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Narcolepsy
Description
Narcolepsy is a chronic neurologic disorder caused by the brain’s inability to regulate sleep-wake cycles normally. During the day, people with narcolepsy experience uncontrollable urges to sleep. As the urge to sleep becomes overwhelming, individuals fall asleep for a few seconds to several minutes.
■ Narcolepsy typically occurs in adolescence or early in the third decade.
■ Head trauma, sudden change in sleep-wake habits, and infection may trigger symptom onset.
Narcolepsy can occur with cataplexy, which is a brief and sudden loss of skeletal muscle tone or muscle weakness.
Pathophysiology
The cause of narcolepsy remains unknown. It is associated with a deficiency of orexin (hypocretin), a neuropeptide linked to waking, from the destruction of orexin neurons. An autoimmune process is suspected for the neuron loss.
Clinical manifestations
Manifestations in some patients include brief episodes of sleep paralysis, hallucinations, cataplexy, and fragmented nighttime sleep.
Diagnostic studies
Diagnosis is based on a history of sleepiness, polysomnography (PSG), and daytime multiple sleep latency tests (MSLTs). For MSLT, patients undergo an overnight PSG evaluation followed by four or five naps scheduled every 2 hours during the next day. Short sleep latencies and onset of REM sleep in more than two MSLTs are diagnostic signs of narcolepsy.
Nursing and collaborative management
Management of narcolepsy is focused on symptom management. Narcolepsy cannot be cured.
Excessive daytime sleepiness and cataplexy can be controlled with drug treatment (see Table 8-8, Lewis et al.: Medical-Surgical Nursing, ed. 9, p. 107).
Nausea and vomiting
Description
Nausea and vomiting are the most common manifestations of GI diseases. Although each symptom can occur independently, they are closely related and usually treated as one problem. They occur in a wide variety of GI disorders and in conditions unrelated to GI disease, including pregnancy, infection, central nervous system (CNS) disorders (e.g., meningitis), cardiovascular problems (e.g., myocardial infarction [MI], heart failure [HF]), metabolic disorders (e.g., diabetes mellitus), side effects of drugs (e.g., chemotherapy, digitalis), and psychologic factors (e.g., stress, fear).
Nausea is a feeling of discomfort in the epigastrium with a conscious desire to vomit. Anorexia usually accompanies nausea.
Vomiting is a complex act that results in the forceful ejection of partially digested food and secretions (emesis) from the upper GI tract.
Pathophysiology
A vomiting center in the brainstem coordinates the multiple components involved in vomiting. Neural impulses reach the vomiting center by way of afferent pathways through branches of the autonomic nervous system. Receptors for these afferent fibers are located in the GI tract, kidneys, heart, and uterus. When stimulated, these receptors relay information to the vomiting center, which initiates the vomiting reflex. The simultaneous closure of the glottis, deep inspiration with contraction of the diaphragm in the inspiratory position, closure of the pylorus, relaxation of the stomach and lower esophageal sphincter, and contraction of the abdominal muscles with increasing intraabdominal pressure force stomach contents up and out of the mouth.
In addition, the chemoreceptor trigger zone (CTZ) located in the brain responds to chemical stimuli of drugs and toxins. Once stimulated (e.g., motion sickness), the CTZ transmits impulses directly to the vomiting center.
Clinical manifestations
When nausea and vomiting occur over a long period, dehydration can develop rapidly. Water and essential electrolytes (e.g., potassium, sodium, chloride, hydrogen) are lost. As vomiting persists, the patient may have severe electrolyte imbalances, loss of extracellular fluid volume, decreased plasma volume, and eventually circulatory failure.
The threat of pulmonary aspiration is a concern when vomiting occurs in older or unconscious patients or those with other conditions that impair the gag reflex. To prevent aspiration, put the patient who cannot adequately manage self-care in a semi-Fowler’s or side-lying position.
Collaborative care
The goals of management are to determine and treat the underlying cause of nausea and vomiting and provide symptomatic relief. Assess the patient for precipitating factors, and describe the contents of the emesis.
It is important to differentiate among vomiting, regurgitation, and projectile vomiting. Regurgitation is an effortless process in which partially digested food slowly comes up from the stomach. Retching or vomiting rarely occurs before it. Projectile vomiting is a forceful expulsion of stomach contents without nausea and is characteristic of CNS (brain and spinal cord) tumors.
The use of drugs in the treatment of nausea and vomiting depends on the cause of the problem. Because the cause cannot always be readily determined, use drugs with caution. Using antiemetics before determining the cause can mask the underlying disease process and delay diagnosis and treatment. Many antiemetic drugs act in the CNS via the CTZ to block the neurochemicals that trigger nausea and vomiting.
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