Effect-site Concentration Of Propofol Research Articles

Relationship between preinduction electroencephalogram patterns and propofol sensitivity in adult patients.

To determine the precise induction dose, an objective assessment of individual propofol sensitivity is necessary. This study aimed to investigate whether preinduction electroencephalogram (EEG) data are useful in determining the optimal propofol dose for the induction of general anesthesia in healthy adult patients. Seventy healthy adult patients underwent total intravenous anesthesia (TIVA), and the effect-site target concentration of propofol was observed to measure each individual's propofol requirements for loss of responsiveness. We analyzed preinduction EEG data to assess its relationship with propofol requirements and conducted multiple regression analyses considering various patient-related factors. Patients with higher relative delta power (ρ = 0.47, p < 0.01) and higher absolute delta power (ρ = 0.34, p = 0.01) required a greater amount of propofol for anesthesia induction. In contrast, patients with higher relative beta power (ρ = -0.33, p < 0.01) required less propofol to achieve unresponsiveness. Multiple regression analysis revealed an independent association between relative delta power and propofol requirements. Preinduction EEG, particularly relative delta power, is associated with propofol requirements during the induction of general anesthesia. The utilization of preinduction EEG data may improve the precision of induction dose selection for individuals.

Effect of Remimazolam Supplementation on Propofol Requirements During Hysteroscopy: A Double-Blind, Dose-Response Study.

Propofol is commonly used for procedural sedation but may increase side effects in a dose-dependent manner. Remimazolam, an ultrashort-acting benzodiazepine, has been approved for procedural sedation but may delay awakening. This study tested the hypothesis that remimazolam as a supplement reduces effect-site propofol concentration (Ceprop) required to suppress response to cervical dilation in patients undergoing hysteroscopy. One hundred and fifty patients who were scheduled for hysteroscopy were randomized to receive 0, 0.05, 0.1, 0.15, or 0.2 mg·kg-1 intravenous remimazolam, followed by a bolus of sufentanil 0.15 μg⋅kg-1, and a target-controlled propofol infusion. The initial target Ceprop was 3.5 μg·mL-1 and was increased or decreased in subsequent patients by steps of 0.5 μg·mL-1 according to whether there was loss of response to cervical dilation in the previous patient. We used up-down sequential analysis to determine values of Ceprop that suppressed response to cervical dilation in 50% of patients (EC50). The EC50 of propofol for suppressing response to cervical dilation was lower in patients given 0.1 mg·kg-1 (2.08 [95% confidence interval, CI, 1.88-2.28] μg·mL-1), 0.15 mg⋅kg-1 (1.83 [1.56-2.10] μg·mL-1), and 0.2 mg⋅kg-1 (1.43 [1.27-1.58] μg·mL-1) remimazolam than those given 0 mg⋅kg-1 (3.67 [3.49-3.86] μg·mL-1) or 0.05 mg⋅kg-1 (3.47 [3.28-3.67] μg·mL-1) remimazolam (all were P < .005). Remimazolam at doses of 0.1, 0.15, and 0.2 mg·kg-1 decreased EC50 of propofol by 43.3% (95% CI, 41.3%-45.5%), 50.3% (48.0%-52.8%), and 61.2% (58.7%-63.8%), respectively, from baseline (remimazolam 0 mg⋅kg-1). Propofol consumption was lower in patients given 0.1 mg⋅kg-1 (4.15 [3.51-5.44] mg·kg-1), 0.15 mg⋅kg-1 (3.54 [3.16-4.46] mg·kg-1), and 0.2 mg⋅kg-1 (2.74 [1.73-4.01] mg·kg-1) remimazolam than those given 0 mg⋅kg-1 (6.09 [4.99-7.35] mg·kg-1) remimazolam (all were P < .005). Time to anesthesia emergence did not differ significantly among the 5 groups. For women undergoing hysteroscopic procedures, remimazolam at doses from 0.1 to 0.2 mg·kg-1 reduced the EC50 of propofol inhibiting response to cervical dilation and the total propofol requirement. Whether the combination could improve perioperative outcomes deserves further investigation.

Effect of remifentanil on three effect-site concentrations of propofol and their relationship during electroencephalography at loss of response, at maximum alpha power, and at onset of burst suppression: a prospective randomized trial.

