Changes In Bispectral Index Research Articles

Comparison of remimazolam tosylate and propofol in patients undergoing general anesthesia using a laryngeal mask airway without muscle relaxants

It has been reported that anesthesia using propofol can frequently induce hypotension. Herein, we designed this study to compare the incidence of hypotension induced by propofol or remimazolam during laryngeal mask airway (LMA) anesthesia without muscle relaxants. 95 patients aged 18 to 65 years undergoing LMA anesthesia without muscle relaxants were randomly allocated to two groups. After 0.2 µg/kg sufentanil, Group P received a bolus dose of 2 mg/kg propofol followed by a continuous propofol infusion, while Group R received a bolus dose of 0.3 mg/kg remimazolam followed by a continuous remimazolam infusion. The primary outcome was hypotension, defined as systolic blood pressure falling below 90 mmHg during anesthesia. Secondary outcomes included other adverse events. The success rate of initial LMA insertion, LMA insertion conditions, LMA removal time and changes in bispectral index (BIS) and hemodynamics during anesthesia induction, were also assessed. The results showed that the incidence of hypotension was not significantly different between the two groups (47.9% in group P and 36.2% in group R, p = 0.246). However, the BIS and heart rate during induction of anesthesia were significantly higher in group R than in group P (p < 0.05). Also, hiccups were more common in group R than in group P (14.9% vs. 2.1%, p = 0.031), and the LMA removal time was significantly longer in group R than in group P (12 min vs. 8 min, p = 0.001). We did not find a significantly lower incidence of hypotension in patients undergoing LMA anesthesia without muscle relaxants when comparing remimazolam to propofol, potentially related to the study’s small sample size, and conducting a large-scale study using similar conditions could be inappropriate due to the risk of remimazolam-induced hiccups.

Bispectral Index Changes Following Boluses of Commonly Used Intravenous Medications During Volatile Anesthesia Identified From Retrospective Data.

Although patients are commonly monitored for depth of anesthesia, it is unclear to what extent administration of intravenous anesthetic medications may affect calculated bispectral (BIS) index values under general anesthesia. In a retrospective analysis of electronic anesthesia records from an academic medical center, we examined BIS index changes associated with 14 different intravenous medications, as administered in routine practice, during volatile-based anesthesia using a novel screening approach. Discrete-time windows were identified in which only a single drug bolus was administered, and subsequent changes in the BIS index, concentration of volatile anesthetic, and arterial pressure were analyzed. Our primary outcome was change in BIS index, following drug administration. Adjusted 95% confidence intervals were compared to predetermined thresholds for clinical significance. Secondary sensitivity analyses examined the same outcomes, with available data separated according to differences in baseline volatile anesthetic concentrations, doses of the administered medications, and length of time window. The study cohort was comprised of data from 20,170 distinct cases, 54.7% of patients were men, with a median age of 55. In the primary analysis, ketamine at a median dose of 20 mg was associated with a median (confidence limits) increase in BIS index of 3.8 (2.5-5.0). Midazolam (median dose 2 mg) was associated with a median decrease in BIS index of 3.0 (1.5-4.5). Neither of these drug administrations occurred during time periods associated with changes in volatile anesthetic concentration. Analysis for dexmedetomidine was confounded by concomitant decreases in volatile anesthetic concentration. No other medication analyzed, including propofol and common opioids, was associated with a significant change in BIS index. Secondary analyses revealed that similar BIS index changes occurred when midazolam and ketamine were administered at different volatile anesthetic concentrations and different doses, and these changes persisted 11 to 20 minutes postadministration. Modest, but persistent changes in BIS index occurred following doses of ketamine (increase) and midazolam (decrease) during periods of stable volatile anesthetic administration.

Changes in Bispectral Index with different positions during general anaesthesia.

