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Metabolic disorders 

Metabolic disorders
Chapter:
Metabolic disorders
Author(s):

Heather Baid

, Fiona Creed

, and Jessica Hargreaves

DOI:
10.1093/med/9780198701071.003.0012
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date: 09 May 2021

Diabetes mellitus

Definition

Diabetes mellitus is a chronic disease characterized by raised blood glucose levels. The disease has several different subtypes:

  • Type 1 diabetes—thought to be related to autoimmune destruction of the beta cells in the pancreas. It commonly occurs in childhood or young adulthood, and patients require insulin replacement therapy.

  • Type 2 diabetes—the most common form of diabetes. The World Health Organization predicts that there will be a doubling in the number of people with type 2 diabetes by 2030. It normally occurs as a result of the development of insulin resistance and a reduction in the ability of the pancreas to produce sufficient insulin. It may be controlled by dietary modification, oral hypoglycaemic medication, or insulin, depending on the severity of the disease. The increasing number of patients with type 2 diabetes in developed countries is thought to be due to lifestyle factors such as poor diet and obesity.

  • Gestational diabetes—this can occur as a result of pregnancy, and the patient’s health status may return to normal after delivery, or gestational diabetes may precede the development of type 2 diabetes.

Patients with diabetes may be admitted to critical care because of poor glucose control, which may be caused by:

  • diabetic ketoacidosis

  • hyperglycaemic hyperosmolar states

  • hypoglycaemia.

Diabetic ketoacidosis

Definition

Diabetic ketoacidosis (DKA) is a complex metabolic disorder characterized by the presence of:

  • hyperglycaemia

  • acidosis

  • ketonaemia.

It is more likely to occur in patients with type 1 diabetes, but is increasingly being seen in patients with type 2 diabetes. The incidence is approximately 4–8 episodes per 1000 members of the population of patients with diabetes. Mortality rates have fallen significantly over the past two decades, and represent about 2% of all cases.

Assessment findings

The patient should be assessed using a systematic framework such as ABCDE (see Metabolic disorders p. [link]) to evaluate the effect of DKA on the body’s systems. Patients who present in critical care with DKA are likely to have a combination of the following symptoms on admission:

  • blood ketone level > 6 mmol/L

  • bicarbonate level < 5 mmol/L

  • arterial pH < 7.0

  • decreased GCS score (< 12)

  • reduced oxygen saturations

  • hypotension secondary to hypovolaemia (excessive diuresis)

  • tachycardia

  • anion gap > 16 mmol/L.

Management

Management should follow a recognized care bundle. The Joint British Diabetes Societies Inpatient Care Group1 recommends that care bundles are split into four time zones in the first 24-h period:

  • hour 1—immediate management

  • 1–6 hours

  • 6–12 hours

  • 12–24 hours.

Management is based on:

  • stabilization

  • restoration of adequate circulation

  • glucose control

  • electrolyte replacement.

Stabilization

The patient’s ability to maintain an airway should be assessed. If the patient’s GCS score is low, intubation and mechanical ventilation are likely to be needed.

  • Self-ventilating patients will require oxygen to maintain normal saturations.

  • Frequent ABG measurements should be recorded to monitor O2, CO2, and pH levels.

Restoration of adequate circulation

  • Water deficits are likely to be high (estimated at 100 mL deficit/kg).

  • Significant fluid replacement may be required.

  • Crystalloid fluid replacement is recommended. Current guidelines suggest 0.9 % saline with added premixed KCl. Care should be taken to monitor for hyperchloraemia.

  • Rapid fluid replacement with care is recommended for adults. Rapid fluid replacement is not recommended for children and small young adults. Table 12.1 shows the suggested rates for a previously well 70 kg adult.1

  • Target blood pressure is normally a systolic pressure of > 90 mmHg.

  • CVS monitoring and invasive fluid assessment (e.g. CVP) may be required.

  • Fluid balance should be closely monitored. The patient will require urinary catheterization.

