Significant Increase In Cardiac Output Research Articles

Evaluación de la compliancia vascular pulmonar mediante prueba de esfuerzo con dobutamina en pacientes candidatos a resecciones pulmonares amplias

This prospective descriptive study evaluated the utility of dobutamine in studying pulmonary vascular compliance in patients with lung neoplasms who are high risk candidates for lung resection. Seventeen consecutive patients meeting one of the following inclusion criteria were enrolled: FEV1 < 60% of theoretical value, FVC < 65%, residual volume > 130%. postoperative predictive FEV1 < 1,000 ml or PaO2 < 70 mmHg breathing room air. A Swan-Ganz catheter was inserted in the right side 24 h before surgery. The following data were recorded: heart rate (HR), mean pulmonary artery pressure (PAP), cardiac output, pulmonary vascular resistance (PVR) and arterial blood gas readings. Measurements were taken as follows: a) with the patient at rest breathing room air; b) after infusion of dobutamine 10 micrograms/kg/min; c) 30 min after breathing room air, and d) after surgery. Eleven of the 17 patients underwent pneumonectomy (5 left sided and 6 right sided). Bi-lobectomy was performed in 3 patients, segmentectomy was performed in 1 and lobectomy in 1. One patient did not undergo surgery because PAP was over 34 mmHg at baseline and did not decrease after oxygen administration. Dobutamine administration was associated with a significant increase in cardiac output (p < 0.001) and PAP (p < 0.05), with a significant decrease in PVR (p < 0.05), indicating good pulmonary vascular reserve in our cohort. No patient suffered serious complications in the postoperative period and all were released from the hospital. There were no complications related to dobutamine perfusion. We conclude that the study of pulmonary vascular function with dobutamine in high risk candidates for extensive lung resection may be a simple method for evaluating pulmonary vascular compliance before surgery, although its possible usefulness still remains to be determined.

Clinical application of the conductance catheter technique in the adult human right ventricle

This study examines the use of conductance catheters to assess human right ventricular volume. Ten patients undergoing diagnostic cardiac catheterisation underwent right heart catheterisation with a conductance catheter and micromanometer, and a thermodilution catheter before and after fluid loading. Parallel wall conductance (Vc), and the multiplication factor relating conductance and thermodilution derived stroke volumes (å) were derived at each steady state. Pressure-volume cycles were analyzed at steady state and during fluid loading. Fluid loading resulted in a significant increase in cardiac output, and change in maximum and minimum cycle volume. There was no significant change in å (mean 0.40 S.D. 0.20) or Vc (mean 126.4 S.D. 59.6 ml) at higher cardiac outputs or ventricular volumes. Right ventricular pressure-volume cycles were formed demonstrating characteristic lack of clear isovolumic contraction and relaxation phases, and low cycle efficiencies (mean 0.62 S.D. 0.16). Serial cycles recorded during volume loading defined an end systolic pressure-volume relation more reliably than a stroke work end diastolic volume relation. Thus, a conductance derived volume signal can be obtained in the human right ventricle which can be interpreted as a continuous and instantaneous index of right ventricular volume, allowing the construction of real time pressure-volume cycles.

Protective effect of labetalol on cardiovascular consequences of brain death in the swine

