Correlation of bispectral index and Richmond agitation sedation scale for evaluating sedation depth: a retrospective study

Correlating the Depth of Sedation Between the Ramsay Sedation Scale and Bispectral Index Using Either Intravenous Midazolam or Intravenous Propofol in Elderly Patients Under Spinal Anaesthesia

BACKGROUND

Supplementation of spinal anaesthesia with sedatives or anxiolytics has emerged as a standard protocol to alleviate patients' anxiety and to produce amnesia during the surgical procedure. Thus, judicious use of sedation can make surgeries under spinal anaesthesia more comfortable and acceptable for the elderly patient, the surgeon, and the anaesthesiologist. However, over-sedation may jeopardise the safety of the patient. Appropriate sedation helps reduce physiological stress, which leads to a better result. Therefore, monitoring the depth of sedation becomes essential. The Ramsay sedation scale (RSS) and bispectral index (BIS) both are used widely to assess the depth of sedation.

OBJECTIVES

The primary objective of the study was to assess and correlate the depth of sedation between the BIS and RSS in elderly patients using midazolam and propofol under spinal anaesthesia. The secondary objectives were to observe any difference in the commencement of sedation between the two groups and to observe haemodynamic changes between the two groups.

METHODS

A total of 60 elderly patients undergoing urological procedures under spinal anaesthesia were randomly assigned to receive either midazolam (Group A, n=30) or propofol (Group B, n=30) for sedation. In Group A, patients were given an initial bolus of midazolam 0.03 mg/kg and a maintenance incremental bolus of 0.01 mg/kg up to a maximum of 2.5 mg in 10-minute intervals. Group B used propofol with an initial bolus dose of 0.5 mg/kg over two minutes and a maintenance bolus of 10-20 mg as required for the maintenance of sedation depth. Sedation was titrated to achieve a BIS score of 70-80 and an RSS score of 3-4. Heart rate, non-invasive systolic, diastolic, mean arterial blood pressure, oxygen saturation (SPO2), and the correlation coefficient between the BIS and RSS were measured at 0 (baseline), 5, 10, 20, 30, 40, 50, and 60 minutes of interval.

RESULTS

The correlation coefficient between the BIS and RSS scores in Group A at various time intervals indicate a strong correlation coefficient of -0.76 at five minutes, -0.64 at 20 minutes, -0.78 at 30 minutes, -0.56 at 40 minutes, and -0.39 at 50 minutes. In Group B, the correlation coefficient between the BIS and RSS scores at various time intervals indicate a strong correlation coefficient of -0.75 at five minutes, -0.76 at 20 minutes,-0.64 at 30 minutes, -0.89 at 40 minutes, and -0.46 at 50 minutes of interval. We also observed that the BIS drops to a lower level in patients receiving propofol (Group B) with a significant difference depicting early onset of sedation with propofol. In Group B, HR and MAP were significantly less than those of Group A. There was no significant difference in terms of mean age, sex, and body weight in the patients of both groups.

CONCLUSION

The BIS and RSS scores indicate a strong correlation with a magnitude of 70%-80%, but more in Group B (propofol) than Group A (midazolam). Therefore, the characteristics of each sedative drug can influence the level of sedation during spinal anaesthesia. Clinicians should use a combination of BIS values and other objective sedative methods to determine the degree of sedation, rather than relying exclusively on BIS values.

The utility of bispectral index monitoring in flexible bronchoscopy: A single-center, retrospective observational study

BACKGROUND

The desired depth of sedation during flexible bronchoscopy is one in which verbal contact is possible whenever necessary. Although it is common that the depth of sedation is assessed by validated instruments such as the modified observer's assessment of alertness and sedation (MOAA/S) score, the repeated stimulation associated with the assessment can affect the sedation. The bispectral index (BIS) has been widely used for general anesthesia due to its objective and noninvasive nature. However, the utility of BIS monitoring and a target BIS value for use during bronchoscopy have not been fully elucidated.

METHODS

We performed a retrospective observational study to assess the utility of the BIS value for monitoring conscious sedation during bronchoscopy at Kobe University Hospital from August 2020 to April 2021.

RESULTS

Eighteen patients underwent bronchoscopy with BIS monitoring. The BIS value significantly correlated with the MOAA/S score (r = 0.2, p < 0.01), and the correlation was stronger in sufficiently sedated patients (r = 0.486, p < 0.01). The lowest MOAA/S score during the procedure was highly correlated with the BIS value (r = 0.625, p < 0.01). The BIS monitoring seemed to be more sensitive to changes in the sedation level than the MOAA/S score, heart rate and mean arterial pressure. The median BIS value at an MOAA/S score of 3-4, the desired depth of sedation, was 82.0.

