Adrenal medullary disease i.e. adrenal pheochromocytoma or hyperplasia, secreting catecholamines. Pathophysiology: It mainly secretes large amounts of adrenaline and norepinephrine. Clinical symptoms include hypertension, cardiac arrhythmias and metabolic abnormalities. The disease may occur in the liver, gallbladder, mesentery, and bladder, in addition to the adrenal medulla.
He Hongqi, Department of Anesthesiology, Rongchang County People’s Hospital, Chongqing, China1 Clinical symptoms
(1) Hypertension Mainly large amounts of catecholamines lead to strong constriction of peripheral blood vessels and episodic or paroxysmal or persistent hypertension.
(2) Typical patients may have the triad of heart quarter, headache and sweating at the same time, and may also have symptoms such as dizziness, nervousness, pallor and weakness.
(3) Long-term hypercatecholaminesemia can lead to catecholamine-induced cardiomyopathy [mainly caused by coronary artery constriction and increased myocardial oxygen consumption], which manifests as arrhythmia and myocardial strain, and the electrocardiogram shows predominantly left ventricular hypertrophy with strain. In severe cases, this may lead to heart failure and myocardial infarction.
(4) Some patients may also have significant cardiovascular, cerebral, and renal vascular complications and visual disturbances, as well as electrolyte disturbances.
(5) Clinically, the diagnosis can be clarified by combining blood and urine catecholamine and its metabolite levels. Blood norepinephrine <3.0~3.5 mol/L, epinephrine <1.8 mol/L, VMA (3 methoxy-4 hydroxy mandelic acid) <35.4 mol/Lv7J/24 hours)
2 Preoperative preparation Purpose: To control symptoms, stabilize intraoperative and postoperative circulation, and reduce complications and mortality.
(1) Preoperative treatment to control hypertension
① α-blockers Control hypertension and reduce cardiac load. Phenobarbital is usually started orally 2~3 weeks before surgery at 80~200J/day. Phenobarbital can be maintained for 3-4 days with one oral dose and gradually increased until the blood pressure is close to normal. The side effects of this drug are mainly bottom blood pressure, tachycardia, etc. At this time, it can be combined with short-acting prazosin.
② β-blockers Most patients do not need to use. It is mainly used in the case of tachycardia and arrhythmia after using α-blockers. It is not necessary to stop the drug prematurely before surgery. Use with caution in cardiac insufficiency.} Channel blockers and pressure ninhydrin and other drugs can be applied together.
As a result of the large amount of catecholamines in pheochromocytoma patients, the peripheral vasculature is strongly constricted and water leaks out of the capillaries, resulting in a rise in intravascular pressure and a decrease in circulating blood volume. Then, the patient is in an overall hypovolemic state. Preoperatively, appropriate volume expansion should be performed along with the application of alpha-blockers, usually starting immediately after anesthesia and supplemented with about 1500 ml of balance fluid or (and) colloid until the intraoperative removal of the tumor, but care should be taken to avoid overloading the heart. If vasodilation and volume expansion are not performed, after tumor removal, due to the drastic reduction of catecholamines supporting the blood vessels, resulting in vasodilation, coupled with the patient’s own hypovolemic state, it is difficult to maintain blood pressure at this time even if drugs such as norepinephrine are applied. In short, pheochromocytoma patients appear to have high blood pressure, but in fact the small blood vessels in the patient’s body are in a state of hypertension, and the patient is actually low in blood volume. Once the substances supporting vasoconstriction are removed or reduced (e.g. after tumor removal), the patient’s blood pressure will drop sharply, at which time dopamine and ephedrine are usually ineffective, and even norepinephrine is not ideal.
(3) Pre-anesthesia medication Sedative drugs must be adequate sedation, anticholinergic drugs are generally used scopolamine. Nowadays, new drugs such as long tonic can also be used.
3 Anesthesia methods
(1) Epidural anesthesia This anesthesia has a certain hypotensive effect on hypertension due to blocking the sympathetic nerve activity in the region, but the blood pressure drops faster after tumor removal. The respiratory management of this anesthesia is inferior to that of general anesthesia, so it is not used or used sparingly.
