Vasopressin in pediatric shock and cardiac arrest

Low-Dose vasopressin and renal perfusion in pediatric cardiac surgery

Background

Congenital heart surgeries are associated with post-bypass renal and cardiac dysfunctions. The use of low-dose vasopressin has been found to be beneficial in adult cardiac surgeries.

Objective

To assess the hemodynamic and renal effects of patients undergoing on-pump pediatric cardiac surgery under general anesthesia (GA) with low-dose vasopressin infusion.

Design

Prospective randomized controlled study.

Setting

Operation room and ICU, tertiary care teaching hospital.

Patients

Fifty-five pediatric cardiac patients undergoing repair for congenital heart diseases (CHD).

Interventions

Low-dose vasopressin infusion in the study group and placebo in the control group.

Measurements and Main Results

Renal near-infrared spectroscopy (NIRS), serum NGAL, and inflammatory mediators-IL6 and IL8 along with other renal and hemodynamic parameters in the perioperative period were recorded. Diastolic blood pressure (DBP) and cardiac index were significantly higher in the vasopressin group. Inflammatory markers were significantly high in the immediate postoperative period in all patients which later stabilized in the next 48 h but showed similar trends in both groups. Low-dose vasopressin infusion did not improve either renal perfusion or function. The duration of mechanical ventilation and length of hospital stay, the incidence of AKI development, and transfusion requirements were marginally lower in the vasopressin group, although not significant.

Conclusion

Low-dose vasopressin infusion improved hemodynamics and showed a decreased incidence of complications. However, it failed to show any benefit of renal function and overall outcome in pediatric cardiac surgery.

Medication and Fluid Management of Pediatric Sepsis and Septic Shock

Sepsis is a life-threatening response to infection that contributes significantly to neonatal and pediatric morbidity and mortality worldwide. The key tenets of care include early recognition of potential sepsis, rapid intervention with appropriate fluids to restore adequate tissue perfusion, and empiric antibiotics to cover likely pathogens. Vasoactive/inotropic agents are recommended if tissue perfusion and hemodynamics are inadequate following initial fluid resuscitation. Several adjunctive therapies have been suggested with theoretical benefit, though definitive recommendations are not yet supported by research reports. This review focuses on the recommendations for medication and fluid management of pediatric sepsis and septic shock, highlighting issues related to antibiotic choices and antimicrobial stewardship, selection of intravenous fluids for resuscitation, and selection and use of vasoactive/inotropic medications. Controversy remains regarding resuscitation fluid volume and type, antibiotic choices depending upon infectious risks in the patient's community, and adjunctive therapies such as vitamin C, corticosteroids, intravenous immunoglobulin, and methylene blue. We include best practice recommendations based on international guidelines, a review of primary literature, and a discussion of ongoing clinical trials and the nuances of therapeutic choices.

Low vasopressin and progression of neonatal sepsis to septic shock: a prospective cohort study

The study objective was to analyze the association between low plasma vasopressin and progression of sepsis to septic shock in neonates < 34 weeks gestation. Septic neonates of < 34 weeks gestation were consecutively enrolled; moribund neonates and those with major malformations were excluded. Subjects were monitored for progression of sepsis to septic shock over the first 7 days from enrolment. Plasma vasopressin levels and inducible nitric oxide synthase levels were measured at the onset of sepsis (T0), severe sepsis (T1), and septic shock (T2). Primary outcome was plasma vasopressin levels at the point of sepsis in those who progressed to septic shock in comparison with matched nested controls in the non-progression group. Forty-nine (47%) enrolled subjects developed severe sepsis or septic shock. Plasma vasopressin levels (pg/ml) at the onset of sepsis were significantly low in those who progressed to septic shock (median (IQR), 31 (2.5-80) versus 100 (12-156); p = 0.02). After adjusting for confounders, vasopressin levels were independently associated with progression to septic shock (adjusted OR (95% CI), 0.97 (0.96, 0.99); p = 0.01).Conclusion: Preterm septic neonates who progressed to septic shock had suppressed vasopressin levels before the onset of shock. Low vasopressin levels were independently associated with progression to septic shock.What is known:• In animal sepsis models and adult septic patients, exuberant production of nitric oxide metabolites and low vasopressin levels have been reportedly associated with progression to septic shock.• Vasopressin levels have been variably reported as low as well as elevated in children with septic shock.What is New:• Preterm neonates who progressed from sepsis to septic shock had significantly lower levels of vasopressin before the onset of shock in comparison with those who did not progress.• Low vasopressin levels independently predicted the progression from sepsis to septic shock in this population.

