- A poorly understood illness characterized by pervasive, chronic, and incapacitating fatigue.

Causes and Incidence The etiology is unknown, although popular theories propose a viral link or an overactive immune system. Chronic fatigue syndrome is a relatively new phenomenon and is most often associated with professionals in their 20s and 30s. The syndrome is diagnosed in women twice as often as in men.

Disease Process Unknown.

Symptoms The primary symptom is persistent or relapsing debilitating fatigue that does not respond to bed rest and that reduces normal activity levels by 50% or more for 6 months or longer. Other signs and symptoms include low-grade fever; sore throat; pharyngitis; painful, palpable cervical or axillary lymph nodes; myalgia; arthralgia; sleep disturbances; depression; and inability to concentrate.

Potential Complications None known.

Diagnostic Tests No definitive test exists. A clinical evaluation that includes the primary symptom plus six to eight of the other signs and symptoms is the most reliable indicator. Tests to rule out other disorders (e.g., leukemia, lymphoma, underlying psychiatric disorders) are important.

Treatments

Surgery – None.

Drugs
Investigational antiviral drugs and immune modulators are under study in clinical trials.

General
Supportive measures; balanced regimen of exercise and rest cycles; counseling for depression; support groups for coping.

Disease Process The initial injury to the lung is poorly understood. It is hypothesized that activated WBCs and platelets accumulate in the capillaries, interstitium, and air spaces and release prostaglandins, oxygen radicals, proteolytic enzymes, and other products. These injure the cells, increase fibrosis, and reduce bronchomotor tone, leading to capillary leakage of blood and plasma into the interstitial and alveolar spaces. This results in alveolar flooding and reduced surfactant activity, producing atelectasis. Bronchial inflammation and proliferation of epithelial and interstitial cells follow. Collagen accumulates, resulting in severe interstitial fibrosis (stiff lung) with low lung compliance, reduced functional residual capacity (FRC), pulmonary hypertension, perfusion maldistribution, and hypoxemia.

Symptoms

Early
Dyspnea, particularly on exertion, followed by rapid, shallow respirations, inspirational chest retractions, and wheezing

Late
Bloody, sticky sputum; racing heart rate; clammy, mottled, cyanotic skin; severe difficulty breathing; confusion; coma

Potential Complications Complications include secondary bacterial superinfections, tension pneumothorax, multiple-system organ failure, metabolic and respiratory acidosis, and cardiac arrest.

Diagnostic Tests

Pulmonary function
Decreased FRC and compliance; low/normal pulmonary capillary web pressure; increased shunt fraction

Arterial blood gases
Decreased PaO2; low/normal PaCO2; elevated pH

Lactic acid
Elevated

Radiology
Blurred margins and alveolar infiltrates on early chest x-rays; normal cardiac silhouette

Treatments Mechanical ventilation with positive end-expiratory pressure and continuous positive airway pressure is generally required until the underlying problem has been identified and treated.

Surgery – None.

Drugs
No specific drugs; morphine and pancuronium bromide (Pavulon) are used in the management of mechanical ventilation; antiinfective drugs may be used for underlying infections.

General
Correction of underlying cause of injury; hyperalimentation to prevent nutritional depletion; blood gas monitoring to prevent oxygen toxicity; careful aseptic technique and monitoring of secretions to prevent superinfection; intubation and ventilation; tracheobronchial suctioning to clear secretions; cardiac monitoring; bed rest; fluid volume replacement; regulation of activity to reduce hypoxia; instruction in communicating with intubated patient; communication tools (e.g., alphabet or picture boards, response switches).