ADRENALS: SURGERY OF THE ADRENALS
Pre-operative and post-operative management of Pheochromocytoma
- See Pheochromocytoma Chapter Notes
- Excessive secretion of catecholamines from chromaffin tissue may result in tachycardia, diaphoresis, headache, hypertension, cardiac arrhythmias, left ventricular dysfunction, and impaired glucose tolerance.
- Preoperative cardiac workup, including electrocardiography and echocardiography, and assessment of hypertension-induced end-organ dysfunction are indicated.
- Preoperative sympatholytic therapy with α-adrenergic blockers for at least 2 weeks before surgery helps in both hemodynamic and glucose control and should be continued until the day of surgery
- Phenoxybenzamine is time proven to be safe and effective but has its associated problems. Its nonselective nature may lead to tachycardia and β-adrenergic blockade may be necessary. Being an irreversible noncompetitive α-adrenergic blocker, prolonged hypotension in the immediate postoperative period and central nervous system effects such as somnolence may be expected.
- Newer selective and competitive α1-adrenergic blockers such as doxazosin, prazosin, and terazosin obviate the drug-induced need for β-blockade.
- β-Adrenergic blockade, if needed, must be given with caution in patients with myocardial depression and started only after phenoxybenzamine therapy.
- Intraoperatively, hypertensive episodes should be anticipated and can be controlled with intravenous drugs with rapid onset and short half-life such as nitroprusside, phentolamine, nitroglycerin, and nicardipine. Temporary cessation of surgical manipulation of the pheochromocytoma may be necessary. Short-acting β-blockers such as labetalol and esmolol are also good choices.
- Aggressive fluid management with volume repletion is necessary after removal of pheochromocytoma because hypotension can occur as a result of sudden loss of tonic vasoconstriction.
- Postoperatively, fluid administration and use of vasopressors such as phenylephrine, guided by invasive monitoring, are useful to manage hypotension. Electrolyte abnormalities and hypoglycemia should be corrected. It is not uncommon for patients to remain hypertensive postoperatively, and antihypertensive management should be continued.
Pre-operative Management of hyperaldosteronism
- An aldosterone antagonist (spironolactone) should be started at least 1-2 weeks before surgery, especially in patients on long-term angiotensin-converting enzyme inhibitors
Oncologic Principles of Resection for Adrenal Cortical Carcinoma
- No touch technique
- Preservation of the intact peritoneum on the anterior surface of the adrenal gland if no evidence of invasion through the overlying peritoneal layer
- En bloc resection of tumor with a wide margin of surrounding benign tissue outside the tumor capsule
- Strict preservation of an intact tumor capsule
- Exclusion of the remainder of the peritoneal cavity as much as possible using barriers such as laparotomy pads, plastic barriers, or drapes
- Minimizing of bleeding and fluid spillage into the peritoneal cavity
- Change of gloves, gowns, and instruments after removal of the tumor and prior to closure of the abdomen.
Surgical anatomy
- The right adrenal vein is short, drains into the posterior segment of the inferior vena cava and is usually not exposed until the adrenal gland is mobilized
- The longer left adrenal vein joins with the inferior phrenic vein and enters the cranial aspect of the left renal vein
- If doing bilateral adrenalectomy, left side should be first as more difficult
Approach
- Laparoscopic adrenalectomy should be the gold standard for the surgical removal of adrenal masses [Campbell’s 11th edition suggests that adrenal cancer should not be done laparoscopically]
- Contraindications for Laparoscopic Adrenalectomy
- Relative
- Large tumor (>6 cm)
- Localized adrenal cortical carcinoma without adrenal vein or vena caval involvement
- Morbid obesity
- Malignant pheochromocytoma
- Virilizing adrenal tumor (70-80% of these tumors are actually functional adrenal cortical carcinoma)
- Significant abdominal adhesion
- History of recurrent pyelonephritis
- Pregnancy
- Absolute
- Local recurrence of a previously resected adrenal mass
- Invasive adrenal cortical carcinoma with evidence of invasion of neighboring organs or renal artery or vena caval involvement
- Contraindications to establishment of pneumoperitoneum§
- Cardiac failure
- Pulmonary failure
- Renal failure
- Hemodynamic instability/shock
- Increased intracranial pressure
