Original contributionDose-dependent hemodynamic effects of propofol induction following brotizolam premedication in hypertensive patients taking angiotensin-converting enzyme inhibitors☆,☆☆
Introduction
Perioperative administration of angiotensin-converting enzyme inhibitors (ACEIs) may be beneficial as they attenuate the adrenergic response to stressful stimuli in a variety of patients undergoing cardiac [1], gynecological [2], vascular [3], and cerebrovascular [4] surgeries and in patients with impaired left ventricular (LV) function [4]. Patients taking ACEIs may require more vasopressors to maintain adequate blood pressure (BP) [5], [6], and are reportedly at special risk of intraoperative hypotension, especially after anesthetic induction [7], [8]. Profound bradycardia and hypotension have been described following spinal anesthesia in a patient receiving an ACE inhibitor [9].
Some investigators recommend that ACEIs be continued [1], [10] before anesthesia while others advise that they be discontinued [7]. Hypotension resistant to pressors, especially during induction of general anesthesia, is the most feared potential complication of continuing ACEI administration.
The most probable mechanism for post-induction hypotension associated with perioperative continuation of chronic ACEI treatment is increased cardiovascular sensitivity to anesthetic induction agents [11]. To the extent that this mechanism applies, it may simply be sufficient to reduce induction agent doses in patients taking ACEIs. The hemodynamic and heart rate (HR) responses to various induction doses of propofol in patients taking ACEIs were evaluated to determine the induction dose of propofol with the lowest frequency of hemodynamic changes.
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Materials and methods
With approval of the Institutional Review Board of the Edith Wolfson Medical Center, a total of 88 hypertensive patients with well-preserved LV function [ejection fraction (EF) > 45%] who were taking ACEIs for at least 6 weeks were enrolled in the study [10]. Ancillary antihypertensives, including beta-blockers, were permitted. All patients were ASA physical status II or III, aged 40 to 65 years, and scheduled for elective abdominal surgery with general anesthesia. Patients were excluded from
Results
Baseline characteristics and intraoperative outcomes are univariably summarized in Table 1; patients in the lower propofol dose groups were significantly taller and heavier, though body mass index (BMI) did not significantly differ among the groups. No patient complained of awareness during anesthesia.
Median (Q1, Q3) pharmacologic intervention counts were 0 (0,3), 2 (0,2), 1 (0,5), and 1 (1,3) for the 1.3, 1.6, 2.0, and 2.3 mg/kg propofol dose groups, respectively. Because not all covariables
Discussion
We evaluated the hemodynamic responses to various propofol induction doses in patients chronically taking ACEIs. Interestingly, mean and lowest HRs were generally similar over the range of induction doses spanning 1.3 to 2.3 mg/kg. Average and lowest MAPs also were generally similar over the tested dose range. Nonetheless, our model indicated that a propofol dose of 1.3 mg/kg—the lowest dose used in this study—requires the smallest number of interventions for hypotension or bradycardia during
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Cited by (0)
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Supported by the Joseph Drown Foundation, Los Angeles, CA. The sponsor was not involved in study design, data acquisition or analysis, oor manuscript preparation.
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No co-author had any financial interest in this research.