Ventilatory Variables Research Articles

The Cardiorespiratory Coupling as a Background for Blood Pressure Decrease

The role of cardiorespiratory coupling cannot be overemphasized. Cardiorespiratory coupling has many potential benefits in maintaining homeostasis. One of manifestation of cardiorespiratory coupling is respiratory sinus arrhythmia observed at respiratory rate 6 breaths/ minute. Multiple factors, including mechanical coupling, are responsible for the fluctuation of HR and BP. However, the fine mechanisms of the autonomic, cardiovascular, and respiratory interactions till now remains unclear.A total of 156 international students were recruited from the V.N. Karazin Kharkiv National University. The sitting position was taken as a baseline according to requirements of the spirometry system. The ECG was continuously recorded at the rest and during slow breathing at 6 breaths/minute. The respiratory rate (RR) and tidal volume (TV) were recorded at the end of each stage for one minute using SPIROCOM pc based systems (XAI‐Medica, Ukraine). Systolic and diastolic blood pressure (SBP and DBP) were recorded by means automatic digital sphygmomanometer (OMRON EVOLV, Japan). The low and high frequency heart rate variability (LF and HF HRV) power were computed with CardioLab CS by fast Fourier transforming. The repeated measures MANOVA with Bonferroni correction (SPSS 22) was used to test for effects of slow breathing on HR, SBP, DBP, LnLF, LnHF, tidal volume (TV), minute ventilation (MV), and RR variables. Predictors of HR, SBP, DBP, TV, MV., and RR to slow breathing were determined using stepwise multiple linear regression analysis. Written informed consent was obtained from each participant.In the current study the slowing respiratory rate to 6 breaths/min increased HR (P<0.001) (not shown), decreased SBP (P<0.001), decreased DBP (P=0.003), increased LnLF (P<0001), increased TV (P<0.001), and decreased RR (not shown, Р<0.001). The stepwise multiple linear regression analysis revealed that at rest HR and RR were negatively associated with LnHF power (Table 1, P<0.001 for both), while at slow breathing stage the HR was negatively associated with both LnHF and LnLF power (Table 2, P<0.001 and P=0.004, respectively). If the HF power is widely used as an index of cardiovagal activity, interpretation of the LF power is more controversal. We proceeded from our hypothesis that LF HRV power is a measure of baroreflex‐mediated sympathoinhibition. At rest both SBP and DBP were positively associated with LnLF by LnHF interaction, while at slow breathing stage they were negatively associated only with LnLF power. The resting TV and MV were positively associated with LnLF power, also, the MV with LnHF by height and BMI interaction. But at slow breathing stage only the height and BMI were independent variables remaining in these models (Table 2, Models 4 and 5).Taken together, these findings indicate that the same autonomic variables control respiratory function in parallel with cardiovascular system.

Toodler ISPA in a Brick Environment

Acute Respiratory Tract Infection (ISPA) is still the dominant factor in patient visits to the puskesmas as a primary health care unit. The phenomenon of the incidence of ISPA caused by multiple factors is a challenge for health workers. Environmental factors are often considered elements that do not have a major role in the incidence of ISPA cases. Ironically, environmental factors have also been neglected in the effort to handle ISPA cases. Candirejo village is an area with the economic characteristics of the community as a producer of bricks. This study aims to see the relationship between ISPA with independent variables (dust, occupancy density, house ventilation, lighting and humidity). This research is quantitative with a cross sectional design in order to see the environmental and physical factors of the house on the incidence of ISPA in toddlers. This study took a sample of 100 households with children under five. This research is expected to be a new evidence related to environmental and physical factors of the house on the incidence of ISPA in toddlers. Variables that are significantly related to the incidence of ARI are house ventilation and residential density variables. The study found that humidity as a confounding factor. The results of the analysis obtained that the OR of the house ventilation variable that did not meet the requirements would cause the occurrence of ISPA in children under five at 16 times more risk than the ventilation of the house that met the requirements after controlling for the humidity variable. It is suggested to the puskesmas through sanitarian staff to carry out Information Communication and Education (KIE) activities about ISPA during the posyandu implementation.

