Bispectral index monitoring for sedation in scheduled adult colonoscopy: A randomized controlled trial

BACKGROUND

Patients should be closely monitored during procedures under sedation outside the operating room, but it is unclear which type of monitoring is best. We investigated the efficacy and safety of BIS monitoring vs conventional monitoring for sedation during colonoscopy.

METHODS

We performed a double-blind clinical trial in 180 patients undergoing elective colonoscopy. Patients were randomized to 1) the BIS group or 2) a control group, in which sedation was monitored with a BIS monitor or the Ramsay Sedation Score, respectively. The primary outcome was the rate of sedation-induced adverse events in both groups. Secondary outcomes were the characteristics of patients who developed adverse events, and time during colonoscopy when these events occurred, propofol and remifentanil dosage, and patient satisfaction.

RESULTS

Univariate analysis showed fewer cardiopulmonary complications in the BIS group (41.11% vs 57.78% in controls; p = 0.02). Multivariate analysis found a significantly higher risk of adverse events in older patients (95% CI, 1.013-1.091; p = 0.0087) and in men (95% CI, 1.129-7.668; p = 0.0272). These events were observed at the hepatic flexure. No significant differences between propofol or remifentanil dosage, use of rescue medication, and patient satisfaction were observed between groups.

CONCLUSIONS

Our data suggest that BIS monitoring during sedation in scheduled colonoscopies reduces adverse respiratory events. Although its routine use in sedation does not appear to be warranted, clinicians should take steps to identify patients with a higher risk of complications who might benefit from this type of monitoring.

Electroencephalographic spectrogram-guided total intravenous anesthesia using dexmedetomidine and propofol prevents unnecessary anesthetic dosing during craniotomy: a propensity score-matched analysis

BACKGROUND

The bispectral index (BIS) may be unreliable to gauge anesthetic depth when dexmedetomidine is administered. By comparison, the electroencephalogram (EEG) spectrogram enables the visualization of the brain response during anesthesia and may prevent unnecessary anesthetic consumption.

METHODS

This retrospective study included 140 adult patients undergoing elective craniotomy who received total intravenous anesthesia using a combination of propofol and dexmedetomidine infusions. Patients were equally matched to the spectrogram group (maintaining the robust EEG alpha power during surgery) or the index group (maintaining the BIS score between 40 and 60 during surgery) based on the propensity score of age and surgical type. The primary outcome was the propofol dose. Secondary outcome was the postoperative neurological profile.

RESULTS

Patients in the spectrogram group received significantly less propofol (1585 ± 581 vs. 2314 ± 810 mg, P < 0.001). Fewer patients in the spectrogram group exhibited delayed emergence (1.4% vs. 11.4%, P = 0.033). The postoperative delirium profile was similar between the groups (profile P = 0.227). Patients in the spectrogram group exhibited better in-hospital Barthel's index scores changes (admission state: 83.6 ± 27.6 vs. 91.6 ± 17.1; discharge state: 86.4 ± 24.3 vs. 85.1 ± 21.5; group-time interaction P = 0.008). However, the incidence of postoperative neurological complications was similar between the groups.

CONCLUSIONS

EEG spectrogram-guided anesthesia prevents unnecessary anesthetic consumption during elective craniotomy. This may also prevent delayed emergence and improve postoperative Barthel index scores.

Monitoring nociception and awareness during palliative sedation: A systematic review

BACKGROUND

Providing unawareness and pain relief are core elements of palliative sedation. In addition to clinical scales, nociception and electroencephalogram-based depth of sedation monitoring are used to assess the level of consciousness and analgesia during sedation in intensive care units and during procedures.

AIM

To determine whether reported devices impact the outcomes of palliative sedation.

DESIGN

Systematic review and narrative synthesis of research published between January 2000 and December 2020.

DATA SOURCES

Embase, Google Scholar, PubMed, CENTRAL, and the Cochrane Library. All reports describing the use of any monitoring device to assess the level of consciousness or analgesia during palliative sedation were screened for inclusion. Data concerning safety and efficacy were extracted. Patient comfort was the primary outcome of interest. Articles reporting sedation but that did not meet guidelines of the European Association for Palliative Care were excluded.