Septic shock in pediatrics: the state-of-the-art

OBJECTIVE

Review the main aspects of the definition, diagnosis, and management of pediatric patients with sepsis and septic shock.

SOURCE OF DATA

A search was carried out in the MEDLINE and Embase databases. The articles were chosen according to the authors' interest, prioritizing those published in the last five years.

SYNTHESIS OF DATA

Sepsis remains a major cause of mortality in pediatric patients. The variability of clinical presentations makes it difficult to attain a precise definition in pediatrics. Airway stabilization with adequate oxygenation and ventilation if necessary, initial volume resuscitation, antibiotic administration, and cardiovascular support are the basis of sepsis treatment. In resource-poor settings, attention should be paid to the risks of fluid overload when administrating fluids. Administration of vasoactive drugs such as epinephrine or norepinephrine is necessary in the absence of volume response within the first hour. Follow-up of shock treatment should adhere to targets such as restoring vital and clinical signs of shock and controlling the focus of infection. A multimodal evaluation with bedside ultrasound for management after the first hours is recommended. In refractory shock, attention should be given to situations such as cardiac tamponade, hypothyroidism, adrenal insufficiency, abdominal catastrophe, and focus of uncontrolled infection.

CONCLUSIONS

The implementation of protocols and advanced technologies have reduced sepsis mortality. In resource-poor settings, good practices such as early sepsis identification, antibiotic administration, and careful fluid infusion are the cornerstones of sepsis management.

Effect of vasopressin on a porcine model of persistent pulmonary hypertension of the newborn

BACKGROUND

Persistent pulmonary hypertension of the newborn (PPHN) is due to a failure of pulmonary vascular relaxation. Vasopressin, a systemic vasoconstrictor acting on smooth muscle AVPR1a receptors, is used in treatment of PPHN. We sought to determine acute effects of vasopressin infusion on pulmonary hemodynamics in a large animal model of hypoxic PPHN.

METHODS

PPHN was induced in 6 newborn piglets by 72 h normobaric hypoxia (FiO2 = 0.10); controls were 7 age-matched 3-day-old piglets. Animals were anesthetized and ventilated with central venous and arterial lines, and after stabilization, randomized using a crossover design to normoxic or hypoxic ventilation, then 30 min infusion of 0.0012 U/kg/min vasopressin, followed by 45 min vasopressin washout period. Echocardiographic parameters and oxygen consumption were measured before and after vasopressin. Relaxation to vasopressin was tested in isolated PPHN and control pulmonary arteries by isometric myography. Expression of AVPR1a receptor mRNA was quantified in arterial and myocardial tissues.

RESULTS

Vasopressin did not alleviate hypoxia-responsiveness of PPHN pulmonary circuit. There were no significant differences in pulmonary hypertension, cardiac function indices, or oxygenation indices after vasopressin infusion. Vasopressin did not dilate control or PPHN pulmonary arteries, and AVPR1 was minimally expressed.

CONCLUSIONS

Vasopressin does not have a direct pulmonary vasodilator effect in PPHN, within the timeframe studied.

Cardiovascular Supportive Therapies for Neonates With Asphyxia - A Literature Review of Pre-clinical and Clinical Studies

Asphyxiated neonates often have hypotension, shock, and poor tissue perfusion. Various "inotropic" medications are used to provide cardiovascular support to improve the blood pressure and to treat shock. However, there is incomplete literature on the examination of hemodynamic effects of these medications in asphyxiated neonates, especially in the realm of clinical studies (mostly in late preterm or term populations). Although the extrapolation of findings from animal studies and other clinical populations such as children and adults require caution, it seems appropriate that findings from carefully conducted pre-clinical studies are important in answering some of the fundamental knowledge gaps. Based on a literature search, this review discusses the current available information, from both clinical studies and animal models of neonatal asphyxia, on common medications used to provide hemodynamic support including dopamine, dobutamine, epinephrine, milrinone, norepinephrine, vasopressin, levosimendan, and hydrocortisone.