Comparison between determination of second anaerobic threshold by respiratory compensating point and X-method in rowers

Background and Study Aim. The aim of this study is to verify the X-method for determining the second anaerobic threshold in rowers.Material and Methods. Twelve male athletes from the national rowing team of Bulgaria were tested. Participants performed a one-time graded incremental exercise test to exhaustion on a rowing ergometer. The workload were conducted on rowing ergometer system Concept 2, and spirometry system Clark C5. We obtained ventilatory indices, intensity and heart rate bred-by-bred for each participant, for each test stage. The anaerobic threshold was determined by two methods: 1) by the localization of the respiratory compensation point visually, after polynomial regression analysis of the trends for the dynamics of the ventilatory variables related to time and 2) by the X-method using the change in the ratio between heart rate and pulmonary ventilation. We compared the heart rate corresponding to the anaerobic threshold determined by both methods.Results. We found similar values for heart rate at the respiratory compensation point and the anaerobic threshold determined by the X-method for each of the investigated. The Shapiro-Wilk test showed a normal distribution of the two samples with a significance level of α = 0.05. Thus, the t-test for two paired samples showed a p-value of 0.202 at α = 0.05. We found a correlation coefficient r = 0.973 between the heart rate at the anaerobic threshold (determined by X-method) and the heart rate at the anaerobic threshold (detected at the respiratory compensation point). The Blant-Altman analysis showed that 95% of the points in the scatter plot lie within the confidence interval.Conclusions. The two methods give similar results and can be applied alternatively in the investigation of rowers in the age group 18.3 ± 1.07 years. The X-method always gives a reliable intersection point, which in our studies is close to the second anaerobic threshold. Comparative studies are also needed in other contingents for the wider use of the X-method.

Effect of Automated Closed-loop ventilation versus convenTional VEntilation on duration and quality of ventilation in critically ill patients (ACTiVE) \u2013 study protocol of a randomized clinical trial

BackgroundINTELLiVENT–Adaptive Support Ventilation (ASV) is a fully automated closed-loop mode of ventilation for use in critically ill patients. Evidence for benefit of INTELLiVENT–ASV in comparison to ventilation that is not fully automated with regard to duration of ventilation and quality of breathing is largely lacking. We test the hypothesis that INTELLiVENT–ASV shortens time spent on a ventilator and improves the quality of breathing.MethodsThe “Effects of Automated Closed–loop VenTilation versus Conventional Ventilation on Duration and Quality of Ventilation” (ACTiVE) study is an international, multicenter, two-group randomized clinical superiority trial. In total, 1200 intensive care unit (ICU) patients with an anticipated duration of ventilation of > 24 h will be randomly assigned to one of the two ventilation strategies. Investigators screen patients aged 18 years or older at start of invasive ventilation in the ICU. Patients either receive automated ventilation by means of INTELLiVENT–ASV, or ventilation that is not automated by means of a conventional ventilation mode. The primary endpoint is the number of days free from ventilation and alive at day 28; secondary endpoints are quality of breathing using granular breath-by-breath analysis of ventilation parameters and variables in a time frame of 24 h early after the start of invasive ventilation, duration of ventilation in survivors, ICU and hospital length of stay (LOS), and mortality rates in the ICU and hospital, and at 28 and 90 days.DiscussionACTiVE is one of the first randomized clinical trials that is adequately powered to compare the effects of automated closed-loop ventilation versus conventional ventilation on duration of ventilation and quality of breathing in invasively ventilated critically ill patients. The results of ACTiVE will support intensivist in their choices regarding the use of automated ventilation.Trial registrationACTiVE is registered in clinicaltrials.gov (study identifier: NCT04593810) on 20 October 2020.

Cannabinoid Receptor mRNA Expression in Central and Peripheral Tissues in a Rodent Model of Peritonitis.

Introduction: Our laboratory investigates changes in the respiratory pattern during systemic inflammation in various rodent models. The endogenous cannabinoid system (ECS) regulates cytokine production and mitigates inflammation. Inflammation not only affects cannabinoid (CB) 1 and CB2 receptor gene expression (Cnr1 and Cnr2), but also increases the predictability of the ventilatory pattern. Objectives: Our primary objective was to track ventilatory pattern variability and transcription of Cnr1 and Cnr2 mRNA, and of Il1b, Il6, and tumor necrosis factor-alpha (Tnfa) mRNAs at multiple time points in central and peripheral tissues during systemic inflammation induced by peritonitis. Methods: In male Sprague Dawley rats (n=24), we caused peritonitis by implanting a fibrin clot containing either 0 or 25×106 Escherichia coli intraperitoneally. We recorded breathing with whole-animal plethysmography at baseline and 1 h before euthanasia. We euthanized the rats at 3, 6, or 12 h after inoculation and harvested the pons, medulla, lung, and heart for gene expression analysis. Results: With peritonitis, Cnr1 mRNA more than Cnr2 mRNA was correlated to Il1b, Il6, and Tnfa mRNAs in medulla, pons, and lung and changed oppositely in the pons, medulla, and lung. These changes were associated with increased predictability of ventilatory pattern. Specifically, nonlinear complexity index correlated with increased Cnr1 mRNA in the pons and medulla, and coefficient of variation for cycle duration correlated with Cnr1 and Cnr2 mRNAs in the lung. Conclusion: The mRNAs for ECS receptors varied with time during the central and peripheral inflammatory response to peritonitis. These changes occurred in the brainstem, which contains the network that generates breathing pattern and thus, may participate in ventilatory pattern changes during systemic inflammation.

