Mean Systemic Vascular Resistance Index Research Articles

Pilot study: advanced haemodynamic monitoring after acute spinal cord injury-Keep the pressure up?

BackgroundAlthough the use of vasopressors to maintain haemodynamic goals after acute spinal cord injury (SCI) is still recommended, evidence regarding the target values and possible risks of this practice is limited, and data on haemodynamic parameters unaffected by catecholamines are rare. In this pilot study, we show the haemodynamic profile of patients with acute SCI mainly unaffected by vasopressor use and other factors that influence the cardiovascular system.MethodsFrom March 2018 to March 2020, we conducted a prospective, single-centre pilot study of 30 patients with acute SCI. Factors that could affect the cardiocirculatory system other than SCI (sepsis, pre-existing heart disease or multiple trauma) led to exclusion. A total of 417 measurements were performed using the PiCCO™ system.ResultsThe mean systemic vascular resistance index (SVRI, 1447.23 ± 324.71 dyn*s*cm−5*m2), mean central venous pressure (CVP, 10.69 ± 3.16) and mean global end-diastolic volume index (GEDVI, 801.79 ± 158.95 ml/m2) deviated from the reference range, while the mean cardiac index (CI), mean stroke volume index (SVI), mean arterial pressure (MAP), and mean heart rate (HR) were within the reference range, as indicated in the literature. A mixed model analysis showed a significant negative relationship between norepinephrine treatment and MAP (83.97 vs. 73.69 mmHg, p < 0.001), SVRI (1463.40 vs. 1332.14 dyn*s*cm−5*m2, p = 0.001) and GEDVI (808.89 vs. 759.39 ml/m2, p = 0.001).ConclusionThese findings could lead to an adaptation of the target range for SVRI and MAP in patients with acute SCI and therefore reduce the use of vasopressors.

Early postoperative hemodynamic instability after heart transplantation \u2013 incidence and metabolic indicators

BackgroundPrimary graft dysfunction (PGD) is the main cause of death in the first 30 days after heart transplantation (HTX), accounting for approximately 40% of mortality. The study’s primary aim was to assess the incidence of PGD, following the International Society for Heart and Lung Transplantation consensus, and to compare it with the incidence of significant postoperative hypotension despite administration of high-dose inotropes and vasoconstrictors. The secondary aim of the study was to determine changes in biochemical markers that accompany the phenomenon.MethodsForty-five patients who underwent HTX between 2010 and 2015 were enrolled in this study, and detailed hemodynamic and metabolic data from the first 48 postoperative hours were collected and analyzed. Hemodynamic instability was defined as significant postoperative hypotension (mean arterial pressure (MAP) < 60 mmHg) combined with a high inotrope score (> 10). Data for long-term mortality were obtained from the population registration office.ResultsPGD incidence was relatively low (17.8%); however, hemodynamic instability was common (40%). Among unstable patients, MAP was insufficient for end-organ perfusion (51.4 ± 9.5 mmHg) but no decrease in left ventricular function was observed (cardiac index, 2.65 ± 0.6 l/min/m2; left ventricular ejection fraction, 52.9 ± 15.5%). Within this group, mean systemic vascular resistance index (961 ± 288 dyn*s*m2/cm5) was low despite receiving high doses of vasoactive agent (norepinephrine 0.21 (0.06-0.27) μg/kg/min during first 24 h postoperatively and 0.21 (0.01-0.27) μg/kg/min during next 24 h postoperatively). After HTX, serum lactate levels were initially significantly higher in patients with hemodynamic instability (p = 0.002); however, impaired lactate clearance was not observed (p = 0.366), and lactate levels normalized within the first 24 h postoperatively. Postoperative hemodynamic instability altered the long-term outcome and increased 5-year mortality after HTX (p = 0.034).ConclusionsHemodynamic instability is a more common phenomenon than PGD. Only early postoperative serum lactate levels correspond with hemodynamic instability following HTX. Postoperative hemodynamic instability is associated with poor long-term survival among HTX recipients.