Vasopressin in Pediatric Critical Care

Vasopressin is a unique hormone with complex receptor physiology and numerous physiologic functions beyond its well-known vascular actions and osmoregulation. While vasopressin has in the past been primarily used in the management of diabetes insipidus and acute gastrointestinal bleeding, an increased understanding of the physiology of refractory shock, and the role of vasopressin in maintaining cardiovascular homeostasis prompted a renewed interest in the therapeutic roles for this hormone in the critical care setting. Identifying vasopressin-deficient individuals for the purposes of assessing responsiveness to exogenous hormone and prognosticating outcome has expanded research into the evaluation of vasopressin and its precursor, copeptin as useful biomarkers. This review summarizes the current evidence for vasopressin in critically ill children, with a specific focus on its use in the management of shock. We outline important considerations and current guidelines, when considering the use of vasopressin or its analogues in the pediatric critical care setting.

Cord blood copeptin concentrations in fetal macrosomia

BACKGROUND/AIM

Excessive fetal growth is associated with increased adiposity and reduced insulin sensitivity at birth. Copeptin, a surrogate marker of arginine vasopressin (AVP) secretion, is upregulated in states of hyperinsulinemia and is considered one of the mediators of insulin resistance. We aimed to investigate cord blood concentrations of copeptin (C-terminal fragment of AVP pro-hormone) in healthy large-for-gestational-age (LGA) infants at term.

METHODS

This prospective study was conducted on 30 LGA (n=30) and 20 appropriate-for-gestational-age (AGA, n=20) singleton full-term healthy infants. Cord blood copeptin and insulin concentrations were determined by ELISA and IRMA, respectively. Infants were classified as LGA or AGA, based on customized birth-weight standards adjusted for significant determinants of fetal growth.

RESULTS

Cord blood copeptin concentrations were similar in LGA cases, compared to AGA controls, after adjusting for delivery mode. However, in the LGA group, cord blood copeptin concentrations positively correlated with birth-weight (r=0.422, p=0.020). In the AGA group, cord blood copeptin concentrations were elevated in cases of vaginal delivery vs elective cesarean section (p=0.003). Cord blood insulin concentrations were higher in LGA cases, compared to AGA controls (p=0.036). No association was recorded between cord blood copeptin concentrations and maternal age, parity, gestational age or fetal gender in both groups.

CONCLUSIONS

Cord blood copeptin concentrations may not be up-regulated in non-distressed LGA infants. However, the positive correlation between cord blood copeptin concentrations and birth-weight in the LGA group may point to the documented association between AVP release and increased fat deposition. Vaginal delivery vs elective cesarean section is accompanied by a marked stress-related increase of cord blood copeptin concentrations.

Postoperative management of heart failure in pediatric patients

Low cardiac output syndrome (LCOS) is a well-described entity occurring in 25-65% of pediatric patients undergoing open-heart surgery. With judicious intensive care management of LCOS, most patients have an uncomplicated postoperative course, and within 24 h after cardiopulmonary bypass, the cardiac function returns back to baseline. Some patients have severe forms of LCOS not responsive to medical management alone, requiring temporary mechanical circulatory support to prevent end-organ injury and to decrease myocardial stress and oxygen demand. Occasionally, cardiac function does not recover and heart transplantation is necessary. Long-term mechanical circulatory support devices are used as a bridge to transplantation because of limited availability of donor hearts. Experience in usage of continuous flow ventricular assist devices in the pediatric population is increasing.

[Septic shock in intensive care units. Current focus on treatment]

Essential therapeutic principles in children with septic shock persist over time, although some new concepts have been recently incorporated, and fully awareness of pediatricians and intensivists is essential. Fluid resuscitation is a fundamental intervention, but the kind of ideal fluid has not been established yet, as each of these interventions has specific limitations and there is no evidence supportive of the superiority of one type of fluid. Should septic shock persists despite adequate fluid resuscitation, the use of inotropic medication and/or vasopressors is indicated. New vasoactive drugs can be used in refractory septic shock caused by vasopressors, and the use of hydrocortisone should be considered in children with suspected adrenal insufficiency, as it reduces the need for vasopressors. The indications for red blood cells transfusion or the optimal level of glycemia are still controversial, with no consensus on the threshold value for the use of these blood products or the initiation of insulin administration, respectively. Likewise, the use of high-volume hemofiltration is a controversial issue and further study is needed on the routine recommendation in the course of septic shock. Nutritional support is crucial, as malnutrition is a serious complication that should be properly prevented and treated. The aim of this paper is to provide update on the most recent advances as concerns the treatment of septic shock in the pediatric population.

