FiO2 Research Articles

Evaluation of Nasal Oxygen Administration at Various Flow Rates and Concentrations in Conscious, Standing Adult Horses.

This study evaluated the effects of various flow rates and fractions of oxygen on arterial blood gas parameters and on the fraction of inspired oxygen (FIO2) delivered to the distal trachea. Oxygen was administered to 6 healthy, conscious, standing, adult horses via single nasal cannula positioned within the nasopharynx. Three flow rates (5, 15, 30 L/min) and fractions of oxygen (21, 50, 100%) were delivered for 15 minutes, each in a randomized order. FIO2 was measured at the level of the nares and distal trachea. Adverse reactions were not observed with any flow rate. FIO2 (nares and trachea) and PaO2 increased with increasing flow rate and fraction of oxygen (P < .0001). FIO2 (trachea) was significantly less than FIO2 (nares) at 50% and 100% oxygen at all flow rates (P < .0001). Differences in PaO2 were not observed between 100% oxygen-5L/min and 50% oxygen-15L/min and or between 100% oxygen-15L/min and 50% oxygen-30L/min. Tracheal FIO2 for 100% oxygen-15L/min was increased compared to 50% oxygen-30L/min (P < .0001). Respiratory rate, ETCO2, PaCO2, and pH did not differ between treatments. Administration of 50% oxygen via nasal cannula at 15 and 30 L/min effectively increased in PaO2 and was well tolerated in conscious, standing, healthy horses. While these results can be used guide therapy in hypoxemic horses, evaluation of the administration of 50% oxygen to horses with respiratory disease is warranted.

Single-FiO2 lung modelling with machine learning: a computer simulation incorporating volumetric capnography

We investigated whether machine learning (ML) analysis of ICU monitoring data incorporating volumetric capnography measurements of mean alveolar PCO2 can partition venous admixture (VenAd) into its shunt and low V/Q components without manipulating the inspired oxygen fraction (FiO2). From a 21-compartment ventilation / perfusion (V/Q) model of pulmonary blood flow we generated blood gas and mean alveolar PCO2 data in simulated scenarios with shunt values from 7.3% to 36.5% and a range of FiO2 settings, indirect calorimetry and cardiac output measurements and acid- base and hemoglobin oxygen affinity conditions. A ‘deep learning’ ML application, trained and validated solely on single FiO2 bedside monitoring data from 14,736 scenarios, then recovered shunt values in 500 test scenarios with true shunt values ‘held back’. ML shunt estimates versus true values (n = 500) produced a linear regression model with slope = 0.987, intercept = -0.001 and R2 = 0.999. Kernel density estimate and error plots confirmed close agreement. With corresponding VenAd values calculated from the same bedside data, low V/Q flow can be reported as VenAd—shunt. ML analysis of blood gas, indirect calorimetry, volumetric capnography and cardiac output measurements can quantify pulmonary oxygenation deficits as percentage shunt flow (V/Q = 0) versus percentage low V/Q flow (V/Q > 0). High fidelity reports are possible from analysis of data collected solely at the operating FiO2.

Endothelial Function and Hypoxic–Hyperoxic Preconditioning in Coronary Surgery with a Cardiopulmonary Bypass: Randomized Clinical Trial

A hypoxic-hyperoxic preconditioning (HHP) may be associated with cardioprotection by reducing endothelial damage and a beneficial effect on postoperative outcome in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Patients (n = 120) were randomly assigned to an HHP and a control group. A safe, inhaled oxygen fraction for the hypoxic preconditioning phase (10-14% oxygen for 10 min) was determined by measuring the anaerobic threshold. At the hyperoxic phase, a 75-80% oxygen fraction was used for 30 min. The cumulative frequency of postoperative complications was 14 (23.3%) in the HHP vs. 23 (41.1%), p = 0.041. The nitrate decreased after surgery by up to 20% in the HHP group and up to 38% in the control group. Endothelin-1 and nitric oxide metabolites were stable in HHP but remained low for more than 24 h in the control group. The endothelial damage markers appeared to be predictors of postoperative complications. The HHP with individual parameters based on the anaerobic threshold is a safe procedure, and it can reduce the frequency of postoperative complications. The endothelial damage markers appeared to be predictors of postoperative complications.

