Evaluation of Sodium Nitroprusside Toxicity in Pediatric Cardiac Surgical Patients

Treatment of Hypertension in Children

Hypertension is a real problem in children. It shows a tracking behaviour, representing a key risk factor for hypertension, cardiovascular disease, and end-organ failure in adulthood. However, the importance of addressing arterial hypertension in children is not limited to its risk of tracking into adulthood. Thus, early detection and management are crucial. Hypertension may be primary or due to secondary causes, and identification of this distinction is very important for the treatment setting. Importantly, the management of hypertension in children is crucial to prevent the well-known cardiovascular effects in adulthood. As demonstrated in the literature, healthy eating habits, together with regular physical activity, can have a major impact on reducing high blood pressure and preventing organ damage in children and adolescents. However, suppose these are not sufficient to treat hypertension. In that case, if patients are symptomatic and/or have additional metabolic conditions such as obesity, type diabetes mellitus, or chronic kidney disease, anti-hypertensive medication must be started. Recent guidelines have provided clear guidance on the treatment of hypertension and hypertensive crisis in pediatric age. On the other hand, there are currently few specific recommendations on the treatment of isolated nocturnal hypertension and treatment- resistant hypertension. This review aims to summarize the most recent recommendations for the treatment of hypertension and hypertensive crisis in children and the last years' knowledge and experience in treating childhood isolated nocturnal hypertension and resistant hypertension of childhood.

Nicardipine Is a Safe, Efficacious, and Cost-Effective Antihypertensive for Neonates and Young Infants Undergoing Cardiac Surgery

OBJECTIVE

The use of nicardipine in congenital cardiac surgery has been guarded given the calcium sensitivity of immature myocardium and paucity of clinical data. Reports of nicardipine use have excluded neonates with single ventricles. The goal of this study was to compare the use of nicardipine and sodium nitroprusside for postoperative blood pressure control in young patients recovering from cardiac surgery.

METHODS

All neonates (<30 days) and young infants (31-180 days) who received either sodium nitroprusside or nicardipine as first-line therapy for blood pressure control were retrospectively reviewed. Some patients had multiple index operations and each index operation was counted separately regarding treatment with sodium nitroprusside or nicardipine.

RESULTS

A total of 59 patients underwent 70 procedures (24 as neonates and 46 as infants). Nicardipine was administered as initial therapy following 33 procedures (n = 28 patients), and sodium nitroprusside was administered as initial therapy following 37 index procedures (n = 31 patients). The duration of treatment was longer (P = .025) when sodium nitroprusside was the initial treatment. Five (15%) patients that received nicardipine required a second blood pressure management agent, and seven (19%) patients that received sodium nitroprusside required a second agent (P = .66). No adverse events related to titratable antihypertensive therapy were recorded in any treatment group. The use of nicardipine resulted in significant medication cost reduction. Based on average wholesale price, patient costs for sodium nitroprusside use were $182,952 ($5,544/pt), while costs for nicardipine were only $24,960 ($780/pt).

CONCLUSIONS

Nicardipine can be safely used as a first-line antihypertensive in infants. The use of nicardipine as initial antihypertensive therapy rather than sodium nitroprusside can lead to a significant reduction in medication costs without jeopardizing clinical outcomes.

Management of Hypertensive Crises in Children: A Review of the Recent Literature

Hypertensive emergency is a life-threatening condition associated with severe hypertension and organ damage, such as neurological, renal or cardiac dysfunction. The most recent guidelines on pediatric hypertension, the 2016 European guidelines and the 2017 American guidelines, provide recommendations on the management of hypertensive emergencies, however in pediatric age robust literature is lacking and the available evidence often derives from studies conducted in adults. We reviewed PubMed and Cochrane Library from January 2017 to July 2021, using the following search terms: "hypertension" AND "treatment" AND ("emergency" OR "urgency") to identify the studies. Five studies were analyzed, according to our including criteria. According to the articles reviewed in this work, beta-blockers seem to be safe and effective in hypertensive crises, more than sodium nitroprusside, although limited data are available. Indeed, calcium-channel blockers seem to be effective and safe, in particular the use of clevidipine during the neonatal age, although limited studies are available. However, further studies should be warranted to define a univocal approach to pediatric hypertensive emergencies.