Effect of corticosteroids on arginine vasopressin after pediatric cardiac surgery

INTRODUCTION

Arginine vasopressin's (AVP) efficacy in the treatment of refractory hypotension is, in part, dependent upon preinfusion endogenous AVP concentration. Corticosteroids, also commonly used to treat refractory hypotension, have been shown to suppress endogenous AVP release. We aimed to determine if corticosteroids affect endogenous AVP concentrations in children recovering from cardiac surgery.

MATERIALS AND METHODS

We reviewed the records of children who underwent cardiac surgery between January 2008 and January 2009 and had AVP concentrations available as part of a prior prospective study. Doses of hydrocortisone, methylprednisolone, and dexamethasone administered within the first 48 hours after cardiopulmonary bypass were quantitated. Multivariable linear regression was performed to determine if corticosteroids had a significant effect on 48-hour plasma AVP concentration.

RESULTS

Sixty-nine children with plasma AVP concentrations available were reviewed, 34 (49%) of which received corticosteroids within 48 hours after cardiopulmonary bypass. On multivariable regression, greater number of corticosteroid doses but not cumulative corticosteroid dosage was significantly associated with low 48-hour AVP concentration (β=-4.0; 95% confidence intervals, -6.5 to -1.4).

CONCLUSIONS

Children who receive multiple doses of corticosteroids after cardiac surgery, regardless of potency, are likely to have low endogenous AVP concentrations. Children who remain unstable despite corticosteroids may respond favorably to exogenous AVP therapy.

Clinical response to arginine vasopressin therapy after paediatric cardiac surgery

OBJECTIVE

To describe the haemodynamic response of children who receive arginine vasopressin for haemodynamic instability after cardiac surgery and to identify clinical variables associated with a favourable response. Materials and Methods We reviewed patients less than or equal to 6 years undergoing open heart surgery in our institution between January, 2009 and July, 2010 who received arginine vasopressin during the first 7 days post operation. Favourable responders were defined as those in whom blood pressure was increased or maintained and catecholamine score was decreased, or blood pressure was increased by greater than or equal to 10% of baseline and catecholamine score was unchanged at 6 hours following arginine vasopressin initiation.

RESULTS

Of the 34 patients identified, 17 (50%) patients responded favourably to arginine vasopressin. At 6 hours, the mean blood pressure was increased by 32.2% in responders as compared with 4.6% in non-responders, with a p-value less than 0.001. The mean catecholamine score decreased by 30.1% in responders and increased by 7.6% in non-responders, with a p-value less than 0.001. Anthropometric, demographic, and intra-operative variables were similar in both groups, as was maximum dose of arginine vasopressin. The median time after arrival to the intensive care unit at which arginine vasopressin was initiated, however, was later in those who responded, 20 hours as compared with those who did not, 6 hours, with a p-value equal to 0.032.

CONCLUSIONS

Arginine vasopressin therapy led to haemodynamic improvement in only half of the children in this study, and improvement was more likely to occur if arginine vasopressin was initiated after the post-operative night.

Plasma copeptin concentration and outcome after pediatric traumatic brain injury

Higher plasma copeptin level has been associated with poor outcomes of critical illness. The present study was undertaken to investigate the plasma copeptin concentrations in children with traumatic brain injury (TBI) and to analyze the correlation of copeptin with disease outcome. Plasma copeptin concentrations of 126 healthy children and 126 children with acute severe TBI were measured by enzyme-linked immunosorbent assay. Twenty-one patients (16.7%) died and 38 patients (30.2%) had an unfavorable outcome (Glasgow Outcome Scale score of 1-3) at 6 months. Plasma copeptin level was obviously higher in patients than in healthy children (46.2±20.8 pmol/L vs. 9.6±3.0 pmol/L, P<0.001). Plasma copeptin level was identified as an independent predictor for 6-month mortality [odds ratio (OR) 1.261, 95% confidence interval (CI) 1.112-1.538, P=0.005] and unfavorable outcome (OR 1.313, 95% CI 1.146-1.659, P=0.003). The predictive value of copeptin was similar to that of Glasgow Coma Scale (GCS) score for 6-month mortality [area under curve (AUC) 0.832, 95% CI 0.755-0.892 vs. AUC 0.873, 95% CI 0.802-0.926, P=0.412] and unfavorable outcome (AUC 0.863, 95% CI 0.790-0.918 vs. AUC 0.885, 95% CI 0.816-0.935, P=0.596). Copeptin improved the AUC of GCS score for 6-month unfavorable outcome (AUC 0.929, 95% CI 0.869-0.967, P=0.013), but not for 6-month mortality (AUC 0.887, 95% CI 0.818-0.936, P=0.600). Thus, plasma copeptin level represents a novel biomarker for predicting 6-month clinical outcome in children with TBI.

