Sedation during spinal anaesthesia in infants

A Single Center's Experience With Spinal Anesthesia for Pediatric Patients Undergoing Surgical Procedures

PURPOSE

To perform a single institution review of spinal instead of general anesthesia for pediatric patients undergoing surgical procedures. Spinal success rate, intraoperative complications, and postoperative outcomes including unplanned hospital admission and emergency department visits within seven days are reported.

METHODS

Retrospective chart review of pediatric patients who underwent spinal anesthesia for surgical procedures from 2016 until 2022. Data collected included patient demographics, procedure and anesthetic characteristics, intraoperative complications, unplanned admissions, and emergency department returns.

RESULTS

The study cohort included 1221 patients. Ninety-two percent of the patients tolerated their surgical procedure without requiring conversion to general anesthesia, and 78% of patients that had spinals placed successfully did not receive any sedation following lumbar puncture. The most common intraoperative event was systolic blood pressure below 60 mm Hg (14%), but no cases required administration of vasoactive agents, and no serious intraoperative adverse events were observed. Post-Anesthesia Care Unit Phase I was bypassed in 72% of cases with a median postoperative length of stay of 84 min. Forty-six patients returned to the emergency department following hospital discharge, but no returns were due to anesthetic concerns.

CONCLUSIONS

Spinal anesthesia is a viable and versatile option for a diversity of pediatric surgical procedures. We noted a low incidence of intraoperative and postoperative complications. There remain numerous potential advantages of spinal anesthesia over general anesthesia in young pediatric patients particularly in the ambulatory setting.

LEVEL OF EVIDENCE

IV.

TYPE OF STUDY

Retrospective cohort treatment study.

Age-Dependent Electroencephalogram Features in Infants Under Spinal Anesthesia Appear to Mirror Physiologic Sleep in the Developing Brain: A Prospective Observational Study

BACKGROUND

Infants under spinal anesthesia appear to be sedated despite the absence of systemic sedative medications. In this prospective observational study, we investigated the electroencephalogram (EEG) of infants under spinal anesthesia and hypothesized that we would observe EEG features similar to those seen during sleep.

METHODS

We computed the EEG power spectra and spectrograms of 34 infants undergoing infraumbilical surgeries under spinal anesthesia (median age 11.5 weeks postmenstrual age, range 38-65 weeks postmenstrual age). Spectrograms were visually scored for episodes of EEG discontinuity or spindle activity. We characterized the relationship between EEG discontinuity or spindles and gestational age, postmenstrual age, or chronological age using logistic regression analyses.

RESULTS

The predominant EEG patterns observed in infants under spinal anesthesia were slow oscillations, spindles, and EEG discontinuities. The presence of spindles, observed starting at about 49 weeks postmenstrual age, was best described by postmenstrual age ( P =.002) and was more likely with increasing postmenstrual age. The presence of EEG discontinuities, best described by gestational age ( P = .015), was more likely with decreasing gestational age. These age-related changes in the presence of spindles and EEG discontinuities in infants under spinal anesthesia generally corresponded to developmental changes in the sleep EEG.

CONCLUSIONS

This work illustrates 2 separate key age-dependent transitions in EEG dynamics during infant spinal anesthesia that may reflect the maturation of underlying brain circuits: (1) diminishing discontinuities with increasing gestational age and (2) the appearance of spindles with increasing postmenstrual age. The similarity of these age-dependent transitions under spinal anesthesia with transitions in the developing brain during physiological sleep supports a sleep-related mechanism for the apparent sedation observed during infant spinal anesthesia.

Single-Shot Spinal Anesthesia in an Infant Requiring Magnetic Resonance Imaging and Open Lower-Extremity Surgery: A Case Report

Spinal anesthesia (SA) is a safe and effective anesthetic technique for lower abdominal and lower extremity surgery in neonates and infants and is associated with an apparent state of sedation. We report the use of single-shot SA in a 6-week-old infant for a combined magnetic resonance imaging and open surgical biopsy of a deep soft tissue lower extremity mass. By leveraging the unique qualities of SA (sedation and surgical blockade), we avoided the need for general anesthesia. To our knowledge, this is the first reported use of single-shot SA for an infant undergoing two procedures in the same day.

Implementation of a spinal anesthesia and sedation protocol that reliably prolongs infant spinal anesthesia: Case series of 102 infants who received spinal anesthesia for urologic surgery

BACKGROUND

The use of spinal anesthesia in infants is seeing resurgence as an alternative to general anesthesia.

