High Mechanical Power Research Articles

The contractile efficiency of the mantle muscle of European common cuttlefish (Sepia officinalis) during cyclical contractions

Escape jet propulsion swimming in cuttlefish (Sepia officinalis) is powered by the circular muscles surrounding the mantle cavity. This mode of locomotion is energetically costly compared to undulatory swimmers. The energetic cost of swimming is determined by the mechanical power requirements and the efficiency with which chemical energy is transferred into useful mechanical work. One step in this energy transduction process is the transfer of energy from ATP hydrolysis into mechanical work by the muscles. Here, we determined the efficiency of this step, termed the contractile efficiency. Muscle preparations from the circular muscles of the mantle cavity were subjected to sinusoidal length changes at different cycle frequencies, and stimulated with a phase and duration that maximised initial net work. Changes in ATP, arginine phosphate and octopine content between control and exercised muscles were determined and used to calculate the energy released from ATP hydrolysis (Emet). The maximum contractile efficiency (the ratio of net work to Emet) was 0.37, occurring at the same cycle frequency at which mechanical power was maximal and that was used during jet propulsion swimming, suggesting that cuttlefish muscle is adapted to generate muscular power efficiently. The overall efficiency of cuttlefish jet propulsion swimming was estimated to be 0.17, which is broadly comparable to that measured during animal flight and human-powered pedalled locomotion, indicating the high energetic costs of jet propulsion swimming are not due to inefficient locomotion per se, instead, they result from the relatively high mechanical power requirements.

Lower Late Development Rate of Acute Respiratory Distress Syndrome in Patients with Lower Mechanical Power or Driving Pressure.

For patients on ventilation without acute respiratory distress syndrome (ARDS), there are, as yet, limited data on ventilation strategies. We hypothesized that driving pressure (DP) and mechanical power (MP) may play key roles for the late development of ARDS in patients without initial ARDS. A post hoc analysis of a database from our previous cohort was performed. The mean DP/MP was computed from the data before ARDS development or until ventilator support was discontinued within 28 days. The association between DP/MP and late development of ARDS within 28 days was determined. One hundred and twelve patients were enrolled, among whom seven developed ARDS. Univariate Cox regression showed that congestive heart failure (CHF) history and higher levels of mean MP and DP were associated with ARDS development. Multivariate models revealed that the mean MP and mean DP were still factors independently associated with ARDS development at hazard ratios of 1.177 and 1.226 after adjusting for the CHF effect. Areas under the receiver operating characteristic curves for mean DP/MP in predicting ARDS development were 0.813 and 0.759, respectively. In conclusion, high mean DP and MP values may be key factors associated with late ARDS development. The mean DP had a better predicted value for the development of ARDS than the mean MP.

Visualization method of mechanical power exposure intensity and duration in mechanical ventilation patients

