Decontamination Principles: Prevention of Dermal, Ophthalmic, and Inhalational Absorption




INTRODUCTION



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Decontamination is a term that describes limiting or minimizing the exposure of a patient to a xenobiotic. This involves removal of a xenobiotic by physical means or by chemical neutralization before it can be systemically absorbed. Despite limited controlled studies assessing its efficacy, decontamination remains the mainstay of initial treatment for a patient exposed to a potentially harmful xenobiotic. Decontamination strategies in toxicology often refer to gastrointestinal (GI) techniques to minimize absorption or enhance elimination in orally poisoned patients (Chaps. 5 and 6). These same principles apply to other exposure routes where local or systemic absorption and toxicity occur, including dermal, ophthalmic, and pulmonary routes. An important point to note is that as opposed to GI decontamination, in which initial patient assessment and management always comes first, in the case of dermal and pulmonary contamination, in which there is risk for contamination and harm to health care personnel, the use of appropriate personal protective equipment (PPE) is paramount before initiation of patient decontamination. The benefits of decontamination to remove or neutralize a xenobiotic are severalfold and include (1) prevention of further absorption and toxicity in exposed patients, (2) prevention of secondary contamination of other staff or equipment, and (3) prevention of contamination of the health care facility and other patients.



An organized approach to decontamination is required following the release of hazardous materials. Unintentional release of hazardous materials occurs at industrial sites, chemical manufacturing plants, pipelines, and waste sites.25 Also, the threat of terrorist attack using hazardous materials mandates that the health care community be prepared to effectively manage these situations in a safe and efficient manner that optimally treats patients while at the same time maintains the safety of the health care providers.



This Special Consideration focuses on situations that require health care facility–based dermal, ophthalmic, and pulmonary decontamination. The approach to the decontamination process is discussed, but the acute medical management of specific local and systemic toxicities is covered in other chapters. Dealing with mass casualty events and the incident command system, as well as prehospital decontamination are covered in detail elsewhere (Chap. 132). In addition, approaches to patient triage, runoff control, and isolation requirements are not covered here.




HAZARDOUS MATERIALS



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Typically, decontamination efforts are initiated by first responders, including hazardous materials teams (HAZMAT), who respond to the site of initial xenobiotic release. However, in an instance when emergency medical services (EMS) is unable or uncertain how to decontaminate a patient or for patients who self-present to the hospital, it is prudent that health care providers are prepared to carry out effective decontamination. In fact, up to 80% of patients from a scene of xenobiotic release self-present to a hospital without undergoing any prior decontamination, mandating that hospital personnel have the appropriate knowledge and follow an organized approach to patient decontamination to ensure their personal safety and the safety of other health care providers and patients.5,39,40 Close cooperation between the emergency department (ED) and prehospital providers, including HAZMAT teams responding to the initial site of exposure, help to identify the xenobiotic involved and help to guide decontamination efforts. Appropriate communication with these teams before hospital arrival is paramount to ED preparations for a particular xenobiotic number of patients being brought by EMS, degree of prehospital decontamination, and associated injuries. Secondary contamination data from the Agency for Toxic Substances and Disease Registry (ATSDR) Hazardous Substances Emergency Events ­Surveillance system was studied. Between 1995 and 2001, six events involving 15 ED personnel, and from 2003 to 2006, 15 events involving at least 17 medical personnel were identified in which secondary contamination occurred.20,21 After the Tokyo sarin subway attacks in 1995, many patients presented directly to a hospital as their first site of health care contact. Hospital-based decontamination attempts were not universal, with a limited number of patients receiving a change of clothes or shower, which resulted in approximately 23% of staff experiencing secondary contamination.41



A vast number of xenobiotics are involved in patient exposures, either from their deliberate use or from unintentional exposure. Identification of specific substances and their properties is helpful to determine specific toxic properties and the likelihood of systemic absorption. However, on initial hospital presentation, the exact xenobiotic or xenobiotics are often unknown, mandating that general safety and decontamination measures are promptly initiated to provide maximal safety to health care providers, with subsequent adjustments made as more product information becomes available.



In addition to concerns for toxicity related to hazardous materials, many of these exposures have nontoxicologic medical concerns that must be addressed simultaneously. Patients from industrial incidents often present with traumatic injuries or multiorgan dysfunction that require appropriate basic and advanced life support measures are instituted. Evaluation and support of patient airway, breathing, and circulation should ideally be done concomitantly with decontamination efforts, as long as health care providers are protected using appropriate PPE.




PERSONAL PROTECTIVE EQUIPMENT



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As noted earlier, the most important aspects of managing patients contaminated with hazardous materials are to protect health care providers and to prevent worsening the situation by creating additional exposed individuals. There are several levels of PPE, classified according to the Environmental Protection Agency from level A to D, that provide varied levels of protection against exposure to gases, vapors, aerosols, liquids, and solids. The type of exposure dictates the level of PPE that is required for appropriate (Chap. 132).




