Difference between revisions of "Estimating VO2"
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* You can calculate the V̇O2 using the Fick equation: <math chem>\ce{\dot VO2} = Q \times\ (C_a\ce{O2} - C_v\ce{O2})</math>, where Q is the cardiac output. | * You can calculate the V̇O2 using the Fick equation: <math chem>\ce{\dot VO2} = Q \times\ (C_a\ce{O2} - C_v\ce{O2})</math>, where Q is the cardiac output. | ||
* [https://en.wikipedia.org/wiki/VO2_max#Reference_values Reference values] for V̇O2 max | * [https://en.wikipedia.org/wiki/VO2_max#Reference_values Reference values] for V̇O2 max | ||
| − | * In 2016, the | + | * In 2016, the AHA published a scientific statement recommending that CRF {{ndash}} quantifiable as V̇O<sub>2</sub> max/peak {{ndash}} be regularly assessed and used as a clinical vital sign; ergometry (exercise wattage measurement) may be used if V̇O<sub>2</sub> is unavailable.<ref name="ross">{{cite journal |last1=Ross |first1=Robert |last2=Blair |first2=Steven N. |last3=Arena |first3=Ross |last4=Church |first4=Timothy S. |last5=Després |first5=Jean-Pierre |last6=Franklin |first6=Barry A. |last7=Haskell |first7=William L. |last8=Kaminsky |first8=Leonard A. |last9=Levine |first9=Benjamin D. |last10=Lavie |first10=Carl J. |last11=Myers |first11=Jonathan |last12=Niebauer |first12=Josef |last13=Sallis |first13=Robert |last14=Sawada |first14=Susumu S. |last15=Sui |first15=Xuemei |last16=Wisløff |first16=Ulrik|display-authors=3 |title=Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association |journal=Circulation |date=13 December 2016 |volume=134 |issue=24 |pages=e653–e699 |doi=10.1161/CIR.0000000000000461 |pmid=27881567 |s2cid=3372949 |doi-access=free }}</ref> |
Revision as of 23:34, 9 August 2024
- An automated machine check could calculate the amount of machine leak you have in the circuit, separate from any patient leak. Just occlude the Y-piece and run the vent while comparing your VTI - VTE. Average 20 breaths or so and likely there is a delta of a few ml with each breath accounting for air lost from circuit connections, internal machine leaks, tubing, etc. Variability may also be due to measurement error from the flow meters used.
- Once connected to the patient, VTI - VTE gives the total volume lost per breath. Subtract the machine leak found above and this gives you the patient side leaks (air lost from around the ETT cuff, volume lost to chest tubes, etc)
- FiO2 * FGF = V̇O2
- You can calculate the V̇O2 using the Fick equation: <math chem>\ce{\dot VO2} = Q \times\ (C_a\ce{O2} - C_v\ce{O2})</math>, where Q is the cardiac output.
- Reference values for V̇O2 max
- In 2016, the AHA published a scientific statement recommending that CRF Template:Ndash quantifiable as V̇O2 max/peak Template:Ndash be regularly assessed and used as a clinical vital sign; ergometry (exercise wattage measurement) may be used if V̇O2 is unavailable.[1]