Thoracic Blood Volume Research Articles

Intrathoracic airstream temperatures during acute expansions of thoracic blood volume.

1. To determine the validity of employing intrathoracic heat flux as a reflection of changes in bronchial blood flow, we used a thermal probe to record airstream temperatures within the tracheobronchial tree in five normal and five asthmatic subjects during isocapnic hyperventilation challenges with and without inflation of the lower limb bladders of a pressure suit. 2. During hyperpnoea, airstream temperatures fell progressively in both subject groups. When blood volume was acutely shifted from the legs into the thorax via anti-shock trousers, airstream temperatures within the tracheobronchial tree rose and were significantly higher than the temperature recorded during hyperpnoea alone. In the normal subjects, once hyperpnoea ceased, the rate of airway re-warming was similar whether or not the anti-shock trousers were inflated. In the asthmatic subjects, however, shifting blood into the thorax attenuated the obstructive response to hyperpnoea and slowed the rate of re-warming. 3. These data demonstrate that changes in airway blood volume are reflected in fluctuations in intrathoracic heat exchange and that disruption of the end hyperpnoea thermal gradient attenuates the airway obstruction that follows hyperpnoea. Since the bronchial blood supply is the major source of heat to the airways, this circulation may play an important role in thermally induced asthma.

Redistribution of regional and organ blood volume and effect on cardiac function in relation to upright exercise intensity in healthy human subjects.

To determine the effect of relative exercise intensity on organ blood volume and its relation to cardiac function, changes in relative blood volume and cardiac function were monitored with radionuclide techniques in 14 healthy volunteers. After labeling the subject's red cells with technetium 99m, we acquired data at rest, zero-load cycling, and at 50%, 75%, and 100% of maximal oxygen uptake. From rest to zero-load cycling, leg blood volume decreased 32 +/- 2% (mean +/- SEM), whereas relative end-diastolic blood volume increased 9.6 +/- 1.2%, and lung blood volume increased 18 +/- 2%, suggesting that the lungs may act as a blood volume buffer during periods of acutely increased venous return. With relative increasing exercise, leg blood volume stabilized, and then the blood volume in the abdominal organs decreased, further augmenting cardiopulmonary blood volume; leg blood volume and abdominal blood volume decreased by 23 +/- 2% and 19 +/- 2% from baseline, respectively, whereas thoracic blood volume increased 38 +/- 4%. In the abdomen, large decreases in blood volume were observed in the spleen (46 +/- 2%), kidney (24 +/- 4%), and liver (18 +/- 4%). In contrast, lung blood volume increased 50 +/- 4%, with the upper lung fields increasing more than the lower. Blood sampling revealed an increase in the hematocrit level by 4.3 +/- 0.4 units at peak exercise that paralleled the decrease in splenic blood volume (r2 = -0.64, p less than 0.001), suggesting a role for the spleen in augmenting cardiovascular performance by the release of concentrated red blood cells into general circulation. We conclude that upright exercise results in marked blood volume shifts from the legs and abdominal organs to the heart and lungs in a dynamic process correlating closely with oxygen consumption.

Volume quantification of chest wall motion in dogs.

We employed high-speed multisliced X-ray-computed tomography to determine the relative volume contributions of rib cage (delta Vrc) and diaphragmatic motion (delta Vdi) to tidal volume (VT) during spontaneous breathing in 6 anesthetized dogs lying supine. Mean values were 40 +/- 6% (SE) for delta Vrc and 62 +/- 8% of VT for delta Vdi. The difference between VT and changes in thoracic cavity volume was taken to represent a change in thoracic blood volume (2 +/- 3% of VT). To estimate how much of delta Vrc was caused by diaphragmatic contraction and how much of delta Vdi was caused by rib cage motion, delta Vrc and delta Vdi were determined during bilateral stimulation of the C5-C6 phrenic nerve roots in the apneic dog and again during spontaneous breathing after phrenicotomy. Thoracic cavity volume (Vth) measured during hypocapnic apnea was consistently larger than Vth at end expiration, suggesting that relaxation of expiratory muscles contributed significantly to both delta Vrc and delta Vdi during spontaneous inspiration. Phrenic nerve stimulation did not contribute to delta Vrc, suggesting that diaphragmatic contraction had no net expanding action on the rib cage above the zone of apposition. Spontaneous breathing after phrenicotomy resulted in small and inconsistent diaphragmatic displacement (8 +/- 4% of VT). We conclude that the diaphragm does not drive the rib cage to inflate the lungs and that rib cage motion does not significantly affect diaphragmatic position during spontaneous breathing in anesthetized dogs lying supine.