Mechanical ventilation with ten versus twenty breaths per minute during cardio-pulmonary resuscitation for out-of-hospital cardiac arrest: A randomised controlled trial

Aim of the studyThis study sought to assess the effects of increasing the ventilatory rate from 10 min−1 to 20 min−1 using a mechanical ventilator during cardio-pulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) on ventilation, acid-base-status, and outcomes. MethodsThis was a randomised, controlled, single-centre trial in adult patients receiving CPR including advanced airway management and mechanical ventilation offered by staff of a prehospital physician response unit (PRU). Ventilation was conducted using a turbine-driven ventilator (volume-controlled ventilation, tidal volume 6 ml per kg of ideal body weight, positive end-expiratory pressure (PEEP) 0 mmHg, inspiratory oxygen fraction (FiO2) 100%), frequency was pre-set at either 10 or 20 breaths per minute according to week of randomisation. If possible, an arterial line was placed and blood gas analysis was performed. ResultsThe study was terminated early due to slow recruitment. 46 patients (23 per group) were included. Patients in the 20 min−1 group received higher expiratory minute volumes [8.8 (6.8–9.9) vs. 4.9 (4.2–5.7) litres, p < 0.001] without higher mean airway pressures [11.6 (9.8–13.6) vs. 9.8 (8.5–12.0) mmHg, p = 0.496] or peak airway pressures [42.5 (36.5–45.9) vs. 41.4 (32.2–51.7) mmHg, p = 0.895]. Rates of ROSC [12 of 23 (52%) vs. 11 of 23 (48%), p = 0.768], median pH [6.83 (6.65–7.05) vs. 6.89 (6.80–6.97), p = 0.913], and median pCO2 [78 (51–105) vs. 86 (73–107) mmHg, p > 0.999] did not differ between groups. Conclusion20 instead of 10 mechanical ventilations during CPR increase ventilation volumes per minute, but do not improve CO2 washout, acidaemia, oxygenation, or rate of ROSC.ClinicalTrials.gov Identifier: NCT04657393.

THE EFFECTIVENESS OF PASSIVE EXERCISES ON ARTERIAL BLOOD GASES IN MECHANICALLY VENTILATED SUBJECTS FROM INTENSIVE CARE UNITS

ABSTRACT. Introduction: Mechanically ventilated critically ill subjects are often given strict bed rest and sometimes completely immobilized because of the severity of their illness and the administration of drugs such as sedatives. Active mobilization is not possible in subjects under deep sedation and unable to follow commands. In this scenario, passive therapy is an interesting alternative. Objective: This study aimed to evaluate the effectiveness of passive exercises on arterial blood gases in mechanically ventilated subjects from intensive care units. Methods: Five mechanically ventilated subjects participated in the study. The subjects were assigned to one study group, which received passive exercises for one daily session, including ten repetitions in three series per articulation. Arterial Blood Gases were assessed by arterial blood sample analysis with the Stat Profile Prime Plus device. Results: The results revealed a marked improvement in arterial blood gas exchange as compared to baseline reflecting an increase in FIO2- the inspiratory fraction of oxygen, pO2- partial pressure of oxygen, and pO2/FIO2- the ratio between the partial pressure of oxygen and the inspiratory fraction of oxygen and a decrease in CO2- carbon dioxide. Conclusions: The passive exercise showed a slight trend of beneficial changes at the cellular level in mechanically ventilated subjects since the first day after admission, which may indicate a reduction in the inspiratory fraction of oxygen and at the end extubation of subjects.