Vasopressin and copeptin levels in children with sepsis and septic shock

PURPOSE

Levels of vasopressin and its precursor copeptin in pediatric sepsis and septic shock are not well defined. The main aim of this study is to compare the serum levels of vasopressin and copeptin in children with septic shock or sepsis and in healthy children. We hypothesized that vasopressin and copeptin levels are elevated in early and late stages of pediatric septic shock.

METHODS

Three groups were included: healthy children, children with clinical diagnosis of sepsis, and children admitted to the pediatric intensive care unit (PICU) with diagnosis of sepsis shock. Blood samples were drawn from children in all groups within 24 h of admission. For the septic shock group, additional samples at 24-h intervals were drawn up to 120 h after PICU admission. We used competitive immunoassays to determine vasopressin and copeptin levels.

RESULTS

There were 70 children in the control group, 53 children in the sepsis group, and 13 in the septic shock group. At baseline, there was a difference in median vasopressin levels [60.9 (Interquartile range: 32.3, 138.0) vs. 141.1 (45.2, 542) vs. 326 (55.6, 399) pg/mL, p < 0.05], but there was no difference in copeptin levels [1.2 (0.8, 1.8) vs. 1.5 (1.0, 2.2) vs. 0.9 (0.8, 1.2) ng/mL, p = 0.14] between the three groups. There was no difference in vasopressin and copeptin levels in early and late stages of pediatric septic shock.

CONCLUSIONS

Baseline vasopressin levels were different between the three groups. In pediatric septic shock, vasopressin and copeptin levels are not robust markers for severity and clinical outcomes.

The pediatric cardiology pharmacopeia: 2013 update

The use of medications plays a pivotal role in the management of children with heart diseases. Most children with increased pulmonary blood flow require chronic use of anticongestive heart failure medications until more definitive interventional or surgical procedures are performed. The use of such medications, particularly inotropic agents and diuretics, is even more amplified during the postoperative period. Currently, children are undergoing surgical intervention at an ever younger age with excellent results aided by advanced anesthetic and postoperative care. The most significant of these advanced measures includes invasive and noninvasive monitoring as well as a wide array of pharmacologic agents. This review update provides a medication guide for medical practitioners involved in care of children with heart diseases.

Early initiation of arginine vasopressin infusion in neonates after complex cardiac surgery

OBJECTIVE

To describe our experience with low-dose arginine vasopressin infusions (0.0003 U/kg/min) initiated in the operating room after the Norwood procedure or arterial switch operation.

DESIGN

Retrospective cohort study of 37 consecutive neonates.

SETTING

Pediatric cardiovascular intensive care unit in a tertiary hospital.

SUBJECTS

Nineteen patients that received low-dose arginine vasopressin infusion instituted in the operating room (arginine vasopressin+) were compared to 18 patients that did not receive early arginine vasopressin infusion (arginine vasopressin-).

INTERVENTIONS

None.

RESULTS

When comparing arginine vasopressin+ and arginine vasopressin- in the first 24 hrs after cardiovascular intensive care unit admission, there was no difference in demographic variables, heart rate, blood pressure, central venous pressure, maximum lactate, maximum arterial and central venous saturation difference, urine output, chest tube output, or peritoneal drain output. Mean fluid resuscitation in the first 24 hrs was significantly lower in the arginine vasopressin+ group compared to the arginine vasopressin- group (182 ± 61 mL/kg vs. 223 ± 53 mL/kg, p = .03). The arginine vasopressin+ group also reached median net negative cumulative fluid balance sooner (55 hrs: interquartile range 45, 74 vs. 76 hrs: interquartile range 69, 92; p = .02). Median maximum inotrope score in the first 24 hrs was significantly lower in arginine vasopressin+ (9: interquartile range 5, 12.5 vs. 16.5: interquartile range 10.3, 22.1; p = .02). There was a nonsignificant trend toward shorter duration of mechanical ventilation and cardiovascular intensive care unit length of stay in the arginine vasopressin+ group. The lowest serum sodium in the first 48 hrs was significantly lower in arginine vasopressin+ (132 vs. 137 mmol/L, p = .01).

