Comparison of the Conox (qCON) and Sedline (PSI) depth of anaesthesia indices to predict the hypnotic effect during desflurane general anaesthesia with ketamine

The nociceptive response during adult cardiac surgery measured by the qNOX index: A feasibility study

BACKGROUND

Monitoring nociception during general anaesthesia remains a substantial challenge. The Conox monitor uses two EEG indices, the qCon and the qNox. The qNox refers to the probability that a nociceptive stimulation triggers a movement of the patient and the response probability of reaction to nociceptive stimulation. We decided to test the feasibility of monitoring the qNOX index during adult cardiac surgery and to investigate whether this index correlates with hemodynamic and hormonal signs of nociceptive stimulation.

METHOD

We enrolled 19 patients undergoing elective cardiac surgery. These were randomised to 2 groups receiving different doses of sufentanil via target controlled infusion: group A (n=9) 0.25 ng/mL and group B (n=10) 0.75 ng/mL. All patients were maintained at the same depth of anaesthesia. We recorded the Conox monitor indices (qNOX, qCON, electromyographic), hemodynamic variables and plasmatic levels of cortisol and noradrenaline.

RESULTS

There was significantly higher blood pressure (P=0.013) and plasmatic cortisol (P=0.003) in group A and a significant increase in plasmatic noradrenaline with increasing intensity of surgical stimulation in both groups: A (P=0.001), B (P=0.008). We found no significant corresponding changes in the qNOX index. There was a positive correlation between qNOX and hemodynamic signs of stimulation (P=0.012) and between the qNOX and EMG indices (P=0.013) after endotracheal intubation, but not later after EMG index dropped.

CONCLUSION

Our results do not support the assumption that signs of nociceptive stimulation during adult cardiac surgery will be reflected by the qNOX index. This may be related to compounding of qNOX processing and use of muscle relaxants. Further investigation on this field is needed.

[Processed EEG for personalized dosing of anesthetics during general anesthesia]

Electroencephalogram (EEG)-guided anesthesia is indispensable in modern operating rooms and has become established as the standard form of monitoring. Many anesthesiologists rely on processed EEG indices in the hope of averting anesthesia-related complications, such as intraoperative awareness, postoperative delirium and other cognitive complications in their patients. This educational review aims to provide information on the five most prevalent monitors used to guide depth of sedation during general anesthesia. This article elucidates the principles underpinning the application of these monitors where known, which are generally based on power in various EEG frequency bands and on the burst suppression pattern. Convinced that EEG-guided anesthesia has the potential of benefitting many surgical patients, it is felt that many basic principles and shortcomings of processed EEG indices need to be better understood in the clinical practice. After discussing the different monitors and clinically relevant data from the literature, the article gives a short practical guidance on how to critically interpret processed EEG information and troubleshooting of confounded indices in the context of clinical situations.

Intraoperative difficulty in cardiorespiratory management during anesthesia for retroperitoneal paraganglioma resection

We report the anesthetic management of a case of paraganglioma, which was challenging because of intraoperative circulatory changes and difficult ventilatory management. A 52-year-old man with a history of chronic obstructive pulmonary disease was scheduled for paraganglioma resection under general anesthesia combined with epidural anesthesia. Since a marked increase in blood pressure was observed immediately after administration of rocuronium, antihypertensive agents were administered as necessary. The ventilatory settings were initially adjusted to deliver a tidal volume of 7 mL/kg, and the drive pressure was maintained at 13 cm H₂O or less. However, despite increasing the minute volume, PETCO₂ increased to 60 mmHg and PaCO₂ to 76 mmHg before tumor removal. Blood pressure decreased immediately after tumor removal, and PETCO₂ and PaCO₂ gradually returned to normal. We speculated that the increases in PETCO₂ and PaCO₂ might have been due to both an increase in endogenous catecholamine secretion as well as chronic obstructive pulmonary disease. It is important to preoperatively evaluate the functionality of the tumor and to anticipate perioperative cardiorespiratory instability in the management of paragangliomas.

