Hardly a day has gone by in the past year when we didn't hear about the potential forpandemic influenza. Within the popular media, talk of the deadly ˙bird fluÓ often mentions that health experts fear the H5N1 strain of influenza Type A virus might mutate to unleash a global killer flu pandemic among humans. Pandemic influenza is touted as a disaster of unlimited potential faced by communities with limited resources.
Why the hysteria? Because history has shown the flu virus to be devastating. In 1918, the Spanish Flu killed an estimated 675,000 Americans. Applying similar attack and mortality rates to modern-day America, the Centers for Disease Control and Prevention (CDC) predicted an outbreak of a novel strain of pathogenic, highly transmissible Type A influenza would result in as many as 734,000 hospitalizations and 207,000 deaths. Other estimates go even higher to suggest as many as 1.9 million Americans would perish from pandemic influenza.
Intuitively, EMS practitioners and other health-care professionals would be among the groups most at risk for exposure to influenza or any other potentially catastrophic disease during an outbreak. Recent scientific literature raises the question, ˙Why are we the least prepared for the worst possible disaster?Ó
What can we do to better prepare medical personnel for the biological challenge posed by these threats? To start, we can draw on the lessons learned from the severe acute respiratory syndrome (SARS) outbreak of 2003 to make observations about EMS practitioners and other health-care workers faced with highly transmissible, deadly pathogens. Further, we must refresh ourselves on standard precautions and use a simple acronym, DOCTOR, to remind ourselves of when to take precautionary measures.
SARS in the West
On Feb. 23, 2003, in Toronto, the first case of the largest outbreak of SARS outside of Asia was diagnosed. From this transmission of the SARS virus, 375 individuals were infected and 44 died (11.7% case fatality rate). SARS was diagnosed in 8,098 individuals throughout the world from November 2002 through July 2003, and since that time numerous cases have been diagnosed in isolated areas. Many of those who were infected with SARS were health-care workers or individuals involved in the direct care of the first patient diagnosed with SARS in the West. The high proportion of cases among health-care workers in Hong Kong (62%) and Toronto (51%) indicated the threat was real.
Consider some of the sobering facts about SARS in Toronto: Of the nearly 375 people who contracted SARS in Ontario, 72% were infected in a health-care setting; of those infected in a health-care setting, 45% were health-care workers, mostly nurses. Further, many health-care workers, infected but undiagnosed with SARS, brought the illnessƒand in some cases, deathƒto their families at home.
How It Spreads
The respiratory illness known as SARS is caused by thecoronavirus SARS-CoV. SARS is transmitted through close person-to-person contact and is most readily spread by respiratory droplets (droplet spread) produced when an infected person coughs or sneezes. When an infected person coughs or sneezes, the droplets are propelled a short distance (generally up to 3 feet) through the air and are deposited on the mucous membranes of the mouth, nose or eyes of anyone nearby.
Close person-to-person contact involves caring for or living with a person known to have SARS or having a high likelihood ofdirect-contact transmission due to contact with respiratory secretions and/or bodily fluids of a person known to have SARS. Direct contact actions include kissing or embracing, sharing utensils, talking closely (within 3 feet), conducting a physical examination and having any other direct physical contact between people. SARS can also be transmitted when a person touches a surface or object contaminated with infectious droplets and then touches their mouth, nose or eyes.
Numerous other diseases follow the same mode of transmission as SARS. These include measles, mumps, rubella (German measles), diphtheria, pertussis (whooping cough), Haemophilus influenza B (Hib), varicella (chicken pox), influenza (flu), meningococcal meningitis and tuberculosis (TB), as well as the pneumonic plague. Each of these diseases can be transmitted through close person-to-person contact, and each can be easily transmitted to individuals who have had a high likelihood of direct contact with respiratory secretions.
