Total Body O2 Consumption Research Articles

The choice of the intravenous fluid influences the tolerance of acute normovolemic anemia in anesthetized domestic pigs

IntroductionThe correction of hypovolemia with acellular fluids results in acute normovolemic anemia. Whether the choice of the infusion fluid has an impact on the maintenance of oxygen (O2) supply during acute normovolemic anemia has not been investigated so far.MethodsThirty-six anesthetized and mechanically ventilated pigs were hemodiluted to their physiological limit of anemia tolerance, reflected by the individual critical hemoglobin concentration (Hbcrit). Hbcrit was defined as the Hb-concentration corresponding with the onset of supply-dependency of total body O2-consumption (VO2). The hemodilution protocol was randomly performed with either tetrastarch (6% HES 130/0.4, TS-group, n = 9), gelatin (3.5% urea-crosslinked polygeline, GEL-group, n = 9), hetastarch (6% HES 450/0.7, HS-group, n = 9) or Ringer's solution (RS-group, n = 9). The primary endpoint was the dimension of Hbcrit, secondary endpoints were parameters of central hemodynamics, O2 transport and tissue oxygenation.ResultsIn each animal, normovolemia was maintained throughout the protocol. Hbcrit was met at 3.7 ± 0.6 g/dl (RS), 3.0 ± 0.6 g/dl (HS P < 0.05 vs. RS), 2.7 ± 0.6 g/dl (GEL, P < 0.05 vs. RS) and 2.1 ± 0.4 g/dl (TS, P < 0.05 vs. GEL, HS and RS). Hemodilution with RS resulted in a significant increase of extravascular lung water index (EVLWI) and a decrease of arterial oxygen partial pressure (paO2), and O2 extraction ratio was increased, when animals of the TS-, GEL- and HS-groups met their individual Hbcrit.ConclusionsThe choice of the intravenous fluid has an impact on the tolerance of acute normovolemic anemia induced by acellular volume replacement. Third-generation tetrastarch preparations (e.g., HES 130/0.4) appear most advantageous regarding maintenance of tissue oxygenation during progressive anemia. The underlying mechanism includes a lower degree of extravasation and favourable effects on microcirculatory function.

Abstract 4: Resuscitation with Adenocaine and Magnesium Reduces Fluid Requirement and Improves Cardiac Function Following 72% Blood Loss in the Pig

Introduction: Fluid therapy following severe hemorrhagic shock triggers ischemia-reperfusion (I/R) injury and multi-organ dysfunction. The combination of adenocaine (adenosine and lidocaine), and Mg2+ (ALM) has been shown to stabilize cardiac function and hemodynamics after myocardial I/R. Hypothesis: ALM in 7.5%NaCl at resuscitation: 1) reduces fluid requirements during permissive hypotension and 2) improves post-resuscitation cardiac function. Methods: Pigs (38kg) were randomized to: Sham (n=5), Sham + ALM (n=5), hemorrhage (n=11), and hemorrhage + ALM (n=9). Animals were subjected to pressure controlled hemorrhage at a target MAP of 35mmHg. After 90 min Ringers acetate and 20ml 7.5% NaCl ± ALM (Adenosine 0.23 mg/kg; Lidocaine 0.64 mg/kg; Mg2+ 0.4 mg/kg) was infused to maintain a target MAP of 50 mmHg (permissive hypotension). After 30min 75% of the shed blood was re-infused ± ALM (Adenosine 0.82 mg/kg; Lidocaine 1.66 mg/kg) and the pigs were observed for 6 hrs. Cardiac function was evaluated by pressure-volume (P-V) analysis. Results: In the ALM group 40% less fluid was required to maintain a MAP of 50mmHg for 30min (hemorrhage: 41.5ml/kg CI: 27.7-61.8 vs. ALM: 24.7ml/kg CI:19.4-31.5*). During permissive hypotension 7.5% NaCl ALM significantly increased end-systolic pressure by 27% (hemorrhage: 70 mmHg ± 3 vs. ALM: 89 mmHg ± 9*) and cardiac contractility by 64% (dP/dtmax) (hemorrhage: 2622 mmHg/sec ± 331 vs. ALM: 4301 mmHg/sec ± 262*). Treatment with ALM at blood infusion reduced whole body O2 consumption by 27% lasting 30 min into infusion (group difference p&lt;0.05). In addition, systolic function after blood reinfusion, evaluated by the end-systolic P-V relationship and preload recruitable stroke work, was significantly improved in ALM vs. hemorrhage. Furthermore, ALM enhanced relaxation (dP/dtmin) during reperfusion (hemorrhage: -1578 mmHg/sec ± 103 vs. ALM -2178 mmHg/sec ± 189*). Conclusion: 7.5% NaCl ALM reduced fluid requirements by 40% during permissive hypotension, improved cardiac function and reduced total body O2 consumption following severe hemorrhage. Administration of ALM is effective in minimizing fluid requirements and I/R injury following hemorrhage. (* p&lt;0.05)

