Index of Consciousness monitoring may effectively predict and prevent circulatory stress induced by endotracheal intubation under general anesthesia: a prospective randomized controlled trial.
BMC anesthesiology
BACKGROUND:The primary objective of anesthesiologists during the induction of anaesthesia is to mitigate the operative stress response resulting from endotracheal intubation. In this prospective, randomized controlled trial, our aim was to assess the feasibility and efficacy of employing Index of Consciousness (IoC, IoC1 and IoC2) monitoring in predicting and mitigating circulatory stress induced by endotracheal intubation for laparoscopic cholecystectomy patients under general anesthesia (GA). METHODS:We enrolled one hundred and twenty patients scheduled for laparoscopic cholecystectomy under GA and randomly allocated them to two groups: IoC monitoring guidance (Group T, n = 60) and bispectral index (BIS) monitoring guidance (Group C, n = 60). The primary endpoints included the heart rate (HR) and mean arterial pressure (MAP) of the patients, as well as the rate of change (ROC) at specific time points during the endotracheal intubation period. Secondary outcomes encompassed the systemic vascular resistance index (SVRI), cardiac output index (CI), stroke volume index (SVI), ROC at specific time points, the incidence of adverse events (AEs), and the induction dosage of remifentanil and propofol during the endotracheal intubation period in both groups. RESULTS:The mean (SD) HR at 1 min after intubation under IoC monitoring guidance was significantly lower than that under BIS monitoring guidance (76 (16) beats/min vs. 82 (16) beats/min, P = 0.049, respectively). Similarly, the mean (SD) MAP at 1 min after intubation under IoC monitoring guidance was lower than that under BIS monitoring guidance (90 (20) mmHg vs. 98 (19) mmHg, P = 0.031, respectively). At each time point from 1 to 5 min after intubation, the number of cases with HR ROC of less than 10% in Group T was significantly higher than in Group C (P < 0.05). Furthermore, between 1 and 3 min and at 5 min post-intubation, the number of cases with HR ROC between 20 to 30% or 40% in Group T was significantly lower than that in Group C (P < 0.05). At 1 min post-intubation, the number of cases with MAP ROC of less than 10% in Group T was significantly higher than that in Group C (P < 0.05), and the number of cases with MAP ROC between 10 to 20% in Group T was significantly lower than that in Group C (P < 0.01). Patients in Group T exhibited superior hemodynamic stability during the peri-endotracheal intubation period compared to those in Group C. There were no significant differences in the frequencies of AEs between the two groups (P > 0.05). CONCLUSION:This promising monitoring technique has the potential to predict the circulatory stress response, thereby reducing the incidence of adverse reactions during the peri-endotracheal intubation period. This technology holds promise for optimizing anesthesia management. TRAIL REGISTRATION:Chinese Clinical Trail Registry Identifier: ChiCTR2300070237 (20/04/2022).
10.1186/s12871-024-02701-8
Effects on the bispectral index during medium-high dose fentanyl induction with or without propofol supplement.
Barr G,Anderson R E,Owall A,Jakobsson J G
Acta anaesthesiologica Scandinavica
BACKGROUND:The search for a drug-independent monitor to determine depth of anaesthesia and hypnosis continues. The bispectral analysis (BIS) of the EEG correlates well with the clinical dose-response of hypnotic drugs during induction, but the effect on BIS of an opiate induction, as for coronary bypass surgery, is not known. METHODS:Fourteen patients scheduled for elective coronary bypass surgery were studied. BIS was recorded during induction in 7 patients receiving 10 microg/kg fentanyl without any hypnotic agent and in 7 patients receiving 0.5 mg/kg propofol before the fentanyl dose. RESULTS:The effect of fentanyl was very variable both regarding BIS and clinical response. Five of the 7 patients that received only fentanyl lost their response to verbal command within 8 min. BIS values at loss of response varied between 45 and 94. One patient remained awake with BIS 43. All 7 patients receiving propofol before the fentanyl dose lost their response to verbal command within 5 min. BIS values at the time for loss of response varied between 78 and 98. CONCLUSION:Loss of response to verbal command when a medium-high dose of fentanyl is used for induction cannot be distinguished from wakefulness with adequate sensitivity by BIS. The current BIS algorithm seems not to accurately reflect the hypnotic effects of fentanyl.
Bispectral index and anaesthesia in the elderly.
Renna M,Venturi R
Minerva anestesiologica
BACKGROUND:Due to pharmacokinetic and pharmacodynamic reasons, the elderly are at particular risk of incurring unwanted side effects of drugs commonly used in anaesthesia. The bispectral index (BIS) is an EEG-derived value that measures the sedative component of the anaesthetic state. The BIS could be useful in guiding titration of anaesthetic drugs in the elderly. METHODS:A review of the published data was performed by the authors in order to assess the suitability of BIS technology application to the geriatric population. RESULTS:Age-related EEG differences exist in the normal population but they do not affect the BIS. The BIS correlates with depth of sedation independently of age. Senile dementia may be associated with significantly lower BIS values. CONCLUSIONS:The BIS is a useful guidance for titration of anaesthetic drugs in the elderly. The presence of senile dementia may be a confounding factor in the interpretation of the BIS values during anaesthesia.
