Does intravenous induction dosing among patients undergoing gastrointestinal surgical procedures follow current recommendations: a study of contemporary practice

Relationship between preinduction electroencephalogram patterns and propofol sensitivity in adult patients

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Pharmacokinetic and Pharmacodynamic Changes in the Elderly: Impact on Anesthetics

Anesthesiologists are increasingly required to care for frail elderly patients. A detailed knowledge of the influence of age on the pharmacokinetics and dynamics of the anesthetic drugs is essential for optimal safety and care. For most of the anesthetic drugs, the elderly need lower doses to achieve the same plasma concentrations, and at any given plasma and effect-site concentration, they will have more profound clinical effects than younger patients. Caution is required, with close monitoring of clinical effects and active titration of dose administration to achieve the desired level of effect, ideally following the "start low, go slow" principle.

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.

Association of propofol induction dose and severe pre-incision hypotension among surgical patients over age 65

STUDY OBJECTIVE

We aimed to study the association between propofol induction dose (mg/kg) and pre-incision severe hypotension (Mean Arterial Pressure (MAP) ≤ 55 mmHg) among patients ≥65 years of age.

DESIGN

Retrospective Observational.

SETTING

40 centers participating in the Multicenter Perioperative Outcomes Group consortium.

PATIENTS

Patients ≥65 years of age undergoing non-cardiac, non-vascular surgery who received propofol for general anesthetic induction prior to endotracheal intubation between January 2014 and December 2018.

INTERVENTIONS

None.

MEASUREMENTS

The primary exposure was total propofol induction dose in mg/kg, and the primary outcome was occurrence of severe hypotension (MAP≤55 mmHg) prior to surgical incision, stratified by non-invasive vs. invasive blood pressure monitoring type.

MAIN RESULTS

Among 320,585 total patients, 22.6% experienced the outcome of pre-incision severe hypotension (MAP≤55 mmHg). When stratified by blood pressure monitoring type, 20.7% with non-invasive blood pressure measurements, and 35.0% with invasive blood pressure measurements had the outcome. After controlling for a variety of patient and procedural factors, there was a significant independent association between propofol induction dose and pre-incision hypotension (Non-invasive blood pressure cohort odds ratio (OR) 1.10; 95% confidence interval (CI) 1.07 to 1.13; p < 0.001; and Invasive blood pressure cohort OR 1.15; 95%CI 1.10 to 1.21; adjusted p < 0.001). The association was robust to alternative definitions of the outcome, including less severe hypotension (MAP≤65 mmHg) and blood pressure drop from baseline as a continuous measure. Although no threshold safe induction dose was identified at which hypotension was avoided, an analysis of propofol dose greater or less than 1.5 mg/kg (i.e. the maximum FDA-defined typical induction dose) demonstrated that doses in excess of the FDAs threshold were positively associated with odds of severe hypotension (Non-invasive cohort: OR 1.05; 95% CI 1.02 to 1.08; p < 0.001; Invasive cohort: OR 1.11; 95%CI 1.05 to 1.17; adjusted p < 0.001).

CONCLUSIONS

In a multicenter cohort of geriatric surgical patients receiving propofol for general anesthetic induction and endotracheal intubation, severe pre-incision hypotension (MAP ≤55 mmHg) that has previously been associated with postoperative morbidity was common. The dose of propofol used was significantly associated with increased odds of this outcome after controlling for a number of clinically relevant factors. Future studies that are designed to test different approaches to anesthesia induction for reducing severe post induction pre-incision hypotension are warranted.

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.

An Analysis of Anesthesia Induction Dosing in Female Older Adults

BACKGROUND/OBJECTIVES

In the context of an aging surgical population, appropriate anesthetic induction dose adjustments for the older adult remain poorly defined. In the present study, we describe the prevalence of excess induction agent dose in reference to US Food and Drug Administration (FDA) guidance and seek to investigate the possible association of such excess dose with postinduction hypotension and postoperative acute kidney injury (AKI).

STUDY DESIGN

A retrospective observational study was conducted in a large tertiary teaching hospital in accordance with our a priori analytic protocol as registered on ClinicalTrials.gov (NCT03699696). For inclusion, patients had to be 65 years or older and to have received general anesthesia with propofol induction for gynecologic oncology surgery between December 1, 2014 and July 8, 2018. Descriptive variables of the patients, machine-captured perioperative vital signs, induction anesthetic, and vasopressor/inotrope administrations were recorded.

