cardiovascular Emergencies

Aetiology of Perioperative Hypertension

Sympathetic response
Pre-existing hypertension
Hypoxaemia/hypercarbia
Drug effects
Cerebral ischaemia
Preload (Volume overload)
Afterload

Sympathetic response

“Light” anaesthesia
Painful stimulus
Emergence
Bladder distention
Tourniquet

Pre-existing hypertension

Essential hypertension
Renovascular
Pre-eclampsia
Autonomic dysreflexia
Other endocrine-e.g. phaeo, hyperthyroid
Drugs

Drug Effects

Vasopressors
Withdrawl E.g.

Clonidine

Beta blockers.

Methyldopa.

Interactions-e.g.MAOIs.

With pethidine

Metaraminol

Ephedrine

Cocaine

Cerebral Ischaemia

Raised ICP
Carotid/Vertebral occlusion, e.g. from neck positioning

High Afterload

Aortic crossclamp
Pneumoperitoneum
Hypothermia

Basic Management Flowchart

Exclude artefact.
Assess severity.
Assess aetiology.
Select treatment.

Exclude Artefact

NIBP
Repeat measurement

Check system, verify correct cuff & application

Measure manually

Intra-arterial

Check transducer position and zeroing

>Check system. Flush line

Confirm with NIBP (manual or automatic)

Assess Severity

Mean BP >120mmhg or > 30% above baseline
ST depression present
Patient Factors

E.g. known ischaemic heart disease

Cerebrovascular disease

Aneurysm
Associated bleeding

Any of above = severe
Urgent treatment required.

Assess Aetiology

Assess anaesthetic depth
Check anaesthetic delivery
Check vasoactive drug administration
Check ventilation and oxygenation
Consider surgical factors

Anaesthetic Depth

Is the depth appropriate for the level of stimulus?
Check:

Respiratory effort/rate & patient movement.

Tachycardia.

Sweating & tearing.

>Eye signs.

BIS may be useful if available.

Anaesthetic Delivery

Inhalational agents:

Confirm end tidal anaesthetic level

Check fresh gas flow

Check vaporiser:

Correct setting
Correct seating, locked & leak free
Adequately filled

Anaesthetic Delivery

Intravenous anaesthesia

Visually check infusion of anaesthetic and carrier fluid, including I.V. site

Check infusion rate and proper running of infusion

Recheck dosage/concentration calculations

Consider converting to or adding volatile agents (whose end tidal concentration can be confirmed)

B.I.S. may be useful if available

Drug administration

Vasoactive agents:

Check infusion rate and dosage calculations

Confirm that the correct drug is being used

Are there other drugs being used?

E.g. adrenaline containing local anaesthetic

Desflurane

Ventilation and Oxygenation

SpO2 and EtCO2.
Clinically assess ventilation and airway
ABG’s if problems suspected

Surgical Factors

Anticipate high levels of surgical stimulation and increase depth accordingly
Remember other factors such as:

Tourniquet, pneumoperitoneum, cross clamp

Treatment for isolated Hypertension

Vasodilators
Alpha-blockers
Beta blockers

Especially if associated with tachycardia

Beware contraindications

Dilators

Hydralazine:

5-10 mg I.V. repeat every 20’

GTN:

15mg in 25 mls = 600 mcg/ml

Start @ 20 mcg/min (2ml/hr) & titrate

Or 0.5-20 mcg/kg/min

Na Nitroprusside

Start @ 20 mcg/min & titrate

Or 0.5-8.0 mcg/kg/min

Alpha-blockers

Clonidine:

150mcg I.V. in divided doses

Phentolamine:

0.5-1mg increments

Beta Blockers

Atenolol

1-2mg I.V. up to 10 mg

Esmolol

5-10 mg increments

Or Infusion- 50-300 mcg/kg/min

Indicated with associated tachycardia, evidence of cardiac ischaemia, or known C.A.D
Consider contraindications:

Significant broncospasm

Suspected phaeochromocytoma

Raised I.C.P.

Mannitol

0.5-2 g/kg I.V.

Moderate hyperventilation

Down to arterial pCO2 30mmHg

Frusemide

5-10 mg I.V.

The aim is to preserve cerebral perfusion pressure
Followed by urgent neurosurgical intervention