Bispectral index-guided anesthesia in patients undergoing aortocoronary bypass grafting.
Lehmann Andreas,Karzau Julia,Boldt Joachim,Thaler Elfi,Lang Johannes,Isgro Frank
Anesthesia and analgesia
In this prospective, randomized study, we compared hemodynamics, oxygenation, possible intraoperative awareness, and costs in 62 patients undergoing first-time elective coronary artery bypass grafting at 2 different levels of anesthesia. Depth of anesthesia was assessed with bispectral index (BIS). All patients were anesthetized with sufentanil/midazolam. The dosage of sufentanil/midazolam was adjusted to achieve a BIS level of 45-55 in 32 patients (Group BIS 50), whereas in 30 patients a BIS level of 35-45 was intended (Group BIS 40). Data were obtained at six different time points before, during, and after surgery. All patients were asked about possible intraoperative awareness on the third postoperative day. There were no significant differences of any hemodynamic or oxygenation variables at any time between the two groups. BIS 40 patients received significantly (P < 0.05) more sufentanil (BIS 40, 888 +/- 211 microg; BIS 50, 514 +/- 99 microg) and midazolam (BIS 40, 22.4 +/- 5.6 mg; BIS 50, 16.6 +/- 3.7 mg) than BIS 50 patients. The reduction in anesthetic drugs used saved euro;13.78/US$12.54 per patient (P < 0.05) in Group BIS 50, but one BIS electrode caused additional costs of 19.95 Euros/18.15 US dollars. Time to extubation was not significantly prolonged in Group BIS 40 (BIS 40, 14.3 +/- 4.6 h; BIS 50, 11.8 +/- 3.8 h). There was no explicit memory during anesthesia in either group. BIS-guided reduction of anesthetic medication saved costs and did not increase the risk of intraoperative awareness. However, total costs were increased by monitoring BIS, because of the BIS electrodes.
10.1097/00000539-200302000-00008
The bispectral index declines during neuromuscular block in fully awake persons.
Messner M,Beese U,Romstöck J,Dinkel M,Tschaikowsky K
Anesthesia and analgesia
UNLABELLED:Bispectral index (BIS) is an electroencephalographic variable promoted for measuring depth of anesthesia. Electromyographic activity influences surface electroencephalography and the calculation of BIS. In this study, we sought to determine the effect of spontaneous electromyographic activity on BIS. BIS was monitored in three volunteers by using an Aspect A-1000 monitor. The experiment was repeated in one volunteer. Electromyographic activity was recorded. Alcuronium and succinylcholine were administered. No other drugs were used. In parallel with spontaneous electromyographic activity of the facial muscles, BIS decreased in response to muscle relaxation to a minimum value of 33 and, in the repeated measurement, to a minimum value of 9 when total neuromuscular block was achieved. In two volunteers, no total block was achieved. BIS decreased to a minimal value of 64 and 57, respectively. In turn, recovery of BIS coincided with the reappearance of spontaneous electromyographic activity. During the entire experiment, the volunteers had full consciousness. BIS, assessed by software Version 3.31, correlates with spontaneous electromyographic activity of the facial muscles. BIS failed to detect awareness in completely paralyzed subjects. Thus, in paralyzed patients, BIS monitoring may not reliably indicate a decline in sedation and imminent awareness. IMPLICATIONS:The bispectral index (BIS) is an electroencephalographic variable intended for measuring depth of anesthesia. Electromyographic activity influences the calculation of BIS. We found that the administration of a muscle relaxant to unanesthetized volunteers decreases the bispectral index value. Thus, awareness in totally paralyzed patients cannot be excluded.
10.1213/01.ANE.0000072741.78244.C0
Antagonism of neuromuscular blockade but not muscle relaxation affects depth of anaesthesia.
