74 research outputs found
Mixing Within Patterned Vortex Core
The video shows the flow dynamics within inner and outer regions of a vortex
core. The observed phenomena mimic a transport process occurring within the
Antarctic vortex. The video shows two distinct regions: a strongly mixed core
and broad ring of weakly mixed region extending out the vortex core boundaries.
The two regions are separated by a thin layer that isolates the weakly and
strongly mixed regions; this thin layer behaves as barrier to the mixing of the
two regions. The video shows that the barriers deplete when a swirl of the
vortex core increases and the vortex core espouses a triangular pattern.Comment: 62nd Annual Meeting of the APS Division of Fluid Dynamics, Fluid
Dynamics Vide
Prone Vs. Supine Position Ventilation in Intubated COVID-19 Patients: A Systematic Review and Meta-Analysis
Whether prone positioning of patients undergoing mechanical ventilation for COVID-19 pneumonia has benefits over supine positioning is not clear. We conducted a systematic review with meta-analysis to determine whether prone versus supine positioning during ventilation resulted in different outcomes for patients with COVID-19 pneumonia. We searched Ovid Medline, Embase, and Web of Science for prospective and retrospective studies up through April 2023. We included studies that compared outcomes of patients with COVID-19 after ventilation in prone and supine positions. The primary outcomes were three mortality measures: hospital, overall, and intensive care unit (ICU). Secondary outcomes were mechanical ventilation days, intensive care unit (ICU) length of stay, and hospital length of stay. We conducted risk of bias analysis and used meta-analysis software to analyze results. Mean difference (MD) was used for continuous data, and odds ratio (OR) was used for dichotomous data, both with 95% CIs. Significant heterogeneity (I(2)) was considered if I(2) was \u3e50%. A statistically significant result was considered if the p-value was \u3c0.05. Of 1787 articles identified, 93 were retrieved, and seven retrospective cohort studies encompassing 5216 patients with COVID-19 were analyzed. ICU mortality was significantly higher in the prone group (OR 2.22, 95% CI 1.43-3.43; p=0.0004). No statistically significant difference was observed between prone and supine groups for hospital mortality (OR, 0.95; 95% CI, 0.66-1.37; p=0.78) or overall mortality (OR, 1.08; 95% CI, 0.72-1.64; p=0.71). Studies that analyzed primary outcomes had significant heterogeneity. Hospital length of stay was significantly higher in the prone than in the supine group (MD, 6.06; 95 % CI, 3.15-8.97; p\u3c0.0001). ICU length of stay and days of mechanical ventilation did not differ between the two groups. In conclusion, mechanical ventilation with prone positioning for all patients with COVID-19 pneumonia may not provide a mortality benefit over supine positioning
Emergent Surgical Airway Skills: Time to Re-evaluate the Competencies
Introduction: One of the most challenging scenarios an anesthesia provider can face is treating a can\u27t intubate can\u27t ventilate (CICV) patient. The incidence of CICV is estimated to be around one in 10,000 cases. According to the American Society of Anesthesiology Closed Claims Study, adverse respiratory events are the most common type of injury, with difficult intubation and ventilation contributing to the majority of these cases. The objective of this non-interventional quality improvement project was to evaluate the prior training, exposure, and self-reported confidence in handling the CICV scenario among anesthesia providers at Henry Ford Hospital in Detroit, MI.
Methods: An online questionnaire was distributed via email to all residents, certified registered nurse anesthetists (CRNAs), and attending anesthesiologists in March 2021. The email contained a link to an online questionnaire via Microsoft Forms (Microsoft Corporation, Redmond, WA). Univariate group comparisons were carried out between the respondents\u27 role (attending, CRNA, or resident), as well as between the number of years that the respondents were in practice (\u3c 5 years, 5-10 years, \u3e 10 years).
Results: Out of the total 170 anesthesia providers, 119 participated in the study where 54 (45%) were attendings, 44 (37%) were residents, and 21 (18%) were CRNAs. The majority (75%) did not know the surgical airway kit location, and 87% had not performed the surgical airway procedure before. The vast majority (96.7%) recommended simulation training compared to online training or lecture series, and just over 50% recommended annual training frequency. When looking at the differences in responses based on years of experience as an anesthesia provider, the majority of those with \u3e 10 years in practice knew how to perform the surgical airway technique while respondents with \u3c 5 years did not know how to perform the technique, and 50% of those with five to 10 years experience knew how to perform the surgical airway procedure for a CICV scenario.
Conclusion: Although there were many significant differences observed between the various provider roles and years in practice, surprisingly, the responses revealed both a lack of experience and confidence in performing the surgical airway procedure in all provider roles. These findings highlight a need for better emergency airway teaching and training. These findings will be used to guide the design and implementation of improved surgical airway training for residents, CRNAs, and attending anesthesiologists with the goal of better preparedness for handling a CICV scenario
Sequential Organ Failure Assessment (SOFA) Score and Mortality Prediction in Patients With Severe Respiratory Distress Secondary to COVID-19
Background: This study looks at the validity of the sequential organ failure assessment score (SOFA) in detecting mortality in patients with Coronavirus disease of 2019 (COVID-19) pneumonia. Also, it is looking to determine the optimal SOFA score that will discriminate between mortality and survival.
