Hemodynamics, Perfusion, and Shock Management
Perfusion is the endpoint, not the number
Shock is oxygen delivery that is inadequate for demand. The transport clinician must classify it quickly: hypovolemic/hemorrhagic, cardiogenic, distributive (septic, neurogenic, anaphylactic), and obstructive (tension pneumothorax, tamponade, massive pulmonary embolism). Each has a different first move, so mechanism and exam beat any single pressure reading.
Key concepts: MAP, roughly (SBP + 2×DBP)/3, with a usual target of at least 65 mmHg; pulse pressure as a stroke-volume clue; capillary refill, mentation, urine output, and lactate clearance as perfusion markers. Know preload, afterload, and contractility well enough to predict what a fluid bolus, a vasopressor, or a PEEP change will do. Know your vasopressor concentration and the principle that a running infusion should not be interrupted for transport without a plan - a second pump, adequate drug supply, or a deliberate bridge.
Trap: neurogenic shock presents with hypotension and bradycardia rather than tachycardia. Another: a normal blood pressure with a narrow pulse pressure in a young trauma patient is compensated shock, not reassurance.
Worked example: hypotensive, clear lungs, warm extremities, known sepsis. Rule of thumb: warm vasodilated shock responds to volume first, then norepinephrine; cold, mottled, cardiogenic-appearing shock gets cautious fluid and inotropic support. Reassess and document after every 250-500 mL.
Also remember that cabin altitude reduces available oxygen for a patient already at the edge of reserve - a 90% saturation on the ground can fall at altitude.