Pulmonary and systemic hemodynamic responses to ketamine in infants with normal and elevated pulmonary vascular resistance

Surgery and Anesthesia in Patients with Pulmonary Hypertension

Pulmonary hypertension is characterized by right ventricular impairment and a reduced ability to compensate for hemodynamic insults. Consequently, surgery can be challenging but is increasingly considered in view of available specific therapies and improved longer term survival. Optimal management requires a multidisciplinary patient-centered approach involving surgeons, anesthetists, pulmonary hypertension clinicians, and intensivists. The optimal pathway involves risk:benefit assessment for the proposed operation, optimization of pulmonary hypertension and any comorbidities, the appropriate anesthetic approach for the specific procedure and patient, and careful monitoring and management in the postoperative period. Where patients are carefully selected and meticulously managed, good outcomes can be achieved.

Perioperative approach to precapillary pulmonary hypertension in non-cardiac non-obstetric surgery

Pulmonary hypertension (PH) confers a significant challenge in perioperative care. It is associated with substantial morbidity and mortality. A considerable amount of information about management of patients with PH has emerged over the past decade. However, there is still a paucity of information to guide perioperative evaluation and management of these patients. Yet, a satisfactory outcome is feasible by focusing on elaborate disease-adapted anaesthetic management of this complex disease with a multidisciplinary approach. The cornerstone of the peri-anaesthetic management of patients with PH is preservation of right ventricular (RV) function with attention on maintaining RV preload, contractility and limiting increase in RV afterload at each stage of the patient's perioperative care. Pre-anaesthetic evaluation, choice of anaesthetic agents, proper fluid management, appropriate ventilation, correction of hypoxia, hypercarbia, acid-base balance and pain control are paramount in this regard. Essentially, the perioperative management of PH patients is intricate and multifaceted. Unfortunately, a comprehensive evidence-based guideline is lacking to navigate us through this complex process. We conducted a literature review on patients with PH with a focus on the perioperative evaluation and suggest management algorithms for these patients during non-cardiac, non-obstetric surgery.

Anesthetic Considerations in Pediatric Patients With Acute Decompensated Heart Failure

Acute decompensated heart failure (ADHF) in pediatrics is a significant cause for morbidity and mortality in children. Congenital heart disease and cardiomyopathy are the leading etiologies of ADHF. It is common for these children to undergo diagnostic, therapeutic, or surgical procedure under anesthesia, which may be associated with significant morbidity and mortality. The importance of preanesthetic multidisciplinary planning with all involved teams, including anesthesia, cardiology, intensive care, perfusion, and cardiac surgery, cannot be emphasized enough. In order to safely manage these patients, it is imperative for the anesthesiologist to understand the complex pathophysiological interactions between cardiopulmonary systems and anesthesia during these procedures. This review discusses the etiology, pathophysiology, clinical manifestations, and perioperative management of these patients.

The "Mother of pediatric cardiac anesthesia": An interview with Dr Dolly D. Hansen, a pioneering woman in medicine

Dr Dolly D. Hansen (1935-), Associate Professor in the Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children's Hospital and Harvard Medical School, devoted her life to improving the perioperative care of children with congenital heart disease. She applied her knowledge of cardiovascular and pulmonary physiology and the effects on anesthetic agents in children with and without heart disease into clinical practice and thereby greatly influenced the practice of pediatric anesthesia, cardiology, surgery, and critical care medicine. As an exceptional master clinician, leader, program builder, innovator, teacher, and academic role model, she shaped the careers of hundreds of fellows and young attendings, many of whom became leaders in the field.

Intrauterine growth restriction results in persistent vascular mismatch in adulthood

KEY POINTS

Intrauterine growth restriction (IUGR) increases offspring risk of chronic diseases later in life, including cardiovascular dysfunction. Our prior studies suggest biventricular cardiac dysfunction and vascular impairment in baboons who were IUGR at birth because of moderate maternal nutrient reduction. The current study reveals changes in artery sizes, distensibility, and blood flow pattern in young adult IUGR baboons, which may contribute to cardiac stress. The pattern of abnormality observed suggests that vascular redistribution seen with IUGR in fetal life may continue into adulthood.

ABSTRACT

Maternal nutrient reduction induces intrauterine growth restriction (IUGR), increasing risks of chronic diseases later in life, including cardiovascular dysfunction. Using ultrasound, we determined regional blood flow, blood vessel sizes, and distensibility in IUGR baboons (8 males, 8 females, 8.8 years, similar to 35 human years) and controls (12 males, 12 females, 9.5 years). The measured blood vessels were larger in size in the males compared to females before but not after normalization to body surface area. Smaller IUGR normalized blood vessel sizes were observed in the femoral and external iliac arteries but not the brachial or common carotid arteries and not correlated significantly with birth weight. Mild decrease in distensibility in the IUGR group was seen in the iliac but not the carotid arteries without between-sex differences. In IUGR baboons there was increased carotid arterial blood flow velocity during late systole and diastole. Overall, our findings support the conclusion that region specific vascular and haemodynamic changes occur with IUGR, which may contribute to the occurrence of later life cardiac dysfunction. The pattern of alteration observed suggests vascular redistribution efforts in response to challenges in the perinatal period may persist into adulthood. Further studies are needed to determine the life course progression of these changes.

