Correspondance

supplied to the registry. Registries protection would be an N100 Compassionate care should use appropriate methods for as- with an ultra-low penetrating air filter sessing these criteria. (ULPA), which would cost only slightly s one of the physicians consulted more than an N95 respirator. N100 Aon Human Resources Develop- Warren T. Blume have an efficiency of ment ’s new compassionate Department of Clinical Neurological 99.977%,8 and ULPA filters are leave program for people caring for Sciences, Epilepsy and Clinical 99.999% efficient for monodispersed gravely ill or dying children, parents or Neurophysiology particles 0.12 µm in diameter or larger.9 spouses, I was disappointed by the title, London Health Sciences Centre — HEPA (high-efficiency particulate air) tone and emphasis of the CMAJ news University Campus filters would not be the best selection item on this topic.1 This is just the type London, Ont. for use with a respirator because their of program that Canadian physicians efficiency is 99.97% for monodispersed should support and take pride in. Em- Reference 1. Blume WT. Diagnosis and management of particles 0.3 µm in diameter or larger, phasizing that this benefit entails “more epilepsy. CMAJ 2003;168(4):441-8. and coronaviruses are smaller than this paperwork for physicians” is misguided (at about 60 to 200 nm). For effective at best and makes Canadian physicians Competing interests: None declared. operation of an N100 respirator with appear small minded. A more positive ULPA, the user must be fit-tested. The headline might have been “New federal United States and many other countries program supports compassionate care The best protection have numerous requirements for using for ill family members.” a negative-pressure air-purifying respi- he transmission of the caus- rator, including medical evaluation and Stephen Liben Ting severe acute respiratory syn- training, as well as yearly fit-testing. Director, Pediatric Palliative Care drome (SARS) appears to be by Program droplet and possibly through other John H. Lange The Montreal Children’s Hospital routes.1 Therefore, it is recommended Environmental and Occupational Health McGill University Health Centre that health care workers and others Consultant Montréal, Que. who may be exposed1 employ respira- Envirosafe Training and Consultants, tory and other personal protective Inc. Reference 1. Lai T. MDs will have to sign off on new compas- 2,3 Pittsburgh, Pa. equipment. The type of respirator sionate care applications. CMAJ 2003;168(7):886. that has typically been used by health care workers is the N95 half-mask.2,3 As References 1. Seto WH, Tsang D, Yung RWH, Ching TY, Ng 2 correctly stated by Richard Schabas, TK, Ho M, et al. Effectiveness of precautions The perils of PDAs the “N95-rated mask” is 95% filtration against droplets and contact in prevention of 4 nosocomial transmission of severe acute respira- efficient, but does this level of effi- tory syndrome (SARS). Lancet 2003;361:1519-20. ciency provide the best protection for 2. Schabas R SARS: prudence, not panic [editorial]. ast June I purchased an anesthesia CMAJ 2003;168:1232-33. those at risk of exposure? The effective- 3. Centers for Disease Control. Update: severe Ldatabase derived from a popular ness of the N95 respirator has been acute respiratory syndrome – United States, textbook and distributed by one of the 2003. MMWR Morbid Mortal Wkly Rep 2003;52: supported by a small study on preven- 357-60. software houses mentioned in the re- tion of occupational transmission of in- 4. Martyny J, Glazer CS, Newman LS. Respiratory view by Feisal Adatia and Philippe Be- 1 protection. N Engl J Med 2002;347:824-30. 1 fection. However, for work with bacte- 5. Sawicki J. Protection from chemical and biological dard. In February, one day after the rial bioaerosols and chemical and warfare. Surg Serv Manage 1999;5(Sep):11. Avail- guarantee on my handheld computer biological warfare agents, some have able: www.nbcprotection.com/new/geometarticles expired, the unit also expired. /protfromchembiowarfare.htm (accessed 2003 suggested that N95 masks are inappro- May 14). After purchasing a new unit, I per- priate5,6 because these respirators do not 6. Wake D, Bowry AC, Crook B, Brown RC. Per- formed a “hotsync” and successfully formance of respirator filters and surgical masks provide “absorbent capability” and be- against bacterial . J Aerosol Sci 1997;28: transferred all material from the old cause of the amount of mask leakage, 1311-29. handheld to the new unit, except the 7. Occupational Safety and Health Administration. which can be about 5% through the fil- Respiratory protective devices, part II. Final anesthesia database mentioned above. ter and 10% around the mask,7 even if rule. US Federal Register 1995;60:30335-98. Because the device ID of the new unit 8. Colton CE, Nelson TJ. Respiratory protection. properly fitted. For biological diseases In: DiNardi SR, editor. The occupational environ- was different from that of the old one, like SARS, for which just a few particles ment — its evaluation and control. Fairfax (VA): it was impossible to unlock and transfer may be sufficient for infection, the N95 American Industrial Hygiene Association; 1997. the program. p. 971-1000. mask may indeed be inadequate, and 9. ULPA filter. In: Glossary. 1.0 Cleanroom terminol- I telephoned the company long dis- some health care workers may there- ogy. San Carlos (CA): Servicor; [date unknown]. tance but was unable to reach a human Available: www.servicor.com/glossary.html (ac- fore become infected even if they use cessed 2003 May 16). being. My request for a return call, left the respirator properly. on the company’s voice-mail system, A better selection for respiratory Competing interests: None declared. produced no response, and I’ve had no

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