Assessment of the preventive effect on cardiovascular changes following experimental brain death (BD) in the pig by pretreatment with labetalol, an alpha and beta adrenoreceptor blocking agent. Experimental study. Ten 25-35 kg domestic pigs allocated either in the control group (n = 5) or the labetalol group (n = 5). BD was achieved in anaesthetized animals by the rapid inflation of a Foley catheter inserted into the sub-dural space. In the labetalol group, the agent (total: 10 +/- 3 mg.kg-1) was administered immediately before BD and thereafter over a 20-min period, in order to maintain haemodynamic parameters at control values. The following haemodynamic data were recorded over a 3 hour period after BD: heart rate (HR), dP/dtmax, mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO) and left anterior descending coronary artery blood flow (CBF). Afterwards, a dynamic loading test with 500 mL of dextran over 20 min was performed. In the control group, BD elicited a significant increase in HR (from de 96 +/- 9 to 176 +/- 11 b.min-1), dP/dtmax (from 1,960 +/- 123 to 4,904 +/- 930 mmHg.s-1), MAP (from 88 +/- 5 to 119 +/- 11 mmHg), CO (from 2.4 +/- 0.2 to 3.6 +/- 0.7 L.min-1) and CBF (from 45 +/- 6 to 73 +/- 7 mL.min-1) respectively. Apart from a slight increase in HR and a significant increase in CBF (from 34 +/- 4 to 55 +/- 6 mL.min-1), no other modifications occurred in the labetalol group. Following volume expansion, the labetalol group animals experienced a significant increase in CO (from 2.3 +/- 0.3 to 3.7 +/- 0.2 L.min-1), dP/dtmax (from 1,400 +/- 91 to 2,100 +/- 212 mmHg.s-1) and MAP (from 55 +/- 5 to 70 +/- 5 mmHg). In the opposite, a significant decrease in dP/dtmax (from 1,645 +/- 450 to 628 +/- 152 mmHg.s-1) occurred in the control group. The protective effect of labetalol confirms the role played by the activation of the cardiac sympathetic nervous system in the cardiocirculatory changes following BD.

Haemodilution tolerance in the elderly.

The compensatory haemodynamic response to acute isovolaemic haemodilution in elderly patients is controversial. In awake patients a significant increase in cardiac output was described [1], whereas in anaesthetized patients no increase in cardiac output was observed [2]. Thirteen patients, 65 years of age or older, scheduled for intraabdominal surgery were studied. Exclusion criteria were: history of coronary artery disease or congestive heart failure. Anaesthesia was induced with midazolam (50-120 μg kg−1), fentanyl (3-10 μg kg−1) and pancuronium (0.12 mg kg−1) and maintained with midazolam (0.75 μg kg−1 min−1) and fentanyl (0.05 μg kg−1 min−1) infusions. Measured variables were: mean (pulmonary) arterial (M(P)AP), central venous (CVP) and pulmonary capillary wedge pressures (PCWP), heart rate (HR), cardiac index (CI, thermodilution), arterial and mixed venous blood gases, haemoglobin concentration and ST segment deviation in leads II and V5. The above measurements were performed at baseline, after 6 mL kg−1 and after 12 mL kg−1 haemodilution (isovolaemic exchange of blood with 6% hydroxyaethyl starch). Responses to haemodilution were analysed by means of a repeated measures Anova (P<0.05). Data are presented as means±SEM. The mean age of the patients was 73±2 years. During haemodilution haemoglobin decreased from 12.2±0.5 gm dL−1 to 9.3±0.4 gm dL−1. CVP and PCWP were stable at 5 mm Hg. CI (Fig. 1a) and oxygen (O2) extraction (Fig. 1b) increased during haemodilution resulting in a stable O2 consumption (V˙O2I) (Fig. 1c). AVDO2 decreased during haemodilution. MAP, MPAP and ST segment deviation in leads II and V5 were unchanged during haemodilution (Fig. d).Fig. 1: (abstract 2). Changes (a) in cardiac index (b) oxygen extraction (c) oxygen consumption index (d) and ST segment deviation.* sign. change (P<0.05) during haemodilution.Moderate isovolaemic haemodilution to a haemoglobin value of approximately 9 gm dL−1 was well tolerated by elderly patients anaesthetized with midazolam and fentanyl infusions. The compensatory response to maintain whole body O2 consumption consisted in an increase of both, cardiac output and O2 extraction. This is in contrast to the response pattern of elderly patients anaesthetised with a neuroleptic analgesic technique, where only an increase in O2, extraction but no increase in cardiac output was observed during haemodilution [2]. The anaesthesia technique thus might modulate the compensatory response mechanisms during haemodilution.

