Anesthesia for children with pericardial effusion: a case series

Objectives and aims: To review the anesthetic management of children requiring surgical intervention for pericardial effusion, determine the nature and frequency of complications and define risk factors that predict perioperative risk. Background: Anesthesia in the presence of a pericardial effusion may be associated with significant hemodynamic compromise particularly during induction. However, the literature specifically concerning children is limited to a single‐case report. Methods: A retrospective case review of children undergoing general anesthesia for surgical treatment for pericardial effusion between 1999 and 2008 at a single institution. Results: Sixty‐five children underwent 79 general anesthetics for surgical treatment for pericardial effusion. Median age was 4 years (2 weeks–16 years), and median weight 15 kg (range, 2.5–96 kg). Fifty‐five children (84%) developed effusions following cardiac surgery. The commonest induction agent was ketamine (25/65, 38%), and the majority of children (52/65, 80%) were intubated and ventilated for the procedure. Seven children (11%) suffered from eight major complications, and 14 children (22%) suffered from a minor complication. Major complications were more common in children with preoperative tachypnoea (P = 0.01) and cardiac tamponade on preoperative echocardiogram (ECHO) (P = 0.001). Preoperative hypoxia had a sensitivity of 92% and a positive likelihood ratio of 5.2 (95% CI 1.5–17.5) for predicting all complications. Conclusions: Anesthesia for pericardial effusion in children was associated with an adverse physiological event in one‐third of children. Major complications may be predicted by preoperative tachypnoea and cardiac tamponade on preoperative ECHO, and all complications may be predicted by preoperative hypoxia. The anesthetic technique included a variety of induction agents, and we cannot recommend a particular approach.     

Experience of percutaneous coronary intervention in the management of pediatric cardiac allograft vasculopathy.

In a retrospective study, we examined the procedural success rate and the short-, intermediate-, and long-term outcomes of coronary interventional procedures in children with cardiac allograft vasculopathy. Seven patients underwent 13 interventional procedures: balloon angioplasty alone (n = 3), angioplasty with stenting (n = 9), or angioplasty with brachytherapy (n = 1), with procedural success in all. Two major complications (cardiac arrest) and a single death occurred in the immediate postprocedural period. Five (83%) of the remaining 6 patients developed moderate to severe restenosis, diffuse disease, or progressive vasculopathy; 3 have been retransplanted, 1 died from progressive cardiac allograft vasculopathy, and 1 is awaiting retransplantation, 40 months after the procedure.     

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.     

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.     

Anesthesia for noncardiac procedures for children with a Berlin Heart EXCOR® Pediatric Ventricular Assist Device: a case series

Objectives: To report our experience of providing anesthesia for noncardiac procedures in children with in situ Berlin Heart EXCOR Pediatric^® ventricular assist devices and to suggest principles of anesthetic management. Background: With the initiation of the first North American training and support center for Berlin Heart at our institution in 2006, we have been asked to provide anesthesia for noncardiac procedures to these children. No current anesthetic approach to these children has been reported. Methods/Materials: Anesthetic records for all noncardiac procedures for children with Berlin Heart between August 2006 and February 2009 in a tertiary care pediatric hospital were retrospectively reviewed. Charts were reviewed for demographic and clinical data, perioperative management, and occurrence of hypotension. Results: Twenty‐nine procedures were performed on 11 patients. Hypotension was a common occurrence with all anesthetic induction and maintenance agents even at low doses. Ketamine induction, however, was less likely to produce hypotension, odds ratio for hypotension 0.1333 (95% confidence range 0.021–0.856). Hypotension was responsive to fluid bolus (60%) and alpha‐receptor agonists (100%). Preoperative stability and presence of biventricular ventricular assist device (BiVAD) did not predict intraoperative hemodynamic course. Conclusions: Unlike patients with other ventricular assist devices, these children do not tolerate reductions in systemic vascular resistance (SVR) because of the relatively fixed cardiac output of this device. Agents that reduce SVR should be avoided where possible. Preoperative stability is not predictive. Fluids and alpha‐agonists should be first‐line response to hypotension in this population. Further study of this unusual population is warranted to further delineate best anesthetic practice.     