RESULTS

Six reports of five studies were identified. Four of these were case series and two were case reports. Together, these six reports involved a total of 67 sedated adults. Methodological quality was assessed fair to good. Medication regimens were adjusted to bispectral index monitoring values in two studies, which found poor correlation between monitoring values and observational scores. In another study, high nociception index values, representing absence of pain, were used to detect opioid overdosing. Relatives and caregivers found the procedures feasible and acceptable.

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.

[Evaluation of Bispectral Index time delay in response to anesthesia induction: an observational study]

BACKGROUND AND OBJECTIVES

According to the manufacturer, the Bispectral Index (BIS) has a processing time delay of 5-10s. Studies addressing this have suggested longer delays. We evaluated the time delay in the Bispectral Index response.

METHODS

Based on clinical data from 45 patients, using the difference between the predicted and the real BIS, calculated during a fixed 3minutes period after the moment the Bispectral Index dropped below 80 during the induction of general anesthesia with propofol and remifentanil.

RESULTS

The difference between the predicted and the real BIS was in average 30.09±18.73s.

CONCLUSION

Our results may be another indication that the delay in BIS processing may be much longer than stated by the manufacture, a fact with clinical implications.

Propofol-sparing effect of different concentrations of dexmedetomidine : Comparison of gender differences

Background

The pharmacodynamics of propofol are closely linked to gender. Dexmedetomidine can decrease propofol needs during propofol anesthesia. The aim of this study was to compare the gender differences on the calculated effect site median effective concentration (EC₅₀) of propofol for loss of consciousness (LOC) after pretreatment with different concentrations of dexmedetomidine.

Methods

In this study 60 male and 60 female patients were randomly allocated to receive dexmedetomidine at target plasma concentrations of 0.0 ng/ml (0.0 group), 0.4 ng/ml (0.4 group), 0.6 ng/ml (0.6 group) and 0.8 ng/ml (0.8 group). Propofol was administered after dexmedetomidine had been intravenously infused for 15 min. The propofol infusion was targeted to provide an initial effect-site concentration of 1.0 μg/ml, followed by increments by 0.2 μg/ml when the effect-site concentration and target concentration of propofol were in equilibrium until LOC was established, where LOC was defined by the observer’s assessment of alertness/sedation scale (OAA/S) score < 2.

Results

The calculated effect-site EC₅₀ of propofol LOC was higher in males than in females in the 0.0, 0.4, 0.6, and 0.8 groups (2.43 vs. 2.17, 1.99 vs. 1.82, 1.72 vs. 1.56 and 1.50 vs. 1.32 μg/ml, respectively, all p < 0.05). The hypnotic interaction between dexmedetomidine and propofol could be described with an additive model of pharmacodynamic interaction.

Conclusion

Gender significantly influenced the calculated effect-site EC₅₀ of propofol for LOC after pretreatment with different concentrations of intravenous dexmedetomidine. It was concluded that an additive interaction could describe the results seen. Thus, gender has to be considered when these drugs are co-administered.

[Anesthetic requirements measured by bilateral bispectral analysis and femoral blockade in total knee arthroplasty]

BACKGROUND AND OBJECTIVES

A continuous peripheral nerve blockade has proved benefits on reducing postoperative morphine consumption; the combination of a femoral blockade and general anesthesia on reducing intraoperative anesthetic requirements has not been studied. The objective of this study was to determine the relevance of timing in the performance of femoral block to intraoperative anesthetic requirements during general anesthesia for total knee arthroplasty.

METHODS

A single-center, prospective cohort study on patients scheduled for total knee arthroplasty, were sequentially allocated to receive 20mL of 2% mepivacaine throughout a femoral catheter, prior to anesthesia induction (Preoperative) or when skin closure started (Postoperative). An algorithm based on bispectral values guided intraoperative anesthetic management. Postoperative analgesia was done with an elastomeric pump of levobupivacaine 0.125% connected to the femoral catheter and complemented with morphine patient control analgesia for 48hours. The Kruskall Wallis and the chi-square tests were used to compare variables. Statistical significance was set at p<0.05.

RESULTS

There were 94 patients, 47 preoperative and 47 postoperative. Lower fentanyl and sevoflurane were needed intraoperatively in the Preoperative group; median values and range: 250 (100-600) vs 450 (200-600)μg and 21 (12-48) vs 32 (18-67)mL p=0.001, respectively. There were no differences in the median verbal numeric rating scale values 4 (0-10) vs 3 (0-10); and in median morphine consumption 9 (2-73) vs 8 (0-63)mg postoperatively.