AIMS

Our primary aims are to describe our institution's experience introducing a spinal anesthesia and sedation protocol for infants undergoing urologic surgery, to describe methods of improving prolonged anesthesia, and to describe the failure rate of spinal anesthesia in these patients. Sedation was provided for some infants with intranasal dexmedetomidine ± fentanyl.

METHODS

This is a retrospective case series examining infants aged 1-<14 months who received spinal anesthesia for circumcision, orchiopexy, orchiectomy, hypospadias repair, or epispadias repair. The electronic medical record was reviewed and compared with unmatched historical controls who received general anesthesia.

RESULTS

A total of 230 patients underwent a urologic procedure; 102 patients received spinal anesthesia and 128 received general anesthesia. Length of surgical time with spinal anesthesia ranged from 4 to 189 minutes. The hospital length of stay was shorter in the spinal anesthesia group (median [IQR] of 5.3 hours [4.3, 7.2]) compared to the general anesthesia group (17.1 hours [15.6, 17.5]).The median bupivacaine dose was 0.75 mg/kg [0.67, 0.85]. There was one case in which cerebral spinal fluid was unable to be obtained, and one case that required conversion to general anesthesia after surgery had started. There were no cases of apnea, bleeding, infection, or neurologic compromise.

CONCLUSIONS

We describe the successful implementation of an infant spinal anesthesia and sedation protocol and a technique that uniquely provides prolonged surgical anesthesia with a low failure rate. We also report shorter anesthesia time, surgical time, and recovery room length of stay in patients who received spinal anesthesia compared to general anesthesia.

Use of spinal anaesthesia in neonates and infants in Antananarivo, Madagascar: a retrospective descriptive study

Objective

The aim of this study was to present the first cases of spinal anesthesia, in newborns and infants, preterm/ex-prematures, in order to determine its feasibility and its potential harmlessness, in Antananarivo—Madagascar. Indeed, spinal anesthesia is a low cost technique and can limit respiratory complications, postoperative apnea a contrario with pediatric general anesthesia which can lead to perioperative risks.

Results

In a retrospective, descriptive, 7-year (2013 to 2019) period study, conducted in the University Hospital Joseph Ravoahangy Andrianavalona, 69 patients’ data files planned to have spinal anesthesia were recorded. These pediatric patients were predominantly male (sex ratio = 2.8) and 37 [28–52] days old. The smallest anesthetized child weighed 880 g; the youngest was 4 days old. Twenty-seven (27) of them were premature and 20.3% presented respiratory diseases. They were mostly scheduled for hernia repair (90%). Spinal anesthesia was performed, with a Gauge 25 Quincke spinal needle, after 2 [1–2] attempts with hyperbaric bupivacaine of 4 [3.5–4] mg. Failure rate was 5.8%. The heart rate was stable throughout perioperative period and no complications were observed.

Epidural and Spinal Anesthesia for Newborn Surgery

Neuraxial (spinal and epidural) anesthesia has become commonplace in the care of neonates undergoing surgical procedures. These techniques afford many benefits, and, when properly performed, are extremely safe. This article reviews the benefits, risks, and applications of neuraxial anesthesia in neonates.

Spinal anesthesia in infants and children: A one year prospective audit

Context and Aims:

Spinal anesthesia though gaining popularity in children, the misconceptions regarding its safety and feasibility can be better known with greater use and experience. The objective of this study was to evaluate the success rate, complications and hemodynamic stability related to pediatric spinal anesthesia.

Materials and Methods:

In this 1-year prospective study, 102 pediatric patients aged 6 months to 14 years undergoing infraumbilical and lower extremity surgery were included. Spinal anesthesia was administered using hyperbaric bupivacaine 0.5% in a dose of 0.5 mg/kg (for child < 5 kg), 0.4 mg/kg (for 5-15 kg), 0.3 mg/kg (for >15 kg) in L4-L5 space under all aseptic precautions after sedation. Demographic data, vital parameters, supplemental sedation, number of attempts for lumbar puncture, sensory-motor block characteristics, and complications were noted.