Anesthetic implications of ornithine transcarbamylase deficiency

Background: Ornithine transcarbamylase deficiency (OTCD) is an X‐linked urea cycle disorder associated with potentially fatal episodes of hyperammonemia. Children with OTCD often require anesthesia. There is insufficient information regarding perioperative complications and optimal management of anesthesia in these patients. Aim: To retrospectively review the medical records of children with OTCD to ascertain the nature and frequency of peri‐procedural complications. Methods/Materials: The electronic medical records of Mayo Clinic patients with OTCD who underwent anesthesia between the dates of January 2003 and September 2009 were reviewed. Results: Nine patients with OTCD underwent 25 anesthetics using a variety of anesthetic techniques, including four major surgeries. Eleven procedures were performed prior to OTCD diagnosis and those patients were not receiving therapy for a urea cycle disorder. In the other cases, patients were on a variety of therapies for OTCD. Fourteen patients were outpatient procedures. Clinical signs of postoperative metabolic decompensation did not occur. Conclusions: In this series, patients with OTCD tolerated anesthesia well. Choice of perioperative management of OTCD and the choice of anesthetic technique should be individualized and based on clinical circumstances, but should have the underlying aim of minimizing protein catabolism. It appears patients with stable OTCD may undergo minor procedures as outpatients safely.     

The addition of ketamine to a morphine nurse‐ or patient‐controlled analgesia infusion (PCA/NCA) increases analgesic efficacy in children with mucositis pain

Aim: To assess the efficacy of adding ketamine to morphine nurse‐ or patient‐controlled analgesia (NCA/PCA) infusions in treating mucositis pain in children. Background: Mucositis pain can be very difficult to control in some patients despite the use of parenteral opioids. In our institution, we have started adding low‐dose ketamine to the morphine NCA/PCA in these children in an effort to improve analgesic efficacy. Methods/materials: The records of all children receiving a morphine/ketamine PCA or NCA for mucositis pain in our institution from 1999 to 2007 were reviewed. At the time of treatment, details of the analgesic management and consumption, pain scores and side effects were prospectively recorded and then entered on to an electronic database. Ketamine was added at a concentration of 20 or 40 μg·kg^?1 per ml with our standard morphine NCA/PCA infusions and protocols being used. Results: In 28 patients, there was no difference between average morphine consumption in the 24 h pre and post the addition of ketamine (33.1 (±10.7) vs 35.2 (±14.3) μg·kg^?1 per hour, P = 0.45) but in those with recorded pain scores (n = 16), the median percentage of pain scores ≥4 was 48% (13–100%) preketamine versus 33% (0–82%) postketamine (P = 0.01). In all patients, there was no change in the rates of nausea and vomiting and pruritis pre and post the addition of ketamine and no other significant side effects were reported. No difference was seen between those who had 20 or 40 μg·kg^?1 per ml of ketamine added. Conclusion: The addition of ketamine to a morphine NCA/PCA improves analgesic efficacy in children with mucositis pain with no increase in the incidence of side effects.     

Pretreatment with intravenous ketamine reduces propofol injection pain

BACKGROUND: Paediatric procedural sedation using propofol has been shown to be safe and effective and is widely used. Pain at the injection site is a frequent complaint and can be particularly distressing for children, especially for those undergoing repeated procedures. Ketamine has analgesic properties and can diminish the incidence of propofol infusion pain in adults. The aim of the study was to investigate whether pretreatment with ketamine would reduce infusion line pain in propofol sedation in children. METHODS: We performed a prospective, randomized, double-blind trial in a paediatric sedation unit of a tertiary referral teaching hospital. A total of 122 children admitted for gastroscopy were randomly allocated into two groups. Group 1 received atropine and ketamine before propofol infusion. Group 2 received atropine, normal saline solution, and a mixture of propofol with lidocaine. The main outcome measure evaluated was pain associated with the infusion and secondary outcome measures were mean medium arterial pressure decrease and desaturation. RESULTS: The incidence of pain of the infusion was significantly lower in patients pretreated with ketamine (8% vs 37%, P = 0.0001). CONCLUSIONS: Pretreatment with ketamine (0.5 mg.kg-1) is very effective in preventing propofol infusion pain.     