The effect-site concentration (Ce) at loss of response (Ce-LOR) to propofol closely correlates both with Ce as electroencephalographic alpha power becomes highest (Ce-alpha) and with Ce at onset of burst suppression (BS) (Ce-OBS), when no opioids are administered. Co-administration of opioids dose-dependently decreases Ce-LOR. We investigated the influence of remifentanil on the relationship between these three Ces. After receiving approval from our local ethical committee, with written informed consent, we enrolled 90 participants (ASA-PS I or II) who were scheduled for elective surgery. Participants were randomly assigned to three groups: constant remifentanil Ce 0ng/ml (Remi_0); 1ng/mL (Remi_1); and 2ng/mL (Remi_2). We recorded both raw EEG and EEG-derived parameters on a computer. After reaching remifentanil equilibrium, we administered propofol using a target-controlled infusion pump such that propofol Ce increased to about 0.3μg/mL/min. After determining Ce-LOR, we administered 0.6mg/kg of rocuronium and started mask ventilation. The study protocol ended after observation of BS. Three participants were excluded. Ce-LOR in each group (Remi_0, Remi_1, Remi_2) was 2.00 ± 0.58μg/mL, 1.43 ± 0.49μg/mL, and 1.37 ± 0.42μg/mL. Ce-alpha was 2.91 ± 0.63μg/mL, 2.30 ± 0.41μg/mL, and 2.12 ± 0.39μg/mL. Ce-OBS was 3.80 ± 0.69μg/mL, 3.25 ± 0.68μg/mL, and 2.90 ± 0.57μg/mL. In three other instances, Ce was decreased by remifentanil. Generalized linear model analysis revealed that remifentanil had no influence on the relationship between the three Ces. During propofol anesthesia, even low concentrations of remifentanil shifted concentration-related electroencephalographic changes.

Propofol EC50 for inducing loss of consciousness in patients under combined epidural-general anesthesia or general anesthesia alone: a randomized double-blind study.

Combined epidural-general anesthesia (GA + EA) has been recommended as a preferred technique for both thoracic and abdominal surgery. The epidural anesthesia on the general anesthetic (GA) requirements has not been well investigated. Therefore, we conducted the present study to explore the predicted effect-site concentration of propofol (Ceprop) required for achieving the loss of consciousness (LOC) in 50% of patients (EC50) with or without epidural anesthesia. Sixty patients scheduled for gastrectomy were randomized into the GA + EA group or GA alone group to receive general anesthesia alone. Ropivacaine 0.375% was used for epidural anesthesia to achieve a sensory level of T4 or above prior to the induction of general anesthesia. The EC50 of predicted Ceprop for LOC was determined by the up-down sequential method. The consumption of anesthetics, emergence time from anesthesia, and postoperative outcomes were also recorded and compared. The EC50 of predicted Ceprop for LOC was lower in the GA + EA group than in the GA alone group [2.97 (95% CI: 2.63-3.31) vs. 3.36 (95% CI: 3.19-3.53) μg mL-1, (p = 0.036)]. The consumption of anesthetics was lower in the GA + EA group than in the GA alone group (propofol: 0.11 ± 0.02 vs. 0.13 ± 0.02 mg kg-1 min-1, p = 0.014; remifentanil: 0.08 ± 0.03 vs. 0.14 ± 0.04 μg kg-1 min-1, p < 0.001). The emergence time was shorter in the GA + EA group than in the GA alone group (16.0 vs. 20.5 min, p = 0.013). Concomitant epidural anesthesia reduced by 15% the EC50 of predicted Ceprop for LOC, decreased the consumptions of propofol and remifentanil during maintenance of anesthesia, and fastened recovery from anesthesia. ClinicalTrials.gov, identifier: NCT05124704.

Total Intravenous Anesthesia Protocol for Decreasing Unacceptable Movements during Cerebral Aneurysm Clipping with Motor-Evoked Potential Monitoring: A Historical Control Study and Meta-Analysis.