Results:

Spinal anesthesia was successful in 98 (97.1%) patients. Remaining 4 (3.9%) were failures and were given general anesthesia. Lumbar puncture was successful in first attempt (60 [58.82%]) or 2^nd attempt (42 [41.18%]). There was no significant change in vital parameters. Mean peak sensory level was T 6.35 ± 1.20 (T4-T8). Mean sensory level at the end of surgery was T 8.11 ± 1.42 (T6-T10). Modified Bromage score was 3 in 98 (96.08%) patients. Sensory and motor block recovery was complete in all patients. Mean time to two segment regression was 43.97 ± 10.72 (30-70) min. Mean time to return Bromage score to 0 was 111.95 ± 20.54 (70-160). Mean duration of surgery was 52.5 ± 16.056 (25-95) min. Incidence of complications was minimal with hypotension occurring in 2 (2%) and shivering in 3 (2.9%) patients.

Conclusion:

Pediatric spinal anesthesia is a safe and effective anesthetic technique for lower abdominal and lower limb surgeries of shorter duration (<90 min) with high success rate. Owing to, its early motor recovery, it can be a preferred technique for day case surgeries in the pediatric population.

Spinal anaesthesia for orthopaedic surgery in children with cerebral palsy: Analysis of 36 patients

BACKGROUND AND OBJECTIVE

Cerebral palsy is one of the most common childhood neuromuscular diseases in the world. Spinal anaesthesia in children is an evolving technique with many advantages in perioperative management. The aim of this retrospective study was to provide first-hand reports of children with cerebral palsy who underwent orthopaedic surgery under spinal anaesthesia.

METHODS

Records of the children with cerebral palsy who underwent orthopaedic surgery under spinal anaesthesia between May 2012 and June 2013 at Selcuk University Hospital were investigated. In all patients, lumbar puncture was performed in lateral decubitus position with mask sevoflurane-nitrous oxide anaesthesia. In patients who were calm prior the spinal block, inhalation anaesthesia was terminated. In patients who were restless before the spinal block, anaesthesia was combined with light sevoflurane anaesthesia and a laryngeal mask. From anaesthesia records, the number of attempts required to complete the lumbar puncture, and the success rates of spinal anaesthesia and perioperative complications were noted. Data were expressed as numbers and percentages.

RESULTS

The study included 36 patients (20 girls and 16 boys). The mean age was 71 months. The rate of reaching subarachnoid space on first attempt was 86%. In all patients, spinal anaesthesia was considered successful. In 26 patients, laryngeal mask and light sevoflurane anaesthesia were required to maintain ideal surgical conditions. No major perioperative complications were observed.

CONCLUSION

Spinal anaesthesia alone or combined with light sevoflurane anaesthesia is a reliable technique with high success rates in children with cerebral palsy undergoing orthopaedic surgery.

[Central blockades in Pediatrics: A review of current literature]

Pediatric neuraxial anesthesia is an effective tool that can be used as a supplement or alternative to general anesthesia. However, there have always been doubts about its usefulness and risk-benefit ratio. The purpose of this review is to describe the current role of central blockades in pediatric patients, upgrade practical and safety aspects, and review the latest technological advances applied to this procedure.

Spinal anesthesia in children: A review

Even after a vast safety record, the role of spinal anesthesia (SA) as a primary anesthetic technique in children remains contentious and is mainly limited to specialized pediatric centers. It is usually practiced on moribund former preterm infants (<60 weeks post-conception) to reduce the incidence of post-operative apnea when compared to general anesthesia (GA). However, there is ample literature to suggest its safety and efficacy for suitable procedures in older children as well. SA in children has many advantages as in adults with an added advantage of minimal cardio-respiratory disturbance. Recently, several reports from animal studies have raised serious concerns regarding the harmful effects of GA on young developing brain. This may further increase the utility of SA in children as it provides all components of balanced anesthesia technique. Also, SA can be an economical option for countries with finite resources. Limited duration of surgical anesthesia in children is one of the major deterrents for its widespread use in them. To overcome this, several additives like epinephrine, clonidine, fentanyl, morphine, neostigmine etc. have been used and found to be effective even in neonates. But, the developing spinal cord may also be vulnerable to drug-related toxicity, though this has not been systematically evaluated in children. So, adjuvants and drugs with widest therapeutic index should be preferred in children. Despite its widespread use, incidence of side-effects is low and permanent neurological sequalae have not been reported with SA. Literature yields encouraging results regarding its safety and efficacy. Technical skills and constant vigilance of experienced anesthesia providers is indispensable to achieve good results with this technique.