  • Patients with a history of CVS, renal impairment, or comorbidities will require extra vigilance during the assessment of fluid status.

Table 12.1 Saline and potassium replacement regime1

Fluid

Volume

0.9% sodium chloride

1000 mL over first hour

0.9% sodium chloride with potassium chloride

1000 mL over next 2 h

0.9% sodium chloride with potassium chloride

1000 mL over next 2 h

0.9% sodium chloride with potassium chloride

1000 mL over next 4 h

0.9% sodium chloride with potassium chloride

1000 mL over next 4 h

0.9% sodium chloride with potassium chloride

1000 mL over next 6 h

Reassessment of CVS status is mandatory at 12 h. Further fluid may be required

Glucose control

  • A fixed-rate IV insulin infusion (FRIII) should be commenced, and this should be related to weight, with the exception of obese patients, for whom a modified scale is recommended.

  • Give an insulin infusion of 50 units of soluble insulin in 50 mL of 0.9% saline.

  • Current guidelines suggest that a fixed rate of 0.1 unit of insulin/ kg/h should be infused (e.g. 7 mL/h). Suggested weight-related infusion rates are shown in Table 12.2.1

  • Regular blood glucose monitoring is essential.

  • If the blood glucose concentration is > 20 mmol/L or ‘high’ on point-of-care testing (POCT), specimens should be sent to the main laboratory.

  • The blood glucose concentration should decrease by 3 mmol/h. Failure to achieve this target requires urgent review.

  • If the glucose concentration falls below 14 mmol/L in the first 6 h, IV glucose may be required.

  • Blood ketones should be assessed regularly. If this is not possible, venous bicarbonate levels may be assessed. Ketone monitoring should be continued until ketoacidosis has been corrected.

  • If the patient takes long-acting insulin this may still be administered subcutaneously if the local protocol permits.

  • FRIII should be discontinued once the patient is stable. Normal medication administration should then be commenced following discussion with the medical team.

Table 12.2 Weight-related doses for fixed-rate IV insulin infusion (FRIII)

Patient weight (kg)

Insulin dose (units/h)

60–69

6

70–79

7

80–89

8

90–99

9

100–109

10

110–119

11

120–129

12

130–139

13

140–149

14

> 150

15 (refer to diabetic team)

Electrolyte replacement

  • Administration of IV insulin will reduce serum potassium levels. Therefore close observation is needed.

  • The recommended target range for potassium levels is 4–5 mmol/L.

  • Potassium replacement should be given as standard (see Table 12.1). If potassium levels are outside the normal reference range (high or low), medical review should be urgently sought.

  • Monitor for signs of cardiac arrhythmias linked to potassium abnormalities.

  • There is no evidence to support the routine use of sodium bicarbonate or phosphate administration.

  • Regular assessment of other electrolytes is recommended, and treatment in line with normal local protocols.

Complications associated with DKA

Several complications may arise following the management of DKA. These include the following:

  • Hypokalaemia and hyperkalaemia—these are potentially life-threatening. Careful management during the acute episode should prevent them from occurring.

  • Hypoglycaemia—severe hypoglycaemia is associated with cardiac arrhythmias, acute brain injury, and death. Care should be taken to closely monitor blood glucose levels, and replacement glucose should be provided once the blood glucose concentration falls to 14 mmol/L and FRIII is continuing. Close monitoring for signs of hypoglycaemia is essential. Note that signs will be masked in the sedated ventilated patient.

  • Cerebral oedema—this is uncommon in adults with DKA. Children are more likely to develop cerebral oedema, and therefore separate guidance is available for the management of DKA in children.

  • Pulmonary oedema—this is unlikely to occur, and if it does may be linked to iatrogenic fluid overload. Care should be taken with fluid replacement in vulnerable groups (i.e. patients with cardiac or renal impairment, or comorbidities). Additional monitoring and assessment may be required in these patient groups.

