Appendicitis

What is the pathophysiology of appendicitis ?

• Luminal obstruction - tumour / lymphoid hyperplasia / fecalith (stone)

• Mucus secretion continues + bacteria overgrowth eg E.coli

• This increases luminal pressure

• Causing venous and lymphatic obstruction, and ischemia

• Bacteria invade ishcemic wall and multiply

• Necrosis occurs from prolonged ischemia

• If untreated increased pressure = perforation = bacteria into peritoneum = sepsis

What treatment would you give for appendicitis?

Pain relief

Ondansetron

What are the benefits of morphine?

• Strong analgesia reducing patient discomfort

• Does not mask diagnosis

• Reduces release of pain associated hormones such as adrenaline / noradrenaline = more stable observations like HR, RR

What are the risks of morphine?

• Respiratory depression due to suppression of respiratory centre in medulla

• Reduced GCS due to it causing CNS depression that effects the reticular activating system responsible for alertness

• Hypotension releases histamines = vasodilation. Dilates veins lowering preload + cardiac output

• Nausea + vomiting stimulates chemoreceptor trigger zone in brain and reducing gastric motility

• Constipation reduces gastric motility +peristalsis

• Urinary retention increased urethral sphincter tone

What are the benefits of ondansetron?

• Effective anti-emetic by blocking serotonin receptors in chemoreceptor trigger zone in brain + gut

• Improves patient comfort

What are the risks of ondansetron?

• Headache due to serotonin receptor blockade in CNS = altered blood vessel tone

• Constipation - 5HT receptor antagonist reduces peristalsis + secretions

• QT interval prolongation - blocks potassium channels = slowed ventricular repolarisation = prolonged QT

• Seizures due to blocking 5HT3 receptors in CNS meaning neurones normally controlled by serotonin have increased excitability

• Bradycardia increased vagal tone, slows SA node firing. OT prolonged = prolonged repolarisation