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J E Eldridge

Publications and source records attributed to J E Eldridge.

17 recordsLinked to original sources
PubMed1988

Computer analysis of oxygen consumption and minute ventilation for the detection of the lactate threshold.

A group of 15 normal subjects performed a maximal-exercise test on a treadmill. Arterial lactate measurements were related to oxygen consumption (VO2) in an exponential fashion (individual correlation coefficients ranged from 0.9 to 0.99). In the same subjects, minute ventilation (VE) was related to VO2 in an exponential fashion (individual correlation coefficients ranged from 0.98 to 1). There was a close correlation (r = 0.97, p less than 0.001) between the slope of the log of lactate versus VO2 and the slope of the log of VE versus VO2. A computer program for predicting the VO2 corresponding to the accumulation of arterial lactate above the resting normal value (1.3 mM), defined as the lactate threshold, is described. The program is based on the slopes of the exponential relationship between lactate and VO2 and between VE and VO2 derived in the normal subjects. The program analyses 30-second values of VO2 and VE. In 28 subjects, the reproducibility of the lactate threshold prediction was evaluated during two exercise tests 1-7 days apart. The mean predicted VO2 at the lactate threshold was 18.6 +/- 7 ml/(kg.min) during test 1 and during test 2 it was 17.9 +/- 7.3 ml/(kg.min); r = 0.91, p less than 0.001. The corresponding values for maximal VO2 were 30.4 +/- 13 ml/(kg.min) and 31 +/- 13 ml/(kg.min); r = 0.99, p less than 0.001. It is concluded that this program offers a reproducible method of determining the lactate threshold during exercise testing employing a frequently used clinical protocol.

Adult↗
PubMed1987

Comparison of nitroglycerin patches and nifedipine.

Fifteen patients with stable angina participated in a 12-week crossover study to evaluate the efficacy of nifedipine and nitroglycerin patches. There was an initial 2-week drug washout period followed by a 2-week control period when patients received no other antianginal treatment other than sublingual nitroglycerin for relief of angina episodes. At the end of the 2-week control period, exercise performance was assessed with treadmill exercise testing and measurement of oxygen consumption during the final third of the dosing interval. Myocardial perfusion was assessed using thallium scintigraphy with the injection of thallium at 85% of the maximum oxygen consumption. Patients were then randomized to nifedipine or nitroglycerin patches, and the dosage was titrated at weekly intervals according to symptomatic response. The final dose was received for at least 2 weeks. After 4 weeks, patients received the alternate medication. Maximal exercise testing and thallium scintigraphy were repeated after each drug period. Both nifedipine (mean dose, 70 mg/day) and nitroglycerin patches (mean dose, 16 cm/day) significantly reduced the frequency of angina and the consumption of sublingual nitroglycerin. Nifedipine decreased the reversible thallium defect score (49 +/- 29 vs. 28 +/- 26 U, p less than 0.01). Both drugs reduced electrocardiographic evidence of myocardial ischemia at submaximal exercise. Maximal oxygen consumption was not significantly increased by either drug when the test was done during the latter part of the dosing interval. The clinical implications of this study are that the dosage of nifedipine and nitrate patches, based on symptomatic criteria of angina frequency reduction, may not result in objective improvement in exercise performance.

Administration, Cutaneous↗
PubMed1987

Patterns of oxygen consumption during exercise testing in peripheral vascular disease.

Exercise testing on a treadmill was performed in 15 patients with peripheral vascular disease to determine the pattern of oxygen consumption during exercise. A plateau in the oxygen consumption over the final 90 s of exercise was used as a criterion for maximal effort and only 4 out of 15 (27%) obtained a plateau of oxygen consumption compared to 20 out of 26 (77%) normal subjects (chi 2 7.9, p less than 0.005). These findings may account for the limited value of exercise testing in detecting coronary artery disease in patients with peripheral vascular disease.

Adult↗
PubMed1986

Comparison of acute hemodynamic effects of nitroglycerin versus diltiazem and combined acute effects of both drugs in angina pectoris.

Fifteen patients with exertional angina underwent hemodynamic monitoring and measurement of cardiac output during a control treadmill exercise test. They were then randomized to receive sustained-release nitroglycerin, 13 mg (group I) or placebo (group II). Repeat exercise testing revealed that in group I, both maximal oxygen consumption and cardiac output increased significantly. In group II neither maximal oxygen consumption nor cardiac output increased significantly. All patients then received diltiazem, 60 mg, and repeat testing was carried out 1 hour later. In group I maximal oxygen consumption and cardiac output were higher than control, but were no higher than after nitroglycerin. In group II, maximal oxygen consumption increased significantly, but the increase in cardiac output was not significant. Thus, sustained-release nitroglycerin, 13 mg, or diltiazem, 60 mg, both improve exercise performance, but the combination does not improve exercise performance to an extent greater than either drug alone.

Aged↗
PubMed1986

Computerized detection of the lactate threshold in coronary artery disease.

A computer program for identifying oxygen consumption at the lactate threshold was evaluated by expired gas analysis during treadmill exercise testing in 15 patients with prior myocardial infarction. There was a strong correlation (r = 0.85, p less than 0.001) between computer-identified oxygen consumption (14.1 +/- 4.6 ml/kg/min) and the oxygen consumption (14.6 +/- 4.8 ml/kg/min) corresponding to an increase of arterial lactate level to above the normal value at rest (1.3 mM). The computer program was superior to previously described visual methods for identifying the ventilatory threshold.

Adult↗