Background & Objective: Bispectral index (BIS) is used for intraoperative anesthesia depth assessment during general anesthesia (GA). This monitoring modality has been used routinely at many centers during GA, but especially during susceptible patients, in which precise depth of anesthesia is required. We aimed to compare changes of BIS in different head positions under GA, but without surgical stimulation. Methodology: Thirty ASA physical status I patients aged 18−60 y were recruited for this prospective, observational study after ethical approval by the institutional ethical review committee. After administration of GA, patients were kept in supine position for 15 min and the BIS, signal quality index (SQI), electromyography (EMG), mean arterial pressure (MAP) and heart rate (HR) were recorded. Patients were then sequentially placed in: reverse Trendelenburg (45°), supine, Trendelenburg (45°) positions, each for 15-min duration and 3 readings were taken in each position at 5 min interval. Lastly patient was positioned back to supine position for the surgery to begin. Results: There was a statistically significant decrease of BIS value with a change from supine position to reverse Trendelenburg position (P = 0.02) and increase in BIS value from supine to Trendelenburg position (P = 0.01). Changing of position from supine to reverse Trendelenburg was found to have a statistically significant decrease in MAP (P = 0.005), whereas changing to Trendelenburg position significantly increased MAP compared to supine position (P < 0.001). There was a positive moderate linear correlation between BIS and MAP (r = 0.513, P = 0.004). Conclusion: A change of position from supine to reverse Trendelenburg decreases and from supine to Trendelenburg position transiently increases the BIS values. Abbreviations: BIS - Bispectral Index; SQI - Signal Quality Index; EMG – Electromyography; MAP - Mean Arterial Pressure Key words: Anesthesia; Anesthesia, General; Bispectral Index; Electroencephalography; Electromyography; Monitoring; Positioning Citation: Kamaruzaman K, Izaham A, Rahman RA, Mokhtar MN. Changes in bispectral index (BIS) with different positions during general anesthesia. Anaesth. pain intensive care 2023;27(3):325−331. DOI: 10.35975/apic.v27i3.1922 Received: June 24, 2022; Reviewed: April 10, 2023; Accepted: April 10, 2023

Post arrest bispectral index monitoring

The bispectral index is electroencephalography-based technology is used to monitor sedation. BIS is a processed EEG parameter, that was designed specifically to assess patient responses to sedation and anesthesia. In this case report, we aimed to discuss the bispectral index changes during resuscitation of a patient who presented with cardiopulmonary arrest in the light of the literature.

Changes in bispectral index and patient state index during sugammadex reversal of neuromuscular blockade under steady-state sevoflurane anesthesia

Few studies have investigated the changes in patient state index (PSI) and bispectral index (BIS) in response to abrupt increase in electromyographic (EMG) activity. These were performed using intravenous anesthetics or reversal agents for neuromuscular blockade (NMB) other than sugammadex. We compared the changes in BIS and PSI values caused by the sugammadex reversal of NMB during steady-state sevoflurane anesthesia. We enrolled 50 patients with American Society of Anesthesiologists physical status 1 and 2. At the end of the surgery, we administered 2 mg kg−1 sugammadex while maintaining sevoflurane for a 10-min study period. The changes in BIS and PSI from baseline (T0) to train of four ratio of 90% were not significantly different (median difference 0; 95% CI − 3 to 2; P = 0.83), neither were the changes in BIS and PSI values from T0 to their maximum values (median difference 1; 95% CI − 1 to 4; P = 0.53). Maximum BIS and PSI were significantly higher than their baseline values (median difference 6; 95% CI 4–9; P < 0.001 and median difference 5; 95% CI 3–6; P < 0.001, respectively). We found weak positive correlations between BIS and BIS-EMG (r = 0.12, P = 0.01), as well as PSI and PSI-EMG (r = 0.25, P < 0.001). Both PSI and BIS were affected to some extent by EMG artifacts after sugammadex administration.