A systematic review of the evidence supporting post-operative medication use in congenital heart disease

BACKGROUND

Targeted drug development efforts in patients with CHD are needed to standardise care, improve outcomes, and limit adverse events in the post-operative period. To identify major gaps in knowledge that can be addressed by drug development efforts and provide a rationale for current clinical practice, this review evaluates the evidence behind the most common medication classes used in the post-operative care of children with CHD undergoing cardiac surgery with cardiopulmonary bypass.

METHODS

We systematically searched PubMed and EMBASE from 2000 to 2019 using a controlled vocabulary and keywords related to diuretics, vasoactives, sedatives, analgesics, pulmonary vasodilators, coagulation system medications, antiarrhythmics, steroids, and other endocrine drugs. We included studies of drugs given post-operatively to children with CHD undergoing repair or palliation with cardiopulmonary bypass.

RESULTS

We identified a total of 127 studies with 51,573 total children across medication classes. Most studies were retrospective cohorts at single centres. There is significant age- and disease-related variability in drug disposition, efficacy, and safety.

CONCLUSION

In this study, we discovered major gaps in knowledge for each medication class and identified areas for future research. Advances in data collection through electronic health records, novel trial methods, and collaboration can aid drug development efforts in standardising care, improving outcomes, and limiting adverse events in the post-operative period.

An evidence-based review of the use of vasoactive and inotropic medications in post-operative paediatric patients after cardiac surgery with cardiopulmonary bypass from 2000 to 2020

BACKGROUND

Infants with moderate-to-severe CHD frequently undergo cardiopulmonary bypass surgery in childhood. Morbidity and mortality are highest in those who develop post-operative low cardiac output syndrome. Vasoactive and inotropic medications are mainstays of treatment for these children, despite limited evidence supporting their use.

METHODS

To help inform clinical practice, as well as the conduct of future trials, we performed a systematic review of existing literature on inotropes and vasoactives in children after cardiac surgery using the PubMed and EMBASE databases. We included studies from 2000 to 2020, and the patient population was defined as birth - 18 years of age. Two reviewers independently reviewed studies to determine final eligibility.

RESULTS

The final analysis included 37 papers. Collectively, selected studies reported on 12 different vasoactive and inotropic medications in 2856 children. Overall evidence supporting the use of these drugs in children after cardiopulmonary bypass was limited. The majority of studies were small with 30/37 (81%) enrolling less than 100 patients, 29/37 (78%) were not randomised, and safety and efficacy endpoints differed widely, limiting the ability to combine data for meta-analyses.

CONCLUSION

Vasoactive and inotropic support remain critical parts of post-operative care for children after cardiopulmonary bypass surgery. There is a paucity of data for the selection and dosing of vasoactives and inotropes for these patients. Despite the knowledge gaps that remain, numerous recent innovations create opportunities to rethink the conduct of clinical trials in this high-risk population.

The Use of Clevidipine for Hypertension in Pediatric Patients Receiving Mechanical Circulatory Support

OBJECTIVES

Limited data exist regarding the management of hypertension in pediatric patients on mechanical circulatory support. Hypertension is a known risk factor for stroke and low cardiac output in patients requiring mechanical circulatory support and a narrow therapeutic window of blood pressure is often targeted. Traditional short-acting infusions to treat hypertension, such as sodium nitroprusside, may lead to accumulation of toxic metabolites in patients with renal dysfunction. Our primary objective was to describe use of clevidipine, a continuous short-acting calcium channel blocking medication, for blood pressure control in pediatric patients on mechanical circulatory support.

DESIGN

Single-center retrospective cohort study.

SETTING

A 26-bed quaternary cardiovascular ICU in a university-based pediatric hospital in California.

PATIENTS

Mechanical circulatory support patients admitted to cardiovascular ICU who received clevidipine infusions between October 1, 2016, and March 31, 2019.

INTERVENTIONS

Clevidipine infusion.

MEASUREMENTS AND MAIN RESULTS

Data from a cohort of 38 patients who received a total of 45 clevidipine infusions were reviewed. The cohort had a median age of 2.7 years and included neonates. No patient had record of hypotensive events, code events, or received low-dose epinephrine or code-dosed epinephrine related to a clevidipine infusion. Median duration of clevidipine infusion was 4.1 days (1.5-9.2 d). Eleven patients transitioned from clevidipine to enteral antihypertensive agents, and 26 clevidipine infusions were administered as a single agent without sodium nitroprusside. Seven patients were switched from sodium nitroprusside to clevidipine to avoid cyanide toxicity, a majority of whom had elevated serum creatinine.

