Equations to define as much as we can about the human body and its physiology. This list will be perpetually updated.

Haemodynamics

Systemic Vascular Resistance (SVR) – normal 700-1600 dyn.s.cm^-5
SVR = ([MAP-CVP] x 79.9) / CO

Systemic Vascular Resistance Index (SVRI) – normal 1900-2300 dyn.s.cm^-5.m^-2
SVRI = ([MAP-CVP] x 79.9) / CI

Cardiac Output (CO) – normal ~5L/min at rest
CO = HR x SV

Cardiac Index (CI) – normal 2.6-4.2 L/min/m²
CI = CO / BSI

Respiratory

Static lung compliance
[normal 50-100 mL/cmH₂O]
C_stat = V_tidal / (P_plat – PEEP)

Peak pressure
P_peak = P_airway + P_alveolar

Transpulmonary Pressure
[Ideal TPP 0-10 at end-expiration]
TPP = P_plat – P_oes

Body Metrics

Ideal Body Weight
– MALE = 50 + 0.91[height(cm) – 152.4]
– FEMALE = 45.5 + 0.91[height(cm) – 152.4]