(Originally presented by Dr Dave Saunders)

Definition

Phaeochromocytoma: Catecholamine secreting tumour of the Adrenal Medulla

Paragangliomas: Extra-Adrenal paraganglia which may produce catecholamines

Incidence 0.2 per 100 000 people.

Rule of Ten’s (no longer totally accurate)

  • 10% of phaeochromocytoma’s are extra-adrenal (i.e. paraganglioma) (actually its 24%)
  • 10% are malignant (actually 29%)
  • 10% are bilateral
  • 10% are found in normotensive patients
  • 10% are familial (actually 32%)

Pre-operative – Optimisation

Arterial pressure control and volume expansion

  • Phenoxybenzamine
    • Non-selective long acting alpha blockade
    • Should be ceased 24-48hrs prior to OT due to long half life
    • Can lead to post operative refractory hypotension
  • Doxazocin
    • Alpha-1 selective alpha blocker
    • PRESCRIPT trial suggested less haemodynamic instability with Doxazocin compared to Phenoxybenzamine but no statistically significant clinical outcomes
  • Calcium Channel blockers
    • Used in conjunction with alpha blockade
    • Useful for patients with severe orthostatic hypotension (with alpha blockade)
  • High sodium diet and high fluid intake to maintain blood volume

Heart rate and arrhythmia control

  • Tachycardia can occur due to catecholamine secreting tumour or alpha blockade
  • Selective B1 agents can be used (i.e. Metoprolol, Esmolol, Atenolol)
  • However it must be commenced after complete alpha blockade to avoid hypertensive crisis

Assessment and optimisation of myocardial function

  • TTE / TOE is considered mandatory
  • Some level of diastolic dysfunction occurs in the majority of patients
  • LV systolic dysfunction occurs in around 10%
  • Hypertrophic cardiomyopathy (secondary to chronic hypertension) is most frequent
  • Some case reports of Atypical Takotsubo cardiomyopathy

Reversal of glucose and electrolyte disturbances

  • Glucose homeostasis mediated through alpha and beta
    • Increased glycogenolysis (alpha-1)
    • Impaired insulin release (alpha-2)
    • Lipolosys (beta-1)
    • Increased glucagon release with peripheral insulin resistance (beta-2)
  • Monitor and treat hyperglycaemia

Assessment of Adequate Optimisation

  • α-Blockade is commenced at least 7–14 days before surgery (may need longer for cardiomyopathy or refractory hypertension)
  • The Roizen criteria have historically been utilised however are now slightly dated.
    • BP <160/90 consistently
    • Presence of orthostatic hypotension with drop in Systolic BP at least 15% (not <80mmHg)
    • ECG with no ST or T wave changes for 2 weeks
  • The Roizen criteria are slightly dated. Contemporar
    • BP targets should be tighter (<130/80 mmHg seated)
    • Orthostatic hypotension is not a necessity
    • ST or T wave changes may reflect inverted Takotsubo cardiomyopathy rather than ischaemia.

Perioperative

Positioning

  • Lateral
  • Kneeling prone

Hypertensive Episode During Procedure – Avoid Catecholamine release

  • Surgically handling of tumour can induce catecholamine release
  • Minimise Anaesthetic-induced catecholamine release stimulation
    • Laryngoscope
    • Coughing
    • Pain
    • Increased intra-abdominal pressures
  • Drugs to avoid
    • Desflurane
    • Ketamine
    • Morphine
    • Pethidine
    • Atracurium
    • Pancuronium
    • Ephedrine
    • Droperidol
    • Metoclopramide
    • Cocaine
    • (Suxamethonium: theoretical risk of provoking tumour catecholamine release however has been used without complications)
  • Adjuncts to treat Hypertension
    • MgSO4
    • Remifentanil
    • Dexmedetomidine
    • Phentolamine
    • SNP
    • GTN
    • Nicardipine
    • Esmolol

Hypotensive Episodes – important after tumour devascularisation

  • Treatment
    • Reduce hypotensive agents
    • Fluid optimisation
    • Utilise Noradrenaline, metaraminol, ephedrine etc. usual vasopressors and ionotropes
    • However consider Vasopressin for catecholamine resistant hypotension (bolus of 0.4 to 20 units followed by infusion of 1-3 micro units/Kg/min)
  • Catecholamine Resistant Hypotension
    • Residual alpha blockade (especially if phenoxybenzamine used)
    • Abrupt catecholamine deficiency
    • Catecholamine receptor down-regulation after chronically elevated catecholamine levels

Key Take Home Messages

  1. Ensure adequate preoperative optimisation
  2. Ensure careful planning for managing BP
    • Hypertension – first stage
    • Hypotension – second stage

Further reading

  1. BJA – Phaeochromocytoma
  2. PRESCRIPT Trial