Anaesthesia Flashcards
What are the inhaled anaesthetics used for induction and maintenance of anaesthesia?
Volatile liquid anaesthetics (isoflurane, desflurane, sevoflurane)
ADRs of Volatile liquid anaesthetics (isoflurane, desflurane, sevoflurane)
- Myocardial depression
- Malignant hyperthermia
- Halothane (not commonly used now) is hepatotoxic
What are the inhaled anaesthetics used for maintenance of anaesthesia and analgesia?
Nitrous oxide
ADRs of nitrous oxide
May diffuse into gas-filled body compartments → increase in pressure.
Should therefore be avoided in certain conditions e.g.pneumothorax
What intravenous anaesthetics potentiates GABAA?
- Propofol
- Thiopental
- Etomidate
When is Propfol used?
Very common induction agent for general anaesthesia and also used extensively in intensive care for ventilated patients
Has some anti-emetic effects - useful for patients with a high risk of post-operative vomiting
ADRs of propofol
- Pain on injection (due to activation of the pain receptor TRPA1)
- Hypotension
ADRs of Thiopental
Laryngospasm
When is Etomidate used?
Causes less hypotension than propofol and thiopental during induction and is therefore often used in cases of haemodynamic instability
ADRs of Etomidate
- Primary adrenal suppression (secondary to reversibly inhibiting 11β-hydroxylase)
- Myoclonus
When is ketamine used?
- Acts as a dissociative anaesthetic.
- Doesn’t cause a drop in blood pressure so useful in trauma
ADRs of Ketamine
- Disorientation
- Hallucinations
What are the rules for oral fluids before surgery
Oral fluids:
- patients having surgery may drink clear fluids until 2 hours before their operation
- drinking clear fluids before the operation can help reduce headaches, nausea and vomiting afterwards
- 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.
What are the symptoms of postoperative ileus?
Abdo pain
Bloating
Vomiting
Following bowel surgery
Tx of postoperative ileus
nil-by-mouth initially, may progress to small sips of clear fluids
Nasogastric tube if vomiting
IV flud is to maintain normovolaemia- additives to correct any electrolyte disturbances
total parenteral nutrition- occasionally required for prolonged/severe cases
What is the contraindication for Laryngeal mask?
Provides poor control against reflux of gastric contents therefore is unsuitable in non fasted patients
When should women stop their COCP/HRT before surgery?
4 weeks before surgery
What is required prior to surgery for patients taking prednisolone?
Hydrocortisone supplementation
Tx of confirmed anastomotic leak
This is a surgical emergency and the patient must return to theatre as soon as possible
How should Total parenteral nutrition be administered?
via a central vein as it is strongly phlebitic
When might an ECG be done as part of their pre-operative assessment?
- Patients over the age of 65 may need an ECG before major surgery.
- Patients with renal disease may need a full blood count and an ECG depending on their ASA grade even before intermediate surgery.
- Patients with diabetes may need an ECG before intermediate surgery.
Who will usually require a variable rate intravenous insulin infusion (VRIII)
patients on insulin who are either undergoing major procedures (surgery requiring a long fasting period of more than one missed meal) or whose diabetes is poorly controlled
How should patients with oral anti-diabetic drugs be managed before surgery?
most patients taking only oral antidiabetic drugs may be managed by manipulating medication on the day of surgery, depending on the particular drug
Early causes of post-op pyrexia (0-5 days)
- Blood transfusion
- Cellulitis
- Urinary tract infection
- Physiological systemic inflammatory reaction (usually within a day following the operation)
- Pulmonary atelectasis - this if often listed but the evidence base to support this link is limited
Late causes of post-op pyrexia (>5 days)
- Venous thromboembolism
- Pneumonia
- Wound infection
- Anastomotic leak
What should be done to once-daily insulin dose on the day before and the day of surgery?
once-daily insulin dose should generally be reduced by 20% on the day before and the day of surgery
What to do with metformin on the day of the surgery?
Surgery / metformin on day of surgery:
OD or BD: take as normal
TDS: miss lunchtime dose
assumes only one meal will be missed during surgery, eGFR > 60 and no contrast during procedur
Tx of Local anesthetic toxicity
IV 20% lipid emulsion
Side effect of suxamethonium and tx
Malignant hyperthermia is a recognised serious side effect of suxamethonium among those who are susceptible and requires IV dantrolene therapy
Maintenance fluids for adult
25-30 ml/kg/day of water
