anaesthetic management of pheochromocytoma

Moderator: Residents:Dr Preethy Dr Shakthivel Dr Indranil Dr Ashwini

SURGERY: Open vs Laparoscopic

Open lateral retroperitoneal approach- Traditional.

Transabdominal approach necessary in a few patients.

Laparoscopic transperitoneal excision feasible now-a-days.

Open surgery- Quicker, shorter duration of tumour handling, longer

duration of postoperative stay.

Laparoscopic surgery- Persistent and sustained tumour handling for longer

duration, may be very difficult, shorter postoperative stay.

PRE ANESTHETIC ASSESSMENT

Verification of history Severity of hypertension Adequacy of α blockade End organ damage Cardiology evaluation-

ECG CXR Echocardiography

Renal function- Urea Creatinine Electrolytes

Serial hematocrit Blood sugar, Calcium

Intraoperative Principles

Administer an anxiolytic

Place an intra-arterial catheter before induction

Place an intravenous catheter for antihypertensive administration

Place a central venous catheter for intravascular volume monitoring

Treat hemodynamic fluctuations with antihypertensives and

adrenergic antagonists

Monitor for hypotension and hypoglycemia after tumor isolation

Premedication:

Sedation, anxiolysis, assurance prevent marked hemodynamic

changes intraoperatively.

Benzodiazepine preferred

Opioids can provoke CCA release

Buprenorphine- potent analgesic with anxiolytic & sedative

properties, cardiovascularly more stable

Phenoxybenzamine should be withdrawn 48 hours prior to surgery

Last dose of α adrenergic blocker to be given at night prior to surgery.

INTRAOPERATIVE MANAGEMENT

Teamwork between surgeon, anesthesiologist, physician and

endocrinologist.

First successful operation by Roux in 1926.

Various techniques tried till date.

Rational technique-

Combined regional and general anesthesia

Selective adrenergic antagonists to control hemodynamic surges.

Patient to be shifted cautiously

ECG, pulse oximetry, NIBP

Two large bore intravenous catheters

Arterial catheter & central venous catheter put under LA

PA catheter mostly not needed

May be useful in patients with preoperative cardiovascular

compromise or severe LV dysfunction

Epidural catheter before/after GA at mid (T9-10) or low(T12-L1)

thoracic level

Induction

Should be smooth CCA surge during induction, hypotension due to volume contraction

unlikely in an adequately prepared patient Preoxygenation Opioids-

Morphine/Pethidine: Histamine release Fentanyl: Most commonly used (2-5 µg/kg) Alfentanil/Sufentanil/Remifentanil

Induction agents- Thiopentone : Can cause histamine release Etomidate: Cardiovascularly stable, but, pain on injection Propofol: Logical choice Midazolam: Useful for co-induction

Muscle relaxants-

Succinylcholine: Sympathetic stimulation, muscle fasciculation

Atracurium, Mivacurium: Histamine release

Pancuronium: Indirect Sympathomimetic action

Vecuronium, Rocuronium, Cisatracurium: Suitable agents

Positioning

Must be done carefully

Transabdominal approach-

Supine, one or both arms tucked alongside body, flank elevated 30 degrees,

table flexed to open up space between costal margin and ASIS

Posterior approach-

Not recommended, prone, table flexed at waist

Thoracoabdominal approach-

Side to be operated elevated 45 degree, arm slinged above head

Laparoscopic approach-

Full lateral, operative side uppermost, operative side hyperextended till

flank musculature slightly taut

Monitoring

ECG

Pulse oximetry

Invasive BP

CVP

Urine output

Temperature

Inspired oxygen conc.

EtCO2

EtAA

PA catheter (+/-)

Blood sugar

Maintenance

Anesthetic depth more important than agent

Halothane/Enflurane- Arrhythmogenic

Isoflurane- Commonly used

Sevoflurane- Preferred due to rapid titrability of anesthetic depth,

hemodynamics

Desflurane- Causes significant sympathetic stimulation

N2O- Not contraindicated

Air/Oxygen mixture, FiO2 0.5, TV 7-10ml/kg, EtCO2 35-38mm Hg

Epidural continuous infusion/repeated boluses with bupivacaine

with/without fentanyl

Further IV opioids usually not needed

Control of Perioperative CCA Release

CCA release during tumour handling inevitable despite adequate preoperative

control

Noxious stimuli- Hypertension: Deepening anesthesia

Tumour handling- ↑SVR, PCWP; ↓CO: Careful handling, vasodilators

Direct vasodilators-

Sodium Nitroprusside: Potent arterio-venodilator, rapid onset, brief action,

cyanide toxicity uncommon with small quantity used (Initial 0.5 to

1.5µg/kg/min, mean 3 to 5 µg/kg/min)

Nitroglycerine: Mainly affects capacitance vessels, rapid acting, large doses

may be needed

α adrenergic antagonists-

Phentolamine: Competitive α1 & weak α2 receptor antagonist, as infusion or 1-

2 mg boluses, causes tachycardia.

