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Biomedical subjects

P F Walter

Publications and source records attributed to P F Walter.

33 records · Page 2Linked to original sources
PubMed1981

Paradoxical rise in left ventricular filling pressure in the dog during positive end-expiratory pressure ventilation. A reversed Bernheim effect.

Controversy exists whether positive end-expiratory pressure (PEEP) ventilation lowers cardiac output by reducing left ventricular preload, or by a combination of mechanisms. Sixteen open-chest dogs were instrumented for measurement of left and right ventricular pressure, aortic flow, and left ventricular dimensions. With the pericardium intact, PEEP caused the interventricular septum to bulge toward the left ventricular chamber, increased right and left ventricular end-diastolic pressures, but decreased the average of the three left ventricular dimensions. When right ventricular filling pressure was suddenly reduced, the interventricular septum moved back toward the right ventricle, and left ventricular filling pressure fell. With the pericardium removed, PEEP was associated with a decrease in all three left ventricular end-diastolic dimensions but no significant change in left ventricular filling pressure. Although several indices of contractility were decreased during PEEP, all returned to baseline values when left ventricular preload was normalized during PEEP by a rapid infusion of heparinized blood into the left atrium. In conclusion, PEEP decreases preload and significantly alters the shape and compliance of the left ventricle with the pericardium intact. With the pericardium removed, PEEP produces proportional decreased in major and minor axis dimensions, does not appear to affect left ventricular contractility independent of preload, and alters left ventricular compliance to only a small degree.

Animals↗
PubMed1980

Transcutaneous method of measuring Doppler cardiac output--I. Comparison of transcutaneous and juxta-aortic Doppler velocity signals with catheter and cuff electromagnetic flowmeter measurements in closed and open chest dogs.

Cardiac output values obtained by thermodilution technique in 20 closed and open chest dogs were compared with values obtained by multiplying the integral of Doppler systolic velocity signals of aortic flow in 1 minute by the cross-sectional area of the aortic root. Doppler velocity signals were measured either from immediately outside the proximal aortic wall or from outside the chest wall during (1) the baseline state, (2) after 500 ml of hemorrhage, and (3) after reinfusion, (4) after administration of propranolol, and (5) during infusion of dopamine. In addition, Doppler "stroke volume" waveforms were compared with those obtained by electromagnetic flowmeter. Results showed a close similarity between Doppler signals and electromagnetic waveforms, and a close correlatin between Doppler and thermodilution values for cardiac output except at heart rates exceeding 160 beats/min. The studies showed the transcutaneous Doppler method of measuring cardiac output to be an accurate and reliable technique with application to clinical heart disease.

Animals↗
PubMed1980

Transcutaneous Doppler method of measuring cardiac output--II. Noninvasive measurement by transcutaneous Doppler aortic blood velocity integration and M mode echocardiography.

In 15 patients with acute myocardial infarction (group I) and in 14 patients undergoing routine cardiac catheterization (group II) cardiac output values obtained by multiplying the 1 minute sum of the systolic integral of aortic blood flow velocity by the average systolic diameter of the aortic root were compared with values obtained with the thermodilution and Fick methods, respetively. Patients in group I were studied under various hemodynamic conditions, whereas those in group II were studied in the baseline state conditions, whereas those in group II were studied in the baseline state only. In group I, the correlation between the two methods was excellent (r values ranged from 0.96 to 0.99) except in one severely anemic patient whose Doppler signals were noisy, but at heart rates exceeding 150 beats/min it was not as good. In group II, the correlatin between the two methods was r = 0.96 with a standard error of the estimate of 0.226 liter. The Doppler method is totally noninvasive and is useful for monitoring changes in cardiac output in patients with acute myocardial infarction.

Adult↗
PubMed1979

Ligation of the superior vena cava for recurrent pulmonary emboli.

A patient with polycythemia vera developed chronic thrombosis of the superior vena cava and had life-threatening pulmonary emboli despite anticoagulation and chemotherapy for the blood dyscrasia. After angiographic evaluation, the superior vena cava was ligated cephalad to the azygous vein. There have been no further clinical embolic episodes nor adverse effects over a three-year period of observation.

Humans↗
PubMed1978

Carotid sinus hypersensitivity and syncope.

Hyperactivity of the carotid sinus reflex is common in older men. However, an unequivocal diagnosis of carotid sinus syncope is difficult to establish because the symptoms are nonspecific, and both hyperactivity of the carotid sinus reflex and syncope are common. Twenty-one men were evaluated for episodes of lightheadedness or syncope, or both, associated with a hypersensitive carotid sinus reflex. Seventeen patients had the cardioinhibitory type, two the vasodepressor type and two both the cardioinhibitory and vasodepressor types. Patients with the cardioinhibitory type benefited from the insertion of a permanent pacemaker if they had multiple episodes of syncope. A history of syncope associated with some event capable of stimulating the carotid sinus was also helpful in selecting patients for pacemaker treatment. The combination of the cardioinhibitory and vasodepressor types may be missed unless carotid sinus stimulation is repeated after the administration of atropine. The results of electrophysiologic studies in 17 patients with the cardioinhibitory type suggest that intrinsic sinus nodal dysfunction is not the major cause for asystole after carotid sinus stimulation.

Aged↗
PubMedDate not supplied

Reduce hospital costs with admissions and operating room scheduling systems.

This paper is the authors' attempt to summarize major aspects of an admissions and OR scheduling systems. The admissions scheduling system can help achieve a stabilization of elective OR procedures and potential increase in utilization of ORs; however, a computer-aided-OR scheduling system is needed to meet the special needs of the OR scheduling process. Thus, combined use of an admissions and OR scheduling system appears to provide the best opportunity for reducing hospital costs as well as providing superior service.

Admitting Department, Hospital↗