Exhaled Carbon Dioxide Research Articles

Preventing unrecognised oesophageal intubation.

Major harm from unrecognised oesophageal intubation continues, despite the 2018 Royal College of Anaesthetists' 'no trace, wrong place' campaign. It is likely that publicly reported cases represent a fraction of real occurrences. This article summarises a 2022 consensus guideline on the prevention of unrecognised oesophageal intubation from the Project for Universal Management of Airway and international airway societies. The guideline is written for all airway operators and assistants, in any clinical setting, and readers are advised to deepen their understanding by studying the original guideline. The recommendations include how to avoid and recognise oesophageal intubation as well as a set of logical actions to take when it is a plausible possibility, even if it is not suspected. The guideline emphasises the importance of videolaryngoscopy, capnography and oxygen saturation monitoring for all tracheal intubations, wherever performed. It introduces the concept of sustained exhaled carbon dioxide, which is central to identifying oesophageal intubation, and acting to prevent progression to unrecognised oesophageal intubation. In the absence of sustained exhaled carbon dioxide, the default action is to remove the tube. This will mean some tracheal placed tubes are removed but based on a risk-benefit analysis, this is desirable. The tube should only be left in place if there is clear danger in removing it and in this event, its position should be confirmed, using repeat videolaryngoscopy plus one other of bronchoscopy, skilled ultrasound or use of an oesophageal detector device. The importance of human factors is underlined; for instance, the value of a shared and vocalised report of videolaryngoscopy view and trained assistants working with the operator to confirm whether the criteria for sustained exhaled carbon dioxide are met, to minimise error and improve team working.

Effective Following: A Counterpart to Leadership

Effective Following: A Counterpart to Leadership

Effect of Omega-3 Polyunsaturated Fatty Acids Intake on Eosinophil Airway Inflammation in University Athletes.

Though athletes have a high risk of respiratory disorders, effective prevention has not yet to be identified. Omega-3 (n-3) polyunsaturated fatty acids (PUFA) have some practical anti-inflammatory effects in allergy, and therefore may reduce airway inflammation in athletes. This study aimed to assess whether n-3 PUFA intake affects airway inflammation in university athletes. Twenty-three males were divided into three groups: 1) the eosinophilic airway inflammation group (I_PUFA group; fractional exhaled nitric oxide (FeNO ≥ 25 ppb, n = 10); 2) the non-eosinophilic airway inflammation group (N_PUFA group; FeNO < 25 ppb, exhaled carbon dioxide (eCO) ≥ 3.6 ppm, n = 5); and 3) the control group (FeNO < 25 ppb, eCO < 3.6 ppm, n = 8). Participants took supplements containing 260 mg of docosapentaenoic acid and 600 mg of eicosapentaenoic acid (EPA) daily for 3 weeks. Baseline measurements of FeNO, respiratory impedance, respiratory function, dietary intake (food frequency questionnaires), and blood tests were performed. FeNO and respiratory impedance were measured weekly, and the rest were measured after 3 weeks. There was a significant decrease in FeNO levels from baseline at 2 and 3 weeks in the I_PUFA group (54.7 ± 8.5 ppb vs. 45.1 ± 9.1 and 45.4 ± 7.7 ppb; mean ± standard error (SE), P < 0.05). After 3 weeks, FeNO levels remained unchanged in the N_PUFA and control groups, and respiratory impedance and function remained unchanged in all groups. Blood EPA levels significantly increased in the I_PUFA and N_PUFA groups (I_PUFA, 27.7 ± 16.9 vs. 52.1 ± 12.3 µg/mL; N_PUFA, 20.8 ± 8.7 vs. 70.4 ± 36.1 µg/mL; mean ± standard deviation (SD), P < 0.05). No changes were observed in dietary intake over the 3 weeks. n-3 PUFA supplementation for 3 weeks reduced airway inflammation in athletes with FeNO levels ≥ 25 ppb.

Analgesic efficacy of ultrasound-guided transversus abdominis plane block in dogs undergoing ovariectomy.

In medicine, the transversus abdominis plane (TAP) block has been shown as an effective method of analgesia in several surgical procedures. In this context, this prospective, randomized, blinded study aimed to evaluate the analgesic efficacy of TAP block, guided by ultrasound in female dogs submitted to ovariectomy. Therefore, 32 animals randomly assigned in two groups (n = 16) were used. Groups consisted of TAP block control (TBC) which received water injection (0.2 ml kg-1 point), and TAP block bupivacaine (TBB) which received bupivacaine (0.2 ml kg-1 point at 0.25%); both groups were submitted to four-point approach. Animals were pre-medicated with acepromazine (0.03 mg kg-1) and meperidine (2 mg kg-1) IM, propofol was used as anesthetic induction (3-5 mg kg-1) IV, and isoflurane was used to maintain. To standardize groups, the animals received a continuous infusion of remifentanil (0.2μg kg-1 min) and rocuronium (0.6 mg kg-1) IV in the intraoperative period. Variables measured were the heart and respiratory rates, blood pressure, temperature, peripheral oxyhemoglobin saturation, exhaled carbon dioxide concentration, exhaled isoflurane concentration, serum cortisol, analgesia, and sedation. Before the pre-anesthetic medication (Baseline) and 1, 2, 4, 6, and 8 h after extubation, pain and sedation were assessed using a numeric rating scale (NRS), Glasgow composite measure pain scale (GCMPS-SF), and sedation scale. Moreover, serum cortisol was measured at different moments. The results show that in the intraoperative period, there was no significant difference between groups. After surgery, in TBC, 13 out of 16 animals required analgesic rescue, whereas, in TBB, this occurred only in one animal. Regarding the measurement of serum cortisol, the TBC group showed a significant difference when compared to the baseline time in the traction of the first ovary (p < 0.0001), 2 h (p = 0.0441), and 8 h (p = 0.0384) after extubation. In TBB, cortisol showed a significant increase only in the traction of the first ovary and 2 h after extubation (p < 0.0001). The technique using ultrasound-guided TAP block in two points approach by hemiabdomen with 0.2 ml kg-1 bupivacaine 0.25% was effective in providing post-operative analgesia in dogs undergoing ovariectomy.

