Isolation of those ill with contagious disease has been a fundamental infection control concept for hundreds of years. However, recent studies suggest that fewer than 50% of health—care workers comply with their hospitals' isolation precaution policies and that efficacy of some of those policies is questionable. In response, two new systems, based upon fundamentally different goals, were promoted. The Centers for Disease Control, prompted by health—care worker& concerns about occupational risk of human immunodeficiency virus (HIV) from a growing number of patients with acquired immunodeficiency disease syndrome (AIDS), issued formal guidelines in 1987. This formed the basis for Universal Precautions (UP), a unifying strategy for precautions with all patients regardless of diagnosis intended to reduce risk to hospital staff members. Also in 1987, one hospital issued guidelines for Body Substance Isolation (BSI), hygienic precautions to be used with all patients based on recognition that colonized body substances are important reservoirs for cross—infection to both patients and staff members. These new strategies have been promoted widely, but there have been no formal assessments to reconcile controversies they raised nor to confirm their effectiveness. Further, necessary assessment tools have not been validated. This thesis provides new tools and new information to address three vital questions: Have hospitals adopted Universal Precautions or Body Substance Isolation? Do their staff members use the new system of precautions in daily practice? Has reliable use of a new system led to decreased risk of infection? A confidential mailed survey of all acute—care Canadian hospitals was conducted to measure rates of guideline receipt and adoption. It also obtained information on motivations for and perceived effectiveness of strategies adopted. A self—selected group of responding hospitals subsequently participated in standardized covert observation of their nurses infection control practices, then had the observed nurses complete a test examining their knowledge and beliefs. Employee health records were also examined to determine whether needlestick injury rates had changed since adoption of a new infection control strategy. Most Canadian hospitals adopted and modified new strategies based upon reasonable but unproven extensions of logic to protect health—care workers from HIV. 74% claimed UP (65%) or BSI (9%) but only 5% of 359 claiming UP and 0 of 50 claiming BSI adopted all policies expected. Many hospitals had not received key guideline publications. Guideline source, hospital size, and other variables were significantly associated with receipt. Nurses in 35 hospitals were observed to wear gloves during only z60% of procedures in which gloving was expected; rates varied widely among hospitals. Direct examination of sharps disposal containers confirmed compliance with a policy to not recap used needles (taken as recapping rate of 25%) in only 47% of 32 hospitals. Paired analysis of needlestick injury rates in 11 hospitals during comparable 90—day periods before versus after implementing UP/BSI showed no significant difference. 489 nurses completing a written test achieved their highest scores and least discordance among questions regarding procedural issues established long before UP/BSI, and lower scores or greater discordance on UP/BSJ concepts of philosophy, risk recognition and newer procedures. Positive correlation between knowledge and practice was not evident. UP and BSI now mean different things in different hospitals and have not been effective in harmonizing health—care workers’ infection control practices. Carefully standardized assessment methods are needed to guide their evolution to cost—effectiveness.

Isolation of those ill with contagious disease has been a fundamental infection control concept for hundreds of years. However, recent studies suggest that fewer than 50% of health—care workers comply with their hospitals' isolation precaution policies and that efficacy of some of those policies is questionable. In response, two new systems, based upon fundamentally different goals, were promoted. The Centers for Disease Control, prompted by health—care worker& concerns about occupational risk of human immunodeficiency virus (HIV) from a growing number of patients with acquired immunodeficiency disease syndrome (AIDS), issued formal guidelines in 1987. This formed the basis for Universal Precautions (UP), a unifying strategy for precautions with all patients regardless of diagnosis intended to reduce risk to hospital staff members. Also in 1987, one hospital issued guidelines for Body Substance Isolation (BSI), hygienic precautions to be used with all patients based on recognition that colonized body substances are important reservoirs for cross—infection to both patients and staff members. These new strategies have been promoted widely, but there have been no formal assessments to reconcile controversies they raised nor to confirm their effectiveness. Further, necessary assessment tools have not been validated. This thesis provides new tools and new information to address three vital questions: Have hospitals adopted Universal Precautions or Body Substance Isolation? Do their staff members use the new system of precautions in daily practice? Has reliable use of a new system led to decreased risk of infection? A confidential mailed survey of all acute—care Canadian hospitals was conducted to measure rates of guideline receipt and adoption. It also obtained information on motivations for and perceived effectiveness of strategies adopted. A self—selected group of responding hospitals subsequently participated in standardized covert observation of their nurses infection control practices, then had the observed nurses complete a test examining their knowledge and beliefs. Employee health records were also examined to determine whether needlestick injury rates had changed since adoption of a