Effect Of Cardiac Output Research Articles

Effect of cardiac output - guided hemodynamic management on acute lung injury in pediatric living donor liver transplantation.

BACKGROUNDAcute lung injury (ALI) after liver transplantation (LT) may lead to acute respiratory distress syndrome, which is associated with adverse postoperative outcomes, such as prolonged hospital stay, high morbidity, and mortality. Therefore, it is vital to maintain hemodynamic stability and optimize fluid management. However, few studies have reported cardiac output-guided (CO-G) management in pediatric LT.AIMTo investigate the effect of CO-G hemodynamic management on early postoperative ALI and hemodynamic stability during pediatric living donor LT.METHODSA total of 130 pediatric patients scheduled for elective living donor LT were enrolled as study participants and were assigned to the control group (65 cases) and CO-G group (65 cases). In the CO-G group, CO was considered the target for hemodynamic management. In the control group, hemodynamic management was based on usual perioperative care guided by central venous pressure, continuous invasive arterial pressure, urinary volume, etc. The primary outcome was early postoperative ALI. Secondary outcomes included other early postoperative pulmonary complications, readmission to the intense care unit (ICU) for pulmonary complications, ICU stay, hospital stay, and in-hospital mortality.RESULTSThe incidence of early postoperative ALI was 27.7% in the CO-G group, which was significantly lower than that in the control group (44.6%) (P < 0.05). During the surgery, the incidence of postreperfusion syndrome was lower in the CO-G group (P < 0.05). The level of intraoperative positive fluid transfusions was lower and the rate of dobutamine use before portal vein opening was higher, while the usage and dosage of epinephrine during portal vein opening and vasoactive inotropic score after portal vein opening were lower in the CO-G group (P < 0.05). Compared to the control group, serum inflammatory factors (interleukin-6 and tumor necrosis factor-α), cardiac troponin I, and N-terminal pro-brain natriuretic peptide were lower in the CO-G group after the operation (P < 0.05).CONCLUSIONCO-G hemodynamic management in pediatric living-donor LT decreases the incidence of early postoperative ALI due to hemodynamic stability through optimized fluid management and appropriate administration of vasopressors and inotropes.

The effect of cardiac output on the pharmacokinetics and pharmacodynamics of propofol during closed-loop induction of anesthesia

Background and objectiveIntraoperative hemodynamic stability is essential to safety and post-operative well-being of patients and should be optimized in closed-loop control of anesthesia. Cardiovascular changes inducing variations in pharmacokinetics may require dose modification. Rigorous investigational tools can strengthen current knowledge of the anesthesiologists and support clinical practice. We quantify the cardiovascular response of high-risk patients to closed-loop anesthesia and propose a new application of physiologically-based pharmacokinetic-pharmacodynamic (PBPK-PD) simulations to examine the effect of hemodynamic changes on the depth of hypnosis (DoH). MethodsWe evaluate clinical hemodynamic changes in response to anesthesia induction in high-risk patients from a study on closed-loop anesthesia. We develop and validate a PBPK-PD model to simulate the effect of changes in cardiac output (CO) on plasma levels and DoH. The wavelet-based anesthetic value for central nervous system monitoring index (WAVCNS) is used as clinical end-point of propofol hypnotic effect. ResultsThe median (interquartile range, IQR) changes in CO and arterial pressure (AP), 3 min after induction of anesthesia, are 22.43 (14.82-36.0) % and 26.60 (22.39-35.33) % respectively. The decrease in heart rate (HR) is less marked, i.e. 8.82 (4.94-12.68) %. The cardiovascular response is comparable or less enhanced than in manual propofol induction studies. PBPK simulations show that the marked decrease in CO coincides with high predicted plasma levels and deep levels of hypnosis, i.e. WAVCNS < 40. PD model identification is improved using the PBPK model rather than a standard three-compartment PK model. PD simulations reveal that a 30% drop in CO can cause a 30% change in WAVCNS. ConclusionsSignificant CO drops produce increased predicted plasma concentrations corresponding to deeper anesthesia, which is potentially dangerous for elderly patients. PBPK-PD model simulations allow studying and quantifying these effects to improve clinical practice.

