Shock: Recognition & First Moves

• Shock means the circulation fails to deliver enough oxygen; sort it at the bedside into cold & wet (cardiogenic), cold & dry (hypovolemic), warm & bounding (distributive), or obstructive (tamponade/PE/PTX).
• Hypoperfusion shows up as MAP <65, lactate >2, urine output <0.5 mL/kg/h, confusion, mottled skin, and capillary refill >3 s.
• Combining echo, IVC, and lung ultrasound at the bedside types the shock within minutes and alters treatment in ~1/3 of patients.
• Fix the underlying cause while holding up the pressure; noradrenaline is the default vasopressor.
• Resuscitation targets now include capillary refill normalization (ANDROMEDA-SHOCK-2) alongside MAP ≥65 and lactate clearance; assess fluid responsiveness with POCUS/PLR before each bolus.

Principal Etiologies of Shock

• Shock presentation: SBP <90 mm Hg · MAP <65 mm Hg · lactate ≥4 mmol/L
• Cardiac output low? CI <2.2 L/min/m² (thermodilution, or aortic flow assessment by transthoracic/esophageal Doppler)
• Shock — cardiogenic
• Narrow pulse pressure · low diastolic · cool extremities · sluggish nailbed refill · JVP ↑ · crepitations on lung exam +++ · S₃/S₄ gallop +++ · CXR: cardiomegaly with pulmonary edema · echo: reduced contractility and ejection fraction
• Shock — hypovolemic
• Narrow pulse pressure · low diastolic · cool extremities · sluggish nailbed refill · JVP ↓ · no crepitations or gallop · CXR: small cardiac silhouette · echo: obliteration of ventricular chambers
• Shock — septic
• Wide pulse pressure · diastolic ↓↓↓ · extremities warm/cool · brisk nailbed refill · JVP ↓ · CXR normal unless pneumonia present · infection site identified +++ · echo: hyperdynamic function

Less Common Etiologies of Shock

• Measure cardiac output via thermodilution, or aortic flow assessment by transthoracic or esophageal Doppler
• Cardiac output measured?
• Elevated cardiac output: CI >3.5–4.0 L/min/m²
• Think of: Paget's disease · thyroid storm · arteriovenous malformation
• Cardiac output low-normal: CI 2.2–3.5 L/min/m²
• Right atrial pressure & fluid responsiveness?
• Right atrial pressure high, fluid responsive
• Think of: pulmonary embolism · cardiac tamponade · right ventricular infarction
• Right atrial pressure low-normal, fluid unresponsive
• Think of: spinal shock · anaphylaxis · adrenal insufficiency