Injury can occur during intraoperative transcranial motor-evoked potential (MEP) monitoring caused by patient movement related to insufficient neuromuscular blocking agent use. Here, we evaluated the incidence of unacceptable movements in patients undergoing intraoperative MEP monitoring following our anesthetic protocol. We reviewed the anesthesia records of 419 patients who underwent unruptured cerebral aneurysm clipping with intraoperative MEP monitoring. The anesthetic protocol included target-controlled infusion with a fixed effect-site propofol concentration of 3 μg/mL and an adjustable effect-site remifentanil concentration of 10-12 ng/mL. We compared our findings of the intraoperative parameters and incidence of spontaneous movement and respiration with those of published meta-analysis studies. Spontaneous movement and respiration occurred in one (0.2%) patient each. The meta-analysis included six studies. The pooled proportions of spontaneous movement and respiration were 6.9% (95% confidence interval [CI], 1.3-16.5%) and 4.1% (95% CI, 0.5-14.1%), respectively. The proportion of spontaneous movement in our study was significantly lower than that in previous studies (p = 0.013), with no significant difference in spontaneous respiration (p = 0.097). Following our center's anesthesia protocol during cerebral aneurysm clipping resulted in a low incidence of spontaneous respiration and movement, indicating its safety for patients undergoing intraoperative MEP monitoring.

Effects of Remimazolam Anesthesia with Two Induction Doses on Hemodynamics and Recovery Profile in Older Patients: Comparison with Propofol Anesthesia.

Remimazolam has advantages such as hemodynamic stability and rapid onset. We investigated the effects of induction doses on hemodynamics and recovery profiles for remimazolam compared to propofol in older patients. Sixty-nine patients aged >65 years were randomly assigned to either the propofol anesthesia group (P group) or the remimazolam anesthesia group with an induction dose of 6 mg/kg/h (R6 group) or 12 mg/kg/h (R12 group), followed by 1 mg/kg/h. P group was anesthetized with 4 µg/mL of propofol effect-site concentration (Ce) with target-control infusion, followed by 2.5-3 µg/mL of Ce. The primary outcome was the difference between the baseline mean arterial pressure (MAP) and the lowest MAP during anesthesia (ΔMAP). ΔMAP was comparable between the P, R6, and R12 groups (43.8 ± 13.8 mmHg, 39.2 ± 14.3 mmHg, and 39.2 ± 13.5 mmHg, p = 0.443). However, the frequencies of vasoactive drug use were 54.5%, 17.4%, and 30.4% (p = 0.029), and the median doses of ephedrine 3 (0-6) mg, 0 (0-0) mg, and 0 (0-0) mg (p = 0.034), which were significantly different. This study showed remimazolam anesthesia with an induction dose of 6 mg/kg/h, rather than 12 mg/kg/h, could reduce the requirement for vasoactive drugs compared to propofol anesthesia.

Variability of predicted propofol concentrations and measured sevoflurane concentrations during general anaesthesia: a single-centre retrospective cohort study

BackgroundVariability is high in predicted propofol concentrations during clinical anaesthesia titrated by target-controlled infusion (TCI) to maintain a processed EEG parameter (bispectral index [BIS]) within a specified range. We have shown that the potential for improving the pharmacokinetic model is minimal. The drug titration paradox revealed that titration challenges the classical relationship between drug dose and effect in both individuals and the population. We hypothesised that dynamic factors during surgery beyond the static genetic, epigenetic, and other factors such as age, height, and weight affect the necessary dose. We compared the variability of measured end-tidal sevoflurane concentrations with predicted effect-site propofol concentrations when titrated to a BIS range of 40–60, with the hypothesis that the variability in measured sevoflurane concentrations would not be less than the variability in estimated propofol concentrations. MethodsClinical data from 2280 surgical procedures >1 h in duration were included in the analysis. Anaesthesia with sevoflurane or propofol was based on an institutional protocol. The titration performance for both drugs was assessed by comparing BIS values 30 min after skin incision. The variability of the required concentrations at the same time point was calculated and compared. ResultsThe achieved 30-min post-incision BIS ranges were not significantly different for sevoflurane or propofol TCI (30 [99% CI: 28–33] and 31 [99% CI: 27–36], respectively). The variability of sevoflurane concentrations was not significantly different from measured predicted propofol concentrations during BIS-guided anaesthesia (normalized concentration range of 0.89 [99% CI: 0.78–0.99] and 0.93 [99% CI 0.87–1.02). ConclusionsImprovements in prediction accuracy of pharmacokinetic models beyond that of those already in clinical use are unlikely to reduce variability in target anaesthetic concentrations across patients in clinical practice.