A mathematical model of CO2, O2 and N2 exchange during venovenous extracorporeal membrane oxygenation

BackgroundVenovenous extracorporeal membrane oxygenation (vv-ECMO) is an effective treatment for severe respiratory failure. The interaction between the cardiorespiratory system and the oxygenator can be explored with mathematical models. Understanding the physiology will help the clinician optimise therapy. As others have examined O2 exchange, the main focus of this study was on CO2 exchange.MethodsA model of the cardiorespiratory system during vv-ECMO was developed, incorporating O2, CO2 and N2 exchange in both the lung and the oxygenator. We modelled lungs with shunt fractions varying from 0 to 1, covering the plausible range from normal lung to severe acute respiratory distress syndrome. The effects on PaCO2 of varying the input parameters for the cardiorespiratory system and for the oxygenator were examined.ResultsPaCO2 increased as the shunt fraction in the lung and metabolic CO2 production rose. Changes in haemoglobin and FIO2 had minimal effect on PaCO2. The effect of cardiac output on PaCO2 was variable, depending on the shunt fraction in the lung.PaCO2 decreased as extracorporeal circuit blood flow was increased, but the changes were relatively small in the range used clinically for vv-ECMO of > 2 l/min. PaCO2 decreased as gas flow to the oxygenator rose and increased with recirculation. The oxygen fraction of gas flow to the oxygenator had minimal effect on PaCO2.ConclusionsThis mathematical model of gas exchange during vv-ECMO found that the main determinants of PaCO2 during vv-ECMO were pulmonary shunt fraction, metabolic CO2 production, gas flow to the oxygenator and extracorporeal circuit recirculation.

Bioimpedance cardiography in pregnancy: A longitudinal cohort study on hemodynamic pattern and outcome.

BackgroundPregnancy associated cardiovascular pathologies have a significant impact on outcome for mother and child. Bioimpedance cardiography may provide additional outcome-relevant information early in pregnancy and may also be used as a predictive instrument for pregnancy-associated diseases.MethodsWe performed a prospective longitudinal cohort trial in an outpatient setting and included 242 pregnant women. Cardiac output and concomitant hemodynamic data were recorded from 11th–13th week of gestation every 5th week as well as at two occasions post partum employing bioimpedance cardiography.ResultsCardiac output increased during pregnancy and peaked early in the third trimester. A higher heart rate and a decreased systemic vascular resistance were accountable for the observed changes. Women who had a pregnancy-associated disease during a previous pregnancy or developed hypertension or preeclampsia had a significantly increased cardiac output early in pregnancy. Furthermore, an effect of cardiac output on birthweight was found in healthy pregnancies and could be confirmed with multiple linear regression analysis.ConclusionsCardiovascular adaptation during pregnancy is characterized by distinct pattern described herein. These may be altered in women at risk for preeclampsia or reduced birthweigth. The assessment of cardiac parameters by bioimpedance cardiography could be performed at low costs without additional risks.

Brain function monitoring during off pump cardiac surgery: the effect of cardiac output on cerebral perfusion in a patient with severe extracranial vascular disease

Zanatta, P.1; Valfrè, C.2; Bosco, E.1; Salandin, V.1; Sarpellon, M.1; Pinto, F.3 Author Information

Sevoflurane pharmacokinetics: effect of cardiac output

Sevoflurane uptake (Vsevo) can be predicted by the square root of time model or the four-compartment model. However, Vsevo and the effect of cardiac output on anaesthetic uptake have not been quantified clinically. After obtaining IRB approval and informed consent, 34 adult patients received closed-circuit anaesthesia with sevoflurane for 1 h. The end-expired sevoflurane concentration was maintained at 2.6% by infusion of liquid sevoflurane into the breathing system. In a subgroup of 12 patients, cardiac output was measured every 5 min by thermodilution (CO group). The effect of patient characteristics (age, height, weight, body surface area) and cardiac output on Vsevo were determined, and Vsevo was compared with the theoretical models. In the CO group, measured cardiac output was used in the formulae of these models. A two-exponential curve described average Vsevo well: Vsevo (ml liquid) = 0 + 1.62 x (1 - e(-2.3)xt) + 18.1 x (1 - e(-0.0089xt), r2 > 0.999. There was no correlation between Vsevo and patient characteristics, except that Vsevo was greater in patients with a greater cardiac output (r2 = 0.36) and cardiac index (r2 = 0.35). The rate of sevoflurane uptake decreased less than predicted by the square root of time and four-compartment models, even when measured cardiac output was used in the formulae. These findings confirm that the square root of time and four-compartment models do not accurately predict anaesthetic uptake. In addition, uptake of sevoflurane cannot be predicted by patient characteristics but was higher in patients with a higher cardiac output.

The effect of cardiac output on the onset of neuromuscular block by vecuronium

A relationship between cardiac output and the onset time of neuromuscular blockade administered into a peripheral vein was evaluated in 41 adult patients. Anaesthesia was induced with midazolam and fentanyl and maintained with intermittent doses of fentanyl and 66% nitrous oxide in oxygen. After immobilisation of the forearm in a splint, the ulnar nerve in the other arm was stimulated supramaximally every 10 s and the adduction force of the thumb was recorded. The times from administration of vecuronium 0.08 mg.kg-1 to first and 95% depression of twitch response was 82.4 (18.0) s and 191.7 (33.5) s (mean, SD), respectively. A significant correlation between cardiac index and the onset time of blockade was observed. This study demonstrated that the rapidity of the onset of paralysis in the adductor pollicis muscle after vecuronium injection into a peripheral vein is clearly related to cardiac output.

