The Calculation of Cardiac Output and Effective Peripheral Resistance From Blood Pressure Measurements With an Appendix on the Size of the Aorta in Man

Bazett, H. C.; Cotton, FS; Laplace, Louis B.; Scott, John C.

doi:10.1152/ajplegacy.1935.113.2.312

“…Having ascertained that waves H, I, and J were in phase with the body's period, as they almost always are, the altitude of I was corrected by subtracting from it 40 per cent of the altitude of H; and J by subtracting (2) which are reproduced in a more convenient form in Table I, or read directly from his Figure 3 (2).…”

Section: Techniquementioning

confidence: 99%

Ballistocardiogram. Ii. Normal Standards, Abnormalities Commonly Found in Diseases of the Heart and Circulation, and Their Significance 1

Starr

¹

,

Schroeder²

1940

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The Ballistocardiograph (1), a modern adaptation of an old idea, consists of a table suspended from the ceiling on wires and braced to prevent motion in any but the longitudinal direction. Motion in this direction, opposed by a strong steel spring, is magnified about 8,000 times and photographed.When a subject lies on the table he is not conscious of its motion but the records obtained are characteristic and reproducible. Figures 1, 3, and 4 give typical examples. The chief forces producing this motion have been identified as the recoil from the ejection of blood from the heart, the impact of the blood striking the arch of the aorta and the curve of the pulmonary artery and, of less importance, the recoil from the systemic blood accelerated feetward when the aortic arch has been passed. The resultant of these forces is not perfectly reproduced in the record, the chief difficulty being due to the physical properties of body tissues which vibrate for a brief instant after receiving a single blow. These aftervibrations warp the descending part of the record but they have a much smaller effect on the ascending part, and from this part reliable data can be secured.Evidence has been presented (1) that the size of the initial waves, I and J, is related to the cardiac output and that the form of the ballistic curve is determined by the shape of the curve of blood velocity in the great vessels. These conceptions lead one to expect that, when the circulation is feeble, the ballistocardiogram will be of low amplitude and, when the heart is weak, the form of the ballistic record will be altered.Therefore, we believe that this simple method will permit the easy identification of patients with 1 The completion of this work was assisted by a grant from the Penrose Fund of the American Philosophical Society.abnormal circulations and will also provide evidence of cardiac health or disease of a type which has no counterpart in the ordinary clinical tests.To realize this expectation it was first necessary to determine the normal standards. To this end over 200 healthy persons from 20 to 84 years of age were examined and standards of normality have been obtained from the results. Ballistocardiograms have also been secured on over 400 patients and this experience has permitted description and analysis of the more common variations from the normal. TECHNIQUEAt first all tests were performed with the subject under conditions of basal metabolic rate, but we soon abandoned this in favor of a test made after 15 or 30 minutes' rest and not less than 2 hours after a meal. The chief reason for this change was convenience but we justified it by several arguments. It is true that the basal ballistocardiogram is of somewhat lower amplitude than that obtained in the resting condition described, but the differences found in pathological conditions are so much larger that confusion seems most unlikely. One can point to an analogy with the blood pressure. The basal blood pressure is considerably lower than the value obtained at other times but the...

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“…The values found were entered in the fol- =334i(2frIdt+frJdt)A 4C. (2) Both formulae for cardiac output give very similar results. We started by preferring the altitude formula as simpler but have gradually come to prefer the area method.…”

Section: Techniquementioning

confidence: 99%

Ballistocardiogram. II. Normal standards, abnormalities commonly found in diseases of the heart and circulation, and their significance

1940

American Heart Journal

0

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The Ballistocardiograph (1), a modern adaptation of an old idea, consists of a table suspended from the ceiling on wires and braced to prevent motion in any but the longitudinal direction. Motion in this direction, opposed by a strong steel spring, is magnified about 8,000 times and photographed.When a subject lies on the table he is not conscious of its motion but the records obtained are characteristic and reproducible. Figures 1, 3, and 4 give typical examples. The chief forces producing this motion have been identified as the recoil from the ejection of blood from the heart, the impact of the blood striking the arch of the aorta and the curve of the pulmonary artery and, of less importance, the recoil from the systemic blood accelerated feetward when the aortic arch has been passed. The resultant of these forces is not perfectly reproduced in the record, the chief difficulty being due to the physical properties of body tissues which vibrate for a brief instant after receiving a single blow. These aftervibrations warp the descending part of the record but they have a much smaller effect on the ascending part, and from this part reliable data can be secured.Evidence has been presented (1) that the size of the initial waves, I and J, is related to the cardiac output and that the form of the ballistic curve is determined by the shape of the curve of blood velocity in the great vessels. These conceptions lead one to expect that, when the circulation is feeble, the ballistocardiogram will be of low amplitude and, when the heart is weak, the form of the ballistic record will be altered.Therefore, we believe that this simple method will permit the easy identification of patients with 1 The completion of this work was assisted by a grant from the Penrose Fund of the American Philosophical Society.abnormal circulations and will also provide evidence of cardiac health or disease of a type which has no counterpart in the ordinary clinical tests.To realize this expectation it was first necessary to determine the normal standards. To this end over 200 healthy persons from 20 to 84 years of age were examined and standards of normality have been obtained from the results. Ballistocardiograms have also been secured on over 400 patients and this experience has permitted description and analysis of the more common variations from the normal. TECHNIQUEAt first all tests were performed with the subject under conditions of basal metabolic rate, but we soon abandoned this in favor of a test made after 15 or 30 minutes' rest and not less than 2 hours after a meal. The chief reason for this change was convenience but we justified it by several arguments. It is true that the basal ballistocardiogram is of somewhat lower amplitude than that obtained in the resting condition described, but the differences found in pathological conditions are so much larger that confusion seems most unlikely. One can point to an analogy with the blood pressure. The basal blood pressure is considerably lower than the value obtained at other times but the...

