Sensitivity to propofol in the elderly

Dynamic prediction of hypoxemia risk at different time points based on preoperative and intraoperative features: machine learning applications in outpatients undergoing esophagogastroduodenoscopy

BACKGROUND

Hypoxemia often occurs in outpatients undergoing anesthesia-assisted esophagogastroduodenoscopy (EGD). However, there is a scarcity in tools to predict the hypoxemia risk. We aimed to solve this problem by developing and validating machine learning (ML) models based on preoperative and intraoperative features.

METHODS

All data were retrospectively collected from June 2021 to February 2022. The most appropriate predictive features were selected by the least absolute shrinkage and selection operator, which were incorporated and modelled by 4 ML algorithms. The area under the precision-recall curve (AUPRC) was used as the main evaluation metric to select the best models, and the selected models were compared with the STOP-BANG score. Their predictive performance was visually interpreted by SHapley Additive exPlanations. The primary endpoint of this study was hypoxemia during the procedure, defined as at least one reading of pulse oximetry < 90% without probes misplacement from the anesthesia induction beginning to the end of EGD, while the secondary endpoint was hypoxemia during induction, from the induction beginning to the start of endoscopic intubation.

RESULTS

Of 1160 patients in the derivation cohort, 112 patients (9.6%) developed intraoperative hypoxemia, of which 102 (8.8%) occurred during the induction period. In temporal and external validation, no matter whether based on preoperative variables or still based on preoperative plus intraoperative variables, our models showed excellent predictive performance for the two endpoints, significantly better than STOP-BANG score. In the model interpretation section, preoperative variables (airway assessment indicators, pulse oximeter oxygen saturation and BMI) and intraoperative variables (the induced propofol dose) made the highest contribution to the predictions.

To our knowledge, our ML models were the first to predict hypoxemia risk, which achieved excellent overall predictive ability integrating various clinical indicators. These models have the potential to become an effective tool for adjusting sedation strategies flexibly and reducing the workload of anesthesiologists.KEY MESSAGESThis study is the first model employing ML methods based on preoperative and preoperative plus intraoperative variables for predicting the risk of hypoxemia during induction and the whole EGD procedure respectively.Our four models achieved satisfactory predictive performance and outperformed STOP-BANG score in terms of AUPRC in the temporal and external validation cohorts respectively.We found that the relevant variables of airway assessment should be fully taken into account when analyzing the risk factor of hypoxemia, and the effect of patients' age on their hypoxemia risk should be considered in conjunction with the propofol dose.

The effect of age on the induction dose of propofol for general anesthesia in dogs

OBJECTIVE

In people, the dose of propofol (DOP) required for procedural sedation and anesthesia decreases significantly with age. The objective of this study was to determine if the DOP required to perform endotracheal intubation decreases with age in dogs.

STUDY DESIGN

Retrospective case series.

ANIMALS

1397 dogs.

METHODS

Data from dogs anesthetized at referral center (2017-2020) were analyzed with three multivariate linear regression models with backward elimination using a combination of either absolute age, physiologic age, or life expectancy (ratio between age at the time of anesthetic event and expected age of death for each breed obtained from previous literature) as well as other factors as independent variables, and DOP as the dependent variable. The DOP for each quartile of life expectancy (<25%, 25-50%, 50-75%, 75-100%, >100%) was compared using one-way ANOVA. Significance was set at alpha = 0.025.

RESULTS

Mean age was 7.2 ± 4.1 years, life expectancy 59.8 ± 33%, weight 19 ± 14 kg, and DOP 3.76 ± 1.8 mg kg-1. Among age models, only life expectancy was a predictor of DOP (-0.37 mg kg-1; P = 0.013) but of minimal clinical importance. The DOP by life age expectancy quartile was 3.9 ± 2.3, 3.8 ± 1.8, 3.6 ± 1.8, 3.7 ± 1.7, and 3.4 ± 1.6 mg kg-1, respectively (P = 0.20). Yorkshire Terrier, Chihuahua, Maltese, mixed breed dogs under 10 kg, and Shih Tzu required higher DOP. Status of neutered male, ASA E, and Boxer, Labrador and Golden Retriever breeds decreased DOP, along with certain premedication drugs.

CONCLUSIONS AND CLINICAL RELEVANCE

In contrast to what is observed in people, an age cut-off predictive of DOP does not exist. Percentage of elapsed life expectancy along with other factors such as breed, premedication drug, emergency procedure, and reproductive status significantly alter DOP. In older dogs, the dose of propofol can be adjusted based on their elapsed life expectancy.

Permutation entropy is not an age-independent parameter for EEG-based anesthesia monitoring

Background

An optimized anesthesia monitoring using electroencephalographic (EEG) information in the elderly could help to reduce the incidence of postoperative complications. Processed EEG information that is available to the anesthesiologist is affected by the age-induced changes of the raw EEG. While most of these methods indicate a "more awake" patient with age, the permutation entropy (PeEn) has been proposed as an age-independent measure. In this article, we show that PeEn is also influenced by age, independent of parameter settings.

Methods

We retrospectively analyzed the EEG of more than 300 patients, recorded during steady state anesthesia without stimulation, and calculated the PeEn for different embedding dimensions m that was applied to the EEG filtered to a wide variety of frequency ranges. We constructed linear models to evaluate the relationship between age and PeEn. To compare our results to published studies, we also performed a stepwise dichotomization and used non-parametric tests and effect sizes for pairwise comparisons.

Results

We found a significant influence of age on PeEn for all settings except for narrow band EEG activity. The analysis of the dichotomized data also revealed significant differences between old and young patients for the PeEn settings used in published studies.

Conclusion

Based on our findings, we could show the influence of age on PeEn. This result was independent of parameter, sample rate, and filter settings. Hence, age should be taken into consideration when using PeEn to monitor patient EEG.

5-Aminolevulinic acid hydrochloride enhances bupivacaine-induced hypotension in spontaneously hypertensive rats

PURPOSE

Oral administration of 5-aminolevulinic acid hydrochloride (5-ALA-HCl) has been reported to enhance the hypotensive effects associated with anesthetics, especially in elderly hypertensive patients treated with antihypertensive agents. The present study aimed to clarify the effects of antihypertensive-agent- and anesthesia-induced hypotension by 5-ALA-HCl in spontaneously hypertensive rats (SHRs).

METHODS

We measured blood pressure (BP) of SHRs and normotensive Wistar Kyoto (WKY) rats treated with amlodipine or candesartan before and after administration of 5-ALA-HCl. We also investigated the change in BP following intravenous infusion of propofol and intrathecal injection of bupivacaine in relation to 5-ALA-HCl administration.

FINDINGS

Oral administration of 5-ALA-HCl significantly reduced BP in SHRs and WKY rats with amlodipine and candesartan. Infusion of propofol significantly reduced BP in SHRs treated with 5-ALA-HCl. Intrathecal injection of bupivacaine significantly declined SBP and DBP in both SHRs and WKY rats treated with 5-ALA-HCl. The bupivacaine-induced decline in SBP was significantly larger in SHRs compared with WKY rats.

CONCLUSION

These findings suggest that 5-ALA-HCl does not affect the antihypertensive agents-induced hypotensive effect, but enhances the bupivacaine-induced hypotensive effect, especially in SHRs, indicating that 5-ALA may contribute to anesthesia-induced hypotension via suppression of sympathetic nerve activity in patients with hypertension.

Depth of anaesthesia and mortality after cardiac or noncardiac surgery: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Recent randomised controlled trials have failed to show a benefit in mortality by using processed electroencephalography (pEEG) to guide lighter anaesthesia. We performed a meta-analysis of mortality data from randomised trials of pEEG monitoring to assess the evidence of any protective effect of pEEG-guided light anaesthesia compared with deep anaesthesia in adults aged ≥18 yr.

METHODS

Our study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. In February 2022, we searched three databases (Cochrane CENTRAL, OVID Medline, EMBASE) for RCTs of pEEG monitoring that provided mortality data at 30 days, 90 days, and/or 1 yr or longer.