Influence of Step Frequency on the Dynamic Characteristics of Ventilation and Gas Exchange During Sinusoidal Walking in humans

We tested the hypothesis that restricting either step frequency (SF) or stride length (SL) causes a decrease in ventilatory response with limited breath frequency during sinusoidal walking. In this study, 13 healthy male and female volunteers (mean ± SD; age: 21.5 ± 1.8 years, height: 168 ± 7 cm, weight: 61.5 ± 8.3 kg) participated. The walking speed was sinusoidally changed between 50 and 100 m⋅min–1 with periods from 10 to 1 min. Using a customized sound system, we fixed the SF at 120 steps⋅min–1 with SL variation (0.83–0.41 m) (SFfix) or fixed the SL at 0.7 m with SF variation (143–71 steps⋅min–1) (SLfix) during the subjects’ sinusoidal walking. Both the subjects’ preferred locomotion pattern without a sound system (Free) and the unprompted spontaneous locomotor pattern for each subject (Free) served as the control condition. We measured breath-by-breath ventilation [tidal volume (VT) and breathing frequency (Bf)] and gas exchange [CO2 output (CO2), O2 uptake (O2)]. The amplitude (Amp) and the phase shift (PS) of the fundamental component of the ventilatory and gas exchange variables were calculated. The results revealed that the SFfix condition decreased the Amp of the Bf response compared with SLfix and Free conditions. Notably, the Amp of the Bf response under SFfix was reduced by less than one breath at the periods of 5 and 10 min. In contrast, the SLfix condition resulted in larger Amps of Bf and E responses as well as Free. We thus speculate that the steeper slope of the E-CO2 relationship observed under the SLfix might be attributable to the central feed-forward command or upward information from afferent neural activity by sinusoidal locomotive cadence. The PSs of the E, O2, and CO2 responses were unaffected by any locomotion patterns. Such a sinusoidal wave manipulation of locomotion variables may offer new insights into the dynamics of exercise hyperpnea.

Exergy analysis and optimisation of an industrial-scale circulation counter-flow paddy drying process

Drying is a process of removing water from products down to a specific moisture content. It is an energy-intensive process widely-used for grain and biomass processing. Because of the complicated thermodynamics and transport phenomena involved in drying, it is challenging to analyse and optimise drying operations. In this study, computer simulations using a transient model are performed to simulate the real-time paddy drying, and analyse the exergy components, exergy efficiency, exergy loss and destruction of industrial-scale drying process under changing drying air temperature (60–80 °C) and flow velocity (0.56–0.83 m/s) and initial moisture content (0.22–0.3 g water/g wet matter) on a circulation counter-flow paddy dryer. Results show our model can predict paddy moisture content and temperature with mean relative deviations of 5.5% and 1.42%, respectively. Exergy efficiency of drying process is specified to be in the range of 28.75–35.68%. Main factor affecting drying rate and energy consumption in high moisture content regions of drying process is drying air flow velocity while that in low moisture content regions is drying air temperature. We also propose control strategy based on two-stage variable ventilation parameters that achieves high exergy utilization level, high drying rate, and high product quality for grain drying.