Measurement of lung tissue mass, thoracic blood and interstitial volumes by transmission/emission scanning using [99mTc]pertechnetate.

1. We have developed a method for non-invasive measurement of lung tissue mass, thoracic blood and interstitial volumes by a combination of transmission and emission scanning with technetium isotope (99mTc). 2. In a lung model we demonstrated that emission counts could be successfully corrected for attenuation with data obtained by transmission scanning, despite an uneven distribution of radioactivity and attenuation in the model. 3. In dogs we compared regional transthoracic tissue thickness, measured by transmission scanning, and regional 'thickness' of blood measured by transmission/emission scanning with direct gravimetric measurements made post mortem. Scanning and direct measurements correlated significantly. 4. In man we used a [99mTc]pertechnetate (99mTcO4) flood source to obtain antero-posterior transmission scans with a gamma-camera. The thickness of attenuating tissue was estimated in each pixel. Scans were obtained of thoracic blood (by labelling erythrocytes with 99mTcO4) and of interstitium (with 99mTc-labelled diethylenetriaminepenta-acetic acid and subtraction of the blood image). We used a computer program to correct the emission scans for attenuation using the transmission scan derived tissue thickness, pixel by pixel. Finally we took a lateral chest radiograph to estimate chest wall thickness. 5. In normal man lung tissue thickness at hilar level was 3.1 +/- 0.5 cm (n = 8). Thoracic blood thickness increased from the apex downwards in the upright lung, being 1.2 +/- 0.1 cm at the hilar level and 2.0 +/- 0.3 cm at the lung base. Interstitial thickness was 0.8 +/- 0.3 cm at the hilum and 0.85 +/- 0.2 at the base. These values compare well with data in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of age on hemodynamic response to graded postural stress in normal men.

We studied the hemodynamic effect of graded gravity (g) increments from 10 degrees headdown (-0.17 g) to 70 degrees headup (+0.94 g) tilt on young (20 to 29 years), middle-aged (40 to 49 years) and older (60 to 69 years), healthy men. Thoracic blood volume and ventricular stroke volume decreased linearly with increasing g levels. Heart rates and diastolic pressures increased, but only at the higher g levels; however, the increases were significantly less in the 60- to 69-year-old men. The results indicate that thoracic blood volume and ventricular stroke volume are remarkably gravity dependent over the entire tilt range in all groups, the lesser heart rate and diastolic pressure responses in older participants are significant circulatory handicaps and may contribute to the increased incidence of postural hypotension in elderly persons, the sharp rise in vascular resistance at lower +g levels (when arterial pressure is unchanged) suggests that cardiopulmonary reflexes play an important role in human circulatory adjustment to the headup posture.

Determination of Central Blood Volume and Extravascular Lung Water

In patients undergoing thoracic surgery central blood volume is subject to large variations and extravascular lung water may change critically due to fluid shifts. Therefore, an accurate monitoring of these parameters, in particular under perioperative conditions, seems to be desirable. This study describes an improved method for the measurement of intrathoracic volumes. Experiments were carried our in 9 mongrel dogs under piritramide-N2O anesthesia. In order to produce low cardiac output in combination with uneven distribution of perfusion, measurements were performed under base line conditions and after postural changes. Indicators (cold and indocyanine green dye) were injected into the v. cava and indicator kinetics were recorded from the pulmonary artery and aorta using thermistor-fiberoptic catheters. The transport functions of cold and dye were computed from the corresponding pairs of dilution curves. From the transport functions, the mean transit times of the intravascular (dye) and diffusible (cold) indicator were determined. Central blood volume and extravascular lung thermal volume were calculated from the mean transit times and a thermodilution cardiac output. Under base line conditions, central blood volume was 15.3 +/- 2.5 ml/kg body weight. In orthostasis, a significant and reversible reduction to 11.6 +/- 2.4 ml/kg body weight was found. Cardiac output fell significantly from 3.3 +/- 0.5 to 2.4 +/- 1.1. l/min. In contrast, the slight decrease of extravascular lung thermal volume was not statistically significant. It is concluded that the method presented is sensitive enough to detect even small changes of central blood volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive Estimates of Cardiac Performance during and Early after Single and Repeated Passive Upright Tilt in Normal Men: Volume Dependency of Systolic Time Intervals and Maximum Velocity of Transthoracic Impedance Changes

