* Masimo SpHb™ continuous hemoglobin monitoring The Masimo SpHb™ monitor with the Butterfly Sensor with RevK version will be used to continuously monitor hemoglobin electronically. The Butterfly Sensor will be connected to the 3rd or 4th finger on either the right or left hand.
* Masimo Pronto-7™ intermittent hemoglobin monitoring The Masimo Pronto-7™ is a hand-held, noninvasive device used for intermittent measuring of blood hemoglobin. The device is connected to a re-usable sensor which is clipped onto a finger for quick spot-check readings. A reading from the Pronto-7 will be taken immediately before surgery.
* Blood sampling for hemoglobin determination For the study, about a ½ tsp of blood will be collected from the arterial line placed for the purpose of surgery approximately every hour during the surgery to obtain a hemoglobin measurement to be analyzed in the UCSF Clinical Lab.