Initial presentation and management of pediatric heart failure

PURPOSE OF REVIEW

Heart failure is a rare but morbid diagnosis in the pediatric patient presenting to the emergency department (ED). Familiarity of the ED physician with the presentation, work-up, and management of pediatric heart failure is essential as accurate diagnosis is reliant on a high degree of suspicion.

RECENT FINDINGS

Studies evaluating pediatric heart failure are limited by its rarity and the heterogeneity of underlying conditions. However, recent reports have provided new data on the epidemiology, presentation, and outcomes of children with heart failure.

SUMMARY

The recent studies reviewed here highlight the significant diagnostic and management challenges that pediatric heart failure presents given the variety and lack of specificity of its presenting signs, symptoms, and diagnostic work-up. This review provides the ED physician with a framework for understanding of pediatric heart failure to allow for efficient diagnosis and management of these patients. The primary focus of this review is heart failure in structurally normal hearts.

Perioperative events in children with pulmonary hypertension undergoing non-cardiac procedures

Prior limited research indicates that children with pulmonary hypertension (PH) have higher rates of adverse perioperative outcomes when undergoing non-cardiac procedures and cardiac catheterizations. We examined a single-center retrospective cohort of children with active or pharmacologically controlled PH who underwent cardiac catheterization or non-cardiac surgery during 2006–2014. Preoperative characteristics and perioperative courses were examined to determine relationships between the severity or etiology of PH, type of procedure, and occurrence of major and minor events. We identified 77 patients who underwent 148 procedures at a median age of six months. The most common PH etiologies were bronchopulmonary dysplasia (46.7%), congenital heart disease (29.9%), and congenital diaphragmatic hernia (14.3%). Cardiac catheterizations (39.2%), and abdominal (29.1%) and central venous access (8.9%) were the most common procedures. Major events included failed planned extubation (5.6%), postoperative cardiac arrest (4.7%), induction or intraoperative cardiac arrest (2%), and postoperative death (1.4%). Major events were more frequent in patients with severe baseline PH (P = 0.006) and the incidence was associated with procedure type (P = 0.05). Preoperative inhaled nitric oxide and prostacyclin analog therapies were associated with decreased incidence of minor events (odds ratio [OR] = 0.32, P = 0.046 and OR = 0.24, P = 0.008, respectively), but no change in the incidence of major events. PH etiology was not associated with events (P = 0.24). Children with PH have increased risk of perioperative complications; cardiac arrest and death occur more frequently in patients with severe PH and those undergoing thoracic procedures. Risk may be modified by using preoperative pulmonary vasodilator therapy and lends itself to further prospective studies.

Landmark papers in pediatric cardiac anesthesia: documenting the history of the specialty

Pediatric cardiac anesthesia has developed over the past eight decades into a specialty delivering complex clinical care and contributing remarkable scientific progress. The history of this development can be traced through journal articles that mark the strides of the specialty. This article discusses journal articles, chosen by the author, that he considers had a significant impact on the practice of pediatric cardiac anesthesia or are of historical interest.

How Does One Safely Anesthetize a Univentricular Patient for Noncardiac Surgery?

As the surgical, perioperative, and pediatric management of univentricular patients advances, more anesthesiologists will see these challenging patients as children, teenagers, and adults come to the operating room for common noncar diac surgeries: tonsillectomy, appendectomy, labor and de livery, etc. The univentricular heart has 2 atrioventricular valves with 1 ventricular chamber or a large dominant ven tricle associated with a diminutive opposing ventricle. The common pathway of physiology is complete mixing of blood. Blood pressure and oxygen saturation are dependent on the ratio of pulmonary vascular resistance (PVR) to sys temic vascular resistance (SVR). A thorough history and physical examination give the anesthesiologist insight into what further laboratory evaluations and interventions are needed. The 3 key issues with respect to echocardiographic evaluation of the heart are ventricular function, atrioventric ular valve insufficiency, and pulmonary artery stenosis or distortion. After completion of the ventricular bypass proce dures, the hemodynamics rely on the homeostasis of the PVR/SVR ratio, ventricular performance, and oxygen deliv ery. Therefore, the univentricular physiology is best served by spontaneous ventilation. Intraoperative and postopera tive pain management is key to facilitating extubation of the patient's trachea and subsequently expediting recovery from surgery.

Sedation and Analgesia in Pediatric Cardiac Critical Care

OBJECTIVES

This review will focus on the pharmacokinetics (with an emphasis on the context-sensitive half-time), pharmacodynamics, and hemodynamic characteristics of the most commonly used sedative/hypnotic, analgesic, and IV anesthetics used in cardiac intensive care. In addition, the assessment of pain and agitation and withdrawal will be reviewed.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSIONS

Children in the cardiac ICU often require one or more components of general anesthesia: analgesia, amnesia (sedation and hypnosis), and muscle relaxation to facilitate mechanical ventilation, to manage postoperative pain, to perform necessary procedures, and to alleviate fear and anxiety. Furthermore, these same children are often vulnerable to hemodynamic instability due to unique underlying physiologic vulnerabilities. An assessment of hemodynamic goals, postoperative procedures to be performed, physiologic vulnerabilities, and the intended duration of mechanical ventilation should be made. Based on this assessment, the optimal selection of sedatives, analgesics, and if necessary, muscle relaxants can then be made.

