Treatment with noninvasive oxygenation strategies such as noninvasive ventilation and high-flow nasal oxygen may be more effective than standard oxygen therapy alone in patients with acute hypoxemic ...respiratory failure.
To compare the association of noninvasive oxygenation strategies with mortality and endotracheal intubation in adults with acute hypoxemic respiratory failure.
The following bibliographic databases were searched from inception until April 2020: MEDLINE, Embase, PubMed, Cochrane Central Register of Controlled Trials, CINAHL, Web of Science, and LILACS. No limits were applied to language, publication year, sex, or race.
Randomized clinical trials enrolling adult participants with acute hypoxemic respiratory failure comparing high-flow nasal oxygen, face mask noninvasive ventilation, helmet noninvasive ventilation, or standard oxygen therapy.
Two reviewers independently extracted individual study data and evaluated studies for risk of bias using the Cochrane Risk of Bias tool. Network meta-analyses using a bayesian framework to derive risk ratios (RRs) and risk differences along with 95% credible intervals (CrIs) were conducted. GRADE methodology was used to rate the certainty in findings.
The primary outcome was all-cause mortality up to 90 days. A secondary outcome was endotracheal intubation up to 30 days.
Twenty-five randomized clinical trials (3804 participants) were included. Compared with standard oxygen, treatment with helmet noninvasive ventilation (RR, 0.40 95% CrI, 0.24-0.63; absolute risk difference, -0.19 95% CrI, -0.37 to -0.09; low certainty) and face mask noninvasive ventilation (RR, 0.83 95% CrI, 0.68-0.99; absolute risk difference, -0.06 95% CrI, -0.15 to -0.01; moderate certainty) were associated with a lower risk of mortality (21 studies 3370 patients). Helmet noninvasive ventilation (RR, 0.26 95% CrI, 0.14-0.46; absolute risk difference, -0.32 95% CrI, -0.60 to -0.16; low certainty), face mask noninvasive ventilation (RR, 0.76 95% CrI, 0.62-0.90; absolute risk difference, -0.12 95% CrI, -0.25 to -0.05; moderate certainty) and high-flow nasal oxygen (RR, 0.76 95% CrI, 0.55-0.99; absolute risk difference, -0.11 95% CrI, -0.27 to -0.01; moderate certainty) were associated with lower risk of endotracheal intubation (25 studies 3804 patients). The risk of bias due to lack of blinding for intubation was deemed high.
In this network meta-analysis of trials of adult patients with acute hypoxemic respiratory failure, treatment with noninvasive oxygenation strategies compared with standard oxygen therapy was associated with lower risk of death. Further research is needed to better understand the relative benefits of each strategy.
Drs. Joffe and Galgon suggest that the use of a pneumotachograph (PNT) would increase the study validity and power (by decreasing random error), with reference to PNT as the gold standard for ...accurately measuring pressures and flows versus the use of the anesthesia machine's sensors. ...the concern regarding our oropharyngeal airway use is also mitigated by crossover design.
Purpose
Over the last two decades, noninvasive ventilation (NIV) has been proposed in various causes of acute respiratory failure (ARF) but some indications are debated. Current trends in NIV use are ...unknown.
Methods
Comparison of three multicenter prospective audits including all patients receiving mechanical ventilation and conducted in 1997, 2002, and 2011 in francophone countries.
Results
Among the 4132 patients enrolled, 2094 (51 %) required ventilatory support for ARF and 2038 (49 %) for non-respiratory conditions. Overall NIV use was markedly increased in 2010/11 compared to 1997 and 2002 (37 % of mechanically ventilated patients vs. 16 % and 28 %,
P
< 0.05). In 2010/11, the use of first-line NIV for ARF had reached a plateau (24 % vs. 16 % and 23 %,
P
< 0.05) whereas pre-ICU and post-extubation NIV had substantially increased (11 % vs. 4 % and 11 % vs. 7 %, respectively,
P
< 0.05). First-line NIV remained stable in acute-on-chronic RF, continued to increase in cardiogenic pulmonary edema, but decreased in de novo ARF (16 % in 2010/11 vs. 23 % in 2002,
P
< 0.05). The NIV success rate increased from 56 % in 2002 to 70 % in 2010/11 and remained the lowest in de novo ARF. NIV failure in de novo ARF was associated with increased mortality in 2002 but not in 2010/11. Mortality decreased over time, and overall, NIV use was associated with a lower mortality.
