Formulas Flashcards
Minute Ventilation (VE)
VE = Respiratory Rate × Tidal Volume
Alveolar Minute Ventilation (VA)
VA = (Tidal Volume – Deadspace) × Respiratory Rate
Airway Resistance (Raw)
Raw = (PIP – Plateau Pressure) ÷ Flow
Mean Airway Pressure (Paw)
Paw = ((Inspiratory Time × Frequency) ÷ 60) × (PIP – PEEP) + PEEP
A-a Gradient
P(A-a)O2 = PAO2 – PaO2
Alveolar Air Equation
PAO2 = (PB – PH2O) × FiO2 – (PaCO2 ÷ 0.8)
a/A Ratio
(a/A) Ratio = PaO2 ÷ PAO2
Arterial Oxygen Content (CaO2)
CaO2 = (Hb × 1.34 × SaO2) + (PaO2 × 0.003)
End-Capillary Oxygen Content (CcO2)
CcO2 = (Hb × 1.34 × SaO2) + (PAO2 × 0.003)
Mixed Venous Oxygen Content (CvO2)
CvO2 = (Hb × 1.34 × SvO2) + (PvO2 × 0.003)
Anatomical Shunt
QS/QT = (CcO2 – CaO2) ÷ (CcO2 – CvO2)
Arterial-Mixed Venous Oxygen Content Difference (C(a-v)O2)
C(a-v)O2 = CaO2 – CvO2
P/F Ratio
PaO2 ÷ FiO2
Oxygenation Index (OI)
OI = ((Paw × FiO2) ÷ PaO2) × 100
Oxygen Consumption (VO2)
VO2 = Cardiac Output × C(a-v)O2
FiO2 Estimation for Nasal Cannula
FiO2 = 20 + (4 × Liter Flow)
Oxygen Cylinder Duration
Duration = (Gauge Pressure × Tank Factor) ÷ Liter Flow
Cardiac Index (CI)
CI = Cardiac Output ÷ Body Surface Area
Cardiac Output (CO)
CO = Heart Rate × Stroke Volume
Cerebral Perfusion Pressure (CPP)
CPP = Mean Arterial Pressure – Intracranial Pressure
Mean Arterial Pressure (MAP)
MAP = (Systolic BP + (2 × Diastolic BP)) ÷ 3
Stroke Volume (SV)
SV = Cardiac Output ÷ Heart Rate
Respiratory Quotient (RQ)
RQ = VCO2 ÷ VO2
Systemic Vascular Resistance (SVR)
SVR = (MAP – CVP) × (80 ÷ Cardiac Output)
