Lightwand intubation does not reduce the increase in intraocular pressure associated with tracheal intubation

To evaluate the changes in hemodynamic variables and intraocular pressure (IOP) after tracheal intubation using either lightwand or direct-vision laryngoscopy techniques.

Prospective, randomized study.

Inpatient anesthesia at a University Anesthesia Department.

50 normotensive, ASA physical status I and II patients, without ocular or cardiovascular diseases, and with a Mallampati score no greater than 2.

After intravenous (i.v.) midazolam premedication (0.05 mg.kg-1), general anesthesia was induced with fentanyl (1 microgram.g-1) and thiopental sodium (5 mg.g-1) followed by vecuronium bromide (0.1 mg.g-1), then patients were randomly allocated to receive either the lightwand (Trachlight, n = 25) or direct-vision laryngoscopy (Laryngoscopy, n = 25) intubating techniques. General anesthesia was maintained with 1% isoflurane and 60% nitrous oxide in oxygen mixture for 5 minutes.

Baseline hemodynamic variables were recorded 10 minutes after i.v. premedication, and then every minute after tracheal intubation. Intraocular pressure measurements were performed by means of a computerized indentation tonometer after general anesthesia induction and then 1 and 5 minutes after tracheal intubation. In both groups, mean arterial blood pressure and heart rate increased from baseline, without differences between the two groups. One minute after intubation, IOP increased in both groups: the mean percentage increase was 32% in the Laryngoscopy group and 16% in the Trachlight group. However, this difference was not statistically significant. Five minutes after intubation, IOP decreased to baseline values in both groups.

We conclude that in healthy patients without ocular disease, using a lightwand intubating technique does not reduce the hemodynamic responses and increase in IOP associated with tracheal intubation as compared with conventional direct-vision laryngoscopy.