Relationship between decrement time and recovery time in pediatric total intravenous anesthesia with propofol and remifentanil.

BACKGROUND: Propofol target-controlled infusion is now used in many countries for the administration of total intravenous anesthesia (TIVA) and uses population pharmacokinetic data incorporated into the target-controlled infusion pump to administer a dose which will achieve a target concentration selected by the practitioner. Modern target-controlled infusion pumps can include an estimate of how long it will take for the plasma propofol concentration to fall to a value programmed into the pump, once the propofol infusion is stopped. This is known as decrement time. Many users consider decrement time to be equivalent to recovery time for the patient, despite the several assumptions that makes. AIM: To determine if the decrement time estimated by the target-controlled infusion pumps at the end of anesthesia could be reliably used to predict recovery time for individual patients. METHODS: Target-controlled infusion pumps at Birmingham Children's Hospital are programmed with a propofol decrement concentration of 1.5 µg.mL-1 . Patients for a variety of surgical procedures were anesthetised with propofol-remifentanil TIVA. Eye opening was used as a surrogate of recovery time. Data were analyzed using median absolute deviation, Mann-Whitney U test, and linear regression to see if there was any correlation with decrement time and recovery time, total dose of propofol administered, duration of anesthesia and patient age. RESULTS: A total of 55 patients were audited. Median age was 7.2 years (range 0.9-15.9), and median weight was 26 kg (range 8.5-77). Median decrement time was 11.8 min (IQR 8.3-21), while median recovery time was 15 min (IQR 9-20). Recovery time was the same as decrement time in 2% of patients, less than in 40% of patients and more in 58% of patients. Two thirds of patients opened eyes at an estimated plasma propofol concentration between 1.2 and 1.8 µg.mL-1 . The median absolute deviation for the difference between decrement time and recovery time was 5.7 min, from a median of 1 min. Analysis demonstrated there was no statistical correlation between decrement time to 1.5 µg.mL-1 and recovery time, age, total propofol dose administered, or duration of anesthesia, for individual patients. CONCLUSION: There was variation between decrement time to 1.5 µg.mL-1 and recovery time of over 5 min in nearly half of patients. Decrement time to 1.5 µg.mL-1 must be used with caution when trying to predict recovery time for individual patients following TIVA.

The safety profile and effectiveness of propofol-remifentanil mixtures for total intravenous anesthesia in children.

BACKGROUND: Total intravenous anesthesia is used in less than 10% of operations in the UK. Many pediatric anesthetists in the UK and Ireland administer total intravenous anesthesia to children using a mixture of propofol and remifentanil in the same syringe. This unlicensed drug has not been studied clinically, because of lack of Medicines and Healthcare products Regulatory Agency (UK) or Food and Drug Administration (US) approval to undertake such studies. AIM: The aim of this service evaluation was to assess the safety profile and effectiveness of propofol-remifentanil mixtures in the pediatric population undergoing a variety of surgical procedures. METHODS: Pediatric Anesthetists in the UK and Ireland who regularly used propofol-remifentanil mixtures for total intravenous anesthesia were invited to submit data. This data were analyzed to assess the effectiveness of anesthesia and the incidence and nature of any complications that occurred. RESULTS: Usable data were collected from 873 patients. Mixtures were most commonly administered in gastroenterology and ear, nose, and throat procedures. Two-thirds of patients were less than 10 years old, and their mean weight was 28.7 kg. Anesthesia using the mixture alone was successful in all but 3 patients. The commonest nonserious complication was coughing (4.6%), followed by movement (3.3%). The overall incidence of serious, related, unexpected adverse events requiring intervention was 1.7%. These included desaturation (5 patients), apnea (3), abdominal/chest rigidity (2), cough requiring paralysis (2), ventilatory problems (2), and hypotension (1). Most occurred at induction, were attributable to the properties of the drugs being administered and not directly related to the use of the mixture. No life-threatening adverse events were recorded. Complications were less common if a ≤5 µg mL-1 concentration of remifentanil was used. CONCLUSION: These data demonstrate that effective anesthesia can be administered to pediatric patients undergoing a wide range of procedures using mixtures of propofol and remifentanil. Serious, related, unexpected adverse events requiring intervention had a low incidence and were largely due to predictable effects of the drugs being administered. A ≤5 µg mL-1 remifentanil concentration is associated with proportionately less complications.

Practicalities of Total Intravenous Anesthesia and Target-controlled Infusion in Children.