Reference

1 Joint British Diabetes Societies Inpatient Care Group. The Management of Diabetic Ketoacidosis in Adults. Diabetes UK: London, 2013.Find this resource:

Hyperglycaemic hyperosmolar state

Definition

There is not a universally accepted definition of hyperglycaemic hyperosmolar state (HHS), and it is argued that any such definition would be an arbitrary one. Nevertheless, this is a specific problem associated with diabetes that requires specific management. It is more common in elderly patients with type 2 diabetes, but may also be seen in younger patients. The mortality rate is significantly higher, at around 15–25% of patients who present with HHS. The condition tends to manifest over a period of days (unlike DKA), resulting in severe dehydration and hyperosmolar states. Other respects in which HHS differs from DKA include:

  • high osmolarity

  • hyperglycaemia without severe ketoacidosis

  • severe dehydration

  • an extremely unwell patient.

Assessment

The patient should be assessed using a systematic framework such as ABCDE (see Metabolic disorders p. [link]) to evaluate the effect of HHS on the body’s systems. Patients who are admitted to level 2 or 3 care tend to present with:

  • serum osmolality > 350 mOsm/L

  • serum sodium concentration > 160 mmol/L

  • pH < 7.0

  • hypo- or hyperkalaemia

  • deteriorating GCS score or cognitive impairment

  • reduced oxygen saturations

  • low blood pressure

  • tachycardia or bradycardia

  • oliguria

  • serum creatinine concentration > 200 μ‎mol/L

  • hypothermia

  • other serious comorbidities.

Management

Management should follow a recognized care bundle. The Joint British Diabetes Societies Inpatient Care Group2 recommends that care bundles are divided into four time zones in the first 24-h period:

  • hour 1—immediate management

  • 1–6 h

  • 6–12 h

  • 12–24 h.

The goals of treatment are to:

  • stabilize the patient

  • normalize serum osmolality

  • restore circulating volume

  • normalize blood glucose levels

  • restore electrolyte balance.

Stabilization

The patient’s ability to maintain an airway should be assessed. If the patients’s GCS score is low, intubation and mechanical ventilation are likely to be needed.

  • Self-ventilating patients will require oxygen to maintain normal saturations.

  • Frequent ABG measurements should be recorded to monitor O2, CO2, and pH levels.

Normalization of serum osmolality

  • Patients will present with extreme fluid loss It is estimated that HHS causes fluid depletion in the range of 100–220 mL/kg.

  • Serum osmolality requires close monitoring and should be measured hourly. (If POCT is not available, this may require calculation using the following formula: serum osmolality = 2Na+ + glucose + urea.) It may be useful to plot the results graphically to see the trend in levels.

  • Rapid changes in osmolality may be harmful because rapid correction of osmolality may cause significant fluid shifts, so fluid replacement should be performed cautiously to provide a gradual decline in serum osmolality.

Restoration of circulating volume

  • Cautious fluid replacement is required to prevent significant fluid shifts and complications of HHS.

  • Current recommendations are that 0.9% sodium chloride should be used as principal fluid replacement. If the patient’s osmolality is not falling despite fluid replacement, hypotonic solutions such as 0.45% sodium chloride may be used.

  • The aim of treatment is to replace approximately 50% of volume lost in the first 12 h, and the remainder in the following 12 h.

  • The suggested fluid regime is 1 L of 0.9% sodium chloride in the first hour, followed by 0.5–1 L/h in the next 6 h. The target is to achieve a positive balance of 2–3 L within 6 h.

  • Care should be taken with vulnerable groups (i.e. patients with cardiac or renal impairment, and those with comorbidities).

Normalization of blood glucose levels

  • Fluid replacement alone will reduce blood glucose levels as serum osmolality decreases during the initial stages.

  • Care should be taken to ensure that insulin therapy is commenced after initial fluid resuscitation, to avoid fluid shifts to the intracellular space.

  • Insulin may be required earlier in the management of the patient if they have significant ketonaemia.

