Module 01
Hemodynamics
Feel the math behind the monitor. Drag the sliders, watch the physiology move.
Live Physiology
Strong squeeze
Chambers stretch with preload, squeeze with contractility, eject against SVR.
ART · 116/66
80 bpm
PV Loop
SV 32 mL · EF 22%
Compensation Reserve
Status
Compensated
MAP
86
mmHg
CO
4.3
L/min
SVR
900
dyn·s
DO₂
860
mL/min
Preload (tank volume)Optimal
SVR (pipe tension)Normal
Contractility (squeeze)Normal
Heart rate80 bpm
◆ Memory Aid
Tank · Pipes · Pump. Preload is what's in the tank. SVR is how tight the pipes are. Contractility is how hard the pump squeezes. Lose any one and MAP drops.
Core Concepts
Shock Models
Septic Shock
"Floppy pipes — the pump is fine, the tubing is wide open."
Preload
Low
Afterload
Low
Contract
Normal
SVR
Low
CO
High
PP
Wide
Bedside
- Warm, flushed extremities (early)
- Bounding pulses
- Fever or hypothermia
- Altered mental status
Ultrasound
- Hyperdynamic LV (kissing walls)
- Small, collapsing IVC
- Normal RV
Lactate · Elevated from microcirculatory failure and adrenergic glycolysis — not always pure hypoperfusion.
Pulse Pressure · Wide — diastolic collapses while systolic holds.
Treatment Priorities
- Early norepinephrine (don't wait)
- Targeted fluids guided by responsiveness
- Add vasopressin at 0.03 U/min if norepi climbing
- Source control + antibiotics within 1h
Common Mistakes
- Drowning the patient in fluids past responsiveness
- Withholding norepinephrine to 'try fluids first'
- Chasing MAP with phenylephrine
✕ Myth
A normal MAP means the patient is being perfused.
✓ Reality
MAP is one variable. Lactate, mottling, mentation, and UOP tell you whether tissues are actually getting oxygen.