Remimazolam for induction of anesthesia in elderly patients with severe aortic stenosis: a prospective, observational pilot study

BackgroundRemimazolam, a novel benzodiazepine, has been reported to cause less hypotension than propofol during induction of anesthesia. Therefore, remimazolam might be a valuable option in elderly patients with severe aortic stenosis who are considered to be the most vulnerable to hemodynamic instability. We aimed to evaluate the feasibility and hemodynamic effects of remimazolam as an induction agent in elderly patients with severe aortic stenosis.MethodsThis prospective, open-label, single-arm, observational pilot study was conducted in a university hospital between November 2020 and April 2021. We included 20 patients aged 65 years or older scheduled for transcatheter or surgical aortic valve replacement for severe aortic stenosis under general anesthesia. Patients were administered intravenous remimazolam infusion at 6 mg/kg/h combined with 0.25 μg/kg/min of remifentanil infusion. The primary outcome was the vasopressor dosage between the induction of anesthesia and the completion of tracheal intubation. The secondary outcomes included hemodynamic changes, bispectral index changes, and the time from the start of remimazolam infusion to loss of consciousness. We also recorded awareness during anesthesia induction and serious adverse events related to death, life-threatening events, prolonged hospitalizations, and disability due to permanent damage.ResultsTwenty patients aged 84 [79–86] (median [interquartile range]) with American Society of Anesthesiologists physical status 4 were analyzed. Ephedrine 0 [0–4] mg and phenylephrine 0.1 [0–0.1] mg were administered to 14/20 patients (3 doses in 1 patient, 2 doses in 4 patients, and one dose in 9 patients). Loss of consciousness was achieved at 80 [69–86] s after the remimazolam infusion was started. The mean arterial pressure decreased gradually after loss of consciousness but recovered immediately after tracheal intubation. The bispectral index values gradually decreased and reached < 60 at 120 s after loss of consciousness. Neither awareness during induction of anesthesia nor serious adverse events, such as severe bradycardia (< 40 bpm), life-threatening arrhythmia, myocardial ischemia, or anaphylactic reactions were observed.ConclusionsRemimazolam could be used as an induction agent with timely bolus vasopressors in elderly patients with severe aortic stenosis.Trial registrationUMIN Clinical Trials Registry, identifier UMIN000042318.

Comparison of bispectral index targeted end-tidal concentration of desflurane during three phases of orthotopic liver transplantation.

Background and Aims:Reduced inhalational anaesthetic requirement in end-stage liver disease during living donor orthotopic liver transplantation (LD-OLT) is due to increased endogenous opioids. This study evaluated the changes in bi-spectral index (BIS) monitored end-tidal desflurane (ETDes) requirements during ‘dissection’, ‘anhepatic’, and ‘neohepatic’ phases of LD-OLT.Methods:This prospective, cohort study included 40 adults undergoing LD-OLT under general anaesthesia (GA). All patients received BIS-guided desflurane GA. ETDes requirements in three phases of LD-OLT (primary objective); relationship between inhalational anaesthetic requirements and severity of liver disease; and effect of changes in mean arterial pressure (MAP) and body temperature on ETDes concentration for all three phases were also evaluated.Results:ETDes during the ‘dissection’ phase (2.92 ± 0.65%) was > ‘anhepatic’ (2.68 ± 0.85%, P = 0.049) and ‘neohepatic’ phases (2.58 ± 0.71%, P = 0.005). Patients with model of end-stage liver disease (MELD) score < 20 returned significantly greater ETDes than those with MELD score ≥20 during the ‘dissection’ (MELD <20: 3.11 ± 0.49%; MELD ≥20: 2.58 ± 0.77%, P = 0.01) and ‘anhepatic’(MELD <20: 2.96 ± 0.76%; MELD ≥20: 2.17 ± 0.79%, P = 0.003) phases. A positive correlation was observed between ETDes(r = 0.584, P = 0.001) and temperature in the ‘dissection’ phase only.Conclusion:In patients undergoing LD-OLT, BIS monitoring guidance of depth of desflurane GA suggests lower desflurane requirements during ‘anhepatic’ and the ‘neohepatic’ phase of surgery. Also, the desflurane requirement is greater in patients with lesser severity of liver disease.