Digitalis therapy for patients in clinical heart failure.

The most commonly used preparation of digitalis is digoxin, which is obtained from the leaves of Digitalis lanata , a common flowering plant called “foxglove.” The words digitalis and digoxin in this article are used interchangeably. An exhaustive review published in 19961 cited a large number of references and had detailed data and descriptions of a large number of studies and all early trials. The present article summarizes those data but focuses on and emphasizes data collected since that time. These have been described in detail previously1 and are briefly summarized. ### Inotropic Effects The inotropic effects have been documented in the isolated papillary muscles and in the normal hearts of animals and humans. The inotropic action occurs in both ventricles and in both atria. In the normal heart and in those with coronary artery disease and normal left ventricular (LV) systolic function, with digitalis the LV function curve is moved upward and to the left.1 As a result, LV end-diastolic pressure and LV end-diastolic and end-systolic volumes are reduced, and there is an increase of LV ejection fraction (LVEF).1 ### Patients With Heart Failure In patients with heart failure (HF), digoxin slows the ventricular rate (1) in sinus rhythm because of an improvement in HF and withdrawal of sympathetic stimulation and (2) in atrial fibrillation by increasing parasympathetic tone. The combination of digoxin and carvedilol is superior to digoxin or carvedilol alone.2 ### Peripheral Vessels In normal subjects given intravenous ouabain, there is arterial and venous vasocontriction.3 The vasoconstriction is obviated by administering digoxin slowly over a period of 15 to 20 minutes1; moreover, the vasoconstriction lasts up to 30 minutes. The seminal study of Mason and Braunwald3 showed that in HF, the effects are different. Digitalis produces an increase of blood flow, a decrease of vascular resistance, venodilation, and a …

Development and Initial in Vivo Testing of a New Hydraulic Drive System (Paedipump) for Circulatory Support in Infants

The main limitation in the use of circulatory support in children is the lack of an adequate system with regard to size and pumping capacity. Recently, two pneumatically driven ventricular support systems with low volume chambers for use in a pediatric population became available. We have developed a hydraulic drive system with an advantageous exact control of the stroke volume. The system enables two different modes of operation: the full-empty and the filled-empty modes. In both cases the ventricle is empty at the end of systole. This new system was tested in experimental animals (6 pigs, body weight 9.5-14.0 kg) with normal and reduced left ventricular function (MAP<45 mmHg). A 25 ml ventricle (HIA-Medos) was implanted. The full-empty and the filled-empty mode used led to a significant load reduction, both in animals with normal and impaired cardiac function. Plasma lactate levels, pH-values and total body O2-consumption were in the normal range during circulatory support indicating adequate organ perfusion. Results showed that sufficient ventricular support was achieved during all pumping modes due to the possibility of controlling and modifying the stroke volume of the hydraulically driven support system employed according to necessity. This is a promising feature for its future application in infants with congenital or acquired heart diseases.