Correction of blood pH attenuates changes in hemodynamics and organ blood flow during permissive hypercapnia

To determine whether changes in cardiac output, regional blood flow, and intracranial pressure during permissive hypercapnia are blood pH-dependent and can be attenuated by correction of intravascular acidemia. Prospective, controlled study. Research laboratory. Female Marino ewes. Animals were instrumented with a pulmonary artery catheter, femoral arterial and venous catheters, a catheter in the third cerebral ventricle, and ultrasonic flow probes on the left carotid, superior mesenteric, and left renal arteries 1 wk before experimentation. At initiation of the protocol, ewes underwent endotracheal intubation and mechanical ventilation under general anesthesia. Minute ventilation was reduced to induce hypercapnia with a target PaCO2 of 80 torr (10.7 kPa). In the pH-uncorrected group (n = 6), arterial blood pH was allowed to decreased without treatment. In the pH-corrected group (n = 5), 14.4 mEq/kg of sodium bicarbonate was given intravenously as a bolus to correct arterial blood pH toward a target arterial pH of 7.40 (dose calculated by the Henderson-Hasselbalch equation). Arterial blood pH, PCO2, cardiac output, intracranial pressure, and carotid, superior mesenteric, and renal artery blood flow rates were measured at normocapnic baseline and at every hour during hypercapnia for 6 hrs. In the pH-uncorrected group, arterial blood pH decreased from 7.41 +/- 0.03 at normocapnia to 7.14 +/- 0.01 (p < .01 vs. normocapnia) as blood PCO2 increased to 81.2 +/- 1.8 torr (10.8 +/- 0.2 kPa). In the pH-corrected group, arterial blood pH was 7.42 +/- 0.02 at normocapnia and was maintained at 7.37 +/- 0.01 while PaCO2 was increased to 80.3 +/- 0.9 torr (10.7 +/- 0.1 kPa). Significant increases in cardiac output occurred with the initiation of hypercapnia for both groups (pH-uncorrected group: 4.3 +/- 0.6 L/min at normocapnia vs. 6.8 +/- 1.0 L/min at 1 hr [p < .05]; pH-corrected group: 4.1 +/- 0.4 at normocapnia vs. 5.7 +/- 0.4 L/min at 1 hr [p < .05]). However, this increase was sustained only in the uncorrected group. Changes in carotid and mesenteric artery blood flow rates, as a percent of baseline values, showed sustained significant increases in the pH-uncorrected groups (p < .05) and only transient (carotid at 1 hr) or no (superior mesenteric) significant change in the pH-corrected groups. Conversely, significant increases in renal artery blood flow were seen only in the pH-uncorrected group during the last 2 hrs of the experiment (p < .05). Organ blood flow, as a percent of cardiac output, did not change significantly in either group. Intracranial pressure increased significantly in the pH-uncorrected group (9.0 +/- 1.5 mm Hg at normocapnia vs. 26.8 +/- 5.1 at 1 hr, p < .05), and remained increased, while showing no significant change in the pH-corrected group (8.5 +/- 1.6 mm Hg at normocapnia to 7.7 +/- 4.2 at 1 hr). Acute hypercapnia, induced within 1 hr, is associated with significant increases in cardiac output, organ blood flow, and intracranial pressure. These changes can be significantly attenuated by correction of blood pH with the administration of sodium bicarbonate, without adverse effects on hemodynamics.

Experimental Study of Extraaortic Balloon Counterpulsation as a Bridge to Other Mechanical Assists

A special extraaortic balloon was developed that can be placed around the ascending aorta. This balloon can easily support the heart temporarily in a median sternotomy field, especially in cases in which it is difficult to use intraaortic balloon pumping because of peripheral arterial disease. The goal of this study was to judge the applicability of this extraaortic balloon counterpulsation. An extraaortic balloon was placed around the ascending aorta of eight adult canines. Two heart failure models were used in this study: group A-moderate heart failure; group B-severe heart failure. In group A, the aortic systolic pressure was significantly reduced (9.3%, p < 0.01), but in group B, there was no significant change. In group A, there was a significant increase in cardiac output (12.0%, p < 0.01), but in group B, there was no significant change. The endocardial viability ratio in both groups significantly increased (group A: 11.3%, p < 0.01; group B: 11.9%, p < 0.05). An extraaortic balloon around the ascending aorta is easily applicable through a median sternotomy, and can be used as a bridge to more powerful mechanical assists when intraaortic balloon pumping cannot be used.

