Effect of intravenous lignocaine infusion on bispectral index during spinal anaesthesia for caesarean section: A prospective randomised double-blind study

Background and Aims:

Systemic lignocaine has been shown to have sedative effects. We designed this randomised-double-blind, placebo-controlled study to evaluate the effect of intravenous lignocaine on the bispectral index (BIS) during caesarean section under spinal anaesthesia.

Methods:

80 patients scheduled for elective caesarean section under spinal anaesthesia were randomly allocated to 2 study groups. Group L received intravenous 1.5 mg/kg of lignocaine bolus, 15 minutes before spinal anaesthesia followed by an intravenous infusion 1.5 mg/kg/h for 60 minutes intravenously. The patients in the control group (C group) were given 0.9% sodium chloride in a double-blind fashion. Spinal anaesthesia was performed with 10 mg of 0.5% bupivacaine. The changes of Sao2, BIS and hemodynamic variables during caesarean section, Apgar score of neonate and the incidence of adverse effects were recorded.

Results:

BIS values were lower in the L group compared to C group (P ≤ 0.001). Comparison of mean arterial pressure (MAP) changes during spinal anaesthesia and surgery reveal statistically significant difference between two groups through repeated measure analysis (P ≤ 0.001), but comparision of heart rate (HR) changes during spinal anaesthesia and surgery failed to reveal any statistically significant difference between two groups. (P = 0.261). The Apgar scores did not reveal a significant difference between the two groups at first and five minutes after delivery (P = 0.99).

Conclusion:

Intravenous lignocaine infusion given with spinal anaesthesia in women undergoing elective caesarean delivery providing lower BIS values without respiratory depression, in the absence of foetal compromise.

Modelling of the Sedative Effects of Propofol in Patients undergoing Spinal Anaesthesia: A Pharmacodynamic Analysis

Sedation can increase patient comfort during spinal anaesthesia. Understanding the relationship between the propofol effect-site concentration (Ce) and patient sedation level could help clinicians achieve the desired sedation level with minimal side effects. We aimed to model the relationship between the propofol Ce and adequate and deep sedation and also incorporate covariates. Thirty patients scheduled for orthopaedic surgery received spinal anaesthesia with 0.5% bupivacaine. Propofol was administered via an effect-site target-controlled infusion device using the Schnider pharmacokinetic model. The pharmacodynamic models for both adequate sedation [Observer's Assessment of Alertness/Sedation (OAA/S) scores of 3-4] and deep sedation (OAA/S scores of 1-2) were developed using nonlinear mixed-effects modelling. Increments in the propofol Ce were associated with increased depths of sedation. In the basic model, the estimated population Ce50 values for adequate and deep sedation were 0.94 and 1.52 μg/ml, respectively. The inclusion of the patient's age and sensory block level for adequate sedation and of age for deep sedation as covariates significantly improved the basic model by decreasing the objective function's minimum value from 10696.72 to 10677.92 (p = 0.0003). The simulated Ce50 values for adequate sedation in 20-year-old patients with a T12 sensory level and in 80-year-old patients with a T4 level were 1.63 and 0.53 μg/ml, respectively. Both age and sensory block level should be considered for adequate sedation, and the propofol concentration should be reduced for elderly patients with a high spinal block to avoid unnecessarily deep levels of sedation.

Contemporary perioperative management of adult familial dysautonomia (Riley-Day syndrome)

Familial dysautonomia (Riley-Day syndrome) is a rare multisystem disorder associated with an excess risk of perioperative morbidity and mortality. Because life expectancy is limited, few reports consider the perioperative management of familial dysautonomia in adults with advanced disease and end-organ dysfunction. Here, we report on the management of an adult patient with familial dysautonomia, highlighting recent developments in perioperative technology and pharmacology of special relevance to this challenging population.

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.

Arousal time from sedation during spinal anaesthesia for elective infraumbilical surgeries: Comparison between propofol and midazolam

Background and Aims:

Studies have already compared propofol and midazolam as sedatives during regional anaesthesia. A few studies have focused on recovery characteristics and very few have utilised both instrumental and clinical sedation monitoring for assessing recovery time. This study was designed primarily to compare arousal time from sedation using propofol with that of midazolam during spinal anaesthesia for infraumbilical surgeries, while depth of sedation was monitored continuously with bispectral index (BIS) monitor. The correlation between the BIS score and observer's assessment of awareness/sedation (OAA/S) score during recovery from sedation was also studied.

Methods:

A total of 110 patients were randomly assigned to receive either propofol (Group P, n = 55) or midazolam (Group M, n = 55). Patients in the Group P received bolus of propofol (1 mg/kg), followed by infusion at 3 mg/kg/h; Group M received bolus of midazolam (0.05 mg/kg), followed by infusion at 0.06 mg/kg/h and titration until BIS score 70 was achieved and maintained between 65 and 70. OAA/S score was noted at BIS 70 and again at BIS 90 during recovery. The time to achieve OAA/S score 5 was noted. Spearman's correlation was calculated between the arousal time from sedation and the time taken to reach an OAA/S score of 5 in both the study groups.

Results:

Arousal time from sedation was found lower for Group P compared to Group M (7.54 ± 3.70 vs. 15.54 ± 6.93 min, respectively, P = 0.000). The time taken to reach OAA/S score 5 was also found to be lower for Group P than Group M (6.81 ± 2.54 min vs. 13.51 ± 6.24 min, respectively, P = 0.000).

Conclusion:

A shorter arousal time from sedation during spinal anaesthesia can be achieved using propofol compared with midazolam, while depth of sedation was monitored with BIS monitor and OAA/S score. Both objective and clinical scoring correlate strongly during recovery from sedation.

Association between bispectral index and age and use of sedative drugs in high spinal anaesthesia

OBJECTIVES

A prospective, randomized, double-blind study using bispectral index values to objectively quantify the sedative effect of high spinal anaesthesia in patients stratified according to age, and to determine whether sedative drugs are associated with additional adverse respiratory and haemodynamic effects in older patients.

METHODS

Patients who were electively scheduled for lower limb or abdominal surgery were recruited and allocated into one of three groups according to their age and whether midazolam and fentanyl were used: younger (20-40 years); and older (61-80 years) with or without midazolam and fentanyl intravenous infusion.

RESULTS

The study recruited a total of 90 patients (n = 30 per group). Intraoperative bispectral index values were significantly lower than preoperative values in all groups. Patients in the older age group had significantly lower intraoperative bispectral index values than younger patients. Older patients were significantly more likely to experience respiratory depression (arterial oxyhaemoglobin saturation <90%) than younger patients.

CONCLUSIONS

The sedative effect of high spinal anaesthesia is greater in older patients than in younger patients, with an increase in respiratory instability.

Limitations of anaesthesia depth monitoring

PURPOSE OF REVIEW

We critically review brain function monitors based on the processed electroencephalogram with regards to signal quality, artefacts and other limitations in clinical performance.

RECENT FINDINGS

Several studies have been showing that depth of anaesthesia monitors based on processed electroencephalogram has limitations that can lead to a wrong interpretation of the level of anaesthesia. Processed electroencephalogram indices can be altered by nonanaesthetic influences ranging from artefacts that affect signal quality and signal processing, adverse effects of some anaesthetic and nonanaesthetic drugs, neuromuscular blocking agents to conditions inherent to the patient such as cerebral tumours, brain ischemia and temperature.

SUMMARY

Clinicians should be aware of the several limitations of the commercial devices intending to monitor the depth of anaesthesia, which may not reflect the real underlying level of unconsciousness.