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PubMed1996

Nisoldipine attenuates myocardial stunning induced by multiple coronary occlusions in conscious pigs and this effect is independent of changes in hemodynamics or coronary blood flow.

Recent studies suggest that calcium channel blockers attenuate reversible post-ischemic myocardial dysfunction (myocardial "stunning") in vivo. This beneficial effect, however, has been shown either in open-chest preparations, which are subject to the confounding influence of many unphysiological conditions, or in models in which treatment caused significant hemodynamic alterations. Furthermore, all of the studies have been conducted in the dog, and almost all of them have examined the effect of calcium antagonists after a single ischemic episode. The goal of the present investigation was to assess the effect of nisoldipine in a conscious pig model of repetitive ischemia, and to determine whether the drug exerts direct cardioprotection independent of hemodynamic changes. A total of 33 conscious pigs were used. Pigs underwent a sequence of 10 2-min coronary occlusions, each separated by 2 min of reperfusion, and were randomly assigned to a treated group (n = 11), in which nisoldipine was infused at a rate of 0.5 microgram/kg/min from 15 min before the first coronary occlusion till 30 min after the last reperfusion, and a control group (n = 12), which received vehicle. Results showed that there were no significant differences between the two groups with respect to ischemic bed size or hemodynamic variables throughout the experiment. Collateral blood flow to the ischemic regions was virtually nil in both groups. During the sequence of coronary occlusions, systolic thickening fraction in the ischemic region decreased similarly in the two groups. After the 10th reperfusion, however, the recovery of wall thickening was markedly enhanced in treated compared to control pigs, with the differences being statistically significant at 5, 15, and 30 min and 1, 3, 4 and 5 h. The total deficit of wall thickening after the 10th reperfusion (an integrative assessment of post-ischemic dysfunction) was 51% less in the treated compared with the control group (P < 0.001). This study demonstrates that nisoldipine markedly attenuates myocardial stunning after multiple ischemic episodes in conscious pigs, the improvement is evident immediately after the end of the ischemic episodes and is sustained throughout the recovery phase. This beneficial effect is independent of any favourable hemodynamic changes, and therefore indicates a direct cardioprotective action of nisoldipine.

Animals↗
PubMed1993

Hormonal and splanchnic hemodynamic alterations following hepatic resection.

Reported hemodynamic changes after partial hepatectomy (PH) include elevations in portal blood flow and pressure (Ppv). The etiology of these changes is unknown. We studied degree of portosystemic shunt (PSS), splanchnic artery blood flow and resistance (Qspl, Rspl) as well as prostacyclin (PGI2), glucagon, and insulin response in rats undergoing 75% hepatectomy. The results showed that following an immediate threefold rise in portal PGI2, a hemodynamically significant PSS developed at 48 hr. The PGI2 changes paralleled the increase in portal flow (Qpv), pressure (Ppv), PSS and the decrease in Rspl. Glucagon levels also rose immediately postresection, but fell to normal prior to resolution of both PSS and hyperemia. There was no significant change in insulin or glucose levels after resection. This implies a relationship between PSS and the release of a prostanoid effecting Qpv, Qspl, and Rspl, which relates to, and possibly mediates, the hemodynamic changes following liver resection. We conclude that PH is a model of acute PHT, and that the altered splanchnic hemodynamic could relate to hepatic regeneration.

Animals↗
PubMed2001

Intestinal and hemodynamic impairment following mesenteric ischemia/reperfusion.