To visualize the relationship between different combinations of mechanical power exposure intensity-duration and death risk in mechanical ventilation patients using a visualization method. Critically ill patients receiving mechanical ventilation were selected from the Medical Information Mart for Intensive Care- IV v1.0 (MIMIC- IV v1.0) database. The patients were divided into four subgroups according to oxygenation index (PaO2/FiO2) including > 300 mmHg (1 mmHg ≈ 0.133 kPa) group, 201-300 mmHg group, 101-200 mmHg group and ≤100 mmHg group. The baseline characteristics, ventilator parameters, and prognostic indicators for different patient populations were collected. For each patient, the mechanical power thresholds from low to high (5-30 J/min, increasing at intervals of 1 J/min) were used to evaluate the different exposures of mechanical power (above the set threshold was recorded as one exposure), and the number of events with different exposure intensity-duration combinations was counted based on their corresponding durations. Based on the 28-day survival/non-survival status, the number of exposures for survivors and non-survivors in each exposure intensity-duration combination was calculated, and the survival odds ratio (OR) for different mechanical power exposure intensity-duration combinations was subsequently computed. Two-dimensional tables were generated with mechanical power exposure duration on the x-axis and exposure intensity on the y-axis, and the heatmap and its corresponding equipotential line view were used to visualize the OR value to assess the risk of death. A total of 5 378 patients receiving mechanical ventilation were enrolled in the study, of whom 2 069 patients in the PaO2/FiO2 > 300 mmHg group, 813 patients in the 201-300 mmHg group, 1 493 patients in the 101-200 mmHg group, and 1 003 patients in the ≤100 mmHg group. The severity scores of patients, including sequential organ failure assessment (SOFA) score and simplified acute physiology score II (SAPS II), gradually increased following the decrease in PaO2/FiO2, and the incidence of co-morbidities also gradually increased. In terms of ventilator parameters, mechanical power was increased gradually with decrease in PaO2/FiO2, measuring 10.4 (7.8, 13.9), 11.3 (8.5, 14.7), 13.6 (10.0, 18.2), and 16.7 (12.5, 22.0) J/min (P < 0.01). In terms of prognosis, 28-day mortality of patients was gradually increased with decrease in PaO2/FiO2 [29.1% (601/2 069), 26.9% (219/813), 28.1% (420/1 493), and 33.3% (334/1 003), respectively, P < 0.05]. In the heatmap, it could be observed that the 28-day death risk of mechanical ventilation patients was gradually increased with increase in mechanical power exposure intensity and long duration, showing two distinct areas: a region near the bottom left corner (representing low mechanical power exposure intensity and short duration) was blue, indicating a greater chance of survival. In contrast, another region near the top right corner (representing high mechanical power exposure intensity and long duration) was red, indicating a higher risk of death. According to the fitted lines of death risk, for the same risk of death, a shorter mechanical power exposure duration was required for higher exposure intensity, while lower mechanical power exposure intensity required a longer exposure duration. The above trend of change was similarly reflected in the overall population and different oxygenation populations. Cumulative mechanical power exposure to higher intensity and/or longer duration is associated with worse outcomes in mechanical ventilation patients. Considering both the mechanical power exposure intensity and duration may help to evaluate the effectiveness of lung protection in mechanical ventilation patients and guide adjustments in mechanical ventilation strategy to reduce the risk of ventilator-induced lung injury.

Effect of Ventilator Settings on Mechanical Power During Simulated Mechanical Ventilation of Patients With ARDS.

In recent years, mechanical power (MP) has emerged as an important concept that can significantly impact outcomes from mechanical ventilation. Several individual components of ventilatory support such as tidal volume (VT), breathing frequency, and PEEP have been shown to contribute to the extent of MP delivered from a mechanical ventilator to patients in respiratory distress/failure. The aim of this study was to identify which common individual setting of mechanical ventilation is more efficient in maintaining safe and protective levels of MP using different modes of ventilation in simulated subjects with ARDS. We used an interactive mathematical model of ventilator output during volume control ventilation (VCV) with either constant inspiratory flow (VCV-CF) or descending ramp inspiratory flow, as well as pressure control ventilation (PCV). MP values were determined for simulated subjects with mild, moderate, and severe ARDS; and whenever MP > 17 J/min, VT, breathing frequency, or PEEP was manipulated independently to bring back MP to ≤ 17 J/min. Finally, the optimum VT-breathing frequency combinations for MP = 17 J/min were determined with all 3 modes of ventilation. VCV-CF always resulted in the lowest MPs while PCV resulted in highest MPs. Reductions in VT were the most efficient for maintaining safer and protective MP. At targeted MPs of 17 J/min and maximized minute ventilation, the optimum VT-breathing frequency combinations were 250-350 mL for VT and 32-35 breaths/min for breathing frequency in mild ARDS, 200-350 mL for VT and 34-40 breaths/min for breathing frequency in moderate ARDS, and 200-300 mL for VT and 37-45 breaths/min for breathing frequency for severe ARDS. VCV-CF resulted in the lowest MP. VT was the most efficient for maintaining safe and protective MP in a mathematical simulation of subjects with ARDS. In the context of maintaining low and safe MPs, ventilatory strategies with lower-than-normal VT and higher-than-normal breathing frequency will need to be implemented in patients with ARDS.

