Whether respiratory physiology of COVID-19-induced respiratory failure is different from acute respiratory distress syndrome (ARDS) of other etiologies is unclear. We conducted a single-center study ...to describe respiratory mechanics and response to positive end-expiratory pressure (PEEP) in COVID-19 ARDS and to compare COVID-19 patients to matched-control subjects with ARDS from other causes.
Thirty consecutive COVID-19 patients admitted to an intensive care unit in Rome, Italy, and fulfilling moderate-to-severe ARDS criteria were enrolled within 24 h from endotracheal intubation. Gas exchange, respiratory mechanics, and ventilatory ratio were measured at PEEP of 15 and 5 cmH
O. A single-breath derecruitment maneuver was performed to assess recruitability. After 1:1 matching based on PaO
/FiO
, FiO
, PEEP, and tidal volume, COVID-19 patients were compared to subjects affected by ARDS of other etiologies who underwent the same procedures in a previous study.
Thirty COVID-19 patients were successfully matched with 30 ARDS from other etiologies. At low PEEP, median 25th-75th percentiles PaO
/FiO
in the two groups was 119 mmHg 101-142 and 116 mmHg 87-154. Average compliance (41 ml/cmH
O 32-52 vs. 36 ml/cmH
O 27-42, p = 0.045) and ventilatory ratio (2.1 1.7-2.3 vs. 1.6 1.4-2.1, p = 0.032) were slightly higher in COVID-19 patients. Inter-individual variability (ratio of standard deviation to mean) of compliance was 36% in COVID-19 patients and 31% in other ARDS. In COVID-19 patients, PaO
/FiO
was linearly correlated with respiratory system compliance (r = 0.52 p = 0.003). High PEEP improved PaO
/FiO
in both cohorts, but more remarkably in COVID-19 patients (p = 0.005). Recruitability was not different between cohorts (p = 0.39) and was highly inter-individually variable (72% in COVID-19 patients and 64% in ARDS from other causes). In COVID-19 patients, recruitability was independent from oxygenation and respiratory mechanics changes due to PEEP.
Early after establishment of mechanical ventilation, COVID-19 patients follow ARDS physiology, with compliance reduction related to the degree of hypoxemia, and inter-individually variable respiratory mechanics and recruitability. Physiological differences between ARDS from COVID-19 and other causes appear small.
Oxygen therapy can be delivered using low-flow, intermediate-flow (air entrainment mask), or high-flow devices. Low/intermediate-flow oxygen devices have several drawbacks that cause critically ill ...patients discomfort and translate into suboptimal clinical results. These include limitation of the FiO
2
(due to the high inspiratory flow often observed in patients with respiratory failure), and insufficient humidification and warming of the inspired gas. High-flow nasal cannula oxygenation (HFNCO) delivers oxygen flow rates of up to 60 L/min and over the last decade its effect on clinical outcomes has widely been evaluated, such as in the improvement of respiratory distress, the need for intubation, and mortality. Mechanisms of action of HFNCO are complex and not limited to the increased oxygen flow rate. The main aim of this review is to guide clinicians towards evidence-based clinical practice guidelines. It summarizes current knowledge about HFNCO use in ICU patients and the potential areas of uncertainties. For instance, it has been recently suggested that HFNCO could improve the outcome of patients with hypoxemic acute respiratory failure. In other settings, research is ongoing and additional evidence is needed. For instance, if intubation is required, studies suggest that HFNCO may help to improve preoxygenation and can be used after extubation. Likewise, HFNCO might be used in obese patients, or to prevent respiratory deterioration in hypoxemic patients requiring bronchoscopy, or for the delivery of aerosol therapy. However, areas for which conclusive data exist are limited and interventions using standardized HFNCO protocols, comparators, and relevant clinical outcomes are warranted.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Baseline characteristics and management have changed over time in patients requiring mechanical ventilation; however, the impact of these changes on patient outcomes is unclear.
To estimate whether ...mortality in mechanically ventilated patients has changed over time.
Prospective cohort studies conducted in 1998, 2004, and 2010, including patients receiving mechanical ventilation for more than 12 hours in a 1-month period, from 927 units in 40 countries. To examine effects over time on mortality in intensive care units, we performed generalized estimating equation models.
We included 18,302 patients. The reasons for initiating mechanical ventilation varied significantly among cohorts. Ventilatory management changed over time (P < 0.001), with increased use of noninvasive positive-pressure ventilation (5% in 1998 to 14% in 2010), a decrease in tidal volume (mean 8.8 ml/kg actual body weight SD = 2.1 in 1998 to 6.9 ml/kg SD = 1.9 in 2010), and an increase in applied positive end-expiratory pressure (mean 4.2 cm H2O SD = 3.8 in 1998 to 7.0 cm of H2O SD = 3.0 in 2010). Crude mortality in the intensive care unit decreased in 2010 compared with 1998 (28 versus 31%; odds ratio, 0.87; 95% confidence interval, 0.80-0.94), despite a similar complication rate. Hospital mortality decreased similarly. After adjusting for baseline and management variables, this difference remained significant (odds ratio, 0.78; 95% confidence interval, 0.67-0.92).
