Assess Severity

• Is the degree of hypotension SERIOUS?
20% or more below baseline levels
If YES then validate reading (if possible)
• Associated with end-organ ischaemia
Drowsiness / Confusion / Agitation
Nausea
Angina / ST segment change
If YES then proceed to critical management


Otherwise Manage as for Mild to Moderate Hypotension

Hypotension Validation

• Check NIBP monitor - repeat cycle, check cuff size, check manually
• Confirm with palpation of large artery for pulse
If no pulse, manage as for CARDIAC ARREST
• Check Arterial line
Flush
Open to air and quickly confirm zero
Pulsatile waveform
• Independent pulse source - SpO2
• Has ET CO2 level fallen?
Low ETCO2 = Low Cardiac Output or Embolism

Critical Management 1

• 1. Increase Inspired OXYGEN
• 2. Is the hypotension EXPECTED?
Is it the result of an anticipated surgical intervention ?
If YES then manage in context of surgical causes
• If UNEXPECTED, quickly check that there are no obvious surgical issues e.g.
Sudden massive blood loss
IVC compression (including obstetrics / laparoscopy)
Femoral shaft reaming etc.
CO2 insufflation
Tourniquet or Vascular Clamp release

Critical Management 2 - Check ECG

• If Asystole / VF or pulseless VT then manage CARDIAC ARREST
• If TACHYARRHYTHMIA (AF/SVT/VT) then
Control rate with Vagal Manouvres / Vagotonic Drugs or Synchronized Cardioversion
Review possible causes including LIGHT ANAESTHESIA
• If SEVERE BRADYCARDIA then
Increase rate with Vagolytic agents (atropine)
Use chronotropic pressors (ephedrine, adrenaline)
Review possible causes including HYPOXIA

Critical Management 3 - Provide circulatory support in presence of normal rhythm

• 1. Volume resuscitation
First priority in context of recent neuraxial block
IV fluids
Posture legs up (if practical)
Consider wide-bore access
• 2. Vasopressors
Especially if GA or unresponsive to volume or limited ability to rapidly infuse fluids
Ephedrine / Metaraminol / Phenylephrine / Noradrenaline / Adrenaline / Vasopressin

Critical Management 4 - Assess CAUSE and provide SPECIFIC treatment

• Consider likely causes of SEVERE HYPOTENSION
Sudden BLOOD LOSS (surgical)
Impaired VENOUS RETURN (surgery / posture / high airway pressures / pneumothorax)
VASODILATION (neuraxial block - assess block height, anaesthetic agents, drug reactions including ANAPHYLAXIS)
EMBOLISM (Air / CO2 / orthopaedic / venous thromboembolism)
CARDIAC DYSRHYTHMIA
CARDIAC Dysfunction
Ischaemia / Infarction
Depressants (anaesthetic agents etc)

Critical Management 5 - Continue to Support Blood Pressure

• If still severely hypotensive
Call for assistance
Review Likely Causes
• If cause still not determined : Perform Systematic Review of
AIRWAY
• Pressures
• Minute Volume
BREATHING
• CO2 exchange
• Oxygenation
CIRCULATION
• Rhythm
• Ischaemia
• Volume (insert CVC / PAC / TOE)
DRUGS
• Check doses
• agents
• Consider other RARE CAUSES

Non-critical Management 1

• Validate reading
• Attempt to IDENTIFY CAUSE
• Treat by
CORRECTING CAUSE
DECREASING ANAESTHETIC DEPTH (if GA)
VOLUME (IV or posture)
VASOPRESSORS (if unresponsive to other measures)

Non-critical Management 2

• Relative HYPOVOLAEMIA
Neuraxial BLOCK (assess block height), inadequate fluid replacement
• Excessive relative DEPTH of ANAESTHESIA
Volatile agent / IV agent too high
• High AIRWAY PRESSURES
• SURGICAL
Blood Loss
Venous Return Compression
Release of tourniquet or vascular clamp
• Mild RHYTHM disturbance
Nodal rhythm, slow AF

Non-critical Management 3

• Perform Systematic Review of
AIRWAY
• Pressures / Minute Volume
BREATHING
• CO2 exchange
• Oxygentaion
CIRCULATION
• Rhythm
• Ischaemia
• Volume (insert CVC / PAC / TOE)
DRUGS
• Check doses
• agents
• Consider RARE CAUSES

Rare Causes of Intraoperative Hypotension

• Anaphylaxis
• Drug Error
• Transfusion Incompatibility
• Acute Mitral Valve Rupture
• Pericardial Tamponade
• Septic Shock
• Adrenocortical Insufficiency

N.B. In the intubated patient with refractory hypotension, TOE can provide useful information regarding myocardial function and filling status