Vasoactive Drugs and Hemodynamic Monitoring in Pediatric Cardiac Intensive Care: An Italian Survey

Estimation of the inferior caval vein saturation using high-fidelity non-invasive haemodynamic values and validation of modelled estimates

OBJECTIVES

Monitoring venous saturation allows identification of inadequate systemic oxygen delivery. The aim was to develop a model using non-invasive haemodynamic variables to estimate the inferior caval vein saturation and to determine its prognostic utility.

METHODS

This is a single-centre, retrospective study. A Bayesian Pearson's correlation was conducted to model the inferior caval vein saturation. Next, a Bayesian linear regression was conducted for data from all the patients and from only those with parallel circulation. Venous saturation estimations were developed. The correlation of these estimates to the actual inferior caval vein saturation was assessed. The resulting models were then applied to two validation cohorts: biventricular circulation (arterial switch operation) and parallel circulation (Norwood operation).

RESULTS

One hundred and thirteen datasets were collected across 15 patients. Of which, 65% had parallel circulation. In all patients, the measured and estimated inferior caval vein saturations had a moderate and significant correlation with a coefficient of 0.64. In patients with parallel circulation, the measured and estimated inferior caval vein saturation had a moderate and significant correlation with a coefficient of 0.61. In the biventricular circulation cohort, the estimated inferior caval vein saturation had an area under the curve of 0.71 with an optimal cut-off of 49. In the parallel circulation cohort, the estimated interior caval vein saturation had an area under the curve of 0.83 with an optimal cut-off of 24%.

CONCLUSION

The inferior caval vein saturation can be estimated utilising non-invasive haemodynamic data. This estimate has correlation with measured inferior caval vein saturations and offers prognostic utility.

The choice of perioperative inotropic support impacts the outcome of small infants undergoing complex cardiac surgery: an observational study

BACKGROUND

Vaso-inotropic agents are frequently used to prevent and/or treat low cardiac output syndrome in infants undergoing surgery for congenital heart disease. Due to the lack of comparative studies, their use is largely dependent on physician- and center preferences. The aim was to assess the impact of two different inotropic regimens, milrinone-epinephrine versus dobutamine on postoperative morbi-mortality in young children undergoing complex cardiac surgery.

METHODS

All consecutive children younger than one year of age admitted for complex cardiac surgery (Risk Adjustment in Congenital Heart Surgery-1 [RACHS-1] score ≥3) with cardiopulmonary bypass (CPB) from January 2008 to December 2018 were included. Children received either milrinone in association with low dose epinephrine (milrinone-epinephrine group) or dobutamine (dobutamine group) groups were matched and compared using a propensity score. Our primary outcome was a composite measure including either hospital death and/or the presence of at least two of the following events: respiratory failure, prolonged inotropic support, or renal failure.

RESULTS

Two hundred and fifty patients were included in the analysis. Children in the milrinone-epinephrine group (N.=184) suffered more frequently from a cyanotic heart disease and had longer surgery, CPB, and aortic cross clamp times than those in the dobutamine group (N.=66). After matching, children in the milrinone-epinephrine group had a higher incidence of severe postoperative morbidity or mortality compared to those in the dobutamine group (27.4 versus 13.9%; P=0.016). Respiratory failure (28% vs. 12%), prolonged inotropic support (71% vs. 35%) and in-hospital death (3 vs. 0%) were more frequent in the milrinone-epinephrine group.

CONCLUSIONS

In young infants undergoing complex cardiac surgery, milrinone combined with epinephrine is associated with a higher incidence of postoperative morbidity or mortality compared to dobutamine for perioperative inotropic support. Further prospective randomized studies are required to confirm this finding.

An infant with suspected missed diagnosis of Williams syndrome failed weaning off CPB after surgical correction of pulmonary stenosis: a case report and literature review

Williams syndrome (WS) is a rare congenital developmental disorder caused by the deletion of between 26 and 28 genes on chromosome 7q11.23. For patients with WS, in view of the particularity of the supravalvular aortic stenosis, choosing appropriate arterial cannula, maintaining higher perfusion pressure as well as strengthening myocardial protection during cardiopulmonary bypass (CPB) is essential to the clinical outcome. Here, we report a child with pulmonary artery valvular stenosis who failed to wean off CPB because of malignant arrhythmias and cardiac insufficiency after surgical correction of pulmonary valvular stenosis. With the assistance of extracorporeal membrane oxygenation (ECMO), emergency cardiac catheterization revealed supravalvular aortic stenosis (SVAS), which suggests a suspected missed diagnosis of WS. Finally, under the support of ECMO, the cardiac function gradually returned to normal, and the child was discharged 23 days after surgery.