The effect of remifentanil used during caesarean section on maternal hemodynamics and neonatal outcome - comparison of two dosing regimens

Introduction/Objective. To present and compare maternal and neonatal effects of two remifentanil dosing regimens, used during induction-delivery period of elective caesarean section in attempt to attenuate maternal cardiovascular response to surgical stress. Methods. Seventy-seven ASA I-II parturients were randomly divided into three groups and received the following: A ? 1 ?g/kg remifentanil immediately before the induction to anesthesia followed by 0.15 ?g/ kg/min infusion, interrupted after skin incision; B ? 1 ?g/kg remifentanil bolus immediately before the induction; C ? no remifentanil until delivery. Hemodynamic (blood pressure, heart rate) and bispectral index changes after endotracheal intubation, skin incision, peritoneal incision and delivery, intraoperative anesthetics consumption and neonatal outcome have been compared between the groups. Results. Hemodynamic response to intubation was significantly attenuated (p &lt; 0.001) in groups A and B compared to C. Hemodynamic response to skin incision, peritoneal incision and delivery was significantly attenuated in group A compared to B and C. Thiopentone dose in groups A and B was lower than in group C (p &lt; 0.001); sevoflurane and remifentanil consumption was less in group A compared to B and C (p &lt; 0.001). Apgar scores at 1st minute were ? 8 in all neonates, with no differences in neonatal heart rate, oxygen saturation and umbilical blood gas values (all within normal range). Conclusion. 1 ?g/kg remifentanil bolus followed by 0.15 ?g/kg/min stopped after skin incision, successfully blunted maternal hemodynamic stress response throughout whole induction-delivery period, reduced anesthetic consumption, without affecting neonatal outcome, so it can be considered effective as well as safe to use during induction-delivery period of caesarean section.

Bispectral index monitoring for diagnosis and assessment of severity of hepatic encephalopathy in cirrhotic patients

BackgroundRecent evidence suggests that bispectral index may aid in the diagnosis of hepatic encephalopathy. We evaluated its utility to diagnose, grade and monitor clinical course of hepatic encephalopathy in patients with cirrhosis. Methods200 patients (70.5% males, mean age 39.5±9.1 years) with cirrhosis and 20 healthy controls were enrolled prospectively. Cirrhotic patients were divided into groups based on encephalopathy grades I–IV assessed by West Haven criteria; minimal encephalopathy was assessed by psychometric tests. Bispectral index was measured at baseline and after one week of lactulose therapy in patients with overt encephalopathy, and after 3 months in patients with minimal encephalopathy. ResultsBispectral index scores were significantly different in patients with different grades of encephalopathy; 79.5±4.2, 67.5±4.3, 56.4±3.5, 44.8±3.9 and 85.0±4.3 respectively for grade I, II, III, IV overt and minimal hepatic encephalopathy, but similar (92.6±3.7 vs 93.75±2.8) in cirrhotics without encephalopathy and healthy controls. Bispectral scores’ cut off values for minimal and overt encephalopathy grade I, II, III, IV were 90.5 and 77.5, 70.5, 60.5, 50.5, respectively. Changes in bispectral index after treatment corresponded to cut-off scores for grades of overt and minimal hepatic encephalopathy. ConclusionsBispectral index was found to be useful in diagnosis, grading and monitoring of treatment response in cirrhotic patients with hepatic encephalopathy.

Bispectral index changes during generalised tonic‐clonic seizures

Bispectral index changes during generalised tonic‐clonic seizures

Acupuncture onYintangPoint Decreases Preoperative Anxiety

The aim of this study was to investigate the effect of ear-press needle acupuncture on Yintang point for preoperative anxiety. This was a prospective, randomized, single-blind, controlled study. The study setting was the Department of Anesthesiology in Ankara Training and Research Hospital of Ministry of Health, Ankara, Turkey. The study comprised 52 adult surgical patients. A single, 20-minute session of single-point acupuncture was applied on Yintang (acupuncture group) or sham point (sham acupuncture group). The efficacy of acupuncture was evaluated by means of the changes in bispectral index (BIS) and STAI (State-Trait Anxiety Index). BIS values in the acupuncture group were significantly lower than in the sham group in all time intervals (p<0.0042). BIS values were lower than baseline in the study group during the entire study period (p<0.0004) while no such effect has been observed in the sham group (p>0.0004). Mean values of state anxiety (STAI-S) decreased after acupuncture in the study group (p=0,018), while no change was observed in trait anxiety (STAI-T) (p=0.156). Patients of the sham group showed no change in both parameters (p=0.387 and p=0,116). Ear-press needle acupuncture on Yintang point reduces preoperative anxiety in adult surgical patients.