CONCLUSIONS

In this pediatric cardiac cohort, clevidipine infusions were effective at hypertension management and were not associated with hypotensive or code events. This report details the largest cohort and longest duration of clevidipine administration within a pediatric population and did not demonstrate hypotensive events, even among neonatal populations. Clevidipine may be a reasonable cost-effective alternative antihypertensive medication compared to traditional short-acting agents.

Pharmacologic Control of Blood Pressure in Infants and Children

Alterations in blood pressure are common during the perioperative period in infants and children. Perioperative hypertension may be the result of renal failure, volume overload, or activation of the sympathetic nervous system. Concerns regarding end-organ effects or postoperative bleeding may mandate regulation of blood pressure. During the perioperative period, various pharmacologic agents have been used for blood pressure control including sodium nitroprusside, nitroglycerin, β-adrenergic antagonists, fenoldopam, and calcium channel antagonists. The following manuscript outlines the commonly used pharmacologic agents for perioperative BP including dosing regimens and adverse effect profiles. Previously published clinical trials are discussed and efficacy in the perioperative period reviewed.

Labetalol Infusion Attenuates Paradoxical Hypertension and Decreases Plasma Renin Activity After Repair of Coarctation of the Aorta in Children

OBJECTIVE

Paradoxical hypertension after repair of coarctation of the aorta in children is associated with the release of catecholamines and activation of the renin-angiotensin system. The objective of the present study was to describe the effects of labetalol infusion on blood pressure, plasma catecholamine levels, and plasma renin activity in a series of children undergoing repair of coarctation of the aorta.

DESIGN

Prospective, observational cohort study.

SETTING

Tertiary children's hospital with university affiliation.

PARTICIPANTS

The study was comprised of 15 consecutive children older than 1 year undergoing repair of coarctation of the aorta.

INTERVENTIONS

Intravenous infusion of labetalol, up to 20 µg/kg/min, was administered when patients became hypertensive after release of the aortic cross-clamp. Supplementation with nitroprusside was allowed as needed.

MEASUREMENTS AND MAIN RESULTS

Blood pressure was maintained below baseline values throughout the labetalol infusion. Plasma norepinephrine increased from 160 ± 81 pg/mL (preoperative) to 657 ± 268 pg/mL (6 h after release of aortic cross-clamp). Plasma renin activity decreased from 16.6 ± 9.7 ng/kg/h (at cross-clamp release) to 2.2 ± 2.2 ng/kg/h (6 h after cross-clamp release). Nitroprusside was added for 12 patients, at a highest mean dose of 2.4 ± 2.5 μg/kg/min.

CONCLUSIONS

Labetalol inhibited activation of the renin-angiotensin system and helped control paradoxical hypertension after coarctation repair in children.

A Practical Guide to the Management of Severe Hypertension in Children

Severe hypertension in children may result in life-threatening complications. Although there has not been extensive research in this area in children, and recommendations are mostly derived from adult data, in the last few years, there have been more pediatric studies on the safety and effectiveness of antihypertensives. The clinical presentation of a child with severe hypertension varies and may be completely asymptomatic or include signs and symptoms of end-organ damage. Treatment of a child with severe hypertension is emergent and should be done concomitantly with the evaluation.