Effects of dobutamine versus insulin on cardiac performance, myocardial oxygen demand, and total body metabolism after coronary artery bypass grafting

The purpose was to study whether the hemodynamic benefit of a catabolic catecholamine (dobutamine) induces a certain oxygen cost for the myocardial energy demand and whether this effect would be less pronounced if an anabolic intervention, such as the administration of insulin, was used. A prospective and randomized study. A university hospital. Investigation of two comparable groups of cardiac patients. The interventions were postoperative infusions of dobutamine, 7 micrograms/kg/min, and of insulin, 1.5 U/kg/h, respectively, over a period of 30 minutes. The effects of the interventions were measured using parameters relating to cardiac work and myocardial oxygen demand. Moreover, parameters relating to total body metabolism were also recorded. In the dobutamine group, cardiac index (CI) and left ventricular stroke work index (LVSWI) increased significantly (p < 0.05) during therapy by 30% and 40%, respectively. Cardiac effort index (CEI) and tension time index (TTI) also increased (p < 0.05) during therapy by 41% and 30%, respectively. However, in the insulin group, CI and LVSWI also increased (p < 0.01 and p < 0.05) during therapy, although to a lesser extent (16% and 14%), but CEI and TTI did not change at all during therapy. Total body CO2 production (VCO2) and O2 consumption (VO2) in the dobutamine group increased (p < 0.05) during therapy by 9% and 11%, respectively, whereas in the insulin group only CO2 production increased (p < 0.05) by 13%. O2 consumption remained unchanged in this group. It is concluded that dobutamine as well as insulin administration increase cardiac performance. However, in contrast to dobutamine, insulin does not appear to increase myocardial oxygen demand. Therefore, the anabolic insulin administration may represent a more economic pattern of energy-consuming hemodynamic intervention than does the catabolic catecholamine administration.

Na+,K+-ATPase IS REGULATED BY GLUCOCORTICOIDS IN AN AGE AND TISSUE DEPENDENT MANNER

The adaptation of newborn mammals to extrauterine life is conditioned by increased expression of enzymes that are of importance for specialized tissue function. In the rat, maturation is accelerated around birth in the lung and around weaning in the kidney. The Na+, K+-ATPase enzyme is responsible for the active transport of ions across the membrane of each cell at the expense of 30% of total body O2 consumption. We have reported that in the infant rat renal cortex, glucocorticoids (GC) rapidly increases the abundance of the Na+, K+-ATPase mRNA, suggesting a direct transcriptional regulation. We have now compared the effect of a single injection of betamethasone, a synthetic highly specific GC, on the abundance of mRNA for the catalytic α and the regulatory β subunits in lung and kidney from fetal, infant and young rats. In the kidney the most prominent effects on the a mRNA was found at 10 days of age (5.3±0.9 fold). A significant increase was also found in 20-day-old rats (1.6±0.2 fold), but no effect was found in fetal and 5-day-old rats. In the lung the most prominent effect was found around birth, but no effect on α mRNA was found at 10 and 20 days. In the kidney there was a coordinate increase in α and β mRNA subunits, while in the lung, the β subunit was stimulated alone, in 10- and 20-day-old rats. Conclusion. GC induction of Na+, K+-ATPase genes is age- and tissue dependent. The GC sensitive period coincides with the physiological need for organ maturation.

Dynamic exercise in senescent beagles: oxygen consumption and hemodynamic responses.

Seven senescent beagles and seven younger mature beagles were studied at rest, as well as during maximal and submaximal exercise on a motor-driven treadmill. Maximal exercise capacity was significantly (P less than 0.05) reduced, and maximal total body O2 consumption (VO2 max) was 31% lower in senescent beagles. VO2 was also significantly reduced in old dogs, when directly compared at the same relative workloads in old and younger mature dogs. However, VO2 was very similar in both groups during each of the absolute levels of directly comparable exercise. The observed age-related reduction in VO2 max was associated with a significant 25% reduction in maximal cardiac output (CO) in senescent beagles, and with an 11% reduction in maximal arteriovenous O2 difference. CO was also significantly reduced in old dogs at the same relative levels of submaximal exercise evaluated. Combined effects of reductions in stroke volume and in heart rate both contributed to the observed reductions in CO observed in senescent dogs during maximal exercise, as well as during relative levels of submaximal exercise. However, CO responses at each absolute level of submaximal exercise were similar in senescent and younger mature beagles, and the relationship between CO and VO2 was also similar in both groups. Increases in stroke volume significantly contributed to observed increases in CO beginning at the same relative level of exercise in both old and young dogs. Results of this study demonstrate that significant age-related changes in VO2max and in other associated hemodynamic parameters occur during maximal exercise. Many of these changes are also apparent when relative levels of submaximal exercise are directly compared in senescent and in younger mature beagles. However, most hemodynamic responses during absolute levels of exercise are similar in both groups, unless these parameters reflect the relative workload performed, indicating that these responses are appropriate for each absolute level of work that can be performed in the senescent dogs.

