An Analysis of Anesthesia Induction Dosing in Female Older Adults

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.

Hemodynamic effects of a low versus a high dose of propofol during induction of anesthesia. A randomized trial

BACKGROUND

Hypotension is common after anesthesia induction with propofol and is associated with increased morbidity. It is important to examine the effects of the proposed interventions to limit preventable hypotension, as suggested by the reduction in the dose of propofol. Our objective was to investigate whether a high dose of propofol is inferior to a low dose with respect to changes in systolic arterial blood pressure (SAP).

METHODS

This randomized, double-blind, dose-controlled, non-inferiority study included 68 healthy women scheduled for gynecological surgery at the Day Surgery Unit, Haugesund Hospital, Norway. The patients were randomly allocated 1:1 to a low or high dose (1.4 mg/kg total body weight (TBW) versus 2.7 mg/kg TBW of propofol corresponding to maximal effect site concentrations (Ce) of 2.0 μg/mL versus 4.0 μg/mL. The dose of remifentanil was 1.9-2.0 μg/kg TBW, with maximal Ce of 5.0 ng/mL. The patients were observed for 450 s from the start of the infusions. The first 150 s was the sedation period, after which a bolus of propofol and remifentanil was administered. Baseline was defined as 55-5 s before the bolus doses. LiDCOplus was used for invasive beat-to-beat hemodynamic monitoring of changes in SAP, heart rate (HR), cardiac output (CO), stroke volume (SV), and systemic vascular resistance (SVR). A difference of 10 mmHg in the change in SAP was considered to be clinically important.

RESULTS

The SAP change difference for low versus high dose was -2.9 mmHg (95% CI -9.0-3.1). The relative changes for low versus high dose were SAP -31% versus -36%, (p < .01); HR -24% versus -20%, (p = .09); SVR -20% versus -31%, (p < .001); SV -16% versus -20%, (p = .04); and CO -35% versus -32%, (p = .33).

CONCLUSION

A high dose of propofol was not inferior to a low dose, and a reduction in the dose of propofol did not result in clinically important attenuation of major hemodynamic changes during induction in healthy women.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT03861364, January 3, 2019.

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.

Comparison of noninvasive continuous arterial blood pressure measured by NICAP with arterial line in elderly patients

BACKGROUND

Non-Invasive Continuous Arterial Pressure system (NICAP) allows continuous monitoring, timely detection of hypotension, and avoiding risks from invasive procedures. A previous study showed good comparability of NICAP with arterial line in people with no evidence of cardiovascular disease. Therefore, the goal of this study was to investigate whether NICAP could be accurately applied to elderly patients.

METHODS

In this single-centered observational study, forty-one patients above 65 undergoing elective surgeries requiring artery catheterizations were enrolled from July 17, 2020, to June 25, 2021. Radial artery cannulation and NICAP monitoring were started before anesthesia. Blood pressure during the anesthesia induction and the whole surgery, trend of blood pressure changes, time needed for establishing continuous monitoring, and complications were recorded.

RESULTS

A total of 6751 valid pairs of blood pressure measurements were analyzed. In the Bland-Altman analysis, the arithmetic means for systolic, diastolic, and mean arterial pressure were 2.2, 3.3, and 2.8 mmHg, respectively. NICAP and arterial line correlation coefficients for systolic, diastolic, and mean arterial pressure were 0.49, 0.33, and 0.45, respectively. In the trending analysis, the polar concordance rates at 30 degrees were 70.9% for systolic, 67.7% for diastolic, and 69.3% for mean arterial blood pressure. During the anesthesia induction, the arithmetic means for systolic, diastolic, and mean arterial pressure in the Bland-Altman analysis were 1.7, -0.2, and 0.5 mmHg, respectively. NICAP and arterial line correlation coefficients for systolic, diastolic, and mean arterial pressure were 0.78, 0.61 and 0.75, respectively. No severe complications occurred.

CONCLUSIONS

NICAP has a poor correlation with the arterial line in elderly patients for the whole surgery or during anesthesia induction. Moreover, it showed poor comparability in the detection of blood pressure change trends with arterial lines. Our findings suggest that NICAP might not be sufficiently accurate to be applied clinically in elderly patients with comorbidities. More accurate calibration and iteration are needed.

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.