The effects of caudal local anesthesia blockade on the Bispectral Index during general anesthesia in children

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.

Minimum Alveolar Concentration of Desflurane for Maintaining BIS Below 50 in Children and Effect of Caudal Analgesia on it

Context:

Neuraxial techniques have sedative properties secondary to decreased inputs from sensory and motor afferents. We hypothesized that caudal analgesia decreases the requirement of desflurane as measured by bispectral index (BIS).

Aims:

This study aims to determine the minimum alveolar concentration (MAC) of desflurane for maintaining BIS below 50 (MACBIS₅₀) in children undergoing infraumbilical surgeries with laryngeal mask airway (LMA) and study the effect of caudal analgesia on the same.

Settings and Design:

This is prospective and observational study.

Subjects and Methods:

Thirty-nine American Society of Anesthesiologists physical status Classes I and II children in between 1 and 8 years of age undergoing elective infraumbilical surgery under general anesthesia were allocated randomly into two groups (Group C and Group D) after induction with sevoflurane and LMA insertion. In Group C, caudal block was performed with 0.75 mL/kg of 0.25% bupivacaine and BIS values were recorded after 10 min for 1 min at 10 s intervals. In Group D, BIS was recorded for desflurane for 1 min at 10 s intervals followed by a caudal block with the same dose.

Statistical Analysis Used:

Dixon up-down method with a step size of 0.5%, and probit analysis were used for analysis.

Results:

A total of 39 patients were enrolled. MAC of desflurane for maintaining MACBIS₅₀ was 5.57 (95% confidence interval [CI] 5.22–5.95) in Group D and 4.31 (95% CI 3.12–5.08) in Group C. The use of caudal anesthesia lowered the MAC of desflurane for maintaining MACBIS₅₀ in children by 22.36% (P < 0.001).

Conclusions:

The use of caudal analgesia significantly reduced MAC of desflurane for maintaining MACBIS₅₀ in children undergoing infraumbilical surgeries using LMA.

A study of the effect of caudal epidural block on bispectral index targeted propofol requirement in children: A comparative study

Caudal epidural block is one of the most commonly performed neuraxial block techniques with reliable peri-operative and post-operative analgesia in pediatric patients. In our randomized, prospective, double-blinded, open level, parallel group study, we have established the effect of caudal epidural block on maintenance requirement of intravenous (IV) propofol in targeted bispectral (BIS) monitored patients.

Context:

Neuraxial anesthesia exhibits sedative properties that may reduce the requirement for general anesthesia. TIVA with propofol has been administered as an established method of maintaining general anesthesia in children. Caudal analgesia being a type of neuraxial block, also seems to reduce the requirement of sedative hypnotics in pediatric patients. Numerous studies show that for patients, administered with caudal epidural block, they require reduced intra-operative volatile inhalation anesthetics. In the present study, we have established the anesthetic sparing effect of Caudal Epidural Analgesia in children undergoing infra-umbilical surgical procedure and calculated the efficacy of propofol-infusion in maintaining adequate depth of anesthesia.

Aims:

(1) To study and compare the dose requirements of propofol using caudal epidural analgesia. (2) To calculate the efficacy of propofol as maintenance anesthetic agent in both groups and to compare hemodynamic stability of patients in both the techniques.

Settings and Design:

In our study, after administering general anesthesia to pediatric patients, we have administered caudal analgesia and IV analgesia to monitor the requirement of intra-operative propofol infusion using BIS monitor with a target value of 40-60 in both groups.

Materials and Methods:

82 patients (aged between 3 and 6 years) have been selected undergoing infra-umbilical surgery and randomly allocated into two groups containing 41 patients in each group. Both the groups group B and group A then intubated with glycopyrrolate, 2 mg/kg injection fentanyl, propofol till loss of verbal contact and atracurium at the rate of 0.5 mg/kg and group B has been administered caudal epidural blockade with 1 ml/kg 0.2% ropivacaine. Propofol infusion at the rate of 10 mg/kg/h is given as maintenance. BIS value has been recorded throughout and propofol requirement at the end of surgery has been calculated.

Statistical Analysis Used:

Numerical variables between groups have been analyzed using the Student's t-test and the Mann-Whitney U-test as applicable. Categorical variables have been analyzed using the Pearson's Chi-square test. P < 0.05 is considered statistically significant.

Results:

Consumption of propofol at the start of operation in the group A is 2.9 ± 0.17 and group B is 2.91 ± 0.17, which is not statistically significant (P > 0.05), whereas at the end of the operation in the group A is 11.33 ± 0.17 and group B is 7.83 ± 0.63, which is statistically significant (P < 0.05). Incidence of adverse effects is statistically insignificant between the two groups. The time for administration of rescue analgesic is 2.1 ± 0.88 in group A and 6.5 ± 0.17 in group B, which is statistically significant due to caudal analgesia.

Conclusions:

We conclude that in BIS-monitored patients (3-6 years) with infra-umbilical surgeries have shown a reduction in consumption of IV propofol due to caudal epidural blockade.

Caudal block and emergence delirium in pediatric patients: Is it analgesia or sedation?

BACKGROUND

Emergence delirium (ED) although a short-lived and self-limiting phenomenon, makes a child prone to injury in the immediate postoperative period and hence is a cause of concern not only to the pediatric anesthesiologist, surgeons, and post anesthesia care unit staff but also amongst parents. Additional medication to quieten the child offsets the potential benefits of rapid emergence and delays recovery in day care settings. There is conflicting evidence of influence of analgesia and sedation following anesthesia on emergence agitation. We hypothesized that an anesthetic technique which improves analgesia and prolongs emergence time will reduce the incidence of ED. We selected ketamine as adjuvant to caudal block for this purpose.

METHODS

This randomized, double blind prospective study was performed in 150 premedicated children ASA I, II, aged 2 to 8 years who were randomly assigned to either group B (caudal with bupivacaine), BK (bupivacaine and ketamine), or NC (no caudal), soon after LMA placement. Recovery characteristics and complications were recorded.

RESULTS

Emergence time, duration of pain relief, and Pediatric Anesthesia Emergence Delirium (PAED) scores were significantly higher in the NC group (P<0.05). Duration of analgesia and emergence time were significantly more in group BK than groups B and NC. However, the discharge readiness was comparable between all groups. No patient in BK group required to be given any medication to treat ED.

CONCLUSION

Emergence time as well as duration of analgesia have significant influence on incidence of emergence delirium. Ketamine, as caudal adjuvant is a promising agent to protect against ED in children, following sevoflurane anesthesia.