BACKGROUND: Clinical intestinal ischemia/reperfusion (I/R) injury results in local and systemic dysfunction. A rat model of transient mesenteric occlusion has been used to study this phenomenon. However, a systematic analysis of the rat model with respect to intestinal permeability and hemodynamics has not been carried out. MATERIALS AND METHODS: In anesthetized rats, the superior mesenteric artery was occluded for 60 min, followed by reperfusion for 4 h. Intestinal impairment was evaluated via histological examination and by measuring ex vivo apparent permeability coefficients (Papp) of mannitol (0.18 kDa), inulin (5 kDa), and dextran (70 kDa). Hemodynamic effects of intestinal I/R were determined by monitoring mean arterial pressure (MAP) and heart rate (HR) via a catheter placed in the femoral artery. RESULTS: The animal model was associated with increased ex vivo Papp for mannitol and inulin. Although I/R injury was accompanied by significant histological disruption, there was no observable alteration in dextran permeability, suggesting that the loss in normal barrier function was limited to low-molecular-weight compounds. Hemodynamic measurements indicated that reperfusion induced a precipitous and sustained fall in MAP. HR values fell sharply following reperfusion but gradually increased and eventually "overshot" to values greater than baseline. CONCLUSIONS: Our findings demonstrate the selective loss of barrier function of the small bowel following intestinal I/R. Furthermore, these results also illustrate the importance of selecting appropriate permeability markers for the evaluation of intestinal damage. In light of the significant hemodynamic disruption accompanying the animal model, our investigation also points toward the need for developing therapeutic strategies that mitigate the local and systemic effects of intestinal I/R injury.

Animals↗
PubMed2001

Bayesian modeling of the hemodynamic response function in BOLD fMRI.

In functional magnetic resonance imaging (fMRI), modeling the complex link between neuronal activity and its hemodynamic response via the neurovascular coupling requires an elaborate and sensitive response model. Methods based on physiologic assumptions as well as direct, descriptive models have been proposed. The focus of this study is placed on such a direct approach that allows for a robust pixelwise determination of hemodynamic characteristics, such as time to peak or the poststimulus undershoot. A Bayesian procedure is presented that can easily be adapted to different hemodynamic properties in question and can be estimated without numerical problems known from nonlinear optimization algorithms. The usefulness of the model is demonstrated by thorough analyzes of the poststimulus undershoot in visual and acoustic stimulation paradigms. Further, we show the capability of this approach to improve analysis of fMRI data in altered hemodynamic conditions.

Auditory Perception↗
PubMed1994

Effects of atmospheric ammonia on pulmonary hemodynamics and vascular permeability in pigs: interaction with endotoxins.

The influence of atmospheric ammonia on the somatic growth, the plasma cortisol and ammonia concentrations, and cell blood counts was investigated in pigs exposed to four concentrations (0, 25, 50, and 100 ppm) for 6 days in a specifically designed air-pollutants exposure chamber. The effects of this gas on pulmonary vascular hemodynamics and permeability and on the endotoxin-induced vascular response were also assessed using an isolated perfused lung preparation. The total pulmonary blood flow resistance (Rt) was partitioned into four components: arterial (Ra), pre-(Ra') and post-(Rv') capillary and venous (Rv). The capillary filtration coefficient (Kf,c) was evaluated by using a gravimetric technique. None of the concentrations of ammonia significantly modified the plasma cortisol and ammonia concentrations or the differential leukocyte percentages and total white blood cell count, suggesting an absence of stress related to ammonia. In exposed animals, lethargy and a concentration-related depression of the somatic growth were observed. The equation of the regression line plotted relating the mean values of the changes in body weight gain recorded over the exposure period expressed as percentages of the initial body weight (y) and ammonia concentrations (x) was: y = 3.204 - 0.177x + 0.001x2 (r = 0.99; p < or = 0.013). Endotoxin infused in the perfusion liquid of lungs from unexposed animals for 180 min induced a significant 208% increase in Rt (p < 0.001) which can be ascribed to a 338 and 180% increase in Ra' and Rv', respectively. Endotoxin infusion also induced a 62% (p < or = 0.001) increase in the Kf,c. Exposure of pigs to ammonia at any concentration did not modify the baseline values of any hemodynamic or permeability parameters. However, the hemodynamic response to endotoxins in lungs from pigs exposed to 100 ppm was significantly altered. The increase in Rt, Ra', and Rv' observed in unexposed pigs was completely abolished as shown by the limited changes in Rt (+34.9%). An intermediate reaction (+131.7%) was obtained in pigs exposed to 50 ppm. This inhibiting effect of ammonia was closely correlated with gas concentration by a linear regression (r = 0.99; p < or = 0.037). The changes in the Kf,c recorded in the control group were not modified by exposure to ammonia. It was concluded that exposure of pigs to aerial ammonia concentrations from 0 to 100 ppm for 6 days has no direct effect on the pulmonary microvascular hemodynamics and permeability and induces no stress response.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants↗
PubMed1996

Relationship between serum concentrations, hemodynamic effects, and cardiovascular lesions in dogs treated with minoxidil.