Exploring the pharmacokinetics of oral ketamine in children undergoing burns procedures

Aims: The aim of this study was to describe ketamine pharmacokinetics when administered orally to children suffering from burn injury in >10% body surface area. Methods: Children (n = 20) were given ketamine 5 or 10 mg·kg^?1 orally 20 min prior to presentation for surgical procedures. Anesthesia during procedures was maintained with a volatile anesthetic agent. Additional intravenous ketamine was given as a bolus (0.5–1 mg·kg^?1) to nine children during the procedure while a further nine children were given an infusion (0.1 mg·kg^?1·h^?1) continued for 4–19 h after the procedure. Blood was assayed for ketamine and norketamine on six occasions over the study duration of 8–24 h. Data were pooled with those from an earlier analysis (621 observations from 70 subjects). An additional time–concentration profile from an adult given oral ketamine was gleaned from the literature (17 observations). A population analysis was undertaken using nonlinear mixed‐effects models. Results: The pooled analysis comprised 852 observations from 91 subjects. There were 20 children who presented for procedures related to burns management (age 3.5 sd 2.1 years, range 1–8 years; weight 14.7 sd 4.9 kg, range 7.9–25 kg), and these children contributed 214 ketamine and norketamine observations. A two‐compartment (central, peripheral) linear disposition model fitted data better than a one‐compartment model. Bioavailability of the oral formulation was 0.45 (90% CI 0.33, 0.58). Absorption half‐time was 59 (90% CI 29.4, 109.2) min and had high between‐subject variability (BSV 148%). Population parameter estimates, standardized to a 70‐kg person, were central volume 21.1 (BSV 47.1%) l·70 kg^?1, peripheral volume of distribution 109 (27.5%) l·70 kg^?1, clearance 81.3 (46.1%) l·h^?1·70 kg^?1, and inter‐compartment clearance 259 (50.1%) l·h^?1·70 kg^?1. Under the assumption that all ketamine was converted to norketamine, the volume of the metabolite was 151.9 (BSV 39.1%) l·70 kg^?1 with an elimination clearance of 64.4 (BSV 63.4%) l·h^?1·70 kg^?1 and a rate constant for intermediate compartments of 26.2 (BSV 52.1%) h^?1·70 kg^?1. Conclusions: The ketamine pharmacokinetics in children with minor burns are similar to those without burns. The peak ratio of norketamine/ketamine at 1 h is 2.8 after oral administration allowing an analgesic contribution from the metabolite at this time. There is low relative bioavailability (<0.5) and slow variable absorption. Dose simulation in a child (3.5 years, 15 kg) suggests a dose regimen of oral ketamine 10 mg·kg^?1 followed by intravenous ketamine 1 mg·kg^?1 i.v. with the advent of short‐duration surgical dressing change at 45 min.     

Pre-hospital use of ketamine in paediatric trauma

Objectives: To describe the use of ketamine in children by a pre-hospital physician-based service.
Methods: A five and a half year retrospective database review of all patients aged <16 years who were attended by London's Helicopter Emergency Medical Service and given ketamine.
Results: One hundred and sixty-four children met the inclusion criteria. The median age was 10 years (range 0–15 years). One hundred and four (63%) had a Glasgow Coma Scale (GCS) of 15 and 153 (93%) had a GCS>8 before administration of ketamine. Patients received from 2 to 150 mg ketamine IV (mean=1.0 mg/kg) and 112 (68%) received concomitant midazolam (0.5–18 mg, mean=0.1 mg/kg). One hundred and forty-one (86%) received ketamine intravenously and 23 (14%) intramuscularly. Only 12 patients (7%) were trapped. The most common mechanisms of injury in those who received ketamine were road traffic collisions, burns and falls.
Conclusion: The safe delivery of adequate analgesia and appropriate sedation is a priority in paediatric pre-hospital care. Ketamine was predominantly used in awake non-trapped patients with blunt trauma for procedural sedation and analgesia. Detailed database searches did not demonstrate loss of airway, oxygen desaturation or clinically significant emergence reactions after ketamine administration. This study failed to demonstrate any major side effects of the drug and reassured us that the safety profile of the drug in this environment is likely to be satisfactory. The use of ketamine in trapped children was rare.     