RESULTS

We included 16 articles from 12 RCTs with 48 827 total participants. We observed no statistically significant mortality reduction with light anaesthesia compared with deep anaesthesia in patients aged ≥18 yr when all studies were pooled (odds ratio [OR]=0.99; 95% confidence interval (CI), 0.92-1.08). This result did not change significantly when analysing mortality at 30 days, 90 days, 1 yr or longer. We observed no mortality benefit for pEEG monitoring compared with usual care (OR=1.02; 95% CI, 0.89-1.18), targeting higher pEEG index values compared with lower values (OR=0.89; 95% CI, 0.60-1.32), or low pEEG index value alerts compared with no alerts (OR=1.02; 95% CI, 0.41-2.52).

CONCLUSIONS

pEEG-guided lighter anaesthesia does not appear to reduce the risk of postoperative mortality. The absence of a plausible rationale for why deeper anaesthesia should increase mortality has hampered appropriate design of definitive clinical trials.

CLINICAL TRIAL REGISTRATION

CRD42022285195 (PROSPERO).

Hypotension after general anesthesia induction using remimazolam in geriatric patients: Protocol for a double-blind randomized controlled trial

Introduction

In geriatric patients, hypotension is often reported after general anesthesia induction using propofol. Remimazolam is a novel short-acting sedative. However, the incidence of hypotension after general anesthesia induction using remimazolam in geriatric patients remains unclear. This study aims to compare the incidence of hypotension associated with remimazolam and propofol in patients aged ≥80 years.

Methods

This single-center, double-blind, randomized, two-arm parallel group, standard treatment-controlled, interventional clinical trial will include 90 patients aged ≥80 years undergoing elective surgery under general anesthesia who will be randomized to receive remimazolam or propofol for induction. The primary outcome is the incidence of hypotension after general anesthesia induction, occurring between the start of drug administration and 3 min after intubation. We define hypotension as mean blood pressure <65 mmHg. The primary outcome will be analyzed using the full analysis set. The incidence of hypotension in the two groups will be compared using the Mantel-Haenszel χ2 test. Subgroup analysis of the primary outcome will be performed based on the Charlson comorbidity index, clinical frailty scale, hypertension in the ward, and age. Secondary outcomes will be analyzed using the Fisher’s exact test, Student’s t test, and Mann–Whitney U test, as appropriate. Logistic regression analysis will be performed to explore the factors associated with the incidence of hypotension after anesthesia induction.

Discussion

Our trial will determine the efficacy of remimazolam in preventing hypotension and provide evidence on the usefulness of remimazolam for ensuring hemodynamic stability during general anesthesia induction in geriatric patients.

Trial registration

The study has been registered with UMIN Clinical Trials Registry (UMIN000042587), on June 30, 2021.

Moderate sedation by total intravenous remimazolam-alfentanil vs. propofol-alfentanil for third molar extraction: A prospective randomized controlled trial

Background

Oral dental treatment cause anxiety, fear, and physical stress. This study aimed to investigate the efficacy and safety of moderate sedation by remimazolam with alfentanil vs. propofol with alfentanil in third molar extraction.

Methods

This single-center, randomized, single-blind clinical trial included 100 adults who underwent third molar ambulatory extraction. All patients had continuous infusion of Alfentanil 0.2 μg/kg/min. Group remimazolam with alfentanil (group RA) had an induction dose of 80 μg/kg and maintenance dosage of 5 μg/kg/min. In group propofol with alfentanil (PA group), propofol was infused at an initial concentration of 1.8 μg/mL under target controlled infusion (TCI) mode and a maintenance concentration of 1.5 μg/mL. The incidence rates of adverse effects were recorded and compared. Depth of sedation was assessed using the modified observer alertness/sedation assessment (MOAA/S) and entropy index. Recovery characteristics were recorded and complications observed for next 24 h.

Results

The incident of adverse events 6 (12%) in the group RA was lower than the group PA 25 (50%) [Mean difference 0.136 (95%CI, 0.049–0.377); P &lt; 0.05], with no serious adverse events during the sedation procedure. The incidence of injection pain in group RA was significantly lower than that in group PA [4 vs. 26%, mean difference 0.119 (95%CI, 0.025–0.558); P = 0.004]. Before starting local anesthesia, the mean arterial pressure, heart rate, and respiratory rate of the PA group were lower than those of the RA group. None of the patients required further treatments for a decreased heart rate, blood pressure, or low SpO2. The rate of moderate sedation success was 100% in both groups. The MOAA/S score was similar between the groups indicating that the depth of sedation was effective. Group RA had significantly shorter recovery and discharge times than those of group PA.

Conclusions

Remimazolam with alfentanil is a safer and more effective alternative for ambulatory sedation and can reduce recovery and discharge time and the incidence of perioperative adverse events compare with propofol.

Clinical trial registration

http://www.chictr.org.cn/index.aspx, identifier: ChiCTR2200058106.

Comparing propofol anaesthesia guided by Bispectral Index monitoring and frontal EEG wave analysis with standard monitoring in laparoscopic surgery: protocol for the 'EEG in General Anaesthesia - More Than Only a Bispectral Index' Trial, a multicentre, double-blind, randomised controlled trial

INTRODUCTION

The use of Bispectral Index (BIS) monitors for assessing depth of sedation has led to a reduction in both the incidence of awareness and anaesthetic consumption in total intravenous anaesthesia. However, these monitors are vulnerable to artefacts. In addition to the processed number, the raw frontal electroencephalogram (EEG) can be displayed as a curve on the same monitor. Anaesthesia practitioners can learn to interpret the EEG in a short tutorial and may be quicker and more accurate thanBIS in assessing anaesthesia depth by recognising EEG patterns. We hypothesise that quality of recovery (QoR) in patients undergoing laparoscopic surgery is better, if propofol is titrated by anaesthesia practitioners able to interpret the EEG.

METHODS AND ANALYSIS

This is a multicentre, double-blind (patients and outcome assessors) randomised controlled trial taking place in four Swiss hospitals. Patients aged 18 years or older undergoing laparoscopic procedures with general anaesthesia using propofol and anaesthesia practitioners with more than 2 years experience will be eligible. The primary study outcome is the difference in QoR 24 hours after surgery. Secondary outcomes are propofol consumption, incidence of postoperative nausea and vomiting (PONV) and postoperative delirium.QoR and propofol consumption are compared between both groups using a two-sample t-test. Fisher's exact test is used to compare the incidences of PONV and delirium. A total of 200 anaesthesia practitioners (and 200 patients) are required to have an 80% chance of detecting the minimum relevant difference for the QoR-15 as significant at the 5% level assuming a SD of 20.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from all responsible ethics committees (lead committee: Ethikkommission Nordwest- und Zentralschweiz, 16 January 2021). The findings of the trial will be published in a peer-reviewed journal, presented at international conferences, and may lead to a change in titrating propofol in clinical practice.

TRIAL REGISTRATION NUMBER

www.

CLINICALTRIALS

gov:NCT04105660.

Observer's Assessment of Alertness/Sedation-based titration reduces propofol consumption and incidence of hypotension during general anesthesia induction: A randomized controlled trial

Administration of a single propofol bolus dose for anesthesia induction causes hypotension. We included 160 patients (74 males and 86 females; mean age, 42.4 ± 10.7 [range: 18-60] years) with the American Society of Anesthesiologists status I-II undergoing elective surgery under general anesthesia. Using simple randomization, the patients were divided into a conventional group (n = 80; received 2 mg/kg propofol at a rate of 250 mg/min) and titrated group (n = 80; received propofol at a rate of 1 mg/kg/min until the Observer's Assessment of Alertness/Sedation scale score reached 1 point). Fentanyl (4 µg/kg) and cisatracurium (0.2 mg/kg) were administered, as appropriate. Systolic blood pressure, diastolic blood pressure, mean blood pressure, and heart rate were recorded at different time points. Propofol consumption, hypotension, and other adverse events were recorded. All the patients were intubated without awareness. Compared with the conventional group, the titrated group showed more stable blood pressure (p < 0.05), as well as a lower decrease in systolic blood pressure, mean blood pressure at 1 and 3 min, and diastolic blood pressure at 1 min after propofol administration (p < 0.01). Moreover, compared with the conventional group, the titrated group showed a lower post-intubation hypotension incidence (9 vs. 19 cases; p = 0.04), as well as lower total propofol dosage and propofol dose per kilogram of body weight (93.57 ± 14.40 mg vs. 116.80 ± 22.37 mg and 1.73 ± 0.27 mg/kg vs. 2.02 ± 0.08 mg/kg, respectively, p < 0.01). Compared with conventional propofol usage, titrated propofol administration can reduce the incidence of hypotension and propofol consumption during anesthesia induction.

