Noninvasive Mechanical Ventilation in Patients with Tuberculosis: Exhaled Breath-Generated Aerosols of Mycobacterium tub
Patients with acute exacerbation of tuberculosis can now be treated successfully with noninvasive ventilation (NIV) [1]. NIV is effective not only in cases of rapidly progressive mycobacterial tuberculosis but also in chronic cases where the disease has e
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17
Yoshinori Matsuoka
Keywords
Noninvasive mechanical ventilation • Tuberculosis • Aerosols • Mycobacterium tuberculosis
17.1
Introduction
Patients with acute exacerbation of tuberculosis can now be treated successfully with noninvasive ventilation (NIV) [1]. NIV is effective not only in cases of rapidly progressive mycobacterial tuberculosis but also in chronic cases where the disease has exacerbated. NIV use may reduce the high demand for intensive care unit (ICU) beds [2]. This is the first study to assess clinically the risk of spread of mycobacterial tuberculosis infection by droplet or aerosol during NIV.
17.2
Infection and Transmission Course of Mycobacterial Tuberculosis
Mycobacterial tuberculosis is spread by infectious droplet nuclei (airborne particles 1–5 μm in diameter) through coughing, sneezing, or vocalization by patients with pulmonary or laryngeal tuberculosis [3]. Mycobacterial tuberculosis invariably spreads through air rather than by direct contact. In other words, a susceptible individual inhales droplet nuclei containing Mycobacterium tuberculosis, following which infection is established when droplet nuclei reach the pulmonary alveoli
Y. Matsuoka, MD, PhD Department of Anesthesiology and Intensive Care Medicine, Saga Medical School Hospital, Saga City, Japan e-mail: [email protected]
A.M. Esquinas (ed.), Noninvasive Ventilation in High-Risk Infections and Mass Casualty Events, 157 DOI 10.1007/978-3-7091-1496-4_17, © Springer-Verlag Wien 2014
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Y. Matsuoka
through the upper respiratory tract. Spread of the infection in the body then occurs, first by lymphatic and then by hematogenous dissemination. The immune response appears within 2–12 weeks of the initial infection, when the immunological test becomes positive [3]. There are no restrictions on tuberculosis patients coughing, sneezing, or talking during NIV management. Thus, the formation of airborne infectious droplet nuclei is expected.
17.3
Does Aerosol Diffusion Occur in NIV?
According to Simonds, NIV is a droplet-generating procedure rather than an aerosol-generating procedure, producing droplets of >10 μm. Because of their large mass, most droplets cascade down onto nearby surfaces within an area of 1 m2. The only device used clinically to produce aerosols is the nebulizer, and its output profile is consistent with nebulizer characteristics rather than the dissemination of large droplets [4]. These findings suggest that health care workers (HCWs) providing NIV and working within 1 m2 of an infected patient should be provided a higher level of respiratory protection. Infection control measures designed to limit aerosol spread may have less relevance for this procedure. According to the findings of studies aimed at determining clinical evidence of the risk of transmission of acute respiratory infections to HCWs caring for patients undergoing aerosol-generating procedures, some procedures that are potentially capable of generating aerosols are associated with increased risk of acute respiratory infection transm
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