Hemodynamic Changes After Retroperitoneal CO2 Insufflation for Posterior Retroperitoneoscopic Adrenalectomy

Intraoperative complications and hemodynamic alterations during posterior capnoretroperitoneoscopic adrenalectomy in the prone position were investigated in 16 consecutive patients using invasive hemodynamic monitoring. Under general anesthesia with propofol and fentanyl, hemodynamic changes were made before (M1) and during retroperitoneal CO2 insufflation (15 mm Hg) [M2]; 20 mm Hg [M3]. Retroperitoneal insufflation resulted in a significant increase of cardiac output (+72%), stroke volume (+42%), mean arterial pressure (+39 %), and mean pulmonary arterial pressure (+36%). Although retroperitoneal inflation was accompanied by a significant increase of central venous pressure (+37%), an increase of preload may have lead to higher filling pressures. Heart rate, systemic vascular resistance, and pulmonary vascular resistance did not show significant changes. One pneumothorax and two cutaneous emphysemas occurred. We have demonstrated, in a small number of patients, that retroperitoneal CO2 insufflation for posterior capnoretroperitoneoscopic adrenalectomy in the prone position results in hemodynamic changes without apparent adverse effects.

Cardiac flow after fetal blood sampling in normally grown and growth‐retarded fetuses

The objective of this study was to evaluate the effect of fetal blood sampling on cardiac flow velocity waveforms. Flow velocity waveforms were measured from the ascending aorta and pulmonary artery immediately before and after fetal blood sampling in 29 normally grown and 12 growth-retarded fetuses. The latter group was characterized by abnormal Doppler indices in the umbilical artery and middle cerebral artery suggestive of uteroplacental insufficiency as the causative factor of the impaired growth. The flow velocity parameters studied were the peak velocity, the time to peak velocity, and the left and right cardiac output and their ratio. In normally grown fetuses, the peak velocity and right and left cardiac output values increased significantly after fetal blood sampling, while no significant changes were observed in the other indices considered. The gestational age at the time of the procedure was positively related to the amplitude of these changes. In growth-retarded fetuses, fetal blood sampling did not induce any significant increase in cardiac output or peak velocities, while in more than 50 per cent of the fetuses these Doppler indices decreased. The amplitude of the decrease was significantly related to the severity of acidosis in the umbilical vein. In conclusion, the cardiac haemodynamic response to fetal blood sampling differs between normally grown and growth-retarded fetuses. This difference may explain the higher rate of complications occurring in the latter group of fetuses after blood sampling.

Hemorheological and Hemodynamic Analysis of Hypervolemic Hemodilution Therapy for Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage

Hypervolemic hemodilution therapy is effective for treating neurological deficits due to cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). We monitored various hemorheological and hemodynamic parameters to assess the effects of hypervolemic hemodilution therapy in SAH patients with cerebral vasospasm. Ninety-eight patients who underwent early craniotomy for aneurysm clipping surgery after SAH were studied. Fifty-one patients (52.0%) developed symptomatic vasospasm. The hematocrit level and red blood cell aggregability were measured daily from day 1 to day 14, whereas the circulating blood volume and cerebral blood flow were measured periodically. Cardiac output and pulmonary capillary wedge pressure were also measured using a Swan-Ganz catheter. The hematocrit level was decreased significantly to 29% to 32% by hypervolemic hemodilution therapy. Red blood cell aggregability increased until day 6 but was significantly reduced by therapy. Hypovolemia tended to develop after SAH. However, patients receiving hypervolemic hemodilution therapy became normovolemic to hypervolemic, with a significant increase of cardiac output and pulmonary capillary wedge pressure. At the onset of vasospasm, cerebral blood flow was significantly lower on the operated side than on the contralateral side, and it increased on both sides with therapy. Patients with SAH develop hypovolemia, hemodynamic depression, and increased red blood cell aggregability. Hypervolemic hemodilution therapy decreases hematocrit level and red cell aggregability while increasing cardiac output. Improvement of hemorheological and hemodynamic parameters by this therapy can reverse neurological deterioration due to cerebral vasospasm.