An email-based survey of practice regarding hemodynamic monitoring and management in children with septic shock in China

BACKGROUND

Understanding current hemodynamic monitoring (HM) practice patterns is essential to determine education and training strategies in China. The survey was to describe the practice of HM and management in children with septic shock in China.

METHODS

We conducted an Email-based survey of members of sub-association of pediatric intensive care physicians. The questionnaire consisted of 22 questions and gathered the following information: (I) general information on the hospitals, respective ICUs and participants, (II) the availability of technical equipment and parameters of HM and (III) management simulation of septic shock in three clinical case vignettes.

RESULTS

Surveys were received from 68 institutions (87.2%) and 368 questionnaires (response-rate 45.1%) were included. Basic HM (93-100%) were reported as the most utilized parameters, followed by advanced HM which included central venous pressure (CVP) (56.0%), cardiac output (53.5%), and central venous oxygen saturation (36.7%), 61.1% (225/368) of respondents stated the utilization of non-invasive HM equipment. The factors such as ICU specialist training center (P=0.003) and more than 30 cases of septic shock per year (P=0.002) were related to the utilization of non-invasive monitoring equipment. In the simulated case vignette, 49.7% (183/368) of respondents reported performing fluid responsiveness and volume status (FR-VS) assessment. Despite differences in training centers (P=0.005) and educational backgrounds (P=0.030), FR-VS assessment was not related to the volume expansion decision.

CONCLUSIONS

There is a large variability in use advanced HM parameters, an increasing awareness and acceptance of non-invasive HM devices and a potential need for hemodynamic education and training in pediatric intensive care medicine in China.

Effects of levosimendan on ventriculo-arterial coupling and cardiac efficiency in paediatric patients with single-ventricle physiology after surgical palliation: retrospective study

OBJECTIVES

The use of levosimendan for paediatric patients with low cardiac output after congenital heart surgery has been recently described. We sought to evaluate ventriculo-arterial coupling (VAC) and other ventricular energetic parameters before and after 72 h from levosimendan start in infants with single-ventricle physiology and cardiac failure after palliation with Norwood or hybrid procedures.

METHODS

In this single-centre retrospective study, 9 consecutive patients affected by hypoplastic left heart syndrome-like anatomy were retrospectively analysed. Systolic elastance, diastolic elastance, arterial elastance, VAC and cardiac mechanical efficiency were calculated by measuring, through 2-dimensional echocardiography, end-systolic volume and end-diastolic volume and by recording mean arterial pressure and central venous pressure.

RESULTS

The median (range) weight and age were 2.8 (2.3–6) kg and 16.5 (6–116) days, respectively. After 72 h from levosimendan start, end-systolic volume significantly decreased (−1 ml, −3.2 to −0.1, P = 0.007), whereas mean arterial pressure and end-diastolic volume remained stable. Heart rate showed a significant decrease (−28 beats/min, −41 to 22, P = 0.008). Systolic elastance (2.9 mmHg/ml, 0.4–5.4, P = 0.008), arterial elastance (−5.9, −24 to −0.5, P = 0.038), VAC (−0.86, −1.5 to −0.16, P = 0.009) and cardiac mechanical efficiency (0.18, 0.03–0.22, P = 0.008) differences also showed significant modifications.

CONCLUSIONS

In a small case series of patients with single-ventricle physiology, levosimendan showed to improve contractility and optimize VAC, with a reduction of heart rate. Monitoring of VAC and ventricular energetics can be an interesting aspect to improve the management of heart failure in infants with univentricular anatomy.