  • If insulin is required, a fixed-rate IV insulin infusion (FRIII) should be started at 0.05 units/kg/h (e.g. 4 units in an 80 kg patient).

  • The aim is to reduce blood glucose levels slowly, at a rate of 5 mmol/L/h.

  • Higher doses of insulin may be required if the initial doses of insulin and fluid do not decrease blood glucose levels.

Restoration of electrolyte balance

  • Sodium and potassium levels should be closely monitored.

  • Sodium levels may increase slightly during initial fluid resuscitation.

  • Further fluid resuscitation may be required if sodium levels continue to rise.

  • Sodium levels should not be decreased too quickly. The decrease should not exceed 10 mmol in 24 h.

  • Potassium shifts are less pronounced than in DKA.

  • Potassium levels should be monitored and potassium replaced if necessary.

  • Hypophosphataemia and hypomagnesaemia are common in HHS.

  • There is little evidence to support replacement of phosphate and magnesium unless this is clinically indicated.

Complications of HHS

Complications are associated with a higher mortality rate in this group of patients. They include:

  • vascular complications:

    • myocardial infarction

    • stroke

    • venous thromboembolism

  • seizures

  • cerebral oedema

  • central pontine myelinolysis.

The cerebral complications are normally associated with a rapid shift in osmolality levels. Therefore it is important to correct osmolality carefully and gradually.

Reference

2 Joint British Diabetes Societies Inpatient Care Group. Management of the Hyperosmolar Hyperglycaemic State (HHS) in Adults with Diabetes. Diabetes UK: London, 2013.Find this resource:

Hypoglycaemia

Definition

Hypoglycaemia is the commonest side effect of insulin and sulfonylurea medications. Other treatments for diabetes are less likely to cause hypoglycaemia. Hypoglycaemia may be defined as a blood glucose concentration below 4 mmol/L.

Risk factors for critically ill patients developing hypoglycaemia include:

  • tight glycaemic control

  • severe liver failure

  • renal replacement therapy

  • reduction in feeding or carbohydrate intake

  • Addison’s disease

  • hypo- and hyperthyroidism

  • misreading the patient’s prescription, or medication error

  • inadequate blood glucose monitoring.

Assessment

Common signs of hypoglycaemia may be masked in the sedated and ventilated critically ill patient. The patient should be assessed using a systematic framework such as ABCDE (see Metabolic disorders p. [link]) to evaluate the effect of hypoglycaemia on the body’s systems. Symptoms include the following:

Autonomic signs

  • Sweating.

  • Palpitations.

  • Shaking.

  • Hunger.

Neuroglycopenic signs

  • Confusion.

  • Drowsiness.

  • Odd behaviour.

  • Speech difficulty.

  • Incoordination.

General malaise

  • Headache.

  • Nausea.

In addition, hypoglycaemia can cause:

  • coma

  • hemiparesis

  • seizures

  • permanent neurological deficits

  • death.

Management

Prompt management is essential to prevent neurological damage. An ABCDE assessment (see Metabolic disorders p. [link]) will identify the priorities of care. The patient may require high-flow oxygen or increased oxygen during the hypoglycaemic episode. Management includes the following:

  • immediate cessation of any IV insulin until the patient has stabilized

  • increasing blood glucose levels (the three options are shown in Table 12.3)

  • reassessment and close monitoring of blood glucose levels following a hypoglycaemic episode

  • checking blood glucose levels more regularly following a hypoglycaemic episode

  • establishing whether there was a reason why hypoglycaemia occurred.