Wildfire-resilient mechanical ventilation systems for single-detached homes in cities of Western Canada

The increasing prevalence and severity of wildfire events around the world have emphasized the importance of wildfire resiliency in indoor environmental design. This study focuses on developing wildfire-resilient mechanical ventilation systems and ventilation strategies for application in single-detached residences in western Canada. Outdoor PM2.5 concentration datasets during wildfire conditions were used in conjunction with indoor air quality (IAQ) mathematical models to assess the impact of ventilation and building-related input variables on indoor PM2.5 levels. A cost-benefit analysis was conducted to compare the cost of ventilation retrofit options with regional estimates of reasonable monetary contributions per resident towards health risk mitigation. Ventilation retrofit options were recommended based on IAQ simulations, model sensitivity, and cost-benefit analysis results. It was recommended that residential ventilation systems increase the minimum filter efficiency from MERV6 to MERV11 or MERV13 during wildfire operation and implement higher recirculation ratios during peak exposure scenarios. Multi-filter mechanical ventilation system configurations were recommended for residential dwellings located in regions prone to severe PM2.5 exposure. This study provides insight into the integration of wildfire-resiliency in existing residential mechanical ventilation systems for indoor air quality improvement. This work sets the foundation for future experimental verification of the performance of ventilation strategies to improve urban safety, health and wellness in wildfire conditions.

Clinical characteristics, respiratory management, and determinants of oxygenation in COVID-19 ARDS: A prospective cohort study.

PurposeTo identify determinants of oxygenation over time in patients with COVID-19 acute respiratory distress syndrome (ARDS); and to analyze their characteristics according to Berlin definition categories.Materials and methodsProspective cohort study including consecutive mechanically ventilated patients admitted between 3/20/2020–10/31/2020 with ARDS. Epidemiological and clinical data on admission; outcomes; ventilation, respiratory mechanics and oxygenation variables were registered on days 1, 3 and 7 for the entire population and for ARDS categories.Results1525 patients aged 61 ± 13, 69% male, met ARDS criteria; most frequent comorbidities were obesity, hypertension, diabetes and respiratory disease. On admission, 331(21%), 849(56%) and 345(23%) patients had mild, moderate and severe ARDS; all received lung-protective ventilation (mean tidal volumes between 6.3 and 6.7 mL/kg PBW) and intermediate PEEP levels (10–11 cmH2O). PaO2/FiO2, plateau pressure, static compliance, driving pressure, ventilation ratio, pH and D-dimer >2 mg/L remained significantly different among the ARDS categories over time. In-hospital mortality was, respectively, 55%, 58% and 70% (p < 0.000). Independent predictors of changes of PaO2/FiO2 over time were BMI; preexistent respiratory disease; D-dimer >2 mg/L; day 1-PEEP, and day 1-ventilatory ratio.ConclusionHypoxemia in patients with COVID-19-related ARDS is associated with comorbidities, deadspace and activated coagulation markers, and disease severity—reflected by the PEEP level required.

Effectiveness of an adapted diving mask (Owner mask) for non-invasive ventilation in the COVID-19 pandemic scenario: study protocol for a randomized clinical trial

BackgroundNon-invasive ventilation (NIV) is indicated to avoid orotracheal intubation (OTI) to reduce hospital stay and mortality. Patients infected by SARS-CoV2 can progress to respiratory failure (RF); however, in the initial phase, they can be submitted to oxygen therapy and NIV. Such resources can produce aerosol and can cause a high risk of contagion to health professionals. Safe NIV strategies are sought, and therefore, the authors adapted diving masks to be used as NIV masks (called an Owner mask).ObjectiveTo assess the Owner mask safety and effectiveness regarding conventional orofacial mask for patients in respiratory failure with and without confirmation or suspicion of COVID-19.MethodsA Brazilian multicentric study to assess patients admitted to the intensive care unit regarding their clinical, sociodemographic and anthropometric data. The primary outcome will be the rate of tracheal intubation, and secondary outcomes will include in-hospital mortality, the difference in PaO2/FiO2 ratio and PaCO2 levels, time in the intensive care unit and hospitalization time, adverse effects, degree of comfort and level of satisfaction of the mask use, success rate of NIV (not progressing to OTI), and behavior of the ventilatory variables obtained in NIV with an Owner mask and with a conventional face mask. Patients with COVID-19 and clinical signs indicative of RF will be submitted to NIV with an Owner mask [NIV Owner COVID Group (n = 63)] or with a conventional orofacial mask [NIV orofacial COVID Group (n = 63)], and those patients in RF due to causes not related to COVID-19 will be allocated into the NIV Owner Non-COVID Group (n = 97) or to the NIV Orofacial Non-COVID Group (n = 97) in a randomized way, which will total 383 patients, admitting 20% for loss to follow-up.DiscussionThis is the first randomized and controlled trial during the COVID-19 pandemic about the safety and effectiveness of the Owner mask compared to the conventional orofacial mask. Experimental studies have shown that the Owner mask enables adequate sealing on the patient’s face and the present study is relevant as it aims to minimize the aerosolization of the virus in the environment and improve the safety of health professionals.Trial registrationBrazilian Registry of Clinical Trials (ReBEC): RBR – 7xmbgsz. Registered on 15 April 2021.