Conclusion
Increases in NIV use and success rate, an overall decrease in mortality, and a decrease of the adverse impact NIV failure has in de novo ARF suggest better patient selection and greater proficiency of staff in administering NIV.
Trial registration
Clinicaltrials.gov Identifier NCT01449331.
Corner rooms with two or more open windows in perpendicular facades can be naturally ventilated in cross-ventilation or pumping ventilation. These two airflow regimes also occur in rooms with two ...openings in the same façade, in the form of single sided pumping or cross sided ventilation. This paper presents an experimental and numerical simulation study of the scale and occurrence of these two flow regimes for rooms in a rectangular building exposed to wind. Flow visualization and tracer gas measurement of effective airflow were performed in an atmospheric boundary layer wind tunnel using a rectangular model of a three-story building (1/20 scale) with a ventilated middle floor. Experimental results show that pumping ventilation occurs when the wind is perpendicular to the façade (single sided rooms) or aligned with the building corner (corner rooms). In addition to these two perfectly aligned wind directions, pumping also occurs for a range of incoming wind angles: ±19° for single sided; and ±9° for corner rooms. As a result, for isolated rectangular buildings that have, at least, one single sided and two corner rooms in each facade, pumping ventilation can potentially occur in two or more rooms for 62 % of incoming wind directions. To investigate the transition between steady cross-ventilation and unsteady pumping ventilation, three-dimensional computational fluid dynamics large eddy simulations were performed to obtain wind generated pressures in the ventilation openings. Results show that the transition from cross-ventilation to pumping occurs when the steady pressure becomes smaller than the unsteady component. These results are used to develop a pressure based simplified model for corner ventilation that can predict effective airflow from external wind generated pressures with an average error below 10.2 %.
•Pumping ventilation of front and back corner rooms was identified.•An isolated building with multiple single sided and corner rooms can have pumping in 62 % of the incoming wind directions.•Pumping mechanism occurs whenever the steady pressure difference at the openings becomes smaller than the unsteady component.•A simplified model for corner ventilation was proposed.
Background and purpose
Forced vital capacity (FVC) <80% is one of the key indications for starting non‐invasive ventilation (NIV) in amyotrophic lateral sclerosis (ALS). It was hypothesized that a ...very early start of NIV could lengthen the free interval before death compared to later‐start NIV; as a secondary outcome, the survival rate of patients on NIV without tracheotomy was also evaluated.
Methods
This retrospective study was conducted on 194 ALS patients, divided into a later group (LG) with FVC <80% at NIV prescription (n = 129) and a very early group (VEG) with FVC ≥80% at NIV prescription (n = 65). Clinical and respiratory functional data and time free to death between groups over a 3‐year follow‐up were compared.
Result
At 36 months from diagnosis, mortality was 35% for the VEG versus 52.7% for the LG (P = 0.022). Kaplan−Meier survival curves adjusted for tracheotomy showed a lower probability of death (P = 0.001) for the VEG as a whole (P = 0.001) and for the non‐bulbar (NB) subgroup (P = 0.007). Very early NIV was protective of survival for all patients hazard ratio (HR) 0.45; 95% confidence interval (CI) 0.28–0.74; P = 0.001 and for the NB subgroup (HR 0.43; 95% CI 0.23–0.79; P = 0.007), whilst a tracheotomy was protective for all patients (HR 0.27; 95% CI 0.15–0.50; P = 0.000) and both NB (HR 0.26; 95% CI 0.12–0.56; P = 0.001) and bulbar subgroups (HR 0.29; 95% CI 0.11–0.77; P = 0.013). Survival in VEG patients on NIV without tracheotomy was three times that for the LG (43.1% vs. 14.7%).