Left-ventricular unloading by transvalvular axial flow pumping in experimental cardiogenic shock and during regional myocardial ischemia: Cardiology 1994; 84/3 (202–210)

The efficacy of the transfemoral left-ventricular assist device Hemopump (HP; 21 Fr outer diameter) was examined in experiments with adult sheep in two different models of cardiogenic shock (tachycardia shock; ischemia shock), and during ventricular fibrillation. During tachycardia (high frequency pacing-induced; n = 14), HP assist led to a significant increase in cardiac output (from 2.2 to 2.8 liters/min), mean aortic pressure (from 47.6 to 65.6 mmHg), and myocardial perfusion pressure (from 25.5 to 59.0 mmHg). Simultaneously, a normalization of body oxygen-uptake (from 1.4 to 2.5 ml/min.kg), a decrease in myocardial oxygen consumption (from 6.1 to 4.8 ml/min.100 g), and a normalization of myocardial lactate metabolism were observed during HP assist. During regional myocardial ischemia (PTCA balloon occlusion of the proximal LAD (3.5 min; n = 12), HP assist led to significant decrease in LV end-diastolic pressure (from 21.1 to 12.1 mmHg), and increase in diastolic aortic pressure (from 58 to 67 mmHg) resulting in significant increase in coronary perfusion pressure. In the early reperfusion period, myocardial release of both lactate and potassium was significantly lowered with HP assist. During ventricular fibrillation (induced by electrical stimulation; n = 9), HP flow rates decreased from 2.5 (after 10 min) to 2.1 liters/min (after 30 min). Mean aortic pressures simultaneously decreased from 64.0 to 54.6 mmHg. Perfusion conditions were sufficient for maintenance of aerobic myocardial metabolism, but were borderline for peripheral circulation. Our hemodynamic and metabolic data demonstrate beneficial effects of cardiac assist with the Hemopump 21 Fr in both tachycardia-induced severe cardiogenic shock and during acute regional myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of the plasma contact system and hemodynamic changes after graft revascularization in liver transplantation.

In this study, the relation between activation of the plasma contact system and hemodynamic changes during orthotopic liver transplantation was evaluated. Nineteen consecutive courses of OLT in 17 adult patients were investigated. Veno-venous bypass was used in all patients. Blood samples were drawn through all phases of the procedure, and analyzed for the following parameters using functional techniques (chromogenic peptide substrate assays): plasma kallikrein (KK), prekallikrein, functional plasma kallikrein inhibition, C1 inhibitor, and alpha 2-macroglobulin. Plasma high molecular weight kininogen (HK) degradation was evaluated using the immunoblotting technique. An abrupt rise in KK activities occurred within 1 min after portal reperfusion of the liver graft (7-16 U/L, P < 0.05). Simultaneously, proteolytic breakdown of HK was seen. The elevated KK activities were maintained the next 1 1/2 hr. Ten min after graft reperfusion, a significant increase in cardiac output compared with the anhepatic phase (7.2-12.4 L/min, P < 0.05) was found. At the same time, systemic vascular resistance fell significantly (817-408 dynes x sec/cm-5, P < 0.05). The increase in plasma KK activities accompanied by simultaneous degradation of HK seen immediately after reperfusion of the liver graft may be due to contact activation as recipient blood contacts with the underlying basement membrane of injured sinusoidal endothelium in the transplanted liver. We suggest that hemodynamic changes associated with the postreperfusion syndrome seen after revascularization of the liver in OLT could at least be caused in part by bradykinin release due to contact activation.

Acute hemodynamic effects of combined inhibition of neutral endopeptidase and angiotensin converting enzyme in spontaneously hypertensive rats.

Neutral endopeptidase inhibitors (NEPI) potentiate the hypotensive effect of converting enzyme inhibitors (CEI) in conscious spontaneously hypertensive rats (SHR) but the mechanism of this potentiation remains unknown. The present study assesses the hemodynamic effects of a CEI (enalaprilat 1 mg/kg; n = 9), a NEPI (retrothiorphan 25 mg/kg + 25 mg/kg/h; n = 9) and the combination (CEI+NEPI; n = 9) versus a control group (n = 9) in anesthetized spontaneously hypertensive rats. CEI alone induced a significant hypotensive effect due to a decrease (-35.1%) in total peripheral resistance (TPR), with no significant increase in cardiac output (CO). NEPI alone had a slight hypotensive effect due to a small decrease in CO. CEI+NEPI decreased the mean arterial pressure to the same extent (-26.7%) as the CEI-induced hypotensive effect, decreased TPR (-44.4%) and induced an increase in CO (+38.2%) with an increase in heart rate. In summary, NEPI combined with CEI induces large decreases in blood pressure and in TPR which do not significantly differ from the CEI-induced effects. It also induces increases in heart rate and in cardiac output in anesthetized SHR.