Hemodynamic response to ketamine in children with pulmonary hypertension

BACKGROUND

The safety of ketamine in children with pulmonary hypertension has been debated because of conflicting results of prior studies in which changes in mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) have been widely variable. The goal of this prospective study was to quantitate the effects of ketamine on pulmonary hemodynamics in a cohort of children with pulmonary hypertension under conditions in which variables such as airway/ventilatory management, FiO(2), and use of vasodilating anesthetics were controlled.

METHODS

The IRB approved this study of 34 children undergoing cardiac catheterization for pulmonary hypertension studies. Following anesthetic induction with sevoflurane and tracheal intubation facilitated by the administration of rocuronium 0.7-1 mg·kg(-1) iv, sevoflurane was discontinued and anesthesia was maintained with midazolam 0.1 mg·kg(-1) iv (or 0.5 mg·kg(-1) po preoperatively) and remifentanil iv infusion 0.5-0.7 mcg·kg(-1) ·min(-1). Ventilation was mechanically controlled to maintain PaCO(2) 35-40 mmHg. When endtidal sevoflurane was 0% and FiO(2) was 0.21, baseline heart rate (HR), mean arterial pressure (MAP), mPAP, right atrial pressure (RAP), pulmonary artery occlusion pressure (PAOP), right ventricular end-diastolic pressure (RVEDP), cardiac output, and arterial blood gases were measured, and indexed systemic vascular resistance (SVRI), indexed pulmonary vascular resistance (PVRI), and cardiac index (CI) were calculated. Each child then received a bolus of ketamine 2 mg·kg(-1) infused over 2 min. Measurements and calculations were repeated 2 min after the conclusion of the infusion.

RESULTS

The mean (95% CI) increase in mPAP following ketamine was 2 mmHg (0.2, 3.7), which was statistically significant but clinically insignificant. PVRI and PVRI/SVRI did not change significantly. Hemodynamic changes did not differ among subjects with differing severity of pulmonary hypertension or between subjects chronically treated with pulmonary vasodilators or not.

CONCLUSION

Ketamine is associated with minimal, clinically insignificant hemodynamic changes in sedated, mechanically ventilated children with pulmonary hypertension.

Perioperative care of infants with pyloric stenosis

Pyloric stenosis (PS) is one of the most common surgical conditions affecting neonates and young infants. The definitive treatment for PS is surgical pyloromyotomy, either open or laparoscopic. However, surgical intervention should never be considered urgent or emergent. More importantly, emergent medical intervention may be required to correct intravascular volume depletion and electrolyte disturbances. Given advancements in surgical and perioperative care, morbidity and mortality from PS should be limited. However, either may occur related to poor preoperative resuscitation, anesthetic management difficulties, or postoperative complications. The following manuscript reviews the current evidence-based medicine regarding the perioperative care of infants with PS with focus on the preoperative assessment and correction of metabolic abnormalities, intraoperative care including airway management (particularly debate related to rapid sequence intubation), maintenance anesthetic techniques, and techniques for postoperative pain management. Additionally, reports of applications of regional anesthesia for either postoperative pain control or as an alternative to general anesthesia are discussed. Management recommendations are provided whenever possible.

Anesthetic Drugs in Congenital Heart Disease

The structural defects associated with the various forms of congenital heart disease lead to pathological and functional changes that place patients at risk for adverse events, and in fact the perioperative incidence of morbidity and mortality has been documented to be increased in children with congenital heart disease. Patients with congenital heart disease can present to the anesthesiologist in a relatively precarious state of balance of several hemodynamic factors, including preload, ventricular contractility, systemic vascular resistance, pulmonary vascular resistance, heart rate, and cardiac rhythm. Anesthetic drugs can affect each of these, and an ideal anesthetic drug for such patients does not exist. The purpose of this article is to review the hemodynamic effects of anesthetic drugs and how they may contribute to the occurrence of adverse events in children with congenital heart disease.

The anesthetic management of children with pulmonary hypertension in the cardiac catheterization laboratory

Children need cardiac catheterization to establish the diagnosis and monitor the response to treatment when undergoing drug therapy for the treatment of pulmonary arterial hypertension (PAH). Children with PAH receiving general anesthesia for cardiac catheterization procedures are at significantly increased risk of perioperative complications in comparison with other children. The most acute life-threatening complication is a pulmonary hypertensive crisis. It is essential that the anesthesiologist caring for these children understands the pathophysiology of the disease, how anesthetic medications may affect the patient's hemodynamics, and how to manage an acute pulmonary hypertensive crisis.

Use of ketamine during procedural sedation: indications, controversies, and side effects

Ketamine is a well-described anesthetic and analgesic, unique in its ability to preserve laryngeal reflexes and airway protection, and offered to a wide range of patients, although not necessarily widely used. Because it is considered an anesthetic, widespread use by all sedation providers is often limited despite its long history as a safe sedative. Because of its sympathomimetic effects, ketamine may be used in patients who are hypovolemic, including those who are experiencing traumatic or obstetric emergencies. The use of ketamine in patients with epilepsy or traumatic brain injury is more controversial. This article will explore the side effects of ketamine and current research that support or discourage its use in a variety of settings.

