Anaesthetics Flashcards
What effect does GA have on CV + Resp systems?
CV:
Reduced contractility (CO/Hypotension)
Arrhythmia
Resp:
Resp depression
Reduced ventilator response to hypoxia/hypercapnia
Laryngospasm
What should be included in pre-op assessment in:
Pre-existing CV disease
Pre-existing resp
CV: Risk peri-op MI
• ECG ± ECHO
Resp: Higher risk post-op comps
• ABG
• CXR
• Pulm function
What are the common/major risks assoc w. GA (5)
PONV (post-op N+V) Awareness under GA Anaphylaxis Cardio-resp issues Aspiration
What are the common/major risks assoc w. Spinal (6)
PONV (if opiates used) Cardio-resp issues Neurological damage Spinal headaches High spinal block (brainstem depression) Urinary retention
Outline the WHO pain ladder
- Non-opioid ± adjuvant (e.g. para ± NSAID)
- Weak opioid ± non-opioid ± adjuvant
- Strong opioid ± non-opioid ± adjuvant
What factors allow for a reduced dose of paracetamol? (4)
<50kg
Old age
Alcoholism
Poor nutrition
List the COX-1 SEs (6)
Dyspepsia/ulceration Bronchospasm Reduced platelets Cardiotoxicity Nephrotoxicity Skin reactions
List absolute CIs (2) to NSAIDs
List relative CIs/Cautions with NSAIDs (3)
Absolute:
Severe HF
H/o GI bleed / ulceration
Relative:
Elderly
Asthma
Coagulopathy
What are COX-2 selective inhibitors used?
+ main ADR
e.g. celecoxib
For RA/OA
Esp if thrombocytopenia / UGI complications
Main ADR: risk serious cardiac event
What are the absolute CIs to opiate use (4)
Acute resp deo
Acute alcoholism
Raised ICP
Risk paralytic ileus
What is the management of opiate overdose
Pts >12:
- 400micrograms IV naloxone
- No response 1min – 800mcg
- No response 2mins – 800mcg
If severely poisoned: 2mg/4mg doses
What is the triad of GA?
Relaxtion
Analgesia
Narcosis
What are the advantages of TIVA? (total IV anaesthetic)
if PMH/FH malignant hyperthermia
to reduce PONV
for more control over depth of analgesia
What inhalation agents are available? (4) + which 2 are the ones mainly used
Halothane
Isoflurane
Sevoflurane*
Desflurane*
Why is halothane not used anymore?
Complication of hepatitis
Advantages of sevo/desflurane?
Sevo: combo of low irritant + fast onset-offset
Des: rapid onset
Low absorption into fat (used in morbidly obese)
However more of a resp irritant
What IV anaesthetic agents are available? (4)
Propofol
Thiopental sodium
Etomidate
Ketamine
Uses of Propofol (3)
Usual doses
Uses:
•Induction/maintenance of GA
•Sedation (regionals / short procedures)
•Sedation in ITU
Usual doses:
Induction: 2mg/kg IV at 2-4mg/sec
Maintenance: 4-12mg/kg/hr
CIs of Propofol (3)
Problems with Propofol (1)
CI:
• Extremes of age (<17 + elderly)
• Egg/soy allergy
• Compromised airway
Problems:
• Pain on injection (40%)
Uses of thiopental (2)
Problems with thiopental (not CIs)
GD induction Potent anticonvulsant (one of last resort in status epilepticus)
–ve inotrope; CO drops by 20%
Poss bronchoconstriction
Advantages of propofol over other IV agents?
Smooth induction
Stable haemodynamic parameters
Rapid recovery
CIs if thiopental (6)
Airway obstrn
Compromised airway
Hypovol / low BP
Fixed CO states (e.g. mitral stenosis)
Barbiturate allergy
Porphyria
Advantages/uses of etomidate
Problems with etomidate
Safe CV profile Easy dosing (0.15-0.3mg/kg) Non-apnoeic No histamine release THEREFORE protects from myocard/cerebral ischaemia Good for trauma/head injury pts
Probs: Invol mm movements Nausea Adrenal supp Local thrombophlebitis
Advantages / problems with Ketamine
No change to CO (good analgesia w/o compounding shock)
Probs: Slow recovery Emergence delirium Maintenance of laryngeal reflexes Avoid in HTN/Stroke/Raised ICP
