What is the clinical evidence from this study?

Study design: RCT. Population: Hypertension requiring angiotensin axis blockade (n=45). Intervention: Methohexital vs. Propofol (2.5 mg/kg). Primary outcome: Incidence of hypotension (SBP 30% decrease from baseline) (RR 2.10, 95% CI 1.20-3.69, p=0.01).

January 31, 2019Medicine7 citationsOpen Access

A randomized controlled trial comparing methohexital and propofol for induction in patients receiving angiotensin axis blockade

ABAnthony Bonavia TVThomas A. Verbeek SASanjib Das Adhikary

Key Result

Anesthetic induction with methohexital significantly reduced the incidence of hypotension compared to propofol (40% vs 84%, p=0.01) in hypertensive patients receiving angiotensin axis blockade.

Study Design

Type

RCT (n=45)

Blinding

Open-label

Randomization

Stratified by gender and use of ACEi versus ARB

Multicenter

Structured PICO

Does methohexital improve hemodynamic stability compared to propofol during anesthetic induction in adult hypertensive patients taking ACEi or ARB?

Population

45 adult hypertensive patients taking ACE inhibitors or angiotensin receptor blockers undergoing elective noncardiac surgery, followed for 15 minutes post-induction.

Intervention

Methohexital for anesthetic induction (equi-anesthetic dose)

Comparator

Propofol for anesthetic induction (equi-anesthetic dose)

Outcome

Hemodynamic profile (degree of hypotension) during anesthetic inductionsurrogate

Methohexital provides better hemodynamic stability than propofol during anesthetic induction in hypertensive patients on chronic angiotensin axis blockade.

Main Result

Relative Risk: 2.1 (95% CI 1.2–3.69)

Absolute Event Rate: 40% vs 84%

Absolute Risk Reduction: 44%

p-value: p=0.01

Limitations

Baseline blood pressure was determined before anesthetic induction rather than using outpatient measurements.
Unblinded study design necessitated a more stringent definition of hypotension to avoid treatment bias.
Study was prematurely stopped following an interim analysis due to high costs and low likelihood of demonstrating neurohormonal differences.

Abstract

BACKGROUND: Pharmacologic angiotensin axis blockade (AAB) has been associated with profound hypotension following anesthetic induction with propofol. To combat this problem, investigators have attempted to withhold angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB) preoperatively, or evaluated the effects of different induction agents in conferring greater hemodynamic stability. To date, methohexital has not been compared with the most commonly used induction agent, propofol. Hence, the primary objective was to study the hypothesis that methohexital confers a better hemodynamic profile than propofol for anesthetic induction, in patients receiving AAB. The secondary objective was to investigate the postinduction levels of serum neurohormones in an attempt to explain the mechanisms involved. METHODS: Forty-five adult, hypertensive patients taking ACEi or ARB and scheduled for elective, noncardiac surgery completed the study. Patients were randomized to receive equi-anesthetic doses of either propofol or methohexital for anesthetic induction. Hemodynamic variables were measured and blood samples were drawn before induction and for 15 minutes afterwards. RESULTS: Methohexital resulted in less hypotension compared with propofol (P = .01), although the degree of refractory hypotension was similar (P = .37). The postinduction systolic blood pressure (P = .03), diastolic blood pressure (P < .001) and heart rate (P = .03) were significantly higher in the methohexital group. A nonsignificant elevation of serum norepinephrine and epinephrine levels was observed in the methohexital group, while serum arginine vasopressin and angiotensin II levels did not differ between groups. CONCLUSION: While methohexital was shown to confer greater hemodynamic stability in patients taking ACEi/ARB, the measured hormone levels could not explain the mechanism for this effect.

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