CONCLUSION

Low-dose arginine vasopressin infusion initiated in the operating room after complex neonatal cardiac surgery was associated with decreased fluid resuscitation and catecholamine requirements in the first 24 postoperative hours.

Management of the postoperative pediatric cardiac surgical patient

OBJECTIVE

To review the salient aspects and latest advances in the management of the postoperative pediatric cardiac patient.

DATA SOURCE

A Medline-based literature source.

CONCLUSION

The practice of pediatric cardiac intensive care has evolved considerably over the last several years. These efforts are the result of a collaborative effort from all subspecialties involved in the care of pediatric patients with congenital heart disease. Discoveries and innovations that are representative of this effort include the extension of cerebral oximetry from the operating room into the critical care setting; mechanical circulatory devices designed for pediatric patients; and surgery in very low birth weight neonates. Advances such as these impact postoperative management and make the field of pediatric cardiac intensive care an exciting, demanding, and evolving discipline, necessitating the ongoing commitment of various disciplines to pursue a greater understanding of disease processes and how to best go about treating them.

Management of septic shock

Septic shock is an important cause of mortality in children with sepsis. The incidence of septic shock is 2-4% of admissions in western pediatric intensive care units and 40%-67% for Indian PICUs. Early goal-directed resuscitation that includes aggressive fluid resuscitation of up to 60 mL/kg as boluses of 20 mL/kg by IV push, to achieve desired heart rates and blood pressure, has emerged as mainstay of treatment in the initial stage. Crystalloids are the preferred fluids, while colloids may be used in some situations. Fluid refractory shock warrants use of vasoactive drugs. Dopamine is the first choice. Dobutamine and low dose epinephrine are the preferred inotropic drugs while nor-epinephrine is a vasopressor. Children with cold shock and normal blood pressure may benefit from nitrosodilators like nitroprusside and nitroglycerine. Inodilators such as milrinone are also useful in this situation. Targeting clinical therapeutic end-points assists the management. Good supportive care is also essential for improving the outcomes.

Copeptin concentration in cord blood in infants with early-onset sepsis, chorioamnionitis and perinatal asphyxia

Background

Vasopressin is one of the most important physiological stress and shock hormones. Copeptin, a stable vasopressin precursor, is a promising sepsis marker in adults. In contrast, its involvement in neonatal diseases remains unknown. The aim of this study was to establish copeptin concentrations in neonates of different stress states such as sepsis, chorioamnionitis and asphyxia.

Methods

Copeptin cord blood concentration was determined using the BRAHMS kryptor assay. Neonates with early-onset sepsis (EOS, n = 30), chorioamnionitis (n = 33) and asphyxia (n = 25) were compared to a control group of preterm and term (n = 155) neonates.

Results

Median copeptin concentration in cord blood was 36 pmol/l ranging from undetectable to 5498 pmol/l (IQR 7 - 419). Copeptin cord blood concentrations were non-normally distributed and increased with gestational age (p < 0.0001). Neonates born after vaginal compared to cesarean delivery had elevated copeptin levels (p < 0.0001). Copeptin correlated strongly with umbilical artery pH (Spearman's Rho -0.50, p < 0.0001), umbilical artery base excess (Rho -0.67, p < 0.0001) and with lactate at NICU admission (Rho 0.54, p < 0.0001). No difference was found when comparing copeptin cord blood concentrations between neonates with EOS and controls (multivariate p = 0.30). The highest copeptin concentrations were found in neonates with asphyxia (median 993 pmol/l). Receiver-operating-characteristic curve analysis showed that copeptin cord blood concentrations were strongly associated with asphyxia: the area under the curve resulted at 0.91 (95%-CI 0.87-0.96, p < 0.0001). A cut-off of 400 pmol/l had a sensitivity of 92% and a specifity of 82% for asphyxia as defined in this study.

Conclusions

Copeptin concentrations were strongly related to factors associated with perinatal stress such as birth acidosis, asphyxia and vaginal delivery. In contrast, copeptin appears to be unsuitable for the diagnosis of EOS.

Relative deficiency of arginine vasopressin in children after cardiopulmonary bypass

OBJECTIVE

To describe changes in plasma arginine vasopress in concentration in children following cardiopulmonary bypass and determine whether, in some patients, plasma arginine vasopressin remains relatively low despite hemodynamic instability.