Variation in propofol induction doses administered to surgical patients over age 65

BACKGROUND/OBJECTIVES

Advanced age is associated with increased susceptibility to acute adverse effects of propofol. The present study aimed to describe patterns of propofol dosing for induction of general anesthesia before endotracheal intubation in a nationwide sample of older adults presenting for surgery.

DESIGN

Retrospective observational study using the Multicenter Perioperative Outcomes Group data set.

SETTING

Thirty-six institutions across the United States.

PARTICIPANTS

A total of 350,766 patients aged over 65 years who received propofol for general anesthetic induction and endotracheal intubation between 2014 and 2018.

INTERVENTION

None.

MEASUREMENTS

Total induction bolus dose of propofol administered.

RESULTS

The mean (SD) weight-adjusted propofol dose was 1.7 (0.6) mg/kg. The mean prevalent propofol induction dose exceeded the upper bound of what has been described as the typical geriatric dose requirement across every age category examined. The percent of patients receiving propofol induction doses above the described typical geriatric range was 64.8% (95% CI 64.6-65.0), varying from 73.8% among patients aged 65-69 to 45.8% among patients aged 80 and older.

CONCLUSION

The present study of a large multicenter cohort demonstrates that prevalent propofol dosing commonly falls above the published typically required dose range for patients aged ≥65 in nationwide anesthetic practice. Widespread variability in induction dose administration remains incompletely explained by known patient variables. The nature and clinical consequences of these unexplained dosing decisions remain important topics for further study. Observed discordance between expected and actual induction dosing raises the question of whether there should be reconsideration of widespread provider practice or, alternatively, whether what is published as the typical propofol induction dose range should be revisited.

Intraoperative Vitamin C Reduces the Dosage of Propofol in Patients Undergoing Total Knee Replacement

Purpose

Propofol is commonly used as an intravenous anesthetic in surgical patients. However, its usage is associated with adverse effects. Auxiliary medication can reduce the dose of intravenous anesthetics. Hence, we investigated whether vitamin C could lower propofol dosage in elderly patients undergoing total knee replacement surgery.

Patients and Methods

The trial was carried out in PLA General Hospital in Beijing, China. We enrolled patients aged ≥50 years who were undergoing unilateral total knee arthroplasty with total intravenous anesthesia combined with lumbar sciatic nerve block. The patients were randomly assigned to either the vitamin C (Vc) group (0.067 g/kg) or the control group (an equivalent dose of normal saline). Nerve block was done for all the patients before the general anesthesia. The same depth of anesthesia was maintained during the operation. We compared the propofol dosage and adverse events (eg hypotension) during anesthesia between the two groups. This study was registered with the Chinese Clinical Trial Registry, www.chictr.org.cn, number ChiCTR-TRC-16010112.

Results

There were significant differences in the total infusion dose (Vc group: 704.3 ± 188.6 mg; control group: 888.6 ± 232.7 mg; p = 0.016) and the average maintenance dose of propofol (Vc group: 5.8 ± 1.0 mg/kg/h; control group: 6.9 ± 1.6 mg/kg/h; p = 0.013). But there were no significant differences in the induction dose of propofol (control group: 90 mg, range 80-115 mg; Vc group: 100 mg, range 90-110 mg, p = 0.379) between the Vc and control groups. Furthermore, there were no significant differences in the hemodynamics and the incidence of intraoperative hypotension.

Conclusion

Vitamin C can reduce the dosage of propofol in patients undergoing total knee replacement.

Sedation outcomes for remimazolam, a new benzodiazepine

Remimazolam is a new ultrashort-acting benzodiazepine with fast onset, quick recovery, and few side effects, such as hypotension and respiratory depression. It is expected to be safe and effective for a wide range of patients undergoing intravenous sedation for dental procedures. The aim of this literature review was to evaluate clinical and sedation outcomes for remimazolam, including method of administration, level of sedation at the dose required, and clinical adverse events. An electronic literature search of databases was conducted, and eight articles were selected for inclusion in this review. Onset time from drug administration to optimal sedation level was faster for remimazolam (around 1.5-6.4 min) than for midazolam. Recovery time was significantly shorter for remimazolam than for midazolam and propofol. A study comparing various doses of remimazolam with midazolam found no significant difference in safety. Comparison of a remimazolam group with a propofol group showed that incidences of hypotension (13.0% vs 42.9%, respectively) and respiratory depression (1.1% vs 6.9%, respectively) were significantly lower for remimazolam. Remimazolam appears to be an ideal sedative.

Optimization of propofol loaded niosomal gel for transdermal delivery

Propofol is an oily liquid widely used for rapid onset of anaesthesia via intravenous route, which shows major limitations of hypersensitivity, anaphylactic reactions and pain. The aim of the present work was to bypass the above issues by formulating tailored niosomal gel to deliver propofol via non-invasive transdermal route. The niosomes were prepared by film hydration method and sonication using cholesterol and Span 80. The Box Behnken design (BBD) was applied to optimize the size (93.5 nm) and the entrapment efficacy (81.5%) of the niosomes by selecting cholesterol at 139 mg, Span 80 at 0.525% and sonication time at 5.13 min. The scanning electron microscopy image showed spherical shape niosomes with smooth surface without aggregation. The ex vivo release data showed significant improvement in the propofol release (92.2% after 10 h) using niosomes in comparison to the control propofol gel (with 30% methanol) without niosomes (25.3% after 10 h). The in vivo pharmacokinetic parameters in the rat model confirmed the improvement in the relative bioavailability with optimized niosomal gel (relative bioavailability = 12.12) in comparison to the control propofol gel. In conclusion, the niosomal gel offered a potential alternative non-invasive route to deliver propofol for procedural sedation especially in pediatric population.

Moderate-to-Deep Sedation Using Target-Controlled Infusions of Propofol and Remifentanil: Adverse Events and Risk Factors: A Retrospective Cohort Study of 2937 Procedures

BACKGROUND

In the University Medical Center Groningen in Groningen, the Netherlands, moderate-to-deep sedation is provided by nursing staff trained and supervised by the anesthesia department using protocol-based target-controlled infusions (TCIs) of propofol and remifentanil. The aim of this retrospective cohort study was to investigate the incidence of events with potential adverse health consequences within this service model and the risk factors for the occurrence of these events.

METHODS

We retrospectively interrogated a database containing the computerized anesthetic records of 2937 procedures where moderate-to-deep sedation was provided using TCI administration of propofol and remifentanil between May 2014 and October 2017. The primary outcome measures were the incidence of sedation-related events with potential adverse health consequences and risk factors for the occurrence of such events. The events under investigation were unplanned intensive care unit (ICU) admission, need for cardiopulmonary resuscitation (CPR), death on the day of the procedure due to sedation-related events, cardiovascular events (arrhythmias, hypertension, and hypotension), pulmonary events (aspiration, desaturation, unplanned tracheal intubation), anaphylactic or allergic reactions, and the termination of the procedure due to sedation-related events. Cardiovascular and pulmonary events were classified as severe, significant, or moderate. Events were identified by using computer algorithms to search the computerized records from all included procedures.

RESULTS

Data from 2937 procedures were analyzed. No patients suffered catastrophic events (death, need for CPR, or unplanned ICU admission). Thirty-two severe sedation-related events occurred in 32 procedures. Severe desaturation (0.6%; 95% confidence interval [CI], 0.4-0.9) and severe hypertension (0.2%; 95% CI, 0.04-0.37) were the most common severe events. Significant hypotension (8.8%; 95% CI, 7.73-9.77) and significant desaturation (1.6%; 95% CI, 1.12-2.02) were found to be the most common events with potential adverse health consequences. No patient suffered lasting health consequences. Average mean and maximum targeted effect-site concentrations (Cet) for propofol were 2.6 ± 0.83 and 3.3 ± 1.09 µg·mL, respectively, and for remifentanil 0.84 ± 0.18 and 0.99 ± 0.22 ng·mL, respectively. Maximum Cets of propofol were lower among patients with higher body mass index (BMI) and were higher among patients of younger age. Higher BMI was a risk factor for desaturation. Increased age and lower BMI were risk factors for hypotension. Longer procedure time was a risk factor for both desaturation and hypotension.

CONCLUSIONS

Moderate-to-deep sedation by propofol and remifentanil TCI has a low incidence of catastrophic and severe events.

