Conn’s syndrome is associated with hypersecretion of aldosterone. It presents with severe hypokalaemia and signs of sodium retention like hypertension. This is a case report of successfully conducting laparoscopic left adrenalectomy on a 52 year old male patient who was a known hypertensive with an ejection fraction of 42%, with severe generalised muscle weakness and history of quadriplegia three months ago.
Case Report
A 52 year old male patient, weighing 82 kg, orthopaedic surgeon by profession, presented with the chief complaints of generalized muscle weakness since six months, alongwith sudden onset of dull aching pain in the lower abdomen since three months.
He was a known case of hypertension since four years controlled with daily dosage of 50 mg Atenolol. Six months ago, he experienced generalized bodyache which was persistent and non-progressive. The treating physician then switched him over to 3.25 mg of tablet carvedilol twice a day. Three months later, he had sudden onset of quadriplegia and on investigating severe hypokalaemia was revealed with serum potassium levels of 1.5 mEq/L. Potassium supplements were infused intravenously and the patient recovered completely in four days. He was thus diagnosed to be a case of hypokalaemic paralysis and tablet spironolactone 300 mg was added in his medication. On further investigation, CT scan of abdomen revealed 3 x 4 cm mass arising from left adrenal gland - suggestive of adenoma with Conn’s syndrome and was advised left adrenalectomy. He was then posted for laparoscopic left adrenalectomy.
Preoperative Evaluation
The patient was well built and nourished with pulse rate of 80 beats per minute and blood pressure of 140/90 mmHg. No other abnormality was revealed on systemic examination. His neck movements were adequate, hyomental distance and thyromental distance were 5 cm and 6 cm respectively and he had MPC Grade II.
Investigations
Haemogram, liver function tests, renal function tests and coagulation profile were within normal limits. Serum sodium was 132 mEq/L and Serum potassium was 5 mEq/L Chest radiograph was normal. ECG revealed normal rhythm with flattening of T waves in leads II, III, V1, V2 and V3. 2 D-echocardiography suggested diffuse hypokinesia with ejection fraction of 42%. His medication included tablet carvedilol and spironolactone.
Anaesthesia Management
The patient received tablet diazepam 10 mg orally alongwith his usual antihypertensive therapy on the morning of surgery. ECG, pulseoximeter and NIBP monitors were attached. A peripheral intravenous line was placed in left upper limb. Corticosteroid replacement was started at induction with hydrocortisone 100 mg. Injection midazolam 1.5 mg was given for sedation and injection pentazocine 30 mg was given for analgesia. Anaesthesia was induced with propofol 160 mg followed by suxamethonium. Intubation was achieved with size 9.5 cuffed PVC endotracheal tube and maintained with O2, N2O, isoflurane and vecuronium. Left radial artery was cannulated for invasive blood pressure monitoring. The patient was placed in right lateral position for the excision of left adrenal gland laparoscopically. Serum potassium, glucose, acid base and arterial blood gas monitoring which was analyzed regularly were normal. There were no significant changes in the vital parameters even during creation of pneumoperitoneum or handling of adrenal mass. Adequate iv fluids and colloids were infused during the surgery which lasted for four hours and caused blood loss of about 1000 ml. After fulfilling all the criteria for reversal, the patient was extubated and monitored in the recovery room for 72 hours without any fluctuations in haemodynamics and potassium levels. Spironolactone was stopped 24 hours after the surgery. Postoperative analgesia was achieved with injection diclofenac sodium 75 mg thrice a day. The patient was discharged on the fifth day. Further follow up till date revealed no alterations in the potassium levels and no symptoms suggestive of hypoaldosteronism.
Discussion
A patient presenting with muscle weakness and hypertension, first reported by Canadian physician Conn, lead to recognition of primary aldosteronism.1 In this condition, an excess of aldosterone is produced from either an adenoma or hyperplasia of adrenal gland, resulting in hypertension and hypokalaemia. Hypertension, hypokalaemia and excessive aldosterone secretion each have detrimental effect on the cardiovascular system.2 Muscle weakness of variable degree is the usual presenting symptom, often associated with hypertension, leading to subsequent diagnosis of primary aldosteronism.3
In a study conducted by Yu-Yao Huang et al for primary aldosteronism, 21 patients presented with muscular paralysis as the initial symptom, with seven patients having extralimb muscle involvement and six patients presenting with bulbar palsy.3
Gangal et al reported sudden onset of flaccid quadriparesis with severe hyopokalaemia in their patient who was a known case of hypertension on thiazide therapy. Following potassium supplementation his quadriparesis reversed.4 In a case report by SM Winship, the patient was a known hypertensive on tablet atenolol, had undergone coronary artery bypass grafting, suddenly presented with dizziness and postural hypotension with potassium levels of 2.7 mmol/L.2
Our patient presented with generalized muscle weakness as the initial symptom, followed by sudden onset quadriplegia which was reversed following potassium supplementation.
These patients often present with spontaneous hypokalaemia (serum potassium < 3.5 mEq/L) and difficulty in maintaining normal serum potassium levels despite the concomitant use of oral potassium supplements, with refractory hypertension, accompanied by few or no cardiovascular complications. The loss of potassium causes a marked decrease in plasma concentration. Since 98% of body potassium is located intracellularly, large potassium deficits are present in a patient with chronically low serum potassium levels.