Neuraxial analgesia in neonates and infants: a review of clinical and preclinical strategies for the development of safety and efficacy data

Neuraxial drugs provide robust pain control, have the potential to improve outcomes, and are an important component of the perioperative care of children. Opioids or clonidine improves analgesia when added to perioperative epidural infusions; analgesia is significantly prolonged by the addition of clonidine, ketamine, neostigmine, or tramadol to single-shot caudal injections of local anesthetic; and neonatal intrathecal anesthesia/analgesia is increasing in some centers. However, it is difficult to determine the relative risk-benefit of different techniques and drugs without detailed and sensitive data related to analgesia requirements, side effects, and follow-up. Current data related to benefits and complications in neonates and infants are summarized, but variability in current neuraxial drug use reflects the relative lack of high-quality evidence. Recent preclinical reports of adverse effects of general anesthetics on the developing brain have increased awareness of the potential benefit of neuraxial anesthesia/analgesia to avoid or reduce general anesthetic dose requirements. However, the developing spinal cord is also vulnerable to drug-related toxicity, and although there are well-established preclinical models and criteria for assessing spinal cord toxicity in adult animals, until recently there had been no systematic evaluation during early life. Therefore, in the second half of this review, we present preclinical data evaluating age-dependent changes in the pharmacodynamic response to different spinal analgesics, and recent studies evaluating spinal toxicity in specific developmental models. Finally, we advocate use of neuraxial drugs with the widest demonstrable safety margin and suggest minimum standards for preclinical evaluation before adoption of new analgesics or preparations into routine clinical practice.

Spinal blocks

Every anesthetist should have the expertise to perform lumbar puncture that is the prerequisite to induce spinal anesthesia. Spinal anesthesia is easy and effective technique: small amount of local anesthetic injected in the lumbar cerebrospinal fluid provides highly effective anesthesia, analgesia, and sympathetic and motor block in the lower part of the body. The main limitation of spinal anesthesia is a variable and relatively short duration of the block with a single-injection of local anesthetic. With appropriate use of adjuvant or combining spinal anesthesia with epidural anesthesia, the analgesic action can be controlled in case of early recovery of initial block or in patients with prolonged procedures. Contraindications are rare. Bleeding disorders and any major dysfunction in coagulation system are rare in children, but spinal anesthesia should not be used in children with local infection or increased intracranial pressure. Children with spinal anesthesia may develop the same adverse effects as has been reported in adults, but in contrast to adults, cardiovascular deterioration is uncommon in children even with high blocks. Most children having surgery with spinal anesthesia need sedation, and in these cases, close monitoring of sufficient respiratory function and protective airway reflexes is necessary. Postdural puncture headache and transient neurological symptoms have been reported also in pediatric patients, and thus, guardians should be provided instructions for follow-up and contact information if symptoms appear or persist after discharge. Epidural blood patch is effective treatment for prolonged, severe headache, and nonopioid analgesic is often sufficient for transient neurological symptoms.

[Caudal block and light sevoflurane mask anesthesia in high-risk infants: an audit of 98 cases]

OBJECTIVE

In order to reduce the risk of postoperative apnoea, awake spinal anaesthesia or awake caudal anaesthesia are recommended for hernia surgery in newborn babies and former premature infants aged less than 60 weeks of amenorrhoea. However, additional sedation is sometimes necessary. Our working hypothesis was that a general anaesthesia with a face mask (sevoflurane) with no opiates nor neuromuscular blocking agents, maintaining the infant's spontaneous breathing and combined with a caudal anaesthesia, could provide a safe and effective alternative.

STUDY DESIGN

The epidemiological and technical data about the patient and the anaesthesia, as well as any per- and postoperative complications, were collected prospectively and analysed retrospectively.

PATIENTS AND METHODS

Ninety-eight infants undergoing hernia surgery were included during the period from 2003 to 2008.

RESULTS

Caudal anaesthesia proved successful at first attempt in 69% of the infants (term or premature). Three attempts were needed in 8% of the infants born at term and 2% of the infants born prematurely. One failure was recorded. Seven patients presented one episode of peroperative apnoea; they were easily taken care of by means of brief face mask ventilation. The follow-up of these seven infants did not reveal any reappearance of postoperative apnoea/bradypnoea.

CONCLUSION

The technique proposed is an effective alternative to the awake locoregional anaesthesia techniques: it provides excellent conditions for surgery and presents similar perioperative morbidity and risk of postoperative apnoea.

