Comparison of Two Techniques of IV Lidocaine on Propofol Injection Pain

The investigators expect that tourniquet lidocaine is superior to straight non-tourniquet lidocaine in reducing propofol injection pain. The investigators also wanted to determine the association of tourniquet duration on reduction of pain with propofol administration. Small studies indicate that 60 seconds of tourniquet lidocaine is superior to 30 seconds or less of tourniquet duration or mixed lidocaine/propofol for injection. The investigators suspect many clinicians do not use the 60-second tourniquet technique due to the extra time involved but hypothesize that a more practical application by applying the tourniquet as soon as the patient is positioned on the operating table will not only be more widely adopted by clinicians as it does not cause delay but also provide the necessary amount of time for benefit from the tourniquet. The investigators also wanted to record the time from tourniquet application to start of propofol administration, which the investigators predict would be at least 60 seconds to see if there is a correlation between duration of venous stasis of IV lidocaine and pain benefit.

Methods and Measures

Design This was conducted as a randomized controlled trial of two methods of administering lidocaine prior to propofol injection.

Setting The study setting was located within North Carolina Baptist Health, an academic medical center, in the Endoscopy Suite or Outpatient Surgery Center where subjects were scheduled to receive propofol as part of their sedation or anesthetic.

Sample Size The investigators estimated that 25 subjects in each of the two groups was required to test the hypothesis based on prior studies.

Interventions and Interactions

The investigators used two groups:

• Group 1: 50mg of 2% lidocaine given just prior to the propofol dose through the IV line.
• Group 2: 50mg of 2% lidocaine given IV with venous occlusion applied when the patient is positioned on the operating room table and timed until the onset of propofol administration. The tourniquet the investigators used was a Quick Release tourniquet applied to the forearm 10cm distal to the elbow joint in the tourniquet group. Venous stasis was confirmed with cessation of flow from hanging IV fluid.

For both groups, no premedication was given, which is the normal practice for these procedures. Study procedures involved placing a 20 gauge intravenous (IV) catheter in a vein distal to the mid forearm. Venous occlusion was achieved by either a latex free tourniquet or McKesson Quick Release tourniquet applied to the forearm 10cm distal to the elbow joint. Tourniquet pressure was somewhat variable but sufficient to cause venous stasis as confirmed by no flow of hanging IV fluid. Injections were delivered at roughly 1 ml/sec.

Schedule of events in the study (all performed by 1 of the 2 investigators:

• Day of procedure: holding area

• Consent subject for study participation
• Randomly assign patient to one of two groups
• Day of procedure: procedure area

-Accompany subject to the operating or procedure room, perform protocol from the group to which the subjects were assigned, while noting outcome measures such as self-described discomfort and observer graded discomfort

• Day of procedure: recovery area

-Revisit subject in recovery 30 minutes after their procedure to determine post-procedure recall of discomfort

• Post-study period
• Analyze data

Analytical Plan The investigators will analyze results initially using descriptive statistics. Comparison between groups was done using chi square tests for proportions, and t-tests or ANOVA procedures for continuous variables. Regression analysis was performed to identify independent outcome predictors. Other inferential statistical analysis was conducted as appropriate.

Informed Consent One of the two investigators obtained signed informed consent from each subject. This was performed in the holding room prior to the procedure since most subjects had their pre-procedure examination performed in the holding room and were not seen prior to the day of their procedure.

Inclusion criteria

• Any subject at North Carolina Baptist Hospital scheduled for a procedure in which they will receive propofol for sedation or anesthesia and will not be receiving any other medications prior to the propofol injection.
• Cases must be schedule to have a duration less than 60 minutes.

Exclusion criteria

• Subjects are excluded if they cannot verbalize a rating of pain
• Subjects are excluded if they require intravenous medications prior to the study period