Decision Making in Emergency Critical Care
SECTION 15 - The ED-ICU Transfer of Care
Indications for Contact and Respiratory Isolation
Chanu Rhee and Michael Klompas
Emergency and intensive care department health care providers often encounter patients with suspected or confirmed infections due to transmissible organisms. Isolation of patients who are infected or colonized with selected high-risk organisms is a cost-effective means of reducing rates of nosocomial infection and is a core component of infection control programs.1,2 Isolation and precaution guidelines were first issued in 1970 by the Centers for Disease Control and were last updated in 2007.3 A basic understanding of infection control terminology and practice is an essential skill for the emergency physician caring for critically ill patients.
In addition to standard precautions, which are recommended in the care of all hospitalized patients, there are three isolation categories—contact, droplet, and airborne spread—that reflect the major modes of transmission of microorganisms in health care settings. This chapter summarizes the key components and indications for each type of isolation precaution. We also include an overview of empiric isolation precautions for common clinical syndromes for use when the pathogen is unknown.
Standard precautions are recommended in the care of all hospitalized patients, in order to reduce the risk of transmission of infectious agents between patients and health care workers. Standard precautions include the following:
- Practice hand hygiene before and after every patient contact.
- Use gloves, gowns, and eye protection when exposure to body secretions or blood is likely.
- Safely dispose of sharp instruments and needles in puncture-resistant containers.
- Carefully handle soiled patient care materials and linens so as to avoid skin and mucous membrane exposures. Store soiled linens in impervious bags.
- Use safe injection practices.
- Practice respiratory hygiene and cough etiquette, which involves covering the nose and mouth when coughing, prompt disposal of tissues, and hand hygiene after contact with respiratory secretions. This also applies to all patients and accompanying family/friends with signs of respiratory illness (cough, congestion, rhinorrhea).
Hand hygiene is the single most important measure for reducing transmission of microorganisms.4 Hand cleansing with alcohol-containing disinfectants is more efficient than hand washing with soap and water. Note, however, that alcohol-based disinfectants are not effective against Clostridium difficile spores.5,6
Contact precautions prevent transmission of infectious agents, which may colonize patients' skin, wounds, and mucous membranes, as well as the inanimate environment. Contact precautions are applied to patients with multidrug-resistant bacteria (such as methicillin-resistant Staphylococcus aureus [MRSA], vancomycin-resistant Enterococcus [VRE], and some Gram negatives), diarrheal illnesses, draining wounds or abscesses, selected respiratory pathogens, and vesicular rashes (Table 63.1). Contact precautions are necessary every time a provider enters a patient room, regardless of whether or not he or she plans to touch the patient, since inanimate objects in the patient's environment are as likely to harbor pathogens as the patient himself.
TABLE 63.1 Indications for Contact Precautions
Contact precautions include the following steps:
- Use gloves and gowns for all contact with patients and their environment. Remove both gloves and gowns prior to leaving the patient's room.
- Wash hands before entering and after leaving patient rooms. Hands must still be washed before and after donning or removing gloves.
- Place patients in a private room whenever possible. If this is not possible, cohort infected patients with other patients on contact precautions for the same organism.
- Dedicate inexpensive items, such as stethoscopes, to a single patient.
There is some controversy regarding the use of contact precautions for drug-resistant pathogens like MRSA and VRE. Health care workers spend less time in the rooms of patients on contact precautions, compared to those on standard precautions, and this may impair the quality of care.7 In addition, a recent cluster-randomized trial involving multiple ICUs compared an intervention of enhanced surveillance for MRSA and VRE (through serial nasal and stool/perianal cultures) to standard care.8 Despite increased use of contact precautions in the intervention group (due to more patients being identified as being colonized with MRSA or VRE), there was no significant change in incidence rates of ICU infection or colonization with those pathogens. The study, however, was confounded by long turnaround times for screening results and suboptimal compliance with hand hygiene and contact precautions. On the other hand, implementation of a multifaceted MRSA “prevention bundle” that included contact precautions as well as universal surveillance, culture change, and emphasis on hand hygiene was associated with a significant decline in healthcare-associated MRSA infections at Veterans Affairs hospitals across the country.9
Emerging data suggest that an alternate strategy involving universal decolonization of all critically ill patients with nasal mupirocin and chlorhexidine baths is superior to screening and isolation or targeted decolonization (i.e., screening, isolation, and decolonization of MRSA carriers) in reducing the presence of MRSA and rates of all bloodstream infections.10 For now, however, practitioners are advised to refer to their local institution's policies.