Influence of pre-anesthesia dynamic frontal-parietal communication on individual susceptibility to propofol

OBJECTIVE

We investigated whether pre-anesthesia dynamic frontal-parietal functional connectivity was correlated with the observed interindividual differences in propofol susceptibility.

METHODS

Three resting-state EEG datasets were used in the study (N = 29, N = 21 and N = 20). We estimated the pre-anesthesia strength and fluctuations of frontal-parietal functional connectivity by using sliding-window analysis. Propofol served as the sole anesthetic drug, and it was administered by using a target-controlled infusion system. Individual susceptibility to propofol was assessed by the induction time, from infusion onset until a bispectral index value of 60 was reached, for subjects in dataset-1 and dataset-2, and susceptibility was assessed by behavioral data for subjects in the external dataset.

RESULTS

We observed in the three datasets that subjects with high susceptibility to propofol had lower pre-anesthesia strength and lower fluctuation of frontal-parietal functional connectivity than the low-susceptibility group at alpha band. Moreover, the induction time was significantly correlated with the estimated pre-anesthesia frontal-parietal functional connectivity measures. We also validated the robustness of these findings by using different window lengths in sliding-window analysis.

CONCLUSIONS

Subjects with weaker pre-anesthesia dynamic frontal-parietal communication are more likely to be anesthetized.

SIGNIFICANCE

These observations suggest that the titration procedure for propofol should consider the pre-anesthesia brain functional state.

Spectral and Entropic Features Are Altered by Age in the Electroencephalogram in Patients under Sevoflurane Anesthesia

BACKGROUND

Preexisting factors such as age and cognitive performance can influence the electroencephalogram (EEG) during general anesthesia. Specifically, spectral EEG power is lower in elderly, compared to younger, subjects. Here, the authors investigate age-related changes in EEG architecture in patients undergoing general anesthesia through a detailed examination of spectral and entropic measures.

METHODS

The authors retrospectively studied 180 frontal EEG recordings from patients undergoing general anesthesia, induced with propofol/fentanyl and maintained by sevoflurane at the Waikato Hospital in Hamilton, New Zealand. The authors calculated power spectral density and normalized power spectral density, the entropic measures approximate and permutation entropy, as well as the beta ratio and spectral entropy as exemplary parameters used in current monitoring systems from segments of EEG obtained before the onset of surgery (i.e., with no noxious stimulation).

RESULTS

The oldest quartile of patients had significantly lower 1/f characteristics (P < 0.001; area under the receiver operating characteristics curve, 0.84 [0.76 0.92]), indicative of a more uniform distribution of spectral power. Analysis of the normalized power spectral density revealed no significant impact of age on relative alpha (P = 0.693; area under the receiver operating characteristics curve, 0.52 [0.41 0.63]) and a significant but weak effect on relative beta power (P = 0.041; area under the receiver operating characteristics curve, 0.62 [0.52 0.73]). Using entropic parameters, the authors found a significant age-related change toward a more irregular and unpredictable EEG (permutation entropy: P < 0.001, area under the receiver operating characteristics curve, 0.81 [0.71 0.90]; approximate entropy: P < 0.001; area under the receiver operating characteristics curve, 0.76 [0.66 0.85]). With approximate entropy, the authors could also detect an age-induced change in alpha-band activity (P = 0.002; area under the receiver operating characteristics curve, 0.69 [0.60 78]).

CONCLUSIONS

Like the sleep literature, spectral and entropic EEG features under general anesthesia change with age revealing a shift toward a faster, more irregular, oscillatory composition of the EEG in older patients. Age-related changes in neurophysiological activity may underlie these findings however the contribution of age-related changes in filtering properties or the signal to noise ratio must also be considered. Regardless, most current EEG technology used to guide anesthetic management focus on spectral features, and improvements to these devices might involve integration of entropic features of the raw EEG.

Utilisation of medications among elderly patients in intensive care units: a cross-sectional study using a nationwide claims database

OBJECTIVES

Clinical practice guidelines for the management of pain and sedation in critically ill patients have been developed and applied; however, there is limited data on medication use among elderly patients. This study identifies current practice patterns for analgo-sedative use in mechanically ventilated elderly patients in Korea using a national claims database.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

Ventilated elderly patients aged 65 years or older in intensive care units (ICUs) from an aged patients' national claims database in Korea PRIMARY OUTCOME MEASURES: Use of sedatives including benzodiazepines, opioids and non-opioid analgesics, neuromuscular blocking agents (NMBAs) and antipsychotic drugs were analysed by the duration of mechanical ventilation (MV), age and time.

RESULTS

From 2012 to 2016, 22 677 elderly patients underwent MV in 267 general or tertiary ICUs. Mean age was 77.2 (±6.9) years and the median duration of MV was 4.1 days; 77.2% of patients received sedatives, 65.0% analgesics, 29.1% NMBAs and 19.6% antipsychotics. Midazolam (62.0%) was the most commonly prescribed medication. The proportions of sedatives, analgesics and NMBAs increased, whereas the percentages of person-days decreased with longer MV duration (p<0.01). With advanced age, the prevalence and duration of sedative, analgesic and NMBA use decreased (adjusted OR (95% CI) 0.98 (0.97 to 0.98) in all three classes) while antipsychotic did not (adjusted OR 1.00 (1.00-1.01)). Annually, benzodiazepines showed reduced administration (76.2% in 2012 and 71.4% in 2016, p<0.01), while daily opioid dose increased (21.6 in 2012 vs 30.0 mg in 2016, p<0.01).

CONCLUSIONS

The prevalence of sedative, analgesic and NMBAs use and daily opioid doses were lower, whereas antipsychotic use was higher compared with those in previous studies in adult patients. The findings warrant further studies investigating appropriateness and safety of medication use that consider clinical severity scores with a focus on elderly patients in ICUs.

Effect of Auricular Acupuncture on Propofol Induction Dose: Could Vagus Nerve and Parasympathetic Stimulation Replace Intravenous Co-Induction Agents?

Objective: Auricular acupuncture, through a combination of several points, can produce sedative and analgesic effects. The aim of this study was to compare the induction dose of propofol required to obtain a loss of response to verbal commands, with and without a preoperative combination of auricular points. Materials and Methods: This study involved American Society of Anesthesiologists physical status I and II patients, ages 18- 65, of either sex, having elective ambulatory surgery (digestive or gynecologic) under general anesthesia. The subjects were allocated to 2 groups: (1) patients treated by auricular acupuncture (group AA), compared with (2) patients not treated by auricular acupuncture (group NA). Propofol injection was initiated in each group, 10 mg, every 5 seconds, in order for the anesthetist to determine the minimum dose until there was a loss of response to verbal commands (the clinical hypnotic endpoint). At this point, the main outcome-the dose of propofol given-was noted. Results: There were 32 patients in this study (16 in each group). Age, height, weight, and body mass index were similar in the groups (P ≥ 0.05). The required induction propofol dose was 17.7% lower in group AA than in group NA-a statistically significant difference (P ≤ 0.05). The mean induction dose indexed to weight was 2.18 mg/kg (range: 1.53-3.13 mg/kg) in group NA and 1.79 mg/kg (range: 1.12-2.11 mg/kg) in group AA. There were no complications. Conclusions: Auricular acupuncture is a method for stimulating the vagus nerve and parasympathetic nervous system. Preoperative auricular acupuncture enabled reductions of induction doses of propofol for general anesthesia without any clinically important side-effects.

Previously published drug interaction models predict loss of response for transoesophageal echocardiography sedation well but not response to oesophageal instrumentation

Response surface models (RSMs) were used to predict effects of multiple drugs interactions. Our study was aimed to validate accuracy of the previous published volunteer models during transoesophageal echocardiography (TEE). This is a cross-sectional study with 20 patients scheduled for transesophageal echocardiography in Taipei Veterans General Hospital, Taiwan. Effect-site concentration pairs of alfentanil and propofol were recorded and converted to equivalent remifentanil and propofol effect-site concentrations. Observer’s Assessment of Alertness/Sedation (OAA/S) scores were assessed every 2 minutes. Using these data, previous published models of loss of response (LOR), intolerable ventilatory depression (IVD), and loss of response to esophageal instrumentation (LREI) were then estimated. Accuracy of prediction is assessed by calculating the difference between the true response and the model-predicted probability. Clinical events such as interruption of TEE were recorded. The average procedure time was 11 minutes. Accuracy for prediction of LOR and LREI is 63.6% and 38.5%, respectively. There were four patients experienced desaturation for less than 1 minute, which were not predicted by IVD model, and one interruption of TEE due to involuntary movement. The previous published drug-interaction RSMs predict LOR well but not LREI for TEE sedation. Further studies using response surface methodology are needed to improve quality for TEE sedation and clinical implementation.