Tumor Homing Reactive Oxygen Species Nanoparticle for Enhanced Cancer Therapy

Multifunctional nanoparticles that carry chemotherapeutic agents can be innovative anticancer therapeutic options owing to their tumor-targeting ability and high drug-loading capacity. However, the nonspecific release of toxic DNA-intercalating anticancer drugs from the nanoparticles has significant side effects on healthy cells surrounding the tumors. Herein, we report a tumor homing reactive oxygen species nanoparticle (THoR-NP) platform that is highly effective and selective for ablating malignant tumors. Sodium nitroprusside (SNP) and diethyldithiocarbamate (DDC) were selected as an exogenous reactive oxygen species (ROS) generator and a superoxide dismutase 1 inhibitor, respectively. DDC-loaded THoR-NP, in combination with SNP treatment, eliminated multiple cancer cell lines effectively by the generation of peroxynitrite in the cells (>95% cell death), as compared to control drug treatments of the same concentration of DDC or SNP alone (0% cell death). Moreover, the magnetic core (ZnFe₂O₄) of the THoR-NP can specifically ablate tumor cells (breast cancer cells) via magnetic hyperthermia, in conjunction with DDC, even in the absence of any exogenous RS supplements. Finally, by incorporating iRGD peptide moieties in the THoR-NP, integrin-enriched cancer cells (malignant tumors, MDA-MB-231) were effectively and selectively killed, as opposed to nonmetastatic tumors (MCF-7), as confirmed in a mouse xenograft model. Hence, our strategy of using nanoparticles embedded with ROS-scavenger-inhibitor with an exogenous ROS supplement is highly selective and effective cancer therapy.

Nicardipine for the Treatment of Neonatal Hypertension During Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is one of the primary reasons systemic hypertension is experienced in hospitalized neonates. Commonly used antihypertensive agents have resulted in significant adverse effects in neonatal and pediatric populations. Nicardipine is a desirable option because of its rapid and titratable antihypertensive properties and low incidence of adverse effects. However, data for use in neonatal ECMO are limited. We conducted a retrospective review of patients less than 44 weeks post-menstrual age who received a nicardipine infusion for first-line treatment of systemic hypertension while on ECMO at our institution between 2010 and 2016. Systolic (SBP), diastolic (DBP), and mean arterial (MAP) blood pressures were evaluated for 48-h after nicardipine initiation. Eight neonates received a nicardipine infusion while on ECMO during the study period. Nicardipine was initiated at a mean dose of 0.52 ( ± 0.22) mcg/kg/min and titrated to a maximum dose of 1.1 ( ± 0.85) mcg/kg/min. The median duration of nicardipine use was 51 (range 4-227) hours. Significant decreases in SBP, DBP, and MAP occurred within one hour of initiation of nicardipine and were sustained through the majority of the 48-h evaluation period. No patients experienced hypotension. Prospective studies are warranted to evaluate the optimal dose, safety, and efficacy of nicardipine in neonates who require ECMO.

Nicardipine for Hypertension Following Aortic Coarctectomy or Superior Cavopulmonary Anastomosis

BACKGROUND

Literature on the use of nicardipine, a dihydropyridine calcium channel antagonist, in children recovering from cardiac surgery is sparse and, to our knowledge, nonexistent in children with single ventricle anatomy. We aimed to report our experience with nicardipine in these patient populations.

METHODS

We performed a retrospective review of children recovering from aortic coarctectomy or superior cavopulmonary anastomoses who received nicardipine for hypertension at our institution between 2007 and 2013. Hemodynamic variables prior to and after nicardipine initiation were compared using paired t tests.

RESULTS

Seven children recovering from aortic coarctectomy (median age 8.6 months, range: 1.5 months-7.9 years) and four children recovering from superior cavopulmonary anastomosis (median age: seven months, range: five-nine months) were reviewed. For all patients, at six hours after initiation of nicardipine, mean systolic blood pressure was significantly decreased, 123 ± 19 versus 103 ± 14 mm Hg (P = .001), as were diastolic blood pressure, 68 ± 20 versus 53.5 ± 10 mm Hg (P = .041), and sodium nitroprusside dose, 4.3 ± 2.9 versus 1.3 ± 1.7 mcg/kg/min (P = .002). Further, within 24 hours, serum lactate decreased from 1.45 ± 0.82 to 0.81 ± 0.29 mg/dL (P = .016). Heart rate, blood urea nitrogen, and serum creatinine measurements were statistically unchanged.

CONCLUSIONS

Nicardipine effectively decreased blood pressure without apparent adverse events in a small cohort of children with postoperative hypertension while recovering from aortic coarctectomy or superior cavopulmonary anastomosis. Further research comparing nicardipine to more conventional titratable antihypertensive agents in these patient populations is warranted.

