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

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.

Electroencephalographic assessment of infant spinal anesthesia: A pilot prospective observational study

INTRODUCTION

Spinal anesthesia is utilized as an alternative to general anesthesia in infants for some surgeries. After spinal anesthesia, infants often become less conscious without administration of sedative medications. The aim of this study was to assess electroencephalographic (EEG) correlates after spinal anesthesia in a cohort of infants.

PATIENTS AND METHODS

This pilot study included 12 infants who underwent spinal anesthesia. Unprocessed electroencephalography was recorded. The electroencephalogram was interpreted by four neurologists. Processed analyses compared electroencephalogram changes 30 min after spinal anesthesia to baseline.

RESULTS

Following spinal anesthesia, all 12 infants became sedated. Electroencephalography in all 12 demonstrated Stage 2 sleep with the appearance of sleep spindles (12-14 Hz) in the frontal and central leads in 8/12 (67%) of subjects. The median time to onset of sleep spindles was 24.7 interquartile range (21.2, 29.9) min. The duration of sleep spindles was 25.1 interquartile range (5.8, 99.8) min. Voltage attenuation and background slowing were the most common initial changes. Compared to baseline, the electroencephalogram 30 min after spinal anesthesia showed significantly increased absolute delta power (p = 0.02) and gamma power (p < 0.0001); decreases in beta (p = 0.0006) and higher beta (p < 0.0001) were also observed. The Fast Fourier Transform power ratio difference for delta/beta was increased (p = 0.03). Increased coherence was noted in the delta (p = 0.02) and theta (p = 0.04) bandwidths.

DISCUSSION

Spinal anesthesia in infants is associated with increased electroencephalographic slow wave activity and decreased beta activity compared to the awake state, with appearance of sleep spindles suggestive of normal sleep. The etiology and significance of the observed voltage attenuation and background slowing remains unclear.

CONCLUSIONS

The EEG signature of infant spinal anesthesia is distinct from that seen with general anesthesia and is consistent with normal sleep. Further investigation is required to better understand the etiology of these findings. Our preliminary findings contribute to the understanding of the brain effects of spinal anesthesia in early development.

Perioperative sedation requirements of infants aged 0 to 3 months subjected to lower-body surgery under caudal blockade: a randomized controlled trial

BACKGROUND

It remains unclear how much sedation is required for subumbilical surgery under caudal blockade, and sedatives may carry a poorly understood risk of late sequelae in infants. We designed a randomized controlled study to evaluate total propofol consumption and perioperative sedation quality with the avoidance of continuous perioperative sedation in infants undergoing surgery under caudal anesthesia.

METHODS

Thirty-two infants (age: 0-3 months) were randomized to one of two groups in which perioperative administration of propofol was provided either "as needed" or by continuous infusion (5 mg kg-1 h-1). After induction of anesthesia via a facemask with sevoflurane, a venous access was established and 1 ml kg-1 of ropivacaine 0.35% was injected for caudal anesthesia. Intraoperative stress was assessed by repeated recording Comfort Behavioral Scale scores and heart rates.

RESULTS

Significantly (p = 0.0001) less propofol was administered in the as-needed group (0.7 ± 1.4 mg/kg) than in the continuous-infusion group (3.0 ± 1.6 mg/kg). This difference was not reflected in different requirements of additional intraoperative sedation (0.5 ± 0.8 mg/kg in 5 versus 0.6 ± 1.0 mg/kg in 4 cases; p = 0.76).

CONCLUSIONS

As needed propofol administration offers no disadvantage in terms of intraoperative sedation, but significant dose reductions can be achieved by avoiding continuous propofol infusion.

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.

[Drug-induced sedation endoscopy-quo vadis? : Review and outlook]

BACKGROUND

Drug-induced sedation endoscopy (DISE) is a diagnostic procedure which allows evaluation of the collapsibility of the upper airway. According to expert opinion, it is possible to imitate nocturnal collapsibility and perform a realistic investigation of the site of obstruction and vibration. This should enable sufficient and precise therapeutic advice to be given solely on the basis of clinical assessment.

OBJECTIVE

The current publication critically evaluates the present state of development of DISE and its potential indications.

MATERIALS AND METHODS

A PubMed literature research was performed using "sleep" and "endoscopy" or "DISE" as keywords. Relevant publications were evaluated.

RESULTS

The present publication provides a historical summary of the available publications and relates these to other methods for examining obstructive sleep apnea. The present state of DISE in terms of drugs applied, grading systems, and validity is evaluated. Indications for DISE are described and critically discussed on the basis of literature data.

CONCLUSION

DISE provides deep insights into the genesis of obstructions of the upper airway and snoring. Although its value for diagnosis and treatment of sleep-disordered breathing could not yet be demonstrated for all non-CPAP (continuous positive airway pressure) therapies, DISE could identify predictive parameters some methods. Further potential indications for DISE might be predictive examinations for mandibular advancement devices and respiration-synchronous neurostimulation of the hypoglossal nerve. DISE will thus remain a valuable diagnostic tool for obstructive sleep apnea and rhonchopathy.

Neonatal electroencephalography shows low sensitivity to anesthesia

This study examined EEG under clinical anesthesia in neonates and infants, to clarify how growth affects EEG during anesthesia. Subjects comprised 62 neonates and infants. Patients were divided into four groups according to age: Group 1 (neonates), <1 month; Group 2, 1-2 months; Group 3, 3-5 months; and Group 4, 6 months to 2 years. Anesthesia was maintained with sevoflurane and fentanyl and/or caudal block. At four points of sevoflurane concentration (0.5%, 1%, 1.5%, and 2%), 90% spectral edge frequency (SEF90), burst suppression ratio (BSR), relative beta ratio (RBR) and approximate entropy (ApEn) were analyzed. In Group 4, SEF90, BSR, RBR and ApEn changes were dependent on the concentration of anesthesia, along with changes in sevoflurane concentration from 0.5% to 2% (from 14.3 (2.7) [mean (SD)] Hz to 8.2 (3.8) Hz, from 0.0 to 0.32 (0.36), from -1.58 (0.14) to -1.10 (0.15), and from 0.56 (0.25) to 0.24 (0.25) respectively; p<0.05 each). Conversely, these processed EEG parameters in Group 1 showed little anesthesia-dependent change under sevoflurane concentrations between 0.5% and 2% (SEF90: 7.3 (1.2) Hz vs. 7.7 (2.1) Hz; BSR: 0.51 (0.20) vs. 0.62 (0.29); RBR: -1.00 (0.17) vs. -1.03 (0.27); ApEn: 0.32 (0.18) vs. 0.25 (0.14), respectively). The unique EEG features of neonates during anesthesia rapidly change to the usual anesthesia-dependent patterns seen in older children, with a boundary of 3-5 months old. In infants younger than 6 months old, neural network regulation reflected in EEG by anesthesia is weak.

[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.

Monitoring the depth of anaesthesia

One of the current challenges in medicine is monitoring the patients’ depth of general anaesthesia (DGA). Accurate assessment of the depth of anaesthesia contributes to tailoring drug administration to the individual patient, thus preventing awareness or excessive anaesthetic depth and improving patients’ outcomes. In the past decade, there has been a significant increase in the number of studies on the development, comparison and validation of commercial devices that estimate the DGA by analyzing electrical activity of the brain (i.e., evoked potentials or brain waves). In this paper we review the most frequently used sensors and mathematical methods for monitoring the DGA, their validation in clinical practice and discuss the central question of whether these approaches can, compared to other conventional methods, reduce the risk of patient awareness during surgical procedures.

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.