Vasella F C,Frascarolo P,Spahn D R,Magnusson L
British journal of anaesthesia
BACKGROUND:Conflicting effects of neuromuscular blocking drugs and anticholinesterases on depth of anaesthesia have been reported. Therefore we evaluated the effect of atracurium and neostigmine on bispectral index (BIS) and middle-latency auditory evoked potentials (AAI). METHODS:We studied 40 patients (ASA I-II) aged 18-69 yr. General anaesthesia consisted of propofol and remifentanil by target-controlled infusion and neuromuscular function was monitored by electromyography. When BIS reached stable values, patients were randomly assigned to one of two groups. Group 1 received atracurium 0.4 mg kg(-1) and, 5 min later, the same volume of NaCl 0.9%; group 2 received saline first and then atracurium. When the first twitch of a train of four reached 10% of control intensity, patients were again randomized: one group (N) received neostigmine 0.04 mg kg(-1) and glycopyrrolate 0.01 mg kg(-1), and the control group (G) received only glycopyrrolate. RESULTS:Injection of atracurium or NaCl 0.9% had no effect on BIS or AAI. After neostigmine-glycopyrrolate, BIS and AAI increased significantly (mean maximal change of BIS 7.1 [SD 7.5], P<0.001; mean maximal change of AAI 9.7 [10.5], P<0.001). When glycopyrrolate was injected alone BIS and AAI also increased (mean maximal change of BIS 2.2 [3.4], P=0.008; mean maximal change of AAI 3.5 [5.7], P=0.012), but this increase was significantly less than in group N (P=0.012 for BIS; P=0.027 for AAI). CONCLUSION:These data suggest that neostigmine alters the state of propofol-remifentanil anaesthesia and may enhance recovery.
10.1093/bja/aei120
Can electroencephalographic analysis be used to determine sedation levels in critically ill patients?
Roustan Jean-Paul,Valette Sarah,Aubas Pierre,Rondouin Gérard,Capdevila Xavier
Anesthesia and analgesia
UNLABELLED:Prolonged use of sedative drugs frequently leads to oversedation of intensive care patients. Clinical assessment scales are not reliable in deeply sedated patients. Parameters obtained from spectral and bispectral analysis of electroencephalogram (EEG) records have been combined to create an index (BIS) to monitor anesthesia depth. The role of such parameters in monitoring the depth of the sedation in intensive care unit (ICU) patients has yet to be determined. We designed the present prospective study to redefine and calculate available spectral and bispectral parameters from raw EEG records and estimate their clinical relevance for the diagnosis of under- or oversedation levels in ICU patients. Forty adult patients receiving continuous midazolam and morphine sedation were included. We obtained 167 clinical evaluations of sedation level using Ramsay and COMFORT scales along with an EEG record of 300 s. Six spectral parameters-relative power of 4 frequency bands (beta, alpha, Theta, and delta), 95th percentile of the power spectrum (SEF95), and 50th percentile of the power spectrum (SEF50) and four bispectral parameters, real triple product, bispectrum (Bispectrum), bicoherence, and ratio 10-were calculated. The relevance of each of these parameters and combinations in predicting too light (Ramsay 1 and 2) or deep (Ramsay 5 and 6) sedation levels was assessed. These calculations were performed before and after exclusion of the agitated patients, whose COMFORT 4 score was above 2. The most relevant parameters for predicting levels of deep sedation (Ramsay 5 and 6) were ratio 10 (area under the curve = 0.763; 95% confidence interval, 0.679-0.833) and SEF95 (area under the curve = 0.687; 95% confidence interval, 0.597-0.767). The most relevant parameters for predicting light levels of sedation (Ramsay 1 and 2) were also ratio 10 (area under the curve = 0.829; 95% confidence interval, 0.695-0.917) and SEF95 (area under the curve = 0.798; 95% confidence interval, 0.650-0.898). There is a modest improvement in relevance of their linear combination in predicting sedation level. Results were similar after exclusion of agitated patients. We conclude that various calculated EEG descriptive parameters exhibited large interindividual variability. There was a strong correlation between EEG spectral and bispectral parameters. Bispectral analysis slightly improves the predictive power of simple spectral analysis in distinguishing too light or deep sedation levels in ICU patients. IMPLICATIONS:Spectral edge frequency 95 and Ratio 10 are the most relevant electroencephalogram (EEG) indexes for monitoring the level of sedation in intensive care unit patients but calculated EEG values exhibited large interindividual variability. Bispectral analysis of EEG provides a slight improvement over simple spectral analysis.
10.1213/01.ane.0000167782.47957.e1
The effect of addition of nitrous oxide to a sevoflurane anesthetic on BIS, PSI, and entropy.