Propofol administered in conjunction with an opioid such as remifentanil is used to provide total intravenous anesthesia for children. Drugs can be given as infusion controlled manually by the physician or as automated target-controlled infusion that targets plasma or effect site. Smart pumps programmed with pharmacokinetic parameter estimates administer drugs to a preset plasma concentration. A linking rate constant parameter (keo) allows estimation of effect site concentration. There are two parameter sets, named after the first author describing them, that are commonly used in pediatric target-controlled infusion for propofol (Absalom and Kataria) and one for remifentanil (Minto). Propofol validation studies suggest that these parameter estimates are satisfactory for the majority of children. Recommended target concentrations for both propofol and remifentanil depend on the type of surgery, the degree of surgical stimulation, the use of local anesthetic blocks, and the ventilatory status of the patient. The use of processed electroencephalographic monitoring is helpful in pediatric total intravenous anesthesia and target-controlled infusion anesthesia, particularly in the presence of neuromuscular blockade.

A follow-up survey of total intravenous anesthesia usage in children in the U.K. and Ireland.

BACKGROUND: Total intravenous anesthesia usage in children remains relatively unpopular in the UK and Ireland. A postal survey by Hill et al in 2008 indicated that only 26% of Consultants used a propofol infusion at least once a month. AIMS: Following an increase in teaching and training opportunities in pediatric total intravenous anesthesia in the UK, we repeated the survey among Consultant members of Association of Paediatric Anaesthetists of Great Britain and Ireland and Society for Intravenous Anaesthesia, to see if this had affected total intravenous anesthesia usage in children and how practice may have changed. METHODS: We used an anonymous online survey sent to Association of Paediatric Anaesthetists of Great Britain and Ireland and Society for Intravenous Anaesthesia members. RESULTS: A total of 291 responses were analyzed. Total intravenous anesthesia was the default method of anesthesia in 8% of respondents and a further 46% used total intravenous anesthesia at least monthly. Overall total intravenous anesthesia usage had increased in the past year in 53%. The main indications were malignant hyperthermia susceptibility, and postoperative nausea and vomiting. Ear/nose/throat surgery was the most popular surgical specialty. The main reasons for not using total intravenous anesthesia were that it was too "fiddly" and lack of confidence in the user. Most respondents used propofol in combination with remifentanil. Over 80% used propofol target-controlled infusion. The potential for propofol-related infusion syndrome concerned many, with 74% limiting infusion duration as a result. Bispectral Index was not used routinely by the majority of anesthetists. Even though most anesthetists did not use total intravenous anesthesia routinely, 98% felt they would be confident to anesthetize an malignant hyperpyrexia-positive patient using the technique. CONCLUSION: This survey has shown that although total intravenous anesthesia is not the default anesthetic technique for most anesthetists, overall usage in children has more than doubled in the past 10 years, with many happy to use it in a wide variety of patients and procedures.

Neurodevelopmental outcome at 2 years of age after general anaesthesia and awake-regional anaesthesia in infancy (GAS): an international multicentre, randomised controlled trial.

BACKGROUND: Preclinical data suggest that general anaesthetics affect brain development. There is mixed evidence from cohort studies that young children exposed to anaesthesia can have an increased risk of poor neurodevelopmental outcome. We aimed to establish whether general anaesthesia in infancy has any effect on neurodevelopmental outcome. Here we report the secondary outcome of neurodevelopmental outcome at 2 years of age in the General Anaesthesia compared to Spinal anaesthesia (GAS) trial. METHODS: In this international assessor-masked randomised controlled equivalence trial, we recruited infants younger than 60 weeks postmenstrual age, born at greater than 26 weeks' gestation, and who had inguinal herniorrhaphy, from 28 hospitals in Australia, Italy, the USA, the UK, Canada, the Netherlands, and New Zealand. Infants were randomly assigned (1:1) to receive either awake-regional anaesthesia or sevoflurane-based general anaesthesia. Web-based randomisation was done in blocks of two or four and stratified by site and gestational age at birth. Infants were excluded if they had existing risk factors for neurological injury. The primary outcome of the trial will be the Wechsler Preschool and Primary Scale of Intelligence Third Edition (WPPSI-III) Full Scale Intelligence Quotient score at age 5 years. The secondary outcome, reported here, is the composite cognitive score of the Bayley Scales of Infant and Toddler Development III, assessed at 2 years. The analysis was as per protocol adjusted for gestational age at birth. A difference in means of five points (1/3 SD) was predefined as the clinical equivalence margin. This trial is registered with ANZCTR, number ACTRN12606000441516 and ClinicalTrials.gov, number NCT00756600. FINDINGS: Between Feb 9, 2007, and Jan 31, 2013, 363 infants were randomly assigned to receive awake-regional anaesthesia and 359 to general anaesthesia. Outcome data were available for 238 children in the awake-regional group and 294 in the general anaesthesia group. In the as-per-protocol analysis, the cognitive composite score (mean [SD]) was 98.6 (14.2) in the awake-regional group and 98.2 (14.7) in the general anaesthesia group. There was equivalence in mean between groups (awake-regional minus general anaesthesia 0.169, 95% CI -2.30 to 2.64). The median duration of anaesthesia in the general anaesthesia group was 54 min. INTERPRETATION: For this secondary outcome, we found no evidence that just less than 1 h of sevoflurane anaesthesia in infancy increases the risk of adverse neurodevelopmental outcome at 2 years of age compared with awake-regional anaesthesia. FUNDING: Australia National Health and Medical Research Council (NHMRC), Health Technologies Assessment-National Institute for Health Research UK, National Institutes of Health, Food and Drug Administration, Australian and New Zealand College of Anaesthetists, Murdoch Childrens Research Institute, Canadian Institute of Health Research, Canadian Anesthesiologists' Society, Pfizer Canada, Italian Ministry of Heath, Fonds NutsOhra, and UK Clinical Research Network (UKCRN).