Table 12.3 Methods of increasing blood glucose levels

Drug

Method of administration

Glucagon

  • Useful for patients without IV access

  • May take up to 15 min to work

  • Mobilizes glycogen from the liver

  • Less effective if patient is taking sulfonylurea, or if patient has liver failure or chronic malnutrition

20% or 10% glucose

  • 75–85 mL over 10–15 min (20%)

  • 150–160 mL over 10–15 min (10%)

  • Given intravenously

  • Rapid response

  • Blood glucose levels should be checked after 10 min

  • Repeated doses may be required

  • Extravasion may cause tissue damage

  • Central access is preferred route

  • May be given peripherally in an emergency (unlicensed route)

  • May cause pain or phlebitis if given peripherally

  • May cause rebound hyperglycaemia

Further reading

Joint British Diabetes Societies Inpatient Care Group. The Hospital Management of Hypoglycaemia in Adults with Diabetes Mellitus. Diabetes UK: London, 2013.Find this resource:

Diabetes insipidus

Definition

Diabetes insipidus (DI) is caused by insufficient secretion of antidiuretic hormone (ADH). In the absence of ADH the kidneys secrete too much water, leading to significant fluid loss and hypovolaemia. High sodium levels are caused by the removal of excessive water, and serum osmolality will rapidly increase. DI can be triggered by nephrogenic or neurogenic causes. It may also be triggered by pregnancy (gestational DI).

Nephrogenic DI causes the kidneys to fail to respond to the presence of ADH. It can be triggered by:

  • genetic disorders

  • renal diseases:

    • pyelonephritis

    • post transplantation

  • systemic diseases:

    • sickle-cell anaemia

    • polycystic disease

  • medication side effects:

    • lithium

    • gentamycin.

Neurogenic or central DI may be triggered by:

  • cerebral oedema following traumatic brain injury

  • damage to the pituitary gland (e.g. due to trauma, surgery, or stroke)

  • tumours of the posterior pituitary gland, or removal of tumours of the pituitary gland.

Assessment

The patient should be assessed using a systematic framework such as ABCDE (see Metabolic disorders p. [link]) to evaluate the effect of hypoglycaemia on the body’s systems. Symptoms include:

  • polyuria

  • polydipsia (if the patient is conscious)

  • signs of dehydration

  • hypotension

  • tachycardia

  • increased capillary refill time

  • decreased CVP.

Laboratory results may show:

  • reduced levels of ADH

  • high sodium levels

  • high serum osmolality

  • low urine osmolality

  • low urinary specific gravity.

Management

Management is linked to:

  • prevention of dehydration

  • correction of sodium imbalance

  • prevention of further complications.

Nursing and medical management

  • Careful recording of fluid intake and output is essential.

  • Accurate fluid balance is needed to enable calculation of likely fluid requirements. The free water (FW) deficit may be calculated using the following formula:

    FW deficit = 0.6 × weight (kg) × (current Na ÷ 14 1).

  • Regular cardiovascular assessment is needed to determine the effect of fluid loss on cardiac output.

  • Fluid replacement is needed to prevent dehydration and hypovolaemic shock. Significant fluid replacement may be required if diuresis is excessive. Fluid replacement will be guided by blood results and the patient’s condition.

  • Neurogenic DI (central DI) responds well to administration of vasopressin, and this should be given as required to reduce urine output.

  • Nephrogenic DI will not respond to vasopressin, and may require the use of thiazide diuretics to attempt to regulate water and sodium excretion.

  • A rapid return to normal osmolality may cause worsening of cerebral oedema in patients with traumatic brain injury, and care should be taken to closely monitor serum osmolality.

Complications of DI

  • Cardiovascular compromise.

  • Seizures.

  • Encephalopathy.

Further reading

Morton PG and Fontaine DK. Essentials of Critical Care Nursing: a holistic approach. Lippincott Williams & Wilkins: Philadelphia, PA, 2013.Find this resource:

Hyperthyroidism

Definition

Hyperthyroidism is a medical condition caused by excessive levels of thyroid hormones. Graves’ disease is the most common form of hyperthyroidism. Over-secretion of thyroid hormones leads to increased cellular metabolism throughout the body, and symptoms may include:

  • weight loss

  • tachycardia

  • hyperactivity

  • fatigue

  • gastrointestinal hypermotility

  • muscle tremor

  • anxiety

  • exophthalmos.