Determinants of acute kidney injury during high-power mechanical ventilation: secondary analysis from experimental data

BackgroundThe individual components of mechanical ventilation may have distinct effects on kidney perfusion and on the risk of developing acute kidney injury; we aimed to explore ventilatory predictors of acute kidney failure and the hemodynamic changes consequent to experimental high-power mechanical ventilation.MethodsSecondary analysis of two animal studies focused on the outcomes of different mechanical power settings, including 78 pigs mechanically ventilated with high mechanical power for 48 h. The animals were categorized in four groups in accordance with the RIFLE criteria for acute kidney injury (AKI), using the end-experimental creatinine: (1) NO AKI: no increase in creatinine; (2) RIFLE 1-Risk: increase of creatinine of > 50%; (3) RIFLE 2-Injury: two-fold increase of creatinine; (4) RIFLE 3-Failure: three-fold increase of creatinine;ResultsThe main ventilatory parameter associated with AKI was the positive end-expiratory pressure (PEEP) component of mechanical power. At 30 min from the initiation of high mechanical power ventilation, the heart rate and the pulmonary artery pressure progressively increased from group NO AKI to group RIFLE 3. At 48 h, the hemodynamic variables associated with AKI were the heart rate, cardiac output, mean perfusion pressure (the difference between mean arterial and central venous pressures) and central venous pressure. Linear regression and receiving operator characteristic analyses showed that PEEP-induced changes in mean perfusion pressure (mainly due to an increase in CVP) had the strongest association with AKI.ConclusionsIn an experimental setting of ventilation with high mechanical power, higher PEEP had the strongest association with AKI. The most likely physiological determinant of AKI was an increase of pleural pressure and CVP with reduced mean perfusion pressure. These changes resulted from PEEP per se and from increase in fluid administration to compensate for hemodynamic impairment consequent to high PEEP;

Comprehensive study of mechanical power in controlled mechanical ventilation: Prevalence of elevated mechanical power and component analysis

ObjectiveTo determine the prevalence of elevated mechanical power (MP) values (>17J/min) used in routine clinical practice. DesignObservational, descriptive, cross-sectional, analytical, multicenter, international study conducted on November 21, 2019, from 8:00 AM to 3:00 PM. NCT03936231. SettingOne hundred thirty-three Critical Care Units. PatientsPatients receiving invasive mechanical ventilation for any cause. InterventionsNone. Main variables of interestMechanical power. ResultsA population of 372 patients was analyzed. PM was significantly higher in patients under pressure-controlled ventilation (PC) compared to volume-controlled ventilation (VC) (19.20±8.44J/min vs. 16.01±6.88J/min; p<0.001), but the percentage of patients with PM>17J/min was not different (41% vs. 35%, respectively; p=0.382). The best models according to AICcw expressing PM for patients in VC are described as follows: Surrogate Strain (Driving Pressure) + PEEP+Surrogate Strain Rate (PEEP/Flow Ratio) + Respiratory Rate. For patients in PC, it is defined as: Surrogate Strain (Expiratory Tidal Volume/PEEP) + PEEP+Surrogate Strain Rate (Surrogate Strain/Ti) + Respiratory Rate+Expiratory Tidal Volume+Ti. ConclusionsA substantial proportion of mechanically ventilated patients may be at risk of experiencing elevated levels of mechanical power. Despite observed differences in mechanical power values between VC and PC ventilation, they did not result in a significant disparity in the prevalence of high mechanical power values.

Impact of mechanical power and positive end expiratory pressure on central vs. mixed oxygen and carbon dioxide related variables in a population of female piglets.

The use of the pulmonary artery catheter has decreased overtime; central venous blood gases are generally used in place of mixed venous samples. We want to evaluate the accuracy of oxygen and carbon dioxide related parameters from a central versus a mixed venous sample, and whether this difference is influenced by mechanical ventilation. We analyzed 78 healthy female piglets ventilated with different mechanical power. There was a significant difference in oxygen-derived parameters between samples taken from the central venous and mixed venous blood (S O2 = 74.6%, ScvO2 = 83%, p < 0.0001). Conversely, CO2-related parameters were similar, with strong correlation. Ventilation with higher mechanical power and PEEP increased the difference between oxygen saturations, (Δ[ScvO2-S O2 ] = 7.22% vs. 10.0% respectively in the low and high MP groups, p = 0.020); carbon dioxide-related parameters remained unchanged (p = 0.344). The venous oxygen saturation (central or mixed) may be influenced by the effects of mechanical ventilation. Therefore, central venous data should be interpreted with more caution when using higher mechanical power. On the contrary, carbon dioxide-derived parameters are more stable and similar between the two sampling sites, independently of mechanical power or positive end expiratory pressures.

Adjustments of Ventilator Parameters during Operating Room-to-ICU Transition and 28-Day Mortality.