Oxygen and chlorine isotope fractionation during microbial perchlorate reduction in static and flow through systems

Perchlorate (ClO4−) is an oxyanion with both anthropogenic and natural sources that is widespread on earth and throughout the solar system. Stable isotope ratio measurements are a powerful tool to assess the origin and predict the fate of perchlorate in the environment. The aim of this study was to perform an experimental survey of parameters that influence microbial O and Cl isotope fractionation during microbial perchlorate reduction, covering microbiological (genetic background and community context) and environmental (temperature, salinity, electron donor type and limitation) factors. A new method for the purification of perchlorate for isotope ratio mass spectrometry (IRMS) was developed to allow for more efficient sample preparation and suitable for samples containing small amounts of perchlorate (0.4–2 mg). Although most experiments, regardless of treatment, yielded a consistent isotope enrichment factor ratio (Λ = ε18O/ε37Cl ∼ 2.5), a greater variability was observed of individual isotope enrichment factors (ε18O and ε37Cl). Although most experiments yielded isotope enrichment factors (epsilon) in the larger negative range of previously published values, smaller negative values of ε18O and ε37Cl were observed for a halophilic isolate, Haloarcula marismortui, (ε18O = −15 to −22‰ and ε37Cl = −5 to −7‰), and in sediment column experiments (ε18O = −4 to −15‰ and ε37Cl = −1 to −6‰). Given the complexity of isolating individual parameters from our proposed model, we view our dataset as a survey that points to future opportunities where a particular parameter could be isolated to better understand controls on O and Cl isotope fractionation during microbial perchlorate reduction.

Evaluating current guidelines for cardiopulmonary resuscitation using an integrated computational model of the cardiopulmonary system

ObjectiveWe aimed to use a high-fidelity computational model that captures key interactions between the cardiovascular and pulmonary systems to investigate whether current CPR protocols could potentially be improved. MethodsWe developed and validated the computational model against available human data. We used a global optimisation algorithm to find CPR protocol parameters that optimise the outputs associated with return of spontaneous circulation in a cohort of 10 virtual subjects. ResultsCompared with current protocols, myocardial tissue oxygen volume was more than 5 times higher, and cerebral tissue oxygen volume was nearly doubled, during optimised CPR. While the optimal maximal sternal displacement (5.5 cm) and compression ratio (51%) found using our model agreed with the current American Heart Association guidelines, the optimal chest compression rate was lower (67 compressions min−1). Similarly, the optimal ventilation strategy was more conservative than current guidelines, with an optimal minute ventilation of 1500 ml min−1 and inspired fraction of oxygen of 80%. The end compression force was the parameter with the largest impact on CO, followed by PEEP, the compression ratio and the CC rate. ConclusionsOur results indicate that current CPR protocols could potentially be improved. Excessive ventilation could be detrimental to organ oxygenation during CPR, due to the negative haemodynamic effect of increased pulmonary vascular resistance. Particular attention should be given to the chest compression force to achieve satisfactory CO. Future clinical trials aimed at developing improved CPR protocols should explicitly consider interactions between chest compression and ventilation parameters.

Effects of Adiabatic Flame Temperature and Oxygen Concentration in CH4/N2/O2 Nonswirl Jet Flames: Experimental and Numerical Study

AbstractThe combustion characteristics of oxygen-enriched air–methane (i.e., O2/N2/CH4) flames in a premixed mode are investigated using both experimentally and numerically under atmospheric conditions for emissions reduction purposes. The investigation is carried out using a gas turbine model combustor equipped with a multihole burner that mimics gas turbine micromixer burners. The resulting flame is of jet type, and the velocity of the jet is kept at 5.2 m/s for all the considered flames. Models used in the numerical study include large eddy simulation, discrete ordinate, and partially premixed combustion for turbulence, radiation, and species models, respectively. The numerical results are validated, and a suitable agreement is achieved with experimental data. The results indicated that the temperature distribution, shape, and size of O2/N2/CH4 flames are predominantly controlled by adiabatic flame temperature (Tad). However, the oxygen fraction, rather than Tad, is responsible for the reaction progress. The emission of NO, CO, and CO2 increases with an increase in oxygen fraction, and the product formation in O2/N2/CH4 flames is less compared to their oxy-fuel (i.e., O2/CO2/CH4) counterparts, because N2 is mostly inert, compared to CO2. The latter participates significantly in flame reactions, which increases the rate of product formation in O2/CO2/CH4 flames.