A rare but life-threatening form of hyperthyroidism is thyrotoxicosis (sometimes referred to as a thyroid storm). Thyrotoxicosis normally occurs in untreated or undertreated patients with hyperthyroidism. It may be triggered by:

  • severe infection

  • pregnancy

  • trauma

  • withdrawal or non-compliance with anti-thyroid medication

  • iodine therapy.

Assessment

The patient should be assessed using a systematic framework such as ABCDE (see Metabolic disorders p. [link]) to evaluate the effect of hormone excess on the body’s systems. Symptoms include:

  • pyrexia (often > 40°C)

  • tachycardia

  • arrhythmias

  • hypertension

  • hypotension

  • cardiac failure

  • fluctuations in consciousness (agitation, confusion, or coma)

  • seizures

  • diarrhoea, vomiting, and abdominal pain

  • unexplained jaundice.

Management

Management of the patient should focus on four main areas:

  • supportive therapy

  • reduction of plasma thyroid concentration

  • blockade of the peripheral effects of thyroxine

  • isolation of causative factors.

It is usual to measure thyroid-stimulating hormone, and free and total T3 and T4.

  • Airway and breathing assessment is needed to determine the adequacy of ventilation and oxygenation.

  • Oxygen should be administered in self-ventilating patients to maintain normal saturations (above 94%).

  • Cardiovascular assessment is needed to determine the effects of excessive thyroxine on the cardiovascular status.

  • Continuous monitoring is needed to identify and allow prompt management of cardiac arrhythmias.

  • Anti-arrhythmic medication may be required.

  • Blood pressure and cardiac output should be monitored and heart failure treated if necessary.

  • Temperature regulation should be monitored and appropriate action taken to treat hyperpyrexia.

  • Sedation may be required if the patient is excessively agitated. However, care should be taken that the sedative medication does not suppress respiratory function.

Medical management

Various medical regimes may be used to control acute episodes. Treatment is aimed at blocking the synthesis, release, and conversion of thyroxine and reducing the effects of thyroxine on the cardiovascular system. This is achieved as follows:

  • Anti-thyroid medication to prevent the synthesis of thyroxine will normally be administered.

  • Iodine to inhibit the release of thyroxine may also be administered.

  • Beta blockade is used to inhibit the peripheral effects of excessive thyroxine and reduce stress on the cardiovascular system.

  • Steroids may also be administered to inhibit the conversion of T3 to T4. Hydrocortisone or dexamethasone may be used.

A final consideration is the isolation and management of the cause.

  • If infection is likely, appropriate antimicrobial treatment should be commenced.

  • Trauma or other suspected contributing factors should be managed accordingly.

Further reading

Carroll R and Matfin G. Endocrine and metabolic emergencies: thyroid storm. Therapeutic Advances in Endocrinology and Metabolism 2010; 1: 139–45.Find this resource:

Hypothyroidism

Definition

Hypothyroidism or myxoedema is a medical condition caused by decreased levels of thyroid hormones—T3 (liothyronine sodium) and T4 (thyroxine sodium). Patients with hypothyroidism present in hospital with symptoms related to under-secretion of hormones. These may include:

  • bradycardia

  • hypotension

  • fatigue

  • oedema

  • increased weight.

Myxoedema coma is a rare but life-threatening condition linked to decreased thyroid function. This group of patients will normally require critical care management. Myxoedema coma occurs in patients with hypothyroidism, and may be triggered by:

  • infection

  • stroke

  • trauma

  • gastrointestinal bleeds

  • use of some sedatives.

It may also be triggered in critically ill patients if their maintenance dose of thyroxine is omitted. Patients may also present in an acute coma with previously undiagnosed hypothyroidism.