- Acute intestinal obstruction with dilated bowel loops
- Large pelvic mass
- Soft tissue infection at port sites
- Acute glaucoma
- Recurrent spontaneous pneumothorax
- Vascular endocranial malformation
- Hypertensive retinopathy
- Expected (extensive) adhesions from a previous abdominal surgery
- Abdominal aortic aneurysm (may be associated with increased risk of vascular rupture)
Open adrenalectomy
- Broadly classified into transperitoneal and retroperitoneal approaches
- Transperitoneal approaches
- Include the anterior transabdominal and thoracoabdominal approaches
- Advantages
- Excellent surgical exposure
- Better access to the hilum and great vessels
- Disadvantage
- Higher risk of intra-abdominal organ injury and ileus
- Retroperitoneal approaches
- Include the flank and posterior lumbodorsal approaches
- Advantages
- Reduced risk of visceral and bowel injuries by avoiding entry into the peritoneum
- Less ileus and shorter hospitalization
- Ideal for the morbidly obese patient in whom the abdominal panniculus will fall forward in a flank or prone position
- Reduced hemodynamic and respiratory morbidity in the absence of pneumoperitoneum
- Dense intraperitoneal adhesions arising from previous surgery or inflammation are averted by operating in the retroperitoneum
- Disadvantage
- Smaller operative field which makes dissection of large tumors difficult
- Posterior lumbodorsal approach should not be used for large tumors or adrenal cortical carcinoma
- The main advantage of the flank approach over the posterior approach is the ease of conversion into the transperitoneal approach should difficulties be encountered. In contrast, the prone posterior lumbodorsal approach allows for bilateral adrenalectomy without patient repositioning.
- All patients undergoing surgery for large adrenal masses must be counseled about the possibility of concurrent en bloc nephrectomy
Partial adrenalectomy
- Unilateral adrenalectomy is often well tolerated and should be considered as the gold standard in the treatment of functioning or malignant adrenal tumors.
- Indications for partial adrenalectomy (3):
- Bilateral adrenal tumors
- Solitary adrenal gland
- Familial syndromes (such as von Hippel-Lindau disease, familial pheochromocytoma, and multiple endocrine neoplasia type IIA)
- Patients with bilateral adrenalectomy will require lifelong adrenal replacement therapy.
- Fixed daily dosing of steroids is associated with overdosing, which may result in osteoporosis, obesity, and Cushing syndrome, and with underdosing in times of stress. Life-threatening Addisonian crisis can occur.
- Patients after bilateral adrenalectomy continue to report poorer quality of life as compared to the general population.
- The amount of adrenal tissue that must be left behind after partial adrenalectomy to avoid insufficiency is not known.
Ablative therapy for adrenal tumours
- Current indications for ablative therapy for adrenal tumors include patients with small tumors not keen on or suitable for surgery and palliation of painful metastases not amenable to resection.
- The 3 major thermal ablative techniques currently used are radiofrequency ablation (RFA), cryoablation, and microwave ablation.
- RFA utilizes frictional energy created by oscillating tissue ions to supply destructive heat to target tissue, with target tissue temperature ranging from 60-100° C resulting in protein and enzymatic degradation and cell death
- Cryoablation relies on rapid freezing and thawing to cause rupture of cell membranes resulting in cell death. The main advantage of this technique is the ability to follow iceball formation in real time with CT imaging.
- Microwave ablation creates an alternating electric field that causes oscillation of surrounding water dipoles resulting in tissue heating. Some have suggested that advantages of microwave ablation include the potential for larger ablation volumes, decreased procedural pain, and the potential to treat cystic lesions
Surgery for pheochromocytoma
- Early
ligation of the main adrenal vein and minimal manipulation
of the affected adrenal are important.
- Catecholamine release can be caused by thermal injury to the adrenal in the absence of pheochromocytoma
- It is important to notify anesthesia when the adrenal vein is ligated
Questions
- Which blood vessel should be ligated first during an adrenalectomy?
Answers
- Which blood vessel should be ligated first during an adrenalectomy?
References
- Wein AJ, Kavoussi LR, Partin AW, Peters CA (eds): CAMPBELL-WALSH UROLOGY, ed 11. Philadelphia, Elsevier, 2015, chap 66