The threshold hemodynamic changes associated with the cardiovascular (CV) toxicity of minoxidil (MNX) in the dog, characterized by subendocardial necrosis, right atrial hemorrhagic lesions, and coronary vascular medial hemorrhage and necrosis, have not been defined. To determine the relationship between serum concentration, hemodynamic effects [heart rate (HR) and mean arterial pressure (MAP)] and CV toxicity, groups of female Beagle dogs were treated with a continuous iv infusion of dextrose (control) or 0.05, 0.14, 0.43, 1.44, or 4.32 mg/kg/day of MNX for 3 days. Serum concentration of free MNX increased in a dose-related manner and reached steady state within 4 hr after the initiation of infusion. There was a time-dependent, apparently dose-related increase in HR at all doses. MAP was decreased at > or = 0.14 mg/kg/day in a time- and dose-related manner. The doses or steady-state serum concentrations of MNX that showed no significant hemodynamic effects and CV toxicity were approximately 0.05 mg/kg or 3.0 +/- 0.6 ng/ml and 0.14 mg/kg or 7.3 +/- 2.0 ng/ ml, respectively. CV toxicity occurred at a serum concentration of 16.6 +/- 1.9 ng/ml where HR was increased by 65 +/- 11 beats/min and MAP was decreased by 34 +/- 2 mm Hg. A serum concentration of 7.3 +/- 2 ng/ml of MNX that increased HR by 47 +/- 14 beats/min and decreased MAP by 17 +/- 8 mm Hg was not associated with CV toxicity. This study suggests that the threshold hemodynamic effects associated with the CV toxicity of MNX in the dog are a function of an increase in HR by at least 55 beats/min and a decrease in MAP by at least 30 mm Hg. In conclusion, the safety margin of drugs like MNX, where the mechanisms of toxicity are known to be related to their pharmacologic effects, should be based on the ratio of the pharmacokinetically and metabolically adjusted dose/serum concentration of the drug that evokes comparable pharmacologic effects in the animal model and humans rather than on the ratio of the nontoxic dose/serum concentration in animals to the efficacious dose in humans.

Animals↗
PubMed2003

Importance of hemodynamics management in patients with severe head injury and during hypothermia.

OBJECTIVE: To evaluate the hemodynamics in patients with traumatic brain injury (TBI) during therapeutic hypothermia. METHODS: Subjects were 25 patients with TBI (GCS; 8 or less). Mean arterial blood pressure (MAP), cerebral perfusion pressure (CPP), cardiac index (CI), systemic oxygen delivery (DO2), systemic vascular resistance index (SVRI), and pulmonary capillary wedge pressure (PCWP) were measured. Patients were retrospectively divided into 3 groups: normothermia (n = 5; NT), and survivors (n = 14; HT-S) and non-survivors (n = 6; HT-Non-S) after hypothermia. and hemodynamics were investigated for difference among groups at 24 hours from induction of normothermia or hypothermia. RESULTS: CPP target was above 70 mmHg, however, HT-Non-S could not maintain CPP above 70 mmHg. The low CPP was the result of elevated ICP, low MAP (P < .05), or both during hypothermia. In HT-Non-S, significantly high SVRI and low CI (P < .05) causing dehydration were observed during cooling. DO2 could not be maintained in HT-Non-S during hypothermia. CONCLUSIONS: These results suggest that patients run the risk of impairing hemodynamics during therapeutic hypothermia. Hemodynamic management is essential during hypothermia. If dehydration occurs during hypothermia. MAP may be reduced due to inadequate sedation, analgesia, and excess use of diuretic agents.

Blood Pressure↗
PubMed1992

Antihypertensive efficacy and effects of nitrendipine on cardiac and renal hemodynamics in mild to moderate hypertensive patients: randomized controlled trial versus hydrochlorothiazide.