Direct Evidence That Perhexiline Modifies Myocardial Substrate Utilization from Fatty Acids to Lactate

Perhexiline maleate, originally classified as a calcium antagonist, is in use as an antianginal agent. The mechanism of its protective effect is unknown, but there is speculation that it involves a modification of myocardial substrate utilization, in which glycolytic sources are used rather than fatty acids. This hypothesis was tested by employing [13C]NMR isotopomer analysis to measure substrate selection in the working rat heart. Substrate utilization was measured from a mixture of substrates present at their physiological concentration, as follows: acetoacetate, glucose, lactate and long-chain fatty acids. Control perfusions were compared with those perfused with perhexiline. It was found that perhexiline increased lactate utilization, which reduced the extent of fatty acid and endogenous substrate oxidation. There was also a significant increase in cardiac output for a small and insignificant increase in oxygen consumption, which suggested an improvement in myocardial efficiency. Thus, it was confirmed by direct measurement that this drug does modify substrate oxidation, which suggests that further investigations of the role that this agent can play in the management of ischemic heart disease would be beneficial.

N-acetylcysteine Preserves Oxygen Consumption and Gastric Mucosal pH during Hyperoxic Ventilation

Hyperoxic ventilation, used to prevent hypoxemia during potential periods of hypoventilation, has been reported to paradoxically decrease whole body oxygen consumption (VO2). Reduction in nutritive blood flow due to oxygen radical production is one possible mechanism. We investigated whether pretreatment with the sulfhydryl group donor and O2 radical scavenger N-acetylcysteine (NAC) would preserve whole body VO2 and prevent deterioration of oxygenation in gastric mucosal tissue during hyperoxia. Thirty-eight patients, requiring hemodynamic monitoring (radial and pulmonary artery catheters) due to sepsis syndrome, were included in this randomized experiment. All patients exhibited stable clinical conditions (hemodynamics, body temperature, hemoglobin, FIO2 < 0.5). A gastric tonometer was placed to measure the gastric intramucosal pH (pHi), which indirectly assesses nutritive blood flow to the mucosa. Cardiac output was determined by thermodilution and VO2 by cardiovascular Fick. After baseline measurements, patients randomly received either 150 mg.kg-1 NAC (n = 19) or placebo (n = 19) in 250 ml 5% dextrose intravenously over a period of 15 min. Measurements were repeated 30 min after starting NAC or placebo infusion, 30 min after starting hyperoxia (FIO2 = 1.0), and 60 min after resetting the original FIO2. There were no significant differences between groups in any of the measurements before treatment and after the return to baseline FIO2 at the end of the study. NAC, but not placebo infusion, caused a slight but significant increase in cardiac output and decrease in systemic vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

N-acetylcysteine preserves oxygen consumption and gastric mucosal pH during hyperoxic ventilation.

Hyperoxic ventilation, used to prevent hypoxemia during potential periods of hypoventilation, has been reported to paradoxically decrease whole body oxygen consumption (VO2). Reduction in nutritive blood flow due to oxygen radical production is one possible mechanism. We investigated whether pretreatment with the sulfhydryl group donor and O2 radical scavenger N-acetylcysteine (NAC) would preserve whole body VO2 and prevent deterioration of oxygenation in gastric mucosal tissue during hyperoxia. Thirty-eight patients, requiring hemodynamic monitoring (radial and pulmonary artery catheters) due to sepsis syndrome, were included in this randomized experiment. All patients exhibited stable clinical conditions (hemodynamics, body temperature, hemoglobin, FIO2 < 0.5). A gastric tonometer was placed to measure the gastric intramucosal pH (pHi), which indirectly assesses nutritive blood flow to the mucosa. Cardiac output was determined by thermodilution and VO2 by cardiovascular Fick. After baseline measurements, patients randomly received either 150 mg.kg-1 NAC (n = 19) or placebo (n = 19) in 250 ml 5% dextrose intravenously over a period of 15 min. Measurements were repeated 30 min after starting NAC or placebo infusion, 30 min after starting hyperoxia (FIO2 = 1.0), and 60 min after resetting the original FIO2. There were no significant differences between groups in any of the measurements before treatment and after the return to baseline FIO2 at the end of the study. NAC, but not placebo infusion, caused a slight but significant increase in cardiac output and decrease in systemic vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular effects of 7.2% hypertonic saline solution in halothane anaesthetized ponies