Novel SEPN1 Mutations in Exon 1 Are Common in Rigid Spine With Muscular Dystrophy Type 1 in Chinese Patients.

Congenital muscular dystrophy with early rigid spine, also known as the rigid spine with muscular dystrophy type 1 (RSMD1), is caused by SEPN1 mutation. We investigated the clinical manifestations, pathological features, and genetic characteristics of 8 Chinese RSMD1 patients in order to improve diagnosis and management of the disease. Eight patients presented with delayed motor development, muscle weakness, hypotonia, and a myopathic face with high palatine arches. All patients could walk independently, though with poor running and jumping, and most had a rigid spine, lordosis, or scoliosis. The symptoms of respiratory involvement were present early, and upper respiratory tract infections and pneumonia often occurred. Five patients had severe pneumonia, pulmonary hypertension, and respiratory failure. Lung function tests showed variable restrictive ventilation dysfunction. Polysomnography suggested hypoxia and hypoventilation. The serum creatine kinase (CK) level was normal or mildly increased. Muscle biopsy indicated chronic myopathic changes and minicores. Muscle magnetic resonance imaging (MRI) showed diffuse fatty infiltration of the gluteus maximus and thigh muscle. SEPN1 gene analysis revealed 16 compound heterozygous variants, 81.3% of which are unreported, including 7 exon 1 variants. Our study expands the spectrum of clinical and genetic findings in RSMD1 to improve diagnosis, management, and standards of care. SEPN1 mutations in exon 1 are common and easily missed, and exon 1 should be carefully analyzed when RSMD1 is suspected, which will provide valuable genetic counseling for the family and useful information for future natural history studies and clinical trials.

Patient-Ventilator Synchrony in Neurally-Adjusted Ventilatory Assist and Variable Pressure Support Ventilation.

Neurally-adjusted ventilatory assist (NAVA) improves patient-ventilator synchrony and reduces the risk of respiratory over-assistance. Variable pressure support ventilation (PSV) is a recently introduced mode of assisted ventilation that has also shown reduction in patient-ventilator asynchronies. We hypothesized that NAVA would reduce patient-ventilator asynchronies and inspiratory effort compared to variable PSV because breathing variability was intrinsically determined by the patient and not by the ventilator. This study aimed to evaluate patient-ventilator asynchronies and inspiratory effort pressure-time product (PTP) between NAVA and variable PSV in subjects with mild ARDS. After 24 h of controlled mechanical ventilation, subjects (PaO2 /FIO2 200-300 and PEEP level < 10 cm H2O) were randomized in sequence 1:1 by using a web-based encrypted platform and assigned to NAVA or variable PSV groups. Both modes of ventilation were consecutively kept for 24 h unless there were clinical changes. The primary aim of this study was to evaluate differences in asynchrony index (AI) between variable PSV and NAVA. Our secondary aims were to evaluate the coefficient of variation (CV) of breathing patterns and inspiratory effort between the groups. Thirteen subjects were randomized in the NAVA group and 13 subjects in the variable PSV group. AI over time and minute PTP (PTPmin) were not different between NAVA and variable PSV groups (AI t0P = .52, AI t12P = .27, AI t24P = .12; and PTPmin-t0P = .60, PTPmin-t12P = .57, PTPmin-t24P = .85, respectively). CV for tidal volume (VT) and pressure support (PS) was lower in variable PSV group over time compared with NAVA group (P < .05). In this randomized controlled trial including subjects with mild ARDS, NAVA and variable PSV had comparable effects on patient-ventilator synchronies and PTP. However, variable PSV reduced the variability of VT and PS when compared with NAVA.

Predicting Impact of Prone Position on Oxygenation in Mechanically Ventilated Patients with COVID-19.