Human cerebral microcirculation and oxygen saturation during propofol-induced reduction of bispectral index

Propofol reduces cerebral blood flow (CBF) secondary to cerebral metabolic depression. However, in vitro and in vivo studies demonstrate that propofol directly dilates the vascular smooth muscle. This study investigates the effects of propofol-induced changes in bispectral index (BIS) on cerebral microcirculation and oxygenation during craniotomies. In 21 craniotomy patients undergoing routine craniotomy, anaesthesia was maintained with propofol 4-10 mg kg⁻¹ h⁻¹ and remifentanil 0.1-0.4 µg kg⁻¹ min⁻¹. Propofol concentration was adjusted to achieve higher BIS (target 40) or lower BIS (target 20). Regional measurements of capillary venous blood flow (rvCBF), oxygen saturation (srvO₂), and haemoglobin amount (rvHb) at 2 mm (grey matter) and 8 mm (white matter) cerebral depth were randomly performed at higher and lower BIS by combined laser-Doppler flowmetry and spectroscopy. Calculations: approximated arteriovenous difference in oxygen content (avDO₂) and cerebral metabolic rate of oxygen (aCMRO₂). mean values (sd). Mann-Whitney test (*P<0.05). Results Human cerebral microcirculation and oxygen saturation were assessed at propofol dosages 5.1 (2.3) mg kg⁻¹ h⁻¹ [BIS 40 (9)] and 7.8 (2.1) mg kg⁻¹ h⁻¹ [BIS 21 (7)]. Propofol-induced reduction in BIS resulted in increased srvO₂ (P=0.018), and decreased avDO₂ (P=0.025) and aCMRO(2) (P=0.022), in 2 mm cerebral depth, while rvCBF and rvHb remained unchanged. In 8 mm cerebral depth, srvO₂, rvCBF, rvHb, and also calculated parameters avDO₂ and aCMRO₂ remained unaltered. Findings suggest alteration of the CBF/CMRO₂ ratio by propofol in cortical brain regions; therefore, it might be possible that propofol affects coupling of flow and metabolism in the cerebral microcirculation.

Bispectral Index Changes during Acute Brainstem TIA/Ischemia

We describe a 76-year-old patient who suffered a brainstem TIA just before being anesthetised for cardiac surgery. The TIA was registered on BIS and resulted in a drop in BIS to a value of 60. When consciousness returned spontaneously, the BIS increased to 85. The relative use of the BIS during an operation is discussed. We believe that the lack of input from the brainstem to the frontal cortex resulted in the reduced cortical electrical activity as registered with the BIS.

The performance of Bispectral Index in children during equi-MAC halothane vs. sevoflurane anaesthesia

The reliability of the Bispectral Index for evaluating and monitoring the depth of general anaesthesia in children is not as great as for that in adults. Therefore we analysed Bispectral Index performance in children by comparing changes in Bispectral Index values during a standardized and equipotent anaesthetic regimen using either halothane or sevoflurane for the induction and maintenance of general anaesthesia. Special interest was focussed on excitation during induction, and whether it was associated with simultaneous changes in Bispectral Index scores. Twenty children (3-15 yr, ASA I-II) scheduled for general surgery were randomly allocated to either halothane (10 patients) or sevoflurane group (10 patients). Anaesthesia was induced by 3% halothane or 7% sevoflurane, either agent administered with 50% N2O in oxygen for 5 min, the period from the beginning of induction until intubation. Thereafter, anaesthesia was maintained by the respective volatile agent at 1 MAC (minimum alveolar concentration; in addition to 70% N2O in oxygen) and supplemented with remifentanil infusion adjusted to maintain the heart rate and mean arterial pressure to within 20% of the baseline values. Excitation at induction was defined as involuntary muscular movements. Sevoflurane induction produced a more rapid depression in Bispectral Index than halothane, the mean difference being greatest (47 Bispectral Index score) at 105 s. Excitation occurred in three patients during sevoflurane induction, which coincided with increases in Bispectral Index values in two of the three patients. During the maintenance phase at 1 MAC, the Bispectral Index (mean +/- SD) was 57+/-7 for halothane and 47+/-9 for sevoflurane (P < 0.05). The remifentanil doses did not differ between both groups. In children, halothane anaesthesia was associated with higher Bispectral Index values than sevoflurane when administered at 1 MAC. Large individual variation in Bispectral Index occurred within both groups. Due to these limitations, one should be cautious when interpreting paediatric Bispectral Index data.

