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Diagnosis
The differential diagnosis of fever is complicated by the variety of possible causes. In most cases, the patient's history—including a medication history and history of exposure to infectious diseases—vital signs, a complete blood count, and blood cultures will help to narrow the number of possible causes. In fevers of unknown origin (FUOs), however, the physician may need to schedule a chest x-ray or ultrasound and CT imaging.
Fevers of unknown origin (FUOs)
The origin of some fevers is difficult to determine. The term "fever of unknown origin" (FUO) has been applied to cases of fever in which the patient's temperature remains over 101°F (38.3°C) for three weeks and in which the diagnosis is not apparent after seven or more days of studies. The most common cause of FUOs is an infectious disease of some kind, although many cancers present initially as FUOs. About 15% of FUOs never receive a definite diagnosis.
Temperature measurement
A variety of different devices are available to register body temperature, including the traditional glass thermometers used for oral or rectal temperature readings. More recently, sophisticated electronic devices have been introduced that register body temperature as a digital readout. For younger children and infants, there are fore-head meter strips and pacifiers with temperature-sensitive readouts.
Routine measures
Most fevers are caused by common infections, are short-lived, and do not require symptomatic treatment. The patient's comfort, however, may be improved by measures to remove body heat, antipyretic medications, and fluid replacement. Measures to remove body heat include alcohol or cold sponges; ice bags; and ice baths. The most common antipyretic medications are aspirin or acetaminophen, 350–650 mg every four hours. Children or adolescents with influenza-like symptoms should not be given aspirin without consulting a physician because of the possibility of developing Reye's syndrome, a rare disorder characterized by vomiting and liver dysfunction.
Fluid replacement is an important part of fever treatment. Extra fluid is required to prevent electrolyte imbalance as well as to replace fluid lost through perspiration.
Emergency treatment
Body temperature over 105.8°F (41°C) in an adult is a medical emergency and requires immediate treatment.
The following indications in specific patient groups may require emergency treatment:
- newborns (three months or younger) with fever of 100.5°F (38°C) or higher
- infants or children with fever of 103°F (39.4°C) or higher
- adults with fever of 101°F or higher lasting longer than three days; or a temperature of 100.5°F lasting longer than three weeks without other symptoms
A very high fever in a small child can trigger febrile seizures, and therefore requires immediate treatment. A fever accompanied by a stiff neck, severe headache, throat swelling, and changes in mental status may indicate the presence of meningitis or another serious infection, and should be brought to the immediate attention of a physician. High fever does not always produce sweating or diaphoretic symptoms, which indicates weakness in the body's defenses against severe disease.
Prognosis
Most fevers caused by infection end as soon as the immune system rids the body of the pathogen and do not produce any lasting effects. Exceptions include fevers associated with meningitis, typhoid, or scarlet fever. High fevers can produce major disturbances of the body's metabolism and alter the body's responses to medications. In addition, a high fever during the first trimester of pregnancy increases the risk of such birth defects as anencephaly (absence of a portion of the skull and brain).
The prognosis for fevers associated with such chronic conditions as autoimmune disorders depends on the stage of the disease and its management.
Health care team roles
Nurses assess and record the fever patient's signs and symptoms. Nurses as well as physicians can obtain relevant information from the patient's medical history. Home health care and visiting nurses may also help to educate patients about at-home treatment of fevers. In some cases, home care nurses may counsel patients and caregivers over the phone, advising when the condition warrants in-person medical attention.
Prevention
Since most fevers are caused by infectious agents, careful attention to proper methods of food handling, hand washing, and similar public health measures is an important form of prevention. Fevers related to medication reactions can sometimes be prevented by substitution of drugs that are less likely to produce such reactions. Fevers related to indwelling catheters and similar devices may be avoided by removing them as soon as they are no longer required.
Hyperthermia related to environmental conditions may be prevented by proper attention to climatic conditions, adequate fluid and electrolyte intake, and acclimatization to hot environments. Educating the public about the early signs of heat disorders is another important preventive measure.
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Author Info: Lisette Hilton, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Nursing and Allied Health, 2002 |
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