Cardiovascular effects of dobutamine during exercise in dogs.

To test the hypothesis that stimulation of adrenergic receptors in the heart is maximal during maximal exercise, and to determine whether generalized stimulation of adrenergic receptors during strenuous exercise produces significant alterations in the normal regional distribution of blood flow that occurs during exercise, we evaluated the cardiovascular effects of the infusion of dobutamine (40 micrograms.kg-1.min-1) in mongrel dogs during treadmill running. During maximal exercise, the dobutamine infusion resulted in a significant (P less than 0.05) increase in heart rate. Exercise capacity, total body O2 consumption (VO2), and maximal arteriovenous O2 difference, however, each were reduced during the infusion of this drug. A concomitant reduction in maximal blood flow to locomotive skeletal muscle occurred. The infusion of dobutamine also resulted in an increase in heart rate at a strenuous level of submaximal exercise. However, unlike during maximal exercise, VO2 was unchanged. Blood flow to locomotive skeletal muscle increased, and there was a concomitant reduction in arteriovenous O2 difference. Blood flow reductions that normally occur in splanchnic circulations during strenuous and during maximal exercise were generally somewhat attenuated during the infusion of this drug. Thus, dobutamine, a sympathomimetic agent, produces significant cardiovascular effects when infused in high doses during exercise. Our results demonstrate that beta-adrenergic receptor reserve exists in the heart during maximal exercise in dogs. In addition, the peripheral responses that occur during the infusion of the drug provide additional evidence that different degrees of adrenergic receptor reserve normally appear to be present within different regional circulations during strenuous and during maximal exercise.

Adaptation of the left ventricle to exercise-induced hypertrophy.

Cardiac functional and structural adaptations to exercise-induced hypertrophy were studied in 68 pigs. Pigs were exercise trained on a treadmill for 10 wk. Sequential measurements were made of cardiac dimensions, [left ventricular end-diastolic diameter (EDD), changes in diameter (delta D%), wall thickness (WTh), wall thickening (WTh%), left ventricular pressure (LVP), time derivative of pressure (dP/dt), stroke volume, total body O2 consumption (VO2), blood gases, and systemic hemodynamics] at rest and during moderate and severe exercise. Postmortem studies included morphometric measurements of capillary density, arteriolar density, mitochondria, and myofibrils. All of the exercise-trained pigs showed significant increases in aerobic capacity. Maximum O2 consumption (VO2 max) increased by 37.5% in group 1 (moderate exercise training) and 34% in group 3 (heavy exercise training). Cardiac hypertrophy ranged from less than 15% in a group (n = 8) subjected to moderate exercise training to greater than 30% in a group (n = 11) subjected to heavy exercise training. Before training, exercise was characterized by a decreasing EDD during progressive exercise; this was reversed after exercise training. Stroke volume and end-diastolic volumes during exercise showed a highly significant increase after exercise training and hypertrophy. Morphometric measurements showed that mitochondria and cell membranes increased with increasing myocyte growth in all exercise groups, but there was only a partially compensated adaptation of capillary proliferation. Arteriolar number and length increased in all exercise groups. Intrinsic contractility as measured by delta D%, WTh%, or left ventricular dP/dt did not increase with exercise training and in some instances decreased. Therefore, left ventricular adaptation to strenuous exercise in the pig heart is primarily one of changes in left ventricular dimensions and a compensated hypertrophy. Exercise-induced increases in EDD and stroke volume can be accounted for by decreases in peripheral resistance and increased cardiac dimensions.

Neurohumoral and cardiopulmonary response to sustained submaximal exercise in the dog.