SUMMARY The haemodynamic effects of intravenously (iv) administered hypertonic saline solution (7.2%, 4 ml/kg of body weight [bwt]) were investigated in normovolaemic ponies during halothane anaesthesia (dorsal recumbent position, intermittent pressure ventilation). Heart rate, arterial blood and pulmonary artery pressures, cardiac output, and arterial blood gases were measured throughout the experiment while related haemodynamic parameters (cardiac index, systemic and pulmonary vascular resistance, stroke volume, ventricular work) were calculated. A transient decrease in arterial blood pressure occurred during the administration of the hypertonic solution. Significant increases in cardiac output and index, stroke work, and systolic arterial pressure were observed 5 min after the administration of the hypertonic infusion. A gradual normalization of the increased parameters occurred afterwards. Heart rate and arterial blood gases remained constant throughout the study. No clinical side-effects, except for an increase in urinary production in the recovery period, were seen during and after anaesthesia.

Regional blood flow distribution in endotoxin-treated dogs: Modification by ibuprofen

Purpose: The aim of this study was to determine whether the improved hemodynamic profiles reported with cyclooxygenase inhibition during sepsis include improvements in tissue perfusion is unknown. Our hypothesis was that cyclooxygenase inhibition with ibuprofen will prevent the endotoxin-induced alterations in regional blood flow distribution from developing and/or restore the endotoxin-induced loss of responsiveness to intravascular volume expansion. Methods: We measured cardiac output, regional blood flow, and total systemic shunt flow in dogs using radiolabeled 15-μm microspheres. These parameters were assessed in control (N = 10) and endotoxin-treated animals (N = 7). Additional endotoxin-treated animals (N = 7) were also pretreated with ibuprofen. Results: Compared with controls, endotoxin-treated animals exhibited marked reductions in blood flow to most systemic organs that were not reversed with large, intravenous saline infusions lie, isotonic saline; 40 mL/kg; N = 4). By contrast, although ibuprofen pretreatment (12.5 mg/kg; N = 7) completely prevented the reductions in mean arterial pressure caused by endotoxin from occurring, it did little to prevent the development of endotoxin-induced alterations in regional blood flow distribution. Nonetheless, in contrast to the endotoxin-treated animals, there were significant increases in cardiac output and blood flow to several organs after saline infusion in the ibuprofen-pretreated animals. Conclusions: Cyclooxygenase inhibition with ibuprofen has few direct effects on regional blood flow distribution after endotoxin. However, cyclooxygenase inhibition with ibuprofen does attenuate the endotoxin-induced decrease in vascular responsiveness to intravenous saline infusion.

Favorable Effects of Total Paracentesis on Splanchnic Hemodynamics in Cirrhotic Patients With Tense Ascites

ABSTRACT Total paracentesis is widely used in the treatment of patients with cirrhosis and tense ascites. However, very little information is available regarding its consequences on splanchnic circulation, and its effects on portocollateral blood flow have not been investigated. Ten cirrhotic patients admitted because of tense ascites had measurements of hepatic and systemic hemodynamics, renal function and endogenous vasoactive neurohumoral systems at baseline, just after total paracentesis and 1 hr later. Total paracentesis caused a significant increase in cardiac output (+11%; 95% confidence interval, +4% to +19%) and a rapid fall in portal pressure, as shown by significant decreases in both the wedged hepatic venous pressure (-27% ± 8%; p&lt;0.005) and the hepatic venous pressure gradient (-10%; 95% confidence interval, -3% to -18%). This was accompanied by a marked decrease in azygos blood flow (-28%; 95% confidence interval, -13% to -43%). These favorable hemodynamic effects were associated with a fall of the elevated levels of plasma renin activity (-47% ± 9%; p&lt;0.05), plasma aldosterone (-31% ± 21%; p&lt;0.05) and plasma norepinephrine and by a decrease in levels of serum creatinine (-24% ± 15%; p&lt;0.05) and blood urea nitrogen (-4% ± 3%; p&lt;0.05). These changes were maintained 1 hr later. This study indicates that in patients with cirrhosis and tense ascites total paracentesis favorably influences the systemic hemodynamics, portocollateral blood flow and portal pressure. (Hepatology 1994;20:30–33.)