Does Propofol Effect Site (Brain) Concentration Predicted by Target-Controlled Infusion Correlate with Propofol Measured in the Brain? An Exploratory Study in Neurosurgical Patients

Total intravenous anesthesia with propofol can be administered by target-controlled infusion pumps, which work on the principles of pharmacokinetic modeling. While designing this model, neurosurgical patients were excluded as the surgical site and drug action site remained the same (brain). Whether the predicted set propofol concentration and the actual brain site concentration correlate, especially in neurosurgical patients with impaired blood-brain barrier (BBB), is still unknown. In this study we compared the set propofol effect-site concentration in the target-controlled infusion pump with actual brain concentration measured by sampling the cerebrospinal fluid (CSF). Consecutive adult neurosurgical patients requiring propofol infusion intraoperatively were recruited. Blood and CSF samples were collected simultaneously when patients received propofol infusion at 2 different target effect-site concentrations-2 and 4 ug/mL. To study BBB integrity, CSF-to-blood albumin ratio and imaging findings were compared. The propofol level in the CSF was compared with set concentration using the Wilcoxon signed-rank test. Fifty patients were recruited, and the data were analyzed from 43 patients. There was no correlation between propofol concentration set in TCI and propofol concentration measured in blood and CSF. Though imaging findings were suggestive of BBB disruption in 37/43 patients, the mean (±standard deviation) CSF-to-serum albumin ratio was 0.0028 ± 0.002, suggesting intact BBB integrity (ratio >0.3 was considered as disrupted BBB). CSF propofol level did not correlate with set concentration in spite of acceptable clinical anesthetic effect. Also, the CSF-to-blood albumin measurement did not provide information on the BBB integrity.

Density Spectral Array Enables Precise Sedation Control for Supermicrosurgical Lymphaticovenous Anastomosis: A Retrospective Observational Cohort Study.

Supermicrosurgical lymphaticovenous anastomosis (LVA) is a minimally invasive surgical technique that creates bypasses between lymphatic vessels and veins, thereby improving lymphatic drainage and reducing lymphedema. This retrospective single-center study included 137 patients who underwent non-intubated LVA in southern Taiwan. A total of 119 patients were enrolled and assigned to two study groups: the geriatric (age ≥ 75 years, n = 23) and non-geriatric groups (age < 75 years, n = 96). The primary outcome was to investigate and compare the arousal and maintenance of the propofol effect-site concentration (Ce) using an electroencephalographic density spectral array (EEG DSA) in both groups. The results showed that the geriatric group required less propofol (4.05 [3.73-4.77] mg/kg/h vs. 5.01 [4.34-5.92] mg/kg/h, p = 0.001) and alfentanil (4.67 [2.53-5.82] μg/kg/h vs. 6.68 [3.85-8.77] μg/kg/h, p = 0.047). The median arousal Ce of propofol among the geriatric group (0.6 [0.5-0.7] μg/mL) was significantly lower than that in patients aged ≤ 54 years (1.3 [1.2-1.4] μg/mL, p < 0.001), 55-64 years (0.9 [0.8-1.0] μg/mL, p < 0.001), and <75 years (0.9 [0.8-1.2] μg/mL, p < 0.001). In summary, the combined use of EEG DSA provides the objective and depth of adequate sedation for extensive non-intubated anesthesia in late-elderly patients who undergo LVA without perioperative complications.

Comparison of Half-Effective Concentration of Propofol in Patients with Parkinson's Disease and Non-Parkinson's Disease.

This study aimed to compare the half-effective concentration (EC50) of propofol required for the bispectral index (BIS) 50 in patients with Parkinson's disease (PD) and non-PD (NPD) during induction by the Dixon's improved sequential method. This prospective study recruited 20 patients with PD undergoing deep brain stimulation and 20 patients with NPD accompanied by meningioma or glioma undergoing intracranial surgery from March 2018 to March 2019. The patients were induced by propofolviatarget-controlledinfusion. The targeteffect-siteconcentrationof propofol was determined by the Dixon's improved sequential method. The results of the pilot experiment showed that the targeteffect-site concentration for the first patient with PD and NPD was 3.5 µg/mL and 2.8 µg/mL, respectively. BIS values were recorded after achievingaconstanteffect-siteconcentrationof propofol. The increment or decrement of the targeteffect-site concentration of the next patient was 0.1 µg/mL. Demographic data, general physical condition, and hemodynamic values were similar between the PD and the NPD groups. The targeteffect-siteconcentrationof propofol induction doses was significantly higher in the PD group than in the NPD group. The EC50 of propofol required for BIS 50 was 3.213 µg/mL [95% confidence interval (CI), 3.085-3.287 µg/mL] in the PD group and 2.77 µg/mL (95% CI, 2.568-2.977 µg/mL) in the NPD group. The EC50 of propofol required for BIS 50 was higher in patients with PD than in patients with NPD.