Neurohumoral, cardiovascular, and respiratory parameters were evaluated during sustained submaximal exercise (3.2 km/h, 15 degrees elevation) in normal adult mongrel dogs. At the level of activity achieved (fivefold elevation of total body O2 consumption and threefold elevation of cardiac output), significant (P less than 0.05) increases in plasma norepinephrine and epinephrine concentration (from 150 +/- 23 to 341 +/- 35 and from 127 +/- 27 to 222 +/- 31 pg/ml, respectively) were present, as well as smaller but significant increases in plasma renin activity and plasma aldosterone concentration (from 2.2 +/- 0.3 to 3.1 +/- 0.6 ng X ml-1 X h-1 and from 98 +/- 8 to 130 +/- 6 pg/ml, respectively). Plasma arginine vasopressin increased variably and insignificantly. The cardiovascular response (heart rate, systemic arterial and pulmonary arterial pressures, left ventricular filling pressure, and calculated total peripheral and pulmonary arteriolar resistance) closely paralleled that of human subjects. Increased hemoglobin concentration was induced by exercise in the dogs. The ventilatory response of the animals was characterized by respiratory alkalosis. These data suggest similarities between canine and human subjects in norepinephrine, plasma renin activity, and plasma aldosterone responses to submaximal exercise. Apparent species differences during submaximal exertion include greater alterations of plasma epinephrine concentration and a respiratory alkalosis in dogs.

Effect of methylene blue on cardiac output response to exercise in dogs.

To determine whether the increase in cardiac output during mild to moderate exercise is related to an increase in the tissue redox potential, we compared the responses of cardiac output, total body oxygen consumption, and arterial blood lactate-to-pyruvate ratio (a measure of NADH/NAD) to treadmill exercise between dogs treated with normal saline and those treated with a hydrogen acceptor, new methylene blue. Normal saline was infused into the left atrium in the first group of dogs at a rate of 0.38 ml/min throughout the treadmill exercise (2.5 mph and 5.0 mph on a 6% incline, each for 20 min). In the second group, methylene blue was administered as a loading dose (4 mg/kg) before exercise, followed by a continuous infusion (0.15 mg X kg-1 X min-1) throughout exercise. A similar infusion of methylene blue was given to a third group of dogs without exercise; it reduced the arterial lactate-to-pyruvate ratio from 6.70 +/- 0.35 to 4.12 +/- 0.27 but had no or little effects on cardiac output, heart rate, arterial pressure, and left ventricular dP/dt and (dP/dt)/P. Treadmill exercise doubled cardiac output and increased total body O2 consumption three- to fourfold in the first two groups but increased arterial blood lactate-to-pyruvate ratio only in group 1 (6.0 +/- 0.54 to 9.97 +/- 0.91). The relationship between cardiac output and total body O2 consumption was unaffected by the simultaneous administration of methylene blue during exercise. Groups 1 and 2 also did not differ in their heart rate, left ventricular dP/dt and (dP/dt)/P, and plasma catecholamine responses to exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

The Hemodynamic Consequences of High-dose Methohexital Anesthesia in Humans

The hemodynamic, electroencephalographic (EEG), and metabolic effects of a high-dose methohexital anesthetic were examined in eight neurosurgical patients. The patients were studied at rest and at 15-min intervals during a 60-min infusion of the drug, given at a rate of 0.40 mg . kg-1 . min-1 (total dose 24 mg/kg). Ventilation was controlled with oxygen:air (FIO2 = 0.50), and fluid was infused at a rate sufficient to maintain pulmonary capillary wedge (PCW) pressures at control values (8 +/- 2 mmHg, mean +/- SD). Serum methohexital concentrations increased progressively, reaching values of 11.7 +/- 2.9 micrograms/ml at t = 30 min and 18.1 +/- 10.8 micrograms/ml at t = 60 min. Characteristic barbiturate-induced EEG changes were noted, with isoelectricity achieved at t = 28 +/- 13 min. Methohexital infusion resulted in significant reductions in arterial pressure (84% of control at t = 60 min), systemic vascular resistances (83% of control at t = 60 min), right and left ventricular stroke work indices (65% and 68% of control, respectively at t = 60 min), and total body O2 consumption (76% of control at t = 60 min). In addition, a progressive dose-related decrease in stroke volume index was noted (50.1 +/- 90 ml X beat-1 X m-2 at t = 0, 40.1 +/- 10.2 ml X beat-1 X m-2 at t = 60 [80% of control]). This occurred in spite of unchanged ventricular filling pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of increased myocardial contractility during sodium acetate infusion in humans

