Human-to-human severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission has been established, with >3300 clinicians reported to be infected in China and >1116 clinicians infected in ...Italy, where 13 882 cases were confirmed by 13 March 2020. Room surfaces in the vicinity of coronavirus disease 2019 (COVID-19) symptomatic patients and clinicians' protective equipment were found to be contaminated 1. The primary strategy for COVID-19 patients is supportive care, including oxygen therapy for hypoxaemic patients, in which high-flow nasal cannula (HFNC) has been reported to be effective in improving oxygenation. Among patients with acute hypoxaemic respiratory failure, HFNC was proven to avoid intubation compared to conventional oxygen devices 2, 3.
Bio-aerosol dispersion
via
high-flow nasal cannula shows a similar risk to standard oxygen masks. High-flow nasal prongs with a surgical mask on the patient's face might benefit hypoxaemic COVID-19 patients without added risk for the environment.
https://bit.ly/34p7Fyy
Here, the authors examine the effect of high-flow aerosol-dispersing versus aerosol-generating procedures. Hypoxemia is the main symptom and primary reason for hospital admission among patients with ...coronavirus disease (COVID-19), and oxygen therapy is the mainstay therapy to treat hypoxemia. Among 10,054 patients with COVID-19 admitted to ICUs in the United Kingdom during the pandemic, more than 70% required advanced respiratory support, including high-flow nasal cannula (HFNC) oxygen therapy, noninvasive (NIV) and invasive ventilation, and extracorporeal membrane oxygenation. HFNC and NIV have been categorized as aerosol-generating procedures, based on the hypothesis that high-velocity gas flows may promote aerosolization of patients' secretions containing viable virus, which may then be dispersed in the environment and be inhaled by healthcare workers. Indeed, retrospective studies assessing risk factors of nosocomial transmission of the severe acute respiratory syndrome (SARS) observed that healthcare workers caring for patients with SARS treated by NIV had a twofold higher risk of infection transmission than those who did not. Furthermore, Gaeckle and colleagues provide evidence that the difference of the aerosol particle concentrations generated by various oxygenation devices is clinically insignificant and probably negligible, compared with the intersubject variability of patient-generated bioaerosols.
Abstract
As we were taught, for decades, that iodinated contrast-induced acute kidney injury should be dreaded, considerable efforts were made to find out effective measures in mitigating the renal ...risk of iodinated contrast media. Imaging procedures were frequently either downgraded (unenhanced imaging) or deferred as clinicians felt that the renal risk pertaining to contrast administration outweighed the benefits of an enhanced imaging. However, could we have missed the point? Among the abundant literature about iodinated contrast-associated acute kidney injury, recent meaningful advances may help sort out facts from false beliefs. Hence, there is increasing evidence that the nephrotoxicity directly attributable to modern iodinated CM has been exaggerated. Failure to demonstrate a clear benefit from most of the tested prophylactic measures might be an indirect consequence. However, the toxic potential of iodinated contrast media is well established experimentally and should not be overlooked completely when making clinical decisions. We herein review these advances in disease and pathophysiologic understanding and the associated clinical crossroads through a typical case vignette in the critical care setting.
We appreciate the comments of J. Elshof and co-workers on our article “High-flow nasal cannula for COVID-19 patients: low risk of bio-aerosol dispersion” 1 and agree that further research is ...warranted to reduce the risk of virus transmission from infected patients. The presented
in vitro
data of J. Elshof and co-workers from a model using light detection of smoke dispersion distance and velocity, suggesting that high-flow nasal cannula (HFNC) generates a larger dispersion distance than non-rebreather masks and Venturi masks, is in contrast to reports from H
ui
et al.
2 using a similar model. Presumably, because the smoke used by J. Elshof and co-workers was larger (0.3–2.5 µm) than that used by H
ui
et al.