Soto Roy G,Smith Robert A,Zaccaria Amy L,Miguel Rafael V
Journal of clinical monitoring and computing
OBJECTIVE:N(2)O is a commonly used anesthetic that has amnestic and analgesic properties. Recently, devices that estimate depth of consciousness have been introduced in an attempt to better titrate anesthesia, however the effect of N(2)O on these monitors is unclear. METHODS:General anesthesia was induced and titrated to maintain normal blood pressure and pulse in healthy adults. Data were collected in three 10 minute intervals (Sevo, Sevo + N(2)O, Sevo). In Phase A, sevoflurane concentration was held constant during the N(2)O trial in 60 subjects monitored with either BIS, PSI, or Entropy. In Phase B, sevoflurane concentration was reduced as N(2)O was added, maintaining a constant overall "MAC" in 20 subjects monitored concurrently with BIS and Entropy. Sample size for both phases was designed to detect a 10 unit change in measure of processed EEG with alpha = .05 and statistical power = .80. RESULTS:In Phase A, supplementing sevoflurane with > 65% N(2)O increased MAC from 1.3 +/- 0.05 to 2.2 +/- 0.10, but did not significantly alter BIS nor PSI (p-value for differential MAC is < 0.05). Entropy, however, dropped significantly, with a change in state entropy (SE) from 31.1 +/- 7.3 to 18.9 +/- 3.7 and a corresponding rise when N(2)O was discontinued. In Phase B, supplementing sevoflurane with > 65% N(2)O with a concomitant reduction in sevoflurane resulted in an increase in both BIS (from 34 +/- 5 to 53.9 +/- 11.5) and SE (from 32 +/- 8.2 to 55.4 +/- 21.3). CONCLUSION:Supplementing sevoflurane with > 65% N(2)O did not result in a significant change in either BIS or PSI when sevoflurane concentration was kept constant. Entropy, however, significantly decreased as anesthetic depth increased. When sevoflurane concentration was reduced during N(2)O administration, both BIS and Entropy rose despite maintenance of anesthetic depth, indicating a variable concentration effect between volatiles and N(2)O.
10.1007/s10877-006-9009-0
[Assessing the depth-of-hypnosis].
Høymork Siv Cathrine
Tidsskrift for den Norske laegeforening : tidsskrift for praktisk medicin, ny raekke
BACKGROUND:There has been a breakthrough in the understanding of anaesthetic drug effects during the last two decades, and new monitors aimed at quantifying such effects have been developed. MATERIAL AND METHODS:This review is based on publications from the last 15 years, oral presentations, and rewritten parts of the author's PhD thesis. RESULTS:General anaesthesia can be regarded as a combination of hypnosis (sleep), analgesia and muscle relaxation. Modern anaesthetic drugs aim at each of these effects separately. Pharmacological variation makes it impossible to find one dose suitable for all, so tools for measuring drug effects in the individual patient are warranted. Monitors for measuring depth-of-hypnosis and partly analgesic effect are commercially available. Among these, BIS (bispectral index), based on EEG, is by far the best documented. BIS is proven useful for preventing undesired awareness and overdosing, but there are major limitations. Use of such technology in clinical practice is under constant debate. INTERPRETATION:Even though the BIS technology is promising and used widely, no health authorities have so far recommended that such monitors should be compulsory during general anaesthesia, but rather that it should be considered on an individual basis. So far, it seems like this is a sensible approach in Norway as well.
10.4045/tidsskr.08.0396
[Influence of processed EEG monitoring in the anesthetic management and its cost in off-pump coronary surgery: a research protocol].
Martins Ana,Pereira Ana,Seabra Helena,Gomes Diana,Fonte Boa Ana,Lima Fátima
Revista portuguesa de cirurgia cardio-toracica e vascular : orgao oficial da Sociedade Portuguesa de Cirurgia Cardio-Toracica e Vascular
BACKGROUD:Although in some studies intraoperative processed EEG monitoring has shown advantages such as less use of hypnotic drugs and decrease duration of both anesthetic emergency and recovery times, there is controversy on the incidence of awareness. It has not been demonstrated that this type of monitoring interferes with length of hospital stay, morbidity and mortality. Processed EEG monitoring, such as the bispectral index (BIS) has been widely accepted in assessing anesthetic depth, yet its usage is not part of the standard monitoring of the American Society of Anesthesiologiy (ASA). Other forms of monitoring anesthetic depth widely used are clinical monitoring associated with monitoring expiratory fraction of halogenated anesthetic agents. METHODOLOGY:Prospective randomized study comparing two groups of patients undergoing coronary artery bypass surgery without cardiopulmonary bypass (CPB): group A - BIS visible (BIS value is shown throughout the procedure) and group B - BIS not visible (BIS is hidden and monitoring of anesthetic depth is based on clinical signs associated with the monitoring of expiratory fraction of halogenated anesthetic agent). The aim of this study is to verify the existence of differences in anesthetic depth and associated costs in the two group study's and also to add evidence to anesthetic depth monitoring in an area where few studies have been done - cardiac surgery.
Navigator® and SmartPilot® View are helpful in guiding anesthesia and reducing anesthetic drug dosing.