CONCLUSIONS

A preoperative femoral blockade is useful in decreasing anesthetic requirements in total knee arthroplasty surgery but no added effect in the postoperative analgesic control.

Postoperative surveillance in neurosurgical patients - usefulness of neurological assessment scores and bispectral index

BACKGROUND AND OBJECTIVES

We examined the additive effect of the Ramsay scale, Canadian Neurological Scale (CNS), Nursing Delirium Screening Scale (Nu-DESC), and Bispectral Index (BIS) to see whether along with the assessment of pupils and Glasgow Coma Scale (GCS) it improved early detection of postoperative neurological complications.

METHODS

We designed a prospective observational study of two elective neurosurgery groups of patients: craniotomies (CG) and non-craniotomies (NCG). We analyze the concordance and the odds ratio (OR) of altered neurological scales and BIS in the Post-Anesthesia Care Unit (PACU) for postoperative neurological complications. We compared the isolated assessment of pupils and GCS (pupils-GCS) with all the neurologic assessment scales and BIS (scales-BIS).

RESULTS

In the CG (n=70), 16 patients (22.9%) had neurological complications in PACU. The scales-BIS registered more alterations than the pupils-GCS (31.4% vs. 20%; p<0.001), were more sensitive (94% vs. 50%) and allowed a more precise estimate for neurological complications in PACU (p=0.002; OR=7.15, 95% CI=2.1-24.7 vs. p=0.002; OR=9.5, 95% CI=2.3-39.4). In the NCG (n=46), there were no neurological complications in PACU. The scales-BIS showed alterations in 18 cases (39.1%) versus 1 (2.2%) with the pupils-GCS (p<0.001). Altered CNS on PACU admission increased the risk of neurological complications in the ward (p=0.048; OR=7.28, 95% CI=1.021-52.006).

CONCLUSIONS

Applied together, the assessment of pupils, GCS, Ramsay scale, CNS, Nu-DESC and BIS improved early detection of postoperative neurological complications in PACU after elective craniotomies.

Loading dose of Dexdor® and optimal sedation during oral and maxillofacial ambulatory surgery procedures: An observational study

INTRODUCTION

Dexdor^® do not include the possibility of loading dose, which could increase time to achieve adequate sedation for ambulatory procedures. The objective of this study was to evaluate the effect of several loading dose of dexmedetomidine in the time to achieve and maintain an optimal level of sedation and its clinical hemodynamic repercussion.

MATERIAL AND METHODS

The IRB approved this observational study for patients that underwent oral and maxillofacial ambulatory surgery under dexmedetomidine at the University of Navarra Clinic from February 2013 to November 2014. According to the loading dose the patients were grouped into 3 categories:<0.5, 0.5, and>0.5μg/kg. Optimal level of sedation was defined as bispectral index<85. Data were analyzed using survival analysis techniques. Vasoactive drugs requirements was evaluated using exact logistic regression.

RESULTS

Eighty-one patients were evaluated. Hazard ratios for patients in 0.5 and >0.5μg/kg loading dose categories for achieving a bispectral index<85 were 1.5 (95% CI 0.9, 2.6) and 1.8 (95% CI 0.8, 3.9), respectively, compared with the lowest category. Five patients (6.2%) required atropine for bradycardia. Patients in the group>0.5μg/kg showed greater risk of requiring atropine compared with the group<0.5μg/kg (odds ratio 2.2; 95% CI 0.03, 183).

CONCLUSION

Loading dose of dexmedetomidine>0.5μg/kg appears minimize the time to achieve and maintain an optimal level of sedation during the first 60min of procedure. Further investigation to elucidate the association between loading dose of dexmedetomidine and subsequent atropine requirements may be warranted.

Effects of music on sedation depth and sedative use during pediatric dental procedures

STUDY OBJECTIVE

The study aimed to investigate the effects of listening to music or providing sound isolation on the depth of sedation and need for sedatives in pediatric dental patients.

DESIGN

Prospective, randomized, and controlled study.

SETTING

Tertiary, university hospital.

PATIENTS

In total, 180 pediatric patients, American Society of Anesthesiologists physical status I and II, who were scheduled for dental procedures of tooth extraction, filling, amputation, and root treatment.