This patient had spontaneous hypokalaemia (serum potassium 1.5 mEq/L), but maintained normal serum potassium levels during subsequent treatment with spironolactone.
Chronic potassium depletion per se, may result in a particular form of cardiomyopathy, with the disruption of microfilaments and ballooning of cell membranes. Aldosterone is emerging as a key player in the cause of heart failure. Aldosterone has two direct effects on heart. It potentiates the effect of catecholamines, probably by blocking noradrenline reuptake and it predisposes to myocardial fibrosis.6
Our patient’s hypertension was controlled on tablet carvedilol 3.25 mg with 2-D echocardiography showing diffuse hypokinesia with ejection fraction of 42%. Often, plasma aldosterone levels and plasma renin activity (PRA) are measured as initial screening tests and dexamethasone suppression test performed to exclude the rarer, dexamethasone suppression aldosteronism.2 The single best test suggested for identification of patients with primary aldosteronism is the measurement of aldosterone excretion rate (AER) during salt loading (25 ml/kg of normal saline iv over 4 hours for 3 days). A rate greater than 14 mg/ 24 hours following 3 days of salt loading distinguishes most patients with primary aldosteronism from those with essential hypertension.5 More invasive investigations include adrenal vein sampling for aldosterone and CT or MRI scanning which may reveal the presence of tumour.2
In our case however only CT scan of abdomen was done, which suggested adenoma from left adrenal gland.
Unilateral or bilateral adrenalectomy may be performed depending on the pathology. In keeping with other forms of surgery, the laparoscopic approach is used increasingly. Both laparoscopic and open approaches may be performed with patient supine. However the lateral approach reduces the need for surgical traction and results in an improved view by allowing blood to drain away from surgical field?
In our case, laparoscopic adrenalectomy was performed in the right lateral position.
Most anaesthetic problems are related to hypertension and potassium depletion. Antihypertensive drugs might have interaction with the anaesthetic agents used, resulting in bradyarrhythmia and hypotension. Hypokalaemia and metabolic alkalosis can theoretically prolong the action of non-depolarizing neuromuscular blocking agents.
In Finch’s view of sixty patients undergoing adrenal exploration for primary hyperaldosteronism, a variety of anaesthetic techniques, including thiopentone, halothane and ether appear to have been well tolerated.8
In the case report by Y Gangat et al, a patient with primary aldosteronism developed tonic muscular contracture of arms, shoulders, neck and anterior chest wall, following induction with injection thiopental 2.5%. This has been attributed to the altered balance of cortical and spinal inhibitory and facilitatory pathways influence on motor neurons which facilitates increased muscle excitability due to potassium derangement.4
In our case, induction was with injection propofol and was smooth without any alterations.
Shipton and Hugo noted that during the first post operative week a negative balance of sodium and potassium occurs. Replacement mineralocorticoid therapy is required for those patients undergoing bilateral adrenalectomy and occasionally temporarily for those patients undergoing unilateral adrenalectomy.2
This patient had his serum potassium levels within the normal range postoperatively and was maintained only on tablet carvedilol 3.25 mg once a day.
The surgical cure rate for hyperaldosteronism may be as high as 60-77%, though it may take a year or more for hypertension to resolve. The best response to surgical treatment appears to be associated with - presence of adenoma, age younger than 44 years, duration of hypertension less than 5 years and positive pre-operative response to spironolactone.10
Patient with Conn’s syndrome pose a challenge to anaesthesiologist with potassium and haemodynamic monitoring being the key to successful management.
References
- Conn JW. Primary aldosteronism, a new clinical syndrome. J Lab Clinical Medicine 1955; 45 : 3-17.
- Winship SM, Winstanley JH. Case report : Anaesthesia for Conn’s syndrome. Anaesthesia 1999; 54 : 564-74.
- Yu-Yao Huang, Brend-Ray Shea Hsll, et al. Paralytic myopathy - a leading clinical presentation for primary aldosteronism in Taiwan. Journal Clinical Endocrinology and Metabolism 1996; 81 : 4038-44.
- Gangat Y, Turner L, et al. Clinical reports : Primary aldosteronism with uncommon complications. Anaesthesiology 1976; 45 (5) : 542-44.
- Bravo EL. Clinical aspects of endocrine hypertension. Medical Clinics of North Amercia 1987; 71 : 907-19.
- Struthers AD. Aldosterone escape during ACE inhibitor therapy in chronic heart-failure. European Heart Journal 1995; 16 : 103-6.
- Fletcher DR, Beiles CB, Hardy KJ. Laparoscopic adrenalectomy Australia and New Zeland. Journal Surgery 1994; 64 : 427-30.
- Finch JS. Primary aldosteronism : Review of the anaesthetic experience in sixty patients. British Journal Anaesthesia 1969; 41 : 880-3.
- Shipton EA, Hugo JM. Primary aldosteronism and its importance to anaesthetist. South African Medical Journal 1982; 62 : 60-3.
- Gleno, O’Brien, Mellay JC, Beazley RM. Factors influencing outcome of surgery for primary aldosteronism. Archives of Surgery 1996; 131 : 646-50.
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