Effect of neoadjuvant chemotherapy on effect-site concentration of propofol for sedation in patients with breast cancer.

Some studies have demonstrated that chemotherapy drugs enhance sensitivity to anesthetics owing to its systemic toxicity, while others have demonstrated that chemotherapy drugs have no effect. This study aimed to determine whether neoadjuvant chemotherapy influences the effect-site concentration (Ce) of propofol for sedation in patients withbreast cancer. This study included patients aged 19-75 years who were scheduled to undergobreast cancer surgery under general anesthesia. Patients who received neoadjuvant chemotherapy were assigned to group C, whereas those who never received chemotherapy wereassigned to group N. Propofol was administered through an effect-site target-controlled infusion, and the Modified Observer's Assessment of Alertness/Sedation scale (MOAA/S) scoreand Bispectral Index (BIS) were recorded. When the plasma concentration and Ce wereequal to the target Ce, and if the MOAA/S score did not change, the target Ce was increasedby 0.2 μg/ml; otherwise, the Ce was maintained for 2 min and then increased. This processwas repeated until the MOAA/S score became 0. No significant differences were observed in Ce values at each sedation level between both groups. Ce values for loss of consciousness (LOC) of groups C and N were 2.76± 0.29 and 2.67 ± 0.27 μg/ml (P = 0.285), respectively. However, the BIS value at LOC ofgroup C (63.87 ± 7.04) was lower than that (68.44 ± 6.01) of group N (P = 0.018). Neoadjuvant chemotherapy for breast cancer has no effect on the Ce ofpropofol for sedation.

Multiple sinus pauses during suspension laryngoscopy with external laryngeal manipulation in hyperextended neck position in a patient with enlarged cervical lymph nodes: a case report

Suspension laryngoscopy is a commonly performed procedure for effective laryngeal microsurgery (LMS). Although it is associated with few adverse events, cardiac complications such as severe arrhythmia induced by exaggerated vagal tone may arise during this procedure. Here, I present the case of a 52-year-old female patient who presented with a suspected thyroid follicular neoplasm and enlarged cervical lymph nodes. LMS was planned to remove a vocal fold polyp before the thyroid surgery. The patient was placed in a Boyce-Jackson position, and suspension laryngoscopy was performed. However, several sinus pauses were detected whenever external laryngeal manipulation (ELM) was performed to improve surgical field exposure, which was presumed to be attributed to vagal stimulation or reflex induced by numerous external and internal factors during laryngeal manipulation. The suspected mechanism was the direct stimulation of the vagus nerve termed the laryngo-cardiac reflex, or carotid sinus reflex, a type of baroreceptor reflex. When the first episode of sinus pause occurred, the effect-site target concentration of propofol was unadjusted after checking the bispectral index level indicating an adequate anesthetic depth, but ELM was discontinued. When the second episode occurred, ELM could not be stopped until good laryngeal visualization was achieved. Then, the patient received 0.2 mg of intravenous glycopyrrolate. Her heart rate returned within the normal range whenever ELM was not applied. When performing suspension laryngoscopy, the head and neck positioning, the procedure itself and laryngeal manipulation may act as external factors that could induce an exaggerated vagal response. Further, patients with head and neck tumors have various internal factors, such as tumor itself, cervical lymphadenopathy or post-irradiation fibrosis, which can affect the carotid sinus and deteriorate the vagal response. Therefore, careful preoperative evaluation is required to identify these internal factors in advance and take proper care to minimize the additional influence of external factors.

High daily caffeine intake is associated with lower propofol requirements for anesthetic induction.