Cardiorespiratory variables, bispectral index and recovery of anesthesia in dogs anesthetized with isoflurane, treated or not with tramadol

It was studied fortuitous cardiorespiratory and bispectral index changes in dogs anesthetized with isoflurane associated or not to tramadol. Sixteen dogswere distributed in two groups named CG (control group) and TG (tramadol group). General anesthesia was induced in all animals with isoflurane via mask. After 10 minutes, the animals of CG received 0.05ml/kg of saline solution at 0.9%, and TG received 2mg/kg of tramadol, both via intramuscular. It was evaluated heart rate, systolic, diastolic and mean arterial pressures; electrocardiography; respiratory rate; oxihemoglobin saturation; end tidal carbon dioxide; bispectral index and recovery of anesthesia. The administration of tramadol in dogs anesthetized with isoflurane did not produce changes in cardiorespiratory variables, bispectral index and anesthetic recovery time. In addition, this association promoted good quality of anesthetic recovery.

Differential electroencephalographic response to tracheal intubation between young and elderly during isoflurane– and sevoflurane–nitrous oxide anaesthesia

Age-associated differences in the electroencephalographic (EEG) response to noxious stimuli with the presence of nitrous oxide (N(2)O) are unknown. We compared the EEG response with tracheal intubation between young and elderly. Sixty young (<40 yr) and elderly (>70 yr) patients were randomly allocated to one of the four groups. Anaesthesia was induced with 66% N(2)O and isoflurane in oxygen (Young-isoflurane and Elderly-isoflurane groups) or 66% N(2)O and sevoflurane in oxygen (Young-sevoflurane and Elderly-sevoflurane groups). Inhaled isoflurane and sevoflurane concentrations were gradually increased and the end-tidal concentrations were maintained at 1.1% and 1.7%, respectively. Tracheal intubation was performed 12 min after induction of anaesthesia. There were significant differences in the overall changes in bispectral index (BIS) and 95% spectral edge frequency (SEF95) between young and elderly (P<0.001 for both), but not between patients receiving isoflurane and sevoflurane (P=0.4 and 0.3, respectively). Both BIS and SEF95 were significantly decreased after tracheal intubation in Young-isoflurane and Young-sevoflurane groups (P<0.05 for all). In sharp contrast, BIS and SEF95 remained unchanged in Elderly-isoflurane and Elderly-sevoflurane groups (P>0.7 for all). These results suggest that both BIS and SEF95 significantly decreased, despite the presence of increased sympathetic activity after tracheal intubation in young patients. A significant difference was detected in EEG response to tracheal intubation between young and elderly. BIS does not reflect the depth of anaesthesia after tracheal intubation during anaesthesia with isoflurane or sevoflurane with 66% of N(2)O in young patients.

Effects of epidural administration of dexmedetomidine on the minimum alveolar concentration of isoflurane in dogs

Objective-To evaluate the effects of epidural administration of 3 doses of dexmedetomidine on isoflurane minimum alveolar concentration (MAC) and characterize changes in bispectral index (BIS) induced by nociceptive stimulation used for MAC determination in dogs. Animals-6 adult dogs. Procedures-Isoflurane-anesthetized dogs received physiologic saline (0.9% NaCl) solution (control treatment) or dexmedetomidine (1.5 [DEX1.5], 3.0 [DEX3], or 6.0 [DEX6] mug/kg) epidurally in a crossover study. Isoflurane MAC (determined by use of electrical nociceptive stimulation of the hind limb) was targeted to be accomplished at 2 and 4.5 hours. Changes in BIS attributable to nociceptive stimulation and cardiopulmonary data were recorded at each MAC determination. Results-With the control treatment, mean +/- SD MAC values did not change over time (1.57 +/- 0.23% and 1.55 +/- 0.25% at 2 and 4.5 hours, respectively). Compared with the control treatment, MAC was significantly lower at 2 hours (13% reduction) but not at 4.5 hours (7% reduction) in DEX1.5-treated dogs and significantly lower at 2 hours (29% reduction) and 4.5 hours (13% reduction) in DEX3-treated dogs. The DEX6 treatment yielded the greatest MAC reduction (31% and 22% at 2 and 4.5 hours, respectively). During all treatments, noxious stimulation increased BIS; but changes in BIS were correlated with increases in electromyographic activity. Conclusions and Clinical Relevance-In dogs, epidural administration of dexmedetomidine resulted in dose-dependent decreases in isoflurane MAC and that effect decreased over time. Changes in BIS during MAC determinations may not represent increased awareness because of the possible interference of electromyographic activity.