new infection control strategy. Most Canadian hospitals adopted and modified new strategies based upon reasonable but unproven extensions of logic to protect health—care workers from HIV. 74% claimed UP (65%) or BSI (9%) but only 5% of 359 claiming UP and 0 of 50 claiming BSI adopted all policies expected. Many hospitals had not received key guideline publications. Guideline source, hospital size, and other variables were significantly associated with receipt. Nurses in 35 hospitals were observed to wear gloves during only z60% of procedures in which gloving was expected; rates varied widely among hospitals. Direct examination of sharps disposal containers confirmed compliance with a policy to not recap used needles (taken as recapping rate of 25%) in only 47% of 32 hospitals. Paired analysis of needlestick injury rates in 11 hospitals during comparable 90—day periods before versus after implementing UP/BSI showed no significant difference. 489 nurses completing a written test achieved their highest scores and least discordance among questions regarding procedural issues established long before UP/BSI, and lower scores or greater discordance on UP/BSJ concepts of philosophy, risk recognition and newer procedures. Positive correlation between knowledge and practice was not evident. UP and BSI now mean different things in different hospitals and have not been effective in harmonizing health—care workers’ infection control practices. Carefully standardized assessment methods are needed to guide their evolution to cost—effectiveness. / Graduate and Postdoctoral Studies / Graduate

According to recommendations from the Facility Guidelines Institute (FGI) of the American Institute of Architects (AIA), World Health Organization (WHO) and Center for Disease Control and Prevention (CDC), a common engineering approach to isolation room design is to maintain the air ventilation rate at a minimum of 12 air changes per hour (ACH) for mixing and dilution, and a negative pressure in the room to direct airflow inwards, instead of leaking outwards. / In collaborations with physicians in the Respiratory Division and the Intensive Care Unit (ICU) at the Chinese University of Hong Kong (CUHK), a series of experiments were carried out to verify the ventilation performance of an All room at the Princess Margaret Hospital (PMH). Experiments investigated the effects of ACH, the control of airflow direction, the air tightness of the automatic swing door and the application of positive pressure ventilation procedures, such as high flow rate oxygen masks, jet nebulizers and NPPV. These were extensively tested in two different isolation rooms of the Prince of Wales Hospital (PWH) and PMH, under common clinical circumstances and environmental conditions. / Many patients with severe respiratory infection require supportive therapy for respiratory failure. Common interventions involve supplemental oxygen to improve tissue oxygenation. In the worst scenario, mechanical ventilation via non-invasive positive pressure ventilation (NPPV) may be required. Since a large amount of aerosols is generated during these interventions, there is a great risk of spreading infectious aerosols from the respiratory tract of the patient to the surrounding environment. / The aerodynamic data in this thesis infonns architects and engineers on how to improve the hospital ward ventilation design so as to avoid aerosol and ventilation leakage. Ultimately, it is hoped that this work may play a role in preventing devastating nosocomial outbreaks in the future. / The design of airborne infection isolation (AII) room has become one of the major research domains following the emergence of the global concern of acute respiratory diseases in this century. These include severe acute respiratory syndrome (SARS) in 2003, H5N1 avian influenza, and pandemic influenza H1N1 in 2009. All of which have claimed thousands of lives. Even with the current stringent design and practice guidelines, nosocomial infection of healthcare workers (HCWs) and inpatients continues to occur. This implies that there might be limitations in current isolation ward designs. / The experiments implemented a high-fidelity human patient simulator (HPS) which could be programmed with different lung breathing conditions and oxygen flow rate settings. The patient exhaled air dispersion distances and airflow patterns were captured in detail with a non-intrusive, laser light sheet, smoke particle scattering technique, designed for this thesis. Thin laser light sheets were generated by a high energy YAG laser with custom cylindrical optics. Smoke concentration in the patient exhaled air and leakage jets was estimated from the intensity of light scattered, which was then expressed as nonnalized particle concentration contours using computer programs developed for this study. / The study quantitatively revealed the distinctive patient exhaled airflow patterns and the extent of bioaerosol, generated directly from the patient source with the application of different oxygen delivery interventions for different patient lung conditions and oxygen flow rates. It was found that contamination was more critical during the administration of oxygen therapies, which is common in clinical circumstances. Source control is therefore the most efficient and effective approach to the reduction and even elimination of patient exhaled bioaerosol contaminants. Thus, when working in an isolation room environment, full preventive measure should be taken and it is essential to consider the location of mechanical vents and the patient exhaled airflow patterns. It has also been shown in experiment that applications of bacterial viral filter could be a solution to the problem. / Chow, Ka Ming. / Advisers: Puay Peng Ho; Jin Yeu Tsou. / Source: Dissertation Abstracts International, Volume: 73-09(E), Section: A. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 115-147). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.