Comparison of propofol-fentanyl with propofol-fentanyl-ketamine combination in pediatric patients undergoing interventional radiology procedures

Background: With an increase in the frequency of interventional radiology procedures in pediatrics, there has been a corresponding increase in demand for procedural sedation to facilitate them . The purpose of our study was to compare the frequency of adverse effects, sedation level, patient recovery characteristics in pediatric patients receiving intravenous propofol fentanyl combination with or without ketamine for interventional radiology procedures. Our main hypothesis was that the addition of ketamine would decrease propofol/fentanyl associated desaturation. Methods and materials: Sixty consenting American Society of Anesthesia physical status I–III pediatric patients undergoing interventional radiology procedures under sedation were studied according to a randomized, double‐blinded, institutional review board approved protocol. Group 1 received propofol 0.5 mg·kg^?1 + fentanyl 1 μg·kg^?1 + ketamine 0.5 mg·kg^?1, and group 2 received propofol 0.5 mg·kg^?1 + fentanyl 1 μg·kg^?1 + same volume of %0.9 NaCl intravenously. Results: While apnea was not observed in any of the groups, there were three cases (10%) in group 1, and nine cases (30%) in group 2 with oxygen desaturation (P = 0.052). In group 1, 12 (40%) patients and, in group 2, 21 (70%) patients required supplemental propofol during the procedure (P = 0.021). There was no evidence for difference between groups in terms of other side effects except nystagmus. Conclusions: In conclusion, addition of low dose ketamine to propofol‐fentanyl combination decreased the risk of desaturation and it also decreased the need for supplemental propofol dosage in pediatric patients at interventional radiology procedures.     

Ketamine blockade of voltage-gated sodium channels: evidence for a shared receptor site with local anesthetics.

BACKGROUND: The general anesthetic ketamine is known to be an N-methyl-D-aspartate receptor blocker. Although ketamine also blocks voltage-gated sodium channels in a local anesthetic-like fashion, little information exists on the molecular pharmacology of this interaction. We measured the effects of ketamine on sodium channels. METHODS: Wild-type and mutant (F1579A) recombinant rat skeletal muscle sodium channels were expressed in Xenopus oocytes. The F1579A amino acid substitution site is part of the intrapore local anesthetic receptor. The effect of ketamine was measured in oocytes expressing wild-type or mutant sodium channels using two-electrode voltage clamp. RESULTS: Ketamine blocked sodium channels in a local anesthetic-like fashion, exhibiting tonic blockade (concentration for half-maximal inhibition [IC50] = 0.8 mm), phasic blockade (IC50 = 2.3 mm), and leftward shift of the steady-state inactivation; the parameters of these actions were strongly modified by alteration of the intrapore local anesthetic binding site (IC50 = 2.1 mm and IC50 = 10.3 mm for tonic and phasic blockade, respectively). Compared with lidocaine, ketamine showed greater tonic inhibition but less phasic blockade. CONCLUSIONS: Ketamine interacts with sodium channels in a local anesthetic-like fashion, including sharing a binding site with commonly used clinical local anesthetics.     

Case series: anesthesia for retrograde percutaneous aortic valve replacement — experience with the first 40 patients

Purpose: To describe both the evolution and the main associated complications in the anesthetic management of the initial 40 patients at our centre who underwent percutaneous retrograde aortic valve replacement, a novel technique utilizing a catheterguided femoral artery approach. Clinical features: With institutional Research Ethics Board approval, we retrospectively reviewed the medical records of the first 40 patients who underwent percutaneous retrograde aortic valve replacement between January 2005 and March 2006. Information obtained included patient characteristics, anesthetic management, details of the procedure, and complications. All procedures were scheduled to be performed in the cardiac catheterization laboratory. The first four patients received monitored anesthesia care, and the subsequent 36 underwent general anesthesia. There were no anesthesia-related adverse events. The prosthetic valve was placed successfully in 33/40 patients (83%). Median anesthetic time was 3.5 hr (range, 1.25–7.25 hr). Thirty-two/40 patients required vasopressor support. The most common, serious procedural complications were myocardial ischemia and arrhythmia following rapid ventricular pacing, hemorrhage from vascular injury secondary to the placement and removal of the large-bore sheath in the ilio-femoral artery, aortic rupture, and prosthetic valve maldeployment; 30-day mortality was 13% (n=5/40). Conclusions: Percutaneous retrograde aortic valve replacement is a novel procedure that presents the anesthesiologist with unique challenges. Careful preoperative assessment, intraoperative monitoring appropriate for a major vascular procedure, and meticulous management of hemodynamics are imperative for a successful outcome. Serious complications, including major hemorrhage from vascular injury as well as arrhythmia and myocardial ischemia following rapid ventricular pacing, must be anticipated and managed in an expeditious fashion.     