Perioperative anesthesiological management of patients with pulmonary hypertension

Pulmonary hypertension is a major reason for elevated perioperative morbidity and mortality, even in noncardiac surgical procedures. Patients should be thoroughly prepared for the intervention and allowed plenty of time for consideration. All specialty units involved in treatment should play a role in these preparations. After selecting each of the suitable individual anesthetic and surgical procedures, intraoperative management should focus on avoiding all circumstances that could contribute to exacerbating pulmonary hypertension (hypoxemia, hypercapnia, acidosis, hypothermia, hypervolemia, and insufficient anesthesia and analgesia). Due to possible induction of hypotonic blood circulation, intravenous vasodilators (milrinone, dobutamine, prostacyclin, Na-nitroprusside, and nitroglycerine) should be administered with the greatest care. A method of treating elevations in pulmonary pressure with selective pulmonary vasodilation by inhalation should be available intraoperatively (iloprost, nitrogen monoxide, prostacyclin, and milrinone) in addition to invasive hemodynamic monitoring. During the postoperative phase, patients must be monitored continuously and receive sufficient analgesic therapy over an adequate period of time. All in all, perioperative management of patients with pulmonary hypertension presents an interdisciplinary challenge that requires the adequate involvement of anesthetists, surgeons, pulmonologists, and cardiologists alike.

Anesthetic considerations for nontransplant procedures in lung transplant patients

Lung transplantation has become an accepted option for many patients with end-stage pulmonary diseases. Anesthesia and surgery following lung transplantation may be required for various diseases that may affect both systemic organs and the transplanted graft. When a patient with a lung transplant undergoes surgery, there is the potential for interference with lung function, depending on the type of intervention and its anatomical site. Accurate preoperative evaluation, an understanding of the physiology of the transplanted lung, proper airway instrumentation, individualized management of intraoperative ventilation, and fluid balance are essential for a positive perioperative outcome.

The comparison of the effect of three anesthetic induction regimens on the arterial oxygen saturation in children with tetralogy of fallot undergoing cardiac surgery

BACKGROUND

Tetralogy of fallot (TOF) is the most common cyanotic congenital heart disease. Anesthesia induction is a challenging issue in these patients due to the risk of worsening hypoxemia following decrease in pulmonary blood flow. We evaluated the effect of three anesthetic induction regimens on the arterial oxygen saturation (SaO2%) in children with TOF.

METHODS

Seventy six children aged 50 days to 15 years old with TOF, scheduled in Nemazee and Faghihi hospitals to undergo elective cardiac surgery during 1385-1388 were randomly divided into 3 groups to receive three anesthetic induction agents including ketamine (2 mg/kg, IV), ketamine (5 mg/kg, IM) and halothane for gas induction. SaO2% and heart rate were recorded before induction and thereafter every 1 minute during induction of anesthesia till 10 min post-induction.

RESULTS

There were not significant differences between three groups regarding pattern of changes in SaO2% during 10 min post-induction. All three groups showed an increase in SaO2% committed over 6th minute but this pattern was not seen after that time. In addition, there were not significant differences among groups according to heart rate in the study period.

CONCLUSION

It seems that anesthesia induction in TOF patients with ketamine IV and IM and halothane did not have significant adverse effects on SaO2%. Indeed, oxygenation during induction may offset other possible adverse effects of induction drugs on SaO2%.

Ketamine-etomidate for children undergoing cardiac catheterization

The purpose of this study was to determine the effects of combined low-dose ketamine and etomidate on hemodynamics during cardiac catheterization in children with congenital cardiac shunts. Sixty children undergoing routine diagnostic cardiac catheterization were included: 30 had a right-to-left shunt, and 30 had a left-to-right shunt. Both groups were given a single dose of etomidate 0.3 mg·kg(-1) with ketamine 1 mg·kg(-1). There were no hemodynamic changes in the group with a right-to-left shunt. In cases of left-to-right shunt, there were significant differences in heart rate, right atrial pressure, mean arterial pressure, mean pulmonary artery pressure, pulmonary artery wedge pressure, and systemic vascular resistance index. Decreases in pulmonary blood flow and pulmonary-systemic shunt ratio were also observed. Further studies are required with dose titration of this anesthetic combination in pediatric patients with congenital heart disease involving a left-to-right shunt.

Impaired lung function after intubation and mechanical ventilation for surgical ligation of the ductus arteriosus in preterm infants

OBJECTIVE

Significant patent ductus arteriosus (PDA) in the preterm infant has been associated with pulmonary edema and impaired gas exchange. Therefore, surgical ligature of the DA may be required. However, the effects of intubation and mechanical ventilation on the PDA-induced lung dysfunction presently are unknown. The aim of the study was to investigate whether intubation and mechanical ventilation alter pulmonary function in the preterm infant with significant PDA.

DESIGN

A prospective study.

SETTING

The neonatal intensive care unit and department of anesthesiology in a university hospital.

PARTICIPANTS

Preterm infants <32 weeks' gestational age treated with nasal continuous positive airway pressure (NCPAP) and requiring mechanical ventilation for undergoing surgical DA ligature.

INTERVENTIONS

Respiratory, Doppler echocardiographic parameters, and chest x-ray transparencies of the lungs were measured during NCPAP and 2 hours after intubation and starting mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

Twenty preterm infants (gestational age = 27 ± 1 wk, birth weight = 950 ± 140 g) were included. Heart rate, O(2) need, PaCO(2), and plasma lactate concentrations were significantly higher after intubation. The mean oxygenation index increased from 1.5 ± 0.6 to 7.2 ± 3 (p < 0.05). The overall transparencies of the lungs decreased after intubation. DA diameter, shortening fraction of the left ventricle, left pulmonary artery blood flow velocities, and left atrium/aorta did not change.