Rationale: Lung-protective mechanical ventilation strategies have been proven beneficial in the operating room (OR) and the ICU. However, differential practices in ventilator management persist, often resulting in adjustments of ventilator parameters when transitioning patients from the OR to the ICU. Objectives: To characterize patterns of ventilator adjustments during the transition of mechanically ventilated surgical patients from the OR to the ICU and assess their impact on 28-day mortality. Methods: Hospital registry study including patients undergoing general anesthesia with continued, controlled mechanical ventilation in the ICU between 2008 and 2022. Ventilator parameters were assessed 1 hour before and 6 hours after the transition. Measurements and Main Results: Of 2,103 patients, 212 (10.1%) died within 28 days. Upon OR-to-ICU transition, VT and driving pressure decreased (-1.1 ml/kg predicted body weight [IQR, -2.0 to -0.2]; P < 0.001; and -4.3 cm H2O [-8.2 to -1.2]; P < 0.001). Concomitantly, respiratory rates increased (+5.0 breaths/min [2.0 to 7.5]; P < 0.001), resulting overall in slightly higher mechanical power (MP) in the ICU (+0.7 J/min [-1.9 to 3.0]; P < 0.001). In adjusted analysis, increases in MP were associated with a higher 28-day mortality rate (adjusted odds ratio, 1.10; 95% confidence interval, 1.06-1.14; P < 0.001; adjusted risk difference, 0.7%; 95% confidence interval, 0.4-1.0, both per 1 J/min). Conclusion: During transition of mechanically ventilated patients from the OR to the ICU, ventilator adjustments resulting in higher MP were associated with a greater risk of 28-day mortality.

Intraoperative Mechanical Power and Postoperative Pulmonary Complications in Noncardiothoracic Elective Surgery Patients: A 10-Year Retrospective Cohort Study.

Postoperative pulmonary complications is a major issue that affects outcomes of surgical patients. The hypothesis was that the intraoperative ventilation parameters are associated with occurrence of postoperative pulmonary complications. A single-center retrospective cohort study was conducted at the Lille University Hospital, France. The study included 33,701 adults undergoing noncardiac, nonthoracic elective surgery requiring general anesthesia with tracheal intubation between January 2010 and December 2019. Intraoperative ventilation parameters were compared between patients with and without one or more postoperative pulmonary complications (respiratory infection, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm, and aspiration pneumonitis) within 7 days of surgery. Among 33,701 patients, 2,033 (6.0%) had one or more postoperative pulmonary complications. The lower tidal volume to predicted body weight ratio (odds ratio per -1 ml·kgPBW-1, 1.08; 95% CI, 1.02 to 1.14; P < 0.001), higher mechanical power (odds ratio per 4 J·min-1, 1.37; 95% CI, 1.26 to 1.49; P < 0.001), dynamic respiratory system compliance less than 30 ml·cm H2O (1.30; 95% CI, 1.15 to 1.46; P < 0.001), oxygen saturation measured by pulse oximetry less than 96% (odds ratio, 2.42; 95% CI, 1.97 to 2.96; P < 0.001), and lower end-tidal carbon dioxide (odds ratio per -3 mmHg, 1.06; 95% CI, 1.00 to 1.13; P = 0.023) were independently associated with postoperative pulmonary complications. Patients with postoperative pulmonary complications were more likely to be admitted to the intensive care unit (odds ratio, 12.5; 95% CI, 6.6 to 10.1; P < 0.001), had longer hospital length of stay (subhazard ratio, 0.43; 95% CI, 0.40 to 0.45), and higher in-hospital (subhazard ratio, 6.0; 95% CI, 4.1 to 9.0; P < 0.001) and 1-yr mortality (subhazard ratio, 2.65; 95% CI, 2.33 to 3.02; P < 0.001). In the study's population, decreased rather than increased tidal volume, decreased compliance, increased mechanical power, and decreased end-tidal carbon dioxide were independently associated with postoperative pulmonary complications.

Thermographic Changes following Short-Term High-Intensity Anaerobic Exercise.

