Hypotension

Exam Cram

• Hypotension is defined as a blood pressure < 90/60 or MAP < 65

• Assessment of end organ perfusion is key to determine if the hypotension is significant- i.e. urine output (kidneys), confusion (brain) and lactate (muscular oxygenation)

• Hypotension aetiology: hypovolaemia (bleeding, diarrhoea), cardiogenic, neurogenic, immune (sepsis, anaphylaxis)

• Management depends upon cause and a fluid balance assessment is required to consider IV fluids or furosemide; consider stopping antihypertensives

Hypotension is commonly referred to as shock. 

Definitions

Blood pressure:

• Hypertension: > 140/90

• Normotensive: 120/80

• Hypotensive: < 90/60

In particular, some clinician just use the systolic, aiming for > 90.

Alternatively the mean arterial blood pressure (MAP) can be used, aiming > 65. 

Assessment

Key question: are we achieving end organ perfusion?

This is assessed by:

• Brain: Is the patient confused, suggesting hypoxic delirium?

• Kidneys: Urine output sufficient, creatinine & urea stable (Acute Kidney Injury (AKI) 

• Muscles: Receiving oxygenated blood for aerobic respiration, lactate can be a useful marker 

Assessment

If asked to see a patient with a blood pressure below 90/60, this is a medical emergency and requires an A-E response. 

1. Check true value- correct cuff, patient in a reasonable posture

2. GCS ?confusion/ delirium

3. Urine output- hourly via catheter can be helpful, aim > 0.5ml/kg/hr

4. Lactate

5. HR- if raised, can be a sign body isn't happy with the BP & vice versa

Causes

Acronym 'AH CIN', in order of most common

• Asymptomatic- vagal, common overnight for BP to naturally drop

• Hypovolaemia

  • Bleeding

  • Dehydration- sepsis, vomiting, diarrhoea

• Cardiogenic

• Immune related

  • Sepsis

  • Anaphylaxis

• Neurogenic

Management

Management of hypotension is dictated by underlying cause. 

1. Optimising Medical Ward Management

Asymptomatic: nil intervention required, can encourage positional changes/ PO fluids

Medications: 

• Consider suspending antihypertensives: ACE inhihitors, alpha & betablockers, thiazide duiretics & loop duiretics

• Note indication, e.g. caution stopping a betablocker for AF that could lead to fast AF

• If dehydrated stop diuretics, if overloaded these may need to be increased

Hypovolemia:

• Dehydration- IVF 250mls to 500mls bolus

• Bleeding- replace blood with blood +- IVF

Cardiogenic: 

• Furosemide 40mg IV if overloaded +- another 40mg 

• Fast AF: betablockers, digoxin or amidoarone

Immune

• Sepsis- IVF, requires total of 2L 

• Anaphylaxis- adrenaline

2. HDU/ ICU

Vasopressors

• Hypotension not responding to IVF or IV furosemide, requires vasopressors 

• Vasopressors require HDU/ ICU level care. 

Resources and References

Written in 2025