ABSTRACT
Due to the COVID19 outbreak, there has been increasing interest in tailoring, modifying and improving conventional personal protective equipment to increase their service life and make them more effective against viruses and bacteria. Here, atomic layer deposition (ALD) was used to functionalize the filter of N95 mask with nano-islands of silver. X-ray photoelectron spectroscopy and x-ray absorption fine structure were used for ALD silver characterization; microbiological assay was conducted to study the effectiveness of the deposited silver against the air-borne pathogen Staphylococcus aureus (S. aureus). Results showed that silver ALD successfully functionalized the N95 mask at 90 and 120 °C for two different numbers of ALD cycles (1100 and 1500 cycles). The deposited silver nano-islands were stable on the N95 filter media against washing. The leaching of silver nano-islands was studied using inductively coupled plasma mass spectrometry of phosphate-buffered saline solution after soaking the mask in it over predetermined times. <9% of Ag was removed after a maximum time of 4 h that was investigated. Antimicrobial tests showed that for samples functionalized with 1100 ALD cycles of Ag, 76% reduction in S. aureus colony-forming units content was observed after 24 h of biofilm development on the mask surfaces.
ABSTRACT
Background: Persistent symptoms after the acute SARS-CoV-2 infection are referred to as post-COVID-19 syndrome(PCS). Fatigue, palpitations and exercise intolerance are common complains among PCS patients in whom unexplained sinus tachycardia is a frequent observation. Objective: To evaluate the prevalence and the pathophysiological mechanisms of IST in a consecutive and prospective population of patients with PCS. Methods: Consecutive patients with persistent symptoms 3 months after an acute COVID-19 were prospectively evaluated at a multi-disciplinary PCS unit. All patients were screened for IST and those with confirmed criteria underwent comprehensive CV examination: ECO, 24h Holter (assessment of the cardiac autonomic function), QoL Questionnaire (MLHFQ), six-min walking test (6MWT) and blood sample with inflammation and myocardial biomarkers. Two control patients, matched by age and gender, were assigned to each case: one with previous SARS-CoV-2 infection without PCS (group 2,recovered asymptomatic) and one without prior COVID (group 3,uninfected). Results: IST were met in 43/200 PCS patients (21%) being more common in young (mean age 39y) woman (91%) without clinical history and with mild COVID (not requiring hospital admission during the acute phase). Mean HR 96±3 (supine) and 112±17 (upright position), with 8 patients fulfilling diagnostic of POTS. No underlying structural heart disease, proinflammatory state, myocyte injury or hypoxia were identified 6MWT showed a significantly diminished exercise capacity(59% of the estimated distance). An impaired QoL was also identified. Regarding the 24h Holter, all HRV parameters were significantly deteriorated in IST patients compared with control groups (significantly decrease in time and frequency domain parameters). The most reduced components were those related with the cardiovagal tone: PNN50 4±4 in group 1 (vs 11±9 in group 2 and 18±9 in group 3;p<0 002);HF band 336±280 (vs 823±1200 in group 2 and 1229±630 in group 3;p=0 01). Conclusion: IST is a prevalent condition among PCS patients and may at least partially explain the prevalent symptoms of fatigue, impaired exercise, and palpitations, Cardiac ANS imbalance with decreased parasympathetic activity may account as a plausible explanation.
ABSTRACT
Background: Persistent symptoms after the acute phase of SARS-CoV-2 infection are referred to as 'post-COVID-19 syndrome' (PCS), with a reported incidence ranging between 35% and 87%. Fatigue, palpitations and exercise intolerance are common complains among PCS patients in whom unexplained sinus tachycardia, occasionally exacerbated by postural changes, is a frequent observation that remains poorly characterized. Purpose: We sought to characterize the prevalence of inappropriate sinus tachycardia (IST) and postural orthostatic tachycardia (POTS) in a consecutive and prospective population of patients with PCS. Methods: Consecutive patients with persistent symptoms 3 months after an acute SARS-CoV-2 infection were prospectively evaluated at a multi-disciplinary PCS unit. All patients were screened for IST or POTS and those with confirmed criteria underwent comprehensive cardiovascular examination including echocardiography, 24-hour Holter, Minnesota Living with Heart Failure Questionnaire (MLHFQ), six-minute walking test (6MWT) and inflammation and myocardial biomarkers. Two control patients, matched by age and gender, were assigned to each case: one with previous SARS-CoV-2 infection without PCS (group 2) and one without prior SARS-CoV-2 infection (group 3). Results: IST or POTS criteria were met in 34 out of the 200 PCS patients (17%). The mean age was 39 ± 10 years, with 29 women (91%). The interval from the index COVID-19 disease to the PCS diagnosis was 71 ± 17 days, with a majority of patients (n = 29,85%) not requiring hospital admission during the acute phase. At physical examination, the mean heart rate was 96 ± 3bpm at supine and 112 ± 17bpm at the upright position, with 8 patients fulfilling diagnostic criteria of POTS. No underlying structural heart disease, pro-inflammatory state, myocyte injury or hypoxia were identified among our patient population. The 6MWT showed a significantly diminished exercise capacity with a 59% of the estimated distance after adjustment by age, sex and body mass index;an impaired quality of life was also identified, as suggested by a median MLFHQ total score of 67 out of 105 points. The 24-hour Holter showed an increase in HR predominantly during daytime in group 1 (mean daytime HR of 94 ± 3bpm), an altered heart rate variability with a decrease in time domain parameters [PNN50 4 ± 4 in group 1 (vs. 11 ± 9 in group 2 and 18 ± 9 in group 3;p < 0.002)respectively;SD 100 ± 20 (vs. 127 ± 38 and 136 ± 13;p = 0.009) and a decrease in frequency domain parameters [LF 751 ± 450 (vs. 1721 ± 1009 and 2199 ± 920;p = 0.01), HF 336 ± 280 (vs. 823 ± 1200 and 1229 ± 630;p = 0.01)]. Conclusions: IST and its POTS variant are a prevalent condition among PCS patients and may at least partially explain the common symptoms of fatigue, impaired exercise and palpitations that characterize the PCS. Cardiac autonomic nervous system imbalance may account as a plausible pathophysiological mechanism of IST in PCS patients.