Validation and applications of mitral prosthetic valvular areas calculated by Doppler echocardiography

Doppler echocardiography is used in the noninvasive evaluation of mitral valve prostheses using parameters heretofore validated primarily for native valves. Accordingly, this study was designed to examine the validity and relative usefulness of valve gradient and area measurements in a group of 26 patients (17 women, 9 men, mean age 62 ± 8 years), 19 ± 4 months after implantation of different sizes (25 to 31 mm) of a given type of bioprosthesis. Areas obtained with both the continuity equation, using stroke volume measured in the left ventricular outflow tract, and the pressure halftime method are compared to known prosthetic areas derived from an in vitro hydraulic model. Areas calculated by the continuity equation correlate well with in vitro areas (r = 0.82, standard error of the y estimate = 0.1 cm 2, p <0.001), and are within the range of predicted in vitro values in 92% of cases. Areas derived by the pressure half-time method do not correlate with in vitro areas (r = 0.15, p >0.3) or continuity equation areas (r = 0.23, p >0.2), and are above the range of predicted values in 69% of cases. Correlations are also found between continuity equation areas and the peak and mean valvular gradients (r = 0.59, p <0.005 and r = -0.63, p <0.0005, respectively). Taking the effect of cardiac output on gradients into account results in projected relations between indexed prosthetic areas and the pressure gradients at rest and during exercise. These data show that the continuity equation, as applied in this study, is a valid method for assessing mitral valve bioprosthetic areas provided that there is no significant aortic or mitral regurgitation. The pressure half-time method is not valid in this situation and grossly overestimates the area in many cases. The projected relations between indexed prosthetic areas and pressure gradients may be helpful for prosthesis selection to avoid a patient-prosthesis mismatch.

Effect of Cardiac Output on Gas Exchange in One-Lung Atelectasis

To evaluate the effect of administration of dobutamine on gas exchange in patients with one-lung atelectasis during pneumonectomy, ten patients with normal pulmonary function and localized carcinoma of the lung were studied during pulmonary resection. With each patient in the lateral decubitus position, hemodynamic profiles and oxygen transport data were recorded before and after administration of dobutamine at 5 micrograms/kg/min. Patients were ventilated with one-lung anesthesia and administration of 100 percent oxygen. With infusion of dobutamine, the heart rate, cardiac index, and LVSWI significantly increased. Mean arterial pressure increased while PAP fell. Systemic and pulmonary vascular resistance also declined. Arterial oxygenization and delivery improved, while oxygen uptake was unchanged. Pulmonary shunt fraction was significantly reduced. While the mechanism for shunt reduction in our patients is unclear, operative factors may include pulmonary vasodilation with dobutamine inhibition of HPV. The negative impact of reduced HPV may have been lessened by gravitational distribution of blood flow and dobutamine-mediated reduction in PAP in our patients.

Effect of cardiac output on gravity-dependent and nondependent inequality in pulmonary blood flow

To examine the effect of cardiac output (CO) on the gravity-nondependent distribution of pulmonary blood flow, 2 X 10(6) 99mTc-labeled albumin microspheres (20 microns) were injected at end expiration into dogs (anesthetized, supine, and breathing room air spontaneously). Two animals were injected at their resting CO, two were injected during increased CO (arteriovenous fistulas induced), and two were injected at low CO (phlebotomy induced). The chest was opened and the lungs were removed, drained of blood, and dried while fully inflated. Single-photon emission-computed tomography was performed on the dry lungs to map the distribution of activity in transverse, coronal, and sagittal slices. The results confirmed the presence of a central-peripheral gravity-nondependent gradient and showed that increases in CO were associated with increases in absolute flow to both the central and peripheral regions of the lung with persistence of the central-peripheral gradient. These observations were further confirmed by direct imaging of midcoronal slices. Examination of the average flow in vertical and horizontal slices showed that, when zone 1 was not present, changes in CO affected all slices uniformly, such that when the CO doubled, the absolute flow in every slice in all three planes also doubled. We conclude that, with the exception of recruitment and derecruitment of vascular channels in the upper regions of the lung (zone 1), when CO changes, the blood flow everywhere in the lung changes uniformly and in proportion to the CO. This uniform increase in blood flow is consistent with the three-dimensional nature and resistive properties of the pulmonary vascular tree.