Assessment

The patient should be assessed using a systematic framework such as ABCDE (see Metabolic disorders p. [link]) to evaluate the effect of hormone deficiency on the body’s systems. Symptoms include:

  • decreased level of consciousness

  • seizures

  • hypoxia and hypercapnia secondary to hypoventilation

  • hypotension

  • bradycardia

  • heart blocks and arrhythmias

  • fluid retention

  • hyponatraemia

  • decreased gut motility

  • nausea, vomiting, and constipation

  • hypothermia

  • hypoglycaemia.

Management

Immediate stabilization of the patient presenting with myxoedema coma is essential alongside drug therapy to correct decreased thyroxine levels.

  • Airway assessment is required, as decreased level of consciousness may necessitate intubation.

  • Ventilation or respiratory support may be required to maintain adequate gaseous exchange.

  • Acid–base balance should be monitored with ABG sampling.

  • Thorough assessment of cardiovascular status is required to monitor the effects of electrolyte imbalance on the cardiovascular system.

  • Continuous cardiac monitoring will be required, especially if the patient has severe bradycardia or heart block.

  • Fluid balance should be monitored and fluid and electrolytes replaced accordingly. Cautious fluid replacement may be used to maintain diuresis.

  • Care should be taken not to increase sodium imbalance too quickly because of the risk of central pontine myelinolysis (damage to the myelin sheath of neurons in the brainstem). This may cause life-threatening neurological disturbances such as unconsciousness, seizures, and cessation of respiratory function.

  • Blood glucose monitoring and supplementation of glucose may be required (see Metabolic disorders p. [link]).

  • Central temperature should be monitored, as the patient may require gradual rewarming.

  • Neurological status should be closely monitored. Seizures should be monitored and treated accordingly.

  • The cause of the crisis should be identified and treated.

  • Drug therapy (i.e. thyroxine replacement) will be required. This should be administered either orally or intravenously, depending on the patient’s condition. Thyroxine levels should be monitored carefully. A sudden increase in thyroxine levels may cause angina, arrhythmias, and myocardial infarction, so should be avoided.

Further reading

Mathew V et al. Myxedema coma: a new look into an old crisis. Journal of Thyroid Research 2011; 2011: 493462.Find this resource:

Phaeochromocytoma

Definition

A phaeochromocytoma is a rare endocrine tumour of the chromaffin cells that causes excessive secretion of catecholamines and is associated with signs and symptoms of catecholamine excess. Patients with phaeochromocytoma may be admitted to critical care units because of:

  • a hypertensive crisis triggered by the tumour

  • the need for pre-optimization before surgery (specialist centre)

  • post-operatively, following excision of tumour (specialist centre).

Assessment

Signs and symptoms are related to excessive amounts of circulating catecholamines. Patients may present with:

  • palpitations or tachycardia

  • headache

  • sweating

  • severe hypertension (sustained or paroxysmal)

  • nausea and other abdominal symptoms

  • chest pain

  • hyperglycaemia.

Diagnosis is based on a number of assessment tools, including:

  • measurement of urinary and serum metanephrines (formed by the breakdown of catecholamines); this may not be useful in critical care patients

  • CT scan

  • MRI

  • PET scan.

Management

Initial management may be medical in nature and focus on stabilization of the patient if a hypertensive crisis occurs. It is likely that short-acting antihypertensive medication will be administered in a hypertensive crisis.

Management of hypertension

Patients in a hypertensive crisis will require:

  • constant cardiovascular monitoring

  • administration of short-acting antihypertensive medication

  • careful titration of medication to prevent significant swings in blood pressure.

Surgery is usually the main treatment for this tumour, and may be performed laparoscopically. Management may relate to pre-operative and post-operative considerations.

Pre-operative considerations

Surgery may cause a massive release of catecholamines, and it is usual practice to attempt to reduce the problems associated with surgery by adequate pre-operative preparation. This may involve the following:

  • Thorough cardiovascular assessment (echocardiogram, blood pressure measurement, ECG, etc.). Pre-existing cardiac disease will be adversely affected by sudden release of catecholamines.