Use of Continuous Infusion Hydralazine in a Pediatric Patient on Mechanical Circulatory Support

Hydralazine is a direct peripheral arterial vasodilator used for acute hypertension. Usually administered as a bolus dose, continuous infusion has been described during pregnancy for preeclampsia and eclampsia and in limited reports in cardiac surgeries for afterload reduction. This case describes the use of continuous infusion hydralazine for afterload reduction in an infant receiving extracorporeal membrane oxygenation (ECMO) post-cardiac surgery. Postsurgery, the patient's mean arterial pressures (MAPs) could not be controlled despite escalating doses of vasodilatory medications including nitroprusside, nicardipine, and milrinone; hence, continuous infusion hydralazine was initiated. Although the initiation of a hydralazine infusion produced a decrease in MAP, the response was unsustainable. This case highlights an alternative method for managing systemic vascular resistance and cardiac output to allow for myocardial recovery after cardiac surgery and use of extracorporeal support. At the time of this writing, this is the first published case describing hydralazine administration via continuous infusion in pediatric patients. The use of continuous infusion hydralazine for afterload reduction provided a brief, non-sustained reduction in MAP in a post-cardiac surgery infant managed on ECMO support.

Thiocyanate Accumulation in Critically Ill Patients Receiving Nitroprusside Infusions

PURPOSE

This study evaluated thiocyanate concentrations and factors associated with thiocyanate accumulation in intensive care unit patients receiving nitroprusside with and without sodium thiosulfate coadministration.

MATERIALS AND METHODS

This retrospective study evaluated critically ill adults who received nitroprusside infusions and had at least one thiocyanate concentration. Patients with thiocyanate accumulation (concentrations ≥30 µg/mL) were compared to patients without accumulation. Factors associated with accumulation were determined by Spearman correlation and multivariate regression.

RESULTS

Thiocyanate concentrations (n = 192) were obtained from 87 patients. Fourteen of the 87 (16%) patients experienced thiocyanate accumulation with a mean (SD) thiocyanate concentration of 44 ± 11 µg/mL. Patients with accumulation had received greater cumulative nitroprusside doses (28 vs 8.2 mg/kg, P < .01), greater cumulative sodium thiosulfate doses (16.8 vs 10.1 mg/kg, P < .01), and longer infusion durations (10.9 vs 6.0 days, P < .01), compared to patients without accumulation. Sodium thiosulfate coadministration resulted in greater thiocyanate concentrations (22.8 ± 16.7 vs 16.8 ± 14.9 μg/mL, P = .01), despite utilization of lower cumulative nitroprusside doses (10.2 vs 14.6 mg/kg, P = .03). Cumulative nitroprusside dose ( r² .44, P < .001) and cumulative sodium thiosulfate dose ( r² .32, P < .001) demonstrated a significant correlation with measured thiocyanate concentrations. Thiocyanate accumulation was independently associated with cumulative nitroprusside dose in mg/kg (regression coefficient 0.75, 95% CI 0.63-0.89; P < .01). No clinically significant adverse effects of cyanide or thiocyanate toxicity were observed.

CONCLUSIONS

Cumulative nitroprusside dose was independently associated with thiocyanate accumulation. Despite elevated thiocyanate levels in 16% of patients, there was no clinical evidence of cyanide or thiocyanate toxicity. Routine monitoring of thiocyanate concentrations appears most warranted in patients receiving higher cumulative doses of nitroprusside.

Inhaled therapy for the management of perioperative pulmonary hypertension

Patients with pulmonary hypertension (PH) are at high risk for complications in the perioperative setting and often receive vasodilators to control elevated pulmonary artery pressure (PAP). Administration of vasodilators via inhalation is an effective strategy for reducing PAP while avoiding systemic side effects, chiefly hypotension. The prototypical inhaled pulmonary-specific vasodilator, nitric oxide (NO), has a proven track record but is expensive and cumbersome to implement. Alternatives to NO, including prostanoids (such as epoprostenol, iloprost, and treprostinil), NO-donating drugs (sodium nitroprusside, nitroglycerin, and nitrite), and phosphodiesterase inhibitors (milrinone, sildenafil) may be given via inhalation for the purpose of treating elevated PAP. This review will focus on the perioperative therapy of PH using inhaled vasodilators.

