PANCE Blueprint Pulmonary (9%)

5 y/o with fever and emesis

Patient will present as → a  5-year-old with sudden onset of fever, chills, malaise, sore throat, headache, and coryza. The child is also complaining of myalgia, especially in her back and legs. On physical exam, the patient appears lethargic, has a temperature of 102.5 F, and palpable cervical lymph nodes. Breath sounds are distant with faint end-expiratory wheezes. CXR demonstrates bilateral diffuse infiltrates.

Influenza is a viral respiratory infection caused by orthomyxovirus, resulting in fever, coryza, cough, headache, and malaise - three strains exist: A, B, and C

• Patients will present with fever, headache, myalgia, and malaise
• Complications from influenza are most common in the very young, the very old, and those with preexisting comorbidities

Antivirals are most effective if administered within the first 48 hours and reduce the duration of illness by about one day

• Four antiviral medications approved by the U.S. FDA are recommended
  • Inhaled Zanamivir (Relenza), oral Oseltamivir (Tamiflu), and intravenous peramivir (Rapivab) are all neuraminidase inhibitors and treat influenza A and B
  • The fourth drug, which is oral baloxavir (Xofluza), is active against both influenza A and B viruses and is a cap-dependent endonuclease inhibitor that interferes with viral RNA transcription and blocks virus replication
• Amantadine and Rimantadine are in a class of medications known as adamantanes, which target the M2 ion channel protein of influenza A viruses

Diagnosis is based primarily on patient history. A rapid antigen test can be performed in the clinic - the virus can be isolated from the throat or nasal mucosa

• Rapid serology tests are often available and are most accurate during the first few days of illness
• Gold standard = RT-PCR or viral culture takes 3-7 days to return
• CXR in primary influenza pneumonia will show bilateral diffuse infiltrates

Chest radiograph from a patient with viral pneumonia showing widespread bilateral interstitial infiltrates

Who to treat: start an antiviral as soon as possible, without waiting for test results, in any patient who is hospitalized, has severe, complicated, or progressive illness, or is at higher risk for complications (age ≥ 65, children < 5 and especially < 2, pregnancy and up to 2 weeks postpartum, chronic lung/heart/kidney/liver/metabolic disease, immunosuppression, body mass index ≥ 40, long-term care residents). In these groups, treat even if symptoms have been present for more than 48 hours. For otherwise healthy outpatients, antivirals are optional and only help if started within the first 48 hours of symptom onset (they shorten illness by about one day).

Amantadine and rimantadine are adamantanes that block the M2 ion channel of influenza A only. They are no longer recommended for treatment or prophylaxis because circulating influenza A strains are almost universally resistant.

Supportive care is the mainstay for healthy outpatients: rest, fluids, and acetaminophen or ibuprofen for fever and myalgias. Salicylates should be avoided in anyone under 18 because of the association with Reye syndrome - remember that bismuth subsalicylate (Pepto-Bismol) contains salicylate too.

Responsible use of antivirals:

• Do not delay treatment while waiting for testing - a negative rapid antigen test does not rule out influenza in a hospitalized or high-risk patient
• Antivirals are recommended for every hospitalized patient and for every high-risk outpatient (e.g., diabetes, coronary heart disease, COPD, asthma, pregnancy, age ≥ 65), regardless of illness duration
• Antivirals may be offered to healthy, low-risk outpatients whose symptoms began within the past 48 hours and who wish to shorten their illness; otherwise symptomatic treatment alone is appropriate
• Post-exposure chemoprophylaxis (oseltamivir, zanamivir, or baloxavir) can be considered for high-risk close contacts when started within 48 hours of exposure - it is not a substitute for vaccination
• Antiviral resistance patterns can shift from season to season; check www.cdc.gov/flu or the local health department for current guidance

CDC guidelines for influenza outbreak management in long-term care facilities and post-acute care facilities

When at least 2 patients are ill within 72 hours of each other and at least one resident has laboratory-confirmed influenza, the facility should promptly initiate antiviral chemoprophylaxis with oral oseltamivir to all non-ill residents living on the same unit as the resident with laboratory-confirmed influenza (outbreak affected units), regardless of whether they received influenza vaccination during the current season.

• Consideration may be given for extending antiviral chemoprophylaxis to residents on other unaffected units or wards in the long-term care facility based upon other factors (e.g. unavoidable mixing of residents or staff from affected units and unaffected units).

Influenza Antiviral Medications at a Glance (per CDC) – all four cover influenza A and B

Adamantanes (amantadine, rimantadine) are not recommended – circulating influenza A viruses are resistant.