Methods: It is a retrospective chart review of the patients admitted to Henry Ford Hospital from March 2020 to December 2020 with COVID-19 pneumonia who developed severe respiratory distress. We collected the following information; patient demographics (age, sex, body mass index), co-morbidities (history of diabetes mellitus, chronic kidney disease, chronic obstructive pulmonary disease, coronary artery disease, or cancer), SOFA scores (the ratio of arterial oxygen tension (PaO(2)) to the fraction of inspired oxygen, Glasgow Coma Scale (GCS) score, mean arterial pressure, serum creatinine level, bilirubin level, and platelet count) as well as inpatient mortality.
Results: There were 320 patients; out of these, 111 were intubated. The receiver operating characteristic (ROC) curve for SOFA at the moment of inclusion in the study had an area under the curve of 0.883. The optimal point for discrimination between mortality and survival is SOFA of 5. A SOFA score of less than two is associated with 100% survival, while a score of more than 11 is associated with 100% mortality.
Conclusions: SOFA score in COVID-19 patients with severe respiratory distress strongly correlates with the initial SOFA score. It is a valuable tool for predicting mortality in COVID-19 patients
The effect of viscosity on the rotating waves and polygonal patterns within a hollow vortex core
The question of how viscosity influences the development of instabilities within a rotating shallow layer of liquid, which gives rise to polygonal patterns, has been investigated experimentally. A phase diagram of the existence regions of these polygonal patterns is constructed in plane, where Fr is the Froude number and Ta is the Taylor number. The results show that the effect of the viscosity on the domain of existence of the patterns depends on the initial fluid height above the rotating disc. The results also show that the variation of viscosity does not affect the locking ratio between the rotational frequencies of the pattern to the disc; the two frequencies remain locked at approximately 1/3
A note on relative equilibria in a rotating shallow water layer
AbstractRelative equilibria of two and three satellite vortices in a rotating shallow water layer have been recorded via particle image velocimetry (PIV) and their autorotation speed was estimated. This study shows that these equilibria retain the fundamental characteristics of Kelvin’s equilibria, and could be adequately described by the classical idealized point vortex theory. The same conclusion can also be inferred using the experimental dataset of Bergmann et al. (J. Fluid Mech., vol. 679, 2011, pp. 415–431; J. Fluid Mech., vol. 691, 2012, pp. 605–606) if the assigned field’s contribution to pattern rotation is included.</jats:p
Effect of Intubation Timing on the Outcome of Patients With Severe Respiratory Distress Secondary to COVID-19 Pneumonia.
Background: The optimal timing of intubation for critically ill patients with severe respiratory illness remains controversial among healthcare providers. The coronavirus disease 2019 (COVID-19) pandemic has raised even more questions about when to implement this life-saving therapy. While one group of providers prefers early intubation for patients with respiratory distress because these patients may deteriorate rapidly without it, other providers believe that intubation should be delayed or avoided because of its associated risks including worse outcomes.
Research question: Our objective was to assess whether the timing of intubation in patients with severe COVID-19 pneumonia was associated with differences in mortality or other outcomes.
Study design and methods: This was a single-center retrospective observational cohort study. We analyzed outcomes of patients who were intubated secondary to COVID-19 pneumonia between March 13, 2020, and December 12, 2020, at Henry Ford Hospital in Detroit, Michigan. Patients were categorized into two groups: early intubated (intubated within 24 hours of the onset of severe respiratory distress) and late intubated (intubated after 24 hours of the onset of severe respiratory distress). Demographics, comorbidities, respiratory rate oxygenation (ROX) index, sequential organ failure assessment (SOFA) score, and treatment received were compared between groups. The primary outcome was mortality. Secondary outcomes were ventilation time, intensive care unit stay, hospital length of stay, and discharge disposition. Post hoc and Kaplan-Meier survival analyses were performed.
Results: A total of 110 patients were included: 55 early intubated and 55 late intubated. We did not observe a significant difference in overall mortality between the early intubated (43%) and the late intubated groups (53%) (p = 0.34). There was no statistically significant difference in patients\u27 baseline characteristics including SOFA scores (the early intubation group had a mean score of 7.5 compared to 6.7 in the late intubation group). Based on the ROX index, the early intubation group had significantly more patients with a reduced risk of intubation (45%) than the late group (27%) (p = 0.029). The early intubation group was treated with a high-flow nasal cannula at a significantly lower rate (47%) than the late intubation group (83%) (p \u3c 0.001). Significant differences in patient baseline characteristics, treatment received, and other outcomes were not observed. Post hoc analysis adjusting for SOFA score between 0 and 9 revealed significantly higher mortality in the late intubation group (49%) than in the early intubation group (26%) (p = 0.03). Patients in the 0 to 9 SOFA group who were intubated later had 2.7 times the odds of dying during hospital admission compared to patients who were intubated early (CI, 1.09-6.67).
Interpretation: The timing of intubation for patients with severe COVID-19 pneumonia was not significantly associated with overall mortality or other patient outcomes. However, within the subgroup of patients with SOFA scores of 9 or lower at the time of intubation, patients intubated after 24 hours of the onset of respiratory distress had a higher risk of death than those who were intubated within 24 hours of respiratory distress. Thus, patients with COVID-19 pneumonia who are not at a high level of organ dysfunction may benefit from early mechanical ventilation
Symmetry-Breaking of Interfacial Polygonal Patterns and Synchronization of Travelling Waves within a Hollow-Core Vortex
- …