CONCLUSION

In preterm infants with significant PDA, intubation and mechanical ventilation before surgical DA ligation may increase the O(2) need and PaCO(2) and may promote lung edema formation. Mechanical ventilation-induced impairment in lung function is not associated with a change in pulmonary or systemic circulation or DA flow. Special care should be taken to prevent respiratory failure when intubation and mechanical ventilation are required for undergoing surgical DA ligation in the preterm infant.

General anesthesia for children with severe heart failure

Severe heart failure in children is uncommon. The anesthetic management of children with this condition is challenging. The authors aimed to identify the frequency with which anesthesia for short noncardiac surgical procedures or investigations was complicated by life-threatening hemodynamic instability and to describe the anesthetic techniques used. This study retrospectively reviewed the anesthetic charts and notes of children admitted acutely with a diagnosis of severe heart failure (fractional shortening of 15% or less) who received general anesthesia for noncardiac surgical or diagnostic interventions during the 3-year period from September 2005 to September 2008. In this study, 21 children received a total of 28 general anesthetics. Two patients (10%) experienced a cardiac arrest, and both required unplanned admission to the authors' pediatric intensive care unit (PICU) postoperatively. A variety of anesthetic techniques was used. In 27 (96%) of the 28 cases, perioperative inotropic support was required. General anesthesia for children with severe heart failure is associated with a significant complication rate and should be administered by anesthetists familiar with managing all aspects of circulatory support for children in an appropriate setting.

Anesthesia considerations for children with pulmonary hypertension

Children with pulmonary arterial hypertension undergoing anesthesia pose a challenge. The prevalence of morbidity and mortality in this subgroup is substantially greater than that in the general population. In this article, we attempt to describe the adverse events that occur and also identify some of the factors that may precipitate them. We also suggest mechanisms to attenuate or prevent these crises.

Dexmedetomidine/ketamine for diagnostic cardiac catheterization in a child with idiopathic pulmonary hypertension

The use of a combination of dexmedetomidine and ketamine to provide procedural sedation in a 12-year old boy with a diagnosis of idopathic pulmonary hypertension and a behavioral disorder, undergoing diagnostic cardiac catheterization, is presented. Following a loading dose of ketamine one mg/kg and dexmedetomidine one mcg/kg, an infusion of dexmedetomidine at one mcg/kg/hr was used with the patient breathing spontaneously. Stable hemodynamics were observed throughout the procedure and pulmonary vascular resistance was measured under three conditions. The dexmedetomidine infusion was continued for two hours post-catheterization, facilitating a smooth emergence.

Perioperative complications in children with pulmonary hypertension undergoing general anesthesia with ketamine

BACKGROUND

Pulmonary arterial hypertension (PAH) is associated with significant perioperative risk for major complications in children, including pulmonary hypertensive crisis and cardiac arrest. Uncertainty remains about the safety of ketamine anesthesia in this patient population.

AIM

Retrospectively review the medical records of children with PAH to ascertain the nature and frequency of peri-procedural complications and to determine whether ketamine administration was associated with peri-procedural complications.

METHODS

Children with PAH (mean pulmonary artery pressure > or =25 mmHg and pulmonary vascular resistance index > or =3 Wood units) who underwent general anesthesia for procedures during a 6-year period (2002-2008) were enrolled. Details about the patient, PAH, procedure, anesthetic and postprocedural course were noted, including adverse events during or within 48 h of the procedure. Complication rates were reported per procedure. Association between ketamine and peri-procedural complications was tested.

RESULTS

Sixty-eight children (median age 7.3 year, median weight 22 kg) underwent 192 procedures. Severity of PAH was mild (23%), moderate (37%), and severe (40%). Procedures undertaken were major surgery (n = 20), minor surgery (n = 27), cardiac catheterization (n = 128) and nonsurgical procedures (n = 17). Ketamine was administered during 149 procedures. Twenty minor and nine major complications were noted. Incidence of cardiac arrest was 0.78% for cardiac catheterization procedures, 10% for major surgical procedures and 1.6% for all procedures. There was no procedure-related mortality. Ketamine administration was not associated with increased complications.

CONCLUSIONS

Ketamine appears to be a safe anesthetic option for children with PAH. We report rates for cardiopulmonary resuscitation and mortality that are more favorable than those previously reported.

Anaesthesia and right ventricular failure

Acute right ventricular (RV) failure has until recently received relatively little attention in the cardiology, critical care or anaesthesia literature. However, it is frequently encountered in cardiac surgical cases and is a significant cause of mortality in patients with severe pulmonary hypertension who undergo non-cardiac surgery. RV dysfunction may be primarily due to impaired RV contractility, or volume or pressure overload. In these patients, an increased pulmonary vascular resistance (PVR) or a decreased aortic root pressure may lead to RV ischaemia, resulting in a rapid, downward haemodynamic spiral. The key aspects of 'RV protection' in patients who are at risk of perioperative decompensation are prevention, detection and treatment aimed at reversing the underlying pathophysiology. Minimising PVR and maintaining systemic blood pressure are of central importance in the prevention of RV decompensation, which is characterised by a rising central venous pressure and a falling cardiac output. Although there are no outcome data to support any therapeutic strategy for RV failure when PVR is elevated, the combination of inhaled iloprost or intravenous milrinone with oral sildenafil produces a synergistic reduction in PVR, while sparing systemic vascular resistance. Levosimendan is a promising new inotrope for the treatment of RV failure, although its role in comparison to older agents such as dobutamine, adrenaline and milrinone has yet to be determined. This is also the case for the use of vasopressin as an alternative pressor to noradrenaline. If all else has failed, mechanical support of the RV should be considered in selected cases.