Conclusion
Very early NIV prescription prolongs the free time from diagnosis to death in NB ALS patients whilst tracheotomy reduces the mortality risk in all patients.
High-flow conditioned oxygen therapy delivered through nasal cannulae and noninvasive mechanical ventilation (NIV) may reduce the need for reintubation. Among the advantages of high-flow oxygen ...therapy are comfort, availability, lower costs, and additional physiopathological mechanisms.
To test if high-flow conditioned oxygen therapy is noninferior to NIV for preventing postextubation respiratory failure and reintubation in patients at high risk of reintubation.
Multicenter randomized clinical trial in 3 intensive care units in Spain (September 2012-October 2014) including critically ill patients ready for planned extubation with at least 1 of the following high-risk factors for reintubation: older than 65 years; Acute Physiology and Chronic Health Evaluation II score higher than 12 points on extubation day; body mass index higher than 30; inadequate secretions management; difficult or prolonged weaning; more than 1 comorbidity; heart failure as primary indication for mechanical ventilation; moderate to severe chronic obstructive pulmonary disease; airway patency problems; or prolonged mechanical ventilation.
Patients were randomized to undergo either high-flow conditioned oxygen therapy or NIV for 24 hours after extubation.
Primary outcomes were reintubation and postextubation respiratory failure within 72 hours. Noninferiority margin was 10 percentage points. Secondary outcomes included respiratory infection, sepsis, and multiple organ failure, length of stay and mortality; adverse events; and time to reintubation.
Of 604 patients (mean age, 65 SD, 16 years; 388 64% men), 314 received NIV and 290 high-flow oxygen. Sixty-six patients (22.8%) in the high-flow group vs 60 (19.1%) in the NIV group were reintubation (absolute difference, -3.7%; 95% CI, -9.1% to ∞); 78 patients (26.9%) in the high-flow group vs 125 (39.8%) in the NIV group experienced postextubation respiratory failure (risk difference, 12.9%; 95% CI, 6.6% to ∞) corrected. Median time to reintubation did not significantly differ: 26.5 hours (IQR, 14-39 hours) in the high-flow group vs 21.5 hours (IQR, 10-47 hours) in the NIV group (absolute difference, -5 hours; 95% CI, -34 to 24 hours). Median postrandomization ICU length of stay was lower in the high-flow group, 3 days (IQR, 2-7) vs 4 days (IQR, 2-9; P=.048). Other secondary outcomes were similar in the 2 groups. Adverse effects requiring withdrawal of the therapy were observed in none of patients in the high-flow group vs 42.9% patients in the NIV group (P < .001).
Among high-risk adults who have undergone extubation, high-flow conditioned oxygen therapy was not inferior to NIV for preventing reintubation and postextubation respiratory failure. High-flow conditioned oxygen therapy may offer advantages for these patients.
clinicaltrials.gov Identifier: NCT01191489.
High-flow nasal oxygen therapy is increasingly used for acute hypoxemic respiratory failure (AHRF).
To determine whether high-flow oxygen therapy decreases mortality among immunocompromised patients ...with AHRF compared with standard oxygen therapy.
The HIGH randomized clinical trial enrolled 776 adult immunocompromised patients with AHRF (Pao2 <60 mm Hg or Spo2 <90% on room air, or tachypnea >30/min or labored breathing or respiratory distress, and need for oxygen ≥6 L/min) at 32 intensive care units (ICUs) in France between May 19, 2016, and December 31, 2017.
Patients were randomized 1:1 to continuous high-flow oxygen therapy (n = 388) or to standard oxygen therapy (n = 388).
