Preoperative Ephedrine Attenuates the Hemodynamic Responses of Propofol During Valve Surgery: A Dose Dependent Study

Summary

The prophylactic use of small doses of ephedrine may be effective in obtunding of the hypotension responses to propofol with minimal hemodynamic and ST segment changes. The investigators aimed to evaluate the effects of small doses of ephedrine on hemodynamic responses of propofol anesthesia for valve surgery.

There is widespread interest in the use of propofol for the induction and maintenance of anesthesia for fast track cardiac surgery. However, its use for induction of anesthesia is often associated with a significant rate related transient hypotension for 5-10 minutes. This is mainly mediated with decrease in sympathetic activity with minor contribution of its direct vascular smooth muscle relaxation and direct negative inotropic effects.

Ephedrine has demonstrated as a vasopressor drug for the treatment of hypotension in association with spinal and general anesthesia. Prophylactic use of high doses of ephedrine \[10-30 mg\] was effective in obtunding the hypotensive response to propofol with associated marked tachycardia. However, the use of smaller doses (0.1-0.2 mg/kg) was successfully attenuated, but not abolished, the decrease in blood pressure with transient increase in heart rate. This vasopressor effect is mostly mediated by β-stimulation rather than α-stimulation and also indirectly by releasing endogenous norepinephrine from sympathetic nerves.

Because the effect of decreasing the dose of ephedrine from 0.1 to 0.07 mg/kg may be clinically insignificant, the investigators postulated that the prophylactic use of small dose of ephedrine may prevent propofol-induced hypotension after induction of anesthesia for valve surgery with minimal in hemodynamic, ST segment, and troponin I changes.

The aim of the present study was to investigate the effects of pre-induction administration of 0.07, 0.1, 0.15 mg/kg of ephedrine on heart rate (HR), mean arterial blood pressure (MAP), central venous and pulmonary artery occlusion pressures (CVP and PAOP, respectively), cardiac (CI), stroke volume (SVI), systemic and pulmonary vascular resistance (SVRI and PVRI, respectively), left and right ventricular stroke work (LVSWI and RVSWI, respectively) indices, ST segment, and cardiac troponin I (cTnI) changes in the patients anesthetized with propofol-fentanyl for valve surgery.

Conditions

• Hypotension
• Valve Surgery

Interventions

DRUG

Ephedrine

Subjects were allocated randomly to five groups by drawing sequentially numbered sealed opaque envelopes containing a computer-generated randomization code. The subjects received intravenous injection of 0.1 mL/kg of a study solution containing either saline 0.9% solution \[group 1 (n=30)\], ephedrine 0.7 mg/mL \[group 2 (n=30)\], ephedrine 1 mg/mL \[group 3 (n=30)\] or ephedrine 1.5 mg/mL \[group 4 (n=30)\]or phenylephrine 15 mcg/mL \[group 5 (n=30)\]. All study solutions were injected over 1 min at 1 min before induction of anesthesia. The placebo and the ephedrine solutions were prepared in identical syringes labeled 'study drug' by the local pharmacy department before induction of anesthesia.

DRUG

Placebo

Subjects were allocated randomly to five groups by drawing sequentially numbered sealed opaque envelopes containing a computer-generated randomization code. The subjects received intravenous injection of 0.1 mL/kg of a study solution containing either saline 0.9% solution \[group 1 (n=30)\], ephedrine 0.7 mg/mL \[group 2 (n=30)\], ephedrine 1 mg/mL \[group 3 (n=30)\] or ephedrine 1.5 mg/mL \[group 4 (n=30)\]or phenylephrine 15 mcg/mL \[group 5 (n=30)\]. All study solutions were injected over 1 min at 1 min before induction of anesthesia. The placebo and the ephedrine solutions were prepared in identical syringes labeled 'study drug' by the local pharmacy department before induction of anesthesia.

DRUG

Phenylephrine

Subjects were allocated randomly to five groups by drawing sequentially numbered sealed opaque envelopes containing a computer-generated randomization code. The subjects received intravenous injection of 0.1 mL/kg of a study solution containing 15 mcg/ml of phenylephrine \[group 5 (n=30)\] All study solutions were injected over 1 min at 1 min before induction of anesthesia. The placebo, the ephedrine, and the phenylephrine solutions were prepared in identical syringes labeled 'study drug' by the local pharmacy department before induction of anesthesia.

Sponsors & Collaborators

• Mansoura University

  collaborator OTHER

• King Faisal University

  lead OTHER

Principal Investigators

• Mohamed R El Tahan, M.D · King Faisal University

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

55 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2004-03-31

Primary Completion

2009-06-30

Completion

2010-03-31

Countries

• Egypt
• Saudi Arabia

Study Locations