Many individuals infected with one of these droplet-spread diseases, especially SARS, require respiratory support at various levels, including the non-critical level of supplemental oxygen use to the most critical level with manual ventilation. The respiratory support needed by the infected individuals can generate aerosolized droplets that can expose EMS practitioners to respiratory pathogens or infectious agents. According to the head of the Department of Medicine at the University of Calgary (Alberta), the ˙SARS outbreaks helped us to recognize the enhanced transmissibility of respiratory pathogens during respiratory procedures that may generate aerosol particles.Ó
Different types of respiratory support procedures generate aerosolized droplets that can expose EMS practitioners to an infectious agent. Some of these ˙high-risk proceduresÓ include nebulized therapy, aerosol humidification, bag-valve-mask (BVM) ventilation, endotracheal intubation and airway suctioning. During these and other high-risk procedures, EMS providers must practice infection control measures (as discussed below) and promote respiratory hygiene and cough etiquette for all patients with symptoms of a respiratory infection.
EMS providers are highly susceptible to becoming contaminated and infected with SARS and other infectious agents because of the procedures performed, low frequency of air circulation in the back of an ambulance and the confined working space of the prehospital environment. Thus, specific safety precautions and procedures must be established and followed. Providers working in the field or in the patient compartment of a transport unit, must donpersonal protective equipment (PPE) during high-risk procedures and patient care of individuals suspected of a respiratory infection.
Because the transmission can occur via droplet spread or contaminated surfaces, the mucous membranes of the mouth, nose and eyes of the provider must be protected. The CDC notes the PPE must be compatible with the needs of the health-care worker's protection and compatible with delivering patient care. Thus, providers should wear PPE that includes a disposable isolation gown, a pair of disposable patient examination gloves, eye protection (i.e., goggles or face shield) and respiratory protection (i.e., N-95 or higher-level respirator).
According to the CDC, wearing PPE protects the respiratory tract from inhalation of droplets and also prevents the mucous membranes, skin and clothing from having contact with infectious, aerosolized respiratory secretions.
The disposable isolation gown should have fluid-resistant properties and the gown should cover the exposed parts of the arms and body. A full-body isolation suit and a surgical hood have been used in some instances; however, these may not be compatible with delivering prehospital care. The disposable exam gloves should cover the entire hand and extend over the cuff of the gown.
Appropriate eye protection guards against respiratory splash or spray. Goggles should be snug but comfortable. Some providers may decide to use a face shield, which can be worn over goggles to protect exposed areas of the face; however, a face shield should not be worn as a primary form of eye protection.
All individuals involved with patient care and transport should wear respiratory protection. The CDC recommends disposableparticulate respirators (e.g., N-95, N-99 or N-100), which are the minimum level of respiratory protection required for health-care workers performing aerosol-generating procedures. Because the effectiveness of respiratory protection depends on a good mask-to-face seal, OSHA requires disposable respirators to be thrown away after each use and other respirators to be undergo afit test annually to ensure the fit is acceptable.
One report on the SARS outbreak indicates that although EMS providers who were exposed to SARS were wearing appropriate PPE, they had not been fit-tested for the respirator issued. This fact underscores the importance of having providers fit-tested for the respirator model they'll be issued and also trained on how to don, doff and clean the respirator (if not disposable).
Care with Caution
During the Toronto outbreak, local law enforcement isolated patients in hospitals, served quarantine orders and conducted spot checks on people in home quarantine. Specially equipped EMS units were available to transport people who became symptomatic to designated hospitals.
If an individual is suspected of having been exposed to an infectious agent or is exhibiting signs and symptoms of having been exposed to an infectious agent and is in a stable condition, you should employ standard precautions and instruct the patient on respiratory hygiene and cough etiquette. This etiquette involves instructing individuals to cover their nose and mouth when coughing or sneezing, to use tissues to contain respiratory secretions and to dispose of the tissue in the nearest waste receptacle after use. Good respiratory hygiene also includes performing hand hygiene (e.g., hand washing with non-antimicrobial soap and water, alcohol-based hand rub or antiseptic hand wash) after contact with respiratory secretions and contaminated objects or materials. Also, you should provide the individual with the materials to complete these activities.