2 (≤1 µm), the larger particles dispersed differently. It should be noted that smoke in both models represents only a small fraction of the range of bio-aerosols generated by patients during breathing, speaking, coughing or sneezing 3. Using the same size airway model, J. Elshof and co-workers observed that the dispersion distance decreased from 71 cm to 25 cm by changing the nasal cannula size from small to large when HFNC flow was set at 30 L·min
−1
; however, when HFNC flow was set at 60 L·min
−1
, the medium-size nasal cannula generated a shorter distance than both small and large nasal cannulas. This raises the role of proper fit of prongs to nares and highlights the limitations of modelling. Regardless of the sizes of nasal cannula, the dispersion distance was farther with 60 L·min
−1
than 30 L·min
−1
, which is in line with the results of H
ui
et al.
2 and may be expected, as higher velocity of the gas will carry exhaled smoke to a further distance. However, this effect of total flow did not occur when testing the Venturi mask. Surprisingly, the Venturi mask with large open holes and a total gas flow of 40 L·min
−1
generated a shorter dispersion distance than normal breathing. These inconsistencies are difficult to interpret without comprehensive peer review of extensive methods and results. Whether smoke imaging models truly reflect the natural features of the transportation and dispersion of bio-aerosols generated by patients has not been established and results from these studies should be interpreted cautiously.
High-flow nasal cannula does not generate higher risk of bio-aerosol dispersion than conventional oxygen masks
https://bit.ly/2Yn0RQn
Purpose
Preoxygenation with high-flow therapy by nasal cannulae (HFNC) is now widespread in the intensive care unit (ICU). However, no large randomized study has assessed its relevance in ...non-severely hypoxemic patients. In a randomized controlled trial (PROTRACH study), we aimed to evaluate preoxygenation with HFNC vs. standard bag-valve mask oxygenation (SMO) in non-severely hypoxemic patients during rapid sequence intubation (RSI) in the ICU.
Methods
Randomized controlled trial including non-severely hypoxemic patients requiring intubation in the ICU. Patients received preoxygenation by HFNC or SMO during RSI. HFNC was maintained throughout the intubation procedure whereas SMO was removed to perform laryngoscopy. The primary outcome was the lowest pulse oximetry (SpO
2
) throughout the intubation procedure. Secondary outcomes included drop in SpO
2
, adverse events related to intubation, and outcome in the ICU.
Results
A total of 192 patients were randomized. In the intent-to-treat analysis, 184 patients (HFNC
n
= 95; SMO
n
= 89), the median IQR lowest SpO
2
was 100% 97; 100 for HFNC and 99% 95; 100 for the SMO group (
P
= 0.30). Mild desaturation below 95% was more frequent with SMO (23%) than with HFNC (12%) (RR 0.51, 95% CI 0.26–0.99,
P
= 0.045). There were fewer adverse events in the HFNC group (6%) than in the SMO group (19%) (RR 0.31, 95% CI 0.13–0.76,
P
= 0.007), including fewer severe adverse events, respectively 6 (6%) and 14 (16%) with HFNC and SMO (RR 0.38, 95% CI 0.15–0.95,
P
= 0.03).
Conclusions
Compared with SMO, preoxygenation with HFNC in the ICU did not improve the lowest SpO
2
during intubation in the non-severely hypoxemic patients but led to a reduction in intubation-related adverse events.
Trial registration
Clinical trial Submission: 7 March 2016. Registry name: Benefits of high-flow nasal cannulae oxygen for preoxygenation during intubation in non-severely hypoxemic patients: the PROTRACH study. Clinicaltrials.gov identifier: NCT02700321. Eudra CT: 2015-A00145-44. CPP: 15/13-975 (Comité de protection des personnes de Rennes). URL registry:
https://clinicaltrials.gov/ct2/show/record/NCT02700321
.
