SU2.1-2 | Shock Pathophysiology and Resuscitation — Summary & Reflection

KEY TAKEAWAYS

Shock is inadequate tissue perfusion, and recognising it depends on the bedside signs — tachycardia, a narrowed pulse pressure, cool clammy oliguric peripheries and altered mentation — because hypotension is a LATE sign. The ATLS classes I–IV link blood loss (<15 / 15–30 / 30–40 / >40%) to escalating signs, with hypotension appearing only at Class III+. The four mechanistic types are hypovolaemic, cardiogenic, distributive (septic, anaphylactic, neurogenic) and obstructive (tension pneumothorax, tamponade, massive PE), each with a distinct preload/cardiac-output/SVR profile. Assessment is the ABCDE primary survey with monitoring by urine output (>0.5 mL/kg/h), lactate clearance and base deficit. Resuscitation = restore perfusion + treat the cause: crystalloid then blood for haemorrhage, balanced 1:1:1 massive transfusion, permissive hypotension in uncontrolled bleeding, damage-control resuscitation to avoid the lethal triad (hypothermia, acidosis, coagulopathy), and cause-specific therapy (decompress obstruction; IM adrenaline for anaphylaxis; cautious fluid + inotropes for cardiogenic; fluids + early antibiotics + vasopressors for septic).

REFLECT

Recall a deteriorating patient you have seen — in the trauma bay, on the ward after surgery, or in a simulation. Did you notice the early warning of a rising heart rate and narrowing pulse pressure, or did you wait for the blood pressure to fall before you acted? Now consider your mental algorithm: faced with a shocked patient, could you run the ABCDE survey, decide quickly which of the four types you are dealing with, and choose the right first move — blood and source control for haemorrhage, decompression for an obstructive cause, adrenaline for anaphylaxis, antibiotics and fluids for sepsis? Reflect on how committing the haemorrhagic-shock classes and the principle of permissive hypotension to memory now would change how confidently you start resuscitation before your senior arrives.