Systems and methods for measuring mitochondrial capacity
In one embodiment, measuring mitochondrial capacity includes performing arterial occlusions on a patient, measuring oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin within the patient's body during the occlusions, calculating a blood volume correction factor that accounts for a change in blood volume that occurs during the arterial occlusions, and applying the correction factor to the measured oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measurements to obtain correct oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measurements.
1. A system for measuring mitochondrial capacity, the system comprising:
a near-infrared spectroscopy device adapted to measure oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin of a patient during arterial occlusions; and
a computing device in communication with the near-infrared spectroscopy device that comprises a processor and memory for determining mitochondrial capacity, the memory comprising instructions stored thereon that when executed by the processor perform the steps of:
receive measurements of the oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measured by the near-infrared spectroscopy device,
calculating a blood volume correction factor that accounts for a change in blood volume that occurs during the arterial occlusions, and
apply the correction factor to the oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measurements to obtain corrected measurements, and calculating oxygen consumption using the corrected measurements.
2. The system of claim 1 , wherein calculating a blood volume correction factor comprises calculating a correction factor that adjusts the oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measurements so that a decrease in the oxygenated hemoglobin/myoglobin measurement is equivalent to an increase in the deoxygenated hemoglobin/myoglobin measurement.
3. The system of claim 1 , wherein calculating a blood volume correction factor comprises calculating the factor using the following equation:
β
i
=
O
2
Hb
i
(
O
2
Hb
i
+
HHb
i
)
where β is the blood volume correction factor, O 2 Hb is the oxygenated hemoglobin/myoglobin measurement, and HHb is the deoxygenated hemoglobin/myoglobin measurement.
4. The system of claim 3 , wherein applying the correction factor comprises calculating corrected oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measurements using the following equations:
O 2 Hb c = O 2 Hb −[ tHb *(1−β)]
HHb c = HHb −( tHb *β)
where O 2 Hb c , is the corrected oxygenated measurement, HHb c , is the corrected deoxygenated hemoglobin/myoglobin measurement, and tHb is the arithmetic sum of the O 2 Hb and HHb.
5. The system of claim 1 , wherein calculating a blood volume correction factor comprises calculating a global correction factor that will be applied to all measurements.
6. The system of claim 1 , wherein calculating a blood volume correction factor comprises calculating separate correction factors that will be individually applied to the measurements for each occlusion.
7. The system of claim 1 , wherein calculating a blood volume correction factor comprises iteratively searching for a blood volume correction factor that results in the smallest error for the difference between the oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measurements.