[Comparative study of clonidine and lidocaine on the attenuation of the intraocular pressure increase associated with laryngoscopy and endotracheal intubation].

OBJECTIVE

To verify and compare the efficacy of clonidine and lidocaine for attenuating the ocular hypertensive response generated by manipulation of the laryngoscope and endotracheal intubation (EIT).

PATIENTS AND METHODS

In this prospective double blind study 45 patients undergoing non-ocular surgery were divided into 3 groups according to pretreatment protocol: A, approximately 3 micrograms/kg clonidine orally 90-120 min before surgery; B, 1.5 mg/kg intravenous lidocaine 1 min before EIT and C, control group. On all patients we recorded intraocular pressure (IOP), mean arterial pressure and heart rate at the following times: basal, just before EIT, immediately after EIT, 5 minutes later and 10 minutes later.

RESULTS

The patients pretreated with clonidine had significantly lower IOP levels than did the control group at all measurements times; patients pretreated with lidocaine had lower IOP after induction and after intubation. IOP was significantly lower in patients who received lidocaine than in control group patients after EIT, although IOP levels with lidocaine were higher than with clonidine.

CONCLUSIONS

Pretreatment with oral clonidine is an effective method for preventing increases in IOP after EIT, is more effective than pretreatment with lidocaine, and should therefore be used for that end. Intravenous lidocaine represents a valid alternative in emergency cases when the approximate wait time of 2 hours is contraindicated.