Effects of intra-operative administration of subanesthetic s-ketamine on emergence from sevoflurane anesthesia: a randomized double-blind placebo-controlled study

BACKGROUND

Ketamine is administered in the perioperative period for its benefits in analgesia, anti-agitation and anti-depression when administered at a small dose. However, it is not clear whether the intra-operative administration of ketamine would affect emergence under sevoflurane anesthesia. To investigate this effect, we designed this trial.

METHODS

In this randomized, double-blind, placebo-controlled study, we enrolled 44 female patients aged 18-60 who were scheduled to elective laparoscopic gynecological surgeries. All patients were randomly assigned to saline or s-ketamine group. In s-ketamine group, patients received 0.125 mg/kg s-ketamine 30 min after the start of surgery. In saline group, patients were administered the same volume of saline. Sevoflurane and remifentanil were used to maintain general anesthesia. The primary outcome was emergence time. We also assessed postoperative agitation, cognitive function, and delirium. In addition, we collected and analyzed prefrontal electroencephalogram (EEG) during and after general anesthesia.

RESULTS

There were no significant differences in emergence time between s-ketamine group and saline group (10.80 ± 3.77 min vs. 10.00 ± 2.78 min, P = 0.457). Neither postoperative agitation (4 [3, 4] vs. 4 [3, 4], P = 0.835) nor cognitive function (25.84 ± 2.69 vs. 25.55 ± 2.19, P = 0.412) differed between groups. No postoperative delirium was observed in either group. Subanesthetic s-ketamine resulted in active EEG with decreased power of slow (-0.35 ± 1.13 dB vs. -1.63 ± 1.03 dB, P = 0.003), delta (-0.22 ± 1.11 dB vs. -1.32 ± 1.09 dB, P = 0.011) and alpha (-0.31 ± 0.71 dB vs. -1.71 ± 1.34 dB, P = 0.0003) waves and increased power of beta-gamma bands (-0.30 ± 0.89 dB vs. 4.20 ± 2.08 dB, P < 0.0001) during sevoflurane anesthesia, as well as an increased alpha peak frequency (-0.16 ± 0.48 Hz vs. 0.31 ± 0.73 Hz, P = 0.026). EEG patterns did not differ during the recovery period after emergence between groups.

CONCLUSION

Ketamine administered during sevoflurane anesthesia had no apparent influence on emergence time in young and middle-aged female patients undergoing laparoscopic surgery. Subanesthetic s-ketamine induced an active prefrontal EEG pattern during sevoflurane anesthesia but did not raise neurological side effects after surgery.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2100046479 (date: 16/05/2021).

Relationship between ANI and qNOX and between MAC and qCON during outpatient laparoscopic cholecystectomy using remifentanil and desflurane without muscle relaxants: a prospective observational preliminary study

This study was designed to investigate qCON and qNOX variations during outpatient laparoscopic cholecystectomy using remifentanil and desflurane without muscle relaxants and compare these indices with ANI and MAC. Adult patients undergoing outpatient laparoscopic cholecystectomy were included in this prospective observational study. Maintenance of anesthesia was performed using remifentanil targeted to ANI 50-80 and desflurane targeted to MAC 0.8-1.2 without muscle relaxants. The ANI, qCON and qNOX and desflurane MAC values were collected at different time-points and analyzed using repeated measures ANOVA. The relationship between ANI and qNOX and between qCON and MAC were analyzed by linear regression. The ANI was comprised between 50 and 80 during maintenance of anesthesia. Higher values of qNOX and qCON were observed at induction and extubation than during all other time-points where they were comprised between 40 and 60. A poor but significant negative linear relationship (r² = 0.07, p < 0.001) was observed between ANI and qNOX. There also was a negative linear relationship between qCON and MAC (r² = 0.48, p < 0.001) and between qNOX and remifentanil infusion rate (r² = 0.13, p < 0.001). The linear mixed-effect regression correlation (r²) was 0.65 for ANI-qNOX and 0.96 for qCON-MAC. The qCON and qNOX monitoring seems informative during general anesthesia using desflurane and remifentanil without muscle relaxants in patients undergoing ambulatory laparoscopic cholecystectomy. While qCON correlated with MAC, the correlation of overall qCON and ANI was poor but significant. Additionally, the qNOX weakly correlated with the remifentanil infusion rate. This observational study suggests that the proposed ranges of 40-60 for both indexes may correspond to adequate levels of hypnosis and analgesia during general anesthesia, although this should be confirmed by further research.

