Anaesthetics Flashcards
What to do to insulin day prior to admission for surgery?
Reduce dose by 20%
What is Suxamethonium
Depolarising neuromuscular blocker
Inhibits action of acetylcholine at the neuromuscular junction
Degraded by plasma cholinesterase and acetylcholinesterase
What airway is relatively contraindicated in base of skull fractures?
Nasopharyngeal airways
What is suxamethonium apnoea?
lack of the specific acetylcholinesterase in the plasma which acts to break down suxamethonium, terminating its muscle relaxant effect. Therefore, the effects of suxamethonium are prolonged and the patient needs to be mechanically ventilated and observed in ITU until the effects of suxamethonium wear off.
Treatment of malignant hyperthermia in suxamethonium use?
Dantrolene
When is suxamethonium contraindicated?
For patients with penetrating eye injuries or acute narrow angle glaucoma, as suxamethonium increases intra-ocular pressure
What bloods should be done in post operative ileus?
Deranged electrolytes can contribute to the development of postoperative ileus, so it is important to check potassium, magnesium and phosphate.
What is lidocaine?
Local anaesthetic and a less commonly used antiarrhythmic (affects Na channels in the axon)
Most common site for IO?
Proximal tibia
Drugs which impair wound healing?
Non steroidal anti inflammatory drugs
Steroids
Immunosupressive agents
Anti neoplastic drugs
How long before surgery should you stop oral contraceptive pill?
4 weeks
What is ASA IV?
A patient with severe systemic disease that is a constant threat to life
What is ASA V?
A moribund patient who is not expected to survive without the operation
What is ASA VI?
A declared brain-dead patient whose organs are being removed for donor purposes
Which anaesthetic agent has inherent anti-emetic properties?
Propofol
The following timeline can be used as a broad rule of thumb when determining the most likely cause of postoperative fever:
Day 1-2: ‘Wind’ - Pneumonia, aspiration, pulmonary embolism
Day 3-5: ‘Water’ - Urinary tract infection (especially if the patient was catheterised)
Day 5-7: ‘Wound’ - Infection at the surgical site or abscess formation
Day 5+: ‘Walking’ - Deep vein thrombosis or pulmonary embolism
Any time: Drugs, transfusion reactions, sepsis, line contamination.
Adverse effects of suxamethonium?
Malignant hyperthermia
Hyperkalaemia (normally transient)
What is the phsyiological problems with a ileus following gastrointestinal surgery?
Fluid sequestration and loss of electrolytes
General risk factors for VTE?
active cancer/chemotherapy
aged over 60
known blood clotting disorder (e.g. thrombophilia)
BMI over 35
dehydration
one or more significant medical comorbidities (e.g. heart disease; metabolic/endocrine pathologies; respiratory disease; acute infectious disease and inflammatory conditions)
critical care admission
use of hormone replacement therapy (HRT)
use of the combined oral contraceptive pill
varicose veins
pregnant or less than 6 weeks post-partum
Mechanism of action of Etomidate?
Potentiates GABA
Adverse effects of etomidate?
Primary adrenal suppression (secondary to reversibly inhibiting 11β-hydroxylase)
* Myoclonus
Management of post-operative ileus?
onservative with nasogastric tube insertion for stomach decompression for symptom control and placing the patient nil by mouth to allow bowel rest. The recommencement of fluids/light diet should be in stages and guided by the clinical state of the patient.
What do patient’s taking prednisolone require during surgery?
Hydrocortisone to prevent an addisonian crisis
Adverse effects of nitrous oxide?
May diffuse into gas-filled body compartments → increase in pressure. Should therefore be avoided in certain conditions e.g. pneumothorax
A 2% strength liquid medicine means what?
2g of the drug are dissolved in 100ml
Adverse effects of volatile liquid anaesthetics?
- Myocardial depression
- Malignant hyperthermia
- Halothane (not commonly used now) is hepatotoxic
Which anaesthetic agent has a favorable cardiac safety profile with very little haemodynamic instability
Etomidate
What agent reverses the action of benzodiazepines?
Flumazenil
What inhaled agent is associated with hepatoxocicity
Halothane
Local anesthetic toxicity can be treated with what?
IV 20% lipid emulsion
What to do with patients on sulfonylureas on day of surgery if morning operation?
If taken once daily in the morning - omit the dose that
day
If taken twice daily - omit the morning dose that day
What can CT scans identifiy as post op complications?
identification of intra-abdominal abscesses, air and if luminal contrast is used an anastamotic leak
Things to think about in airway when giving anaesthetics
Teeth
GORD
Not fasting- 6 hours food, 2 hours fluid
Delayed emptying- Parasympathetic and sympathetic. Drugs could delay, some people. Rest and digest- So stress causes delay
Important conditions to think about in pre op
DM
COPD/Asthma
Increased BP
Arrythmias
IHD- Make sure on optimal medication. Supply and demand.
HF
Coagulation disorer
What is important in relation to IHD in anaesthetics?
Want to continue medications that dilate the coronary arteries- Isobridde mononitrate
Also want to be continuing other drugs like CCB as they dilate the heart
Beta blockers
Management of diabetes in surgry?
Switch to sliding scale insulin as been fasted so could cause hypoglycaemia
Also due to stress could cause hyperglycaemia
What to do with epipletics in seziures?
Need to consider decreased seizure threshold so consider anti epileptics
Genetic conditions to be concerned about in surgery?
Suxamethonium Apnoea
Malignant hyperthermia
What happens at an NMJ?
AP fires until gets to threshold.
Calcium comes in. Breaks troponin bind with Acetylcholine. Acetylcholine diffuses across the synapse and opens channels at other end of channel. Then get depolarisation. So ion channel releases in sarcoplasmic reticulum, calcium stores get out and then bind to troponin
What does the sarcoplasmic reticulum store
Calcium
What is missing in malignant hyperthermia?
Channel in sarcoplasmic reticiulum that takes calcium back in
What are the types of masks
Important things to remeber about fluid therapy
Give oral over IV
When to give iv fluids?
Routine maintaince
Replacement
Resuscitation
Review
Oral fluids before surgery fasting?
patients having surgery may drink clear fluids until 2 hours before their operation
clear fluids are water, fruit juice without pulp, coffee or tea without milk and ice lollies
Patients are generally advised to fast from non-clear liquids/food for at least 6 hours before surgery.