Development of titanium-based certified reference materials

The Institute for Certified Reference Materials (ICRM) issued for the first time certified reference materials (CRM 11777-2021) of the mass fraction of hydrogen, oxygen and nitrogen in titanium-based materials, i.e., titanium alloy 2V (ISO 1-1) and titanium VT 1-00 (ISO 1-2). The finished material is presented in the form of cylinders 2.5 mm in diameter and 5-6 mm height. The mass of a cylinder is about 0.1 g. To certify gas-forming elements, we used the methods of fusion under inert gas flow (hydrogen, oxygen, nitrogen) and high-temperature vacuum extraction with mass spectroscopy (hydrogen). The analyzers were calibrated using CRM, a gas dose (for hydrogen), and a substance of constant stoichiometric composition (potassium nitrate). Conditions for the determination of the mass fraction of hydrogen, oxygen, and nitrogen in titanium and titanium alloys using an ELTRA ONH-2000 gas analyzer in solid materials have been refined in the analytical laboratory ICRM. The accuracy indicators (assigned characteristics) of the measurement procedure were determined using a great bulk of experimental data.

Pharmacokinetics and pharmacodynamics of imatinib for optimal drug repurposing from cancer to COVID-19

IntroductionIn the randomized double-blind placebo-controlled CounterCOVID study, oral imatinib treatment conferred a positive clinical outcome and a signal for reduced mortality in COVID-19 patients. High concentrations of alpha-1 acid glycoprotein (AAG) were observed in these patients and were associated with increased total imatinib concentrations. AimsThis post-hoc study aimed to compare the difference in exposure following oral imatinib administration in COVID-19 patients to cancer patients and assess assocations between pharmacokinetic (PK) parameters and pharmacodynamic (PD) outcomes of imatinib in COVID-19 patients. We hypothesize that a relatively higher drug exposure of imatinib in severe COVID-19 patients leads to improved pharmacodynamic outcome parameters. Methods648 total concentration plasma samples obtained from 168 COVID-19 patients were compared to 475 samples of 105 cancer patients, using an AAG-binding model. Total trough concentration at steady state (Cttrough) and total average area under the concentration-time curve (AUCtave) were associated with ratio between partial oxygen pressure and fraction of inspired oxygen (P/F), WHO ordinal scale (WHO-score) and liberation of oxygen supplementation (O2lib). Linear regression, linear mixed effects models and time-to-event analysis were adjusted for possible confounders. ResultsAUCtave and Cttrough were respectively 2.21-fold (95%CI 2.07–2.37) and 1.53-fold (95%CI 1.44–1.63) lower for cancer compared to COVID-19 patients. Cttrough, not AUCtave, associated significantly with P/F (β=-19,64; p-value=0.014) and O2lib (HR 0.78; p-value= 0.032), after adjusting for sex, age, neutrophil-lymphocyte ratio, dexamethasone concomitant treatment, AAG and baseline P/F-and WHO-score. Cttrough, but not AUCtave associated significantly with WHO-score. These results suggest an inverse relationship between PK-parameters, Cttrough and AUCtave, and PD outcomes. ConclusionCOVID-19 patients exhibit higher total imatinib exposure compared to cancer patients, attributed to differences in plasma protein concentrations. Higher imatinib exposure in COVID-19 patients did not associate with improved clinical outcomes. Cttrough and AUCtave inversely associated with some PD-outcomes, which may be biased by disease course, variability in metabolic rate and protein binding. Therefore, additional PKPD analyses into unbound imatinib and its main metabolite may better explain exposure-response.

Optimal positive end-expiratory pressure obtained with titration of a fraction of inspiratory oxygen: a randomized controlled clinical trial.