Cirillo V,Zito Marinosci G,De Robertis E,Iacono C,Romano G M,Desantis O,Piazza O,Servillo G,Tufano R
Minerva anestesiologica
BACKGROUND:The recently introduced Navigator® (GE Healthcare, Helsinki, Finland) and SmartPilot® View (Dräger Medical, Lübeck, Germany) show the concentrations and predicted effects of combined anesthetic drugs, and should facilitate more precisely their titration. Our aim was to evaluate if Navigator® or SmartPilot® View guided anesthesia was associated with a good quality of analgesia, depth of hypnosis and may reduce anesthetic requirements. METHODS:We performed a prospective non-randomized study. Sixty ASA I-II patients undergoing balanced general anesthesia for abdominal and plastic surgery were enrolled. Patients were divided in 4 groups. Group 1 (N. 15) and group 3 (N. 15) were cases in whom anesthesia was performed with standard monitoring plus the aid of Navigator® (Nav) or SmartPilot® View (SPV) display. Group 2 (N. 15) and group 4 (N. 15) were controls in whom anesthesia was performed with standard monitoring (heart rate, NIBP, SpO2, end-tidal CO2, end-expired sevoflurane concentration, train of four, Bispectral Index [Aspect Medical Systems, Natick, MA, USA] or Entropy [GE Healthcare]). Patients' vital parameters and end-expired sevoflurane concentration were recorded during anesthesia. RESULTS:All patients recovered uneventfully and showed hemodynamic stability. End-tidal sevoflurane concentrations values [median (min-max)], during maintenance of anesthesia, were significantly (P<0.05) lower in SPV [1.1% (0.8-1.5)] and Nav [1%(0.8-1.8)] groups compared to SPV-control group [1.5%(1-2.5)] and Nav-control group [1.5%(0.8-2)]. BIS and entropy values were respectively higher in the SPV group [53 (46-57)] compared to the control group [43 (37-51)] (P<0.05) and Nav group [53 (43-60)] compared to the control group [41 (35-51)] (P<0.05). No significant differences in Remifentanil dosing were observed in the four groups. CONCLUSION:Navigator® and SmartPilot® View may be of clinical use in monitoring adequacy of anesthesia. Both displays can optimize the administration and monitoring of anesthetic drugs during general anesthesia and may reduce the consumption of volatile anesthetic agents.
Response of bispectral index to neuromuscular block in awake volunteers.
Schuller P J,Newell S,Strickland P A,Barry J J
British journal of anaesthesia
BACKGROUND:The bispectral index (BIS) monitor is a quantitative electroencephalographic (EEG) device that is widely used to assess the hypnotic component of anaesthesia, especially when neuromuscular blocking drugs are used. It has been shown that the BIS is sensitive to changes in electromyogram (EMG) activity in anaesthetized patients. A single study using an earlier version of the BIS showed that decreased EMG activity caused the BIS to decrease even in awake subjects, to levels that suggested deep sedation and anaesthesia. METHODS:We administered suxamethonium and rocuronium to 10 volunteers who were fully awake, to determine whether the BIS decreased in response to neuromuscular block alone. An isolated forearm technique was used for communication during the experiment. Two versions of the BIS monitor were used, both of which are in current use. Sugammadex was used to antagonise the neuromuscular block attributable to rocuronium. RESULTS:The BIS decreased after the onset of neuromuscular block in both monitors, to values as low as 44 and 47, and did not return to pre-test levels until after the return of movement. The BIS showed a two-stage decrease, with an immediate reduction to values around 80, and then several minutes later, a sharp decrease to lower values. In some subjects, there were periods where the BIS was <60 for several minutes. The response was similar for both suxamethonium and rocuronium. Neither monitor was consistently superior in reporting the true state of awareness. CONCLUSIONS:These results suggest that the BIS monitor requires muscle activity, in addition to an awake EEG, in order to generate values indicating that the subject is awake. Consequently, BIS may be an unreliable indicator of awareness in patients who have received neuromuscular blocking drugs. CLINICAL TRIAL REGISTRY NUMBER:ACTRN12613000587707.
10.1093/bja/aev072
Esmolol reduces anesthetic requirements thereby facilitating early extubation; a prospective controlled study in patients undergoing intracranial surgery.
Asouhidou Irene,Trikoupi Anastasia
BMC anesthesiology
BACKGROUND:Adequate cerebral perfusion pressure with quick and smooth emergence from anesthesia is a major concern of the neuroanesthesiologist. Anesthesia techniques that minimize anesthetic requirements and their effects may be beneficial. Esmolol, a short acting hyperselective β-adrenergic blocker is effective in blunting adrenergic response to several perioperative stimuli and so it might interfere in the effect of the anesthetic drugs on the brain. This study was designed to investigate the effect of esmolol on the consumption of propofol and sevoflurane in patients undergoing craniotomy. METHOD:Forty-two patients that underwent craniotomy for aneurysm clipping or tumour dissection were randomly divided in two groups (four subgroups). Anesthesia was induced with propofol, fentanyl and a single dose of cis-atracurium, followed by continuous infusion of remifentanil and either propofol or sevoflurane. Patients in the esmolol group received 500 mcg/kg of esmolol bolus 10 min before induction of anesthesia, followed by additional 200 mcg/kg/min of esmolol. Monitoring of the depth of anesthesia was also performed using the Bispectral Index-BIS and cardiac output. The inspired concentration of sevoflurane and the infusion rate of propofol were adjusted in order to maintain a BIS value between 40-50. Intraoperative emergence was detected by the elevation of BIS value, HR or MAP. RESULTS:The initial and the intraoperative doses of propofol and sevoflurane were 18-50 mcg/kg/min and 0.2-0.5 MAC respectively in the esmolol group, whereas in the control group they where 100-150 mcg/kg/ and 0.9-2.0 MAC respectively (p = 0.000 for both groups). All procedures were anesthesiologically uneventful with no episodes of intraoperative emerge. CONCLUSIONS:Esmolol is effective not only in attenuating intraoperative hemodynamic changes related to sympathetic overdrive but also in minimizing significant propofol and sevoflurane requirements without compromising the hemodynamic status. ClinicalTrials.gov Identifier: NCT02455440 . Registered 26 May 2015.
10.1186/s12871-015-0154-1
Effects of neuromuscular blockade reversal on bispectral index and frontal electromyogram during steady-state desflurane anesthesia: a randomized trial.
Kim Doyeon,Ahn Jin Hee,Jung Hyunjoo,Choi Ka Young,Jeong Ji Seon
Scientific reports
The degree of neuromuscular blockade reversal may affect bispectral index (BIS) value. One possible reason is that the reverse of neuromuscular blockade affects electromyographic (EMG) signals of fascial muscle. Another reason is, the afferentation theory, the reverse of neuromuscular blockade relieves block signals generated in muscle stretch receptors from accessing the brain through afferent nerve pathways and induces arousal. Inaccurate BIS value may lead to overdose of drugs or the risk of intraoperative awareness. We compared changes in BIS and EMG values according to neuromuscular blockade reversal agents under steady-state desflurane anesthesia. A total of 65 patients were randomly allocated to receive either neostigmine 0.05 mg/kg, sugammadex 4 mg/kg, or pyridostigmine 0.25 mg/kg for neuromuscular blockade reversal under stable desflurane anesthesia, and 57 patients completed the study. The primary outcome was change in BIS and EMG values before and after administration of neuromuscular blockade reversal agents (between train-of-four [TOF] count 1-2 and TOF ratio 0.9). The change in BIS and EMG values before and after administration of neuromuscular blockade reversal agents were statistically different in each group (BIS: Neostigmine group, P < 0.001; Sugammadex group, P < 0.001; Pyridostigmine group, P = 0.001; EMG: Neostigmine group, P = 0.001; Sugammadex group, P < 0.001; Pyridostigmine group, P = 0.001; respectively). The BIS and EMG values had a positive correlation (P < 0.001). Our results demonstrate that the EMG and BIS values have increased after neuromuscular blockade reversal under desflurane anesthesia regardless of the type of neuromuscular blockade reversal agent. BIS should be applied carefully to measure of depth of anesthesia after neuromuscular blockade reversal.
10.1038/s41598-019-47047-1
Effect of Different Concentrations of Propofol Used as a Sole Anesthetic on Pupillary Diameter: A Randomized Trial.
Sabourdin Nada,Meniolle Fleur,Chemam Sarah,Rigouzzo Agnes,Hamza Jamil,Louvet Nicolas,Constant Isabelle
Anesthesia and analgesia
BACKGROUND:Pupillometry monitoring under general anesthesia is based on the assumption that pupillary diameter variations reflect the adequacy of the provided analgesia to the intensity of the nociceptive surgical stimulus. The accurate interpretation of pupillometric data requires establishing clearly what the expected baseline unstimulated pupillary diameter at each specific level of hypnosis is. Opioids decrease pupillary diameter in a dose-dependent fashion. In contrast, the effects of hypnotic drugs on pupillary diameter are not well known. Our aim was to describe the potential relationship between propofol predicted effect-site concentrations (Cets) ranging from 1 to 3 µg/mL and pupillary diameter. METHODS:Patients were randomized to receive propofol by target-controlled infusion at a predicted Cet of 1, 2, or 3 µg/mL (groups P1, P2, and P3, respectively). Pupillary diameter measurements were performed after 10 minutes of steady-state propofol infusion at the randomized Cet. No stimulation was performed during the study. Heart rate and bispectral index (BIS) were continuously recorded. RESULTS:Forty patients were included: (13, 14, and 13 in groups P1, P2, and P3, respectively). Mean pupillary diameter was 5.7 mm (1 mm) in group P1, 4.8 mm (1.3 mm) in group P2, and 3.3 mm (0.8 mm) in group P3. Propofol had a dose-dependent effect on pupillary diameter (linear regression R = 0.45, P < .001). Pupillary diameter was positively correlated with the BIS (Spearman r = 0.75 [95% confidence interval (CI), 0.54 to -0.87] P < .001). CONCLUSIONS:From 1 to 3 µg/mL of predicted Cet, propofol has a dose-dependent effect on pupillary diameter. Within this concentrations range, there is a positive correlation between BIS and pupillary diameter. The subcortical effect of propofol on pupillary diameter is correlated to its effect on the cortex. Studies assessing pupillary diameter as a marker of the nociception-antinociception balance should be performed in patients with a standardized depth of hypnosis.
10.1213/ANE.0000000000004362
Reversal of neuromuscular blockade with sugammadex during continuous administration of anaesthetic agents: a double-blind randomised crossover study using the bispectral index.
Le Guen M,Roussel C,Chazot T,Dumont G A,Liu N,Fischler M
Anaesthesia
Sugammadex, a specific reversal agent for steroidal neuromuscular blocking drugs, has on occasion been reported to be associated with clinical signs of awakening. We performed a study to systematically search for an increase in bispectral index values and signs of awakening in patients maintained under general anaesthesia following sugammadex administration. Patients, scheduled to receive general anaesthesia with neuromuscular blockade, were included in this double-blind randomised crossover study. After surgery was completed, and while the train-of-four ratio was zero, intravenous anaesthesia was continued with the aim of maintaining the bispectral index in the range of 40-60. Patients then received either sugammadex 4 mg.kg or saline. In cases of incomplete reversal of neuromuscular blockade after 5 min, patients received the other drug. Bispectral index and train-of-four monitoring were recorded every minute and clinical signs of awakening noted. Fifty-one patients completed the study. Median (IQR [range]) bispectral index values increased after sugammadex administration from 49 (43-53 [38-64]) to 63 (53-80 [45-97]) (p < 0.01) with an increase of ≥ 20 in 22 patients; 14 (27%) patients had clinical signs of awakening. Saline had no effect on bispectral index values, clinical signs of awakening or degree of neuromuscular blockade. This study confirms that reversal of neuromuscular blockade with sugammadex may be associated with clinical signs of awakening despite maintenance of anaesthesia. Intravenous anaesthesia should be maintained until complete recovery of muscle function is achieved, especially when sugammadex is administered.
10.1111/anae.14897
Anesthetic Stability of Propofol, Dexmedetomidine, and Isoflurane by Measuring Bispectral Index (BIS) and Hemodynamic Indices: A Comparative Study.
Cureus
Background Hemodynamic changes and anesthetic awareness occurring during surgery under general anesthesia is a great concern for both surgeon and anesthesiologist. Maintenance of the adequate depth of anesthesia throughout the intraoperative period is important in maintaining hemodynamic stability, preventing intraoperative awareness, and avoiding postoperative recall. Aim This study aims to predict the anesthetic stability of propofol, dexmedetomidine, and isoflurane by measuring bispectral index (BIS) and hemodynamic indices. Materials and methods This is a prospective comparative study. Sixty patients of either sex, aged 18-60 years, with American Society of Anesthesiologist (ASA) physical status classification I and II, undergoing elective surgical procedures requiring general anesthesia were allocated into three groups of 20 each. Patients in each group were administered standard general anesthesia with routine hemodynamic monitoring along with BIS, and values were recorded at baseline and thereafter at every five-minute interval for the duration of surgery. Anesthesia was maintained in Group P using a bolus dose of propofol 1 milligram.kg for 10 minutes followed by propofol infusion 50-75 microgram.kg.minute, Group D with a bolus dose of dexmedetomidine 1 microgram.kg for 10 minutes followed by infusion 0.2-0.7 microgram.kg.hour, and Group I with isoflurane at 1 minimum alveolar concentration (MAC) for 10 minutes and then maintained between 0.5 MAC and 1.5 MAC until the duration of surgery. To maintain the surgical plane of anesthesia, the BIS score was monitored between 40 and 65. The quantitative variables were expressed as mean±SD and compared between groups using Student's unpaired t-test. Data analysis was done using SPSS Statistics for Windows version 20.0 (IBM Corp., Armonk, NY, USA). A p-value of <0.05 was considered statistically significant. Results During intergroup comparison among study drugs, the mean BIS values were statistically significant among the groups (p<0.05). Hemodynamic indices were significantly better maintained in the dexmedetomidine group as compared to the isoflurane and propofol groups throughout the intraoperative period (p<0.05). Conclusion Dexmedetomidine is better than propofol and isoflurane in maintaining the BIS score and hemodynamic parameters during the intraoperative period.
10.7759/cureus.24930
Comparison of recovery profiles in target-controlled infusions (TCI) versus manually controlled infusions for total intravenous anesthesia (TIVA) in laparoscopic surgeries. A randomized controlled trial.