Population Pharmacokinetics of Milrinone in Infants, Children, and Adolescents

Milrinone is a type 3 phosphodiesterase inhibitor used to improve cardiac output in critically ill infants and children. Milrinone is primarily excreted unchanged in the urine, raising concerns for toxic accumulation in the setting of renal dysfunction of critical illness. We developed a population pharmacokinetic model of milrinone using nonlinear mixed-effects modeling in NONMEM to perform dose-exposure simulations in children with variable renal function. We included children aged <21 years who received intravenous milrinone per clinical care. Plasma milrinone concentrations were measured using a validated liquid chromatography-tandem mass spectrometry assay (range 1-5000 ng/mL). We performed dose-exposure simulations targeting steady-state therapeutic concentrations of 100-300 ng/mL previously established in adults and children with cardiac dysfunction. We simulated concentrations over 48 hours in typical subjects with decreasing creatinine clearance (CrCl), estimated using the updated bedside Schwartz equation. Seventy-four patients contributed 111 plasma samples (concentration range, 4-634 ng/mL). The median (range) postmenstrual age (PMA) was 3.7 years (0-18), and median weight (WT) was 13.1 kg (2.6-157.7). The median serum creatinine and CrCl were 0.5 mg/dL (0.1-3.1) and 117.2 mL/min/1.73 m2 (13.1-261.3), respectively. A 1-compartment model characterized the pharmacokinetic data well. The final model parameterization was: Clearance (L/h) = 15.9*(WT [kg] / 70)0.75 * (PMA1.12 / (67.71.12 +PMA1.12 )*(CrCl / 117)0.522 ; and Volume of Distribution (L) = 32.2*(WT [kg] / 70). A loading dose of 50 µg/kg followed by a continuous infusion of 0.5 µg/kg/min resulted in therapeutic concentrations, except when CrCl was severely impaired at ≤30 mL/min/1.73 m2 . In this setting, a 25 µg/kg loading dose and 0.25 µg/kg/min continuous infusion resulted in therapeutic exposures.

Ventricular-Arterial Coupling in Children and Infants With Congenital Heart Disease After Cardiopulmonary Bypass Surgery: Observational Study

OBJECTIVES

Ventricular-arterial coupling represents the interaction between the left ventricle and the arterial system. Ventricular-arterial coupling is measured as the ratio between arterial elastance and ventricular end-systolic elastance. Scant information is available in critically ill children about these variables. The aim of this study was to prospectively assess ventricular-arterial coupling after pediatric cardiac surgery and evaluate its association with other commonly recorded hemodynamic parameters.

DESIGN

Single-center retrospective observational study.

SETTING

Pediatric cardiac surgery operating room.

PATIENTS

Children undergoing corrective cardiac surgery.

INTERVENTIONS

Hemodynamic monitoring with transesophageal echocardiography.

MEASUREMENTS AND MAIN RESULTS

Twenty-seven patients with biventricular congenital heart disease, who underwent elective cardiac surgery with cardiopulmonary bypass, were enrolled before operating room discharge. Chen single-beat modified method was applied to calculate ventricular-arterial coupling. The median arterial elastance and end-systolic elastance values were 5.9 mm Hg/mL (2.2-9.3 mm Hg/mL) and 4.3 mm Hg/mL (1.9-8.3 mm Hg/mL), respectively. The median ventricular- arterial coupling was 1.2 (1.1-1.6). End-systolic elastance differences between patients with a ventricular-arterial coupling below (low ventricular-arterial coupling) and above (high ventricular-arterial coupling) the median value were -5.2 (95% CI, -6.28 to -0.7; p = 0.008). Differently, arterial elastance differences were -2.1 (95% CI, -5.7 to 1.6; p = 0.19). Ventricular-arterial coupling showed a significant association with pre-ejection time (r, 0.44; p = 0.02), total ejection time (r, -0.41; p = 0.003), cardiac cycle efficiency (r, -0.46; p = 0.02), maximal delta pressure over delta time (r, -0.44; p = 0.02), ejection fraction (r, -0.57; p = 0.01), and systemic vascular resistances indexed (0.56; p = 0.003). After adjustment, total ejection time (p = 0.001), pre-ejection time (p = 0.02), and ejection fraction (p = 0.001) remained independently associated with ventricular-arterial coupling.