MAIN OUTCOME MEASURES

A total of 541 female patients met inclusion criteria. The mean (standard deviation) age of the cohort was 72.20 (5.93) years. Regarding the primary outcome, 65.43% (354 patients, 95% confidence interval 61.2-69.4) of the cohort received more than the FDA recommended 1-1.5 mg/kg induction dose for patients of advanced age undergoing general anesthesia.

RESULTS

The percentage of patients receiving doses in excess of the FDA guidance remained substantial across all age groups, but decreased progressively with increasing 5-year age intervals (from 74% among those aged 65-69 years to 44% among those aged > 80 years). Excess propofol dose in the present cohort was not associated with our a priori definition of postinduction hypotension. Regarding AKI, among the 30 patients suffering this outcome, it occurred less often in patients who received higher propofol doses (4.1% [9/217] vs. 15.3% [21/138], p < 0.001), a result that may have been confounded by differential rates of missingness.

CONCLUSIONS

Older adults commonly receive propofol induction doses in excess of the FDA guidance. The immediate hemodynamic effects of these doses on postinduction hypotension were not seen in the present cohort, suggesting that propofol dose adjustments may serve as a marker of physicians' judgments as to the frailty of patients. The relevance of the AKI association is difficult to interpret due to the non-differential missingness of AKI data between the two groups.

Effect of a Cognitive Aid on Reducing Sugammadex Use and Associated Costs: A Time Series Analysis

BACKGROUND

The authors observed increased pharmaceutical costs after the introduction of sugammadex in our institution. After a request to decrease sugammadex use, the authors implemented a cognitive aid to help choose between reversal agents. The purpose of this study was to determine if sugammadex use changed after cognitive aid implementation. The authors' hypothesis was that sugammadex use and associated costs would decrease.

METHODS

A cognitive aid suggesting reversal agent doses based on train-of-four count was developed. It was included with each dispensed reversal agent set and in medication dispensing cabinet bins containing reversal agents. An interrupted time series analysis was performed using pharmaceutical invoices and anesthesia records. The primary outcome was the number of sugammadex administrations. Secondary outcomes included total pharmaceutical acquisition costs of neuromuscular blocking drugs and reversal agents, adverse respiratory events, emergence duration, and number of neuromuscular blocking drug administrations.

RESULTS

Before cognitive aid implementation, the number of sugammadex administrations was increasing at a monthly rate of 20 per 1,000 general anesthetics (P < 0.001). Afterward, the monthly rate was 4 per 1,000 general anesthetics (P = 0.361). One month after cognitive aid implementation, the number of sugammadex administrations decreased by 281 per 1,000 general anesthetics (95% CI, 228 to 333, P < 0.001). In the final study month, there were 509 fewer sugammadex administrations than predicted per 1,000 general anesthetics (95% CI, 366 to 653; P < 0.0001), and total pharmaceutical acquisition costs per 1,000 general anesthetics were $11,947 less than predicted (95% CI, $4,043 to $19,851; P = 0.003). There was no significant change in adverse respiratory events, emergence duration, or administrations of rocuronium, vecuronium, or atracurium. In the final month, there were 75 more suxamethonium administrations than predicted per 1,000 general anesthetics (95% CI, 32 to 119; P = 0.0008).

CONCLUSIONS

Cognitive aid implementation to choose between reversal agents was associated with a decrease in sugammadex use and acquisition costs.

Aged mice show an increased mortality after anesthesia with a standard dose of ketamine/xylazine

Geriatric animal models are crucial for a better understanding and an improved therapy of age-related diseases. We observed a high mortality of aged mice after anesthesia with a standard dose of ketamine/xylazine, an anesthetic regimen frequently used in laboratory veterinary medicine.

C57BL/6-N mice at the age of 2.14 ± 0.23 months (young mice) and 26.31 ± 2.15 months (aged mice) were anesthetized by intraperitoneal injection of 2 mg ketamine and 0.2 mg xylazine. 4 of 26 aged mice (15.4%) but none of 26 young mice died within 15 min after injection of the anesthetics. The weight of aged mice was significantly higher than that of young mice (32.8 ± 5.4 g versus 23.2 ± 3.4 g, p < 0.0001). Thus, aged mice received lower doses of anesthetics in relation to their body weight which are within the lower range of doses recommended in the literature or even beneath. There were no differences between deceased and surviving aged mice concerning their sex, weight and their motor performance prior to anesthesia.