An evaluation of intrathecal bupivacaine combined with intrathecal or intravenous clonidine in children undergoing orthopedic surgery: a randomized double-blinded study

BACKGROUND

Propofol is a popular agent for providing intraoperative sedation in pediatric population during lumbar puncture and spinal anesthesia. Adjuvant-like clonidine is used increasingly in pediatric anesthesia to provide postoperative analgesia with a local anesthetic agent. The aim of this study was to assess the effects of intrathecal and intravenous clonidine on postoperative analgesia/sedation and intraoperative requirements of propofol after intrathecal bupivacaine for orthopedic surgery in children.

METHODS

Fifty-nine ASA I and II children aged 6-8 year undergoing orthopedic surgery were randomized to receive intrathecal 0.5% bupivacaine 0.2-0.4 mg·kg(-1) and intravenous 2 ml saline (Group B), intrathecal 0.5% bupivacaine 0.2-0.4 mg·kg(-1) plus 1 μg·kg(-1) clonidine and intravenous 2 ml saline (Group BCit), and 0.5% bupivacaine 0.2-0.4 mg·kg(-1) and intravenous 1 μg·kg(-1) clonidine in 2 ml of saline (Group BCiv). Intraoperative sedation was maintained with 20-50 μg·kg(-1)·min(-1) of propofol infusion. The requirements of propofol, time to first rescue analgesia, and postoperative pain or sedation scores were assessed. The duration of motor and sensory blocks and perioperative adverse events were determined.

RESULTS

Clonidine significantly prolonged the time to first rescue analgesia and reduced the requirements of propofol sedation whether administered intravenously or intrathecally. The mean Children and Infants Postoperative Pain Scale scores of children were significantly lower in groups BCit and BCiv than in group B. Postoperative sedation scores were higher in groups BCit and BCiv than in group B. Intrathecal clonidine significantly prolonged the time to regression of the sensory block and recovery of motor block. There were no significant differences among the three groups regarding the incidence of perioperative adverse events.

CONCLUSION

Intrathecal or intravenous clonidine similarly provided better postoperative analgesia and sedation and reduced the requirements of propofol. Only intrathecal clonidine prolonged the duration of sensory and motor blocks.

Intrathecal clonidine decreases propofol sedation requirements during spinal anesthesia in infants

BACKGROUND

Propofol is a popular agent for providing procedural sedation in pediatric population during lumbar puncture and spinal anesthesia. Adjuvants like clonidine and fentanyl are administered intrathecally to prolong the duration of spinal anesthesia and to provide postoperative analgesia. We studied the propofol requirement after intrathecal administration of clonidine or fentanyl in infants undergoing lower abdominal surgeries.

METHODS

Sixty-five ASA I infants undergoing elective lower abdominal surgery under spinal anesthesia were assigned into four groups in this prospective randomized double-blinded study. Group B received bupivacaine based on body weight (<5 kg = 0.5 mg kg(-1); 5-10 kg = 0.4 mg kg(-1)). Group BC received 1 microg kg(-1) of clonidine with bupivacaine, group BF received 1 microg kg(-1) of fentanyl with bupivacaine, and patients in group BCF received 1 microg kg(-1) each of clonidine and fentanyl with bupivacaine. A bolus of 2-3 mg kg(-1) of propofol bolus was administered for lumbar puncture. Sedation was assessed using a six-point sedation score (0-5) and a five-point reactivity score (0-4) which was based on a behavioral score. After achieving a sedation and reactivity score of 3-4, the patients were placed lateral in knee chest position and lumbar puncture performed and test drug administered. Further intraoperative sedation was maintained with an infusion of 25-50 microg kg(-1) min(-1) of propofol infusion.

RESULTS

The mean +/- SD infusion requirement of propofol decreased from 35.5 +/- 4.5 in group B to 33.4 +/- 5.4 microg kg(-1) min(-1) in group BF and further decreased to 16.7 +/- 6.2 microg kg(-1) min(-1) and 14.8 +/- 4.9 microg kg(-1) min(-1) in group BC and BCF, respectively. There were no statistically significant differences between BC and BCF groups. The mean sedation and reactivity scores were higher in groups BC and BCF when compared to groups B and BF.

CONCLUSION

Our study show that the requirement of propofol sedation reduces with intrathecal adjuvants. The reduction was significant with the addition of clonidine and clonidine-fentanyl combination as opposed to bupivacaine alone or with fentanyl. There was no significant difference in propofol infusion requirement with the use of bupivacaine alone or with fentanyl.