Incidents and complications during pediatric cardiac catheterization

BACKGROUND: Cardiac catheterization has revolutionized the management of pediatric cardiac disease. There has been little information on adverse events during these cases from an anesthesia viewpoint. The aim of this audit was to determine the incident rate during pediatric cardiac catheterization as contemporaneously reported by the anesthetist and to identify both the types of events and which procedures had the highest risk. METHODS: Since 1993, data have been collected prospectively on an audit form for every anesthetic given in our institution, and in-theatre events were recorded on this form. We have reviewed the data collected on pediatric cardiac catheterizations over a period of 9 years. RESULTS: A total of 4454 cardiac catheterizations were recorded. The overall incidence of events was 9.3%. Cardiac catheterization with occlusion of a patent ductus arteriosus (PDA) or a secundum atrial septal defect (ASD) had the lowest event rate at 4.2%. The figure for cardiac catheterization with other therapeutic interventions was 11.6 and 9.3% for solely diagnostic cardiac catheterization. The event rate in infants under the age of 1 year was 13.9% compared with 6.7% for those children over the age of 1 year. Of the 253 reports from cardiac catheterizations that could be analyzed further, there were 91 major complications including four deaths, 72 minor complications and 90 other incidents. CONCLUSIONS: Adverse events occur more commonly during cardiac catheterization than during pediatric anesthesia in general. Cases with highest risk are those in the under 1 year olds and those including a therapeutic intervention other than PDA or ASD occlusion.     

Endovascular Repair of Nontraumatic Ruptured Thoracic Aortic Pathologies

Endovascular repair of ruptured infrarenal abdominal aortic aneurysms (AAA) is receiving increased attention as the number of experienced users increases. Development of thoracic aortic stent grafts has lagged behind infrarenal advancements because of the reported prevalence of disease. In a few centers, however, the experience in performing thoracic stent graft procedures is quite substantial, such that endovascular therapy has been applied to ruptured thoracic aortic pathologies even though data remain limited and this novel therapy remains controversial. We report our combined experience with endovascular repair of ruptured thoracic aneurysms (RTA) and ruptured thoracic dissections (RTD). One hundred eighty-four thoracic stent graft procedures at the University of North Carolina (UNC) and Union Memorial Hospital (UMH) were reviewed and those patients undergoing RTA or RTD repair from January 1, 2000 to December 31, 2003 identified. Patients having procedures for elective repair or aortic transections were excluded from the analysis. Patient presentation, preoperative condition, procedural variables, mortality, and morbidity were examined. Seventy-four percent of the collective procedures were undertaken in high-risk patients (UNC, 38 of 40; UMH, 99 of 144). Twenty-two patients (8.7%; UNC, n = 6; UMH, n = 16) underwent treatment for either an RTA (n = 11) or an RTD (n = 11). The average age of this cohort was 66.5 ± 15.6 years and the average aneurysm diameter was 73.1 ± 31.4 mm. The mean duration of symptoms prior to repair was 103.1 ± 122 hr, influenced primarily by transport times and device availability. Stent graft exclusion was accomplished in 100% of patients with a procedural mortality of 0%. Commercial Talent devices were used in 19 patients (86.4%) and AneuRx device was used in 1 patient (4.5%). In the remaining two (9.1%) patients handmade devices constructed of Gianturco stents and Dacron fabric were used because of active hemorrhage and lack of appropriate device sizes. Operative time was 135.5 ± 48.5 min and was associated with an average blood loss of 242.0 ± 232.4 cc. Thirty-day mortality was 45.5% (RTA, 27.3%; RTD, 63.6%; p = 0.099). Length of stay in the intensive care unit was 6.1 ± 7.9 days and the mean hospital stay was 11.7 ± 10.6 days. Major complications were present in 54.5% of RTA (cardiac, 1; pulmonary, 3; cardiovascular accident, 2; spinal cord ischemia, 2; pulmonary embolism, 1), and 81.2% of RTD (multisystem organ failure, 7; pulmonary, 1; common femoral artery injury, 1) but not statistically different between groups. There were only two late complications (cardiac death, endoleak-Ia, 1) that occurred during the mean follow-up of 12.5 ± 11.3 (range, 1-32) months. These results indicate that endovascular repair of ruptured thoracic pathologies can be accomplished with an acceptable morbidity and mortality. There were no immediate procedural mortalities and complete exclusion was accomplished in all patients. Most postoperative complications arose from preexisting medical conditions and were not procedure related. The benefit of endovascular repair of ruptured thoracic aortic pathologies is promising.Presented at the Twenty-ninth Annual Meeting of the Peripheral Vascular Society, Anaheim, CA, June 4–5, 2004.     