Anesthetic management of children with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is associated with significant perioperative risk for major complications, including pulmonary hypertensive crisis and cardiac arrest. Several mechanisms of hemodynamic deterioration, including acute increases in pulmonary vascular resistance (PVR), alterations of ventricular contractility and function and coronary hypoperfusion can contribute to morbidity. Anesthetic drugs exert a variety of effects on PVR, some of which are beneficial and some undesirable. The goals of balanced and cautious anesthetic management are to provide adequate anesthesia and analgesia for the surgical procedure while minimizing increases in PVR and depression of myocardial function. The development of specific pulmonary vasodilators has led to significant advances in medical therapy of PAH that can be incorporated in anesthetic management. It is important that anesthesiologists caring for children with PAH be aware of the increased risk, understand the pathophysiology of PAH, form an appropriate anesthetic management plan and be prepared to treat a pulmonary hypertensive crisis.

Ketamine does not increase pulmonary vascular resistance in children with pulmonary hypertension undergoing sevoflurane anesthesia and spontaneous ventilation

BACKGROUND

The use of ketamine in children with increased pulmonary vascular resistance is controversial. In this prospective, open label study, we evaluated the hemodynamic responses to ketamine in children with pulmonary hypertension (mean pulmonary artery pressure >25 mm Hg).

METHODS

Children aged 3 mo to 18 yr with pulmonary hypertension, who were scheduled for cardiac catheterization with general anesthesia, were studied. Patients were anesthetized with sevoflurane (1 minimum alveolar anesthetic concentration [MAC]) in air while breathing spontaneously via a facemask. After baseline catheterization measurements, sevoflurane was reduced (0.5 MAC) and ketamine (2 mg/kg IV over 5 min) was administered, followed by a ketamine infusion (10 microg x kg(-1) x min(-1)). Catheterization measurements were repeated at 5, 10, and 15 min after completion of ketamine load. Data at various time points were compared (ANOVA, P < 0.05).

RESULTS

Fifteen patients (age 147, 108 mo; median, interquartile range) were studied. Diagnoses included idiopathic pulmonary arterial hypertension (5), congenital heart disease (9), and diaphragmatic hernia (1). At baseline, median (interquartile range) baseline pulmonary vascular resistance index was 11.3 (8.2) Wood units; 33% of patients had suprasystemic mean pulmonary artery pressures. Heart rate (99, 94 bpm; P = 0.016) and Pao2 (95, 104 mm Hg; P = 007) changed after ketamine administration (baseline, 15 min after ketamine; P value). There were no significant differences in mean systemic arterial blood pressure, mean pulmonary artery pressure, systemic or pulmonary vascular resistance index, cardiac index, arterial pH, or Paco2.

CONCLUSIONS

In the presence of sevoflurane, ketamine did not increase pulmonary vascular resistance in spontaneously breathing children with severe pulmonary hypertension.

Pharmacological therapy for analgesia and sedation in the newborn

Rapid advances have been made in the use of pharmacological analgesia and sedation for newborns requiring neonatal intensive care. Practical considerations for the use of systemic analgesics (opioids, non-steroidal anti-inflammatory agents, other drugs), local and topical anaesthetics, and sedative or anaesthetic agents (benzodiazepines, barbiturates, other drugs) are summarised using an evidence-based medicine approach, while avoiding mention of the underlying basic physiology or pharmacology. These developments have inspired more humane approaches to neonatal intensive care. Despite these advances, little is known about the clinical effectiveness, immediate toxicity, effects on special patient populations, or long-term effects after neonatal exposure to analgesics or sedatives. The desired or adverse effects of drug combinations, interactions with non-pharmacological interventions or use for specific conditions also remain unknown. Despite the huge gaps in our knowledge, preliminary evidence for the use of neonatal analgesia and sedation is available, but must be combined with a clear definition of clinical goals, continuous physiological monitoring, evaluation of side effects or tolerance, and consideration of long-term clinical outcomes.

Anesthesia and analgesia during and after surgery in neonates

BACKGROUND

Historically, the use of anesthetics and analgesics in neonates and infants has been based on extrapolations from studies performed in adults and older children. Over the past 20 years, there has been a growing body of research on the clinical pharmacology and clinical outcomes of these agents in neonates and infants.

OBJECTIVE

This article summarizes clinical pharmacology and clinical outcomes studies of opioids, opioid antagonists, sedative-hypnotics, nonsteroidal anti-inflammatory drugs and acetaminophen, and local anesthetics in neonates and infants to highlight gaps in the available knowledge, review some concerns about study design, and identify drugs that should receive high priority for future study.

METHODS

Relevant studies were identified through a search of MEDLINE and a review of textbooks, conference proceedings, and abstracts. The available literature was subjected to expert committee-based review.