Droplet precautions prevent transmission of pathogens spread through respiratory secretions. These pathogens are predominantly viral, but include notable bacterial pathogens such as Neisseria meningitidis, Haemophilus influenzae type B, invasive group A streptococcal infections, and diphtheria (Table 63.2). Droplets are particles of respiratory secretions with mean diameter of larger than 5 μm. They remain suspended in the air only for limited periods and so are generally infectious over short distances (typically less than 3 feet). Unlike airborne pathogens, droplets do not require special air handling and ventilation to prevent transmission. Note that some organisms, such as respiratory viruses, can be transmitted by both droplets and direct patient contact; these require both droplet and contact precautions. Droplet precautions entail the following:
TABLE 63.2 Indications for Droplet Precautions
- Wear a mask for close contact with patients (within 3 feet). A respirator (such as an N95 mask) is not necessary.
- Place the patient in a private room if possible. If cohorting of patients possessing the same pathogens is necessary, place patient beds at least 3 feet apart and draw the curtains between beds.
- Place a mask on the patient during transport.
For influenza, studies have specifically compared the use of N95 respirators to standard masks and have found no difference in rates of transmission.11,12
Airborne precautions prevent transmission of pathogen-laden droplets that can remain suspended in the air for prolonged periods. Airborne droplet nuclei are particles of respiratory secretions with mean diameter of 1 to 5 μm. In contrast to contact and droplet precautions, the list of pathogens that require airborne precautions is short: suspected or confirmed tuberculosis, measles, varicella–zoster, smallpox, and severe acute respiratory syndrome (SARS). In addition, a novel coronavirus (now designated as the Middle East respiratory syndrome coronavirus, or MERS-CoV) has recently emerged that, similar to SARS, can cause severe lower respiratory tract infection. While the exact nature of exposure causing infection in the MERS-CoV is not known at this time, human-to-human transmission has been observed, including health care–associated clusters of infection. Clinicians should suspect MERS-CoV in patients (or their close contacts) who developed fever and an acute lower respiratory illness within 14 days after traveling from countries in areas involved in the outbreak (which currently includes countries in the Arabian Peninsula). Currently, the recommended infection control policy is the same as that for SARS and includes both airborne and standard precautions.13 Airborne precautions entail the following:
- Place the patient into an airborne infection isolation room. This means a single-patient, negative pressure room with at least 6 to 12 air exchanges per hour. The air should be exhausted directly to the outside or recirculated through HEPA filters before return.
- Wear a certified respirator (e.g., N95 mask or powered air-purifying respirator) when entering the room. Health care providers need to be fit tested for N95 masks annually. Providers unable to establish an adequate fit with an N95 mask must wear a powered air-purifying respiratory mask instead.
- When possible, assign immune health care workers to care for patients with vaccine-preventable airborne diseases: measles, varicella, and smallpox.
- Minimize patient transport; if this is unavoidable, place a mask on the patient (a regular surgical mask is adequate).
Tuberculosis is the most important pathogen requiring airborne precautions, and it should be suspected in any patient with fever, cough, and upper lobe infiltrate. The threshold for airborne isolation should be very low in patients with HIV/AIDS presenting with fever and a pulmonary infiltrate, especially as they are much more likely to have an atypical appearance on chest radiography. Note that although guidelines recommend discontinuation of airborne precautions once patients are smear negative on three consecutive samples, transmission can still occur in these situations (although at a much lower rate) (Tables 63.3 and 63.4).14
TABLE 63.3 Indications for Airborne Precautions
TABLE 63.4 Common Clinical Syndromes That Warrant Empiric Precautions
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