Carcinoid

 

Disease:

Pathophysiology

·     Carcinoid = carcinoma-like

·     Neuroendocrine tumour

·     Does metastasise but slow-growing

·     Secretes serotonin > histamine > many others

Location

·     Foregut: stomach, lung

·     Midgut: small bowel (commonest) and prox large bowel

·     Hindgut: distal large bowel

Presentation

Asymptomatic:

·     *Portal drainage = hormones inactive*

·     Often found late

Bowel tumour:

·     Bleeding

·     Obstruction

Hormone secretion: (20%)

·     *Extra-portal drainage = hormones active*

·     Carcinoid syndrome

o   Ax: exercise, tyramine foods

o   Hx: flushing, diarrhoea, lacrimation, dyspnoea

o   Ex: tachycardia, labile BP, fever, bronchospasm

·     Carcinoid crisis

o   Exaggerated form

o   Lethal

o   Precipitant: drugs, physiological insult, physical manipulation

·     Right heart fibrosis

o   Valve disease (mixed TV & PV)

o   Arrhythmias (SVT)

o   Constrictive pericarditis

Diagnosis

Disease:

·     Imaging: CT

·     Urine: metabolites

Complications:

·     Blood tests: FBE (? marrow met), UEC (? diarrhoea), LFT (? liver met)

·     ECG (? RV strain)

·     TTE (? RVH, valve disease)

Octreotide

Effects:

·     Wanted: ↓splanchnic flow, ↓mediator release, ↓many hormones

·     Unwanted: conduction delay (↓HR, ↑PR, ↑QTc), GIT upset

Dosing:

·     At home: PO

·     On arrival: IV 50mcg/h for 12 hours

·     At induction: IV 300-500mcg

·     At crisis: IV 100mcg

 

Anaesthesia:

Avoid crisis

Reflex suppression:

·     Thoracic epidural

·     Octreotide at induction

·     Opioid at laryngoscopy

Avoid stimulation:

·     Surgical handling

·     Pain

·     Hypovolaemia

·     Hypoxaemia

·     Hypercapnoea

·     Hypothermia

Avoid secretagogues:

·     Morphine

·     Atracurium

·     Suxamethonium

·     Any vasopressors except phenylephrine and vasopressin

Anticipate bleeding

·     Risk if central venous hypertension + liver surgery

·     Fix severe valve disease before carcinoid surgery

If hypotension

·     Yes: fluid, octreotide, phenylephrine, vasopressin

·     No: ephedrine, noradrenaline, adrenaline (unpredictable ↑↑/↓↓)

·     Not sure about metaraminol

If bronchospasm

·     Yes: octreotide, anti-muscarinic, glucocorticoid, anti-histamine

·     No: beta agonist, phosphodiesterase inhibitor

 

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