Modeling of nursing care-associated airborne transmission of SARS-CoV-2 in a real-world hospital setting.

Respiratory transmission of SARS-CoV-2 from one older patient to another by airborne mechanisms in hospital and nursing home settings represents an important health challenge during the COVID-19 pandemic. However, the factors that influence the concentration of respiratory droplets and aerosols that potentially contribute to hospital- and nursing care-associated transmission of SARS-CoV-2 are not well understood. To assess the effect of health care professional (HCP) and patient activity on size and concentration of airborne particles, an optical particle counter was placed (for 24 h) in the head position of an empty bed in the hospital room of a patient admitted from the nursing home with confirmed COVID-19. The type and duration of the activity, as well as the number of HCPs providing patient care, were recorded. Concentration changes associated with specific activities were determined, and airway deposition modeling was performed using these data. Thirty-one activities were recorded, and six representative ones were selected for deposition modeling, including patient's activities (coughing, movements, etc.), diagnostic and therapeutic interventions (e.g., diagnostic tests and drug administration), as well as nursing patient care (e.g., bedding and hygiene). The increase in particle concentration of all sizes was sensitive to the type of activity. Increases in supermicron particle concentration were associated with the number of HCPs (r = 0.66; p < 0.05) and the duration of activity (r = 0.82; p < 0.05), while submicron particles increased with all activities, mainly during the daytime. Based on simulations, the number of particles deposited in unit time was the highest in the acinar region, while deposition density rate (number/cm2/min) was the highest in the upper airways. In conclusion, even short periods of HCP-patient interaction and minimal patient activity in a hospital room or nursing home bedroom may significantly increase the concentration of submicron particles mainly depositing in the acinar regions, while mainly nursing activities increase the concentration of supermicron particles depositing in larger airways of the adjacent bed patient. Our data emphasize the need for effective interventions to limit hospital- and nursing care-associated transmission of SARS-CoV-2 and other respiratory pathogens (including viral pathogens, such as rhinoviruses, respiratory syncytial virus, influenza virus, parainfluenza virus and adenoviruses, and bacterial and fungal pathogens).

Health effects of cigarettes, electronic cigarettes and waterpipes / A cigaretta, az elektromos cigaretta és a vízipipa egészségre gyakorolt hatása.

Összefoglaló. A dohányzás káros hatásainak vizsgálata hosszú ideje az orvostudomány egyik legintenzívebben kutatott területe. A nagy tudományos érdeklodésnek köszönhetoen ma már meggyozo evidenciák állnak rendelkezésre a hagyományos cigaretta használatának számos negatív hatásáról. Ezzel ellentétben a sokkal késobb bevezetett helyettesíto termékek veszélyeirol lényegesen kevesebbet tudunk. E körbe tartozik a manapság egyre népszerubb elektromos cigaretta is, amelyre egyre több, egészségügyi kockázatot felméro munka fókuszál. Ugyanakkor a több évszázados múltra visszatekinto és a világ bizonyos helyein sokáig népszeru vízipipa érdekes esetnek számít, mivel használóinak száma a nyugati világban az utóbbi idoben megugrott, de az emberre gyakorolt hatása számos ponton még vita tárgyát képezi. A jelen munka célja, hogy a hazai és a nemzetközi szakirodalom alapján feltérképezze a hagyományos cigaretta, az elektromos cigaretta és a vízipipa fontosabb egészségügyi hatásait, és rámutasson azokra a kapcsolódó területekre, ahol további kutatások szükségesek. A szakirodalmi áttekintés során a különbözo publikációs adatbázisokban fellelheto tudományos cikkeket elemeztük. A megvizsgált szakirodalom alapján a tartós dohányzásnak bizonyítottan a szív-ér rendszert és a légzorendszert károsító hatása van, de növekvo számú bizonyíték utal a neurológiai káros hatásokra és a gasztroenterológiai hatásokra is. Ugyanakkor az elektromos cigaretta és a vízipipa esetében a bizonyított akut hatások mellett a hosszú távú hatásokat illetoen további intenzív kutatásokra van szükség. Az elektromos cigaretta és a vízipipa esetében a hosszú távú hatások kapcsán a meggyozo evidencia hiánya semmiképpen nem jelenti azt, hogy ezen termékeket kockázatmentesnek kellene tekinteni, sot a pulmonológusoknak és a döntéshozóknak mindent meg kell tenniük annak érdekében, hogy valamennyi dohánytermék törvényi szabályozása azok használatának visszaszorítását célozza. A kérdés fontosságának a COVID-19-pandémia különös aktualitást ad. Orv Hetil. 2021; 162(3): 83-90. Summary. Revealing the health effects associated with smoking has been in the focus of intense research for decades. Due to these research efforts, there is a convincing evidence regarding the negative effects of conventional cigarettes. However, much less is known about the replacement products such as electronic cigarettes. Moreover, the effects of waterpipes are also not fully explored, in spite of their long history. The scope of the present work is to survey the open literature to map the knowledge related to the health effects of conventional cigarettes, e-cigarettes and waterpipes. The analysis of the related scientific literature was performed based on papers retrieved in large publication repositories. Based on the reviewed literature, long-term smoking has demonstrated adverse effects on the respiratory as well as the heart and circulatory systems. In addition, the correlation between cigarette smoking and some gastroenterological and neurological diseases is also increasingly evident. By the same token, though the acute effects of e-cigarette and waterpipe are well documented, the protracted effects are still to be explored. The lack of pertinent information regarding the late effects of e-cigarette and hookah does not imply that there is no health risk associated with their consumption. On the contrary, in addition to the regular antismoke measures, pulmonologists and policy makers should do everything to lower the consumption of these alternative products. Orv Hetil. 2021; 162(3): 83-90.