In this study antihypertensive efficacy, safety, and the effects of short-term nitrendipine administration on central and renal hemodynamics were evaluated in mild to moderate hypertensives. Our final goal was to ascertain whether the reduction in blood pressure induced by nitrendipine treatment was associated with maintained renal function. After a run-in period with placebo, 26 hypertensives without cardiac or renal disease were randomly assigned to a double-blind 8-week controlled trial with nitrendipine (N) 20 mg once a day (13 pts) or hydrochlorothiazide (HCT) 25 mg once a day (13 pts). Renal hemodynamic measurements included effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) by radionuclide study using I-131 hippuran and Tc-99m, according to the methods described by Schlegel and Gates, respectively. Effective renal blood flow [ERBF = ERPF/(1-Ht)], filtration fraction (FF = GFR/ERPF), and renal vascular resistance (RVR = MBP x 80/ERBF) were also calculated. Other hemodynamic measurements included cardiac index (CI), left ventricular (LV) ejection fraction (EF), and total peripheral resistance (TPR) measured by the first-pass radionuclide angiography technique. At the end of N or HCT administration significant decreases (p less than 0.001) in SBP, DBP, and MBP vs. baseline values were observed in both hypertensive groups. In the N group a significant decrease (p less than 0.01) in TPR and RVR, and significant increases (p less than 0.05) in CI, ERPF, and ERBF were observed. In the HCT group a significant decrease (p less than 0.05) in RVR was found without significant changes in other hemodynamic parameters. No important side effects were observed with either therapy. In conclusion, nitrendipine was effective in reducting blood pressure in mild to moderate hypertensive patients and exerted favorable effects on cardiac and renal function.

Adult↗
PubMed1995

Laparoscopy without pneumoperitoneum. Effects of abdominal wall retraction versus carbon dioxide insufflation on hemodynamics and gas exchange in pigs.

Laparoscopic surgery with CO2 insufflation is associated with adverse effects on hemodynamics and gas exchange. The abdominal wall retractor (AWR) is an alternative for pneumoperitoneum. Hemodynamics and gas exchange during the use of an AWR were compared to those of CO2 pneumoperitoneum. In eight pigs subjected to 1 h of CO2 pneumoperitoneum or abdominal wall retraction, hemodynamics, gas exchange, and oxygen transport were studied in a randomized cross-over study design. The only change observed during abdominal wall retraction was mild respiratory alkalosis. In contrast, during CO2 pneumoperitoneum mean arterial blood pressure increased 13%, central filling pressures doubled, and a small increase in cardiac output was observed. Peak airway pressures increased 50%, end-tidal CO2 increased 20%, and respiratory acidosis was induced (arterial pH from 7.46 +/- 0.07 to 7.31 +/- 0.06 and pCO2 from 33 +/- 3 mmHg to 53 +/- 4 mmHg). Arterial PO2 decreased but mixed venous oxygen saturation and oxygen consumption were unaffected. In contrast with CO2 pneumoperitoneum, laparoscopy using abdominal wall retraction was not associated with adverse effects on hemodynamics or gas exchange.

Abdominal Muscles↗
PubMed1996

Acute hemodynamic effects and preload-dependent cardiovascular profile of the partial phosphodiesterase inhibitor nanterinone in patients with mild to moderate heart failure.