  • Administration of alpha blockade to minimize the risk of an intra-operative hypertensive crisis. Calcium-channel blockers may also be used.

  • Low-dose beta blockade may also be administered to minimize the potential tachycardia reflex response.

  • An acute pre-operative hypertensive crisis may be managed with short-acting antihypertensive medication such as nitroprusside or magnesium sulphate.

Post-operative considerations

Surgery can potentially cause the patient to become unstable, and blood pressure instability and tachycardia are common, as is hypoglycaemia. Removal of the tumour may precipitate marked vasodilatation that may not respond to vasopressors because of pre-operative alpha blockade which persists for more than 36 h. Patients may require:

  • constant cardiovascular monitoring

  • fluid resuscitation to maintain blood pressure

  • monitoring of blood glucose levels (due to rebound hypoglycaemia)

  • monitoring for a potential Addisonian crisis (in patients with hypotension and hypoglycaemia)

  • hypertension can occur, and the underlying cause should be determined and treated (e.g. pain, autonomic instability, volume overload).

Further reading

Därr R et al. Pheochromocytoma—update on disease management. Therapeutic Advances in Endocrinology and Metabolism 2012; 3: 11–26.Find this resource:

Addison’s disease

Definition

Addison’s disease is a relatively rare disorder caused by primary adrenal cortisol insufficiency. It usually occurs as a result of autoimmune destruction of the adrenal cortex, but may also be triggered by cancers, tuberculosis, infection, and as a side effect of some medications (e.g. ketoconazole). In addition, it may occur secondary to hypothyroidism, surgical removal of the pituitary gland, or a sudden withdrawal from high-dose glucocorticoid therapy.

Assessment

Signs and symptoms are related to the decreasing levels of glucocorticoids and mineralocorticoids. Two of the primary roles of these hormones are to help to regulate fluid and electrolyte balance and blood glucose levels.

Acute development of adrenal cortisol insufficiency can trigger an Addisonian crisis (a life-threatening condition which may manifest with little warning). This may follow severe infection, trauma, or major surgery where the demand for cortisol and aldosterone exceeds supply.

The patient will quickly deteriorate and cardiovascular collapse will occur if prompt management is not instigated. The patient should be assessed using a systematic framework such as ABCDE (see Metabolic disorders p. [link]) to evaluate the effect of hormone deficiency on the body’s systems. Symptoms include:

  • fluid and electrolyte loss

  • hypovolaemia

  • hyponatraemia

  • hypoglycaemia

  • hyperkalaemia

  • hypercalcaemia

  • leukocytosis

  • possible acidosis

  • possible abdominal pain, nausea, and vomiting.

Management

Immediate management of an Addisonian crisis is necessary to ensure that essential metabolic function is maintained. Crawford and Harris3 have highlighted the need to target the 5 S’s:

  • salt replacement

  • sugar replacement

  • steroid replacement

  • support of physiological functions

  • search for the causative factor.

This will necessitate the following:

  • thorough assessment of the patient’s cardiovascular status to monitor for the effects of fluid loss and electrolyte imbalance of the cardiovascular system

  • rapid fluid replacement using crystalloids; inotropic support may be required if cardiovascular compromise is severe

  • continuous ECG monitoring because of hyperkalaemia

  • correction of hyperkalaemia using insulin and dextrose to prevent cardiac arrhythmias

  • strict fluid balance to note fluid losses and replacement

  • strict blood glucose monitoring, and replacement of glucose if serum blood glucose levels are low (see Metabolic disorders p. [link])

  • administration of hydrocortisone (immediate drug therapy) and fludrocortisone (once the patient is stable) (see Box 12.1)

  • investigations to identify and rectify the possible cause

  • vigilance for signs of infection (linked to immunosuppression by IV steroids).

Reference

3 Crawford A and Harris H. Adrenal cortex disorders: hormones out of kilter. Nursing 2011 Critical Care 2011; 7: 20–35.Find this resource: