ABSTRACT
The airborne transmission of SARS-CoV-2 has been quickly suggested based on the stability of SARS-CoV-2 in aerosol for 3 hours. Nebulization, by a possible microorganisms contamination and/or by the aerosolization of contaminated particles, may expose health care workers. Thus, various guidelines on nebulization emerged during the SARS-CoV-2 pandemic to ensure a maximal protection. This study aimed to address the risk of airborne transmission in patients hospitalized with severe COVID-19. Ten severe COVID-19 patients were recruited at the admission in the hospital. They were treated by nebulization with a standard single-use jet nebulizer operating at 8 L/min with a T piece connected to a mouthpiece and a filter. Immediately after the first nebulization, the residual solution of each nebulizer was sampled. Then, the nebulizers were refilled with isotonic saline solution to complete the residual volume. The filter was replaced by a BioSampler (SKC 20-mL) loaded with 20 mL phosphatebuffered saline and 0.5% bovine serum albumin. The nebulizer was driven by a compressed air supply, and a 10minnebulization was performed again on the bench. The emitted aerosol was continuously collected during the nebulization. The nominal and emitted dose were sampled. The SARS-CoV-2 viral load was quantified in all samples by RT-PCR. No SARS-CoV-2 RNA was found in any sample for all nebulizations. The result of this study shows no SARS-CoV-2 nebulizers contamination by COVID-19 patients at hospital and does not support the role of nebulizers in terms of aerosol virus dissemination in air. Nevertheless, exhaled virus by the patient itself remains and must be considered independently to the nebulizer.
ABSTRACT
Oxygenation through High Flow Delivery Systems (HFO) is described as capable of delivering accurate FiO2. Meanwhile, peak inspiratory flow [Formula: see text] ) of patients with acute hypoxemic respiratory failure can reach up to 120 L/min, largely exceeding HFO flow. Currently, very few data on the reliability of HFO devices at these high [Formula: see text] are available. We sought to evaluate factors affecting oxygenation while using HFO systems at high [Formula: see text] in a bench study. Spontaneous breathing was generated with a mechanical test lung connected to a mechanical ventilator Servo-i®, set to volume control mode. Gas flow from a HFO device was delivered to the test lung. The influence on effective inspired oxygen fraction of three parameters (FiO2 0.6, 0.8, and 1, [Formula: see text] from 28 to 98.1 L/min, and HFO Gas Flows from 40 to 60 L/min) were analyzed and are reported. The present bench study demonstrates that during HFO treatment, measured FiO2 in the lung does not equal set FiO2 on the device. The substance of this variation (ΔFiO2) is tightly correlated to [Formula: see text] (Pearson's coefficient of 0.94, p-value < 0.001). Additionally, set FiO2 and Flow at HFO device appear to significatively affect ΔFiO2 as well (p-values < 0.001, adjusted to [Formula: see text] ). The result of multivariate linear regression indicates predictors ([Formula: see text] , Flow and set FiO2) to explain 92% of the variance of delta FiO2 through K-Fold Cross Validation. Moreover, adjunction of a dead space in the breathing circuit significantly decreased ΔFiO2 (p < 0.01). The present bench study did expose a weakness of HFO devices in reliability of delivering accurate FIO2 at high [Formula: see text] as well as, to a lesser extent, at [Formula: see text] below equivalent set HFO Flows. Moreover, set HFO flow and set FIO2 did influence the variability of effective inspired oxygen fraction. The adjunction of a dead space in the experimental set-up significantly amended this variability and should thus be further studied in order to improve success rate of HFO therapy.
Subject(s)
Cannula , Respiratory Insufficiency , Adult , Humans , Oxygen , Oxygen Inhalation Therapy , Reproducibility of Results , Respiratory Insufficiency/therapyABSTRACT
Nebulization is a drug delivery mode whose prescription and application remain uncertain. A guide to good practice has been proposed by the work group on aerosol therapy of the French Society for Respiratory Diseases, so-called GAT. The previous recommendations date from 2007. In addition to an update of data on nebulization, these expert recommendations aim to be of real help to the prescriber.
Subject(s)
Drug Delivery Systems , Nebulizers and Vaporizers , Administration, Inhalation , Aerosols , HumansABSTRACT
Background: Patients with coronavirus disease (COVID-19) can develop severe hypoxemia. Meeting the soaring demands of oxygen may be a challenge. Objective: To test the efficacy of an easily handmade system, the double-trunk mask (DTM), in reducing oxygen consumption while maintaining patient's oxygenation level. Methods: Hospitalized adults with COVID-19 and hypoxemia treated with low-flow oxygen therapy we recruited. The standard oxygen delivery system was replaced by the DTM with nasal cannula for 30 minutes with an oxygen output adapted to maintain an identical oxygen saturation by pulse oximetry. The standard oxygen delivery system was then reinstated for 30 minutes. Primary outcome was the absolute change in oxygen flow between the standard delivery systems and the DTM. Secondary outcomes were changes in blood gases, vital parameters and patient comfort. Results: Eleven patients were analyzed (mean age 61 years;27% male). Compared with standard delivery systems, the oxygen output was significantly reduced with the DTM (median, 5 vs 1.5 L/min (95% CI -4 to -1.5, p=0.003)) when oxygen saturation and arterial oxygen tension remained stable. The DTM was also associated with a significant but slight increase in arterial carbon dioxide tension (median, 36 mmHg vs 37 mmHg, p=0.006), and respiratory rate (median, 26 vs 30 breaths/min, p=0.05). Other parameters were unaltered. The DTM was generally judged less comfortable than the baseline oxygen delivery system, especially in patients requiring low oxygen flow at baseline. Conclusions: The DTM is a simple and efficient system to reduce oxygen consumption. This may have clinical implications in places where oxygen supplies are limited.