ObjectivesProne positioning is widely used in mechanically ventilated patients with COVID-19; however, the specific clinical scenario in which the individual is most poised to benefit is not fully established. In patients with COVID-19 respiratory failure requiring mechanical ventilation, how effective is prone positioning in improving oxygenation and can that response be predicted?DesignThis is a retrospective observational study from two tertiary care centers including consecutive patients mechanically ventilated for COVID-19 from 3/1/2020 – 7/1/2021. The primary outcome is improvement in oxygenation as measured by PaO2/FiO2. We describe oxygenation before, during and after prone episodes with a focus on identifying patient, respiratory or ventilator variables that predict prone positioning success.Setting2 Tertiary Care Academic HospitalsPatients125 patients mechanically ventilated for COVID-19 respiratory failure.InterventionsProne positioningMain ResultsOne hundred twenty-five patients underwent prone positioning a total of 309 times for a median duration of 23 hours IQR (14 – 49). On average, PaO2/FiO2 improved 19%: from 115 mm Hg (80 – 148) immediately before proning to 137 mm Hg (95 – 197) immediately after returning to the supine position. Prone episodes were more successful if the pre-prone PaO2/FiO2 was lower and if the patient was on inhaled epoprostenol (iEpo). For individuals with severe acute respiratory distress syndrome (ARDS) (PaO2/FiO2 < 100 prior to prone positioning) and on iEpo, the median improvement in PaO2/FiO2 was 27% in both instances.ConclusionsProne positioning in mechanically ventilated patients with COVID-19 is generally associated with sustained improvements in oxygenation, which is made more likely by the concomitant use of iEpo and is more impactful in those who are more severely hypoxemic prior to prone positioning.

Cardiopulmonary exercise testing in patients with asymptomatic left ventricular dysfunction: lack of prognostic predictive power of ventilatory variables.

The indication for cardiopulmonary exercise testing (CPET) in predictive evaluation has been extended beyond chronic heart failure (HF) patients to include asymptomatic left ventricular dysfunction (ALVD) patients, but its prognostic value is still unclear. We aimed to verify if CPET can predict outcome in ALVD and to identify which of the CPET parameters predictive in chronic HF are also effective in ALVD patients. We screened ALVD (LVEF ≤ 40% without HF symptoms) and HF patients for cardiac death, and compared peak oxygen consumption (pVO2), exertional oscillatory ventilation (EOV), and ventilatory response (VE/VCO2 slope) between survivors and non-survivors. Asymptomatic left ventricular dysfunction and HF patients formed the study population (585 ALVD and 695 HF). Both groups had similar male prevalence (98% vs. 98%; P = 0.345) but ALVD patients were younger (52 ± 10 vs. 60 ± 10 years, P = 0.004). Cardiac death was observed in 142 patients (5% of ALVD, 15% of HF). Exertional oscillatory ventilation occurred in 4% of ALVD, whereas VE/VCO2 slope was significantly lower (30 ± 7 vs. 35 ± 4) and pVO2 higher (16 ± 4 vs. 14 ± 3 mL/kg/min) than in chronic HF patients. Asymptomatic left ventricular dysfunction non-survivors had a significantly greater EOV incidence (13% vs. 3%, P = 0.003), lower pVO2 (13 ± 4 vs. 16 ± 3 mL/kg/min P = 0.000) and higher VE/VCO2 slope (33 ± 7 vs. 31 ± 5, P = 0.032). No ventilatory parameter had prognostic value at multivariable analysis in ALVD patients. Cardiopulmonary exercise testing can predict events in ALVD patients, but the risk stratification relies on different parameters than in HF patients. Further analysis in a multi-centre trial is required to better quantify the predictive impact of CPET risk parameters in ALVD patients.

Indications and outcome associated with positive-pressure ventilation in dogs and cats: 127 cases.

To determine the indications and outcomes of positive-pressure ventilation (PPV) and identify factors associated with successful weaning. Retrospective study from October 2009 to September 2013. University teaching hospital. One hundred and eleven dogs and 16 cats. Medical records were retrospectively reviewed; signalment, indication for PPV, patient characteristics, blood gas, and ventilator variables during PPV, duration of PPV, and outcome were recorded. Dogs were most commonly ventilated for pneumonia (36/111; 32%) and cats for multiple pulmonary diseases (8/16; 50%). The median duration of PPV for all animals was 25.7h (range, 0.1-957h). Long-term PPV (≥24h) was performed in 53% of cases. No differences were noted in successful weaning rates between cases ventilated for pulmonary etiologies (23/99; 23%) versus nonpulmonary etiologies (9/28; 32%). Overall, 32 of 127 (25%; 30 dogs, 2 cats) animals were successfully weaned from PPV and 28 of 127 (22%; 26 dogs, 2 cats) survived to hospital discharge. Long-term ventilation had a higher likelihood of successful weaning (26/67 [39%] vs 6/60 [10%], P=0.0002) and higher rates of survival to discharge (23/67 [34%] vs 5/60 [8%], P=0.0005) than short-term ventilation. Animals with higher Pao2 /Fio2 and Spo2 /Fio2 and lower APPLE and SOFA scores on day 1 of PPV were more likely to be weaned (P<0.03). The outcome of PPV appears to be most heavily determined by the underlying disease process and no clear improvement in outcome could be demonstrated in this study, despite advances in veterinary critical care and ventilator management strategies since previous studies. Dogs and cats receiving PPV for more than 24h in this study had a higher likelihood of a positive outcome. Several indices of oxygenation and illness severity at the onset of PPV were predictive of outcome and maybe useful when considering prognosis of these cases.