Randomized Double-blind Comparison of Ketamine-Propofol, Fentanyl-Propofol and Propofol-Saline on Haemodynamics and Laryngeal Mask Airway Insertion Conditions

The aim of this prospective, double-blind, randomized, placebo-controlled clinical trial was to investigate whether the administration of ketamine before induction with propofol improves its associated haemodynamic profile and laryngeal mask airway (LMA) insertion conditions. Ninety adult patients were randomly allocated to receive either ketamine 0.5 mg.kg-1 (n=30), fentanyl 1 μg.kg-1 (n=30) or normal saline (n=30), before induction of anaesthesia with propofol 2.5 mg.kg-1. Insertion of the LMA was performed 60s after injection of propofol. Arterial blood pressure and heart rate were measured before induction (baseline), immediately after induction, immediately before LMA insertion, immediately after LMA insertion and every minute for three minutes after LMA insertion. Following LMA insertion, the following six subjective endpoints were graded by a blinded anaesthestist using ordinal scales graded 1 to 3: mouth opening, gagging, swallowing, movement, laryngospasm and ease of insertion. Systolic blood pressure was significantly higher following ketamine than either fentanyl (P=0.010) or saline (P=0.0001). The median (interquartile range) summed score describing the overall insertion conditions were similar in the ketamine [median 7.0, interquartile range (6.0–8.0)] and fentanyl groups [median 7.0, interquartile range (6.0–8.0)]. Both appeared significantly better than the saline group [median 8.0, interquartile range (6.75–9.25); P=0.024]. The incidence of prolonged apnoea (>120s) was higher in the fentanyl group [23.1% (7/30)] compared with the ketamine [6.3% (2/30)] and saline groups [3.3% (1/30)]. We conclude that the addition of ketamine 0.5 mg.kg–1 improves haemo-dynamics when compared to fentanyl 1 μg.kg–1, with less prolonged apnoea, and is associated with better LMA insertion conditions than placebo (saline).

Correlation and Linear Regression between Blood Pressure Decreases after a Test Dose Injection of Propofol and that following Anaesthesia Induction

Propofol reduces systemic vascular resistance and suppresses cardiac function when injected rapidly. In this study we investigated whether blood pressure decrease after a minimal dose (test-dose) injection of propofol correlates with that after an induction-dose injection.

Patients were randomly divided into two groups; anaesthesia was induced in group A (n=60) using 1.5 mg/kg propofol and in group B (n=61) using 2.0 mg/kg. Blood pressure reduction after a minimal dose injection (0.4 mg/kg) was examined non-invasively prior to anaesthetic induction. Bispectral Index monitoring was measured and sedation level scored to evaluate anaesthetic depth.

After the minimal dose injection, 18 of 121 patients showed behaviour suggesting minor disinhibition, five patients were sedated and seven were drowsy. Oxygen saturation was not significantly changed after test-dose injection. Reduction in systolic blood pressure (mean±SD) was 17±11 mmHg after the minimal dose injection, 42±20 mmHg after a 1.5 mg/kg induction dose injection, and 42±22 mmHg after a 2.0 mg/kg induction-dose injection. In both groups, blood pressure after induction was significantly lower than the control value (P<0.05). In both groups, a positive correlation was observed between blood pressure reduction after the minimal dose injection and that after the induction-dose injection [P<0.01, R value for systolic blood pressure correlation in group A 0.712 (P<0.01) and in group B 0.758 (P<0.01)].

We concluded there was a positive correlation between blood pressure reduction after a minimal (test-dose) injection and that after an induction-dose injection.

Prediction of hemodynamic fluctuations after induction of general anesthesia using propofol in non-cardiac surgery: a retrospective cohort study

Background

Although propofol is a common anesthetic agent for the induction of general anesthesia, hemodynamic fluctuations are occasionally prominent during induction/intubation. The aims of this study were to determine the influential factors on enhanced hemodynamic fluctuation and to establish a prediction formula to quickly determine the dose of propofol to protect against hemodynamic fluctuations.

Methods

This retrospective cohort study patients (n = 2097) were 18 years or older. They underwent general anesthesia induction using propofol and orotracheal intubation for non-cardiac surgery at Kyushu University Hospital during April 2015 to March 2016. Preoperative patient clinical information was collected from anesthesia preoperative evaluation records. Intraoperative data were obtained from computerized anesthesia records. If patients’ post-induction mean arterial blood pressure (MAP) decreased or increased 30% or more from their pre-induction MAP, they were determined to have enhanced hemodynamic fluctuations. Unconditional logistic regression was used to assess the adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Structural equation modeling (SEM) was conducted to simultaneously examine the direct and indirect effect (path coefficient = r) of potential variables.

Results

In the SEM analysis, age was significantly associated with enhanced hemodynamic fluctuations (adjusted odds ratio = 1.008, 95% CI = 1.001–1.015, P = 0.03). Age (path coefficient (r) = − 0.0113, 95% CI = − 0.0126–0.010, P < 0.001), American Society of Anesthesiologists physical status (ASA-PS) (r = − 0.0788, 95% CI = − 0.1431–0.0145, P = 0.02), sex (r = 0.057, 95% CI = 0.0149–0.9906, P = 0.01), and fentanyl dose (r = 0.1087, 95% CI = 0.0707–0.1467, P < 0.001) influenced the dose of propofol in induction. The prediction formula of “Propofol dose (mg) = [2.374 – 0.0113 × age (year) – 0.0788 (if ASA-PS 3 or 4) + 0.057 (if female) + 0.1087 × fentanyl dose (μg/kg)] × body weight (kg)” was derived.

Conclusions

Age was associated with hemodynamic fluctuations in induction. Although the prediction formula is considered to be acceptable, future studies validating whether it can decrease patients’ risk of enhanced hemodynamic fluctuations in clinical situations are necessary.

Etomidate versus propofol sedation for electrical external cardioversion: a meta-analysis

OBJECTIVE

To compare the efficacy and safety of etomidate vs propofol sedation for electrical cardioversion.

METHODS

The authors searched the MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials, Google Scholar, Koreamed, and KMBASE databases to identify all randomized controlled trials that compared etomidate and propofol sedation for cardioversion in adult patients. Induction and recovery time, success rate, number of shocks, and cumulative energy were evaluated. Adverse effects, including respiratory and cardiovascular complications, myoclonus, and nausea and vomiting, were also assessed.

RESULTS

A total of nine studies, involving a total of 430 patients, were included. Induction and recovery time, success rate, number of shocks, and cumulative energy were similar. The incidences of hypotension and respiratory depression were significantly higher in the propofol group than in the etomidate group (risk ratio [RR] = 0.11, 95% confidence interval (CI) = 0.02-0.74, I² = 0%; RR = 0.50, 95% CI = 0.32-0.77, I² = 47%, respectively). The incidences of myoclonus and nausea or vomiting were significantly higher in the etomidate group than in the propofol group (RR = 8.89, 95% CI  =  4.59-17.23, I² = 9%; RR = 5.13, 95% CI = 1.72-15.31, I² = 31%, respectively).

CONCLUSIONS

Issues affecting efficacy, including induction and recovery time, success rate, number of shocks, and cumulative energy, were comparable between etomidate and propofol sedation. Regarding safety issues, propofol sedation resulted in hypotension and respiratory depression more frequently; however, initiation of positive pressure ventilation was comparable. Etomidate sedation caused myoclonus and nausea or vomiting more frequently.