β adrenergic antagonists- Help control tachycardia/tachyarrhythmias

Esmolol: Ultrashort acting β1 antagonist. Rapid titrability. Uniquely

suitable.

Bolus 500µg/kg, infusion 50-200µg/kg/min

Metoprolol 1-2 mg boluses

Labetalol ( 0.25 mg/kg, upto 20 mg over a period of 10 min)

Atenolol (2.5 to 10 mg), propranolol (1 to 10 mg) also used

Calcium channel blockers- little reduction in preload, less potential for

overshoot hypotension, no rebound hypertension, less increase in heart rate,

absence of cyanide toxicity

Nicardipine: Inhibits CCA release from adrenal medullary cells in vitro,

Intra-operative 2.5-7.5µg/kg/min, onset 1 to 5 min, duration 3-6 hours

Dopa-1 receptor agonist-

Fenoldopam: Peripheral vasodilation, ↑Renal blood flow. Undesirable

diuresis

Magnesium sulphate-

Pioneered by James et al in 1960

Inhibits CCA release from adrenal medulla, alters adrenergic receptor

response

Loading dose 40-60mg/kg followed by 1-2g/hr continuous infusion

Target blood level 2-4 mmol/L

Additional doses necessary during tumour handling

Has been used in pregnant patients, patients with CAD

Other drugs reported-

Diltiazem, Prostaglandin E1, Midazolam/Sufentanil infusion,

Midazolam/Fentanyl infusion, Propofol/Fentanyl infusion, MgSO4/GTN

infusion, Desflurane, Sevoflurane with adenosine triphophate, Esmolol

infusion

Post Resection Hypotension

After adrenal vein ligation and removal of tumour Reasons-

Suppression of contralateral adrenal gland Downregulation of adrenergic receptors Effect of preoperative adrenoceptor antagonists Sudden increase in venous capacitance

Mostly amenable to modest fluid load and discontinuation of vasodilators Blood replacement according to losses Vasopressor if hypotension unresponsive to fluid

Noradrenaline Phenylephrine Dopamine Angiotensin II agonist

POST OPERATIVE MANAGEMENT

Reversal depends upon preoperative state and intraoperative course Neostigmine and Glycopyrrolate Shift to ICU/HDU Most important post-operative complications-

Hypertension: Approx. 50% patients Recovery from anesthesia Pain- Opioids, epidural analgesia, clonidine Persistence of high plasma CCA level- restart antihypertensives Residual tumour- further evaluation and work up

Hypotension: Supression of contralateral adrenal Downregulation of adrenoceptors Persistent effect of preoperative adrenergic blockade Intra-abdominal bleed- high index of suspicion

Hypoglycemia

Disappearence of pancreatic β cell suppression

Lipolysis, glycogenolysis no longer present

Slow emergence, lethargy

β-blockers impair recovery, mask symptoms

Encephalopathy may occur

Frequent monitoring of blood glucose needed

Glucose containing IV fluids started after tumour removal

Perioperative steroid replacement in bilateral adrenalectomy

SPECIAL CONSIDERATIONS

Pheochromocytoma patient for non-pheo surgery- Elective surgery to be postponed and elective resection of

pheochromocytoma planned Patients for emergency surgery should be tried to be optimised as far as

possible before surgery Pheochromocytoma in pregnancy-

Misreading of warning symptoms common Maternal mortality 2 to 4% if diagnosed antenatally, 14 to 25% if

diagnosed intrapartum or postnatally Early pregnancy: Medical optimisation for 1to 2 weeks f/b resection

before 24th week Late pregnancy: Medical optimisation till fetus mature, f/b elective

caesarean and resection at same sitting Vaginal delivery preferrably avoided

Cardiac pheochromocytoma-

Significant morbidity, mortality

Thoracolaparotomy, CPB with cardioplegia

Exsanguination, myocardial infarction

Orthotopic Cardiac Transplantation can be considered

Carotid Body Tumour and Paraganglionoma excision-

Major hemorrhage

Need for carotid cross clamping, grafting

Postoperative complications: Airway compromise, disturbed

baroreceptor function, cerebral ischemia

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