Causal validation of the risk for corneal injury in critically ill adults.

The validity of a nursing diagnosis depends on a continuous investigation process in different populations to provide clinical evidence. The risk for corneal injury nursing diagnosis was approved in 2013 and only reviewed in 2017, demonstrating the need to perform a clinical validation to improve it. To perform a causal validation of the risk for corneal injury nursing diagnosis in critically ill adults. A prospective cohort study was performed in two intensive critical care units in Northern Brazil with adults aged over 18 years without corneal injury at admission. The patients were evaluated for 10 days, using a data collection tool composed of risk factors for the risk for corneal injury nursing diagnosis. The independent variables were described through absolute and relative frequency. The accuracy measures and risk factors were identified through Cox regression, considering a 95% confidence interval. The nurses assessed 209 critically ill adults and identified that 76.0% of them presented the risk for corneal injury nursing diagnosis, with 16.3% developing a corneal injury, all having previously presented the risk for corneal injury nursing diagnosis. The risk factors identified were eyeball exposure (hazard ratio: 1.78; 95% CI: 1.27-2.51), Glasgow score < 6 (hazard ratio: 1.73; 95% CI: 1.15-2.60) and periorbital oedema (hazard ratio: 1.43; 95% CI: 1.03-1.99), with these factors showing high specificity, and the mechanical ventilation variable, showing high sensitivity, with ROC curve of .86. Eyeball exposure, Glasgow score < 6 and periorbital oedema are the risk factors of the risk for corneal injury nursing diagnosis, in critically ill adults. These risk factors guide nursing interventions. This causal validation can improve the risk for corneal injury nursing diagnosis levels of evidence in the NANDA International Taxonomy. It is necessary to guide nursing interventions for critically ill adults with lowered level of consciousness and corneal exposure for the prevention of corneal injury.

Validation and utility of ARDS subphenotypes identified by machine-learning models using clinical data: an observational, multicohort, retrospective analysis

Two acute respiratory distress syndrome (ARDS) subphenotypes (hyperinflammatory and hypoinflammatory) with distinct clinical and biological features and differential treatment responses have been identified using latent class analysis (LCA) in seven individual cohorts. To facilitate bedside identification of subphenotypes, clinical classifier models using readily available clinical variables have been described in four randomised controlled trials. We aimed to assess the performance of these models in observational cohorts of ARDS. In this observational, multicohort, retrospective study, we validated two machine-learning clinical classifier models for assigning ARDS subphenotypes in two observational cohorts of patients with ARDS: Early Assessment of Renal and Lung Injury (EARLI; n=335) and Validating Acute Lung Injury Markers for Diagnosis (VALID; n=452), with LCA-derived subphenotypes as the gold standard. The primary model comprised only vital signs and laboratory variables, and the secondary model comprised all predictors in the primary model, with the addition of ventilatory variables and demographics. Model performance was assessed by calculating the area under the receiver operating characteristic curve (AUC) and calibration plots, and assigning subphenotypes using a probability cutoff value of 0·5 to determine sensitivity, specificity, and accuracy of the assignments. We also assessed the performance of the primary model in EARLI using data automatically extracted from an electronic health record (EHR; EHR-derived EARLI cohort). In Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE; n=2813), a multinational, observational ARDS cohort, we applied a custom classifier model (with fewer variables than the primary model) to determine the prognostic value of the subphenotypes and tested their interaction with the positive end-expiratory pressure (PEEP) strategy, with 90-day mortality as the dependent variable. The primary clinical classifier model had an area under receiver operating characteristic curve (AUC) of 0·92 (95% CI 0·90-0·95) in EARLI and 0·88 (0·84-0·91) in VALID. Performance of the primary model was similar when using exclusively EHR-derived predictors compared with manually curated predictors (AUC=0·88 [95% CI 0·81-0·94] vs 0·92 [0·88-0·97]). In LUNG SAFE, 90-day mortality was higher in patients assigned the hyperinflammatory subphenotype than in those with the hypoinflammatory phenotype (414 [57%] of 725 vs 694 [33%] of 2088; p<0·0001). There was a significant treatment interaction with PEEP strategy and ARDS subphenotype (p=0·041), with lower 90-day mortality in the high PEEP group of patients with the hyperinflammatory subphenotype (hyperinflammatory subphenotype: 169 [54%] of 313 patients in the high PEEP group vs 127 [62%] of 205 patients in the low PEEP group; hypoinflammatory subphenotype: 231 [34%] of 675 patients in the high PEEP group vs 233 [32%] of 734 patients in the low PEEP group). Classifier models using clinical variables alone can accurately assign ARDS subphenotypes in observational cohorts. Application of these models can provide valuable prognostic information and could inform management strategies for personalised treatment, including application of PEEP, once prospectively validated. US National Institutes of Health and European Society of Intensive Care Medicine.