Nanterinone (UK-61,260) is a novel positive inotropic and balanced-type vasodilating drug, only partially based on phosphodiesterase III inhibition. Preliminary data from controlled studies suggest satisfactory long-term efficacy and safety. As its acute hemodynamic effects in humans are unknown, an oral dose of 2 mg nanterinone was studied in 14 patients with heart failure (NYHA class II-III) on chronic diuretic and angiotensin-converting enzyme (ACE) inhibitor treatment. Before the study, patients were on a 2 g salt-balanced diet, and they received their last medication 16 hours before each study day. Hemodynamic measurements were carried out before and 0.5, 1, 1.5, 2, 2.5, 3, 4, 8, 12, and 24 hours after administration of the study drug. All patients received placebo and nanterinone on 2 consecutive days. Following nanterinone, systemic vascular resistance decreased immediately from 1699 +/- 82 (mean +/- SEM) at baseline to 1368 +/- 80 at 1 hour. Changes persisted for 12 hours. Concomitantly, there was an immediate and significant fall in pulmonary wedge pressure to 38% of baseline at 1.5 hours, together with a 20% reduction in pulmonary artery pressure. Heart rate remained unchanged and arterial pressures showed only a short, significant decrease. Cardiac index rose significantly from 2.28 +/- 0.15 at baseline to a highest value of 2.65 +/- 0.14 1/min/m2 at 1 hour. Changes persisted for 3 hours. Placebo had no effect on these variables. As, in view of its potential venodilating properties, hemodynamic improvement by nanterinone may depend on pre-existing left ventricular filling pressure, patients were subsequently grouped according to baseline pulmonary wedge pressure of > 12 mmHg (H-PCWP) and < or = 12 mmHg (L-PCWP). Cardiac index improved by 26% in H-PCWP and by 17% in L-PCWP (NS). In contrast, PCWP fell more markedly in H-PWCP than in L-PCWP (40% and 23%, respectively, p < 0.05). Thus, oral nanterinone results in a significant acute hemodynamic improvement and is well tolerated. Although changes in left ventricular filling pressure are more pronounced in patients with elevated pre-existing PCWP, cardiac pump function improves equally in patients with normal or low left ventricular filling pressure at baseline.

Aged↗
PubMed1990

Effects of carvedilol on common carotid arterial flow, peripheral hemodynamics, and hemorheologic variables in hypertension.

The effects of a beta-blocker, carvedilol, on peripheral hemodynamics and hemorheologic parameters were evaluated in 11 geriatric patients with essential hypertension [3 men and 8 women aged 62-79 years (mean, 68.6 years)]. Carvedilol was given orally after breakfast at a dose of 10 or 20 mg daily for 8 weeks. Peripheral hemodynamics, the common carotid arterial flow, and hemorheologic parameters were determined twice prior to administration and after 4 and 8 weeks of carvedilol treatment. The common carotid arterial flow was determined using the pulsed Doppler method. Peripheral hemodynamics were assessed by venous occlusion plethysmography. The hemorheologic parameters assessed include erythrocyte aggregation, erythrocyte deformability, plasma viscosity, whole-blood hematocrit, and platelet function tests. Erythrocyte aggregation was measured using an Erythrocyte Aggregometer MA-1 (Myrenne, USA), taking a high shear rate of 600 s-1 and a low shear rate of 3 s-1 as the indices. Statistical comparisons of values before and after carvedilol administration were made using the paired Student's t-test. Systolic and diastolic blood pressure were decreased by carvedilol. The common carotid arterial flow was increased, and peripheral hemodynamics were improved by carvedilol. Erythrocyte aggregation (measured at both a high and a low shear rate) and plasma viscosity were decreased, erythrocyte deformability was increased, and levels of circulating platelet aggregates were also improved by carvedilol. This improvement of hemorheologic variables may contribute to prevention of the initiation and progression of thrombosis and atherosclerosis in geriatric patients with essential hypertension.

Adrenergic beta-Antagonists↗
PubMed1990

Relationship between pharmacokinetics and hemodynamic tolerance to isosorbide-5-mononitrate.

Healthy male volunteers received three different dose regimens of a controlled-release form of isosorbide-5-mononitrate (IS-5-MN; 60 mg per tablet). Dose regimen I consisted of a single daily dose of 60 mg given for 5 days. Dose regimen II was started with a dose of 60 mg, followed by 30 mg 12 h later and thereafter every 8 h. The last dose, on the 5th day was again 60 mg. In dose regimen III 60 mg followed by 30 mg 6 h later were administered every day for 5 days. The peripheral arterial and venous effects of IS-5-MN during the first and last dosing interval were followed by changes in the finger pulse curve, standing systolic blood pressure, heart rate, and venous distensibility. Plasma concentrations of IS-5-MN were measured frequently following the first and the last dose. Following dose regimen I all hemodynamic effects produced by the first dose were maintained during the study. The maximal plasma concentrations were about 400 ng/ml and the trough value, lower than 100 ng/ml. Following dose regimen II the hemodynamic effects of IS-5-MN and sublingual glyceroltrinitrate were completely abolished on the 5th day. Trough plasma concentrations were approximately 300 ng/ml during the entire study period. Following dose regimen III pronounced hemodynamic effects were seen on the 1st day. However, a significant attenuation of the hemodynamic effects was measured on the 5th day, when trough plasma concentrations were between 100 and 230 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Hemodynamic changes in acute adrenal insufficiency.