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“…It is a representative of the group of drugs whose action is similar to that which follows stimulation of parasympathetic nerves. Of the 6 patients, 4 were subject to peripheral vascular disease and previously had had relief of pain after the drug. All of them had improved to the extent of freedom from pain when these tests were made.…”

Section: Ephedrinementioning

confidence: 99%

“…The left ventricular work was calculated as described before (3). The peripheral resistance was calculated from the formula used by Bazett et al (4).…”

mentioning

confidence: 99%

A clinical study of the action of 10 commonly used drugs on cardiac output, work, and size; on respiration, on metabolic rate, and on the electrocardiogram

1938

American Heart Journal

0

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The possession of a technique which permitted rapid estimations of cardiac output and which, demanding no intelligent cooperation, seemed especially suitable for use on ward patients, has permitted an extensive study on the action of common drugs on the heart and circulation in clinical conditions. This study contains about 450 estimations of cardiac output performed on 85 patients.Coincidentally with these estimations the action of drugs on pulse rate, on blood pressure, on respiratory rate and volume, and on metabolic rate was observed. Orthodiagrams and electrocardiograms were secured also. Therefore, certain parts of our study dealt with effects already well known.The results of such estimations have permitted the calculation of heart work, of peripheral resistance, of arteriovenous oxygen difference, and of the ratio of heart work to heart size, the latter a factor of decisive importance in our conception of cardiac stimulation and depression. Therefore our study demonstrates the effect of drugs on these functions also.Most of the drugs selected are commonly used in cases of cardiac and circulatory disease. We have studied the actions of digitalis, epinephrine, ephedrine, caffeine, theophylline, carbaminoylcholine, sodium nitrite, nitroglycerine, pitressin, quinidine, morphine and strychnine. We have studied the effects of drugs in those clinical conditions in which physicians are accustomed to employ them.But when suitable cases were not available the effects were studied in other conditions. Almost without exception our results support the general conceptions of drug action derived from animal experiments. PROCEDUREAll estimations were performed in the morning. The patients received no food after their evening meal and no water after midnight. They were taken from the ward in bed or in a wheel chair. An electrocardiogram and an orthodiagram were obtained first. Then the subjects lay down for at least 45 minutes. Duplicate estimations of cardiac output and metabolism were then made, together with repeated determinations of pulse rate, blood pressure, respiratory rate and volume.If the study concerned a rapidly acting drug, this was administered soon after the control estimations. The patient was watched until evidence of the drug's action became manifest objectively. Duplicate estimations of cardiac output and metabolism were then made, the purpose being to make these determinations at the height of action. Orthodiagrams and electrocardiograms were secured immediately afterward. Cardiac output was estimated by the method of Starr and Gamble (1), the analyses being performed by the katharometer method of Donal, Gamble and Shaw (2). Metabolism was estimated from samples of expired air drawn from a mixing bottle containing a fan.Respiratory volume was obtained by reading the spirometer at frequent intervals. Respiratory rate was counted repeatedly during the period of observations. It is well known that subjects breathing from a spirometer under 3 mm. H,O negative pressure, and through valves, tend to breathe...

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The Calculation of Cardiac Output and Effective Peripheral Resistance From Blood Pressure Measurements With an Appendix on the Size of the Aorta in Man

Cited by 52 publications

References 0 publications

Ballistocardiogram. Ii. Normal Standards, Abnormalities Commonly Found in Diseases of the Heart and Circulation, and Their Significance 1

Ballistocardiogram. Ii. Normal Standards, Abnormalities Commonly Found in Diseases of the Heart and Circulation, and Their Significance 1

Ballistocardiogram. II. Normal standards, abnormalities commonly found in diseases of the heart and circulation, and their significance

A clinical study of the action of 10 commonly used drugs on cardiac output, work, and size; on respiration, on metabolic rate, and on the electrocardiogram

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