If a patient requires a high-risk procedure, you should have the area isolated from unprotected individuals. If the patient requires resuscitation and ventilations by a BVM, then it should have ahydrophobic submicron filter. This kind of filter traps bacteria and viral particles and provides a defense against the transmission of aerosolized droplets. Training should involve the proper application of a BVM for airway management and the integration of the hydrophobic submicron filter during BVM use.
Individuals responsible for equipment purchasing should determine if the equipment being purchased for use in a high-risk procedure has an integrated hydrophobic submicron filter or has the ability to add one inline. An effort should be made by the purchaser to provide respiratory filters to providers in order to prevent transmission of aerosolized droplets during high-risk procedures.
If the patient doesn't require manual ventilations by a BVM but does require supplemental high-flow oxygen, you should use an oxygen mask that doesn't have side vents. Using this kind of mask forces all exhaled gas to exit through a single 22-mm port in the attached manifold. By placing a respiratory filter on the exhalation port, the filter prevents droplets from leaving the mask (according to recent studies).
Other Practical Considerations
During training, EMS practitioners often comment on their reluctance to wear respiratory protective equipment when attending to patients. As experienced trainers, we find that providers are frequently well into patient assessment before they recognize the need to adopt appropriate respiratory and droplet protective equipment. At this point, they may be so focused on the patient and life-saving measures that they fail to adopt such equipment, putting themselves, co-workers and family members at unnecessary risk for disease transmission.
To help providers remember to consider precautions, we've formulated a simple acronym, DOCTOR, which stands for difficulty breathing, occupation, contact history, temperature, out of country and rash (seeTable 1, p. 52). Prehospital use of the acronym allows for early assessment of a situation, including a phone assessment, to determine the likelihood of needing to adopt an aggressive posture when it comes to respiratory and droplet protective equipment. Training on this acronym takes less than 30 minutes. Further, if a provider suspects an unusual or contagious disease, they could quickly notify personnel at the receiving medical treatment facility, contact their supervisor or infection control officer, and a public health office (depending on local protocol).
Assuming providers may not have time to apply the DOCTOR acronym, you can learn a lot by asking one straightforward question before you enter the residence of a patient with an unknown illness: ˙Is anyone else sick in the house?Ó As we all know, simple measures are the easiest to implement. Regardless of the level of expertise and degree of training, the safety of EMS providers is of paramount importance.Conclusion
To limit the exposure for EMS providers during the care and transport of patients with respiratory infections, appropriate PPE must be worn and hydrophobic submicron filters should be utilized. To limit contamination of objects, we must observe additional precautionary measures and follow post-incident decontamination procedures (which should be the same as the decon procedures generally used for infection control).
Because many individuals infected with SARS in Toronto were health-care workers, the implementation of prevention programs could avoid a similar incident in the future. With appropriate safety precautions and procedures established and employed, the transmission of infectious respiratory agents can be minimized to protect our patients, ourselves and our families from the dark biological threat that may be lurking in our future.
Walter Eric Meyer IV, MPA-EM, NREMT-P, is affiliated with the City of Mountain Brook (Ala.) Fire Department.
Shannon W. Stephens is affiliated with the Department of Emergency Medicine and the Center for Emerging Infections and Emergency Preparedness at the University of Alabama at Birmingham.
Susan C. Meyer, DSN, RN, is a contract researcher at Huntsville Hospital and Clearview Cancer Institute in Huntsville, Ala.
Jan G.Glarum, EMT-P, is a private consultant in Alcoa, Tenn.
Jeffrey R. Ryan, PhD, is an assistant professor with the Institute for Emergency Preparedness at Jacksonville (Ala.) State University. Contact him firstname.lastname@example.org.
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