key: cord-0007707-3kik7o5i authors: Zhang, Y. title: High justification for universal stringent precautions in lung function testing date: 2005-01-26 journal: Respir Med DOI: 10.1016/j.rmed.2004.12.003 sha: 66de2b5caee40175a96e5aab424a22fa79af94e0 doc_id: 7707 cord_uid: 3kik7o5i nan I read with great interest the recent review article by Kendrick et al. 1 regarding infection control in lung function (LF) equipment. I share the authors' view that ''There is clear evidence that respiratory equipment becomes contaminated with microorganisms of probable respiratory tract origin during use'' and their view that ''there is a need for clear procedures to be in place to reduce possible risks to a realistic minimum.'' I agree with some of their recommendations, such as the referring clinicians should complete an LF testing request form for each patient with questions relating to the patient's infection and immunity status; the patients with known infections are tested at the end of the day or in their own rooms. However, I do not agree with some of their other views and recommendations: 1. I disagree with the authors' view that for the majority of patients, there will be no significant risk of cross-infection from having LF tests. 1 Chronically ill patients and elderly persons (65years old or over) are susceptible to respiratory infections 2 and should be considered as high-risk subjects to cross-infection in LF tests. 4 Also, it is impractical to test each patient for all infectious diseases before LF testing. Therefore, universal stringent precautions for everyone in LF tests are really needed and highly justified. In 1991, the head author of the recent article clearly recommended, based on the theory of rationales, that ''Breathing circuits: All testing equipment that comes into direct or close contact with mucous membranes, i.e. mouthpieces, pneumotachographs, tubing and rebreathing valves, should be disinfected before use on other patients.'' 5 However, the recent article states: ''Breathing circuits: in practice, disinfection at the end of each day, rather than between each patient should be sufficient.'' 1 I would like to question the head author's reasons why the previous recommendation with universal high-level measure for breathing circuits has been significantly downgraded, despite the fact that the incidence of infectious diseases has been increasing in recent years. 3. Respiratory viral infections, which may be easily transmitted by infected aerosols, account for significant mortality and morbidity. Much smaller doses of viruses than that of bacteria may cause respiratory infections. 6 The authors of the recent article only list one respiratory virus (rhinovirus) and do not mention other important respiratory viruses, such as influenza virus, respiratory syncytial virus, and severe acute respiratory syndrome (SARS)-associated coronavirus that suddenly and lethally attacked people around the world without warning in 2003 and remains a severe threat. In addition, the authors consider the cross-infection of a common cold as only causing inconvenience to patients. In fact, to healthy people it may cause substantial discomfort, absenteeism and economic losses; 3 to patients with asthma or COPD, it may cause severe exacerbations and complications. I believe that, any preventable cross-infection acquired from LF testing is not acceptable. 4. Some recommendations in the recent article are substandard. For exercise testing breathing circuits (Hans Rudolf valves), it states: ''Dismantling, washing in hand-hot soapy water, rinsing and drying should be sufficient to ensure adequate cleaning and disinfection.'' 1 I would like to question the authors the scientific basis and the efficiency of this disinfection method. A study, which used an insensitive sampling method described by the head and the third authors, 7 found that 13% of the samples from a heated pneumotachograph were contaminated. But in the recent article, the authors only recommend ''minimal cleaning''. 1 5. One recommendation in the recent article is impractical and inefficient. In Table 3 , the recommendation of disinfection for breathing circuits shows: ''Patient valves-clean between patients with alcohol wipes.'' 1 (It implies that the authors are concerned over the contamination of the proximal rebreathing parts of LF equipment between patients.) But the disadvantages of alcohol wipe, as pointed out by the authors in Table 1 , 1 are that valves and flow sensors cannot be decontaminated thoroughly by this method (parts of them easily missed). 6. The authors recommend high-level precautions for peak flow meter: ''either a one-way valve mouthpiece or a new barrier filter should be used for each patient.'' 1 On the other hand, they consider that the routine use of filters in LF tests is difficult to justify due to cost constraints, 1 which is not consistent with the former recommendation. Good quality barrier filters with high filtration efficiency, low air resistance and small dead space have been available for at least 5 years. The main advantage of applying singleuse high-efficient filters in LF testing is that they can protect: (a) breathing circuits, especially flow sensors from contamination with droplets of saliva and mucus, 8 which may contain microorganisms and induce test errors; (b) patients from inhaling pathogens from the breathing circuits; (c) the air of the surrounding area from contaminated aerosols, hence the technical staff and the patients. I believe, the universal use of single-use filters is actually very reasonable and cost-effective, and can reduce the cross-infection risks during LF tests into a realistic minimum. The barrier filters can also act as mouthpieces and may significantly reduce the costs for disinfection, and for replacement of breathing circuits worn by disinfectants. Indeed, the cost of a high-efficient filter for LF testing is very little in many developed countries. Now in Australia, it costs only AU$ 2.00-2.50 each, being about twenty times lower than the cost of a flu vaccination for a person. With the cooperation of the world experts to verify and unify barrier filters, their costs can be dramatically reduced by mass production, and can be made affordable to the developing countries. Moreover, with the application of media-changeable filters (every filter case being disinfected after each patient use), the costs can be further cut by half. The World Health Report 2003 by WHO 9 points out that: ''New diseases have been emerging at the unprecedented rate of one a year for the last two decades, and this trend is certain to continue.'' In the first half of 2003, SARS posed a particularly serious threat to people's health. Its initial symptoms were non-specific and common, and maximum incubation period, estimated at 10 days, allowed international spread by air travel. SARS also caused widespread social disruption and huge economic losses (estimated US$ 30 billion loss in the Far East alone). 10 One of the lessons learnt from SARS outbreaks, pointed out in the WHO 2003 annual report, is that ''weaknesses in health systems can permit emerging infections to amplify and spread, and can compromise patient care. The strengthening of health systems thus deserves high priority.'' 9 I believe that, we should rigorously prevent the spread of the exiting infectious diseases and should be well prepared against the recurrence of SARS and the emergence of new highly infectious diseases, including the next influenza pandemic. Therefore, we should implement upgraded and strengthened precautions for all the patients undergoing LF tests. Until now, applying singleuse high-efficient filters followed by regularly disinfecting respiratory circuits is the most prac-tical and effective approach to prevent crossinfection in LF tests. Infection control of lung function equipment: a practical approach Respiratory viral infections in adults How do we catch colds? Impact of sputum bacteria on airway inflammation and health status in clinical stable COPD Infection control procedures in UK laboratories: survey and recommendations. Infection control yearbook 1991 Viral Infections Bacterial colonization as a potential source of nosocomial respiratory infections in spirometers Using barrier filters to protect spirometer sensors from droplet deposition World Health Organization. The world health report Severe acute respiratory syndrome (SARS): status of the outbreak and lessons for the immediate future