Current studies report thermographic changes following aerobic or resistance exercise but not short, vigorous anaerobic exercise. Therefore, we investigated body surface temperature changes using thermal imaging following a short session of anaerobic exercise. We studied three different regions of interest (ROIs): the legs, chest, and forehead. Thermal imaging for each participant was performed before and immediately after completing a Wingate anaerobic test and every minute during a 15 min recovery period. Immediately after the test, the maximum temperature was significantly higher in all ROIs (legs, p = 0.0323; chest, p = 0.0455; forehead, p = 0.0444) compared to pre-test values. During the recovery period, both legs showed a significant and continuous temperature increase (right leg, p = 0.0272; left leg, p = 0.0382), whereas a non-significant drop was noted in the chest and forehead temperatures. Additionally, participants with a lower anaerobic capacity exhibited a higher delta increase in surface leg temperature than participants with higher anaerobic capacities, with a minimal change in surface leg temperature. This is the first study to demonstrate body surface temperature changes following the Wingate anaerobic test. This temperature increase is attributed to the high anaerobic mechanical power outputs achieved by the leg muscles and the time taken for temperature reduction post-exercise.

High Mechanical Power and Driving Pressures are Associated With Postoperative Respiratory Failure Independent From Patients' Respiratory System Mechanics.

High mechanical power and driving pressure (ΔP) have been associated with postoperative respiratory failure (PRF) and may be important parameters guiding mechanical ventilation. However, it remains unclear whether high mechanical power and ΔP merely reflect patients with poor respiratory system mechanics at risk of PRF. We investigated the effect of mechanical power and ΔP on PRF in cohorts after exact matching by patients' baseline respiratory system compliance. Hospital registry study. Academic hospital in New England. Adult patients undergoing general anesthesia between 2008 and 2020. None. The primary exposure was high (≥ 6.7 J/min, cohort median) versus low mechanical power and the key-secondary exposure was high (≥ 15.0 cm H 2 O) versus low ΔP. The primary endpoint was PRF (reintubation or unplanned noninvasive ventilation within seven days). Among 97,555 included patients, 4,030 (4.1%) developed PRF. In adjusted analyses, high intraoperative mechanical power and ΔP were associated with higher odds of PRF (adjusted odds ratio [aOR] 1.37 [95% CI, 1.25-1.50]; p < 0.001 and aOR 1.45 [95% CI, 1.31-1.60]; p < 0.001, respectively). There was large variability in applied ventilatory parameters, dependent on the anesthesia provider. This facilitated matching of 63,612 (mechanical power cohort) and 53,260 (ΔP cohort) patients, yielding identical baseline standardized respiratory system compliance (standardized difference [SDiff] = 0.00) with distinctly different mechanical power (9.4 [2.4] vs 4.9 [1.3] J/min; SDiff = -2.33) and ΔP (19.3 [4.1] vs 11.9 [2.1] cm H 2 O; SDiff = -2.27). After matching, high mechanical power and ΔP remained associated with higher risk of PRF (aOR 1.30 [95% CI, 1.17-1.45]; p < 0.001 and aOR 1.28 [95% CI, 1.12-1.46]; p < 0.001, respectively). High mechanical power and ΔP are associated with PRF independent of patient's baseline respiratory system compliance. Our findings support utilization of these parameters for titrating mechanical ventilation in the operating room and ICU.

Comparison of Eddy Current Coupling Topologies for High Efficiency Mechanical Power Transmission

The paper is an investigation into permanent magnet eddy current couplings for high efficiency power transmission. Through extensive simulation studies, the performance of radial- and axial-field topologies, employing squirrel cage and conducting sheets, are compared in terms of torque transmission density and efficiency of power transmission. It is shown, that although using a conducting sheet (as it is often the case) results in higher torque transmission density, employing a squirrel cage is more suitable for high efficiency power transmission. A prototype of the proposed radial-field single sided permanent magnet eddy current coupling employing a copper squirrel cage is developed and tested, and a good agreement between measurements and predictions is demonstrated.

Intensity of one-lung ventilation and postoperative respiratory failure: A hospital registry study