Patient characteristics and ventilation practices have changed over time, and outcomes of mechanically ventilated patients have improved. Clinical trials registered with www.clinicaltrials.gov (NCT01093482).
The feasibility problem is studied of achieving a specified formation among a group of autonomous unicycles by local distributed control. The directed graph defined by the information flow plays a ...key role. It is proved that formation stabilization to a point is feasible if and only if the sensor digraph has a globally reachable node. A similar result is given for formation stabilization to a line and to more general geometric arrangements.
...as Macklin effect precedes overt PMD development by several days, we can now hypothesize that early identification of Macklin effect could be used to identify patients at risk for or with ongoing ...P-SILI and select patients for different treatment algorithms. Furthermore, these findings reinforce the concept that excessive transpulmonary pressure such as those developed during inspiration supported by PSV in patients with respiratory distress may exacerbate P-SILI and may indeed induce barotrauma through the Macklin effect. ...the choice of adequate noninvasive ventilatory support could become fundamental to mitigate Macklin's progression. ...considering the aforementioned limitation, we suggest using advanced respiratory monitoring (electrical activity of the diaphragm, lung ultrasound, electrical impedance tomography, esophageal pressure 4) to assess the risk of P-SILI early.
Abstract
Background
The effects of awake prone position on the breathing pattern of hypoxemic patients need to be better understood. We conducted a crossover trial to assess the physiological effects ...of awake prone position in patients with acute hypoxemic respiratory failure.
Methods
Fifteen patients with acute hypoxemic respiratory failure and PaO
2
/FiO
2
< 200 mmHg underwent high-flow nasal oxygen for 1 h in supine position and 2 h in prone position, followed by a final 1-h supine phase. At the end of each study phase, the following parameters were measured: arterial blood gases, inspiratory effort (Δ
P
ES
), transpulmonary driving pressure (Δ
P
L
), respiratory rate and esophageal pressure simplified pressure–time product per minute (sPTP
ES
) by esophageal manometry, tidal volume (
V
T
), end-expiratory lung impedance (EELI), lung compliance, airway resistance, time constant, dynamic strain (
V
T
/EELI) and pendelluft extent through electrical impedance tomography.
Results
Compared to supine position, prone position increased PaO
2
/FiO
2
(median Interquartile range 104 mmHg 76–129 vs. 74 69–93,
p
< 0.001), reduced respiratory rate (24 breaths/min 22–26 vs. 27 26–30,
p
= 0.05) and increased Δ
P
ES
(12 cmH
2
O 11–13 vs. 9 8–12,
p
= 0.04) with similar sPTP
ES
(131 75–154 cmH
2
O s min
−1
vs. 105 81–129,
p
> 0.99) and Δ
P
L
(9 7–11 cmH
2
O vs. 8 5–9,
p
= 0.17). Airway resistance and time constant were higher in prone vs. supine position (9 cmH
2
O s arbitrary units
−3
4–11 vs. 6 4–9,
p
= 0.05; 0.53 s 0.32–61 vs. 0.40 0.37–0.44,
p
= 0.03). Prone position increased EELI (3887 arbitrary units 3414–8547 vs. 1456 959–2420,
p
= 0.002) and promoted
V
T
distribution towards dorsal lung regions without affecting
V
T
size and lung compliance: this generated lower dynamic strain (0.21 0.16–0.24 vs. 0.38 0.30–0.49,
p
= 0.004). The magnitude of pendelluft phenomenon was not different between study phases (55% 7–57 of
V
T
in prone vs. 31% 14–55 in supine position,
p
> 0.99).
Conclusions
Prone position improves oxygenation, increases EELI and promotes
V
T
distribution towards dependent lung regions without affecting
V
T
size, Δ
P
L
, lung compliance and pendelluft magnitude. Prone position reduces respiratory rate and increases Δ
P
ES
because of positional increases in airway resistance and prolonged expiratory time. Because high Δ
P
ES
is the main mechanistic determinant of self-inflicted lung injury, caution may be needed in using awake prone position in patients exhibiting intense Δ
P
ES
.
Clinical trail registeration
: The study was registered on clinicaltrials.gov (NCT03095300) on March 29, 2017.
Abstract The cooling of secondary beams is important for accelerator-based nuclear physics. In the radiofrequency (RF) quadrupole cooler (RFQC), RF fields and ion-gas collisions may give a ...considerable increase or decrease of the beam transverse emittance and energy spread, depending on a delicate tuning of heating and cooling effects, dominated by the ion beam kinetic energy and the balance of collisions and confinement forces. An extra confinement may be added by a solenoid magnetic field, as in the RFQC prototype installed in the Eltrap machine. This provides a versatile test bench (distinct from a closed accelerator installation) for detailed studies of cooling dynamics and of several RFQC technical optimizations (for gas differential pumping and bias voltages). Modeling concepts and simulation results are summarized. The major RFQC parameters are reviewed, in particular for 133 Cs + collisions against He gas whose pressure p g ranges from 2 to 9 Pa in the reference case, with attention to the extraction, comparing triode/tetrode system, and to the bias voltages. Lower bias voltages request less p g , but provide less cooling of the energy spread.