Predictors of Failure of Awake Regional Anesthesia for Neonatal Hernia Repair: Data from the General Anesthesia Compared to Spinal Anesthesia Study--Comparing Apnea and Neurodevelopmental Outcomes.

BACKGROUND: Awake regional anesthesia (RA) is a viable alternative to general anesthesia (GA) for infants undergoing lower abdominal surgery. Benefits include lower incidence of postoperative apnea and avoidance of anesthetic agents that may increase neuroapoptosis and worsen neurocognitive outcomes. The General Anesthesia compared to Spinal anesthesia study compares neurodevelopmental outcomes after awake RA or GA in otherwise healthy infants. The aim of the study is to describe success and failure rates of RA and report factors associated with failure. METHODS: This was a nested cohort study within a prospective, randomized, controlled, observer-blind, equivalence trial. Seven hundred twenty-two infants 60 weeks or less postmenstrual age scheduled for herniorrhaphy under anesthesia were randomly assigned to receive RA (spinal, caudal epidural, or combined spinal caudal anesthetic) or GA with sevoflurane. The data of 339 infants, where spinal or combined spinal caudal anesthetic was attempted, were analyzed. Possible predictors of failure were assessed including patient factors, technique, experience of site and anesthetist, and type of local anesthetic. RESULTS: RA was sufficient for the completion of surgery in 83.2% of patients. Spinal anesthesia was successful in 86.9% of cases and combined spinal caudal anesthetic in 76.1%. Thirty-four patients required conversion to GA, and an additional 23 patients (6.8%) required brief sedation. Bloody tap on the first attempt at lumbar puncture was the only risk factor significantly associated with block failure (odds ratio = 2.46). CONCLUSIONS: The failure rate of spinal anesthesia was low. Variability in application of combined spinal caudal anesthetic limited attempts to compare the success of this technique to spinal alone.

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.

Anaesthetic considerations in paediatric myasthenia gravis.

Myasthenia gravis is of particular interest to anaesthetists because of the muscle groups affected, the pharmacology of the neuromuscular junction, and interaction of both the disease and treatment with many anaesthetic drugs. Anaesthetists may encounter children with myasthenia either to facilitate treatment options or to institute mechanical ventilation in the face of a crisis. This paper reviews the literature pertaining to the pathophysiology and applied pharmacology of the disease and explores the relationship between these and the anaesthetic management. In addition to illustrating the tried-and-tested techniques, some newer management options are explored.

A case of acute papillary muscle rupture in a child with campylobacter enteritis and citrullinaemia.

We report a case of acute papillary muscle rupture associated with intercurrent Campylobacter jejuni gastroenteritis in a child with a diagnosis of citrullinaemia, requiring urgent mitral valve replacement.

A combination of total intravenous anesthesia and thoracic epidural for thymectomy in juvenile myasthenia gravis.

Juvenile myasthenia gravis is the acquired form of the disease in children and presents with ocular signs, fatigability, weakness and bulbar problems. The majority of patients demonstrate thymic hyperplasia and have been shown to benefit from thymectomy. The main considerations for the anesthesiologist are the degree of muscle weakness, the muscle groups involved and sensitivity to neuromuscular blocking drugs and volatile agents. Total intravenous anesthesia (TIVA) with epidural analgesia is probably the anesthetic technique of choice, although the latter is often avoided, because of the risk of a very high block. Two cases of thymectomy are presented where anesthesia was provided using a combination of TIVA and thoracic epidural analgesia. Both patients tolerated the technique well and had an uncomplicated perioperative course.