CONCLUSIONS

Median ventricular-arterial coupling values in children after cardiac surgery appear high (above 1). Uncoupling was particularly evident in high ventricular-arterial coupling patients who showed the lowest end-systolic elastance values (but not significantly different arterial elastance values) compared with low ventricular-arterial coupling. Ventricular-arterial coupling appears to be inversely proportional to pre-ejection time, total ejection time, and ejection fraction.

Risk Factors for Healthcare-Associated Infections After Pediatric Cardiac Surgery

OBJECTIVES

Healthcare-associated infections after pediatric cardiac surgery are significant causes of morbidity and mortality. We aimed to identify the risk factors for the occurrence of healthcare-associated infections after pediatric cardiac surgery.

DESIGN

Retrospective, single-center observational study.

SETTING

PICU at a tertiary children's hospital.

PATIENTS

Consecutive pediatric patients less than or equal to 18 years old admitted to the PICU after cardiac surgery, between January 2013 and December 2015.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All the data were retrospectively collected from the medical records of patients. We assessed the first surgery during a single PICU stay and identified four common healthcare-associated infections, including bloodstream infection, surgical site infection, pneumonia, and urinary tract infection, according to the definitions of the Centers for Disease Control and Prevention and National Healthcare Safety Network. We assessed the pre-, intra-, and early postoperative potential risk factors for these healthcare-associated infections via multivariable analysis. In total, 526 cardiac surgeries (394 patients) were included. We identified 81 cases of healthcare-associated infections, including, bloodstream infections (n = 30), surgical site infections (n = 30), urinary tract infections (n = 13), and pneumonia (n = 8). In the case of 71 of the surgeries (13.5%), at least one healthcare-associated infection was reported. Multivariable analysis indicated the following risk factors for postoperative healthcare-associated infections: mechanical ventilation greater than or equal to 3 days (odds ratio, 4.81; 95% CI, 1.89-12.8), dopamine use (odds ratio, 3.87; 95% CI, 1.53-10.3), genetic abnormality (odds ratio, 2.53; 95% CI, 1.17-5.45), and delayed sternal closure (odds ratio, 3.78; 95% CI, 1.16-12.8).

CONCLUSIONS

Mechanical ventilation greater than or equal to 3 days, dopamine use, genetic abnormality, and delayed sternal closure were associated with healthcare-associated infections after pediatric cardiac surgery. Since the use of dopamine is an easily modifiable risk factor, and may serve as a potential target to reduce healthcare-associated infections, further studies are needed to establish whether dopamine negatively impacts the development of healthcare-associated infections.

The Perspective of the Intensivist on Inotropes and Postoperative Care Following Pediatric Heart Surgery: An International Survey and Systematic Review of the Literature

Introduction:

Inotropes are frequently being used in children undergoing heart surgery to prevent or treat low cardiac output syndrome (LCOS). There is only limited evidence that inotropes actually positively influence postoperative outcome. Our aim was to describe the current international practice variation in the use of inotropes following congenital heart surgery.

Methods:

We developed an online survey regarding the postoperative use of inotropes. We sent an invitation to all 197 registered members of the Pediatric Cardiac Intensive Care Society (PCICS) to participate in the survey. We also performed a systematic review of the literature.

Results:

Ninety-eight people (50%) responded, representing 62 international centers. Milrinone is routinely used perioperatively by 90 respondents (97%). Adrenaline/epinephrine is routinely used by 43%, dopamine by 36%, dobutamine by 11%, and levosimendan by 6%. Steroids are used routinely by 54% before initiating cardiopulmonary bypass. Vasopressin is used by 44% of respondents. The development of LCOS is monitored with lactate in 99% of respondents, physical examination (98%), intermittent mixed venous saturation (76%), continuous mixed venous saturation (13%), echocardiography (53%), core–peripheral temperature gap (29%), near-infrared spectrometry (25%), and 4% use cardiac output monitors (PiCCO, USCOM). To improve cardiac output, 42% add/increase milrinone, 37% add adrenaline, and 15% add dopamine. Rescue therapy is titrated individually, based on the patients’ pathophysiology. A systematic review of the literature failed to show compelling evidence with regard to the benefit of inotropes.

Conclusions:

Despite the lack of sufficient evidence, milrinone is used by the vast majority of caregivers following congenital heart surgery.