Metabolic Profiles of Propofol and Fospropofol: Clinical and Forensic Interpretative Aspects

Propofol is an intravenous short-acting anesthetic widely used to induce and maintain general anesthesia and to provide procedural sedation. The potential for propofol dependency and abuse has been recognized, and several cases of accidental overdose and suicide have emerged, mostly among the health professionals. Different studies have demonstrated an unpredictable interindividual variability of propofol pharmacokinetics and pharmacodynamics with forensic and clinical adverse relevant outcomes (e.g., pronounced respiratory and cardiac depression), namely, due to polymorphisms in the UDP-glucuronosyltransferase and cytochrome P450 isoforms and drugs administered concurrently. In this work the pharmacokinetics of propofol and fospropofol with particular focus on metabolic pathways is fully reviewed. It is concluded that knowing the metabolism of propofol may lead to the development of new clues to help further toxicological and clinical interpretations and to reduce serious adverse reactions such as respiratory failure, metabolic acidosis, rhabdomyolysis, cardiac bradyarrhythmias, hypotension and myocardial failure, anaphylaxis, hypertriglyceridemia, renal failure, hepatomegaly, hepatic steatosis, acute pancreatitis, abuse, and death. Particularly, further studies aiming to characterize polymorphic enzymes involved in the metabolic pathway, the development of additional routine forensic toxicological analysis, and the relatively new field of ‘‘omics” technology, namely, metabolomics, can offer more in explaining the unpredictable interindividual variability.

Anesthesia for Bedside Procedures

Within the past 10 years, numerous short-acting anesthetic drugs have been introduced for use in the operating room. This review article will discuss the role of these agents in critically ill patients undergoing bedside procedures.

After a brief historical update, the first part of the review will focus on issues related to the pathophysiology and pharmacology of critically ill patients in general, and of specific organ dysfunction in particular. In-appropriate dosing and improper selection of agents will be highlighted. The second part of the article will discuss specific classes of drugs, with reference to their advantages and disadvantages in the ICU population.

The article will conclude by emphasizing the potency, safety, and efficacy of these drugs in significantly reducing the pain and suffering experienced by patients with critical illness.

The administration of high-dose propofol sedation with manual and target-controlled infusion in children undergoing radiation therapy: a 7-year clinical investigation

Background

Radiation therapy requires the patient to remain immobile for a long time, which is challenging in children. This study therefore aimed to determine the adequate target concentration and dosage of propofol in target-controlled infusion (TCI) and manual infusion (MI) in children requiring sedation for proton radiation therapy. Our hypothesis is that the adequate dose of propofol sedation required for proton radiation therapy in pediatric patients was larger than that seen in previous studies.

Methods

We retrospectively analyzed the medical records of Korean children who received proton therapy under propofol sedation. The average target concentration at induction and during maintenance with TCI and the dose with MI were analyzed as primary outcomes.

Results

A total of 1296 procedures in 54 children were analyzed (TCI group, 26; MI group, 28). The median bolus dose of propofol in the MI group was 2.6 (2.2–3.0) mg/kg, while the pump speed was 17.0 (13.6–25.8) mg/kg/h. The median target concentration of propofol in the TCI group was 5.3 (4.4–5.7) mcg/mL at induction and 4.2 (3.1–5.1) mcg/mL during maintenance. There were no cases of life-threatening complications in either group over 7 years. There were six cases of transient desaturation, which were managed by using the jaw thrust maneuver.

Conclusions

Compared with those in previous studies, the target concentration of propofol with TCI and the propofol dose with MI required for adequate sedation in children undergoing proton radiation therapy were larger in the present study. Despite concerns regarding overdosage, the complications were managed well. However, safe and adequate sedation for proton radiation therapy remains a challenge. The development of monitoring tools to evaluate the depth of sedation is necessary to adjust the propofol dose and sedation level.

Comparison of Laryngeal Mask Airway Supreme(TM) Versus Unique(TM) in Edentulous Geriatric Patients

OBJECTIVE

It is more difficult to perform bag-mask ventilation in edentulous patients than in patients with intact dentition. The laryngeal mask airway (LMA) provides a better alternative to the standard face mask if the facial contours of the patient are not suited for the standard face mask. We aimed to compare these two different LMAs in edentulous geriatric patients.

METHODS

Edentulous patients aged ≥65 years of American Society of Anesthesiologists physical status I-III were included in the study. They were randomly assigned to Supreme group (n=30) and Unique group (n=30). Success of first insertion attempt, ease and time of insertion and oropharyngeal leak pressure were recorded.

RESULTS

The success rate of the first insertion attempt was higher in the Supreme group than in the Unique group (86.6 and 73.3%, respectively; p=0.04). Time of insertion was similar (10.04 s and 11.87 s, respectively) and insertion was easy in 90% and 100% of patients, respectively. Oropharyngeal leak pressures were measured as 20.56-cm H2O and 17.10-cm H2O for LMA Supreme™ and LMA Unique™, respectively.

CONCLUSION

The efficacy and safety in both groups were comparable in edentulous geriatric patients during short surgical procedures. Even the success rate of insertion with both was lower than that mentioned in the literature; the success of insertion at the first attempt was superior with the LMA Supreme™ in our edentulous study group.

Propofol Use in the Elderly Population: Prevalence of Overdose and Association With 30-Day Mortality

PURPOSE

Geriatric patients are more sensitive to the anesthetic effects of propofol and its adverse effects, such as hypotension, than is the general population; thus, a reduced dose (1-1.5 mg/kg) is recommended for the induction of anesthesia. The extent to which clinicians follow established dosing guidelines has not been well described. Therefore, we investigated the prevalence of propofol overdose in the elderly population to determine whether propofol overdose occurs and is associated with increased hypotension and 30-day mortality.

METHODS

In this retrospective study in patients who received propofol for the induction of general anesthesia, data on demographic characteristics, preoperative medications, intraoperative management, and 30-day mortality were collected. The dose of propofol used for the induction of anesthesia and the median blood pressure in the pre- and immediate postinduction periods were determined. Hypotension was defined as either: (1) a decrease in mean arterial pressure (MAP) of >40% concurrent with a MAP of <70 mm Hg; or (2) a MAP of <60 mm Hg.

FINDINGS

A total of 17,540 patients were included in the analysis; 4033 (23.0%) were aged >65 years. The median (interquartile range) propofol dose in the group aged >65 years was 1.8 (1.4-2.2) mg/kg, above the recommended dose, in comparison to 2.2 (1.9-2.5) mg/kg in younger patients. On multivariate analysis, increased propofol dose was associated with increased postinduction hypotension, especially in patients over 70 years of age, but not 30-day mortality.

IMPLICATIONS

Older patients received greater-than-recommended doses of propofol for induction, which may have led to significant dose-dependent hypotension. Despite this finding, the dose of propofol for induction was not independently associated with a greater 30-day mortality rate. More education regarding geriatric concerns is needed for encouraging anesthesiologists to tailor the plan for anesthesia in geriatric patients. However, overall postsurgical mortality is a function of preoperative risk and type surgical procedure.

Anesthetic Considerations for Common Procedures in Geriatric Patients: Hip Fracture, Emergency General Surgery, and Transcatheter Aortic Valve Replacement

The elderly population is growing. Geriatric patients undergo a large proportion of surgical procedures and have increased complications, morbidity, and mortality, which may be associated with increased intensive care unit time, length of stay, hospital readmission, and cost. Identification of optimal anesthetic care for these patients, leading to decreased complications and contributing to best possible outcomes, will have great value. This article reviews the anesthetic considerations for intraoperative care of geriatric patients and focus on 3 procedures (hip fractures, emergency abdominal surgery, and transcatheter aortic valve replacement). An approach to evaluation and management of the elderly surgical patient is described.

Is propofol an optimal agent for procedural sedation and rapid sequence intubation in the emergency department?

Objective:

We conducted a qualitative systematic review to evaluate the efficacy and safety of propofol for direct current cardioversion (DCC), rapid sequence intubation (RSI) and procedural sedation in adult emergency department (ED) patients.

Data source:

MEDLINE (1966 to September 2000), PubMed (to September 2000), EMBASE (1988 to September 2000), Database of Systematic Reviews (to September 2000), Best Evidence (1991 to September 2000) and Current Contents (1996 to September 2000) databases.

Study selection:

English-language, randomized, comparative evaluations of propofol for procedures routinely conducted in adults (&gt;18 years) were included. Direct current cardioversion, RSI and procedural sedation were considered.

Data extraction:

Efficacy and safety endpoints were evaluated for all trials. For DCC and procedural sedation trials, efficacy measures included induction and recovery times, as well as the association for successful procedure. For the RSI trials, optimal intubating conditions were evaluated as the primary efficacy endpoint. Safety measures included hemodynamic changes, apnea rates and adverse effects.