Optimal intraoperative positive end-expiratory pressure (PEEP) improves patient outcomes. Pulse oximetry has been used to determine the lung opening and closing pressures. Therefore, we hypothesized that intraoperative optimal PEEP obtained by titrating inspiratory oxygen fraction (FiO2) guided with pulse oximetry could improve perioperative oxygenation. Forty-six males undergoing elective robotic-assisted laparoscopic prostatectomy were randomly assigned to either the optimal PEEP group (group O; n=23) or the fixed PEEP of 5 cmH2O group (group C; n=23). Optimal PEEP, defined as the PEEP with the lowest FiO2 or 0.21 to maintain SpO2 greater than or equal to 95%, was obtained in both groups after placing the patients in the Trendelenburg position and conducting intraperitoneal insufflation. Optimal PEEP was maintained for patients in group O. A PEEP of 5 cmH2O intraoperatively was maintained for patients in group C. Both groups were extubated in a semisitting position once the extubation criteria were met. The primary outcome was the arterial oxygen partial pressure (PaO2) divided by the inspiratory oxygen fraction (FiO2) prior to extubation. The secondary outcome was the incidence of postoperative hypoxemia (SpO2 less than 92% on room air after extubation) in the postanesthesia care unit (PACU). The median optimal PEEP was 16 cmH2O (IQR 12-18). The PaO2/FiO2 prior to extubation was significantly higher in group O than in group C (77.0±4.9 kPa vs. 60.6±5.9 kPa; P=0.04). PaO2/FiO2 was also significantly higher in group O 30 minutes after extubation (57.6±1.9 vs. 46.6±1.8 kPa; P=0.01). The incidence of hypoxemia on room air in the PACU was significantly lower in group O than in group C (4.3% vs. 30.4%; P=0.02). Intraoperative optimal PEEP can be achieved by a titration of FiO2 guided with SpO2. Maintaining intraoperative optimal PEEP improves intraoperative oxygenation and reduces the incidence of postoperative hypoxemia. The study was prospectively registered on September 10, 2021, in the Chinese Clinical Trial Registry (identifier: ChiCTR2100051010).

Cánula nasal de alto flujo en pacientes críticos: una revisión narrativa

High-flow nasal cannula has become one of the main strategies for non-invasive ventilatory support in hypoxemic acute respiratory failure, mainly after the COVID-19 pandemic. However, its use extends beyond this scenario and covers different clinical conditions such as the post-extubation period, post-surgical period, hypercapnic respiratory failure and life support in immunosuppressed, trasplant or cancer patients. Manuscripts that support its application have been widely disseminated and the degree of evidence is high enough to recommend its use. Therefore, it is necessary to highlight its physiological effects such as comfort, precise fraction of inspiratory oxygen, CO2 lavage or optimize end-expiratory lung volume to understand its mechanism of action and improve patients’ outcomes. The objective of this narrative review is to offer a brief and concise summary of the benefits of applying this therapy in different clinical scenarios without the rigid structure of a systematic review. Based on these lines, the curious reader can expand the scientific evidence that supports the use of the high-flow nasal cannula in each particular scenario.

L'ossigenoterapia

Oxygen supplementation represents a fundamental therapy in several clinical conditions, both acute and chronic. Starting from some concepts of respiratory physiopathology, this paper discusses the approach to a child with respiratory distress and respiratory failure, focuses on the main signs and symptoms of hypoxia, hypercapnia and increased work of breathing and explains the methods to assess the severity of the clinical status, highlighting the relevance of the SpO2/FiO2 ratio (peripheral oxygen saturation/inspiratory oxygen fraction). Furthermore, this work aims to summarize the main methods of oxygen delivery, their relative indications, by underlining advantages and possible complications such as blow-by oxygen, low flow nasal cannula and face mask (simple, Venturi, rebreathing and non-rebreathing). The focus is on two new oxygen delivery devices, High Flow Nasal Cannula (HFNC) and Continuous Positive Airway Pressure (CPAP), which in recent years have more and more been used not only in emergency units but also in paediatric wards.

Flow channel structure optimization and analysis of proton exchange membrane fuel cell based on the finite data mapping and multi-field synergy principle

Design and optimization of the flow channel structure is an effective approach to improve the performance of the proton exchange membrane fuel cell (PEMFC). Based on the three-dimensional mathematical model of a single cell, this paper applied the artificial neural network method to obtain the exact relationship between the flow channel geometry size and the output performance of PEMFC with finite data by combining response surface analysis and central composite design. Under the Based on this model, the optimal double-inverted trapezoidal tapering channel structure and related dimensional parameters are obtained by NSGA-II algorithm. The comparisons show that the optimized PEMFC improves the peak power by 8.5% and extends the operating range of current density by 15.5%. Multi-field synergy principle analysis revealed a 5.95% increase in overall heat transfer capability, enhanced mass transfer capability on the cathode side, and a 28.57% increase in the average mass fraction of oxygen at the diffusion layer and runner crossover. In addition, the total drainage capacity was increased by 5.35%. In conclusion, the proposed finite data mapping optimization method and multi-field synergistic theoretical analysis can effectively guide and evaluate the design and optimization of the PEMFC.

