Читать книгу Emergency Medical Services - Группа авторов - Страница 504

Influenza classically presents with the abrupt onset of fever, usually 38‐40 degrees C, sore throat, nonproductive cough, myalgias, headache, and chills. Influenza is caused by a virus with three subtypes in humans: A, B, and C. Influenza A causes more severe disease and is mainly responsible for pandemics. It has different subtypes determined by surface antigens H (hemagglutinin) and N (neuraminidase). Influenza B causes more mild disease and mainly affects children. Influenza C rarely causes human illness and is not associated with epidemics [3].

Influenza transmission occurs primarily through droplets when a person coughs or sneezes but may also occur indirectly by contact with surfaces contaminated by respiratory secretions. Handwashing and shielding coughs and sneezes help to prevent spread. Influenza is transmissible from 1 day before symptom onset to approximately 5 days after symptoms begin and may last up to 10 days in children. Time from infection to development of symptoms is 1‐4 days [4].

Influenza has been responsible for at least 31 pandemics in history. The most lethal “Spanish flu” pandemic of 1918‐1919 is estimated to have caused 50 million deaths globally with 700,000 of those deaths occurring in the United States in a single year. In this pandemic, deaths occurred mainly in healthy 20‐ 40‐year‐olds, which differs from the usual pattern of mortality and morbidity in young children and the elderly during seasonal outbreaks of influenza.

Table 23.1 Suggested Personal Protective Equipment Based on Procedure or Intervention

Intervention	Gloves	Facial and Eye Protectiona	Gowns
Drawing blood or starting an IV/IO line	Yes	No	No
Controlling minor bleeding with pressure or dressing minor skin wound	Yes	No	No
Contact with patient with cough or vomiting	Yes	Yes	Yes (if febrile respiratory illness or vomiting)
Needle thoracostomy	Yes	Yes	Yes (if febrile respiratory illness present)
Tracheal intubation	Yes	Yes	Yes (if febrile respiratory illness present)
Oral or nasal suctioning	Yes	Yes	Yes (if febrile respiratory illness or vomiting present)
Controlling arterial or heavy venous hemorrhage	Yes	Yes	Yes
Emergency childbirth	Yes	Yes	Yes
Known infection or colonization with antibiotic‐resistant organism (VRE, MRSA, etc.)	Yes	No (unless cough present)	Yes
Disinfecting or cleaning contaminated equipment or transport vehicle	Yes	Yes	Yes
When in doubt: always use the maximum, not the minimum, PPE

^a If an aerosol‐generating medical procedure is anticipated or the patient is known to have a communicable disease that is known to be spread by the airborne route, an N95 respirator is the preferred mask to be worn by personnel treating or in close proximity to the patient.

Table 23.2 Suggested Precautions Based on Suspected Infection

Level 1a	Level 2b	Level 3c
Abscesses	Chicken pox	AIDSd
Diarrhea	Common cold	Clostridium difficile e
Hepatitis A	Croup	Hepatitis Bd
Hepatitis E	Diphtheria	Hepatitis Cd
Cytomegalovirus	Epiglotitis	Hepatitis Dd
Herpes simplex	German measles (rubella)	Coronavirusesf during known outbreaks or when virus known to be producing rapid person‐to‐person spread
Herpes zoster	Red measles	Influenza (if contact with respiratory secretions is likely)
Lice	Herpes zoster	Viral hemorrhagic feversg (Ebola, Marburg, Crimean‐Congo, Lassa)
Viral meningitis	Infectious mononucleosis
Scabies	Meningitis, meningococcal
Syphilis	Meningitis, Haemophilus influenza
	Mumps
	Pharyngitis
	Pneumonia
	Streptococcus
	Tuberculosis
	Whooping cough

^a Gloves and handwashing.

^b Level 1 plus mask (N95 if airborne or high‐risk pathogen) and full face shield.

^c Level 2 plus disposable impermeable gown.

^d Level 3 if exposure to blood or body fluid is anticipated; otherwise, Level 1 precautions are appropriate.

^e Level 2 is adequate is there is no risk of soiling clothes or uniform. However, if the patient has any risk of soiling, Level 3 precautions are necessary.

^f Although transmission of coronaviruses (SARS, MERS, COVID‐19) may be considered to be similar to other highly contagious viral agents listed requiring Level 2 precautions, these viruses require Level 3 precautions, particularly in outbreak situations. In addition, special precautions may be required when transporting patients with coronaviruses.

^g Special precautions are required when transporting patients who are symptomatic with known of suspected viral hemorrhagic fevers.

Annual vaccination is the best way to prevent influenza, because vaccination can be given well before influenza virus exposures occur and can provide safe and effective immunity throughout the influenza season. Influenza vaccine is the principal means of preventing morbidity and mortality. The vaccine changes yearly based on the antigenic and genetic composition of circulating strains of influenza A and B found in January to March, when influenza reaches its peak activity. When the vaccine strain is similar to the circulating strain, influenza vaccine is effective in preventing illness among 70‐90% of those younger than 65 years who are vaccinated. Among those aged 65 years and older, the vaccine is 30‐40% effective in preventing illness, 50‐60% effective in preventing hospitalization, and up to 80% effective in preventing death. EMS personnel should be immunized annually, ideally as soon as the vaccine is available locally.

Six licensed prescription influenza antiviral drugs are approved by the U.S. Food and Drug Administration (FDA), four of which (oseltamivir, zanamivir, peramivir, and baloxavir marboxil) were recommended for the 2019‐2020 influenza season. When used for prevention of influenza, they can be 70‐90% effective. However, antiviral agents should be used as an adjunct to vaccination, and not replace it.

The Centers for Disease Control and Prevention (CDC) does not recommend widespread, routine, or pre‐exposure use of antiviral medications for chemoprophylaxis except under specific circumstances [3]. These include short‐term pre‐exposure chemoprophylaxis for unvaccinated health care personnel who are in close contact with persons at high risk of developing influenza complications during periods of influenza activity, when influenza vaccination is contraindicated or unavailable and these high‐risk persons are unable to take antiviral chemoprophylaxis. In addition, there is some weak evidence to suggest that antiviral post‐exposure chemoprophylaxis for unvaccinated EMS personnel can be used during periods of influenza activity when influenza vaccination is contraindicated or unavailable [5, 6]. If post‐exposure chemoprophylaxis is given, it should be administered as soon as possible after exposure, ideally no later than 48 hours. In the setting of an influenza outbreak, EMS systems may opt to restrict duties for EMS clinicians who are not immunized or who have not yet received prophylactic antiviral therapy, in attempts to prevent spread of influenza.