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

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.