2013C02 What are the advantages and disadvantages of Xenon as an anaesthetic agent?

 

List:

·     Intro

·     PC

·     PK

·     PD

 

 

Pros

Cons

PC

·  No smell, non-irritant, gas induction ok

·  Stable, non-reactive with circuit, non-combustible

·  Expensive

·  Not yet recyclable

·  Gas at room temp; inefficient storage

·  High density -> ↑resistance to turbulent flow

·  High viscosity -> ↑resistance to laminar flow

PK

·  Low blood:gas partition coefficient (0.14): rapid onset, rapid offset

·  Rapid onset -> ↓risk laryngeal spasm etc

·  Short context-insensitive decrement times

·  Only mild diffusion hypoxia

·  No metabolism

·  Low potency limits FiO2 (MAC 71%, associated with oil-gas partition coefficient 1.9)

·  Very fast offset: spont vent + disconnection -> rapid ↓ partial pressure

PD

CNS:

·  Analgesia (NMDA antagonist)

·  Not emetogenic

·  ↑CBF -> luxury perfusion if normal brain

CVS:

·  Minimal ↓HR, ↔contractility, ↔SVR (Ca2+ channel antagonist)

·  No sensitization to catecholamines

·  No QTc prolongation

Resp:

·  (No smell, non-irritant-> gas induction ok)

·  Minimal ↓MV (note (↑TV, ↓RR)

·  Airway reflexes preserved – suitable for sedation with native airway

 

Immune: no suppression

 

MSK: doesn’t trigger malignant hyperthermia

CNS:

·  ↑CBF -> ±↑ICP if intracranial pathology

 

 

CVS:

·  No ischaemic preconditioning

 

 

Resp:

·  Airway reflexes preserved – unsuitable for gas only induction

·  High density and viscosity