(2) General anesthesia with tracheal intubation This type of anesthesia is basically used at present. The induction of anesthesia should be smooth, and deeper anesthesia is needed to avoid the strong response to tracheal intubation and induce severe hypertension. Thiopental sodium, etomidate, propofol, lisdexamfetamine, fentanyl, non-depolarizing inotropes such as vecuronium bromide, and carnosine can be used for induction. Bencortisone is not suitable in this disease because it increases the heart rate. Succinylcholine is best not used because it stimulates postganglionic sympathetic neurons and causes myofibrillation, increases abdominal pressure, mechanically squeezes the tumor, and induces catecholamine release. Anflurane, isoflurane and sevoflurane can be used because they do not increase the sensitivity of the myocardium to catecholamines. Desflurane is not used because it stimulates sympathetic nerves and causes an increase in sympathetic activity, leading to instability of the cardiovascular system.
4 Anesthesia management
(1) In addition to the conventional blood pressure, heart rate, SPO2, and end-expiratory CO2 concentration, intraoperative monitoring should include direct arterial pressure measurement and CVP monitoring. Arterial puncture manometry is best performed before induction of anesthesia, so that the dynamic fluctuations of blood pressure can be directly observed during induction and medication can be guided.
(2) Maintenance of circulation
① Before tumor resection, it is usually necessary to lower the blood pressure. It should be equipped with alpha-blocker benzamazoline and sodium nitroprusside. For those with cardiac disorders, nitroglycerin can be used instead of sodium nitroprusside. Blood volume should be replenished while applying drugs. The time to stop the drug is when the tumor blood vessels are blocked. Because after the tumor blood vessels are blocked, a large amount of catecholamines secreted by the tumor cannot enter the blood and cause symptoms, even if the surgeon squeezes the tumor, there is no need to worry. If the drug is discontinued after the tumor is removed, less catecholamines will enter the blood during the period between the blocking of blood vessels and the removal of the tumor. At this time, the blood pressure has already dropped, and with the effect of α-blockers and other drugs, the blood pressure may be further reduced, and if the blood volume is not sufficiently replenished before, the blood pressure may plummet, leading to violent fluctuations in circulation and posing a threat to the patient’s life. α-blockers and sodium nitroprusside are usually pumped by micro-pump after induction of anesthesia, under the monitoring of direct arterial pressure and CVP, and the infusion of fluids is accelerated to replenish the blood volume. (ii) After tumor vascular blockade
② After tumor vascular blockade, due to the decrease of incoming catecholamines → vasodilation, the vascular system volume increases rapidly → blood volume u vascular system volume ratio decreases abruptly → blood pressure drops abruptly. Therefore, in addition to continuing to replenish blood volume, the blood pressure can be maintained with α-agonist norepinephrine. In recent years, we can also use excess fluid according to CVP, so that after blocking the tumor vascular circulation, the blood pressure can be maintained with less use of α-agonists. In addition, β-blockers can be used in combination with high heart rate. The prerequisite is under the condition of blood volume replenishment.
(3) Arrhythmia Due to the increase of catecholamines, tachycardia and ventricular prematureness may result. The first step in the management of this phenomenon is to remove the cause. It is easier and more flexible to control the heart rate with esmolol, an ultra-short-acting beta-blocker. Generally, the heart rate decreases at 0.25 J/K, and at 0.5 J/K it decreases significantly, and at 1 J/K it is accompanied by a decrease in blood pressure. Ventricular premature can be controlled with lidocaine 0.5-1J/K diluted into 20ml line for slow injection, and then 100J IV if necessary.
(4) Application of corticosteroids When the blood pressure cannot be maintained by overhydration and antihypertensive drugs, we should consider the possibility of adrenal insufficiency after tumor removal, and corticosteroids should be supplemented at this time. Generally, hydrocortisone 200J should be used as an intravenous drip.
(5) High metabolism, hyperglycemia Due to the large amount of catecholamines into blood, it causes high metabolism and hyperglycemia. However, when the tumor is removed, hypoglycemia may occur due to the sudden decrease of hormonal effect. Patients may have excessive sweating, stagnant peripheral circulation and decreased blood pressure. If the conventional management is not good, glucose injection may improve.