Degree of Portal and Systemic Hemodynamic Alterations Predict Recurrent AKI and Chronic Kidney Disease in Patients With Cirrhosis.

The relevance of hemodynamic derangements on the incidence of recurrent acute kidney injury (AKI) and chronic kidney disease (CKD) in patients with cirrhosis is largely unknown. Consecutive patients with cirrhosis with a complete record of baseline hemodynamics were followed for identifying risk factors for the development of recurrent AKI and CKD by using negative binomial regression and competing risk analysis, respectively. Consecutive patients with cirrhosis (n = 2013, age 50.1 ± 11.8 years, 80% male, Child A:B:C percentage 13.7:52.9:33.4, and mean Child‐Turcotte‐Pugh score 8.6 ± 1.8) were enrolled, 893 (44.3%) of whom received beta‐blockers, with 44.2% responders. Prior AKI was noted in 12.4% at enrollment. At a median follow‐up of 379 (interquartile range: 68‐869) days, AKI developed at a rate of 0.37 episodes per person‐year, and 26% patients developed CKD. A lower mean number of AKI episodes (0.05 ± 0.25 vs. 0.42 ± 0.868; P < 0.001), CKD (subdistribution hazard ratio 0.74 [0.54‐1.02]), and mortality (hazard ratio 0.21 [0.06‐0.73]) were observed in beta‐blocker responders. Albuminuria was an independent risk factor for recurrent AKI, CKD, and mortality (P < 0.05). Lower systemic vascular resistance index predicted hemodynamic response (odds ratio 2.04 [1.29‐3.22]), cumulative AKI episodes (ratio of means 0.10 [0.08‐0.14]), and development of CKD (subdistribution hazard ratio 0.70 [0.58‐0.83]). Higher hepatic venous pressure gradient (≥17 mm Hg) predicted AKI episodes (ratio of means 1.76 [1.32‐2.35]) but not CKD. Conclusion: High portal pressure and severe vasodilatation predispose patients with cirrhosis to repeated AKI episodes and development of CKD. Response to beta‐blockers and therapies targeting the vasodilatory state could prevent frequent AKI and the risk of CKD development. Albuminuria could serve as an early marker of renal dysfunction in patients with cirrhosis.

Non-invasive estimation of cardiac index in healthy volunteers.

The primary objective was to non-invasively measure the cardiac index (CI) and associated haemodynamic parameters of healthy volunteers and their changes with age. This was a single centre, prospective, observational study of healthy volunteers aged between 20 and 59 years, using the ClearSight™ (Edwards Life Sciences, Irvine, CA, USA) device. We recorded 514 observations in 97 participants. The mean CI was 3.5 l/min/m² (95% confidence interval [95% CI] 3.4 to 3.7 l/min/m²). The mean stroke volume index (SVI) was 47 ml/m² (95% CI 45 to 49 ml/m²) and the mean systemic vascular resistance index was 2,242 dyne.s/cm⁵/m² (95% CI 2,124 to 2,365 dyne.s/cm⁵/m²). There was an inverse linear relationship between increasing age and CI (<i>P</i> <0.0001), which decreased by 0.044 l/min/m² (95% CI -0.032 to -0.056 l/min/m²) per year. This change was mostly due to a decrease in SVI of 0.45 ml/m² (95% CI 0.32 to 0.57 ml/m²) per year (<i>P</i> <0.0001). The mean CI of young healthy humans is approximately 3.5 l/min/m² and declines by approximately 40 ml/min/m² per year, mostly due to a decline in stroke volume (SV). These findings have significant implications regarding the clinical interpretation of haemodynamic parameters and the application of these results to individual patients.