Effects of sodium nitroprusside on mouse erythrocyte catalase activity and malondialdehyde status

There is controversy about the anti- or pro-oxidative effects of the nitric oxide (NO)-donor sodium nitroprusside (SNP). Hence, the activity of the antioxidant enzyme catalase (CAT) and the status of malondialdehyde (MDA) were investigated after a 2.5 mg/kg dose of SNP had been i.p. administered to different and comparable groups of mice (n = 48). The drug was administered at two different circadian times (1 and 13 h after light onset [HALO]). There were, irrespectively of sampling time, no significant differences in the means of CAT activity and MDA status between control and SNP-treated groups, no matter the treatment time. However, CAT activity was significantly (Student's t-test, p < 0.001) increased 1 h following SNP administration at 1 HALO, whereas the significant (p < 0.001) increase in the enzyme activity was found only 3 h after injection at 13 HALO. The drug dosing either at 1 or 13 HALO resulted in no significant differences of MDA status between control and treated groups regardless to the sampling time. Two-way analysis of variance (ANOVA) detected a significant (F0.05(7,88)= 5.3; p < 0.0006) interaction between sampling time and treatment in mice injected at 1 HALO, suggesting the influence of treatment on sampling-time-related changes in CAT activity. However, ANOVA validated no interaction between the two factors in mice treated at 13 HALO, illustrating that the sampling-time differences in enzyme activity were greater. Furthermore, two-way ANOVA revealed no interaction in the variation of MDA status in animals treated either at 1 or 13 HALO. This study indicates that SNP significantly affected the anti-oxidant system.

Safety and efficacy of sodium nitroprusside during prolonged infusion in pediatric patients

OBJECTIVE

Sodium nitroprusside is a direct-acting vasodilator used to lower blood pressure in the operating room and ICU. The efficacy of sodium nitroprusside has been analyzed in few pediatric randomized trials. This study assesses the efficacy and safety of sodium nitroprusside following at least 12 hours of IV infusion in children.

DESIGN

Randomized, double-blind withdrawal to placebo study.

SETTING

ICUs.

PATIENTS

Pediatric patients younger than 17 years.

INTERVENTIONS

Following 12-24 hours of open-label sodium nitroprusside titration, a blinded infusion of sodium nitroprusside or placebo was administered (at the stable rate used at the end of the open-label phase) for up to 30 minutes.

MEASUREMENTS AND MAIN RESULTS

The primary efficacy measure was whether control of mean arterial blood pressure was lost, that is, increased above ambient baseline for two consecutive minutes during the blinded phase. The proportion of patients who lost mean arterial blood pressure control in the placebo group (15/19; 79%) was significantly different than those in the sodium nitroprusside group (9/20; 45%) (p = 0.048). Three patients experienced rebound hypertension during the blinded phase, and all were in the placebo group. Serious adverse event rates were low (7/52; 13%), and in only one patient was the serious adverse event determined to be related to sodium nitroprusside by the site investigator. Fourteen patients (27%) had whole blood cyanide levels above 0.5 μg/mL, with high correlation (0.7) between infusion rate and cyanide levels, but there were few clinical signs of cyanide toxicity.

CONCLUSIONS

Sodium nitroprusside is efficacious in maintaining mean arterial blood pressure control in children following a 12-hour infusion. Although a high proportion of patients were found to have elevated cyanide levels, toxicity was not observed.

Sodium nitroprusside in 2014: A clinical concepts review

Sodium nitroprusside has been used in clinical practice as an arterial and venous vasodilator for 40 years. This prodrug reacts with physiologic sulfhydryl groups to release nitric oxide, causing rapid vasodilation, and acutely lowering blood pressure. It is used clinically in cardiac surgery, hypertensive crises, heart failure, vascular surgery, pediatric surgery, and other acute hemodynamic applications. In some practices, newer agents have replaced nitroprusside, either because they are more effective or because they have a more favorable side-effect profile. However, valid and adequately-powered efficacy studies are sparse and do not identify a superior agent for all indications. The cyanide anion release concurrent with nitroprusside administration is associated with potential cyanide accumulation and severe toxicity. Agents to ameliorate the untoward effects of cyanide are limited by various problems in their practicality and effectiveness. A new orally bioavailable antidote is sodium sulfanegen, which shows promise in reversing this toxicity. The unique effectiveness of nitroprusside as a titratable agent capable of rapid blood pressure control will likely maintain its utilization in clinical practice for the foreseeable future. Additional research will refine and perhaps expand indications for nitroprusside, while parallel investigation continues to develop effective antidotes for cyanide poisoning.

