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The guidelines on severe acute respiratory syndrome (SARS) published by the British Infection Society (BIS) and the British Thoracic Society (BTS) in July 2003 recommend giving adult patients with suspected or probable SARS an N95 or equivalent mask and request that they wear this continuously.1 This recommendation was apparently provided to prevent the spread of the SARS coronavirus from the patient to the surrounding environment.
An N95 respirator (mask) is a negative pressure respirator which only filters air entering the mask, not leaving it.2 Those wearing this respirator will experience an additional burden on the breathing system in moving air in and out of the respirator.3 For this reason, occupational protection agencies such as the United States Occupational Safety and Health Administration4 require those using these types of respirator to be medically qualified because of physiological3 and psychological5 stresses that may occur. Patients with SARS coronavirus will certainly not meet these requirements and use of a respirator will only add to their pulmonary stress. Since there will be no filtration of air leaving the wearer of this respirator, little protection besides that of a barrier will occur, allowing viral spread from the patient with limited impedance. It has also been suggested6 that N95 respirators, even when properly used by healthcare workers, do not provide adequate protection against the SARS virus.
The recommendation should be changed to eliminate the requirement of the patient using a respirator and instead shifting this requirement to healthcare workers. This will provide the best protection against the spread of SARS coronavirus. It has recently been suggested7 that a high ventilation rate in hospital wards with SARS patients results in lower infectivity of healthcare workers. The most adequate form of protection is therefore proper use of personal protective equipment, including respirators, by healthcare workers together with a high ventilation rate.6 The guidelines should be adjusted to recommend that patients should not wear a respirator.
We thank Mr Lange for his comments on the BTS/BIS SARS guidelines of July 2003. He and other Thorax readers will be pleased to know that the guidelines have been rewritten over the last few months and are now on the BTS website under the title “Hospital management of adults with SARS if SARS re-emerges”.1
The new BTS/BIS/HPA guidelines recommend that all possible or probable SARS patients should wear a surgical face mask rather than an N95 respirator, and that healthcare workers should wear a respirator complying with the European standard EN149:2001 FFP3 or higher filtration. Healthcare workers should note that wearing a respirator is just one way of preventing the spread of SARS; other important precautions include good personal hygiene (especially hand hygiene) and gloves, aprons, gowns, visors, and goggles when appropriate.2 For further up to date information please visit the UK Health Protection Agency (HPA) website.3
The UK Health Protection Agency continues to urge healthcare workers to remain vigilant to the possibility of SARS even though the level of risk in the UK remains very low.