CONCLUSIONS

There is a growing body of information on analgesic and anesthetic pharmacokinetics, pharmacodynamics, and clinical outcomes in neonates and infants, permitting safe and effective use in some clinical settings. Major gaps in knowledge persist, however. Future research may involve a combination of clinical trials and preclinical studies in suitable infant animal surrogate models.

Anesthetic Care During Modified Fontan Procedure Without Cardiopulmonary Bypass

OBJECTIVE

The purpose of this study was to report the anesthetic care of patients during performance of a Fontan procedure without cardiopulmonary bypass (CPB).

DESIGN

Retrospective chart review.

SETTING

Operating room of a university hospital.

PARTICIPANTS

Seven pediatric-patients undergoing inferior vena cava (IVC)-to-pulmonary artery (PA) anastomosis for completion of the Fontan procedure.

INTERVENTIONS

Charts were reviewed for anesthetic technique, hemodynamic and ventilatory changes occurring during the procedure, and anesthetic interventions that were provided.

MEASUREMENTS AND MAIN RESULTS

The off-bypass Fontan procedure was attempted in 7 patients (age: 26 months-7 years, weight: 13 to 28 kg). Exposure of the PA was not feasible in 1 patient because of a markedly enlarged right atrium. In the remaining 6 patients, before cross-clamping of the PA to allow for the proximal anastomosis between the PA and the conduit, alkalosis (pH > or =7.5) was maintained by the administration of sodium bicarbonate. After PA cross-clamping, fluid administration was necessary in 5 patients and dopamine (3-7 microg/kg/min) was necessary in 4 patients. The minute ventilation was increased by 18 +/- 7% to maintain baseline PaCO2 values. Before the placement of the PA cross-clamp, the end-tidal PaCO2 difference was 7 +/- 4 mmHg and the transcutaneous (TC)-PaCO2 difference was 3 +/- 2 mmHg. The end-tidal PaCO2 difference increased to 14 +/- 6 mmHg during cross-clamping of the PA, whereas no change was noted in the TC-PaCO2 difference. Once the proximal anastomosis was completed, a bridge was placed to redirect blood from the IVC to the right atrium while the IVC was clamped and attached to the distal end of the conduit. After placement of the distal end of the bridge into the IVC, fluid administration to maintain the blood pressure was necessary in 3 patients. In 1 patient, 20 minutes after placement of the bridge, the authors noted a progressive increase in the central venous pressure reading measured from the left femoral vein and the need for the administration of volume to maintain the mean arterial pressure. Examination of the bridge revealed occlusion with thrombus despite an activated coagulation time value of 250 to 300 seconds. The tracheas of 3 of the 6 patients were extubated in the operating room, whereas the other 3 were extubated in the pediatric intensive care unit within 4 hours of completion of the procedure. The 1 patient who required the use of CPB required reintubation and had a protracted intensive care unit course. The other 6 patients were discharged home on postoperative days 7 to 12.

CONCLUSIONS

With alteration of the anesthetic technique, the Fontan procedure can be performed in selected patients without the need for CPB.

Analgesia and anesthesia for neonates: Study design and ethical issues

OBJECTIVE

The purpose of this article is to summarize the clinical, methodologic, and ethical considerations for researchers interested in designing future trials in neonatal analgesia and anesthesia, hopefully stimulating additional research in this field.

METHODS

The MEDLINE, PubMed, EMBASE, and Cochrane register databases were searched using subject headings related to infant, newborn, neonate, analgesia, anesthesia, ethics, and study design. Cross-references and personal files were searched manually. Studies reporting original data or review articles related to these topics were assessed and critically evaluated by experts for each topical area. Data on population demographics, study characteristics, and cognitive and behavioral outcomes were abstracted and synthesized in a systematic manner and refined by group members. Data synthesis and results were reviewed by a panel of independent experts and presented to a wider audience including clinicians, scientists, regulatory personnel, and industry representatives at the Newborn Drug Development Initiative workshop. Recommendations were revised after extensive discussions at the workshop and between committee members.

RESULTS

Designing clinical trials to investigate novel or currently available approaches for analgesia and anesthesia in neonates requires consideration of salient study designs and ethical issues. Conditions requiring treatment include pain/stress resulting from invasive procedures, surgical operations, inflammatory conditions, and routine neonatal intensive care. Study design considerations must define the inclusion and exclusion criteria, a rationale for stratification, the confounding effects of comorbid conditions, and other clinical factors. Significant ethical issues include the constraints of studying neonates, obtaining informed consent, making risk-benefit assessments, defining compensation or rewards for participation, safety considerations, the use of placebo controls, and the variability among institutional review boards in interpreting federal guidelines on human research. For optimal study design, investigators must formulate well-defined study questions, choose appropriate trial designs, estimate drug efficacy, calculate sample size, determine the duration of the studies, identify pharmacokinetic and pharmacodynamic parameters, and avoid drug-drug interactions. Specific outcome measures may include scoring on pain assessment scales, various biomarkers and their patterns of response, process outcomes (eg, length of stay, time to extubation), intermediate or long-term outcomes, and safety parameters.

CONCLUSIONS

Much more research is needed in this field to formulate a scientifically sound, evidence-based, and clinically useful framework for management of anesthesia and analgesia in neonates. Newer study designs and additional ethical dilemmas may be defined with accumulating data in this field.