To analyze the reported effects of acetate on left ventricular (LV) contractility during dialysis, LV function was studied before and after a 20-min sodium acetate (Na Ac) infusion (0.06 mmoles X kg-1 X min-1) in seven patients with heart rate (HR) controlled by atrial pacing. Angiographically determined LV volumes and LV pressures were used to calculate the LV function indices. A plasma acetate concentration of 3.13 +/- 1.05 (SD) mmoles X liter-1 induced an increase in cardiac index from 3.8 +/- 0.6 to 4.4 +/- 0.6 (SD) liter X min-1 X m-2 (P less than 0.01) and a rise in total body O2 consumption from 7.47 +/- 1.28 to 8.67 +/- 1.66 mmoles X min-1 X m-2 (P less than 0.05); there was no alteration of the volume elastic constant, of the end diastolic stress, and of the end systolic stress. There was an increase of the ejection fraction from 0.44 +/- 0.10 to 0.51 +/- 0.09 (P less than 0.01), the maximum velocity of shortening (Vmax, sec-1) from 1.37 +/- 0.25 to 1.55 +/- 0.28 (P less than 0.05), and of the end systolic stress-end systolic volume ratio (g X cm-2 X ml-1) from 2.99 +/- 0.76 to 3.40 +/- 0.98 (P less than 0.01). Hence, the enhancement of these indices was not the consequence of any alteration of HR, preload, or afterload.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of free fatty acids on oxygen consumption in man: the free fatty acid hypothesis.

The effect on total body O2 consumption of induced changes in plasma free fatty acids (FFA) was studied in sixteen healthy men. In the first group (n = 5) plasma FFA was augmented by intravenous infusion of a triglyceride emulsion and heparin, increasing FFA from 0.522±0.11 to 3.025±0.357 mmol/l without any change in total O2 consumption or in the respiratory quotient. A similar supply of triglyceride emulsion and heparin was given to the second group (n = 6) during continuous infusion of isoproterenol. Isoproterenol alone increased FFA and O2 consumption. However, O2 consumption was further increased by an average of 21.1 ml/min˙m2 (P<0.005) during exogenous supply of FFA, augmenting plasma FFA from 0.753 ±0.093 to 2.195 ±0.309 mmol/l. The respiratory quotient decreased from 0.85 ±0.04 to 0.79 ±0.04 (P<0.05). In the third group (n = 5) the effect of isoproterenol on O2 consumption was studied before and after inhibition of lipolysis with β-pyridylcarbinol—a nicotinic acid derivative. During continuous is...

Effect of hematocrit variations on coronary hemodynamics and oxygen utilization.

Twenty-five closed-chest pentobarbitalized dogs were used for studying coronary flow dynamics and myocardial oxygen utilization following variations of hematocrit (Hct) by isovolumetric exchange of blood with plasma or packed red cells. Coronary blood flow (133Xe washout) and cardiac output varied inversely with Hct. Coronary systemic, and pulmonary flow resistances varied in the same direction with Hct. Blood viscosity played a significant role in determining the flow resistances in these three regions. Analysis of vascular hindrance (vascular resistance/blood viscosity) suggested that coronary vasodilation occurred following Hct changes beyond the range of 20-60%. In systemic and pulmonary circulations, however, there was vasoconstriction following hemodilution. The range of optimum Hct for maximum O2 transport (blood flow X arterial O2 content) was much wider in coronary (20-60% Hct) than in systemic circulation (40-60% Hct). The O2 consumptions in total body and in myocardium were essentially constant over a wide range of Hct (20-60%). The maintenance of total body O2 consumption over the Hct range of 20-40% was attributable to an increase in A-V O2 extraction. The O2 extraction ratio in the coronary circulation was constant over the entire range of Hct studied, suggesting that the myocardial O2 consumption was primarily determined by the coronary O2 transport.