The combination of electrocardiography, impedance cardiography and phonocardiography allows to measure systolic time intervals and maximum velocity of transthoracic impedance changes (dZ/dt(max)) as estimates of (changes in) cardiac performance. Such assessment was performed in 35 normal male subjects undergoing single gradual passive upright tilting and 11 subjects undergoing repeated upright tilting. During tilting a cardio-acceleratory and vasopressor response is evident in compensation for the largely reduced stroke volume as a consequence of the reduced preload. During upright tilting, heart rate-corrected preejection pressure (PEP) was prolonged, heart rate-corrected left ventricular ejection time (LVET) was shortened and PEP/LVET was increased, and dZ/dt(max) and related parameters were reduced during upright tilting. These changes most likely reflect the preload dependency of these parameters even to such an extent that they could not reflect net inotropic changes related to the increased adrenergic activity during tilting. During the first 10 min after upright tilt, dZ/dt(max) and estimated stroke volume were increased versus supine baseline prior to tilt, whereas the return of the estimated thoracic blood volume back to baseline was delayed. This was associated with a relative bradycardia and slight reduction in diastolic blood pressure. These changes reached their maximum on average 3–4 min after the supine position was resumed. This enhanced cardiac pump performance early after tilt, suggested by dZ/dt(max) and related parameters, was not associated with corresponding changes in systolic time intervals. Although both systolic time intervals and dZ/dt(max) may be volumedependent, dZ/dt(max) and related parameters may offer additional information on cardiac performance not derivable from systolic time intervals.

Intrathoracic Platelet Accumulation in the Guinea-Pig Induced by Intravenous Administration of Arachidonic Acid - Effect of Cyclooxygenase and Thromboxane Synthetase Inhibitors

Intravenous administration of arachidonic acid to guinea-pigs caused a dose-related, rapid accumulation of 51Cr-labelled platelets in the thorax. Inhibitors of cyclooxygenase inhibited the platelet accumulation, induced by arachidonic acid (30 mg/kg), at doses which did not alter the thoracic blood volume (as measured by 131I-labelled human albumin). Thromboxane synthetase inhibitors had different effects on platelet accumulation depending on the dose. CGS 12970 (3 mg/kg) and N(1-carboxyheptyl) imidazole (100 mg/kg) reduced platelet accumulation. High doses of CGS 12970 and CGS 13080 caused an apparent enhancement of platelet accumulation which was associated with pooling of blood in the thorax, as measured by either 131I-labelled human albumin or 51Cr-labelled erythrocytes. This increase in thoracic blood volume was abolished if the guinea-pigs were also pretreated with diclofenac (1 mg/kg) in addition to the thromboxane synthetase inhibitor. Increases in thoracic blood volume were also obtained following infusions of PGI2 but not PGD2 or PGE2.

Halothane anesthesia attenuates cardiopulmonary baroreflex control of peripheral resistance in humans.

