normal or near normal values.Thorax 05/1990; 45(4):262-6. · 6.84 Impact Factor -
Article: The twenty-metre shuttle-running test: a combined test for maximal oxygen uptake and exercise-induced asthma?
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ABSTRACT: A maximal multistage 'twenty-metre shuttle-running test' has already been developed to estimate maximal oxygen uptake (VO2 max). This field test requires little equipment or expertise, can be performed simultaneously by several subjects, and is widely used in physical education lessons. The present study assessed the potential for this test to provoke exercise-induced asthma in 73 schoolboys, aged 15-16 years. Measurements of the forced expiratory volume in one second (FEV1) were made at rest and 10 min after the twenty-metre shuttle-running test; exercise-induced asthma was defined as greater than a 10% fall in FEV1 after exercise. The pupils achieved 73 +/- 19 shuttles (mean +/- SD) giving a VO2 max of 47.0 +/- 5.3 ml kg-1 min-1. Exercise-induced asthma was documented in eight pupils (11%); two were known asthmatics who, despite taking pre-exercise B2 agonist treatment, had sharp falls in FEV1 (-25.4 and -25.6%); two had previously experienced occasional chest tightness or wheeze with exercise (-16.5 and -13.2% fall FEV1); but four were asymptomatic, with no previous asthmatic symptoms (-20.0, -18.2, -15.3 and -11.4% fall FEV1). This study has demonstrated the potential of the twenty-metre shuttle-running test to provoke exercise induced-asthma, and may therefore be a useful clinical test to assess for exercise-induced asthma when an estimate of VO2 max would also be helpful. Furthermore, physical education teachers should take basic precautions when using this test.(ABSTRACT TRUNCATED AT 250 WORDS)Respiratory Medicine 02/1990; 84(1):31-5. · 2.47 Impact Factor -
Article: Association between risk factors for coronary heart disease in schoolboys and adult mortality rates in the same localities.
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ABSTRACT: Risk factors for coronary heart disease were compared in fifth year boys (15-16 years old) from two schools that were chosen from localities with a fourfold difference in adult mortality from coronary heart disease. One school was in an underprivileged urban locality in the area of increased incidence of heart disease ('high risk') and the other in a semi-rural affluent locality with an incidence of heart disease similar to the national average ('low risk'). Smoking, hypertension, hypercholesterolaemia, obesity, physical fitness, and inactivity were evaluated as risk factors for coronary heart disease. Smoking, increased body fat, poor diet, and physical inactivity were found increased among pupils from the school in the high risk area compared with those in the low risk area. Lipids, maximum oxygen uptake, and hypertension were similar in both schools. The risk of coronary heart disease seems to reflect the adult mortality rates in the area. To reduce the overall incidence of coronary heart disease, health education should be directed towards prevention of smoking, improving diets, and increasing amounts of activity among school children, with special attention directed toward children in regions where there is a high mortality from coronary heart disease among adults.Archives of Disease in Childhood 02/1990; 65(1):78-83. · 2.88 Impact Factor -
Article: Effect of nebulised salbutamol on maximal exercise performance in men with mild asthma.
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ABSTRACT: The effect of 5 mg nebulised salbutamol on the cardiorespiratory responses to a progressive maximal exercise test was investigated in eight asthmatic (mean forced expiratory volume in one second (FEV1) 3.48 (1.0) litres) and eight non-asthmatic men. Exercise tests were performed on a bicycle ergometer after administration of nebulised salbutamol or matched saline placebo. In the asthmatic subjects salbutamol increased the resting FEV1 by 11%. The mean (SD) percentage fall in FEV1 after exercise did not change significantly (salbutamol 9.4 (12.8); placebo 15.0 (8.0], but because the FEV1 before exercise was increased the lowest FEV1 after exercise was also significantly higher after salbutamol than placebo (3.60 (1.13) v 2.85 (0.80) litres). Despite the improvement in FEV1 before exercise there was no significant difference in maximal workload, oxygen uptake, heart rate, or ventilation during exercise after salbutamol compared with placebo in the asthmatic patients. Tidal volume was higher at maximal exercise after salbutamol but there was no change in perception of breathlessness or exertion in the asthmatic subjects. During submaximal progressive exercise the perceived rate of exertion was reduced in the asthmatic patients and oxygen pulse was reduced in both groups owing to a small and non-significant increase in heart rate. The FEV1 and cardiorespiratory response to the progressive maximal exercise test in the non-asthmatic subjects were otherwise unchanged after salbutamol. The results suggest that 5 mg nebulised salbutamol has little effect on the cardiorespiratory responses to progressive maximal exercise in patients with mild asthma and in non-asthmatic subjects. Salbutamol in this dose may reduce the severity of exercise induced asthma, but no ergogenic effect on maximal exercise performance was shown.Thorax 12/1989; 44(11):942-7. · 6.84 Impact Factor -
Article: Blood fuel metabolites in asthma during and after progressive submaximal exercise.
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ABSTRACT: Ten male stable asthmatic subjects and 10 matched control subjects performed a progressive exercise test on a treadmill to 85% of their predicted maximum heart rate. Blood lactate, pyruvate, hydrogen ion, glucose, alanine, glycerol and total ketone body concentrations were measured at frequent intervals during and up to 60 min after exercise. Carbon dioxide production, oxygen consumption, ventilation, respiratory exchange ratio and oxygen saturation were also measured during and up to 10 min after exercise. There were no significant differences between the asthmatic and control subjects in levels of carbon dioxide production, oxygen consumption and ventilation. The respiratory exchange ratio was greater in the asthmatic subjects during recovery from exercise (P less than 0.05). No changes in oxygen saturation were observed during exercise in either group. In both asthmatic and control subjects, lactate, pyruvate, hydrogen ion, alanine and glycerol concentrations showed an increase from baseline levels, reaching maximum levels up to 10 min after exercise and returning to baseline within 1 h after exercise. Total ketone body concentrations decreased during exercise. There were no significant differences between the asthmatic and control subjects in the concentration of any metabolite over the study period. These data indicate that fuel metabolism during and after short-term progressive exercise is similar in stable asthmatic and normal subjects.Clinical Science 08/1987; 73(1):81-6. · 4.61 Impact Factor
Top co-authors
Top Journals
- Respiratory Medicine (7)
- Thorax (6)
- The Lancet (2)
- Clinical Science (2)
- European Respiratory Journal (2)
Institutions
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2001
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The University of Warwick
- School of Engineering
Warwick, ENG, United Kingdom
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1999
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Harvard University
- Department of Medicine Brigham and Women's Hospital
Boston, MA, USA
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