This study was enrolled on 9 normal, healthy volunteers, who were junior medical residents and whose hands had suffered no nerve trauma or disease. The mean age of the 7 male and 2 female volunteers was 26 (range 20–37) years. The protocol of this study and informed consent conformed to the ethical guidelines of the 1975 Declaration of Helsinki. The study was explained to the volunteers, who signed a consent form and were reimbursed for their time.
mL solution of 1.0% Xylocaine (Lidocaine, AstraZeneca, Japan) and a 3.0
mL solution of 1.0% Xylocaine with (1
100,000) epinephrine (Lidocaine, AstraZeneca, Japan) were prepared at room temperature. The solutions were injected into the subcutaneous space at the middle point of the palmar digital crease of the 18 middle fingers of the 9 volunteers using a 5
mL syringe and a 27-gauge needle (). A 3.0
mL 1.0% Lidocaine was injected in 9 right middle fingers, and a 3.0
mL 1.0% Lidocaine with (1
100,000) epinephrine was injected into the left middle fingers.
Subcutaneous single injection at the middle point of the palmar digital crease.
The subjects themselves determined the loss of pinprick sensation and its reappearance at their fingertip (palmar distal) every ten seconds up to 60 minutes and each 10 minutes after 60 minutes using the contralateral hand of the injected side. The time to the loss and reappearance of the sensation was measured by the authors using a stopwatch.
The extent of anesthesia was also determined using the pinprick test by the subjects themselves, and they finished at the time when normal sensation was recovered. The extent of anesthesia was recorded by the authors. Each middle finger was divided into 6 zones; the palmar and dorsal areas of the distal segment, middle segment, and proximal segment corresponding to the two surfaces and the three phalangeal segments of the finger [8
The circulation in the fingers was measured using Pulse Oximeter NPB-40 (COVIDIEN Japan Co., Ltd., Japan) before the digital blocks and at 0.5, 1, 3, 5, 10, 20, 30, 60 minutes after digital blocks.
The data are presented as the mean ± SD. Student's t
-test was used to compare the mean variables using the Stat View 5.0 for Windows software package (SAS Institute, USA). The level of significance was set atP