Efficacy of a low-dose spinal morphine with bupivacaine for postoperative analgesia in children undergoing hypospadias repair

BACKGROUND

Children undergoing hypospadias repair need to be protected from highly unpleasant sensory and emotional experiences during and after surgery. We designed a double-blinded, randomized, and placebo-controlled study to compare the efficacy of a low-dose (2 microg x kg(-1)) of intrathecal morphine with placebo for postoperative pain control of children undergoing repair of hypospadias surgery with spinal anesthesia.

METHODS

Fifty-four children were randomly assigned to one of two spinal anesthesia groups. Group M (n = 27) received hyperbaric bupivacaine plus 2 microg x kg(-1) of preservative-free morphine and group P (n = 27) received hyperbaric bupivacaine plus 0.9% NaCl (placebo) under inhalation anesthesia. General anesthetics were discontinued subsequent to the block. The primary outcome was the presence of pain-requiring analgesics during the first 12 h after the spinal block. Side effects were also recorded. The analgesic effects were evaluated by using the Children's Hospital of Eastern Ontario Pain Scale.

RESULTS

Forty-nine patients completed the trial. Fifteen patients (60%) in group P received supplementary analgesics within the first 12 h compared to only four patients (16.7%) in group M (P = 0.005). Mean duration of analgesia was 480 +/- 209 and 720 +/- 190 min in group P and group M respectively (P = 0.009). The groups were similar in postoperative side effects.

CONCLUSION

Spinal anesthesia provided by hyperbaric bupivacaine is adequate for distal hypospadias repair in children, but adding 2 microg x kg(-1) intrathecal morphine provides better postoperative pain control when compared to placebo in these children.

Depth of sedation using Cerebral State Index in infants undergoing spinal anesthesia

BACKGROUND

Infants are noted to frequently sleep during spinal anesthesia, with a concomitant fall in Bispectral Index. However, there are suggestions that EEG derived anesthesia depth monitors have inferior performance in infants. The aim of this study was to quantify the degree of sedation during spinal anesthesia in infants using another EEG derived measure of anesthesia effect--the Cerebral State Index (CSI).

METHODS

Twelve infants, <52 weeks postconceptual menstrual age, scheduled for bilateral inguinal hernia repair under spinal anesthesia were enrolled. Patients received a standard anesthetic protocol with a subarachnoid dose of 1 mg x kg(-1) of levobupivacaine 0.5%. No premedication, sedatives, opioids or anticholinergics were administrated during the perioperative period and patients were left undisturbed during the surgical time, without tactile stimulation or loud auditory stimuli. CSI score (0-100) and bust suppression (BS) (0-100%) were continuously recorded during the surgical time and then statistically re-evaluated.

RESULTS

In all patients the CSI fell during the procedure and there were significant levels of BS recorded by the CSI monitor. The BS occurred between 12 and 34 min after spinal anesthesia with the peak being at 30 min and mean onset time being 15 (2.6) min after spinal block. A statistical significant difference was found between the lowest mean CSI as well as the highest BS if compared with their baseline values. A negative correlation was found between CSI and BS.

CONCLUSIONS

The degree of burst suppression detected by the CSI in our study supports the hypothesis that infants may have discontinuous patterns of EEG during spinal anesthesia similar to those seen during emergence from general anesthesia. Moreover, the limitations in the application of the adult algorithms to infant EEG may lead to an overestimation of the degree of sedation.

Monitoring the anaesthetic depth in children - an update

PURPOSE OF REVIEW

There are several commercially available electroencephalogram-derived devices for monitoring anaesthesia depth. This article reviews all published studies describing their use in children; first assessing studies of performance in measuring anaesthesia depth in observational, physiological studies and then describing relevant outcome studies. There is also a brief discussion of why they might be useful, what physiological problems may arise and what the reader should be wary of in the methodology of these studies. The subject is approached from a clinical perspective.

RECENT FINDINGS

There are several physiological studies suggesting that for older children the bispectral index, entropy, Narcotrend index, cerebral state index and A-line ARX index all change with induction of anaesthesia, and have reasonable correlations with doses of anaesthetic agent. There is consistent evidence that the performances are substantially poorer in infants. Some of these devices have been demonstrated to reduce anaesthesia drug consumption and hasten recovery in older children.

SUMMARY

The bispectral index is the most widely studied, but at this stage there is no evidence to suggest any one device is substantially superior to any other. There may be a role emerging for their use in older children, but their use in infants cannot be supported.