The aim of this study is to know the characteristic of "one-per-mil" tumescent solution in regards of the optimal time delay to achieve optimal visualization of operation field in hand and digit surgery.

Hypothesis:

1. Epinephine in "one-per-mil" concentration by tumescent injection technique will provide faster decrease in oxygen saturation compared to normal saline solution injected by tumescent technique.
2. Epinephrine in "one-per-mil" concentration by tumescent injection technique will provide effectiveness in vasoconstriction longer than 10 minutes as the optimal time delay.
3. Epinephine in "one-per-mil" concentration by tumescent injection technique causes no finger necrosis as normal saline solution injected by tumescent technique.

This is a prospective, randomized, double-blind study to measure the optimal time delay of 1:1,000,000 epinephrine in saline solution injected by tumescent technique until maximum vasocontriction in the distal finger is achieved.

Subjects will be injected in both his ring fingers(distal phalanges, volar side) with randomized solutions, one containing "one-per-mil" tumescent solution and the other containing only normal saline solution; information which both the injector and examiner are blinded from. Maximum vasoconstriction of the finger injected is depicted by the lowest oxygen saturation (recorded every minute until 45 minutes using pulse oxymeter).

Inclusion Criteria:

• Willing to join the research
• BMI 18.5-23
• Healthy individual, no history of blood or coagulation disorders

Exclusion Criteria:

• BMI <18.5 or >23
• History of blood or coagulation disorder, diabetes mellitus, heavy smoker