Dosing-time dependent oxidative effects of sodium nitroprusside in brain, kidney, and liver of mice

The purpose of this study was to investigate if the oxidative effects of sodium nitroprusside (SNP) are dosing-time dependent. Therefore, the variation of malondialdehyde (MDA) status was assessed after a single i.p. administration of SNP (2.5mgkg(-1) b.w.) or vehicle (9‰ NaCl) to different and comparable groups of mice (n=48) at two different circadian times (1 and 13h after light onset [HALO]). Brain, kidney, and liver tissues were excised over 36h, and their MDA contents were estimated at 0, 1, 3, 6, 9, 12, 24, and 36h after SNP administration.

RESULTS

indicated mean MDA level was not significantly changed in each investigated tissue compared with the control. In contrast, the mean MDA value varied among organs and was comparable in brain and liver but lower than in kidney. The data show SNP significantly (P<0.05) increases MDA status in both tissues and exerts time-dependent oxidative effects with the greatest toxicity coinciding with the beginning of the diurnal rest span (local time: 08:00h, i.e., at 1 HALO). The obtained results reveal SNP-induced oxidative damage (evidenced by MDA accumulation) varies according to both the dosing-time and the target organ.

Pharmacotherapy of pediatric advanced life support and toxicological emergencies

Guidelines for pediatric advanced life support have been available for nearly a quarter of a century. Recommendations for the pharmacological management of pediatric cardiac arrest have changed over these years. Several important differences have been observed between adult advanced cardiac life support and pediatric advanced life support that must be recognized when children require resuscitation, such as the cause of the arrest, age-specific monitoring parameters, weight-based medication dosing, and obstacles in obtaining venous access. To make matters more complicated, differences also exist across neonatal and pediatric age spectrums. In addition, some toxicological emergencies commonly occurring in children require pharmacological management with agents that have a unique mechanism of action for cardiac support.

Clevidipine for perioperative blood pressure control in infants and children

Various pharmacologic agents have been used for perioperative BP control in pediatric patients, including sodium nitroprusside, nitroglycerin, β-adrenergic antagonists, fenoldopam, and calcium channel antagonists. Of the calcium antagonists, the majority of the clinical experience remains with the dihydropyridine nicardipine. Clevidipine is a short-acting, intravenous calcium channel antagonist of the dihydropyridine class. It undergoes rapid metabolism by non-specific blood and tissue esterases with a half-life of less than 1 minute. As a dihydropyridine, its cellular and end-organ effects parallel those of nicardipine. The clevidipine trials in the adult population have demonstrated efficacy in rapidly controlling BP in various clinical scenarios with a favorable adverse effect profile similar to nicardipine. Data from large clinical trials regarding the safety and efficacy of clevidipine in children is lacking. This manuscript aims to review the commonly used pharmacologic agents for perioperative BP control in children, discuss the role of calcium channel antagonists such as nicardipine, and outline the preliminary data regarding clevidipine in the pediatric population.

The interpretation of perioperative lactate abnormalities in patients undergoing cardiac surgery

Hyperlactataemia and lactic acidosis are commonly encountered during and after cardiac surgery. Perioperative lactate production increases in the myocardium, skeletal muscle, lungs and in the splanchnic circulation during cardiopulmonary bypass. Hyperlactataemia has a bimodal distribution in the perioperative period. An early increase in lactate levels, arising intraoperatively or soon after intensive care unit admission, is a familiar and concerning finding for most clinicians. It is highly suggestive of tissue ischaemia and is associated with a prolonged intensive care unit stay, a prolonged requirement for respiratory and cardiovascular support and increased postoperative mortality. Its presence should prompt a thorough search for potential causes of tissue hypoxia. In contrast, late-onset hyperlactataemia, a less well recognised complication, occurs 4 to 24 hours after completion of surgery and is typically associated with preserved cardiac output and oxygen delivery. Risk factors for late-onset hyperlactataemia include hyperglycaemia, long cardiopulmonary bypass time and elevated endogenous catecholamines. Although patients with this complication may have a longer duration of ventilation and intensive care unit length of stay than those with normolactataemia, an association with increased mortality has not been demonstrated. The discovery of late-onset hyperlactataemia should not delay the postoperative progress of an otherwise stable patient following cardiac surgery.