DECONTAMINATION



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Dermal Exposures



The majority of decontamination for patients presenting after hazardous materials exposures will involve dermal decontamination. Patients exposed to liquids, aerosols, or solids require dermal decontamination. Patients who do not pose a risk of secondary contamination to health care workers include those who have undergone appropriate prehospital decontamination and those exposed only to vapors or gases with no signs of skin or eye irritation and who do not have gross deposition of the material on their clothing or skin. These patients should proceed directly to the treatment area without further ED dermal decontamination.4,16,22,24 However, gases or vapors condense on patient clothing, leading to secondary contamination from off-gassing if appropriate care is not taken in managing personal belongings (see later discussion). In addition, if a patient has ingested a chemical, vomitus poses a danger to health care providers through direct contact or off-gassing.4 If able, patients should assist in their own decontamination efforts.



Methods of dermal decontamination include physical removal (clothing removal, removal of visible solid particles), adsorption (Fuller earth, activated charcoal, flour), dilution (flushing), or acts to neutralize the xenobiotic.30



Physical Removal



Before initiation of dermal decontamination, the most important step is to remove contaminated clothing, which removes from 75% to 90% of the contaminants.13,22,26,39 Clothing should be cut off rather than pulled off because pulling off clothing will worsen contaminant exposure to the patient and health care staff.22,39 Clothing and personal belongings should be double bagged in sealed plastic bags with the patient’s information written on it.3 Appropriate sealing is required to prevent evaporation or aerosolization of the xenobiotic.4,30 Dermal decontamination also includes physical removal of the xenobiotic with forceps or gentle removal with brushing or use of a towel on the skin. Another method is to gently scrape the xenobiotic from the skin using a flat edge such as a tongue depressor.24 Care must be taken to gently remove xenobiotics, as abrasive cleansers increase systemic absorption. Flushing the skin with copious amounts of water is also effective at physically removing xenobiotics.



A method of dry decontamination using activated charcoal, flour, or Fuller Earth is suggested by some groups to adsorb certain nerve agents and sulfur mustard, after which the adsorbed compound is gently brushed or wiped off with a towel.22,24 The US military also uses a compound called M-291, a carbon-based adsorbent–polystyrene polymeric–ion exchange resin, for local, dermal decontamination.22,24 Although dry decontamination is effective for localized exposures, it is unlikely to be useful in the hospital setting and therefore is not recommended because a lack of familiarity will lead to delays in initiating more effective decontamination strategies.



Dilution and Neutralization



Water only, soap and water, and 0.5% hypochlorite solutions are used to decontaminate skin after hazardous material exposures. The main factors determining usefulness of a hospital-based decontamination solution include safety (nontoxic and noncorrosive), availability, ease of use, affordability, and ease of disposal. The solution must also be nonirritating, rapid acting, and not produce toxic endproducts or enhance percutaneous absorption.11,24 Regardless of the solution used to flush contaminated skin, the most important factor is that it must be done as soon as possible to minimize the inflammatory response and potential for local and systemic toxicity; after a xenobiotic is absorbed, topical decontamination is of limited utility.



Flushing contaminated skin with high volumes of low-pressure water will aid in physical removal and significant dilution of the xenobiotic. A military study showed that an oil-based xenobiotic was removed from 90% of subjects within 30 seconds and 100% of subjects at 90 seconds using a water only decontamination method.36 Overall, showering with tepid water and liquid soap (mild, nonabrasive soap such as hand dishwashing soap) is the most effective, easiest, and most readily available method for removing hazardous materials from patients’ hair and skin.6,39 Use of alkaline soaps produces hydrolysis and neutralization of some xenobiotics; however, this contributes far less than the benefits of physical removal and dilution.24 In addition, for patients exposed to non–water-soluble, oily, or adherent xenobiotics such as mustard or blister agents, addition of mild liquid soap and gentle scrubbing with a sponge or cloth helps to aid removal. Skin damage should be avoided to prevent further absorption of the xenobiotic. Patients should be scrubbed downward from head to toe with care taken to avoid contaminating unexposed areas.



Chemical alteration and deactivation, including hydrolysis and oxidative chlorination, were studied by the military in response to chemical weapons and suggest some benefit. However, these approaches do not have any significant role in the hospital setting because they require prolonged contact time to be effective.22,32 Hydrolysis through the addition of acidic solutions is prohibitively slow, and alkaline solutions require a pH that would damage skin or mucosa (ie, pH 10–11).24 Oxidative chlorination with the addition of dilute (0.5%) hypochlorite solution, although still recommended by the military and effective for decontaminating oxidizing mustard agents and some organic phosphorus compounds, is not acceptable for use on ophthalmic or mucosal surfaces, in open wounds, or exposed nerve tissue.22,24 Both the difficulty in obtaining 0.5% hypochlorite solution and its propensity to worsen certain tissue injuries make its use impractical in the hospital setting.



There are no controlled studies to assess the optimal duration of showering or skin rinsing and no current consensus exists. Recommendations for duration of water-based decontamination range from 3 to 30 minutes.4,7,12,39,48 It is reasonable to wash exposed areas with tepid water and liquid soap for 5 to 15 minutes, with an additional 10 to 15 minutes for contaminated open wounds.7 The US military has several processes to assess efficacy of decontamination (eg, M8 paper, M9 tape, chemical agent monitor); however, these are not readily available or realistic for use in the hospital setting.24

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Nov 19, 2019 | Posted by in ANESTHESIA | Comments Off on Decontamination Principles: Prevention of Dermal, Ophthalmic, and Inhalational Absorption
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