The effects of halothane anesthesia on cardiopulmonary (low pressure) baroreflex control of peripheral resistance were studied in 10 ASA class I young men. Graded (-5, -7.5, -10, -12.5 mmHg) lower body negative pressure (LBNP) was used to produce progressive decreases in thoracic blood volume and central venous pressure. These stimuli activate reflexes from cardiopulmonary baroreceptors. Volunteers were studied while awake and during 1 MAC (0.75%) and 1.25 MAC (0.93%) halothane anesthesia. Hetastarch (6%) in 0.9% normal saline was infused into patients before baseline recordings were initiated. Blood pressure, stroke volume, cardiac output, and systemic and forearm vascular resistance decreased and forearm blood flow increased during halothane anesthesia. In awake subjects, LBNP did not alter heart rate or blood pressure, but stroke volume and cardiac output decreased. Blood pressure was maintained by cardiopulmonary baroreflex-mediated increases in peripheral resistance. In anesthetized subjects, decreases in stroke volume and cardiac output during LBNP were similar to awake responses, however, hypotension occurred because reflex resistance increases were markedly attenuated. The authors conclude that halothane anesthesia blunts cardiopulmonary baroreflex resistance responses provoked by mild decreases in thoracic blood volume in humans.

Effect of age and coronary heart disease on the circulatory responses to graded lower body negative pressure.

Previous reports have demonstrated that haemodynamic responses to various autonomic stresses such as head-up tilt, Valsalva's manoeuvre, face immersion, cold pressor, and static exercise are altered with increasing age and cardiac disease. In the present investigation, we compared the responses of 20 to 27 year old and 50 to 59 year old healthy men and 50 to 59 year old ambulatory coronary heart disease patients to graded lower body negative pressure (LBNP). Noninvasive methods including transthoracic impedance cardiography and venous occlusion plethysmography were used to monitor changes in stroke index, thoracic blood volume and vascular resistance. The tachycardia and stroke index decline of the older men and cardiac patients at higher levels of LBNP were similar but less than those of the younger men; we also noted greater increases in forearm and total peripheral resistance during LBNP in the two older groups than in the younger group. However, the decreases in thoracic blood volume were less in the two older groups at the higher levels of LBNP indicating that older subjects had been subjected to a lesser stress. These differences in thoracic blood volume displacement may be due to a decreased peripheral venous compliance in older subjects. When we compared responses to similar decreases in thoracic blood volume, the heart rate and stroke index changes were similar in the three groups but the exaggerated forearm vascular resistance and total peripheral resistance index increases in the older groups persisted. Our data suggest: (1) the decreased haemodynamic response to postural stress previously reported in older subjects and cardiac patients is due at least in part to a lesser peripheral sequestration of blood in the older individuals; (2) the lesser heart rate and stroke index responses in coronary heart disease patients to diminished preload stress may be due primarily to normal aging; and (3) the greater increases in peripheral vascular resistance in the two older groups during LBNP may be a function of the higher baseline resistance levels in these older subjects.

Mechanical properties of the lungs during acclimatization to altitude.

Mechanical properties of the lung were studied in nine healthy lowlanders during a 6-day sojourn at an altitude of 3,457 m. In comparison to sea-level values, it was found at altitude that 1) lung volumes measured by plethysmography including total lung capacity, vital capacity, and functional residual capacity (FRC) presented small changes not exceeding 300 ml; 2) static and dynamic lung compliances were not modified but static pressure-volume curves of lungs were shifted progressively to the left (the decrease in lung elastic recoil averaged about 2 cmH2O on days 4-6); and 3) maximal midexpiratory flow, forced expiratory volume in 1 s, and maximal expiratory and inspiratory flows were increased and, conversely, airways and pulmonary flow resistances were decreased on most days at altitude. The unchanged FRC in the face of a decreased lung recoil may be explained by an increase in thoracic blood volume at altitude, but other possible mechanisms are discussed. The decrease in resistances and increase in maximal flows may be partly explained by the decreased air density at altitude, but another contributing factor such as a bronchodilatation is also suggested. It is proposed that changes in lung mechanics at altitude may account for some of the changes in the pattern of breathing and mouth occlusion pressure (P0.1) observed during acclimatization of lowlanders to altitude.

Effects of beta-adrenoceptor antagonists on central haemodynamics in essential hypertension.