Combined Use of ECMO, Prone Positioning, and APRV in the Management of Severe COVID-19 Patients.

Severe COVID-19-associated Acute Respiratory Distress Syndrome (ARDS) may warrant extracorporeal membrane oxygenation (ECMO). We evaluated the safety and physiologic changes in oxygenation and hemodynamic profile during ECMO, prone positioning, and the two modalities combined in patients receiving veno-venous (VV) ECMO. Cohort study of consecutive adult patients with COVID-19-associated ARDS requiring VV-ECMO, classified into three groups: ECMO support only; Prone positioning only; and Prone positioning during ECMO. We collected hemodynamic, respiratory and ventilation variables as follows: pre-treatment, 1, 6, and 24 h post-treatment, and documented treatment-related complications. On-treatment variables were compared with pre-treatment using one-sample paired t-test with Bonferroni correction. Fourteen patients (mean age 48.1 [SD 9.3] years, male [100%]) received VV-ECMO. Of those, 10 patients had data during prone positioning alone and seven had data while proned on ECMO. While on ECMO, patients had improvement in oxygen saturation, PaO2/FiO2 ratio, and minute ventilation up to 24 h post-treatment. Vasopressor requirements increased with ECMO at 1 h and 24 h post-treatment. Prone positioning was not associated with clinically significant hemodynamic or respiratory changes, either alone or during ECMO support. All patients sustained deep tissue injuries, but only those on the face or chest were related to prone positioning. Three patients required cannula replacement. In-hospital mortality was 43%. VV-ECMO and prone positioning in patients with COVID-19 ARDS was overall well-tolerated; however, physiologic improvements were marginal, and patients sustained deep tissue injuries. Although this was a selected population with high mortality, our data call into question the benefits of these management modalities in this severe COVID-19 population.

Uniformity and energy evaluation of equal cross-section ventilation system(ECVS) for long tunnel in underground buildings

Uniform ventilation is important for the safety of long tunnel in underground buildings, it is difficult to install the large size air duct to ensure the centerline of each cross-section of the traditional variable cross-section ventilation system(VCVS) superimposed on the same horizontal axis, which is significant to the ventilation uniformity, energy consumption and installation convenience of the VCVS. On the contrary, each cross-section of the Equal Cross-section Ventilation System (ECVS) has the same horizontal axis, therefore, it is more convenient to manufacture and install the large size air duct in the underground long tunnel and achieve uniform ventilation. This study proposes an ECVS, using computational fluid dynamics(CFD) numerical simulation analyzed the influences of main duct velocity, aspect ratio, and outlet numbers on uniformity and energy consumption per unit air volume(ECPV). It revealed that when each ventilation equalizer's valve Angle β is given, uniformity of air supply decreases slightly with an increase in the inlet velocity. When the air supply main duct aspect ratio increases, the outlet velocity standard deviation range is from 0.22 to 0.34. When outlet numbers N=7~12 and β are constant, air supply uniformity and resistance coefficient ξ also decrease with the decrease of outlet numbers. The outlet number has a significant influence on the uniformity of system air supply, main duct velocity, and aspect ratio are relatively small. ECPV is positively correlated with the main duct velocity and outlet number, and is negatively correlated with aspect ratio.

The use of capnography for real-time monitoring of mask ventilation during induction of general anaesthesia

The use of capnography for real-time monitoring of mask ventilation during induction of general anaesthesia