Which anesthetic agent alters the hemodynamic status during pediatric catheterization? comparison of propofol versus ketamine

OBJECTIVE

To compare the effects of propofol and ketamine on systemic and pulmonary circulations in pediatric patients scheduled for elective cardiac catheterization.

DESIGN

Prospective, randomized, and blinded.

SETTING

University hospital.

PARTICIPANTS

Children (n = 41) undergoing cardiac catheterization.

INTERVENTIONS

All children were premedicated with oral midazolam 60 minutes before the procedure. Patients were separated into 3 groups according to shunts diagnosed by transthoracic echocardiography before the catheterization procedure: patients without cardiac shunt (Group I, n = 11), left-to-right shunt (Group II, n = 12), and right-to-left shunt (Group III, n = 18). A continuous infusion of propofol (100-200 microg/kg/min) or ketamine (50-75 microg/kg/min) was randomly started in all groups to obtain immobility during the procedure. Hemodynamic data, including systemic venous, pulmonary artery and vein, aortic saturations and pressures, were recorded; Qp/Qs were calculated. The same set of data was recorded before discontinuation of infusions at the end of the procedure.

MEASUREMENTS AND MAIN RESULTS

After the propofol administration, in all 3 patient groups propofol infusion was associated with significant decreases in systemic mean arterial pressure. In groups with cardiac shunts (Group II and III), propofol infusion significantly decreased systemic vascular resistance and increased systemic blood flow, whereas pulmonary vascular resistance and pulmonary blood flow did not change significantly. These changes resulted in decreased left-to-right shunting and increased right-to-left shunting; the pulmonary-to-systemic flow ratio decreased significantly. On the other hand, after ketamine infusion, systemic mean arterial pressure increased significantly in all patient groups, but pulmonary mean arterial pressure, systemic vascular resistance, and pulmonary vascular resistance were unchanged.

CONCLUSION

In children with cardiac shunting, the principal hemodynamic effect of propofol is a decrease in systemic vascular resistance. In children with intracardiac shunting, this results in an increase in right-to-left shunting and a decrease in the ratio of pulmonary to systemic blood flow, which may lead to arterial desaturation. Ketamine did not produce these changes. The authors suggested that during cardiac catheterization in children, both the anesthesiologists and cardiologists need to know that anesthetic agents can significantly alter the hemodynamic status in children with complex congenital heart defects and affect the results of hemodynamic calculations that are important for decision-making and treatment of these patients.

Care of children who have had surgery for congenital heart disease

Children who have had surgical correction for congenital heart disease can present to the ED with an acute illness that could be associated with their cardiac lesion. There is no data available to summarize complications that could be associated with surgically corrected congenital heart disease. This work was undertaken to describe the common procedures used, list known complications of these procedures, and review general management principles in caring for the acutely ill child who has had heart surgery.

Adverse effects of sedatives in children

The application of sedation/analgesia in paediatric patients is rapidly expanding as less invasive, non-operative techniques of diagnosis and treatment are applied to the paediatric population. Medical providers who are asked to provide sedation may include radiologists, paediatricians, nurses and emergency physicians, as well as anaesthesiologists and intensive care physicians. At the same time, the range of drugs used in these settings has expanded considerably. As there is no single drug fulfilling the criteria for the ideal sedative (rapid-onset, rapid recovery, no adverse effects, immobility appropriate to procedure being performed), multiple drugs may be used in combination. It is imperative that practitioners using drugs for sedation/analgesia in children be aware of the adverse effect profile(s) of these drugs, both individually and in combination. The purpose of this review is to describe the adverse effects of sedative and reversal agents currently used in paediatric sedation/analgesia.

Repeated administration of ketamine may lead to neuronal degeneration in the developing rat brain

BACKGROUND

This study was conducted to investigate, in vivo, the dose and duration effects of ketamine administration on neuronal degeneration in the developing rat brain.

METHODS

Seven-day-old (P7) Sprague-Dawley rats were treated with intraperitoneal injections of ketamine, a noncompetitive N-methyl-D-aspartate receptor antagonist. Degenerating neurones were identified by the cupric-silver stain from 10 brain regions using the stereological disector method.

RESULTS

A single dose of ketamine (25, 50 and 75 mg.kg-1) did not increase neuronal degeneration compared with the saline-treated control. However, repeated doses of ketamine (25 mg.kg-1) at 90-min intervals over 9 h increased degenerating neurones in seven out of 10 brain regions.

CONCLUSIONS

These findings suggest that the duration of ketamine exposure correlates with increased neuronal degeneration in the developing rat brain.

Severe pulmonary hypertension in a patient with bronchiectasis complicated by cor pulmonale and a right-to-left shunt presenting for surgery

A patient with advanced bronchiectasis, severe pulmonary hypertension complicated by cor pulmonale and a right-to-left shunt at atrial level presented for sigmoid colectomy. We outline the potential perioperative problems of this situation, discuss the perioperative risks and describe our clinical approach. A total intravenous anaesthetic technique using midazolam, fentanyl, ketamine and rocuronium was used to minimize changes in pulmonary and systemic vascular resistance and not induce bronchospasm. Preoperative nebulized salbutamol and ipratroprium were given to prevent bronchospasm and adrenaline and noradrenaline were infused to maintain cardiac output and the balance between systemic and pulmonary vascular resistance.