Drug treatment of hypertensive crisis in children

Hypertensive crisis is a relatively rare event and is associated with significant morbidity and mortality in adults and pediatric patients alike. Rapid, safe, and effective treatment is imperative to alleviate immediate presenting clinical symptoms, prevent devastating morbidity, preserve long-term quality of life, and prevent mortality. Many medications in the hypertensive crisis arsenal have been used for nearly half a century. Nearly all treatment options have been utilized in children for decades, yet reliable data and sound clinical literature remain elusive. Every agent considered to be a first-line, second-line, or adjunctive option has yet to be evaluated in a randomized controlled trial in pediatric patients. With a paucity of clinical data to form evidence-based decisions, the clinician must rely entirely on the extrapolation from adult data and small retrospective studies, case series, and case reports of medication use in pediatric patients. Although more research in the treatment of pediatric hypertensive crisis is desperately needed, current practice demands a sharp knowledge of the pediatric clinical literature and pharmacology in this area as an essential tool to consistently improve patient outcomes with respect to morbidity and mortality.

Perioperative care of a child with transposition of the great arteries

OPINION STATEMENT

Because a minority of patients with D-transposition of the great arteries are diagnosed in utero by ultrasound, most present after delivery with cyanosis. In the absence of apparent lung disease, cyanotic neonates suspected of having a cardiac lesion should be immediately transferred to an intensive care unit at a pediatric tertiary care center for monitoring, resuscitation, and to define the cardiac anatomy and physiology. A prostaglandin E-1 infusion is usually initiated to maintain ductal patency and promote intra-cardiac mixing. In the past, balloon atrial septostomy (BAS) was routinely performed to enlarge the atrial septal defect and improve intra-cardiac mixing while the infants awaited surgery. Recent literature has reported an increase risk of stroke in neonates who undergo BAS, although more recent studies refute this. Our current practice is to perform BAS in neonates who have both echocardiographic evidence of a restrictive atrial septum and hypoxia or instability that is unresponsive to other interventions. The occasional patient who does not respond to initial management may have elevated pulmonary vascular resistance and may stabilize with pulmonary vasodilators, such as inhaled nitric oxide. Rarely, a child does not respond to interventional and pharmacologic resuscitation and requires mechanical support pre-operatively with extracorporeal membrane oxygenation (ECMO). In our experience, ECMO has been a successful bridge to corrective surgery with excellent outcomes. After pre-operative stabilization, arterial switch procedure is typically performed in the first week of life with very favorable early results.

Successful treatment by exchange transfusion of a young infant with sodium nitroprusside poisoning

Although sodium nitroprusside (SNP) is often used in pediatric intensive care units, cyanide toxicity can occur after SNP treatment. To treat SNP-induced cyanide poisoning, antidotes such as amyl nitrite, sodium nitrite, sodium thiosulfate, and hydroxycobalamin should be administered immediately after diagnosis. Here, we report the first case of a very young infant whose SNP-induced cyanide poisoning was successfully treated by exchange transfusion. The success of this alternative method may be related to the fact that exchange transfusion not only removes the cyanide from the blood but also activates detoxification systems by supplying sulfur-rich plasma. Moreover, exchange transfusion replaces cyanide-contaminated erythrocytes with fresh erythrocytes, thereby improving the blood's oxygen carrying capacity more rapidly than antidote therapy. Therefore, we believe that exchange transfusion might be an effective therapeutic modality for critical cases of cyanide poisoning.

Sodium-nitroprusside-induced cyanide toxicity in pediatric patients

BACKGROUND

Sodium nitroprusside (SNP) is often used as a continuous infusion intravenous vasodilator in pediatric patients. However, cyanide toxicity can occur with SNP therapy. Scant literature is available determining the safety of SNP therapy, the incidence of cyanide toxicity or the risk factors for cyanide toxicity in pediatric patients.

OBJECTIVE

To review the literature concerning the safety of intravenous SNP with regard to cyanide toxicity in the pediatric patient population.

METHODS

A MedLine search was used to identify articles pertaining to SNP therapy and cyanide toxicity in pediatric patients.

CONCLUSIONS

Sodium nitroprusside seems to be safe when used in critically ill pediatric patients. Cyanide toxicity may occur in patients with specific risk factors. Routine monitoring of cyanide levels may not be warranted.