RESUMO
Arterial cannulation through the standard skin wheal of local anesthetic raised with a needle may be painful. The authors compared the efficacy of local anesthetic injected via a 25G needle versus a Bioject jet injector for arterial cannulation in awake neurosurgical patients. After institutional review board approval, 40 patients were randomized to receive 0.3 mL 1% lidocaine adjusted to pH 7.0 with NaHCO3 by Bioject with a 2-cm spacer between the syringe and skin or by 25G needle injection. Two pain assessments were used at the time of local anesthetic injection and at arterial cannulation. Patients rated their pain on a visual analog scale (VAS) (0 = no pain, 100 = worst pain). Observers scored patient response as 0 (no response), 1 (flinch), or 2 (withdrawal). The VAS at injection was 23 +/- 19 for the needle group and 3 +/- 6 for the Bioject group (P < 0.001). The VAS at arterial cannulation was 39 +/- 25 for the needle group and 15 +/- 22 for the Bioject group (P < 0.001). Median observer scores at injection and cannulation were 1 (range 0-2) for the needle group and 0 (range 0-2) for the Bioject group (P < 0.001). Patients in the Bioject group experienced significantly less pain during lidocaine administration and at the time of arterial cannulation by their own and by an observer's assessment than the needle injection group. Jet injection of local anesthetic should be considered prior to arterial cannulation in awake patients.