Deposition distribution of the new coronavirus (SARS-CoV-2) in the human airways upon exposure to cough-generated droplets and aerosol particles.

The new coronavirus disease 2019 (COVID-19) has been emerged as a rapidly spreading pandemic. The disease is thought to spread mainly from person-to-person through respiratory droplets produced when an infected person coughs, sneezes, or talks. The pathogen of COVID-19 is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It infects the cells binding to the angiotensin-converting enzyme 2 receptor (ACE2) which is expressed by cells throughout the airways as targets for cellular entry. Although the majority of persons infected with SARS-CoV-2 experience symptoms of mild upper respiratory tract infection, in some people infections of the acinar airways result in severe, potentially fatal pneumonia. However, the induction of COVID-19 pneumonia requires that SARS-CoV-2 reaches the acinar airways. While huge efforts have been made to understand the spread of the disease as well as the pathogenesis following cellular entry, much less attention is paid to how SARS-CoV-2 from the environment reach the receptors of the target cells. The aim of the present study is to characterize the deposition distribution of SARS-CoV-2 in the airways upon exposure to cough-generated droplets and aerosol particles. For this purpose, the Stochastic Lung Deposition Model has been applied. Particle size distribution, breathing parameters supposing normal breathing through the nose, and viral loads were taken from the literature. We found that the probability of direct infection of the acinar airways due to inhalation of particles emitted by a bystander cough is very low. As the number of viruses deposited in the extrathoracic airways is about 7 times higher than in the acinar airways, we concluded that in most cases COVID-19 pneumonia must be preceded by SARS-CoV-2 infection of the upper airways. Our results suggest that without the enhancement of viral load in the upper airways, COVID-19 would be much less dangerous. The period between the onset of initial symptoms and the potential clinical deterioration could provide an opportunity for prevention of pneumonia by blocking or significantly reducing the transport of viruses towards the acinar airways. Therefore, even non-specific treatment forms like disinfection of the throat and nasal and oral mucosa may effectively keep the viral load of the upper airways low enough to avoid or prolong the progression of the disease. In addition, using a tissue or cloth in order to absorb droplets and aerosol particles emitted by own coughs of infected patients before re-inhalation is highly recommended even if they are alone in quarantine.

The effect of oral and nasal breathing on the deposition of inhaled particles in upper and tracheobronchial airways.

The inhalation route has a substantial influence on the fate of inhaled particles. An outbreak of infectious diseases such as COVID-19, influenza or tuberculosis depends on the site of deposition of the inhaled pathogens. But the knowledge of respiratory deposition is important also for occupational safety or targeted delivery of inhaled pharmaceuticals. Simulations utilizing computational fluid dynamics are becoming available to a wide spectrum of users and they can undoubtedly bring detailed predictions of regional deposition of particles. However, if those simulations are to be trusted, they must be validated by experimental data. This article presents simulations and experiments performed on a geometry of airways which is available to other users and thus those results can be used for intercomparison between different research groups. In particular, three hypotheses were tested. First: Oral breathing and combined breathing are equivalent in terms of particle deposition in TB airways, as the pressure resistance of the nasal cavity is so high that the inhaled aerosol flows mostly through the oral cavity in both cases. Second: The influence of the inhalation route (nasal, oral or combined) on the regional distribution of the deposited particles downstream of the trachea is negligible. Third: Simulations can accurately and credibly predict deposition hotspots. The maximum spatial resolution of predicted deposition achievable by current methods was searched for. The simulations were performed using large-eddy simulation, the flow measurements were done by laser Doppler anemometry and the deposition has been measured by positron emission tomography in a realistic replica of human airways. Limitations and sources of uncertainties of the experimental methods were identified. The results confirmed that the high-pressure resistance of the nasal cavity leads to practically identical velocity profiles, even above the glottis for the mouth, and combined mouth and nose breathing. The distribution of deposited particles downstream of the trachea was not influenced by the inhalation route. The carina of the first bifurcation was not among the main deposition hotspots regardless of the inhalation route or flow rate. On the other hand, the deposition hotspots were identified by both CFD and experiments in the second bifurcation in both lungs, and to a lesser extent also in both the third bifurcations in the left lung.