Biomedical subjects

M B Effron

Publications and source records attributed to M B Effron.

21 records · Page 2Linked to original sources

PubMed1983

Elastic properties of the human chest during cardiopulmonary resuscitation.

Sternal displacement during CPR was measured in 11 adults and 2 manikins (Recording Resusci Anne) while the chest was compressed with variable maximum pulse compression force at a rate of 60/min with compression duration of 0.5-0.6 sec. In 10 patients, the pulsatile sternal elastic characteristic can be satisfactorily described with a 2nd degree polynomial F = beta Ds + gamma D2s, where beta = 54.9 +/- 29.4 (mean +/- SD) N/cm is the pulsatile initial elasticity and gamma = 10.8 +/- 4.1 N/cm2 is the posterior resiliency. The sternal characteristics of manikins were linear F = kDs with high elasticity constants, k = 131 and 142 N/cm. Therefore, the manikins tested differ significantly in elasticity characteristics from the human chest during resuscitation. In general, the manikin: (1) has markedly greater stiffness at the onset of compression, and (2) maintains a linear stiffness throughout the usual range of displacement, rather than becoming stiffer with greater chest displacement.

Adolescent↗

PubMed1978

Effect of tris(hydroxymethyl)aminomethane on ischemic myocardium.

Intracellular acidosis may depress myocardial function and metabolism during ischemia. In the present study, the function and metabolism of a globally ischemic, isovolumic cat left ventricle preparation, perfused with oxygenated Krebs-Ringer biocarbonate solution, was examined. Addition of tris(hydroxymethyl)-aminomethane (Tris) (15 mM) to the perfusate at physiologic pH and PCO2 increased performance during ischemia to a greater extent and for a longer period than low PCO2 )15 mmHg), alkalotic (pH, 7.8) perfusate and a control sucrose perfusate. Under nonischemic conditions the inotropic effect of Tris was only briefly greater than sucrose perfusate. The inotropic effect of Tris during ischemia did not appear to depend on changes in coronary flow, oxygen consumption, sodium concentration, perfusate osmolality, or catecholamine release. During ischemia, lactate production was unchanged with Tris, but increased with low PCO2-alkalosis. Tissue levels of ATP and creatine phosphate for control ischemic hearts did not differ from Tris-perfused or low PCO2-alkalosis hearts. Thus, Tris appears to exert an inotropic effect that is more prominent in ischemic than nonischemic myocardium. The results are consistent with the possibility that Tris acts as an intracellular buffer to increase the efficiency of energy production and/or utilization during ischemia.

Adenosine Triphosphate↗

PubMedDate not supplied

Exercise training combined with antihypertensive drug therapy. Effects on lipids, blood pressure, and left ventricular mass.

We studied exercise training combined with the use of antihypertensive drugs and examined the following questions. (1) Are there additive antihypertensive benefits with exercise and drug therapy combined? (2) Does drug therapy limit exercise-induced lipid improvements? (3) Does exercise that includes weight training and walking/jogging affect the left ventricle? Fifty-two hypertensive men were randomly assigned, double-blind, to diltiazem hydrochloride, sustained release (360 mg daily), propranolol hydrochloride (240 mg daily), or placebo and exercised three times per week for 10 weeks. Baseline blood pressure (145/97 mm Hg) fell after training (131/84 mm Hg) in all groups. Exercise decreased total and low-density lipoprotein cholesterol levels in all groups. Increases in the levels of high-density lipoprotein cholesterol were similar in placebo and diltiazem groups, whereas the propranolol group changed in an opposite direction. In all groups, left ventricular mass increased with training, while diastolic function was unchanged. We conclude that (1) drug therapy provided no additive benefit to the antihypertensive effects of exercise, (2) propranolol limited improvements in high-density lipoprotein cholesterol, and (3) exercise did not adversely affect the left ventricle.

Adolescent↗