There is significant interindividual variation in the dose of propofol required for anesthetic induction. Factors dictating this are poorly described, but understanding them would be useful for anesthetic drug dosing. It has been shown in rats and recently in humans that caffeine administration accelerates recovery from anesthesia, but no study has assessed the effect on anesthetic induction. Forty American Society of Anesthesiologists (ASA)-I, 18-65-year-old patients, undergoing day case general anesthesia with propofol and fentanyl took part in this observational study. Total daily caffeine intake (mg) was estimated using the caffeine assessment tool and caffeine content values from the US Department of Agriculture National Nutrient Database. Pharmacokinetic-pharmacodynamic modeling was used to estimate the effect site concentration of propofol at loss of consciousness (Ce(p) LOC). Median (interquartile range [IQR]) daily caffeine intake was 106 (51-193) mg. Ce(p) LOC was lower in those with caffeine intake greater than or equal to the median of 106 mg (median (IQR) = 0.64 μg/ml (0.51-0.72) vs. 0.70 μg/ml (0.57-1.10), P = 0.04). The effect was robust when controlling for weight-adjusted fentanyl dose, age, smoking status, and alcohol intake (F (1,34) = 4.66, P = 0.04). High daily caffeine intake is associated with lower propofol requirements for day case anesthetic induction. We propose that high daily caffeine intake may cause lower arousal levels prior to surgery due to a relative caffeine deficit caused by being nil by mouth. As such, assessment of daily caffeine intake preoperatively may aid anesthetic drug dosing.

Optimal Propofol Concentration at Effect Site for Esophagogastroduodenoscopy under Moderate to Deep Sedation with Target-controlled Infusion

Background: The target-controlled infusion (TCI) of propofol is being increasingly used for moderate-to-deep sedation during esophagogastroduodenoscopies (EGDs). Objective: To determine the target effect-site concentration (Cet) of propofol required for EGD scope insertions during sedation using TCI. Materials and Methods: Dixon’s up-and-down sequential allocation method was used with patients scheduled for elective EGD at Srinagarind Hospital, Thailand. The patients were divided into Group A aged 18 to 64 years and Group B aged over 65 years. Anesthesia was induced with propofol via TCI (Schnider model). The propofol Cet commenced at 3 mcg/mL and 2 mcg/mL in Groups A, and B, respectively. The response during an EGD scope insertion determined the Cet for the next patient, with intervals of 0.3 mcg/mL. Calculations of the effective concentration without response during EGD scope insertion in 50% and 95% of patients (EC50 and EC95) values of propofol, with 95% confidence intervals (CIs), were performed using the isotonic regression method. Results: Twenty-one and nineteen patients were enrolled in Groups A, and B, respectively. In Group A, the EC50 of propofol for EGD was 3.30 mcg/mL (95% CI 3.05 to 3.55), while the EC95 was 3.75 mcg/mL (95% CI 3.34 to 4.16). In the case of Group B, the EC50 was 3.05 mcg/mL (95% CI 2.75 to 3.35) and the EC95 was 3.05 mcg/mL (95% CI 2.92 to 3.18). Hypotension occurred in 52.3% and 31.5% of patients in group A, and B, respectively. Conclusion: The appropriate Cet of propofol for anesthesia during EGD using TCI is 3.75 mcg/mL for patients aged 18 to 64 years, and 3.05 mcg/mL for patients aged 65 years and over. Hypotension is the most common adverse event of moderate-to-deep sedation with propofol using TCI. Keywords: Sedation; Esophagogastroduodenoscopy; Propofol; Target-controlled infusion

Influence of body fatness on propofol requirements for loss of consciousness in target-controlled infusion: A STROBE-compliant study.

This prospective observational study evaluated the effects of body fat on the pharmacologic effect of propofol. Hundred patients aged 18 to 75 years who were scheduled to undergo orthopedic surgery under regional block were enrolled. All participants underwent bioelectrical impedance analysis and were allocated into 2 groups: the high and normal adiposity group, according to percent body fat. Following successful regional block, propofol was incrementally infused until loss of consciousness (LOC) with a target-controlled infusion pump. The effect-site concentration of propofol at LOC and the total infused dose of propofol per total body weight until LOC were recorded. At the end of the surgery, the infusion of propofol was stopped. The elapsed time to recovery of consciousness (ROC) and the effect-site concentration at ROC were recorded. These pharmacologic data were compared between 2 groups. The effect-site concentration of propofol at LOC (µg/mL) was significantly lower in the high adiposity group than in the normal group in both sexes (3.5 ± 0.4 vs 3.9 ± 0.6; P = .020 in males, and 3.4 [interquartile range: 2.9–3.5] vs 3.8 [interquartile range: 3.3–3.9]; P = .006 in females). Total dose per total body weight until LOC (mg/kg) were also significantly lower in the high adiposity group than in the normal group. There was no significant difference in the data related to ROC. The pharmacologic effects of propofol may be affected by the composition of body components. The concentration of propofol using a target-controlled infusion system may be diminished in patients with a high proportion of body fat.