The hemodynamic effects of phenoxybenzamine in neonates, infants, and children

Study Objectives To evaluate the hemodynamic effects of the long-acting, α-adrenergic blocker, phenoxybenzamine, in children of different age groups. Design Retrospective chart review. Setting Tertiary-care, congenital cardiac surgery center. Measurements The data of 75 pediatric patients who received phenoxybenzamine while undergoing surgical repair of congenital heart defects on cardiopulmonary bypass (CPB) were studied. Patients were selected in three age groups: younger than one month (n = 25), one to 12 months (n = 25), and one to 5 years (n = 25). All patients received a full dose of phenoxybenzamine 1 mg/kg. Demographics, CPB duration, mean arterial pressure on CPB, mean flow on CPB (normalized to body surface area), and central-to-peripheral temperature gradients were recorded. Systemic vascular resistance index (SVRI) was calculated. Main Results Cardiopulmonary bypass duration was significantly longer in the age group of younger than 1 mo than in the older groups. Mean CPB flow/body surface area was similar in all children (3.45 ± 0.9, 3.74 ± 0.69, and 3.48 ± 0.59 L/min/m 2, respectively; P < 0.28). However, mean SVRI was significantly lower in children younger than 1 mo (997.3 ± 233, 1196.9 ± 394, and 1168.83 ± 227 dynes/cm 2m 5; P < 0.04). Temperature gradient was significantly narrower in patients younger than one month than those who were one to 12 months and one to 5 years at the end of cooling (0.90°C ± 0.1°C, 1.04°C ± 3.61°C, 1.4°C ± 3.07°C; P < 0.001) at end-rewarming and termination of CPB (4.58°C ± 2.36°C, 6.23°C ± 4.17°C, 7.32°C ± 3.46°C; P < 0.02). Multivariate analysis showed that patient age was a significant variable affecting response to phenoxybenzamine, after adjusting for duration of CPB ( P = 0.31), mean hematocrit on CPB ( P = 0.86), and core cooling temperature ( P = 0.34). Conclusion The effect of phenoxybenzamine on SVRI, cooling, and rewarming on CPB varies with age as shown by more profound vasodilatation and narrower temperature gradients.

Nitric Oxide Production is More Prominent in off-Pump than in On-Pump Coronary Artery Bypass Surgery

The aim of our study was to elucidate the extent to which cardiopulmonary bypass contributes to endogenous nitric oxide (NO) production in patients undergoing coronary artery bypass grafts (CABG). One-hundred-and-sixteen patients undergoing elective CABG with (on-pump, n=66) and without cardiopulmonary bypass (off-pump, n=50) were included. Urinary nitrite/nitrate (NOx) excretion was measured as an index of endogenous NO production during the first two postoperative days. Haemodynamic profiles, serum CK-MB and C-reactive protein (CRP) concentrations were measured after the operation. There was no significant difference in urinary NOx/creatinine (Cr) excretion on day one post CABG. The mean urinary NOx/Cr excretion ratio significantly (P < 0.01) decreased from days one to two in the on-pump group, but not in the off-pump group. The mean urinary NOx/Cr excretion ratio was significantly (P < 0.01) higher in the off-pump group (0.51 +/- 0.26 micromol/mg) than in the on-pump group (0.38 +/- 0.20 micromol/mg) on day two. The mean serum CRP concentration was also significantly (P < 0.01) higher in the off-pump group than in the on-pump group on day two. There was no significant difference in the mean cardiac index or the mean systemic vascular resistance index between the two groups after surgery. The mean serum CK-MB concentration was significantly (P < 0.05) lower in the off-pump group than in the on-pump group on days one and two. These findings suggest that endogenous NO production is stimulated by a surgical inflammatory response and that the cardiopulmonary bypass procedure per se is not the inciting stimulus for NO production in patients undergoing CABG.