British Journal of Clinical PharmacologyVolume 13, Issue S2 p. 269S-278S Free Access Effects of beta-adrenoceptor antagonists on central haemodynamics in essential hypertension. H Tsukiyama, H TsukiyamaSearch for more papers by this authorK Otsuka, K OtsukaSearch for more papers by this authorK Higuma, K HigumaSearch for more papers by this author H Tsukiyama, H TsukiyamaSearch for more papers by this authorK Otsuka, K OtsukaSearch for more papers by this authorK Higuma, K HigumaSearch for more papers by this author First published: April 1982 https://doi.org/10.1111/j.1365-2125.1982.tb01924.xCitations: 29AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References ADLER-GRASCHINSKY, E. & LANGER, S.Z. (1975). Possible role of a β-adrenoceptor in the regulation of noradrenaline release by nerve stimulation through a positive feedback mechanism. Br. J. Pharmac., 53, 43– 50. ATKINS, J.M., MITCHELL, H.C. & PETTINGER, W.A. (1977). Increased pulmonary vascular resistance with systemic hypertension. Am. J. Cardiol., 39, 802– 807. ATTERHÖG, J.-H., DUNER, H. & PERNOW, B. (1976). Experience with pindolol, a β-receptor blocker, in the treatment of hypertension. Am. J. Med., 60, 872– 876. BRITTAIN, P.T. & LEVY, G.P. (1976). A review of the animal pharmacology of labetalol, a combined α- and β-adrenoceptor blocking drug. Br. J. clin. Pharmac., 3, (Suppl. 3), 681– 694. GOTO, K., HIRANO, A. & HIRAKAWA, S. (1981). Noninvasive estimation of the human pulmonary blood volume with gamma camera and RI-angiocardiography. Jap. circ. J., 45, 113– 119. LONDON, G.M., SAFAR, M.E., WEISS, Y.A. & SIMON, Ch.A. (1978). Total effective compliance of the vascular bed in essential hypertension. Am. Heart J., 95, 325– 330. METZNER, W., GOLDBERG, H. & LICHTENSTEIN, S. (1976). Effect of thoracic blood volume changes on steady state cardiac output. Circ. Res., 38, 255– 261. PARKER, H., WEBER, P.M., VAN DYKE, D.C., DAVIES, H., STEELE, P. & SULLIVAN, R. (1974). Evaluation of central circulatory dynamics with the radionuclide angiogram. In Cardiovascular nuclear medicine, pp 67– 100. Saint Louis: C.V. Mosby. PRICHARD, B.N.C. & GILLAM, R.M. (1964). Use of propranolol (Inderal) in treatment of hypertension. Br. med. J., 2, 725– 727. TARAZI, R.C. & DUNSTAN, H.P. (1972). β-adrenergic blockade in hypertension. Practical and theoretical implications of long-term haemodynamic variations. Am. J. Cardiol., 29, 633– 640. WEINBERGER, M.H., AOI, W. & HENRY, D.P. (1975). Direct effect of β-adrenergic stimulation on renin release by the rat kidney slice in vitro. Circ. Res. 37, 318– 324. Citing Literature Volume13, IssueS2April 1982Pages 269S-278S ReferencesRelatedInformation

Direct and reflex effects of nitroglycerin on the blood volume distribution, evaluated by regional weighing in the cat.

The effects of nitroglycerin on the blood volume distribution were studied with a method of regional weighing in the anaesthetized cat. An i.v. bolus injection of nitroglycerin produced a dose-dependent decrease in arterial pressure accompanying a decrease in the thoracic blood volume. The latter change was associated with blood volume increases principally in the abdomen, and slightly in the hindquarters. Elimination of the cardiovascular reflex effects by carotid sinus denervation and cervical vagotomy signficantly enhanced and prolonged the following changes: the hypotension, the decrease in thoracic blood volume and the volume pooling in the abdomen. The magnitude of increase in hindquarters blood volume was not significantly affected by the denervation procedures, but the duration was much prolonged. The results indicate that the major site of nitroglycerin-induced venous pooling is in the splanchnic circulation. The peripheral venous pooling is produced at the expense of a decrease in the central or pulmonary blood volume. The secondary reflex adjustments tend to minimize the direct effects of nitroglycerin on the blood pressure and blood volume distribution.

