Abstract: A hemoglobin measuring device comprising a controller, a first oxygen sensor, a second oxygen sensor, a first volume flow meter, and a second volume flow meter. The controller is operable to receive data from each of the first and second oxygen sensors, the first and second volume flow meters, and a pulse oximeter associated with a patient. The controller is also operable to determine a hemoglobin level of the patient, defined as a determined hemoglobin level, based on the data received from the first and second oxygen sensors, the first and second volume flow meters, and the pulse oximeter.