Intravenous ketamine sedation for painful oncology procedures

BACKGROUND: The aim of the study was to determine the efficacy and adverse effects of intravenous (i.v.) ketamine sedation administered by nonanesthetist physicians for painful procedures. METHODS: A single-agent, procedural sedation protocol using titrated doses of ketamine i.v. (maximum 2 mg.kg(-1)) was conducted in outpatient pediatric oncology patients undergoing lumbar puncture (LP), bone marrow biopsy/aspiration (BMBx/A) or combination (LP/BMBx/A) in a tertiary care setting. The efficacy of analgesia and sedation (ability to perform the procedure), procedure duration, recovery time and the occurrence of adverse events are described. RESULTS: Fifty-eight subjects of a median age of 5 years (1-13) and median weight of 20 kg (10.5-68) underwent 119 sedations. An LP was performed in 73% of cases, a BMBx/A in 13% and LP/BMBx/A in 13%. Efficacy was 100% and the mean dose of ketamine was 1.3 mg.kg(-1) (0.4). The mean duration of the procedure was 6.6 min (4.2) and the recovery time was 11 min (4-45). Two subjects (1.7%) had a hypoxemia (SpO2 of <94%). No major airway complications occurred. The prevalence of hypertension (systolic > 20% at 5 min) was 54%. The median pain visual analogue score (VAS) for an observer was 0 (range 0-3) and caregiver was 0 (range 0-4). The median VAS for satisfaction (observer) was 10 (range 7-10) and caregiver VAS was also 10 (range 5-10). At 24 h after discharge, the incidence of bad dreams was 3.3%; vomiting, 10.8%; and abnormal behavior, 4.2%. CONCLUSION: Ketamine i.v. up to 2 mg.kg(-1) is an effective sedative for oncology procedures using a defined protocol.     

Ketamine Blockade of Voltage-gated Sodium Channels: Evidence for a Shared Receptor Site with Local Anesthetics

Background : The general anesthetic ketamine is known to be an N-methyl-d-aspartate receptor blocker. Although ketamine also blocks voltage-gated sodium channels in a local anesthetic-like fashion, little information exists on the molecular pharmacology of this interaction. We measured the effects of ketamine on sodium channels.

Methods : Wild-type and mutant (F1579A) recombinant rat skeletal muscle sodium channels were expressed in Xenopus oocytes. The F1579A amino acid substitution site is part of the intrapore local anesthetic receptor. The effect of ketamine was measured in oocytes expressing wild-type or mutant sodium channels using two-electrode voltage clamp.

Results : Ketamine blocked sodium channels in a local anesthetic-like fashion, exhibiting tonic blockade (concentration for half-maximal inhibition [IC50] = 0.8 mm), phasic blockade (IC50 = 2.3 mm), and leftward shift of the steady-state inactivation; the parameters of these actions were strongly modified by alteration of the intrapore local anesthetic binding site (IC50 = 2.1 mm and IC50 = 10.3 mm for tonic and phasic blockade, respectively). Compared with lidocaine, ketamine showed greater tonic inhibition but less phasic blockade.     

