Airway management Flashcards
(38 cards)
Oropharyngeal airway - features
Easy to insert and use
No paralysis required
Ideal for very short procedures
Most often used as bridge to more definitive airway
Laryngeal mask features
Widely used
Very easy to insert
Device sits in pharynx and aligns to cover the airway
Poor control against reflux of gastric contents
Paralysis not usually required
Commonly used for wide range of anaesthetic uses, especially in day surgery
Not suitable for high pressure ventilation (small amount of PEEP often possible)
Tracheostomy features
Reduces the work of breathing (and dead space)
May be useful in slow weaning
Percutaneous tracheostomy widely used in ITU
Dries secretions, humidified air usually required
Endotracheal tube features
Provides optimal control of the airway once cuff inflated
May be used for long or short term ventilation
Errors in insertion may result in oesophageal intubation (therefore end tidal CO2 usually measured)
Paralysis often required
Higher ventilation pressures can be used
ASA I definition and example
Normal healthy patient
Healthy, non-smoker, no or minimal alcohol use
ASA II definition and example
A patient with mild systemic disease
Mild diseases only without substantive functional limitations. Examples include (but not limited to): current smoker, social alcohol drinker, pregnancy, obesity (BMI 30 - 40), well-controlled Diabetes Mellitus/Hypertension, mild lung disease
ASA III definition and example
A patient with severe systemic disease
Substantive function limitations. One or more moderate to severe diseases.
Poorly controlled Diabetes mellitus/ hypertension, COPD, morbid obesity (DMI >40), active hepatitis, alcohol dependence or abuse.
Implanted pacemaker
ASA IV definition and example
Patient with severe systemic disease - constant threat to life
recent (< 3 months) of Myocardial infarction, Cerebrovascular accidents, ongoing cardiac ischaemia or severe valve dysfunction, severe reduction of ejection fraction, sepsis, DIC, ARD or ESRD not undergoing regularly scheduled dialysis
ASA V definition and example
Moribund patient not expected to survive without operation
Ruptured AAA, massive trauma, intra-cranial bleed with mass effect
Ischaemic bowel in the face of significant cardiac pathology or multiple organ/ system dysfunction
Propofol specificities
GABA receptor agonist
Rapid onset of anaesthesia
Pain on IV injection
Rapidly metabolised with little accumulation of metabolites
Proven anti emetic properties
Moderate myocardial depression
Widely used especially for maintaining sedation on ITU, total IV anaesthesia and for daycase surgery
Sodium thiopentone specific features
Extremely rapid onset of action making it the agent of choice for rapid sequence of induction Marked myocardial depression may occur Metabolites build up quickly Unsuitable for maintenance infusion Little analgesic effects
Ketamine features
- NMDA receptor antagonist
- May be used for induction of anaesthesia
- Has moderate to strong analgesic properties
- Produces little myocardial depression making it a suitable agent for anaesthesia in those who are haemodynamically unstable
May induce state of dissociative anaesthesia resulting in nightmares
Etomidate features
Has favorable cardiac safety profile with very little haemodynamic instability
No analgesic properties
Unsuitable for maintaining sedation as prolonged (and even brief) use may result in adrenal suppression
Post operative vomiting is common
Which surgeries only need group and save due to unlikely chance of transfusion
Hysterectomy (simple), appendicectomy, thyroidectomy, elective lower segment caesarean section, laparoscopic cholecystectomy
Which surgeries are likely to need tranfusion so need to cross-match 2 units
Salpingectomy for ruptured ectopic pregnancy, total hip replacement
Which surgeries definitely need tranfusion and so 4-6 units of blood need to be cross-matched?
Total gastrectomy, oophorectomy, oesophagectomy
Elective AAA repair, cystectomy, hepatectomy
Inhaled anaesthetic example
Halothane
Halothane side-effects
Hepatotoxicity, myocardial depression malignant hyperthermia
Intravenous anaesthetics example
Thiopental
Adverse effects of thiopental
Laryngospasm and highly lipid soluble so quickly affects the brain
Why is malignant hyperthermia often seen following administration of anaesthetic agents?
characterised by hyperpyrexia and muscle rigidity
cause by excessive release of Ca2+ from the sarcoplasmic reticulum of skeletal muscle
associated with defects in a gene on chromosome 19 encoding the ryanodine receptor, which controls Ca2+ release from the sarcoplasmic reticulum
susceptibility to malignant hyperthermia is inherited in an autosomal dominant fashion
neuroleptic malignant syndrome may have a similar aetiology
Causative agents of malignant hyperthermia
halothane
suxamethonium
other drugs: antipsychotics (neuroleptic malignant syndrome)
Ix for malignant hyperthermia
CK raised
contracture tests with halothane and caffeine
Management of malignant hyperthermia
dantrolene - prevents Ca2+ release from the sarcoplasmic reticulum