Data synthesis:

In the setting of DCC, efficacy and safety outcomes were similar for propofol, thiopental, etomidate and methohexital. All of these agents provided markedly shorter induction and recovery times than midazolam. Patients who were pre-medicated with fentanyl exhibited prolonged recovery times and greater decreases in blood pressure. When used for RSI, propofol administration was associated with satisfactory intubating conditions that were comparable to those seen with thiopental and etomidate. Blood pressure reductions were seen in both DCC and RSI studies. Apneic episodes (&gt;30 seconds) occurred in 23% of propofol recipients, 28% of thiopental recipients and 7% of etomidate and midazolam recipients. Apart from the DCC studies described, no procedural sedation studies met our predefined review eligibility criteria.

Conclusion:

The body of literature evaluating propofol for DCC and RSI in the ED is limited. There is evidence to support the use of propofol for DCC and RSI, but this evidence comes from stable patients in non-ED settings. Further ED-based randomized comparative trials should be conducted before propofol is adopted for widespread use in the ED.

Special anesthetic consideration for the patient with a fragility fracture

In this article, an overview is presented of perioperative management of the patient with a fragility fracture, including preoperative risk stratification and optimization, anesthesia risks, anesthesia options, and postoperative pain management. Issues of preoperative evaluation that are of concern for the anesthesiologist because of their direct effect on intraoperative care are discussed. A team interdisciplinary approach and good communication between specialties involved in care of elderly surgical patients is important for optimal patient outcomes and to avoid perioperative complications. Cooperation between anesthesiology and medicine is indispensable in reaching a reasonable consensus regarding preoperative evaluation and should occur on a case-by-case basis.

Effects of Ketamine-Propofol Mixture on Intraocular Pressure and Haemodynamics in Elderly Patients: A Randomised Double-Blind Trial

OBJECTIVE

The aim of this study was to compare the effects of a ketamine-propofol mixture (ketofol) and propofol on intraocular pressure (IOP) and haemodynamics in elderly patients during anaesthetic management at each repeated measurement times.

METHODS

Forty elderly ASA I and II patients were divided into two random groups and received either propofol (1.5 mg kg(-1); group P, n=20) or ketofol (1:1 single syringe mixture of 5 mg mL(-1) ketamine and 5 mg mL(-1) propofol; group KP, n=20). A proseal laryngeal mask airway (PLMA) was inserted 60 seconds after induction of anaesthesia. IOP, systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) values were recorded at preinduction (t0), immediately following induction (t1), and at 1 (t2), 3 (t3), and 5 (t4) minutes after induction. Haemodynamic complications and the need for ephedrine were also recorded.

RESULTS

Patient characteristics at the beginning of the procedure were similar between the groups. SBP and HR were significantly increased in group KP compared to group P at t1 and t4 (p=0.044). Induction of both anaesthetic agents significantly decreased the IOP values from the t0 (p=0.026). A significant decrease in IOP was found at t1 and t4 in group P compared to group KP (p=0.018). The total dose of ephedrine was statistically different in group P (p=0.034).

CONCLUSION

Ketofol can be an alternative agent to provide haemodynamic stability with a moderate decrease in IOP during anaesthesia induction in elderly patients.

Anesthetic drug development: Novel drugs and new approaches

The ideal sedative–hypnotic drug would be a rapidly titratable intravenous agent with a high therapeutic index and minimal side effects. The current efforts to develop such agents are primarily focused on modifying the structures of existing drugs to improve their pharmacodynamic and pharmacokinetic properties. Drugs currently under development using this rational design approach include analogues of midazolam, propofol, and etomidate, such as remimazolam, PF0713, and cyclopropyl methoxycarbonyl-etomidate (MOC-etomidate), respectively. An alternative approach involves the rapid screening of large libraries of molecules for activity in structural or phenotypic assays that approximate anesthetic and target receptor interactions. Such high-throughput screening offers the potential for identifying completely novel classes of drugs. Anesthetic drug development is experiencing a resurgence of interest because there are new demands on our clinical practice that can be met, at least in part, with better agents. The goal of this review is to provide the reader with a glimpse of the novel anesthetic drugs and new developmental approaches that lie on the horizon.

Comparison of effects of propofol and ketamine-propofol mixture (ketofol) on laryngeal mask airway insertion conditions and hemodynamics in elderly patients: a randomized, prospective, double-blind trial

PURPOSE

The objective of this study was to compare the effects of ketamine-propofol mixture (ketofol) and propofol on ProSeal laryngeal mask airway (PLMA) insertion conditions and hemodynamics in elderly patients.

METHODS

Eighty elderly patients, American Society of Anesthesiologists (ASA) physical status I and II, were randomly divided into two groups to receive either propofol 0.15 ml/kg (n = 40), or ketofol (using a 1:1 single-syringe mixture of 5 mg/ml ketamine and 5 mg/ml propofol) (n = 40) before induction of anesthesia. Sixty seconds after induction, the PLMA was inserted. Heart rate and arterial blood pressure (systolic [S] BP) were recorded prior to the induction of anesthesia, immediately following induction, immediately after PLMA insertion, and 5 and 10 min after PLMA insertion. PLMA insertion conditions were scored according to mouth opening, swallowing, coughing, head and body motion, laryngospasm, and ease of PLMA insertion by the same experienced anesthesiologist, who did not know which agents were used.

RESULTS

There were no differences in PLMA insertion conditions between the groups. The number of patients in need of ephedrine (P = 0.043) and the total dose of ephedrine (P = 0.022) were significantly lower, and apnea duration (P < 0.001) was significantly higher in the ketofol group compared with the propofol group. SBP was significantly higher in the ketofol group than in the propofol group immediately after PLMA insertion and 5 min after PLMA insertion.

CONCLUSIONS

The same PLMA insertion conditions were found with ketofol and propofol. The number of patients in need of ephedrine and the total ephedrine dose were lower and apnea duration was increased in the ketofol group.

Prospective observational evaluation of incidences and implications of drug-drug interactions induced adverse drug reactions in critically ill patients

The primary aim of this study is to identify and analyze the importance of adverse drug reaction due to drug-drug interaction as a contributing factor towards drug safety. Patients more than 18 years of age admitted in multidisciplinary intensive care unit of a tertiary care hospital were included in this study. Patients who stayed less than 48 h and patients in whom all treatment modalities have been withdrawn and were on comfort measures only (no drugs were prescribed), were excluded. All the drugs that were given during intensive care unit stay were checked for presence of potential interactions which led to adverse drug reaction. Drug-drug interactions that were detected clinically or through investigations were recorded and also any therapeutic actions taken for drug-drug interactions were noted. From June 2006 to April 2007, 400 patients-prescriptions were analyzed. Adverse drug reactions due to drug-drug interactions were identified in 64% patients. Among those patients 38.67% had a single drug-drug interaction. Potential drug-drug interactions were 602. Clinically significant drug-drug interactions among the potential were 208 (34.55%). Clinically relevant drug-drug interactions were 103 (49.52% of 208 episodes). The adverse drug reactions due to drug-drug interactions in our sample were managed either by substituting another drug (50.48% of 103 episodes) or by adjusting the dose (1% of 103 episodes) or by omitting the drug (48.54% of 103 episodes). Among the 208 observed drug-drug interactions induced adverse drug reactions 21.63% was severe drug-drug interactions induced adverse drug reactions, 23.08% was moderate drug-drug interactions induced adverse drug reactions and 55.29% was minor drug-drug interactions induced adverse drug reactions. The interactions which were life threatening and/ or require medical intervention to minimize or prevent serious adverse effects were considered as severe drug-drug interactions and those interaction which resulted in an exacerbation of the patient's condition and/ or require an alteration in therapy were considered as moderate drug-drug interactions. The interactions which were limited clinical effects and manifestations may include an increase in the frequency or severity of side effects but generally would not require a major alteration in therapy were classified as minor drug-drug interactions. The correlation coefficient was 0.86 between the number of drugs given to the patient & number of average potential adverse drug reactions found among the patients. Increase in number of prescribed drug significantly (one way) increases number of potential adverse drug reaction due to drug-drug interaction (p<0.0001). Critically ill patients are more susceptible to drug-drug interactions due to the administration of multiple drugs and complex drug combinations. Several drug-drug interactions were clinically irrelevant.

Pretreatment with small-dose ketamine reduces predicted effect-site concentration of propofol required for loss of consciousness and Laryngeal Mask Airway insertion in women

STUDY OBJECTIVE

To investigate the effect of small-dose ketamine on the predicted effect-site concentration of propofol required for loss of consciousness (LOC) and Laryngeal Mask Airway (LMA) insertion.