DESIGN

Prospective observational study.

SETTING

Pediatric intensive care unit at a tertiary care university hospital.

PATIENTS

One hundred twenty patients ≤ 18 yrs of age undergoing open heart surgery requiring cardiopulmonary bypass at Children's Hospital of Michigan between January 2008 and January 2009.

INTERVENTIONS

Blood samples were collected before cardiopulmonary bypass and 4, 24, and 48 hrs after cardiopulmonary bypass for measurement of plasma arginine vasopressin concentration.

MEASUREMENTS AND MAIN RESULTS

Mean plasma arginine vasopressin (pg/mL) for all patients was 21 ± 63 before cardiopulmonary bypass and 80 ± 145, 43 ± 79, and 19 ± 25 at 4, 24, and 48 hrs, respectively, after cardiopulmonary bypass. Patients with plasma arginine vasopressin below the lower quartile (< 9.2 pg/mL) at 4 hrs after cardiopulmonary bypass (n = 29), labeled group A, were examined separately and compared with the rest of the study population, labeled group B. Mean plasma arginine vasopressin was 4.9 ± 2.6 in group A at 4 hrs after cardiopulmonary bypass, statistically unchanged from its baseline mean plasma arginine vasopressin of 5.0 ± 10.4 (p = .977). Mean plasma arginine vasopressin in group B was 104 ± 160 at 4 hrs after cardiopulmonary bypass. Mean plasma arginine vasopressin of group A was also significantly lower as compared with group B before and 24 and 48 hrs after cardiopulmonary bypass. Hemodynamics, inotrope score, and serum sodium did not differ between groups at any time point. Plasma arginine vasopressin was measured immediately before exogenous arginine vasopressin administration in 10 patients; only those (n = 3) with hemodynamic instability and relatively low plasma arginine vasopressin concentration (< 9.2 pg/mL) had notable hemodynamic improvement.

CONCLUSIONS

In some children undergoing open heart surgery, plasma arginine vasopressin concentration is relatively low at baseline and remains low after cardiopulmonary bypass regardless of hemodynamic stability and serum osmolality. These children are likely the optimal candidates for exogenous arginine vasopressin should hemodynamic compromise occur.

[Terlipressin as rescue therapy in hypercyanotic spells of Fallot tetralogy]

Hypercyanotic spells, very common in Fallot tetralogy, are a medical emergency and can cause neurological damage or even death. They are produced by a dramatic decrease in pulmonary blood flow, with increased right-left shunt and a drop in systemic arterial saturation. Treatment includes alpha.-agonists (such as methoxamine or phenylephrine), which increase peripheral resistance, forcing the entry of blood through the infundibulum. However, they are not available in our environment. An alternative, still not described, could be terlipressin, a potent vasoconstrictor. We report a three months old infant, with Fallot tetralogy and hypoplastic pulmonary branches, who developed a severe hypoxaemic crisis during postoperative palliative surgery (Blalock-Taussig), no responsive to standard therapy. The administration of terlipressin in three hypercyanotic spells, was effective and reversed them, with a significant and sustained increase in arterial saturation. Although there is still no evidence, terlipressin may be an alternative to alpha.-agonists in these patients.

Vasopressin in pediatric vasodilatory shock: a multicenter randomized controlled trial

RATIONALE

Vasopressin has been proposed as a potent vasoactive agent in the treatment of vasodilatory shock in adults and children. The objective of this trial was to evaluate the efficacy and safety of vasopressin as an adjunctive agent in pediatric vasodilatory shock.

METHODS

In this multicenter, double-blind trial, children with vasodilatory shock were randomized to receive low-dose vasopressin (0.0005-0.002 U/kg/min) or placebo in addition to open-label vasoactive agents. Vasoactive infusions were titrated to clinical endpoints of adequate perfusion. The primary outcome was time to vasoactive-free hemodynamic stability. Secondary outcomes included mortality, organ-failure-free days, length of critical care unit stay, and adverse events.