BackgroundStudies linked a high intensity of mechanical ventilation, measured as high mechanical power (MP) to postoperative respiratory failure (PRF) in the setting of two-lung ventilation. We investigated whether a higher MP during one-lung ventilation (OLV) is associated with PRF. MethodsIn this registry-based study, adult patients who underwent general anesthesia with OLV for thoracic surgeries between 2006 and 2020 at a New England tertiary healthcare network were included. The association between MP during OLV and PRF (emergency non-invasive ventilation or reintubation within seven days) was assessed in a cohort weighted through a generalized propensity score conditional on a priori defined preoperative and intraoperative factors. Dominance of components of MP and intensity of OLV versus two-lung ventilation in predicting PRF was investigated. ResultsOut of 878 included patients, 106 (12.1%) developed PRF. The median (IQR) MP during OLV was 9.8 J/min (7.5–11.8) and 8.3 J/min (6.6–10.2) in patients with and without PRF respectively. A higher MP during OLV was associated with PRF (ORadj 1.22 per 1 J/min increase; 95%CI 1.13–1.31; p < 0.001) and characterized by a U-shaped dose-response curve, with the lowest probability of PRF (7.5%) at 6.4 J/min. Dominance analysis of PRF predictors showed a stronger contribution of driving pressure over respiratory rate and tidal volume, the dynamic over the static component of MP, and MP during OLV over two-lung ventilation (contribution to Pseudo-R2: 0.017, 0.021, and 0.036, respectively). ConclusionA higher intensity of OLV, mainly driven by driving pressure, is dose-dependently associated with PRF and might constitute a target for mechanical ventilation.

Improving the Numbers, But Harming the Patient? The Authors Respond.

To the Editor: We thank da Costa et al.1 for their letter which makes some interesting observations. We agree that our study alone cannot be used to justify the use of extracorporeal membrane oxygenation (ECMO) as a strategy to protect the lungs in patients with moderate acute respiratory failure (ARF)—nor do we make a claim that it should. Severity of respiratory failure is not just defined by a single PaO2/FiO2 ratio value, but on a more complex clinical evaluation which must also take into account the duration of hypoxemia. We take this opportunity to stress that all patients in our study2 had ARF severe enough to receive ECMO based on the indications established by our national service. The “less severe” group had a median PaO2/FiO2 ratio of 105 mm Hg despite median FiO2 of 0.85, but fulfilled other criteria for ECMO. As this cohort was matched for PaCO2 with the “very severe” group, it is likely the price the patient has to pay for the PaO2/FiO2 ratio is injurious mechanical ventilation. Therefore, we would suggest that many of these patients would already meet criteria for ECMO in many systems, and that we are not advancing a “new” indication. There is now substantial evidence for the association between increased mechanical power, ventilator-induced lung injury and mortality in ARF,3 and in this context the use of ECMO allows the least damaging lung ventilation strategy4 and better outcomes.5 We would suggest, intuitively, that increased duration of high mechanical power to the lungs will thus increase mortality even if PaO2/FiO2 ratio is not yet “severe.” High mechanical power can—in the short term—increase PaO2/FiO2 masking the severity of disease, but ultimately increasing mortality. This was exactly what happened in the OSCILLATE Trial, where high-flow oscillatory ventilation resulted in better oxygenation but worse patient outcomes.6 The results of more recent studies are consistent with our findings: a large multinational cohort study of coronavirus patients suggested a survival benefit in those with PaO2/FiO2 ratio of 120–150 mm Hg.7 Da Costa et al. are correct also to identify the subset of ARF patients who experience acute right ventricular dysfunction, which is often exacerbated by “lung-protective” ventilation measures.8 Whether, or at what stage, such patients may benefit from ECMO support, is not a question our study can answer. The task then is how best to determine the answer to these questions? Do patients with “moderate-severe” respiratory failure benefit from ECMO? What about those with acute right ventricle (RV) dysfunction? Ultimately, we agree with da Costa et al. that in the absence of randomized controlled trials, the solution is in high-quality observational registries of ARF, not just of therapies such as ECMO, with advanced causal inference methods. For the individual patient, we suggest that the optimal strategy remains to identify the point at which the benefits of ECMO in preventing hypoxia and avoiding injurious lung ventilation outweigh its risks.

Utilization of mechanical power and associations with clinical outcomes in brain injured patients: a secondary analysis of the extubation strategies in neuro-intensive care unit patients and associations with outcome (ENIO) trial