National and international guidelines recommend droplet/airborne transmission and contact precautions for those caring for coronavirus disease 2019 (COVID-19) patients in ambulatory and acute care ...settings. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, an acute respiratory infectious agent, is primarily transmitted between people through respiratory droplets and contact routes. A recognized key to transmission of COVID-19, and droplet infections generally, is the dispersion of bioaerosols from the patient. Increased risk of transmission has been associated with aerosol generating procedures that include endotracheal intubation, bronchoscopy, open suctioning, administration of nebulized treatment, manual ventilation before intubation, turning the patient to the prone position, disconnecting the patient from the ventilator, noninvasive positive-pressure ventilation, tracheostomy, and cardiopulmonary resuscitation. The knowledge that COVID-19 subjects can be asymptomatic and still shed virus, producing infectious droplets during breathing, suggests that health care workers (HCWs) should assume every patient is potentially infectious during this pandemic. Taking actions to reduce risk of transmission to HCWs is, therefore, a vital consideration for safe delivery of all medical aerosols. Guidelines for use of personal protective equipment (glove, gowns, masks, shield, and/or powered air purifying respiratory) during high-risk procedures are essential and should be considered for use with lower risk procedures such as administration of uncontaminated medical aerosols. Bioaerosols generated by infected patients are a major source of transmission for SARS CoV-2, and other infectious agents. In contrast, therapeutic aerosols do not add to the risk of disease transmission unless contaminated by patients or HCWs.
Nebulized antibiotic therapy directly targets airways and lung parenchyma resulting in high local concentrations and potentially lower systemic toxicities. Experimental and clinical studies have ...provided evidence for elevated lung concentrations and rapid bacterial killing following the administration of nebulized antibiotics during mechanical ventilation. Delivery of high concentrations of antibiotics to infected lung regions is the key to achieving efficient nebulized antibiotic therapy. However, current non-standardized clinical practice, the difficulties with implementing optimal nebulization techniques and the lack of robust clinical data have limited its widespread adoption. The present review summarizes the techniques and clinical constraints for optimal delivery of nebulized antibiotics to lung parenchyma during invasive mechanical ventilation. Pulmonary pharmacokinetics and pharmacodynamics of nebulized antibiotic therapy to treat ventilator-associated pneumonia are discussed and put into perspective. Experimental and clinical pharmacokinetics and pharmacodynamics support the use of nebulized antibiotics. However, its clinical benefits compared to intravenous therapy remain to be proved. Future investigations should focus on continuous improvement of nebulization practices and techniques. Before expanding its clinical use, careful design of large phase III randomized trials implementing adequate therapeutic strategies in targeted populations is required to demonstrate the clinical effectiveness of nebulized antibiotics in terms of patient outcomes and reduction in the emergence of antibiotic resistance.
Awake prone positioning (APP) improves oxygenation in coronavirus disease (COVID-19) patients and, when successful, may decrease the risk of intubation. However, factors associated with APP success ...remain unknown. In this secondary analysis, we aimed to assess whether APP can reduce intubation rate in patients with COVID-19 and to focus on the factors associated with success.
In this multicenter randomized controlled trial, conducted in three high-acuity units, we randomly assigned patients with COVID-19-induced acute hypoxemic respiratory failure (AHRF) requiring high-flow nasal cannula (HFNC) oxygen to APP or standard care. Primary outcome was intubation rate at 28 days. Multivariate analyses were performed to identify the predictors associated to treatment success (survival without intubation).
Among 430 patients randomized, 216 were assigned to APP and 214 to standard care. The APP group had a lower intubation rate (30% vs 43%, relative risk RR 0.70; CI
0.54-0.90, P = 0.006) and shorter hospital length of stay (11 interquartile range IQR, 9-14 vs 13 IQR, 10-17 days, P = 0.001). A respiratory rate ≤ 25 bpm at enrollment, an increase in ROX index > 1.25 after first APP session, APP duration > 8 h/day, and a decrease in lung ultrasound score ≥ 2 within the first 3 days were significantly associated with treatment success for APP.
In patients with COVID-19-induced AHRF treated by HFNC, APP reduced intubation rate and improved treatment success. A longer APP duration is associated with APP success, while the increase in ROX index and decrease in lung ultrasound score after APP can also help identify patients most likely to benefit.
This study was retrospectively registered in ClinicalTrials.gov at July 20, 2021. Identification number NCT04477655. https://clinicaltrials.gov/ct2/show/NCT04477655?term=PRO-CARF&draw=2&rank=1.
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