Changes in transthoracic electrical impedance during submaximal treadmill exercise in patients with ischemic heart disease—A preliminary report

Twenty normal subjects and 32 patients with ischemic heart disease (IHD) were subjected to submaximal treadmill exercise. The mean transthoracic electrical impedance (TEI) was measured with a tetrapolar lead system and the changes were correlated to the extent of ST depression observed on an on-line digital computer. Six subjects of pre-excitation syndrome with "false" ST depression were also studied. The normal subjects did not show a significant change of TEI during exercise. The patients with IHD showed a steady and significant decrease in TEI, correlating with the extent of ST depression. Recovery was slow after the cessation of exercise. The subjects with false ST changes showed no decrease of TEI. The changes were more profound in subjects who developed anginal pain during the test. These findings are attributed to an increase in the thoracic blood volume and pulmonary extravascular water due to transient left ventricular dysfunction in angina.

Endocrine responses in long-duration manned space flight

The bioassay of body fluids experiment is designed to evaluate the biochemical adaption resulting from extended exposure to space flight environment by identifying changes in hormonal and associated fluid and electrolyte parameters reflected in the blood and urine of the participating crewmen. The combined stresses of space flight include weightlessness, acceleration, confinement, restraint, long-term maintenance of high levels of performance, and possible desynchronosis. Endocrine measurements to assess the physiological cost of these stresses have been considered from two aspects. Fluid and electrolyte balance have been correlated with weight loss, changes in the excretion of aldosterone and vasopressin and fluid compartments. The second area involves the estimation of the physiological cost of maintaining a given level of performance during space flight by analysis of urinary catecholamines and cortisol. Inter-individual variability was demonstrated in most experimental indices measured; however, constant patterns have emerged which include: body weight change; increases in plasma renin activity; elevations in urinary catecholamines, ADH, aldosterone and cortisol concentrations. Plasma cortisol decreases in immediate postflight samples with subsequent increase in 24-hour urines. The measured changes are consistent with the prediction that a relative increase in thoracic blood volume upon transition to the zero-gravity environment is interpretated as a true volume expansion resulting in an osmotic diuresis. This diuresis in association with other factors ultimately results in a reduction in intravascular volume, leading to an increase in renin and a secondary aldosteronism. Once these compensatory mechanisms are effective in reestablishing positive water balance, the crewmen are considered to be essentially adapted to the null-gravity environment. Although the physiological cost of this adaptation must reflect the electrolyte deficit and perhaps other factors, it is assumed that the compensated state is adequate for the demands of the environment; however, this new homeostatic set is not believed to be without physiological cost and could, except with proper precautions, reduce the functional reserve of exposed individuals.

Age-related changes in the mechanics of the aorta and pulmonary artery of man.

Age-related changes in the mechanics of the aorta and pulmonary artery of man.

Pulmonary and circulatory adjustments determining the limits of depths in breathhold diving.

Data on pulmonary gas exchange were collected in breathhold dives to 90 feet in a tank and in open-sea breathhold dives to depths of 217.5 and 225 feet. Thoracic blood volume displacements were measured at depths of 25, 50, 90, and 130 feet, by use of the impedance plethysmograph. The open-sea dives were carried out with an average speed of descent of 3.95 feet per second and an average rate of ascent of 3.50 feet per second. End-dive alveolar oxygen tensions did not fall below 36 millimeters of mercury, while alveolar carbon dioxide tension did not rise above 40 millimeters of mercury except in one case. These findings indicate that for diver Croft, who has unusual lung capacity, neither hypoxia nor hypercapnia determined the depth limits under those conditions. At depths of 90 and 130 feet blood was forced into the thorax, amounting to 1047 and 850 milliliters respectively.

Pressure-volume curves of systemic and pulmonary circuit.

