Shock: a bedside approach by type

What it is

Shock is acute circulatory failure in which the delivery of oxygen to the tissues does not meet their demand, so cells switch to anaerobic metabolism, lactate rises and organs begin to fail. Low blood pressure is common but not required: a patient can be in shock with a normal pressure, especially early or when chronically hypertensive. Four mechanisms are described. Hypovolaemic shock follows loss of blood or fluid; cardiogenic shock follows failure of the heart as a pump; obstructive shock follows a block to filling or outflow, such as tension pneumothorax, cardiac tamponade or massive pulmonary embolism; and distributive shock follows loss of vascular tone, as in sepsis, anaphylaxis, spinal cord injury or adrenal crisis. Patients often have more than one mechanism at once. The bedside approach combines a quick look at perfusion (mental state, skin, capillary refill, urine output), a few targeted signs (jugular veins, lungs, heart sounds, temperature of the hands), lactate and point-of-care ultrasound of the heart, lungs, inferior vena cava and abdomen. Treatment starts at the same time as the search: oxygen, venous access, fluids when the patient is likely to respond, a vasopressor for persisting hypotension aiming at a mean arterial pressure around 65 mmHg, and control of the cause, which is what finally reverses shock.

What to assess

• Perfusion: confusion or drowsiness, mottled or cold skin, capillary refill slower than about three seconds, falling urine output.
• Pressure and rate: mean arterial pressure, heart rate and the shock index (heart rate divided by systolic pressure; above one is worrying).
• Filling clues: jugular venous pressure, crackles, a third heart sound, muffled heart sounds or absent breath sounds on one side.
• Context: bleeding, vomiting or diarrhoea, chest pain, infection source, recent drug or allergen, spinal injury, steroid use.
• Lactate and blood gas: a raised lactate and base deficit show hypoperfusion and give a trend to follow.
• Point-of-care ultrasound: heart size and squeeze, pericardial fluid, right ventricle size, lung sliding and B-lines, inferior vena cava, free fluid.

How it is done (and why)

1. Call for help and start ABCDE with oxygen and monitoring — shock worsens fast and needs several people at once.
2. Place two large-bore cannulas and send gas, lactate, blood count, crossmatch, cultures and troponin — access and baseline come before the next decision.
3. Look at skin temperature, jugular veins, lungs and heart sounds — these quickly separate cold-and-full from warm-and-empty patterns.
4. Scan with ultrasound: heart, pericardium, lungs, vena cava and abdomen — it finds tamponade, a dilated right ventricle, pneumothorax and bleeding.
5. Give a fluid challenge if the patient is likely to respond, and reassess after each one — fluids help the empty circulation and harm the congested one.
6. Start a vasopressor if hypotension persists, peripherally at first if needed — prolonged low pressure injures brain, heart and kidneys.
7. Treat the cause: stop bleeding, give antibiotics and source control, decompress, drain or reperfuse — only removing the cause reverses shock.
8. Place an arterial line and catheterise the bladder when shock persists — beat-to-beat pressure and hourly urine output guide titration.

The four types of shock at the bedside

Findings that change the plan

• Tension pneumothorax, tamponade or massive pulmonary embolism: decompress, drain or reperfuse at once; delay is fatal.
• Cardiogenic shock: be cautious with fluids, consider an inotrope and urgent coronary reperfusion when an infarction is the cause.
• Anaphylaxis: adrenaline first, then fluids; neurogenic shock: slow heart rate with warm limbs after spinal injury.
• Refractory shock in a patient on long-term steroids or with sepsis: think of adrenal insufficiency and give stress-dose corticosteroid.
• Rising lactate or worsening organ function despite treatment: look again for an uncontrolled source or a second mechanism.

Next step

• Repeat lactate every few hours and follow urine output, mental state and capillary refill as signs of recovery.
• Call the senior intensivist early when a vasopressor is needed, lactate does not clear or the cause is unclear.
• Move to intensive care for an arterial line, a central line if pressors continue and closer monitoring.
• Once stable, reassess fluid balance daily and remove excess fluid; plan the step-down from vasopressors.
• Document the type of shock, the cause found and the response to each intervention for the handover.

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Elsewhere in DurgiPedia

• Shock physiology
• Oxygen content, delivery and extraction
• Shock: types, stages and the organs it damages
• Shock: the clinical signs and the types
• Capillary refill time
• Fever, infection and sepsis: the bedside signs

Connections

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Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.

Sources: Shock (StatPearls (NCBI Bookshelf), 2023); Shock Resuscitation (StatPearls (NCBI Bookshelf), 2023).

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