The preoperative evaluation including sampling blood in pediatric patients is hard to perform. However, the knowledge of the baseline cell blood count is important to prepare unexpected surgical bleeding etc.. The invasive procedure for blood sampling in small children is often failed and sometimes induces iatrogenic blood loss and parent's complaints. The Pulse Co-oximetry (Masimo) is recently developed device which can provide noninvasive hemoglobin value. However, the accuracy is controversial. There are studies in pediatric patients during surgery and in ICU. However, the comparison for preoperative evaluation is not analysed. Therefore, the investigators want to evaluate the accuracy for preoperative preparation in pediatric patients.

There are not enough data comparing the noninvasive hemoglobin and venous hemoglobin in pediatric patients during preoperative period. The investigators will collect the venous sample and the noninvasive hemoglobin data from masimo within 1 hour. Without any additional medication, the patients will visit preanesthetic room and attach the probe of masimo on index finger. The R 20L or R25L will be used based on their weight. The parameter will be stabilized within 2 minutes and the SpHb and perfusion index will be recorded.

Inclusion Criteria:

• ASA class 1,2

Exclusion Criteria:

• Poor peripheral circulation
• Infection or trauma on the sensor contact region

pediatric patients age under 18 years planning to receive elective surgery under general anesthesia people live in South Korea