DESIGN

Randomized, double-blinded study.

SETTINGS

Operating room.

PATIENTS

50 ASA physical status 1 and 2 women scheduled for elective breast or gynecological surgery.

INTERVENTIONS

Patients were randomly allocated to a ketamine group or a control group. Thirty seconds before propofol injection, ketamine group patients received ketamine 0.2 mg/kg, while control group patients received saline. Propofol was given in a target-controlled infusion and target blood concentration was gradually increased until LOC. The effect-site concentrations for attempting LMA insertion was predetermined by modifying Dixon's up and down method. LMA insertion was attempted without muscular blocking agents.

MEASUREMENTS

Pain scores on propofol injection, effect-site concentrations at LOC, hemodynamic variables, and patient movement or side effects on LMA insertion were recorded.

MAIN RESULTS

The effect-site concentration of propofol required for LOC was 2.14 μg/mL for the control group and 1.66 for the ketamine group (P = 0.0082). The predicted effect-site concentration of propofol alone at which 50% of patients did not move with LMA insertion (EC(50)LMI) was 3.59 μg/mL (95% CI: 3.18 ∼ 4.19 μg/mL). Pretreatment with ketamine 0.2 mg/kg decreased EC(50)LMI from 3.59 (3.18 ∼ 4.19) to 2.39 (1.22 ∼ 2.99).

CONCLUSIONS

Pretreatment with ketamine 0.2 mg/kg reduced the propofol concentration required for both LOC (22%) and LMA insertion (33%) in women.

Onset time and haemodynamic response after thiopental vs. propofol in the elderly: a randomized trial

BACKGROUND

The induction dose of hypnotic agents should be reduced in the elderly, but it is not well studied whether thiopental or propofol should be preferred in this group of patients. The aim of this study was to compare onset time, hypnosis level and the haemodynamic response after thiopental vs. propofol for induction of anaesthesia. Our primary hypothesis was that in the elderly, thiopental had a shorter onset time than propofol, defined as time to bispectral index (BIS) <50.

METHODS

In this randomized and double-blinded study, we included 78 patients. Patients were eligible, if they were scheduled for elective surgery with general anaesthesia and aged 60 or older. Patients received alfentanil 10 μg/kg and either thiopental 2.5 mg/kg or propofol 1.0 mg/kg, and depth of anaesthesia was determined with BIS the following 120 s along with clinical assessment of anaesthetic depth. The primary endpoint was the time from start of injection of the hypnotic to a BIS value below 50.

RESULTS

Time to BIS <50 was significantly shorter in patients receiving thiopental, where onset time was 52 s (median value) compared with 65 s in the propofol group (P=0.01). Mean arterial pressure decreased 25.6 mmHg in the propofol group and 15.6 mmHg in the thiopental group (P=0.003) within 120 s. Heart rate decreased 9.1 b.p.m. within 120 s in the patients receiving propofol compared with a decrease of 5.1 b.p.m. in patients receiving thiopental (P=0.04).

CONCLUSION

Thiopental was found to have a faster onset than propofol in elderly surgical patients.

Optimal sedation for gastrointestinal endoscopy: review and recommendations

Sedation practices for endoscopy vary widely. The present review focuses on the commonly used regimens in endoscopic sedation and the associated risks and benefits together with the appropriate safety measures and monitoring practices. In addition, alternatives and additions to intravenous sedation are discussed. Personnel requirements for endoscopic sedation are reviewed; there is evidence presented to indicate that non-anesthetists can administer sedative drugs, including propofol, safely and efficaciously in selected cases. The development of endoscopic sedation as a multi-disciplinary field is highlighted with the formation of the Australian Tripartite Endoscopy Sedation Committee. This comprises representatives of the Australian and New Zealand College of Anaesthetists, the Gastroenterological Society of Australia and the Royal Australasian College of Surgeons. Possible future directions in this area are also briefly summarized.

The effects of propofol on vascular function in mesenteric arteries of the aging rat

Hypotension following administration of propofol, an anesthetic agent, is strongly predicted by advanced age and is partly due to direct vasodilation. We hypothesized that propofol increases nitric oxide (NO)-mediated vasodilation by enhancing its bioavailability in the aged adult vasculature, leading to greater vasodilation than in the young adult. Small mesenteric arteries from rats aged 13–15 versus 3 to 4 mo were compared in this study. Reactivity to propofol (1–100 μM) alone and with the addition of acetylcholine (ACh; 0.1–10 μM) in endothelial-intact and dunuded arteries following phenylephrine constriction was assessed using myography. NG-nitro-l-arginine methyl ester (l-NAME) and meclofenamate (Meclo) were used to inhibit NO and prostaglandin synthesis, respectively. Superoxide dismutase (SOD) and catalase were used as antioxidants during ACh relaxation and were compared with propofol in aging arteries. Propofol alone induced greater relaxation in 1) endothelial-intact compared with denuded arteries and 2) aged compared with young arteries, which were inhibited by l-NAME. ACh-induced relaxation was greater in young compared with aged control arteries; however, propofol pretreatment increased this relaxation in aged but not in young arteries. Additionally, propofol inhibited ACh-induced relaxation in arteries treated with l-NAME + Meclo [relaxation attributed to endothelium-derived hyperpolarizing factor (EDHF)]. Pretreatment with SOD and catalase increased relaxation to ACh in aged arteries similar to propofol. In conclusion, propofol causes relaxation in small mesenteric arteries in an endothelial-dependent and independent manner and increases ACh-induced relaxation in aged arteries. Interestingly, propofol inhibits EDHF-mediated relaxation but increases availability of NO, which leads to overall vascular relaxation.

Monitoring with EEG entropy decreases propofol requirement and maintains cardiovascular stability during induction of anaesthesia in elderly patients

BACKGROUND AND OBJECTIVES

Electroencephalographic entropy is used to measure the degree of brain hypnosis and anaesthesia depth. Two parameters are displayed in the monitor, state entropy (SE) and response entropy (RE). Ageing leads to reduction in liver mass as well as hepatic blood flow, which decreases clearance of propofol and increases the risk of cardiovascular adverse effects. The aim of this study is to demonstrate the effect of electroencephalographic entropy on propofol requirement and haemodynamic parameters during induction of anaesthesia in elderly patients.

METHODS

We studied 72 elderly patients. Standard monitoring was performed for all patients together with entropy monitor. Patients were allocated randomly either to the control group, which were given the recommended induction dose of propofol, or to the entropy group which was induced with propofol based on entropy reading where the end-point was SE 50 and SE-RE difference less than 10. Propofol induction doses and haemodynamic changes were recorded. Anaesthesia was maintained using sevoflurane and O2 air mixture.

RESULTS

After induction of anaesthesia, the systolic, diastolic, mean arterial pressure, RE and SE were significantly lower in the control group (P value < 0.05). Total dose of propofol and the dose kg-1 were significantly reduced by 37.1% and 31.8%, respectively, in the entropy group (P value < 0.01).

CONCLUSION

The use of electroencephalographic entropy during induction of anaesthesia in elderly patients reduces propofol requirements and maintains cardiovascular stability.

Comparison of Propofol and Sevoflurane for Laryngeal Mask Airway Insertion in Elderly Patients

BACKGROUND

Sevoflurane and propofol have been widely used for anesthesia induction. This study compared the efficacies of sevoflurane and propofol inductions for laryngeal mask airway (LMA) insertion in elderly patients.

METHODS

Ninety patients, aged 60 or more, received anesthesia induction with propofol and with sevoflurane 8% using the vital capacity breath (VCB) or tidal volume breath (TVB) techniques. Hemodynamic changes, induction time, complications, and the quality and ease of LMA insertion were observed.

RESULTS

LMA was inserted most, less or least rapidly with propofol (89 +/- 28 s), sevoflurane 8% using the VCB (163 +/- 34 s) or TVB (205 +/- 44 s) techniques, respectively. Anesthesia induction with propofol or sevoflurane 8% using the VCB technique produced either more frequent apnea or greater reduction in mean blood pressure than with sevoflurane 8% using the TVB technique.

CONCLUSIONS

Sevoflurane 8% using the TVB technique provides a smoother induction with a stable hemodynamic profile, less apnea and technical demand, but requiring longer time for LMA insertion in unpremedicated elderly patients.