K2i: The PD effects of propofol & how this influences its clinical usage

  • Propofol = 2,6 di-isopropyl-phenol
Propofol

Property

Clinical Usage

Dose dependent effects

Sedation, anxiolysis, GA (induction, maintenance)

MoA

  • ↓ rate of GABA dissociation from GABA receptors
  • ↑duration of Cl– channel operating → cell membrane hyperpolarisation. Inhibits NMDA receptor by channel gation modulation (inhibits currents activated by NMDA)

Induction: 2mg/kg

Maintenance: 0.2mg/kg/min

Levels (mcg/mL)

  • 3 = psychomotor effects
  • 0 = sleep
  • 4.0 = major surgery

CNS

  • Rapid LOC
  • Rapid emergence
  • Amnesia
  • No analgesia
  • ↓CBF/↓CPP/↓CBF
  • Useful for RSI
  • Day surgery/short cases/neurosurg for quick new assessment/TIVA
  • ↓adverse experience
  • Needs opioid
  • Suitable for neurosurg cases or HI/risk of space-occ lesions

CVS

  • Local release NO → ↓↓SVR
  • Negative inotrope

↓MAP monitoring required

Patient needs to be well filled

Caution in shocked states/bypassed/HF

Beneficial for patients with IHD

Resp

  • Dose-dependent resp depression
  • Impairs response to ↑PaCO2/↓PaO2
  • Inhibits laryngeal reflex
  • Bronchodilation
  • Requires professionals skilled in airway management
  • SpO2 monitor required
  • Suitable for LMA insertion/airway instrumentation
  • Suitable for asthmatics

GI

  • Anti-emetic (?O2 antagonist)
  • N&V refractory
  • Suitable for patient @ high risk PONV

Other

  • Pain on injection
  • Does not cause MH

↓

  • ↓intra-ocular P
  • Requires lignocaine
  • Suitable for patients as an alt. to inhalationals
  • Suitable for eye surgery

TOXICITY

Propofol infusion syndrome

  • Hepatic failure, rhabdo, severe metabolic acidosis, renal failure
    • Minimise dose/infusion
    • Rare fatal
    • Critical children with Long T propofol infusion @ high doses