CONCLUSIONS

BIS value is useful for monitoring sedation during bronchoscopy. This study suggests that a BIS value of 82 reflects an adequate level of sedation.

Comparison of the performance of phase lag entropy and bispectral index for monitoring the depth of sedation under dexmedetomidine sedation: A prospective, observational, and non-inferiority trial

STUDY OBJECTIVE

Although the performance of phase lag entropy (PLE), a new depth-of-sedation monitor based on the diversity of temporal patterns in the phase relationships in electroencephalogram (EEG) data, during propofol sedation has been proven through several studies, since different sedatives have different effects on EEG, we aimed to evaluate the performance of the PLE in comparison with the bispectral index (BIS) during dexmedetomidine sedation.

DESIGN

A prospective, observational, and non-inferiority trial.

SETTING

Tertiary university hospital operating room.

PATIENTS

Forty-two patients aged 20-80 years who were scheduled to undergo elective surgery under spinal anesthesia and had American Society of Anesthesiologists (ASA) physical status I to III were enrolled in this study.

INTERVENTIONS

Dexmedetomidine was administered with a loading dose of 0.5-1 μg/kg for 10 min, followed by a maintenance dose of 0.3-0.6 μg/kg/h.

MEASUREMENTS

The depth of sedation was assessed using the modified observer's assessment of alertness/sedation (MOAA/S) scale; the data for PLE and BIS were collected; and vital signs, including blood pressure, heart rate, EKG, and pulse oximetry, were evaluated.

MAIN RESULTS

215,082 data points for the MOAA/S score and PLE and BIS values were analyzed. The baseline variabilities of PLE and BIS were 4.53% and 7.02%, respectively. The Spearman correlation coefficients of the MOAA/S score with PLE and BIS were 0.599 and 0.566, respectively. The prediction probabilities of the MOAA/S score with PLE and BIS were 0.647 and 0.636, respectively. When the MOAA/S score was 3 points, the mean (SD) values of PLE and BIS were 68.35 (15.68) and 75.85 (9.81), respectively, However, the mean (SD) values of PLE and BIS for an MOAA/S score of 1 point were 56.08 (12.49) and 68.29 (12.65), respectively.

CONCLUSIONS

PLE shows potential as a hypnotic depth indicator during dexmedetomidine sedation, and its performance was not inferior to that of BIS.

Verification of the performance of the Bispectral Index as a hypnotic depth indicator during dexmedetomidine sedation

Background

Differences in the effects of propofol and dexmedetomidine sedation on electroencephalogram patterns have been reported previously. However, the reliability of the Bispectral Index (BIS) value for assessing the sedation caused by dexmedetomidine remains debatable. The purpose of this study is to evaluate the correlation between the BIS value and the Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) scale in patients sedated with dexmedetomidine.

Methods

Forty-two patients aged 20–80 years, who were scheduled for surgery under spinal anesthesia were enrolled. Spinal anesthesia was performed using 0.5% bupivacaine, which was followed by dexmedetomidine infusion (loading dose, 0.5–1 μg/kg for 10 min; maintenance dose, 0.3–0.6 μg/kg/h). The MOAA/S score was used to evaluate the level of sedation.

Results

A total of 215082 MOAA/S scores and BIS data pairs were analyzed. The baseline variability of the BIS value was 7.024%, and BIS value decreased, as the MOAA/S scored decreased. The correlation coefficient and prediction probability between the two measurements were 0.566 (P < 0.0001) and 0.636, respectively. The mean ± standard deviation values of the BIS were 87.22 ± 7.06, 75.85 ± 9.81, and 68.29 ± 12.65 when the MOAA/S scores were 5, 3, and 1, respectively. Furthermore, the cut-off BIS values in the receiver operating characteristic analysis at MOAA/S scores of 5, 3, and 1 were 82, 79, and 73, respectively.

Conclusions

The BIS values were significantly correlated with the MOAA/S scores. Thus, the BIS along with the clinical sedation scale might prove useful in assessing the hypnotic depth of a patient during sedation with dexmedetomidine.

Dexmedetomidine combined with midazolam infusion guided by bispectral index during bronchoscopy

BACKGROUND

Conscious sedation guided by bispectral index (BIS) during bronchoscopy has been proved to be a feasible approach. This study aimed to investigate the safety and efficacy of dexmedetomidine combined with midazolam for undergoing conscious sedation during bronchoscopy.