ARTICLESPressure-volume curves of systemic and pulmonary circuitJC Harlan, EE Smith, and TQ RichardsonJC Harlan, EE Smith, and TQ RichardsonPublished Online:01 Dec 1967https://doi.org/10.1152/ajplegacy.1967.213.6.1499MoreSectionsPDF (934 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByCardiovascular Responses During Sepsis1 April 2021A novel framework of circulatory equilibriumKazunori Uemura, Masaru Sugimachi, Toru Kawada, Atsunori Kamiya, Yintie Jin, Koji Kashihara, and Kenji Sunagawa1 June 2004 | American Journal of Physiology-Heart and Circulatory Physiology, Vol. 286, No. 6Static filling pressure in patients during induced ventricular fibrillationJ. D. Schipke, G. Heusch, A. P. Sanii, E. Gams, and J. Winter1 December 2003 | American Journal of Physiology-Heart and Circulatory Physiology, Vol. 285, No. 6Effects of Periodic Obstructive Apneas on Venous Return in Closed-chest DogsAmerican Review of Respiratory Disease, Vol. 148, No. 2Effects of Positive End-expiratory Pressure on the Gradient for Venous ReturnAmerican Review of Respiratory Disease, Vol. 143, No. 1Skeletal Muscle Blood Flow and Venous Capacitance in Patients with Severe Sepsis and Systemic HypoperfusionChest, Vol. 96, No. 2Theoretical effects of fluid infusions during cardiopulmonary resuscitation as demonstrated in a computer model of the circulationResuscitation, Vol. 15, No. 2Mean systemic filling pressure as a characteristic pressure for venous returnPfl�gers Archiv European Journal of Physiology, Vol. 405, No. 3Venous System: Physiology of the Capacitance Vessels1 January 2011Cardiovascular Adjustments to Gravitational Stress1 January 2011Changes in plasma renin activity and haemodynamics during vasodilator therapy in conscious dogs with myocardial infarction or chronic volume overloadEuropean Journal of Clinical Investigation, Vol. 13, No. 4Control of blood volume21 June 2005Changes in Control of Renin Release in Congestive Heart Failure in Dogs: Response to Acute and Chronic Vasodilator Therapy3 July 2009 | Clinical and Experimental Hypertension. Part A: Theory and Practice, Vol. 4, No. 4-5Increased effective vascular compliance and venous pooling of intravascular volume during sustained venodilation in conscious dogsBasic Research in Cardiology, Vol. 76, No. 6A two-compartment model of systemic circulation: Influence of transmural pressureAnnals of Biomedical Engineering, Vol. 9, No. 4Circulatory Correlates: Vascular Impedance, Resistance, and Capacity1 January 2011Effects of nitroprusside on venous return and central blood volume in the absence and presence of acute heart failure.Circulation, Vol. 61, No. 2Reflex vascular capacity reduction in the dog.Circulation Research, Vol. 39, No. 5Effect of thoracic blood volume changes on steady state cardiac output.Circulation Research, Vol. 38, No. 4Control of cardiac output by regional blood flow distributionAnnals of Biomedical Engineering, Vol. 2, No. 2Reflex Venoconstriction and Capacity Vessel Pressure-Volume Relationships in DogsCirculation Research, Vol. 34, No. 3Total Systemic Vascular Compliance Measured as Incremental Volume-Pressure RatioCirculation Research, Vol. 28, No. 2 More from this issue > Volume 213Issue 6December 1967Pages 1499-1503 Copyright & PermissionsCopyright © 1967 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1967.213.6.1499PubMed6075751History Published online 1 December 1967 Published in print 1 December 1967 Metrics

Pulmonary circulation in the aged.

Pulmonary circulation in the aged.

The mechanism of cardiovascular action of nitroglycerine: An example of integrated response during the unsteady state

The effects of nitroglycerine on phasic pressure, flow and myocardial oxygen tension were measured in anesthetized spontaneously breathing dogs. As aortic pressure fell, cardiac output increased from 10 to 55 per cent for half to three and a half minutes, then fell 10 to 25 per cent below control levels as the diastolic pressure recovered. Prolonged increases in flow depended upon adequate thoracic blood volume, sympathetic tonus and release of pressor amines. Under conditions most closely resembling those in man, measurements in dogs indicated a rise in left ventricular external work of as much as 25 per cent. Despite this additional load, myocardial oxygen tension increased. In contrast, when venous return was compromised both external work and myocardial oxygen tension fell. Indirect evidence is presented which suggests that qualitatively similar changes take place in patients with coronary artery disease. We conclude that nitroglycerine relieves ischemia by enhancing oxygen delivery rather than by altering load. Changes in chemical and/or mechanical efficiency may also play a role. The determinants of nitroglycerine responses are analyzed and the therapeutic implications briefly discussed.