Pain on injection of propofol: a comparison of methylene blue and lidocaine

Abstract

Study objective: To investigate whether methylene blue, given before injection of propofol, was effective in reducing the frequency and severity of pain associated with propofol injection.

Design: Prospective, randomized, double-blinded clinical study.

Setting: Operating room of a university hospital.

Patients: 90 adult, ASA physical status 1 and 2 patients undergoing elective surgery.

Interventions: Patients were randomly allocated to one of three groups of 30 patients each. Group I received 50 mg of methylene blue, Group II received 40 mg of lidocaine, and Group III, the control group, was given normal saline. All drugs were given as a 2.0 mL bolus 45 seconds before propofol administration.

Measurements: Injection pain using vocal responses, facial grimacing, arm withdrawal, tears, and questioning of the patient were noted. A 4-point scale was used for documenting pain.

Main results: Pain frequency was 90% in the saline group, whereas the frequencies were significantly lower in the lidocaine and methylene blue groups (26.7% and 40%, respectively).

Conclusions: Intravenous pretreatment with methylene blue appears to be effective in reducing the pain during propofol injection.