Anesthesia can be safely provided for children in a high-field intraoperative magnetic resonance imaging environment

Objectives: To describe the challenges associated with providing safe anesthesia and perioperative care for children in a remote intraoperative magnetic resonance (iMR) operating room (OR) and to identify perioperative anesthesia outcomes, including adverse events related to the iMR environment. Background: Increasingly, children undergo neurosurgical procedures in a high‐field iMR OR. We describe a 10‐year experience of providing anesthesia for children in this environment with a mobile 1.5‐Tesla magnet. Methods: A 10‐year retrospective analysis was conducted of children who underwent neurosurgical procedures in a high‐field mobile iMR OR. Primary outcomes related to perioperative adverse events and recovery profiles. Results were expressed as mean ± sd or median (range), as appropriate. Results: One hundred and five procedures were performed on 98 children, aged 4 months–18 years, weighing 6–112 kg. The commonest two diagnostic categories were tumor (n = 52) and seizures (n = 27). Median anesthetic time was 439 (185–710) mins. There were no significant adverse events related to the iMR environment. The mean postanesthetic care unit admission temperature was 37 ± 0.9°C and the mean modified Aldrete Score at 30 mins was 7.2 ± 0.9. Two patients experienced seizures in the immediate postoperative period, readily controlled with propofol. There was one breach of MR safety protocol, and no adverse events related to patient transport. Conclusions: Anesthesia and perioperative care of children in an iMR setting were associated with a very low incidence of complications, despite the duration of the procedures involved. Such success depends upon a cohesive team‐based approach.     

Ketamine attenuates post-operative cognitive dysfunction after cardiac surgery

Background: Post-operative cognitive dysfunction (POCD) commonly occurs after cardiac surgery. Ketamine exerts neuroprotective effects after cerebral ischemia by anti-excitotoxic and anti-inflammatory mechanisms. We hypothesized that ketamine attenuates POCD in patients undergoing cardiac surgery concomitant with an anti-inflammatory effect.
Methods: Patients randomly received placebo (0.9% saline; n =26) or an i.v. bolus of ketamine (0.5 mg/kg; n =26) during anesthetic induction. Anesthesia was maintained with isoflurane and fentanyl. A nonsurgical group ( n =26) was also included as control. Recent verbal and nonverbal memory and executive functions were assessed before and 1 week after surgery or a 1-week waiting period for the nonsurgical controls. Serum C-reactive protein (CRP) concentrations were determined before surgery and on the first post-operative day.
Results: Baseline neurocognitive and depression scores were similar in the placebo, ketamine, and nonsurgical control groups. Cognitive performance after surgery decreased by at least 2  SDs ( z -score of 1.96) in 21 patients in the placebo group and only in seven patients in the ketamine group compared with the nonsurgical controls ( P <0.001, Fisher's exact test). Cognitive performance was also significantly different between the placebo- and the ketamine-treated groups based on all z -scores ( P <0.001, Mann–Whitney U -test). Pre-operative CRP concentrations were similar ( P <0.33, Mann–Whitney U -test) in the placebo- and ketamine-treated groups. The post-operative CRP concentration was significantly ( P <0.01, Mann–Whitney U -test) lower in the ketamine-treated than in the placebo-treated group.
Conclusions: Ketamine attenuates POCD 1 week after cardiac surgery and this effect may be related to the anti-inflammatory action of the drug.     

A cohort evaluation of the Laryngeal Mask Airway‐Supreme™ in children

Objectives: To assess the clinical performance of the laryngeal mask airway‐Supreme in children. Aim: The purpose of this prospective audit was to evaluate the feasibility of the laryngeal mask airway‐Supreme in clinical practice and generate data for future comparison trials. Background: The laryngeal mask airway‐Supreme is a new second‐generation supraglottic airway that was recently released in limited pediatric sizes (sizes 1, 2). Methods: One hundred children, ASA I‐III, newborn to 16 years of age, and undergoing various procedures requiring a size 1, 2, or 3 laryngeal mask airway‐Supreme were studied. Assessments included insertion success rates, airway leak pressures, success of gastric tube insertion, quality of airway, and perioperative complications. Results: The first‐time insertion success rate was 97%, with an overall insertion success rate of 100%. The mean initial airway leak pressure for all patients was 22.3 ± 6.6 cm H₂O. Gastric tube placement was possible in 98% of patients. Complications were noted in six patients: coughing or laryngospasm (n = 3), sore throat (n = 1), and dysphonia (n = 2). Conclusions: The laryngeal mask airway‐Supreme was inserted with a high degree of success on the first attempt by clinicians with limited prior experience with the device. It was effectively used for a variety of procedures in children undergoing spontaneous and mechanical ventilation with minimal complications. The leak pressures demonstrated in this study, along with access for gastric decompression, suggest that the laryngeal mask airway‐Supreme may be an effective device for positive pressure ventilation in children.