Respiratory Equations Flashcards
Cardiac Output (CO)
CO = HR*SV = L/min
SV/1000 = L/min
Stroke Volume (SV)
SV = CO/HR
Units: mL/beat
CO*1000 = mL
Cardiac Index (CI)
CI = CO/BSA
Units: %
Oxygen Delivery (DO2)
DO2 = (CaO2*CO)10
Units: mL/min
Mean Arterial Pressure (MAP)
MAP = SBP + 2(DBP)/3
Units: mmHg
Alveolar Oxygen Tension (PAO2)
PAO2 = (Pb-PH2O)FiO2 - (PaCO2*1.25)
Units: mmHg
Barometric Pressure Pb(norm): 760
Water Vapor PH20 (Constant): 47
Alveolar-Arterial Oxygen Tension Gradient (PAaO2)
PAaO2 = PAO2-PaO2
Units: mmHg
Arterial Oxygen Content (CaO2)
CaO2 = (Hb1.34SaO2) + (PaO2*.003)
Units: mL/dL
Mixed Venous Oxygen Content (CvO2)
CvO2 = (Hb1.34SvO2) + (PvO2*.003)
Units: mL/dL
Arterial-Mixed Venous Oxygen Content Gradient (Ca-vO2)
Ca-vO2 = CaO2-CvO2
Units: mL/dL
End-Capillary Oxygen Content (CcO2)
CcO2 = (Hb1.34) + (PAO2.003)
Units: mL/dL
Oxygen Extraction Ratio (O2ER)
O2ER = CaO2-CvO2/CaO2
Units: %
Pulmonary Vascular Resistance (PVR)
PVR = (MPAP-PCWP)80/CO
Units: Dynes/Sec/cm^5
PVR = (MPA - PCWP)80/CO
Systemic Vascular Resistance (SVR)
SVR = (MAP-CVP)80/CO
Units: Dynes/Sec/cm^5
SVR = (MAP-RAP)80/CO
Deadspace-to-Tidal Volume Ratio (VD/Vt)
VD/Vt = (PaCO2-PeCO2/PaCO2)*100
Units: %
Shunt Equation (Qs/Qt)
Qs/Qt = CcO2-CaO2/CcO2-CvO2
Units: Vol%
Minute Volume (VE)
VE = f*Vt
Units: L/min
Tidal Volume (Vt)
Vt = VE/f
Units: mL/breath
Rapid Shallow Breathing Index (RSBI)
RSBI = RR/Vt
Units: Breaths/Min/L (BPM/L)
Static Compliance (Cs)
Cs = Vt/Plat-PEEP
Units: mL/cmH2O
Dynamic Compliance (Cd)
Cd = Vt/PIP-PEEP
Units: mL/cmH2O
Resistance Airway (RAW)
RAW = PIP-Pplat/Flow
Units: L/sec
Will need to convert Flow from L/min to L/sec
Calculate needed RR to get desired PaCO2
Desired RR (f) = Known PaCO2 x Known RR (f)/Desired PaCO2
Units: Breaths/min
Calculate needed VE to get desired PaCO2
Desired VE = Known PaCO2 x Known VE/Desired PaCO2
Units: L/min
