The purpose of this study is to evaluate the value of the new technique of non-invasive measurement of Hb in children undergoing a surgical procedure.

Several surgical procedures require haemoglobin monitoring due to possible blood loss and the need of blood transfusion. The standard for monitoring hemoglobin (Hb) is the measurement of blood samples. The novel technique of non-invasive continuous measurement of Hb using Pulse CO-Oximetry may allow measuring Hb without obtaining blood samples.

This new technique has not been tested yet in children undergoing anesthesia for elective surgical procedures. In this study the investigators compare the non-invasive Hb measurement with Masimo® technology (SpHb) with the standard Hb measurement using ABL-800 Flex (BGA) and Siemens Advia (labHb, reference method) before the children undergo the surgical procedure.

Inclusion Criteria:

• children (>= 3 kg until 8 years)
• ASA I-III
• written informed consent of legal representative

Exclusion Criteria:

• children <= 3kg or > 8 years
• emergency surgery
• allergy against sensor of SpHb(®)
• artery occlusive disease
• sepsis
• haemoglobinopathy
• specific medical or psychological circumstances which do not allow the consent of the legal representative or the performance of the study