EARLY INITIATION OF RENAL REPLACEMENT THERAPY IN INTENSIVE CARE UNIT PATIENTS WITH BOTH ACUTE RESPIRATORY DISTRESS SYNDROME AND SEPSIS WITH OR WITHOUT RENAL FAILURE: A RETROSPECTIVE COHORT STUDY BASED ON PROPENSITY SCORE MATCHING.

Background: It is unknown whether early renal replacement therapy (RRT) initiation strategy in intensive care unit (ICU) patients with both acute respiratory distress syndrome (ARDS) and sepsis with or without renal failure is clinically beneficial. Patients and methods: A total of 818 patients with both ARDS and sepsis admitted to the ICU of Tianjin Medical University General Hospital were included in the analysis. Early RRT was defined as initiating the RRT strategy within 24 h of admission. The relationship between early RRT and clinical outcomes, including primary (30-day mortality) and secondary (90-day mortality, serum creatinine, Pa o2 /Fi o2 , duration of invasive mechanical ventilation, cumulative fluid output, and cumulative fluid balance) outcomes, was compared using propensity score matching (PSM). Results: A total of 277 patients (33.9% of the total population) underwent an early RRT initiation strategy before PSM. After PSM, a cohort of 147 patients with early RRT and 147 patients without early RRT with matched baseline characteristics (including serum creatinine at admission) were constructed. Early RRT was not significantly associated with 30- (hazard ratio [HR], 1.25; 95% confidence interval [CI], 0.85-1.85; P = 0.258) or 90-day mortality (HR, 1.30; 95% CI, 0.91-1.87, P = 0.150). At each time point within 72 h after admission, there was no significant difference in serum creatinine, Pa o2 /Fi o2 and duration of mechanical ventilation between the early and the no early RRT groups. Early RRT significantly increased total output at all time points within 72 h of admission and reached a statistically significant negative fluid balance at 48 h. Conclusions: Early RRT initiation strategies had no statistically significant survival benefit in ICU patients with both ARDS and sepsis, with or without renal failure, nor did they significantly improve serum creatinine and oxygenation or shorten the duration of mechanical ventilation. The use and timing of RRT in such patients should be thoroughly investigated.

Oxygenation thresholds for invasive ventilation in hypoxemic respiratory failure: a target trial emulation in two cohorts

BackgroundThe optimal thresholds for the initiation of invasive ventilation in patients with hypoxemic respiratory failure are unknown. Using the saturation-to-inspired oxygen ratio (SF), we compared lower versus higher hypoxemia severity thresholds for initiating invasive ventilation.MethodsThis target trial emulation included patients from the Medical Information Mart for Intensive Care (MIMIC-IV, 2008–2019) and the Amsterdam University Medical Centers (AmsterdamUMCdb, 2003–2016) databases admitted to intensive care and receiving inspired oxygen fraction ≥ 0.4 via non-rebreather mask, noninvasive ventilation, or high-flow nasal cannula. We compared the effect of using invasive ventilation initiation thresholds of SF < 110, < 98, and < 88 on 28-day mortality. MIMIC-IV was used for the primary analysis and AmsterdamUMCdb for the secondary analysis. We obtained posterior means and 95% credible intervals (CrI) with nonparametric Bayesian G-computation.ResultsWe studied 3,357 patients in the primary analysis. For invasive ventilation initiation thresholds SF < 110, SF < 98, and SF < 88, the predicted 28-day probabilities of invasive ventilation were 72%, 47%, and 19%. Predicted 28-day mortality was lowest with threshold SF < 110 (22.2%, CrI 19.2 to 25.0), compared to SF < 98 (absolute risk increase 1.6%, CrI 0.6 to 2.6) or SF < 88 (absolute risk increase 3.5%, CrI 1.4 to 5.4). In the secondary analysis (1,279 patients), the predicted 28-day probability of invasive ventilation was 50% for initiation threshold SF < 110, 28% for SF < 98, and 19% for SF < 88. In contrast with the primary analysis, predicted mortality was highest with threshold SF < 110 (14.6%, CrI 7.7 to 22.3), compared to SF < 98 (absolute risk decrease 0.5%, CrI 0.0 to 0.9) or SF < 88 (absolute risk decrease 1.9%, CrI 0.9 to 2.8).ConclusionInitiating invasive ventilation at lower hypoxemia severity will increase the rate of invasive ventilation, but this can either increase or decrease the expected mortality, with the direction of effect likely depending on baseline mortality risk and clinical context.