Background
Learning assistants (LAs) increase accessibility to instructor–student interactions in large STEM lecture classes. In this research, we used the Formative Assessment Enactment Model ...developed for K-12 science teachers to characterize LA facilitation practices. The Formative Assessment Enactment Model describes instructor actions as eliciting or advancing student thinking, guided by their purposes and the perspective they center as well as by what they notice about and how they interpret student thinking. Thus, it describes facilitation practices in a holistic way, capturing the way purposes, perspectives, noticing, interpreting, and actions are intertwined and working together to characterize different LA actions. In terms of how perspectives influence actions, eliciting and advancing moves can be enacted either in authoritative ways, driven by one perspective that has authority, or in dialogic ways, driven by multiple perspectives. Dialogic practices are of particular interest because of their potential to empower students and center student thinking.
Results
Our analysis of video recordings of LA–student interactions and stimulated recall interviews with 37 introductory physical science lectures’ LAs demonstrates that instead of as a dichotomy between authoritative and dialogic, LA actions exist along a spectrum of authoritative to dialogic based on the perspectives centered. Between the very authoritative perspective that centers on canonically correct science and the very dialogic perspective that centers the perspectives of the students involved in the discussion, we find two intermediary categories. The two new categories encompass a moderately authoritative perspective focused on the LA’s perspective without the claim of being correct and a moderately dialogic perspective focused on ideas from outside the current train of thought such as from students in the class that are not part of the current discussion.
Conclusions
This spectrum further adds to theory around authoritative and dialogic practices as it reconsiders what perspectives can drive LA enactment of facilitation other than the perspective of canonically correct science and the perspectives of the students involved in the discussion. This emerging characterization may be used to give LAs and possibly other instructors a tool to intentionally shift between authoritative and dialogic practices. It may also be used to transition towards more student-centered practices.
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Echinococcus granulosus causes hydatidosis or cystic echinococcosis in humans and livestock. In humans, this disease can be managed with surgery, percutaneous treatment, chemotherapy ...and/or observation. The chemotherapeutic agents used and approved for treatment of hydatidosis are benzimidazoles. Because of the difficulties in achieving successful treatment, considerable efforts have been made to find new natural compounds against hydatid disease. Beta-myrcene is a monoterpene presented in the essential oils of different plants. It is the principal component of essential oil of Rosmarinus officinalis (rosemary). The goal of the present study was to evaluate the in vitro effects of beta-myrcene against germinal cells, protoscoleces and murine cyst of E. granulosus, as well also, investigate its chemoprophylactic activity in a murine model of cystic echinococcosis. For the in vitro assays, the parasites were incubated with beta-myrcene at 10, 5 and 1 μg/mL. The treatments were dose and time-dependent, and consistent with the observed morphological alterations. In the chemoprophylactic efficacy study, the effect of beta-myrcene was similar to albendazole, the reference drug for human echinococcosis treatment.
Full text
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Both reduction in tidal volume (VT) and alveolar recruitment may be important to limit ventilator-associated lung injury during mechanical ventilation of patients with the acute respiratory distress ...syndrome (ARDS). The aim of this study was to assess the risk of alveolar derecruitment associated with VT reduction from 10 to 6 ml/kg. Whether this VT-related derecruitment could be reversed, either by a recruitment maneuver or by an increase in positive end-expiratory pressure (PEEP) level, was also investigated. Fifteen patients with ARDS were successively ventilated using conventional VT (CVT = 10 +/- 1 ml/kg) and low VT (LVT = 6 +/- 1 ml/ kg); total PEEP (PEEPtot) was individually set at the lower inflection point (Plip) of the pressure-volume curve (PEEPtot = 11 +/- 4 cm H(2)O). Pressure-volume curves were recorded from zero PEEP (ZEEP) and from PEEP, and recruited volume (Vrec) was calculated as the volume difference between the two curves for a given pressure. Despite a similar PEEPtot, Vrec was significantly lower with LVT than with CVT, indicating low VT-induced alveolar derecruitment. Reduction in VT was associated with a reduced Sa(O(2)). In 10 patients, Vrec was also measured before and after a recruitment maneuver (two sustained inflations at 45 cm H(2)O), and after an increase in PEEP (by 4 cm H(2)O). Low VT-induced derecruitment was reversed by a recruitment maneuver and by increasing PEEP. We conclude that a reduction in VT could be responsible for alveolar derecruitment, which may be transiently reversed by a reexpansion maneuver or prevented by a PEEP increase above Plip.
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