Our data clearly show an age-related increase of mortality upon anesthesia with low standard doses of ketamine/xylazine. Assessment of weight and motor performance did not help to predict vulnerability of aged mice to the anesthetics. Caution is necessary when this common anesthetic regimen is applied in aged mice: lower doses or the use of alternative anesthetics should be considered to avoid unexpected mortality.

The present data from our geriatric mouse model strongly corroborate an age-adjusted reduction of anesthetic doses to reduce anesthesia-related mortality in aged individuals.

A Retrospective Observational Study of Anesthetic Induction Dosing Practices in Female Elderly Surgical Patients: Are We Overdosing Older Patients?

BACKGROUND/OBJECTIVES

Despite guidelines suggesting a 25-50 % reduction in induction doses of intravenous anesthetic agents in the elderly (≥65 years), we hypothesized that practitioners were not sufficiently correcting drug administration for age, contributing to an increased incidence of hypotension in older patients undergoing general anesthesia.

STUDY DESIGN

We conducted a retrospective, observational study in a tertiary-care academic hospital. The study included 768 female patients undergoing gynecologic surgeries who received propofol-based induction of general anesthesia.

MAIN OUTCOME MEASURES

Weight-adjusted anesthetic induction dosing, age-associated differences in dosing by ASA-PS (American Society of Anesthesiology-Physical Status), and hemodynamic outcomes between younger (18-64 years, n = 537) and older (≥65 years, n = 231) female patients were analyzed.

RESULTS

Older patients received lower doses of propofol and midazolam than younger patients (propofol: 2.037 ± 0.783 vs 2.322 ± 0.834 mg/kg, p < 0.001; midazolam: 0.013 ± 0.014 vs 0.023 ± 0.042 mg/kg, p < 0.001). However, practitioners still consistently exceeded the FDA recommended dose (1-1.5 mg/kg) of propofol for elderly patients. There was no significant difference in the doses of fentanyl administered between the two age groups (1.343 ± 0.744 vs 1.363 ± 0.763 μg/kg, p = 0.744), and doses of fentanyl in older patients exceeded the recommended dose (0.5-1.0 μg/kg). Corresponding to observed overdosing of induction agents, older patients experienced larger decreases in post-induction blood pressure and were more likely to receive vasopressor therapy.

CONCLUSIONS

Anesthetic induction doses of fentanyl and propofol were not sufficiently corrected in older patients in accordance with recommendations. Significantly greater frequency of post-induction hypotension occurred amongst older patients. Quality improvement efforts may lead to improved outcomes in this vulnerable population.

A Pilot Analysis of the Association Between Types of Monitored Anesthesia Care Drugs and Outcomes in Transfemoral Aortic Valve Replacement Performed Without General Anesthesia

OBJECTIVE

The types of agents used for monitored anesthesia care (MAC) and their possible differential effects on outcomes have received less study despite increased use over general anesthesia (GA) in transfemoral aortic valve replacements (TAVRs). In this pilot analysis of patients undergoing TAVR using MAC, the authors described the anesthetic agents used and sought to investigate the possible association of anesthetic agent choice with outcomes and the extent to which total weight and time-adjusted doses of anesthetics declined with increasing 10-year age increments.

DESIGN

Retrospective observational study.

SETTING

Tertiary teaching hospital.

PARTICIPANTS

Ninety-three participants scheduled to undergo TAVR, with a primary plan of conscious sedation between November 2014 and June 2016, were included.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Types of MAC were divided into 4 primary groups, but 2 groups were focused: propofol (n = 39) and dexmedetomidine plus propofol (n = 34). Conversion to GA occurred in 6 participants (6.45%) and was not associated with the type of sedation received. The authors also compared patients who received dexmedetomidine with those who did not in accordance with their a priori analytic plan. There were no associations between the use of dexmedetomidine and postoperative delirium or intensive care unit/hospital length of stay. No significant trends in medication dose adjustments were seen across increasing 10-year age increments.

CONCLUSIONS

A wide breadth of MAC medications is in use among TAVR patients and does not support differences in outcomes. Despite recommendations to reduce anesthetic drug dosing in the elderly, no significant trends in dose reduction with increasing age were noted.