Effect of ultrasound-guided lung recruitment manoeuvre on perioperative atelectasis during laparoscopy in young infants: A randomised controlled trial

BackgroundPneumoperitoneum is a risk factor for perioperative atelectasis in infants. This research aimed to investigate whether lung recruitment manoeuvres guided by ultrasound are more effective for young infants (<3 months) during laparoscopy under general anaesthesia. MethodsYoung infants (<3 months) undergoing general anaesthesia during laparoscopic surgery (>2 h) were randomised to either conventional lung recruitment (control group) or ultrasound-guided lung recruitment (ultrasound group) once per hour. Mechanical ventilation was started with a tidal volume of 8 mL·kg−1, positive end-expiratory pressure of 6 cm H2O and 40% inspired oxygen fraction. Lung ultrasound (LUS) was performed four times (T1 was performed 5 min after intubation and before pneumoperitoneum set, T2 was performed after pneumoperitoneum, T3 was performed 1 min after surgery, and T4 was performed before being discharged from post-anaesthesia care unit [PACU]) in each infant. The primary outcome was the incidence of significant atelectasis at T3 and T4 (defined by LUS consolidation score ≥ 2 in any region). Results62 babies were enrolled in the experiment and 60 infants were included in the analysis. Before the recruitment, atelectasis was similar between infants randomised to the control or ultrasound group at T1 (83.3% vs 80.0%; P = 0.500) and T2 (83,3% vs 76.7%; P = 0.519). The incidence of atelectasis at T3 and T4 were lower in the ultrasound group (26.7% and 33.3%), compared with infants randomised to conventional lung recruitment (66.7% and 70%) (P = 0.002; P = 0.004; respectively). ConclusionsUltrasound-guided alveolar recruitment reduced the perioperative incidence of atelectasis in infants <3 months during laparoscopy under general anaesthesia.

Preparation of powder by electrical discharge erosion and sintering of ultrafine WC-5TiC-10Co alloy with high hardness

In this work, studies were carried out on obtaining a powder by electrical discharge erosion (EDE) of a WC-5TiC-10Co cemented carbide, sintering an ultrafine-grained alloy from the obtained powder, and studying the microstructures and properties of the obtained particles and alloys. We have established that with an increase in the pulse energy from 0.5 J to 10 J, the EDE productivity increases linearly. At the same time, energy consumption decreases and tends towards a constant value (3.4–4.2 kWt*h/kg). It has been established that an undesirable change in the carbon content in the resulting powder from the liquid pyrolysis is proportional to the product of the specific energy consumption and the difference in the mole fractions of carbon and oxygen in the liquid. Excess carbon was removed by heat treatment in the appropriate volume of CO2. It has been established that EDE results in a complete dissolution of tungsten in cubic carbide (Ti,W)C, which is retained in the formed particles. During further heat treatment and sintering, new plate-like ultrafine WC grains grow from a supersaturated (Ti,W)C solution. An increased concentration of tungsten is retained during sintering in ultrafine-grained grains of a supersaturated (Ti,W)C solid solution. By reducing the average diameter of the WC grains from 1.45 μm to 0.42 μm and increasing the carbide content (Ti,W)C, the hardness of the obtained alloys increases from 1410 HV in the original alloy to 1650 HV in the sintered alloy. Fracture toughness increases due to formation of lamellar WC grains from 12.9 mPa*m1/2 to 14.1 MPa*m1/2.

