Effects of a flash of light in different colors on venous cannulation pain: a randomized, controlled trial

To determine the effects of a flash of light in different colors on the frequency and severity of pain during venous cannulation.

Double-blinded, randomized controlled study.

Operating room of a university hospital.

120 adult, ASA physical status 1 and 2 patients undergoing elective surgery,

Patients were allocated to 4 groups. Patients' faces were photographed with a camera without first receiving a flash of light (control group), with a flash of white light (white group), a flash of blue light (blue group), or a flash of red light (red group). With a 20-gauge cannula, a vein on the dorsum of the nondominant hand was cannulated immediately after a flash of light.

Severity of pain was measured by Visual Analog Scale (VAS), Verbal Rating Scale (VRS), and FACES Pain Scale (FPS), and frequencies were compared.

The blue group had the lowest pain scores as measured by VAS, followed by the red group, then the white group, all lower than the control group (0.9 ± 0.61, 1.37 ± 0.67, 2.4 ± 1.13, and 4.63 ± 1.5, respectively; P < 0.01). The same pattern emerged regarding frequency of pain (13.3%, 40%, 80% and 100%, respectively; P < 0.01). As for severity of pain measured by VRS and FPS, all intergroup comparisons were significant except for the red and blue groups.

Application of a blue light flash before venous cannulation decreased the frequency and severity of pain associated with venipuncture. This method is an effective, easy to perform, and inexpensive way to reduce pain during venous cannulation.