OBJECTIVE: Acute adrenocortical insufficiency is an unusual cause of isolated shock. The purpose of this study is to describe the cardiovascular changes in 6 patients with acute adrenal insufficiency presenting with hemodynamic instability. DESIGN: Retrospective and prospective study. SETTING: Medical intensive care unit in a university hospital. PATIENTS: 6 patients studied by right cardiac catheterization. MEASUREMENTS AND RESULTS: Results before glucocorticoid treatment show two possible hemodynamic states: 1) myocardial depression with hypovolemia in 3 patients, and 2) hyperdynamic shock with high cardiac output and diminished systemic arterial resistance in 3 other patients. The 3 patients presenting hyperdynamic shock were all given intravenous fluid therapy of over 20 ml/kg before the first hemodynamic measurement. For 2 other patients with low cardiac index and high systemic arterial resistance studied prospectively, 20 ml/kg intravenous fluid therapy transformed the hemodynamic state to hyperdynamic shock. The cardiovascular effect of glucocorticoid treatment studied in 4 patients was resulted in an improvement in the left ventricular systolic work index. CONCLUSIONS: Diagnosis of acute adrenocortical insufficiency must be considered if clinical manifestations are present suggesting septic shock without any obvious infectious cause in patients having undergone considerable intravenous fluid therapy as an initial course of treatment.

Acute Disease↗
PubMed1982

Variable hemodynamic response to sodium nitroprusside in hypertensive crisis.

Five patients, three males and two females, admitted with severe hypertensive crisis underwent hemodynamic investigations before and during vasodilator therapy with sodium nitroprusside. In three hypervolemic patients with congestive heart failure and/or renal insufficiency, the drug induced a rapid fall in systemic arterial pressure and a beneficial effect on cardiac performance, as shown by a shift of the ventricular function curves to the left. In two hypovolemic patients, the hemodynamic response was quite different; vasodilator therapy induced a confusing clinical picture characterized by significant fluctuations in blood pressure, a severe fall in cardiac output and clinical signs of shock in spite of normal blood pressure. Hemodynamic response to vasodilator therapy with sodium nitroprusside in hypertensive crisis appears to be directly related to the circulating blood volume. The syndrome of hypertension associated with hypovolemia needs to be recognized promptly in order to avoid inappropriate therapy; in such cases volume expansion under precise hemodynamic monitoring appears to be an effective means of stabilizing the cardiocirculatory conditions.

Acute Disease↗
PubMed1993

Morning increase in hemodynamic response to exercise in patients with angina pectoris.

The present study was conducted to determine whether or not there is diurnal variation in the hemodynamic responses to stimuli that increase myocardial oxygen demand, and the effects of such variation on electrocardiograms (ECG). Fifteen patients with angina pectoris, 17 patients with old myocardial infarction, and 8 healthy controls were examined in this study. Graded exercise stress testing was conducted in the supine position, once in the morning and once in the afternoon, using a bicycle ergometer. A standard 12-lead ECG was recorded before, immediately after, and 3, 5, and 10 min after the end of the exercise. The exercise ECG and blood pressure changes were compared among the groups and, within each group, the results after morning and afternoon exercise were compared. Hemodynamic responses, including heart rate, blood pressure, and the pressure-rate product, showed greater increases in the morning than in the afternoon in angina patients and controls, in association with greater depression of the electrocardiographic ST-segment. In contrast, patients with old myocardial infarction exhibited no difference in hemodynamic responses or the ST-pattern from morning to afternoon. The results suggest that diurnal variation of hemodynamic responses to increased oxygen demand may explain, at least partly, why myocardial ischemia of effort angina is more severe in the morning than in the afternoon.

Adult↗
PubMedDate not supplied

Hemodynamics and left ventricular function: a comparison between adult racing greyhounds and greyhounds completely untrained from birth.