The effect of age on electroencephalogram measures of anesthesia hypnosis: A comparison of BIS, Alpha Power, Lempel-Ziv complexity and permutation entropy during propofol induction

BackgroundImproving anesthesia administration for elderly population is of particular importance because they undergo considerably more surgical procedures and are at the most risk of suffering from anesthesia-related complications. Intraoperative brain monitors electroencephalogram (EEG) have proved useful in the general population, however, in elderly subjects this is contentious. Probably because these monitors do not account for the natural differences in EEG signals between young and older patients. In this study we attempted to systematically characterize the age-dependence of different EEG measures of anesthesia hypnosis.MethodsWe recorded EEG from 30 patients with a wide age range (19–99 years old) and analyzed four different proposed indexes of depth of hypnosis before, during and after loss of behavioral response due to slow propofol infusion during anesthetic induction. We analyzed Bispectral Index (BIS), Alpha Power and two entropy-related EEG measures, Lempel-Ziv complexity (LZc), and permutation entropy (PE) using mixed-effect analysis of variances (ANOVAs). We evaluated their possible age biases and their trajectories during propofol induction.ResultsAll measures were dependent on anesthesia stages. BIS, LZc, and PE presented lower values at increasing anesthetic dosage. Inversely, Alpha Power increased with increasing propofol at low doses, however this relation was reversed at greater effect-site propofol concentrations. Significant group differences between elderly patients (>65 years) and young patients were observed for BIS, Alpha Power, and LZc, but not for PE.ConclusionBIS, Alpha Power, and LZc show important age-related biases during slow propofol induction. These should be considered when interpreting and designing EEG monitors for clinical settings. Interestingly, PE did not present significant age differences, which makes it a promising candidate as an age-independent measure of hypnotic depth to be used in future monitor development.

SEDATION IN COLONOSCOPY: WHATTHE EFFECT-SITE CONCENTRATION OF PROPOFOL IN TARGET-CONTROLLED INFUSION FOR WHICH THE ACTBECAMECOMFORTABLE AT THE INTRODUCTION OF COLONOSCOPE?

Method: Prospective observational study carried out over 5 months, with the objective of determining the effect-site concentration of propofol in target-controlled infusion anesthesia which allows the introduction of a colonoscope under the best conditions.84 patients aged 18 to 71 are included: 38% were male and 46% female, with 57% classified as ASA I and 43% as ASA II. Results: Among the 84 patients: 47.6% had no history, 11.9% hypertensive, 14.3% diabetic, 21.4% dyslipidemic, 4.8% followed for stable heart failure. Reflex loss concentrations averaged 3.78 ug/mL with a minimum of 2.6 ug/mL and maximum of 4.8 ug/mL.While the target concentrations of the introduction of colonoscope which allows comfort for the gastroenterologist and the patient were on average 5.24 ug/mL with a minimum of 3.4 ug/mL and maximum of 6.8 ug/mL.

Effects of antipsychotics on intravenous sedation with midazolam and propofol during dental treatment for patients with intellectual disabilities.

