Anaesthesia for emergency surgery

Question 1

Classify and give examples for the theatre triage system used at GSH

Answer 1

RED (< 1hr)

• Unstable bleeding GSW
• Ruptured ectopic
• Ruptured AAA
• Imminently threatened airway

ORANGE (1 - 3 hrs)

• Acute abdomen (bowl perforation)
• Threatened rupture of ectopic

YELLOW (< 6hrs)

• Stable appendix
• Open fractures

GREEN (<24 hrs)

• Closed fractures
• Changing of dressings
• Cancer surgery

BLUE
- Elective surgery (cataract / tonsillectomy etc)

Question 2

Describe the ASA fasting guidelines

Answer 2

Clear fluids - 2 hours
Breast milk - 4 hours
Non-human milk - 6 hours
Solids - 6 hours

Question 3

What is Mendelson’s syndrome

Answer 3

Aspiration of stomach contents into the respiratory system

Vomiting/regurgitation of stomach content, fluid, particulate matter into the trachea may cause hypoxia by both mechanical obstruction and an acute pulmonary inflammatory process (chemical pneumonitis) –> may progress to atelectasis and infection.

Question 4

Differentiate vomiting from regurgitation in the context of Mendelson’s syndrome

Answer 4

Vomiting

• Active process
• Lighter planes of anaesthesia (induction/emergeance)
• expulsion of gastric contents into pharynx by contraction of the diaphragm

Regurgitation

• Passive process
• Occurs at any time - deeper planes
• Laryngeal reflexes are reduced or paralysed

Question 5

In the context of anaesthetics classify the situations during which it is assumed that there is a full stomach

Answer 5

INTAKE
- recent fluid/solid intake

ABNORMAL PERISTALSIS

• Peritonitis
• Ileus
• —–> Postoperative
• —–> Metabolic (hypoK, Uraemia, DKA)
• —–> Drug induced (Opioids/anticholinergics)

OBSTRUCTED PERISTALSIS

• Gastric Ca
• Pyloric stenosis
• Obstruction (Small or large bowel)

DELAYED GASTRIC EMPTYING

• Shock
• Trauma
• Diabetes
• Pregnancy and labour
• Fear/pain/anxiety
• Opioids

Question 6

Why is prolonged muscle relaxation more common in emergency (vs elective) surgery

Answer 6

1. Hypothermia
2. Electrolyte abN
3. Drug interactions
4. Reduced clearance d/t impaired hepatic/renal fxn

Question 7

In a patient in whom RSI was performed, what is paramount during emergence of this patient

Answer 7

PREVENT ASPIRATION

1. Adequate reversal
2. Breathing spontaneously (FiO2 < 0.4 and SaO2 > 95%)
3. Suctioned oro and nasopharynx
4. Fully awake: responds to verbal commands (open eyes/nods or lifts head)

Once all the above are confirmed - Remove ETT during a manual positive pressure breath.

Question 8

Differentiate primary and secondary brain injury

Answer 8

Primary
- Irreversible injury of neural/supportive/vascular tissues

Secondary

• Following primary injury, the injured brain is susceptible in the following days to events that would have no effect on normal brain tissue
  1. Hypoxia
  2. Hypotension
  3. Hyperthermia
  4. Convulsions
  5. Hyper and hypoglycaemia

Question 9

Describe the targets with regard to the prevention of secondary brain injury

Answer 9

Airway

• Intubate if GCS < 8
• Remember C-spine (manual in-line)

Breathing

• SaO2 > 95%
• Normocapnoea

Circulation
- MAP > 90mmHg
Rx SBP < 90 mmHg aggresively

Disability
- Seizure prophylaxis: Phenytoin 20mg/kg load

Exposure
- Maintain normothermia

Fluid

• Mannitol 0.5mg/kg if deteriorating neurological status with catherter in situ
• NaCl is hypertonic therefore fluid of choice

Glucose
- Maitain euglycaemia

Question 10

What is the formula for cerebral perfusion pressure (CPP)§

Answer 10

CPP = MAP - ICP or CVP (whichever is greater)

Question 11

Describe when and how mannitol is given in TBI

Answer 11

Deteriorating neurology (decreasing LOC with localizing signs)

Dose: 0.5 mg/kg (± 200 ml of mannitol 20%)

Urinary catheter in situ

May repeat the same dose if further neurological deterioration occurs