Suppose you float to the oncology unit of your medical center and are assigned to a patient who has a sign on her door saying, “Neutropenic precautions.” Would you know how to provide safe care? If you’re not certain you’re up to date, read on.
With neutropenia, a patient’s circulating blood contains an abnormally low number of neutrophils—the mature white blood cells (WBCs) that attack and destroy invading bacteria, viruses, and fungi. That’s why neutropenic patients are highly susceptible to infections from other people and from their own endogenous bacteria. (See Fast facts on neutropenia in pdf format by clicking on the download now button.)
The most common cause of neutropenia is cancer treatment, particularly chemotherapeutic drugs. The incidence of neutropenia varies, depending on the specific drugs, the dose intensity, the number of myelosuppressive drugs, and the administration schedule. The higher the dose of myelosuppressive drugs, the higher the risk of neutropenia. Patients preparing for bone marrow or stem-cell transplantation have a particularly high risk because of the high doses needed. Anthracyclines such as doxorubicin are known for myelosuppressive toxicity.
Patients receiving external beam radiation therapy on large areas of bone marrow, such as the sternum, pelvis, and long bones, have a high risk of neutropenia, as do patients receiving both chemotherapy and radiation therapy. Other risk factors include diabetes, recent surgery, open wounds, infection, malnourishment during cancer treatment, and a history of neutropenia, chemotherapy, or radiation therapy. Patients with hepatic dysfunction demonstrated by an elevated bilirubin or alkaline phosphatase level and patients with renal dysfunction demonstrated by an elevated creatinine level are also at increased risk because of decreased metabolism and delayed elimination.
Patients with a tumor affecting the bone marrow usually have myelosuppression and neutropenia. So do patients with small-cell lung cancer, lymphoma, and breast cancer. Cancer patients older than age 70 who receive myelosuppressive chemotherapy are at increased risk for neutropenia and fatal infection, likely because of a decline in bone marrow reserves.
Calculating the absolute neutrophil count
The absolute neutrophil count (ANC) measures immune function more accurately than the total WBC count or the neutrophil count alone. The ANC considers both the circulating mature neutrophils and the immature WBCs, called the bands. You can cal-culate the ANC by using this formula.
ANC = ((% neutrophils+% bands)/100) x 3 WBC count
This example shows how to calculate the ANC of a patient with 50% neutrophils, 8% bands, and a WBC count of 4,000.
ANC = ((50% + 8%)/100) x 4,000
ANC = (0.50 + 0.08) x 4,000
ANC = 2,320
Infection risks and prevention
Neutropenia can lead to life-threatening infections. Generally, the longer the neutropenia lasts and the more severe it is, the more likely the patient will develop an infection. The National Cancer Institute has a grading scale correlating a patient’s ANC and the risk of infection. (See Determining the risk of infection in pdf format by clicking the download now button.)
The single most important preventive measure is hand washing. Before any contact with a neutropenic patient, caregivers and others should wash their hands. Other preventive measures have been tried, but there’s little evidence to support their use. However, many of these practices remain in place, so follow your institution’s guidelines.
Infections often develop from endogenous bacteria, so patients should maintain good personal hygiene, including hand washing and oral care. Patients should avoid crowds and others who are ill. Avoiding uncooked meats, seafood, eggs, and unwashed fruits and vegetables may be prudent, though the effectiveness hasn’t been established.
Procedures that break the skin, such as venipunctures, biopsies, and I.V. therapy, may also introduce infection. Because trauma to the mucous membranes increases the risk of infection, you shouldn’t use catheters, enemas, rectal suppositories, or rectal thermometers. Common infection sites include the mucosa of the GI, urinary, and respiratory tracts.
To prevent infection in patients at high risk for neutropenia, a physician may order a granulocyte-colony stimulating factor (G-CSF), such as filgrastim or pegfilgrastim. Current recommendations say these drugs should be given to patients whose risk for febrile neutropenia is 20% or higher.
The manufacturer recommends starting G-CSF therapy no earlier than 24 hours after chemotherapy to avoid stimulating cancer cells and exacerbating myelosuppression. These drugs accelerate neutrophil formation in the bone marrow, reducing the duration and severity of neutropenia. They don’t completely eliminate neutropenia or the risk of infection. Nor do they help treat patients who already have neutropenic fever.
Treating neutropenic fever
A neutropenic patient may not have the usual signs and symptoms of infection—redness, swelling, and pus formation—because he or she doesn’t have enough neutrophils to produce them. The most reliable, and often the only, sign is fever. Teach patients to monitor their temperature and seek medical attention immediately for temperatures of 100.4º F (38º C) or higher.
Neutropenic fever, usually defined as a single temperature greater than 100.4º F and an ANC of less than 500/mm3, is a medical emergency. If neutropenic fever isn’t managed quickly, life-threatening septic shock can develop. (See Responding to neutropenic fever in pdf format by clicking on the download now button.)
Patients with neutropenic fever are usually admitted to the hospital for cultures and broad-spectrum I.V. antibiotic therapy. Pathogens causing infections in cancer patients are usually endogenous flora colonizing the skin and the respiratory, genitourinary, and GI tracts. Between 85% and 90% of the pathogens are bacteria, and 60% to 70% are gram-positive. The most serious infections in oncology patients are from gram-negative organisms.
The recommended cultures include two sets of blood cultures and a urine culture. Depending on your institutional procedures, you may draw the blood using a peripheral site, a central venous access device, or a multilumen central catheter. Make sure you obtain 10 mL of blood per culture. Ideally, antibiotic therapy should start within 1 hour of detecting the fever.
Depending on the signs and symptoms, the patient may also need a culture of stool, skin, nares, or vascular access sites. A physician may also order a viral culture. Chest X-rays may be part of the workup, though findings are often absent in patients with a pulmonary infection.
Despite an episode of neutropenic fever, some low-risk patients can be treated as outpatients. These patients have no associated acute comorbid illness, a good performance status, no hepatic or renal insufficiency, and an anticipated neutropenia duration of less than 7 days. They may receive oral or I.V. antibiotic therapy in an ambulatory clinic or through a home health agency.
Teaching patients at risk
Teach cancer patients at risk for neutropenia to report any signs and symptoms of infection, particularly a fever with or without chills. Emphasize the urgency of seeking medical treatment regardless of the time of day. Explain that patients should contact their physicians immediately during office hours or go directly to the emergency department at other times. Be sure patients have an accurate thermometer and know how to use it.
During cancer therapy, reinforce the importance of basic hygiene. Patients and caregivers should wash their hands frequently, using soap and water or an alcohol-based hand sanitizer. Bathing daily, providing oral care three or four times a day, and thoroughly cleaning the perineal and rectal areas help minimize the risk of infection. Teach patients to avoid exposure to people who have colds or other contagious illnesses. Also explain that patients should avoid contact with animal urine and feces when cleaning birdcages and litter boxes. (See Finding reliable patient-teaching materials in pdf format by clicking on the download now button.)
Patients receiving chemotherapy face serious dangers. To help them avoid a life-threatening neutropenic infection, you need to provide safe, smart care and teach them safe self-care.
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Freifeld A, Segal B. Prevention and Treatment of Cancer-Related Infections. Fort Washington, PA: National Cancer Comprehensive Network; 2007. National Cancer Comprehensive Network. Practice Guidelines in Oncology; vol. 1.2007.
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journal for a complete list of selected references.
Nancy Thompson is an oncology clinical nurse specialist at the Swedish Cancer Institute in Seattle, Washington.