Ventilatory response and stability of oxygen saturation during a hypoxic challenge in very preterm infants.

Preterm infants have immature control of breathing and impaired pulmonary gas exchange. We hypothesized that infants with bronchopulmonary dysplasia (BPD) have a blunted ventilatory response and peripheral oxygen saturation (SpO2 ) instability during a hypoxic challenge. We evaluated the response to hypoxia in 57 very preterm infants (38 no BPD, 10 mild BPD, 9 moderate-to-severe BPD) at 36 weeks' postmenstrual age. The fraction of inspired oxygen (FI O2 ) was reduced stepwise at 5-min intervals to achieve peripheral SpO2 between 86% and 95%. The lowest permissible FI O2 and SpO2 were 0.14% and 86%. We recorded SpO2 , FI O2 , and the respiratory signal (respiratory inductive plethysmography). We calculated respiratory rate (RR), tidal volume (VT ), minute ventilation (VE ), and respiratory drive (ratio between VT and inspiratory time, VT /TI ). SpO2 variability was expressed as the interquartile range (IQR). FI O2 was reduced from a median (Q1, Q3) of 0.21 (0.21, 0.21) to 0.17 (0.17, 0.18). We observed a marked individual variability in the ventilatory response to the hypoxic challenge, regardless of BPD severity. At the lowest permissible FI O2 , 37(65%) infants reduced their VE , and 20 (35%) increased minute ventilation; 20infants (35%) developed periodic breathing associated with increased SpO2 IQR and lower SpO2 minima, and 16 (28%) exhibited an oscillatory pattern in VE and SpO2 without end-expiratory pauses, regardless of BPD severity. In very preterm infants, a mild hypoxic challenge reduced ventilation, increased SpO2 variability and periodic breathing regardless of BPD severity.

Efficacy and safety of high-flow nasal cannula therapy in elderly patients with acute respiratory failure

IntroductionTo assess the efficacy and safety of high-flow nasal cannula (HFNC) in elderly patients with acute respiratory failure (ARF) not due to COVID-19, refractory to treatment with conventional oxygen therapy and/or intolerant to noninvasive ventilation (NIV) or continuous positive airway pressure (CPAP) and without criteria for admission to intensive care units (ICU). MethodsProspective observational study of patients with ARF treated with HFNC who presented clinical and arterial blood gas deterioration after 24 h of medical treatment and oxygenation by conventional systems. The degree of dyspnoea, gas exchange parameters (arterial O2 pressure/inspired O2 fraction ratio (PaO2/FiO2); oxygen saturation measured by oximetry/ inspired fraction of oxygen (Sp02/Fi02), ROX index), degree of patient tolerance and mortality were evaluated. These were measured at discharge from the emergency department (ED), 24 h after treatment with conventional oxygenation and 60, 120 min and 24 h after initiation of HFNC. The results were analyzed for all patients as a whole and for patients with hypercapnia (arterial carbon dioxide tension (PaCO2) < 45 mmHg) separately. Results200 patients were included in the study between November 2019 and November 2020, with a mean age of 83 years, predominantly women (61.9%), obese (Body Mass Index (BMI) 31.1), with high comorbidity (Charlson index 4) and mild-moderate degree of dependence (Barthel 60). A number of 128 patients (64%) were hypercapnic. None had respiratory acidosis (pH 7.39). Evaluation at 60 min, 120 min and 24 h showed significant improvement in all patients and in the subgroup of hypercapnic patients with respect to baseline parameters in respiratory rate (RR), dyspnoea, ROX index, PaO2/FiO2, SpO2/FiO2 and patient comfort. No changes in PaCO2 or level of consciousness were observed. HFNC was well tolerated. Ten patients (5%) died due to progression of the disease causing ARF. ConclusionsHFNC is an effective and safe alternative in elderly patients with ARF not due to COVID-19, refractory to treatment with conventional oxygen therapy and/or intolerant to NIV or CPAP and without criteria for admission to ICU.