Metabolic Gas Exchange Measurement in the Premature

Accurate measurement of total body production and O2 consumption in premature infants would make possible estimates of total caloric production to guide nutritional replacement and assess adequacy of food substrate utilization. A practical method for making these measurements in extubated, premature infants following patent ductus (PDA) ligation was developed: the infant is placed in a clear plastic bag sealed except for a gas inlet opposite the face and gas and lead/tubing exit at the foot; using a computerized mass spectrometer already in use for automated respiratory monitoring in the surgical unit, O2 and CO2 concentrations are sampled at the inlet and outlet; gas flow (0.5 - 1.0 1/min/Kg) is measured by a timed Wright spirometer or Douglas Bag collection and corrected to STPD. , , RE and caloric estimates are calculated. Daily serial measurements in a 1.15 and a 1.41 Kg. infant were made for I week after FDA ligation. , averaged 2.6 = 0.8 cc/min and caloric production 17 ± 4 ana 22 ± 5 KCAL/day, both independent of actual caloric intake (range 24-100 KCAL/day) and below predicted levels. Insulin levels were normal. These low values suggest a depressed overall metabolic rate.

Pulmonary microembolism associated with massive transfusion: II. The basic pathophysiology of its pulmonary effects.

In animals pulmonary hypertension, a decrease in total body O2 consumption and metabolic acidosis occur after transfusion of blood with an elevated screen filtration pressure (SFP) through standard blood transfusion filters. The purpose of this study was to define in detail the pulmonary abnormalities that develop following transfusion of blood with an elevated SFP through standard blood transfusion filters. Exchange transfusions of approximately twice blood volume were administered through standard commercially available blood transfusion filters (measured pore size--200 microns) to 6 animals. SFP measurements verified the presence of large numbers of aggregates in the transfusions. Although filters reduced SFP of the stored blood somewhat, numerous microaggregates passed the filters, and post-filtration SFP remained high. After transfusion average O2 consumption decreased to 77% of normal and metabolic acidosis developed. Pulmonary arterial hypertension was associated with an increase in pulmonary shunting of blood and a decrease in pulmonary diffusing capacity. The presence of extensive numbers of microemboli in the pulmonary arteriolar and capillary bed was confirmed by microscopic examination of lung tissue.

The effects of starvation, environmental temperature and injury on the rate of disposal of glucose by the rat.

1. The disposal rate of glucose, R, given by R=k(v)Q, where Q is the quantity of plasma glucose and k(v) is a rate coefficient, was determined from the disappearance of [U-(14)C]-glucose from blood after single intravenous injection. Values of R should be close to the carbohydrate oxidation rate in the states investigated. 2. Normal rats (i) experimental methodology was studied. The best (single sampling) method gave the following results. (ii) The plasma glucose concentration (C(p)) and R were temporarily increased by the stress of handling and injection. (iii) R was increased by decreasing the environmental temperature from 29 degrees C to 20 degrees C in line with previously published (Stoner & Marshall, 1971) changes in total body O(2) consumption. (iv) Starvation decreased R such that R=constantxC(p) (2). (v) The results suggested some central control of cell permeability to glucose. 3. Injured post-absorptive rats were studied in the ebb phase after three severe injuries: scalding at 20 degrees and 29 degrees C (non-lethal) and bilateral hind-limb ischaemia at 20 degrees C (85% mortality). (i) Handling and injection did not affect C(p). (ii) The rise in C(p) after injury was not closely correlated with its severity. (iii) The value of R was nearly independent of severity. (iv) Unlike in normal rats R varied little with ambient temperature (in line with O(2) consumption) or with C(p). Values of k(v) varied inversely as C(p). (v) The results were explained in terms of a centrally integrated response to injury involving the hypothalamus which over-rode the controls operating in normal rats. Hormonal factors are discussed.

Effects of 3,5,3'-D-triiodothyronine on lipid metabolism in hypothyrodism.

To study the effects of 3,5,3'-d-triiodothyronine (d-T3) on oxygen consumption and lipid metabolism, thyroid deficiency was produced by administration of I131 to weanling rats. Hypothyroidism was evidenced by decreased growth and O2 consumption, with absence of functioning thyroid tissue at necropsy. Administration of d-T3 produced a transient fall in serum cholesterol and a more protracted fall in serum fatty acids. This was associated with a decrease in liver fatty acids and an increase in liver cholesterol. Simultaneously, incorporation of radioactive carbon into liver fatty acids and cholesterol of d-T3-treated animals was greatly increased. Total-body O2 consumption and Qo2 of myocardial homogenates were increased in animals treated with d-T3. From these data it is suggested that the hypolipemic and calorigenic effects of d-T3 are interdependent and administration at this dose level increases fatty acid utilization and cholesterol synthesis by the liver.