Electroencephalogram-Based Evaluation of Impaired Sedation in Patients with Moderate to Severe COVID-19 ARDS

The sedation management of patients with severe COVID-19 is challenging. Processed electroencephalography (pEEG) has already been used for sedation management before COVID-19 in critical care, but its applicability in COVID-19 has not yet been investigated. We performed this prospective observational study to evaluate whether the patient sedation index (PSI) obtained via pEEG may adequately reflect sedation in ventilated COVID-19 patients. Statistical analysis was performed by linear regression analysis with mixed effects. We included data from 49 consecutive patients. None of the patients received neuromuscular blocking agents by the time of the measurement. The mean value of the PSI was 20 (±23). The suppression rate was determined to be 14% (±24%). A deep sedation equivalent to the Richmond Agitation and Sedation Scale of −3 to −4 (correlation expected PSI 25−50) in bedside examination was noted in 79.4% of the recordings. Linear regression analysis revealed a significant correlation between the sedative dosages of propofol, midazolam, clonidine, and sufentanil (p < 0.01) and the sedation index. Our results showed a distinct discrepancy between the RASS and the determined PSI. However, it remains unclear to what extent any discrepancy is due to the electrophysiological effects of neuroinflammation in terms of pEEG alteration, to the misinterpretation of spinal or vegetative reflexes during bedside evaluation, or to other causes.

Comparison of Quantium Consciousness Index and Richmond Agitation Sedation Scale in Mechanically Ventilated Critically Ill Patients: An Observational Study

Background

The quantium consciousness index (qCON), an electroencephalography (EEG)-based modality, has no studies regarding intensive care unit (ICU) sedation, though very few studies describe its use for assessing depth of anesthesia in the operation theater. In this study, we evaluated qCON for assessing sedation compared with Richmond Agitation Sedation Scale (RASS) in patients on a mechanical ventilator in the ICU.

Materials and methods

Eighty-seven mechanically ventilated patients aged between 18 and 60 years were investigated over a 12-hour period. They were given a standardized dosage of sedation comprised of a bolus dose of propofol 0.5 mg/kg and fentanyl 1 µg/kg, and then infusions of propofol 2-5 mg/kg/hour and fentanyl 0.5-2 µg/kg/hour. These drug infusions were adjusted to achieve a RASS score between 0 and -3. Using the qCON monitor, the investigator recorded the qCON values and then assessed the RASS score.

Results

A total of 1,218 readings were obtained. After contrasting each qCON value correspondingly with time to each RASS value, we found their correlation to be statistically significant (ρ = 0.288, p <0.0001). With the help of receiver operating characteristic (ROC) curves, we were able to differentiate appropriate from inappropriate levels of sedation. A qCON value of 80 had a sensitivity of 72.67% and a specificity of 67.42% (AUC 0.738 with SE 0.021).

Conclusion

qCON can be used for assessing sedation levels in mechanically ventilated critically ill patients.

Clinical trial registration

CTRI/2019/07/020064.

How to cite this article

Harsha MS, Bhatia PK, Sharma A, Sethi P. Comparison of Quantium Consciousness Index and Richmond Agitation Sedation Scale in Mechanically Ventilated Critically Ill Patients: An Observational Study. Indian J Crit Care Med 2022;26(4):491-495.