The primary outcome was day-28 mortality. Secondary outcomes included intubation and mechanical ventilation by day 28, Pao2:Fio2 ratio over the 3 days after intubation, respiratory rate, ICU and hospital lengths of stay, ICU-acquired infections, and patient comfort and dyspnea.
Of 778 randomized patients (median age, 64 IQR, 54-71 years; 259 33.3% women), 776 (99.7%) completed the trial. At randomization, median respiratory rate was 33/min (IQR, 28-39) vs 32 (IQR, 27-38) and Pao2:Fio2 was 136 (IQR, 96-187) vs 128 (IQR, 92-164) in the intervention and control groups, respectively. Median SOFA score was 6 (IQR, 4-8) in both groups. Mortality on day 28 was not significantly different between groups (35.6% vs 36.1%; difference, -0.5% 95% CI, -7.3% to +6.3%; hazard ratio, 0.98 95% CI, 0.77 to 1.24; P = .94). Intubation rate was not significantly different between groups (38.7% vs 43.8%; difference, -5.1% 95% CI, -12.3% to +2.0%). Compared with controls, patients randomized to high-flow oxygen therapy had a higher Pao2:Fio2 (150 vs 119; difference, 19.5 95% CI, 4.4 to 34.6) and lower respiratory rate after 6 hours (25/min vs 26/min; difference, -1.8/min 95% CI, -3.2 to -0.2). No significant difference was observed in ICU length of stay (8 vs 6 days; difference, 0.6 95% CI, -1.0 to +2.2), ICU-acquired infections (10.0% vs 10.6%; difference, -0.6% 95% CI, -4.6 to +4.1), hospital length of stay (24 vs 27 days; difference, -2 days 95% CI, -7.3 to +3.3), or patient comfort and dyspnea scores.
Among critically ill immunocompromised patients with acute respiratory failure, high-flow oxygen therapy did not significantly decrease day-28 mortality compared with standard oxygen therapy.
clinicaltrials.gov Identifier: NCT02739451.
Ventilation systems for commercial airliner cabins are important in reducing contaminant transport and maintaining thermal comfort. To evaluate the performance of a personalized displacement ...ventilation system, a conventional displacement ventilation system, and a mixing ventilation system, this study first used the Wells‐Riley equation integrated with CFD to obtain the SARS quanta value based on a specific SARS outbreak on a flight. This investigation then compared the three ventilation systems in a seven‐row section of a fully occupied, economy‐class cabin in Boeing 737 and Boeing 767 airplanes. The SARS quanta generation rate obtained for the index patient could be used in future studies. For all the assumed source locations, the passengers’ infection risk by air in the two planes was the highest with the mixing ventilation system, while the conventional displacement ventilation system produced the lowest risk. The personalized ventilation system performed the best in maintaining cabin thermal comfort and can also reduce the infection risk. This system is recommended for airplane cabins.
Today, invasive and non-invasive home mechanical ventilation have become a well-established treatment option. Consequently, in 2010, the German Respiratory Society (DGP) has leadingly published the ...guidelines on "Non-Invasive and Invasive Mechanical Ventilation for Treatment of Chronic Respiratory Failure." However, continuing technical evolutions, new scientific insights, and health care developments require an extensive revision of the guidelines. For this reason, the updated guidelines are now published. Thereby, the existing chapters, namely technical issues, organizational structures in Germany, qualification criteria, disease-specific recommendations including special features in pediatrics as well as ethical aspects and palliative care, have been updated according to the current literature and the health care developments in Germany. New chapters added to the guidelines include the topics of home mechanical ventilation in paraplegic patients and in those with failure of prolonged weaning. In the current guidelines, different societies as well as professional and expert associations have been involved when compared to the 2010 guidelines. Importantly, disease-specific aspects are now covered by the German Interdisciplinary Society of Home Mechanical Ventilation (DIGAB). In addition, societies and associations directly involved in the care of patients receiving home mechanical ventilation have been included in the current process. Importantly, associations responsible for decisions on costs in the health care system and patient organizations have now been involved.
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