METHODS

The trial was registered prior to patient enrollment at the Chinese Clinical Trial Registry. Patients were randomized into DEX group (dexmedetomidine combined with midazolam) and FEN group (fentanyl combined with midazolam). Bronchoscopy was performed under awake sedation titrated to a BIS level of 60-80. The primary endpoint was the incidence of hypoxia, the secondary endpoint was the incidence of bradycardia and hypotension, effect of sedation including satisfaction degree (VAS) of the operators and patients and patients' willingness to undergo bronchoscopy again.

RESULTS

A total of 222 cases in DEX group and 211 cases in FEN group completed the study. The incidence of hypoxia and tachycardia in DEX group was lower than that in FEN group (8.1% vs 14.7%, 10.4% vs 19.0%, p < 0.05), and the incidence of hypotension and bradycardia in DEX group was higher than that in FEN group (6.8% vs 0, 15.3% vs 8.1%, p < 0.05). Midazolam dosage was significantly lower in the DEX group than in the FEN group, and the duration of surgery was significantly longer in the DEX group. The differences in intraoperative discomfort of VAS score, satisfaction VAS score, and willingness rate to undergo bronchoscopy again were not statistically significant between the two groups. In addition, the proportion of "procedural interference by patient movement" in DEX group was higher than that in FEN group.

CONCLUSIONS

The conscious sedation regimen of dexmedetomidine combined with midazolam monitored by BIS is considered to be safe and effective during bronchoscopy. The occurrence of hypoxia and tachycardia was less, and the fluctuation of blood pressure and heart rate was mild, but the proportion of bradycardia in dexmedetomidine group was higher than that in fentanyl combined with midazolam group.

Volatile Sedation for Acute Respiratory Distress Syndrome Patients on Venovenous Extracorporeal Membrane Oxygenation and Ultraprotective Ventilation

Supplemental Digital Content is available in the text.

Patients on extracorporeal support for severe acute respiratory distress syndrome may require a prolonged period of deep sedation. In these patients, volatile sedation may represent a valid alternative to IV drugs. The aim of our study was to describe the feasibility of volatile sedation in a large cohort of acute respiratory distress syndrome patients undergoing venovenous extracorporeal membrane oxygenation and ultraprotective ventilation.

Ketamine in acute phase of severe traumatic brain injury "an old drug for new uses?"

Maintaining an adequate level of sedation and analgesia plays a key role in the management of traumatic brain injury (TBI). To date, it is unclear which drug or combination of drugs is most effective in achieving these goals. Ketamine is an agent with attractive pharmacological and pharmacokinetics characteristics. Current evidence shows that ketamine does not increase and may instead decrease intracranial pressure, and its safety profile makes it a reliable tool in the prehospital environment. In this point of view, we discuss different aspects of the use of ketamine in the acute phase of TBI, with its potential benefits and pitfalls.

Does Exposure to General Anesthesia Increase Risk of ADHD for Children Before Age of Three?

Objective: The objective of the study was to evaluate the relationship between frequency of exposure to general anesthesia before the age of 3 and subsequent risk of diagnosis for attention-deficit hyperactivity disorder (ADHD). Method: We searched PubMed, Embase, Web of Science, and Cochrane Library database for eligible inclusion in the meta-analysis. The indicated outcomes were extracted from the included studies, and the combined effects were calculated using the RevMan software 5.3. Results: Compared with no exposure to general anesthesia, single exposure to general anesthesia did not increase the risk of ADHD for children before the age of 3 [hazard ratio (HR): 1.14, 95%; confidence intervals (CI): 0.97-1.35; p = 0.11; I ² = 0%], while multiple exposures to general anesthesia did increase the risk of ADHD (HR: 1.83; 95% CIs: 1.00-3.32; p = 0.05; I ² = 81%). Conclusion: Multiple, but not single, exposures to general anesthesia in children before age of 3 increased the risk of ADHD.

Can Bispectral Index Monitoring (EEG) be an Early Predictor of Respiratory Depression under Deep Sedation during Endoscopic Retrograde Cholangiopancreatography?

Objectives:

The more often the endoscopy sedation is performed, the more the risk of adverse events, and therefore, advanced monitoring becomes more and more essential in endoscopy units. The present study aims to evaluate whether the Bispectral Index (BIS) monitoring is an early predictor of respiratory depression and to determine the compliance between commonly used clinical sedation score.