INTERVENTIONS

Patients were categorized into 3 groups: music, isolation, and control. During the procedures, the patients in the music group listened to Vivaldi's The Four Seasons violin concertos by sound-isolating headphones, whereas the patients in the isolation group wore the headphones but did not listen to music. All patients were sedated by 0.1 mg/kg midazolam and 1 mg/kg propofol. During the procedure, an additional 0.5 mg/kg propofol was administered as required.

MEASUREMENTS AND MAIN RESULTS

Bispectral index was used for quantifying the depth of sedation, and total dosage of the propofol was used for sedative requirements. The patients' heart rates, oxygen saturations, and Observer's Assessment of Alertness and Sedation Scale and bispectral index scores, which were monitored during the operation, were similar among the groups. In terms of the amount of propofol used, the groups were similar. Prolonged postoperative recovery cases were found to be significantly frequent in the control group, according to the recovery duration measurements (P = .004).

CONCLUSIONS

Listening to music or providing sound isolation during pediatric dental interventions did not alter the sedation level, amount of medication, and hemodynamic variables significantly. This result might be due to the deep sedation levels reached during the procedures. However, listening to music and providing sound isolation might have contributed in shortening the postoperative recovery duration of the patients.

The effects of deep and light propofol anesthesia on stress response in patients undergoing open lung surgery: a randomized controlled trial

Background

This prospective, randomized controlled study was undertaken to compare stress hormone response to open thoracotomy for lung resection at different anesthetic depths, as determined by bispectral index (BIS) monitoring, in patients under propofol-remifentanil anesthesia.

Methods

Forty-eight adult patients scheduled for lung resection surgery using one-lung ventilation were randomly assigned to either a deep anesthesia group (BIS score of 40 ± 5, n = 24) or a light anesthesia group (BIS score of 60 ± 5, n = 24) by adjusting propofol infusion rates. Blood norepinephrine, epinephrine, adrenocorticotropic hormone, and cortisol levels were measured before the induction of anesthesia, at the end of surgery, and at 2 hours postoperatively. Blood glucose, hemodynamic, and oxygenation-ventilation variables, and postoperative outcomes were also measured.

Results

Norepinephrine and epinephrine levels remained unchanged over time in the deep group, but norepinephrine levels significantly increased in the light group at 2 h after surgery than at baseline (P = 0.007 and 0.004, respectively). Temporal changes in norepinephrine, but not in epinephrine, were significantly different between the two groups (P = 0.036). Plasma glucose levels in the light group increased with time and were significantly higher than in the deep group at the end of surgery (P = 0.002).

Conclusions

A deep level of anesthesia achieved using high propofol infusion rates during lung surgery provided lower perioperative norepinephrine and glucose responses than light level of anesthesia during the early postoperative period but failed to affect immediate postoperative outcomes.

Bispectral index as a possible early marker of cerebral hypoperfusion

We report a case of unexplained transient ventricular fibrillation in a child with ventricular septal defect (VSD) scheduled for VSD closure. The bispectral index (BIS) values dropped within 15s of transient cardiac arrest and it showed recovery within 15 s of restoration of circulation. Monitoring BIS during surgery, especially cardiac surgeries may help identify periods of cerebral ischemia early.

The optimal anesthetic depth for interventional neuroradiology: comparisons between light anesthesia and deep anesthesia

Background

This study was designed to determine the optimal anesthetic depth for the maintenance and recovery in interventional neuroradiology.

Methods

Eighty-eight patients undergoing interventional neuroradiology were randomly allocated to light anesthesia (n = 44) or deep anesthesia (n = 44) groups based on the value of the bispectral index (BIS). Anesthesia was induced with propofol, alfentanil, and rocuronium and maintained with 1-3% sevoflurane. The concentration of sevoflurane was titrated to maintain BIS at 40-49 (deep anesthesia group) or 50-59 (light anesthesia group). Phenylephrine was used to maintain the mean arterial pressure within 20% of preinduction values. Recovery times were recorded.

Results

The light anesthesia group had a more rapid recovery to spontaneous ventilation, eye opening, extubation, and orientation (4.1 ± 2.3 vs. 5.3 ± 1.8 min, 6.9 ± 3.2 min vs. 9.1 ± 3.2 min, 8.2 ± 3.1 min vs. 10.7 ± 3.3 min, 10.0 ± 3.9 min vs. 12.9 ± 5.5 min, all P < 0.01) compared to the deep anesthesia group. The use of phenylephrine was significantly increased in the deep anesthesia group (768 ± 184 vs. 320 ± 82 µg, P < 0.01). More patients moved during the procedure in the light anesthesia group (6/44 [14%] vs. 0/44 [0%], P = 0.026).