Hemodynamic and Metabolic Effects of Dobutamine in 18 Patients After Open Heart Surgery

Low cardiac output syndrome frequently follows cardiopulmonary bypass (CPB) surgery. In the present study, we used dobutamine to increase cardiac index (CI) and oxygen delivery (DO2) in 18 patients after open heart surgery. Using increasing doses of dobutamine up to 10 micrograms/kg.min-1, we observed statistically significant (p less than .01) increases in mean CI (2.50 +/- 0.10 to 3.56 +/- 0.18 L/min.m2) and in mean heart rate (HR) (83 +/- 3 to 105 +/- 3 beat/min). Mean systemic vascular resistance index decreased significantly (p less than .01) in all patients (2271 +/- 101 to 1648 +/- 83 dyne.sec/cm5.m2). Pulmonary vascular resistance index did not change in the ten coronary artery bypass graft patients, but decreased significantly (p less than .01) in the eight valve replacement patients (561 +/- 98 to 421 +/- 79 dyne.sec/cm5.m2). Mean DO2 increased in all patients, although there was no concomitant increase in oxygen consumption (VO2) in four patients. We observed a significant (p less than .01) increase in mean VO2 in the remaining 14 patients (110 +/- 6 to 148 +/- 12 ml/min.m2), in spite of significant decreases in PaO2 and increases in right-to-left intrapulmonary shunting. Although increases in HR and ventricular arrhythmias may limit its use, dobutamine increases CI and DO2 in patients after CPB. In the present study, dobutamine's varying metabolic effect exemplifies the need for close monitoring of hemodynamic and metabolic variables when using vasoactive drugs in the postoperative period.

Hemodynamic and metabolic effects of dobutamine in 18 patients after open heart surgery

Low cardiac output syndrome frequently follows cardiopulmonary bypass (CPB) surgery. In the present study, we used dobutamine to increase cardiac index (CI) and oxygen delivery (DO2) in 18 patients after open heart surgery. Using increasing doses of dobutamine up to 10 micrograms/kg.min-1, we observed statistically significant (p less than .01) increases in mean CI (2.50 +/- 0.10 to 3.56 +/- 0.18 L/min.m2) and in mean heart rate (HR) (83 +/- 3 to 105 +/- 3 beat/min). Mean systemic vascular resistance index decreased significantly (p less than .01) in all patients (2271 +/- 101 to 1648 +/- 83 dyne.sec/cm5.m2). Pulmonary vascular resistance index did not change in the ten coronary artery bypass graft patients, but decreased significantly (p less than .01) in the eight valve replacement patients (561 +/- 98 to 421 +/- 79 dyne.sec/cm5.m2). Mean DO2 increased in all patients, although there was no concomitant increase in oxygen consumption (VO2) in four patients. We observed a significant (p less than .01) increase in mean VO2 in the remaining 14 patients (110 +/- 6 to 148 +/- 12 ml/min.m2), in spite of significant decreases in PaO2 and increases in right-to-left intrapulmonary shunting. Although increases in HR and ventricular arrhythmias may limit its use, dobutamine increases CI and DO2 in patients after CPB. In the present study, dobutamine's varying metabolic effect exemplifies the need for close monitoring of hemodynamic and metabolic variables when using vasoactive drugs in the postoperative period.

Pulse oximetry during low cardiac output and hypothermia states immediately after open heart surgery

Two commercially available pulse oximeters were found to read reliably early during periods of low cardiac index (CI) and low peripheral temperature (Tp). The lowest mean CI and mean Tp values at which a reading could be obtained were 2.4 L/min.m2 and 26.5 degrees C, respectively. The highest mean systemic vascular resistance index was 2930 dyne.sec/cm5.m2. The reliability of one monitor was equally good both in a normal and low perfusion mode (i.e., when the monitor displayed a low-quality signal message). The use of locally applied vasodilating creme widened the physiologic limits within which reliable measurements could be obtained. All oximeters and sensors overestimated slightly the saturation as compared to the hemoximeter readings, possibly because of a high mean carboxyhemoglobin concentration that was found to be present.