Rhabdomyolysis
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1- Introduction
2- Pathophysiology
3- Causes
4- Treatment
Introduction
Rhabdomyolysis is a medical condition characterized by the breakdown of skeletal muscle tissue, leading to the release of muscle fibers and their contents into the bloodstream. This release can result in harmful substances, such as myoglobin, being released into the bloodstream and potentially causing kidney damage. Common causes include trauma, strenuous exercise, medications, infections, and certain metabolic disorders. Symptoms may include muscle pain, weakness, dark urine (due to myoglobinuria), and in severe cases, kidney failure.
Pathophysiology
Fluid Resuscitation: Adequate hydration is crucial to help flush myoglobin and other toxic by-products out of the kidneys and prevent acute kidney injury (AKI). Intravenous fluids, typically isotonic saline, are administered to maintain high urine output (diuresis) of at least 200-300 mL/hour in adults.
Monitoring and Correction of Electrolyte Imbalances: Regular monitoring of electrolyte levels (such as potassium, calcium, phosphate) is essential. Electrolyte abnormalities, especially hyperkalemia (elevated potassium), should be promptly corrected to prevent cardiac arrhythmias and other complications.
Alkalization of Urine: Alkalinizing the urine with medications such as sodium bicarbonate can help prevent myoglobin from precipitating in the renal tubules, reducing the risk of kidney damage. This is particularly useful in cases of severe rhabdomyolysis or when myoglobinuria is present.
Treatment of Underlying Conditions: Addressing the underlying cause of muscle injury is crucial. This may involve discontinuing medications that contribute to rhabdomyolysis, treating infections, managing metabolic disorders, or addressing other contributing factors.
Diuretics: In some cases, loop diuretics (such as furosemide) may be used cautiously to enhance urine output and facilitate clearance of myoglobin from the kidneys. However, their use should be carefully monitored to prevent further electrolyte disturbances.
Monitoring Kidney Function: Continuous monitoring of kidney function through blood tests (creatinine, blood urea nitrogen) and urine output is essential. In severe cases of AKI, renal replacement therapy (such as hemodialysis or continuous veno-venous hemofiltration) may be necessary to support kidney function temporarily.
Supportive Care: Providing supportive care to manage symptoms, such as pain relief for muscle pain and discomfort, and ensuring adequate nutrition and rest for overall recovery.
Prevention of Complications: Close monitoring for potential complications, such as compartment syndrome (elevated pressure within muscle compartments), disseminated intravascular coagulation (DIC), and systemic inflammatory response syndrome (SIRS), and prompt intervention as needed.
Causes
Trauma: Traumatic injuries such as crush injuries, severe burns, car accidents, falls, or physical assault can directly damage muscle tissue, leading to rhabdomyolysis.
Extreme Physical Exertion: Intense or prolonged exercise, particularly in untrained individuals or under extreme conditions (e.g., marathon running, military training), can cause muscle breakdown and rhabdomyolysis. This is sometimes referred to as exertional rhabdomyolysis.
Ischemia: Reduced blood flow to muscles, which can occur in conditions like compartment syndrome (increased pressure within muscle compartments), vascular diseases, or prolonged immobilization (e.g., prolonged limb compression).
Medications and Toxins: Certain medications and toxins can induce rhabdomyolysis. Examples include statin medications (used to lower cholesterol), which rarely cause muscle injury, as well as drugs like cocaine, amphetamines, and heroin. Some toxins from snake or insect bites can also trigger rhabdomyolysis.
Infections: Viral infections, such as influenza, Epstein-Barr virus (EBV), and HIV, as well as bacterial infections like Group A streptococcus (causing necrotizing fasciitis), can lead to muscle inflammation and rhabdomyolysis.
Electrolyte Imbalances: Severe electrolyte abnormalities, such as hypokalemia (low potassium levels) or hypernatremia (high sodium levels), can disrupt muscle function and contribute to muscle breakdown.
Metabolic Disorders: Inherited metabolic disorders, such as McArdle disease (glycogen storage disease type V) or carnitine palmitoyltransferase deficiency, can impair energy metabolism in muscle cells, leading to rhabdomyolysis during periods of stress or exertion.
Heat Stroke: Severe overheating, such as in heat stroke or exertional heat illness, can cause muscle breakdown and rhabdomyolysis due to extreme body temperature elevation.
Other Causes: Other less common causes include autoimmune myopathies, muscle ischemia related to surgery or anesthesia, and severe hypothyroidism (myxedema coma).
Treatment
The treatment of acid-base disorders associated with diarrhea focuses on correcting fluid and electrolyte imbalances, managing acidosis, and addressing the underlying cause of diarrhea. Here’s how it is typically approached:
Fluid and Electrolyte Replacement:
- Oral Rehydration Therapy (ORT): Mild to moderate cases of dehydration can often be managed with oral rehydration solutions (ORS), which contain a balanced amount of electrolytes (sodium, potassium, chloride) and glucose to facilitate absorption.
- Commercial ORS packets are widely available and should be mixed with clean water according to instructions.
- Encourage frequent small sips rather than large amounts at once, especially in children.
- Intravenous Fluids: For severe dehydration or when oral intake is inadequate or contraindicated (e.g., altered mental status, persistent vomiting), intravenous (IV) fluids may be necessary.
- IV fluids may contain balanced electrolyte solutions (e.g., normal saline, Ringer’s lactate) to replenish fluid and electrolyte losses.
- Oral Rehydration Therapy (ORT): Mild to moderate cases of dehydration can often be managed with oral rehydration solutions (ORS), which contain a balanced amount of electrolytes (sodium, potassium, chloride) and glucose to facilitate absorption.
Bicarbonate Therapy:
- In cases where diarrhea-induced acidosis (metabolic acidosis) is severe or prolonged, supplemental bicarbonate may be considered.
- Bicarbonate can be administered intravenously under close monitoring of blood pH and electrolytes to correct acidosis.
Treatment of Underlying Cause:
- Depending on the underlying etiology of diarrhea (e.g., infection, inflammatory bowel disease), specific treatments may be necessary.
- Antibiotics may be indicated for bacterial infections causing diarrhea.
- Anti-diarrheal medications may be used cautiously in certain cases to manage symptoms, but they are typically avoided in infectious diarrhea as they can prolong the infection.
Nutritional Support:
- Maintaining adequate nutrition is crucial during and after diarrhea episodes.
- Once oral intake resumes, gradually reintroduce a normal diet, starting with easily digestible foods and avoiding high-fat or spicy foods that may aggravate diarrhea.
Monitoring and Supportive Care:
- Monitor fluid intake and output, electrolyte levels, and acid-base balance closely.
- Provide supportive care as needed, including pain management for abdominal discomfort and addressing any complications that may arise from severe diarrhea or acidosis.
Prevention:
- Educate patients on hygiene practices to prevent diarrheal illnesses, especially in settings where infectious diarrhea is common.
- Vaccination against pathogens that cause diarrhea, where available and appropriate, can also help prevent episodes.