Journal of anaesthesiology, clinical pharmacology
Background and Aims:Considerable importance has been attached to early recovery and discharge readiness after surgeries. Many centers use total intravenous anesthesia (TIVA) as their anesthesia technique of choice. Target-controlled infusions (TCI) have been proposed as a method to precisely deliver continuous infusions of propofol and opioids as compared to the traditionally used manual-controlled infusion (MCI) methods. However, TCI has also been shown to result in the administration of larger doses of propofol which could cause delayed emergence and recovery from anesthesia. Studies involving TCI have focused mainly on its effects on anesthesia induction but not much literature is available on recovery profiles of patients on TCI. This study was designed to compare the effect of conventionally used MCI methods versus the target-controlled infusion (TCI) method of administering TIVA on recovery characteristics in patients undergoing laparoscopic surgery. Material and Methods:This was a prospective randomized interventional study on 54 patients. Our primary objective was to compare the rates of recovery from anesthesia as judged by four parameters. Time to return of spontaneous ventilation, time to respond to verbal commands, time to extubation, and time to shift patient out of the operating room after stoppage of propofol infusion. As secondary objectives, intraoperative average bispectral index (BIS) values and total anesthetic drugs (propofol and fentanyl) consumption were also compared. Results:We noted that for laparoscopic surgeries lasting less than 4 hours, both MCI and TCI techniques of TIVA have comparable rates of recovery after the stoppage of propofol infusion. Total consumption of propofol and fentanyl was also similar; however, with the use of the TCI method of TIVA, better depth of anesthesia as evidenced by lower average BIS levels was noted. Conclusion:Recovery rates after TIVA using a target-controlled infusion (TCI) system are similar to BIS-guided MCIs in patients undergoing laparoscopic surgery lasting less than 4 hours. TCI resulted in better depths of anesthesia though per kg/min consumption of propofol was found to be more.
10.4103/joacp.joacp_396_21
Dexmedetomidine Infusion Versus Placebo During Light or Deep Anesthesia on Postoperative Delirium in Older Patients Undergoing Major Noncardiac Surgery: A Pilot Randomized Factorial Trial.
Anesthesia and analgesia
BACKGROUND:Postoperative delirium (POD) is common among older surgical patients and may be affected by dexmedetomidine and depth of anesthesia. We designed this pilot study to assess the feasibility of comparing dexmedetomidine with normal saline during light versus deep anesthesia on POD in older patients undergoing major noncardiac surgery. METHODS:In this pilot randomized factorial study, 80 patients aged 60 years or older undergoing major noncardiac surgery were randomized (1:1:1:1) to receive dexmedetomidine infusion 0.5 μg/kg/h or normal saline placebo during light (bispectral index [BIS] target 55) or deep (BIS target 40) anesthesia. Feasibility end points included consent rate and dropout rate, timely enrollment, blinded study drug administration throughout surgery, no inadvertent unmasking, achieving BIS target throughout >70% of surgery duration, and the process of twice-daily POD screening. In addition, we estimated the POD incidences in the 2 control groups (placebo and deep anesthesia) and treatment effects of dexmedetomidine and light anesthesia. RESULTS:Between November 1, 2021, and June 30, 2022, 78 patients completed the trial (mean [standard deviation, SD] age, 69.6 [4.6] years; 48 male patients [62%]; dexmedetomidine-deep, n = 19; dexmedetomidine-light, n = 20; placebo-deep, n = 19; placebo-light, n = 20). This study had a high consent rate (86%) and a low dropout rate (2.5%). Average recruitment was 5 patients at each center per month. Dexmedetomidine and normal saline were administered in a blinded fashion in all patients. Unmasking did not occur in either group. Approximately 99% of patients received the scheduled study drug infusion throughout the surgery. Approximately 81% of patients achieved the BIS targets throughout >70% of the surgery duration. The scheduled twice-daily POD screening was completed without exception. Overall, 10 of the 78 patients (13%; 95% confidence interval [CI], 7%-22%) developed POD. For the 2 reference groups, POD was observed in 7 of the 39 patients (17.9%; 95% CI, 9%-32.7%) in the placebo group and 7 of the 38 patients (18.4%; 95% CI, 9.2%-33.4%) in the deep anesthesia group. Regarding the treatment effects on POD, the estimated between-group difference was -10% (95% CI, -28% to 7%) for dexmedetomidine versus placebo, and -11% (95% CI, -28% to 6%) for light versus deep anesthesia. CONCLUSIONS:The findings of this pilot study demonstrate the feasibility of assessing dexmedetomidine versus placebo during light versus deep anesthesia on POD among older patients undergoing major noncardiac surgery, and justify a multicenter randomized factorial trial.
10.1213/ANE.0000000000006686