BackgroundThere is insufficient evidence to guide ventilatory targets in acute brain injury (ABI). Recent studies have shown associations between mechanical power (MP) and mortality in critical care populations. We aimed to describe MP in ventilated patients with ABI, and evaluate associations between MP and clinical outcomes.MethodsIn this preplanned, secondary analysis of a prospective, multi-center, observational cohort study (ENIO, NCT03400904), we included adult patients with ABI (Glasgow Coma Scale ≤ 12 before intubation) who required mechanical ventilation (MV) ≥ 24 h. Using multivariable log binomial regressions, we separately assessed associations between MP on hospital day (HD)1, HD3, HD7 and clinical outcomes: hospital mortality, need for reintubation, tracheostomy placement, and development of acute respiratory distress syndrome (ARDS).ResultsWe included 1217 patients (mean age 51.2 years [SD 18.1], 66% male, mean body mass index [BMI] 26.3 [SD 5.18]) hospitalized at 62 intensive care units in 18 countries. Hospital mortality was 11% (n = 139), 44% (n = 536) were extubated by HD7 of which 20% (107/536) required reintubation, 28% (n = 340) underwent tracheostomy placement, and 9% (n = 114) developed ARDS. The median MP on HD1, HD3, and HD7 was 11.9 J/min [IQR 9.2–15.1], 13 J/min [IQR 10–17], and 14 J/min [IQR 11–20], respectively. MP was overall higher in patients with ARDS, especially those with higher ARDS severity. After controlling for same-day pressure of arterial oxygen/fraction of inspired oxygen (P/F ratio), BMI, and neurological severity, MP at HD1, HD3, and HD7 was independently associated with hospital mortality, reintubation and tracheostomy placement. The adjusted relative risk (aRR) was greater at higher MP, and strongest for: mortality on HD1 (compared to the HD1 median MP 11.9 J/min, aRR at 17 J/min was 1.22, 95% CI 1.14–1.30) and HD3 (1.38, 95% CI 1.23–1.53), reintubation on HD1 (1.64; 95% CI 1.57–1.72), and tracheostomy on HD7 (1.53; 95%CI 1.18–1.99). MP was associated with the development of moderate-severe ARDS on HD1 (2.07; 95% CI 1.56–2.78) and HD3 (1.76; 95% CI 1.41–2.22).ConclusionsExposure to high MP during the first week of MV is associated with poor clinical outcomes in ABI, independent of P/F ratio and neurological severity. Potential benefits of optimizing ventilator settings to limit MP warrant further investigation.

Mechanical power and 30-day mortality in mechanically ventilated, critically ill patients with and without Coronavirus Disease-2019: a hospital registry study

BackgroundPrevious studies linked a high intensity of ventilation, measured as mechanical power, to mortality in patients suffering from “classic” ARDS. By contrast, mechanically ventilated patients with a diagnosis of COVID-19 may present with intact pulmonary mechanics while undergoing mechanical ventilation for longer periods of time. We investigated whether an association between higher mechanical power and mortality is modified by a diagnosis of COVID-19.MethodsThis retrospective study included critically ill, adult patients who were mechanically ventilated for at least 24 h between March 2020 and December 2021 at a tertiary healthcare facility in Boston, Massachusetts. The primary exposure was median mechanical power during the first 24 h of mechanical ventilation, calculated using a previously validated formula. The primary outcome was 30-day mortality. As co-primary analysis, we investigated whether a diagnosis of COVID-19 modified the primary association. We further investigated the association between mechanical power and days being alive and ventilator free and effect modification of this by a diagnosis of COVID-19. Multivariable logistic regression, effect modification and negative binomial regression analyses adjusted for baseline patient characteristics, severity of disease and in-hospital factors, were applied.Results1,737 mechanically ventilated patients were included, 411 (23.7%) suffered from COVID-19. 509 (29.3%) died within 30 days. The median mechanical power during the first 24 h of ventilation was 19.3 [14.6–24.0] J/min in patients with and 13.2 [10.2–18.0] J/min in patients without COVID-19. A higher mechanical power was associated with 30-day mortality (ORadj 1.26 per 1-SD, 7.1J/min increase; 95% CI 1.09–1.46; p = 0.002). Effect modification and interaction analysis did not support that this association was modified by a diagnosis of COVID-19 (95% CI, 0.81–1.38; p-for-interaction = 0.68). A higher mechanical power was associated with a lower number of days alive and ventilator free until day 28 (IRRadj 0.83 per 7.1 J/min increase; 95% CI 0.75–0.91; p < 0.001, adjusted risk difference − 2.7 days per 7.1J/min increase; 95% CI − 4.1 to − 1.3).ConclusionA higher mechanical power is associated with elevated 30-day mortality. While patients with COVID-19 received mechanical ventilation with higher mechanical power, this association was independent of a concomitant diagnosis of COVID-19.