Hemodynamic and bispectral index changes following skull pin attachment with and without local anesthetic infiltration of the scalp

We studied the hemodynamic and bispectral index (BIS) changes in 44 patients undergoing cervical diskectomy with attachment of a Gardner-Wells tong (with two sharp conical pins) to the skull to facilitate intraoperative bone graft insertion. Patients were induced with fentanyl, thiopentone, and rocuronium and maintained with 66% nitrous oxide and 0.5% isoflurane, Before insertion of the pins, patients were randomly allocated to have either saline or lidocaine infiltration of the scalp at the proposed pin sites. Two minutes later, the pins were driven into the scalp. The BIS, mean arterial pressure (MAP), and heart rate (HR) were recorded before (baseline) and at 30, 60, 90, and 120 s after pin insertion. Data were compared with the baseline values and between the groups. A significant increase in MAP and HR occurred throughout the study period in the saline group. Skull pinning increased BIS throughout the study period in the saline group only, with maximal increases observed at 90 and 120 s (66.1 +/- 6.3 at 90 s and 65.7 +/- 6.4 at 120 s versus a baseline value of 62 +/- 8, P < 0.001). The increase in BIS was significant in the saline group compared with the lidocaine group at each time point. In conclusion, increases in MAP, HR, and BIS produced by skull pinning were prevented by prior local anesthetic infiltration.

Effect of Intravenous Propofol and Fentanyl on Bispectral Index Changes during Endotracheal Suction in ICU Conscious Patient

Background: We performed a prospective, randomized, and controlled trial to evaluate the effect of an intravenous fentanyl and propofol on the variation in BIS level associated tracheal suction. Methods: Thirty ICU patients intubated or tracheostomized were randomly allocated to control and experimental groups. Control group was received saline and experimental groups were received propofol with or without fentanyl intravenously prior to tracheal suction. And then we monitored BIS index, blood pressure, heart rate and SpO2 before, during and after tracheal suction. Results: BIS index was significantly lower in propofol plus fentanyl group than others during experiment (P ＜ 0.05). Heart rate and blood pressure in propofol plus fentanyl group also less increased than those in control or propofol group during tracheal suction (P ＜ 0.05). Conclusions: These results suggest that co-administration of propofol and fentanyl has more effective than propofol alone in sedation and analgesia of ICU patients during tracheal suction. (Korean J Anesthesiol 2007; 52: 156~60)

Effect of Nicardipine on Haemodynamic and Bispectral Index Changes following Endotracheal Intubation

We investigated the effect of IV nicardipine on haemodynamic and bispectral index responses to the induction of general anaesthesia and intubation. Forty patients were randomly allocated to two groups of 20 to receive normal saline or nicardipine 15 microg/kg IV 30 s after induction. Ninety seconds later, tracheal intubation was performed. Systolic blood pressure, heart rate and bispectral index were measured at baseline, 1 min after induction, pre-intubation, and every minute until 5 min after endotracheal intubation. Rate-pressure product values were calculated. In the nicardipine group, systolic blood pressure decreased compared with the control group, and heart rate increased comparedwith the control group. Bispectral index and rate-pressure product showed no differences between the two groups. In conclusion, the administration of 15 microg/kg nicardipine IV does not affect anaesthetic depth in response to the induction of general anaesthesia and intubation.