MEASUREMENTS AND MAIN RESULTS

Sixty-five of 69 children (94%) who were randomized received the study drug (33 vasopressin, 32 placebo) and were included in the analysis. There was no significant difference in the primary outcome between the vasopressin and placebo groups (49.7 vs. 47.1 hours; P = 0.85). There were 10 deaths (30%) in the vasopressin group and five (15.6%) in the placebo group (relative risk, 1.94; 95% confidence interval, 0.75-5.05; P = 0.24). There were no significant differences with respect to organ failure-free days (22 vs. 25.5 days; P = 0.11), ventilator-free days (16.5 23 days; P = 0.15), length of stay (8 vs. 8.5 days; P = 0.93), or adverse event rate ratios (12.0%; 95% confidence interval, -2.6 to 26.7; P = 0.15).

CONCLUSIONS

Low-dose vasopressin did not demonstrate any beneficial effects in this pediatric trial. Although not statistically significant, there was a concerning trend toward increased mortality. Clinical trial registered with www.controlled-trials.com (ISRCTN11597444).

Terlipressin for Children with Extremely Low Cardiac Output After Open Heart Surgery

Background:

Terlipressin, a long-acting analog of vasopressin, has been used successfully in patients with extremely low cardiac output, but its application in children following open heart surgery is limited.

Objective:

To describe our experience using terlipressin in children with extremely low cardiac output after open heart surgery.

Methods:

Records were reviewed of all pediatric patients between January 2003 and December 2005 who had undergone open heart surgery, experienced extremely low cardiac output, and were treated with terlipressin as rescue therapy. Mean arterial blood pressure, heart rate, urine output, and lactate and oxygenation index values were retrieved and analyzed when available.

Results:

Twenty-nine children who were considered gravely ill despite conventional vasoactive agents received terlipressin as rescue therapy, which rapidly yielded significant improvements in all measured hemodynamic and respiratory indices. Mean ± SD arterial blood pressure increased significantly, from 49 ± 17 to 57 ± 16 mm Hg after 10 minutes (p = 0.004) and to 64 ± 15 mm Hg 24 hours after treatment onset (p = 0.001). Twenty-four hours following terlipressin administration, urine output increased from 1.5 ± 2.1 to 3.0 ± 2.3 mL/kg/h (p = 0.001), the oxygenation index decreased from 16.5 ± 27.9 to 9.5 ± 16.7 in the survivors (p = 0.023), and the inotropic score decreased from 41.9 ± 19.9 to 32.6 ± 18.8 (p = 0.009).

Conclusions:

Terlipressin caused significant improvement in hemodynamic, respiratory, and renal indices in children with extremely low cardiac output after open heart surgery. Further controlled studies are needed to confirm the drug's safety and efficacy in this population.

Pilot safety study of low-dose vasopressin in non-septic critically ill children

OBJECTIVE

To assess the safety of low-dose vasopressin infusion in critically ill children requiring prolonged mechanical ventilation (MV) at risk of developing sedation/analgesia-related hypotension.

METHOD

Randomized pilot safety study in children expected to require MV for at least 3 days. Children received either vasopressin (0.0005 U/kg/min) or sodium chloride (0.9%) infusion for a period of 48 h. Haemodynamic variables, urine output and serum electrolytes were closely monitored and analyzed.

RESULTS

Twelve children in each group had similar baseline characteristics. Vasopressin infusion was associated with an 8 mmol/L fall in serum sodium concentration (p < 0.01) and with higher incidence of hyponatraemia (8 vs. 66%, p < 0.01). In normotensive children, low-dose vasopressin also induced a reversible decrease in urine output, and acutely increased blood pressure (p < 0.01). After stopping the vasopressin there was rebound hypotension (p < 0.01).

CONCLUSION

Low-dose vasopressin infusion in haemodynamically stable, but critically ill, children is associated with reduction in urine output and decreased serum sodium level, yielding a high incidence of hyponatraemia. We conclude that these effects limit further study of prophylactic vasopressin for sedation-related hypotension in a randomized controlled trial.

Vasopressin in the pediatric cardiac intensive care unit: Myth or reality

Pediatric cardiac surgery is undergoing a metamorphosis, with more and more critical patients being operated in our country today. Although the principles of physiology have not changed, it is imperative that care providers continue to stay abreast with developments and newer drugs that may help modify the outcome. The team dynamics have also become more complex, which necessitates the need for all care providers (surgeons, cardiologists, anesthesiologists, and intensivists) to better understand the interactions and benefits of newer drugs. Vasopressin has been used in our adult patients for more than a decade and recently has found its rightful place in the pediatric armoury. The objective of this article is to review the physiology of vasopressin and the rationale of its use in critically ill children with shock, in context of the available published data.