Indications for extracorporeal membrane oxygenation in coronavirus disease 2019: is the Berlin definition still adequate to adjust therapeutic interventions? A case report

Indications for extracorporeal membrane oxygenation in coronavirus disease 2019: is the Berlin definition still adequate to adjust therapeutic interventions? A case report

AS DIFERENÇAS ENTRE OS MODOS MODERNOS DE TREINAMENTO DE BIATLO NOS JOGOS OLÍMPICOS DE INVERNO

ABSTRACT Introduction The biathlon is a snow sport that combines cross-country skiing and shooting, originating in Scandinavia. It requires athletes to not only have the ability to glide quickly over long distances but also to have the ability to shoot quickly and accurately. There is little research on biathlon characteristics and analysis of influencing factors and training strategies in China. Objective This study analyzes modern biathlon athletes’ specific explosive power, endurance and training effects at the Winter Olympics. Methods Twenty biathlon athletes were selected as research volunteers. Physiological and biochemical indicators of the athletes were experimentally tested after training. Results There was a correlation between maximum speed and the height of the athletes’ double stand test (SD) (p &lt; 0.05). The heavier athletes skied relatively faster. However, the excessive body fat rate is not conducive to maintaining high-intensity skiing in the long term. The athletes’ VO2max was closely related to their skiing performance and shot hit percentage (p &lt; 0.05). Conclusion Maintaining gun ski training can positively improve the competitive level of world-class biathletes. The athlete's muscles have a solid ability to generate high mechanical power in a short time. It is beneficial to take advantage of a favorable position after the start of the competition. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Mechanical spring discharge-based multipillar triboelectric nanogenerator with enhanced power output

With the extensive use of small portable electronics in digital healthcare, the triboelectric nanogenerator (TENG), which can convert mechanical energy into electricity, has been developed for these portable electronics. However, the high mechanical input power for TENG performance improvement causes constant damage and excessive noise, which can make applying portable devices in daily life inconvenient. Nevertheless, the TENG electrical limitation, generating a low current output as nanoampere to microampere, still is not overcome. In this study, a portable multipillar TENG (PMP-TENG) with conductive springs can provide amplified output, developed mechanical characteristics simultaneously. When a moving electrode with a surface charge contacts the springs, the PMP-TENG continuously generates a high discharge output and increases the output frequency through the elastic force of the spring. In addition, the spring can prevent crack damage and harmful noise via shock absorption of the moving electrode. During the PMP-TENG operating mechanical input of 2.5 Hz, the average peak voltage, current is 165 V, 34 mA, respectively. The PMP-TENG is used to charge small electronics or power warning lights in portable devices during human motion, such as walking, running, and jumping, increasing its advantages.

Latent class analysis of imaging and clinical respiratory parameters from patients with COVID-19-related ARDS identifies recruitment subphenotypes

BackgroundPatients with COVID-19-related acute respiratory distress syndrome (ARDS) require respiratory support with invasive mechanical ventilation and show varying responses to recruitment manoeuvres. In patients with ARDS not related to COVID-19, two pulmonary subphenotypes that differed in recruitability were identified using latent class analysis (LCA) of imaging and clinical respiratory parameters. We aimed to evaluate if similar subphenotypes are present in patients with COVID-19-related ARDS.MethodsThis is the retrospective analysis of mechanically ventilated patients with COVID-19-related ARDS who underwent CT scans at positive end-expiratory pressure of 10 cmH2O and after a recruitment manoeuvre at 20 cmH2O. LCA was applied to quantitative CT-derived parameters, clinical respiratory parameters, blood gas analysis and routine laboratory values before recruitment to identify subphenotypes.Results99 patients were included. Using 12 variables, a two-class LCA model was identified as best fitting. Subphenotype 2 (recruitable) was characterized by a lower PaO2/FiO2, lower normally aerated lung volume and lower compliance as opposed to a higher non-aerated lung mass and higher mechanical power when compared to subphenotype 1 (non-recruitable). Patients with subphenotype 2 had more decrease in non-aerated lung mass in response to a standardized recruitment manoeuvre (p = 0.024) and were mechanically ventilated longer until successful extubation (adjusted SHR 0.46, 95% CI 0.23–0.91, p = 0.026), while no difference in survival was found (p = 0.814).ConclusionsA recruitable and non-recruitable subphenotype were identified in patients with COVID-19-related ARDS. These findings are in line with previous studies in non-COVID-19-related ARDS and suggest that a combination of imaging and clinical respiratory parameters could facilitate the identification of recruitable lungs before the manoeuvre.