Interpretation of nitrate plasma concentrations. Effect of cardiac output on nitroglycerin pharmacokinetics in experimental animals

We tested the hypothesis that the pharmacokinetics of nitroglycerin might be governed by haemodynamics, viz: cardiac output. The steady state pharmacokinetics of nitroglycerin, both in arterial and in venous plasma, were investigated in 11 rats after sequential infusions either of nitroglycerin alone (10 micrograms kg-1 min-1) or of nitroglycerin plus vasopressin (the latter at 5.5 mU kg-1 min-1). Cardiac output was estimated twice in each animal using 85Sr and 141Ce microspheres. Nitroglycerin systemic clearance in arterial plasma was found to be correlated strongly with cardiac output (r = 0.784, N = 22, P less than 0.001). Using the distribution ratio of nitroglycerin between red blood cells and plasma, we determined the systemic clearance of nitroglycerin in arterial blood to be about 3/4 of cardiac output. Vasopressin co-infusion decreased both the cardiac output and the arterial nitroglycerin clearance, but it also increased the arteriovenous extraction of nitroglycerin. Thus, vasopressin had no net effect on the venous plasma clearance of nitroglycerin. In animals infused with nitroglycerin alone, cardiac output also significantly correlated with nitroglycerin venous plasma clearance (P less than 0.01) and arteriovenous extraction (P less than 0.05). These data indicate that haemodynamic alterations may have profound effects on the observed plasma concentrations of nitroglycerin. These parameters need to be standardized and controlled if meaningful plasma concentrations of organic nitrates are to be obtained and interpreted.

Effect of Cardiac Output on Color Doppler Flow Mapping Measurement for Aortic Regurgitation

Effect of Cardiac Output on Color Doppler Flow Mapping Measurement for Aortic Regurgitation

Effect of cardiac output on extravascular lung water measurements made with the thermoconductivity method.

The authors tested the effects of injectate temperature and of changing cardiac output on the measurement of lung water by the thermoconductivity technique (ETVL). Cardiac output in dogs was increased and decreased with isoproterenol and halothane, respectively. Post mortem extravascular lung water (pulmonary extravascular tissue weight [PETW] was determined using a weighing technique. Cardiac output varied between 0.7 and 8.8 l/min and did not influence the ETVL measurement. The authors conclude ETVL measured by the thermoconductivity technique is not influenced by large changes in cardiac output.

The effect of cardiac output on arterial blood oxygenation.

The effect of cardiac output on arterial blood oxygenation.

PITUITARY‐GONADAL DYSFUNCTION IN LOW‐OUTPUT CARDIAC FAILURE

Diminished cardiac output and digoxin therapy appear to have opposing effects on testosterone, oestradiol and luteinizing hormone concentrations. Depression of the levels of these hormones was significantly correlated with a decrease in cardiac index and elevation was noted by digoxin therapy of long duration. The effect of cardiac output is most marked on testosterone and that of digoxin on oestradiol.

Effect of cardiac output on pulmonary shunt.

The effect of cardiac output on pulmonary shunt was studied in living lungs of human patients and dogs which had alveoli and blood vessels, and also in artificial lung (bubble-type oxygenator) which had no such structural factors. In spite of such a structural difference, quite similar results were observed in both living and artificial lungs, and this suggests that some common factors other than the change in blood vessels result in the change in pulmonary shunt. It was observed that pulmonary shunt increased as the saturation of mixed venous blood became higher. It was clarified that the oxygen-receiving capacity of blood decreased as the oxygen saturation of mixed venous blood became higher. It was clarified that the oxygen-receiving capacity of blood decreased as the oxygen saturation became higher, i.e., the amount of reduced hemoglobin became less. The reduction in oxygen-receiving capacity of blood results in the reduction in oxygen-transfer efficiency from alveoli to blood and hence pulmonary shunt increases, and this can be regarded as a kind of shunt-like effect. It can be concluded that the change in pulmonary shunt by cardiac output is not due to the change in the lung function but is caused by the change in the oxygen-receiving capacity of the mixed venous blood.

Effect of cardiac output on the in vivo CO 2 titration curve during acute breathing of CO 2 in the dog

The slope of in vivo CO 2 titration curve ( in vivo slope, d[HC0 − 3]p/dpHp, unit: slyke) changes with the time of exposure to altered P co 2 The effects of change in cardiac output during the titration with high P co 2 on the time course of change in the in vivo slope and on the value of the slope were investigated in anesthetized dogs. The titration was carried out by means of air and 90-min periods of CO 2, breathing (12% C0 2–21% O 2 in N 2), the in vivo slope being determined at 5, 10, 30, 60 and 90 min of the CO-s breathing. In spontaneously breathing dogs there was a 60% increase in cardiac output during CO 2 breathing and the in vivo slope reached an apparent steady state no later than 10 min. The arterial blood showed a greater slope (13 slyke) than the mixed venous blood (11 slyke) in these dogs. In dogs with controlled ventilation there was no increase in cardiac output during CO 2 breathing and the apparent equilibration of the titration took 30 min. The in vivo slope was the same (8 slyke) in both of arterial and mixed venous blood. The lower slope value in the latter dogs was discussed in relation to a possible increase in the extracellular fluid volume during CO 2 breathing.