Trained racing greyhounds are known to have cardiomegaly, higher mean arterial pressure and cardiac indices and lower systemic arterial resistances at rest than mongrel dogs. In order to distinguish between those hemodynamic and left ventricular functional characteristics that are inborn in the greyhound as opposed to those which are acquired through training, we studied 9 adult (mean age 22.9 +/- 4.2 [S.D.] months) trained racing greyhounds within 8 days of the cessation of training and 9 adult greyhounds raised under sedentary conditions (mean age 21.7 +/- 1.4 months). Seven healthy adult mongrel dogs served as additional controls. Right and left heart catheterizations of chloralose-anesthetized animals included hemodynamic and left ventricular functional measurements before and after volume loading with 500 ml 6% dextran in normal saline. Heart weight/body weight ratios were the same in both trained and untrained greyhounds, favoring the concept that the cardiomegaly of greyhounds is genetic and not acquired. Trained greyhounds had significantly decreased systemic vascular resistance, increased cardiac index and stroke volume, and a tendency (non significant) toward elevated systemic arterial pressure in comparison to mongrels. Life-long untrained adult greyhounds had hemodynamic measurements that did not differ from mongrels; they also had significantly higher systemic vascular resistances and lower cardiac indices than trained greyhounds. Some hemodynamic characteristics of the trained adult greyhound dog are not present in completely untrained greyhounds and are the result of either training alone or training superimposed on genetic predisposition.

Animals↗
PubMed1993

Effect of a somatostatin analogue (SMS 201-995) on hemodynamics and glucagon secretion in cirrhotic rats.

The effects of somatostatin analogue, SMS 201-995, on systemic and splanchnic hemodynamics and glucagon secretion were investigated in control and cirrhotic rats induced by thioacetamide administration. Hemodynamics were measured using the radioactive microsphere method. Immunoreactive glucagon (IRG) was determined in the portal vein and femoral artery and the splanchnic output (OP) of IRG was calculated. In control rats, SMS 201-995 induced a decrease of 5.6% in portal venous inflow and a 25.8% decrease in OP of IRG. In cirrhotic rats, SMS 201-995 produced a 14% decrease in portal pressure, a 13.6% decrease in portal venous inflow, and a 57.8% decrease in OP of IRG. In systemic hemodynamics no significant changes were noted following SMS 201-995 administration in the control or cirrhotic rats. The ratio of cirrhotic rats to the controls in the rate of decrease in portal venous inflow was similar to that in the percentage of decrease in OP of IRG. We conclude that SMS 201-995 is useful for the treatment of portal hypertension because of its effect of reducing portal pressure with mild changes in systemic hemodynamics. We suspect that the decrease in portal venous inflow by SMS 201-995 is mainly due to a reduction in the release of glucagon, a vasodilatory gastrointestinal hormone.

Animals↗
PubMed1991

Hemodynamic effects of high frequency jet ventilation during acute hypovolemia.

The hemodynamic effects of high frequency jet ventilation (HFJV) at three different rates (60, 100, 200/min) and at rate 200/min combined with jet sighs 12/min (HFJV-200 + 12S) during two degrees of hemorrhagic hypovolemia were investigated in dogs. Also, the results were compared with those of intermittent positive pressure ventilation (IPPV). Two degrees of hypovolemia were produced by bleeding dogs until mean arterial pressure was 25% or 50% lower than basic value respectively. At both periods of hypovolemia, HFJV at rate 60 or 100 were found to have better hemodynamic effects than IPPV due to their lower airway pressures. However, HFJV at rate 200 or HFJV-200 + 12S did not demonstrate the same superiority because of their higher airway pressure, the latter even represented a tendency of worse hemodynamic effect than IPPV. The best cardiovascular effect was seen during HFJV at rate 100. Our study indicated that the hemodynamic effect of HFJV better than that of IPPV during acute hypovolemia can be seen only when proper ventilatory settings are chosen. Jet sighs at 12/min added to usual HFJV are not beneficial to circulatory function. It is recommended that HFJV at a rate below 200/min without jet sighs be used in patients who need respiratory support during acute hypovolemia or shock.

Animals↗