Conclusions

BIS values between 50 and 59 for interventional neuroradiology were associated with a more rapid recovery and favorable hemodynamic response, but also with more patient movement. We suggest that maintaining BIS values between 40 and 49 is preferable for the prevention of patient movement during anesthesia for interventional neuroradiology.

Comparison of sevoflurane concentration for insertion of proseal laryngeal mask airway and tracheal intubation in children (correlation with BIS)

BACKGROUND

Sevoflurane is an inhalational agent of choice in paediatric anaesthesia. For management of airways in children a suitable alternative to ETT is a paediatric proseal laryngeal mask airway (benchmark second generation SAD). Various studies have shown that less sevoflurane concentration is required for LMA insertion in comparison to TI. BIS is a useful monitor of depth of anaesthesia.

AIMS

To compare concentration of sevoflurane (end tidal and MAC value) required for proseal laryngeal mask airway insertion and tracheal intubation in correlation with BIS index.

METHOD

The prospective randomised single blind study was done in children between 2 and 9 years of ASA I and II and they were randomly allocated to Group P (proseal laryngeal mask airway insertion) and Group TI (tracheal intubation). No sedative premedication was given. Induction was done with 8% sevoflurane and then predetermined concentration was maintained for 10 min. Airway was secured either by proseal laryngeal mask airway or endotracheal tube without using muscle relaxant. End tidal sevoflurane concentration, MAC, BIS, and other vital parameters were monitored every minute till insertion of an airway device. Insertion conditions were observed. Statistical analysis was done by ANOVA and Students t test.

RESULTS

Difference between ETLMI (2.49 ± 0.44) and ETTI (2.81 ± 0.65) as well as MACLMI (1.67 ± 0.13) and MACTI (1.77 ± 0.43) was statistically very significant, while BISLMI (49.05 ± 10.76) and BISTI (41.25 ± 3.25) was significant. Insertion conditions were comparable in both the groups.

CONCLUSION

We can conclude that in children airway can be secured safely with proseal laryngeal mask airway using less sevoflurane concentration in comparison to tracheal intubation and this was supported by BIS index.

The effect of dexmedetomidine infusion on propofol requirement for maintenance of optimum depth of anaesthesia during elective spine surgery

Background:

Maintenance of adequate depth of anaesthesia in spine surgery is vital to prevent awareness, to reduce stress response and possible autonomic instability frequently associated with spine surgery. Dexmedetomidine, a α₂-adrenoceptor agonist with analgesic and sedative adjuvant property has been found to reduce dose requirement of multiple anaesthetic agents both for induction and during the maintenance of anaesthesia.

Aim:

The aim of this study is to observe the effect of dexmedetomidine, on the requirement of propofol for induction and maintenance of adequate depth of anaesthesia during spine surgery.

Methods:

It was a prospective, randomised, double-blinded, parallel group, placebo controlled and open-lebel study in tertiary care hospital. A total of 70 patients aged 20-60 years, American Society of Anaesthesiologists GradeI and II, scheduled for elective spine surgery were randomly allocated into two groups. Each patient of Group D (n=35) received an initial loading dose of dexmedetomidine at 1 μg/kg over 10 min, started 15 min before induction of anaesthesia followed by an infusion at a rate of 0.2 μg/kg/h. Patients of Group P (n=35) received the same volume of 0.9% normal saline solution as placebo. Requirement of propofol at induction and during maintenance was calculated maintaining bispectral index between 40 and 60. P<0.05 was considered to be statistically significant.

Results:

Mean requirement of propofol was found to be lessened by 48.08% and 61.87% for induction and maintenance of anaesthesia respectively while using dexmedetomidine.

Conclusion:

Administration of dexmedetomidine significantly reduces the requirement of propofol while maintaining desired depth of anaesthesia without any significant complication.

Interruption of bispectral index monitoring by nerve integrity monitoring during tympanoplasty -A case report-

We report that intraoperative NIM-2 monitoring devices can interfere with bispectral index monitoring. A 45-year-old male with chronic otits media underwent tympanolasty under general anesthesia with NIM-2 monitoring and bispectral index monitoring at our institution. And then, bispectral index monitoring was severely interrupted by facial nerve monitoring.