Favorable effects of total paracentesis on splanchnic hemodynamics in cirrhotic patients with tense ascites.

Total paracentesis is widely used in the treatment of patients with cirrhosis and tense ascites. However, very little information is available regarding its consequences on splanchnic circulation, and its effects on portocollateral blood flow have not been investigated. Ten cirrhotic patients admitted because of tense ascites had measurements of hepatic and systemic hemodynamics, renal function and endogenous vasoactive neurohumoral systems at baseline, just after total paracentesis and 1 hr later. Total paracentesis caused a significant increase in cardiac output (+11%; 95% confidence interval, +4% to +19%) and a rapid fall in portal pressure, as shown by significant decreases in both the wedged hepatic venous pressure (-27% +/- 8%; p < 0.005) and the hepatic venous pressure gradient (-10%; 95% confidence interval, -3% to -18%). This was accompanied by a marked decrease in azygos blood flow (-28%; 95% confidence interval, -13% to -43%). These favorable hemodynamic effects were associated with a fall of the elevated levels of plasma renin activity (-47% +/- 9%; p < 0.05), plasma aldosterone (-31% +/- 21%; p < 0.05) and plasma norepinephrine and by a decrease in levels of serum creatinine (-24% +/- 15%; p < 0.05) and blood urea nitrogen (-4% +/- 3%; p < 0.05). These changes were maintained 1 hr later. This study indicates that in patients with cirrhosis and tense ascites total paracentesis favorably influences the systemic hemodynamics, portocollateral blood flow and portal pressure.

EXERCISE IN THE TERRESTRIAL CHRISTMAS ISLAND RED CRAB GECARCOIDEA NATALIS - ENERGETICS OF LOCOMOTION

The respiratory and circulatory physiology of exercising Christmas Island red crabs Gecarcoidea natalis were investigated with respect to their annual breeding migration. Red crabs were allowed to walk for up to 45 min. During this exercise period, the functioning of the circulatory system in gas transport and the energy status of the red crabs were quantified. Energy production during exercise required both aerobic and anaerobic contributions. The aerobic scope of G. natalis was low, with only a doubling of the resting rate of oxygen consumption (resting M(dot)O2=95&plusmn;15 &micro;mol kg-1 min-1). Maximal O2 consumption was attained within the first 5 min of exercise and the level remained stable thereafter. The anaerobic contribution to energy production was directly related to the speed of locomotion. l-lactate levels in blood and leg muscle were similar throughout the exercise period; blood lactate concentration was 33.39&plusmn;2.29 mmol l-1 after 45 min of exercise. Heart rate in resting animals was 56&plusmn;7 beats min-1. At the onset of exercise, heart rate also doubled, but without a significant increase in cardiac output. Increased O2 delivery was facilitated by increased extraction from the blood. During the 45 min of exercise, glucose levels increased rapidly in the muscle tissue (from 2.30&plusmn;0.54 to 8.78&plusmn;1.20 mmol l-1) and subsequently in the blood (from 1.22&plusmn;0.26 to 2.12&plusmn;0.17 mmol l-1), fuelling increased glycolysis during locomotion. The energy production from stored glucose/glycogen was sufficient to support the energetic needs of locomotion, since the energy charge remained stable at 0.82. Haemolymph l-lactate levels in crabs sampled in the field after migration were high compared with levels in many crustacean species but equivalent to l-lactate levels in laboratory animals exercised for less than 10 min. During their migration, therefore, the red crabs avoid exceptional l-lactate build-up in the blood by either walking very slowly or intermittently. However, G. natalis are exceptionally well adapted to cope with exhaustive locomotion and the resultant severe metabolic acidosis.