Some patients with intellectual disabilities (ID) are prescribed antipsychotic drugs for symptomatic treatment of behavioural disorders. Nevertheless, it can still prove difficult to perform dental treatments safely for some patients with ID. In such cases, treatment under intravenous sedation (IVS) is one option. Sedative, hypnotic and α-blocking effects of antipsychotic drugs may cause adverse events, such as severe hypotension, among patients who take antipsychotic drugs regularly. This study aimed to investigate the effects of oral antipsychotic medication on cardiovascular function during IVS. Accordingly, we compared mean blood pressure (MBP) and heart rate (HR) between patients who regularly take antipsychotic drugs and patients who do not. Thirty-seven patients with ID were enrolled in this study. All participants were outpatients of Special Care Dentistry of general hospital and received dental treatment under IVS performed with a combination of midazolam and propofol. Eighteen patients regularly took antipsychotics (medication group), and 19 patients were not currently taking antipsychotics (non-medication group). MBP, HR, dose, and effect-site concentration of intravenous sedative medications were measured at three points: 'before IVS', 'at optimal sedation', and 'during dental treatment'. The magnitude of reduction of MBP was significantly smaller in the medication group than in the non-medication group (P<0.023). However, there were no differences in MBP, HR, dose, and effect-site concentration of midazolam and propofol between groups at any point. These results suggest that antipsychotic medication may not have clinically significant adverse effects on cardiovascular fluctuations during dental treatment under IVS for persons with ID.

The requirement of propofol for induction of anesthesia in patients with traumatic brain injury determined using bilateral bispectral index and target controlled infusion - An observational cohort study.

Patients with traumatic brain injury (TBI) frequently require emergency surgery. There is a paucity of literature with regard to anesthetic requirements in these patients. The aim of the study was to compare the dose of propofol required for induction of anesthesia in patients with different grades of TBI. This prospective, observational study included patients with mild, moderate, and severe grades of TBI undergoing emergency surgery within 48 h of injury. Bispectral Index (BIS) values were recorded using a bilateral BIS sensor. Anesthesia was induced with a target controlled infusion (TCI) pump. Once BIS reached 40, plasma (Cp) and effect-site (Ce) concentration and total dose of propofol required were noted from the TCI pump. Of the 96 patients recruited, 27, 36, and 33 patients belonged to mild, moderate, and severe TBI (sTBI) groups, respectively. The Ce of propofol in mild, moderate, and sTBI groups was 6 ± 0.9, 5.82 ± 0.98, and 4.48 ± 1.5 μg/mL (P < 0.001), and the dose of propofol required was 1.9 ± 0.2, 1.8 ± 0.4, 1.41 ± 0.5 mg/kg, respectively (P < 0.001). Baseline BIS on the injured side was 80 ± 7.8, 71 ± 9.4, 55 ± 11.6, and on the uninjured side was 89 ± 5.5, 81 ± 8.4, and 65 ± 12 in mild, moderate, and sTBI groups, respectively. The requirement of propofol was reduced in patients with sTBI. The dose of propofol required for induction of anesthesia as determined using Ce was significantly lower only between sTBI and mild TBI and not between patients with sTBI and moderate TBI or between mild and moderate head injury. BIS values were significantly different between the groups (highest in mild TBI and lowest in sTBI) and between normal and injured sides within each group.

Estimation of median effective effect-site concentration (EC50) during target-controlled infusion of propofol for dilatation and curettage - A prospective observational study.

Background and Aims:Propofol is the drug of choice for sedation in daycare procedures due to its pharmacokinetic properties. Propofol delivery using target-controlled infusion (TCI) pump reduces adverse effects like hypotension and apnoea. In this study, we estimated the median effective effect-site concentration of propofol in patients undergoing dilatation and curettage.Methods:Patients of the American Society of Anesthesiologists physical status class I–III, aged 40–70 years, undergoing elective dilatation and curettage were recruited for the study. All patients received 1 μg/kg fentanyl and 20 mg lignocaine. The first patient received an effect-site concentration of propofol at 4 μg/mL with TCI Schneider pharmacokinetic model. Failure was defined as patient movement at any time during the procedure. According to the ‘BiasedCoin Design’ up-and-down sequential method, the response of the previous patient determined the effect-site concentration of propofol of the next patient. The study was terminated once forty patients completed the procedures successfully. Probit analysis was used to determine EC50.Results:Fifty-three patients were recruited for the study. The various effect-site concentrations of propofol EC50, EC90, and EC95 in providing sedation for dilatation and curettage were 3.38 μg/mL, 4.29 μg/mL, and 4.60 μg/mL, respectively. The incidence of hypotension and apnoea were comparable among the various concentrations of propofol. The mean duration of the propofol infusion was 20 ± 2.86 min. The time to recovery from propofol sedation was 6.97 ± 1.76 min.Conclusion:A median effective effect-site concentration of 3.38 μg/mL of propofol is required to prevent patient movement during uterine dilatation and curettage.