Methods:

This study was approved by the ethics committee. The sample consisted of 60 patients aged 18 to 50 years with an American Society of Anesthesiologists (ASA) physical status of I scheduled for endoscopic retrograde cholangiopancreatography (ERCP). All patients received propofol mediated sedation. Ramsay sedation score (RSS) was used as a clinical sedation score to assess the depth of sedation. Participants were attached to a BIS monitor. Perioperative hemodynamics, BIS values, the mean dose of propofol, procedure duration, apnea, frequency of oxygen desaturation and airway-related interventions, as well as demographic parameters, were recorded. BIS scores were blinded to RSS data.

Results:

The study sample consisted of 60 patients (36 females) aged 18 to 50 years (mean: 36.10±8.02). The mean procedure time and the dose of propofol were 32.70±1.79 min and 287.17±59.66 mg, respectively. The cut-off values for respiratory depression were as follows. At the 15th min of measurement, the BIS score of 60 had 96.2% sensitivity and 42.9% specificity. At the 20th min of measurement, the BIS score of 59.50 had 98.2% sensitivity and 100.0% specificity. At the 25th min of measurement, the BIS score of 59.00 had 98.3% sensitivity and 50.0% specificity. Regression analysis showed that the mean BIS score (p=0.000, 95%CI-0.110-0.043) increased by 0.076 with a unit increase in the RSS.

Conclusion:

BIS was highly correlated with RSS, and therefore, can be used to avoid respiratory depression during sedation.

Efficacy of the bispectral index and Observer's Assessment of Alertness/Sedation Scale in monitoring sedation during spinal anesthesia: A randomized clinical trial

OBJECTIVE

The bispectral index (BIS) has been used to monitor sedation during spinal anesthesia. We evaluated the correlation between BIS and the Observer's Assessment of Alertness/Sedation Scale (OAA/S) in patients sedated with dexmedetomidine, propofol, or midazolam.

METHODS

This prospective, randomized study included 46 patients scheduled for knee arthroplasty under spinal anesthesia with sedation. The patients were randomized to receive sedation with dexmedetomidine (n = 15), propofol (n = 15), or midazolam (n = 16). Correlation between BIS and OAA/S was assessed during sedation in the three groups.

RESULTS

A linear correlation was observed between BIS and OAA/S, and there was no significant difference in BIS score between the groups during mild to moderate sedation status (OAA/S 3-5). During deep sedation (OAA/S 1-2), the BIS score in the midazolam group was significantly higher than that in the propofol and dexmedetomidine groups (74.4 ± 11.9 vs 67.7 ±  9.5 vs 62.6 ± 12.2).

CONCLUSIONS

BIS values differed at the same level of sedation between different sedative agents. Objective sedation scores should therefore be used in combination with BIS values for the assessment of sedation levels during spinal anesthesia.

Effects of continuous positive airway pressure in patients at high risk of obstructive sleep apnea during propofol sedation after spinal anesthesia

In patients with obstructive sleep apnea, short-term use of a continuous positive airway pressure mask improves oxygenation, decreases the apnea-hypopnea index, and reduces hemodynamic instability. In this study, we investigated the effects of use of a continuous positive airway pressure mask in patients at high risk of obstructive sleep apnea during propofol sedation after spinal anesthesia. Forty patients who underwent propofol sedation after spinal anesthesia for transurethral bladder or prostate resection with a STOP-Bang score of 3 or more were enrolled in this study. Patients were randomly divided into two groups: a simple oxygen mask group (n = 20) and a continuous positive airway pressure mask group (n = 20). After spinal anesthesia, propofol was injected at a target concentration of 1.3 mcg/ml via a target concentration control injector. ApneaLink™ was applied to all patients. Patients in the simple oxygen mask group were administered oxygen at a rate of 6 L/min through a simple facial mask. Patients in the CPAP mask group were connected to a pressurizer, and oxygen (6 L/min, 5-15 cm H₂O) was administered. Blood pressure, heart rate, respiratory rate, and oxygen saturation were recorded preoperatively, after spinal anesthesia, and every 5 min after the injection of propofol to observe hemodynamic changes. Apnea-hypopnea index was estimated using ApneaLink™. There were no significant differences in hemodynamic changes between the two groups. Apnea-hypopnea index was significantly reduced in the continuous positive airway pressure mask group compared to the simple facial mask group. Application of a continuous positive airway pressure mask in a patient at high risk of obstructive sleep apnea can lower the incidence of obstructive sleep apnea during sedation without a significant effect on hemodynamic stability.