Euglena, a Gravitactic Flagellate of Multiple Usages.

Human exploration of space and other celestial bodies bears a multitude of challenges. The Earth-bound supply of material and food is restricted, and in situ resource utilisation (ISRU) is a prerequisite. Excellent candidates for delivering several services are unicellular algae, such as the space-approved flagellate Euglena gracilis. This review summarizes the main characteristics of this unicellular organism. Euglena has been exposed on various platforms that alter the impact of gravity to analyse its corresponding gravity-dependent physiological and molecular genetic responses. The sensory transduction chain of gravitaxis in E. gracilis has been identified. The molecular gravi-(mechano-)receptors are mechanosensory calcium channels (TRP channels). The inward gated calcium binds specifically to one of several calmodulins (CaM.2), which, in turn, activates an adenylyl cyclase. This enzyme uses ATP to produce cAMP, which induces protein kinase A, followed by the phosphorylation of a motor protein in the flagellum, initiating a course correction, and, finally, resulting in gravitaxis. During long space missions, a considerable amount of food, oxygen, and water has to be carried, and the exhaled carbon dioxide has to be removed. In this context, E. gracilis is an excellent candidate for biological life support systems, since it produces oxygen by photosynthesis, takes up carbon dioxide, and is even edible. Various species and mutants of Euglena are utilized as a producer of commercial food items, as well as a source of medicines, as it produces a number of vitamins, contains numerous trace elements, and synthesizes dietary proteins, lipids, and the reserve molecule paramylon. Euglena has anti-inflammatory, -oxidant, and -obesity properties.

Intrapulmonary shunt and alveolar dead space in a cohort of patients with acute COVID-19 pneumonitis and early recovery.

Pathological evidence suggests that coronavirus disease 2019 (COVID-19) pulmonary infection involves both alveolar damage (causing shunt) and diffuse microvascular thrombus formation (causing alveolar dead space). We propose that measuring respiratory gas exchange enables detection and quantification of these abnormalities. We aimed to measure shunt and alveolar dead space in moderate COVID-19 during acute illness and recovery. We studied 30 patients (22 males; mean±sd age 49.9±13.5 years) 3-15 days from symptom onset and again during recovery, 55±10 days later (n=17). Arterial blood (breathing ambient air) was collected while exhaled oxygen and carbon dioxide concentrations were measured, yielding alveolar-arterial differences for each gas (P A-aO2 and P a-ACO2 , respectively) from which shunt and alveolar dead space were computed. For acute COVID-19 patients, group mean (range) for P A-aO2 was 41.4 (-3.5-69.3) mmHg and for P a-ACO2 was 6.0 (-2.3-13.4) mmHg. Both shunt (% cardiac output) at 10.4% (0-22.0%) and alveolar dead space (% tidal volume) at 14.9% (0-32.3%) were elevated (normal: <5% and <10%, respectively), but not correlated (p=0.27). At recovery, shunt was 2.4% (0-6.1%) and alveolar dead space was 8.5% (0-22.4%) (both p<0.05 versus acute). Shunt was marginally elevated for two patients; however, five patients (30%) had elevated alveolar dead space. We speculate impaired pulmonary gas exchange in early COVID-19 pneumonitis arises from two concurrent, independent and variable processes (alveolar filling and pulmonary vascular obstruction). For most patients these resolve within weeks; however, high alveolar dead space in ∼30% of recovered patients suggests persistent pulmonary vascular pathology.

Preventing unrecognised oesophageal intubation: a consensus guideline from the Project for Universal Management of Airways and international airway societies.

Across multiple disciplines undertaking airway management globally, preventable episodes of unrecognised oesophageal intubation result in profound hypoxaemia, brain injury and death. These events occur in the hands of both inexperienced and experienced practitioners. Current evidence shows that unrecognised oesophageal intubation occurs sufficiently frequently to be a major concern and to merit a co-ordinated approach to address it. Harm from unrecognised oesophageal intubation is avoidable through reducing the rate of oesophageal intubation, combined with prompt detection and immediate action when it occurs. The detection of 'sustained exhaled carbon dioxide' using waveform capnography is the mainstay for excluding oesophageal placement of an intended tracheal tube. Tube removal should be the default response when sustained exhaled carbon dioxide cannot be detected. If default tube removal is considered dangerous, urgent exclusion of oesophageal intubation using valid alternative techniques is indicated, in parallel with evaluation of other causes of inability to detect carbon dioxide. The tube should be removed if timely restoration of sustained exhaled carbon dioxide cannot be achieved. In addition to technical interventions, strategies are required to address cognitive biases and the deterioration of individual and team performance in stressful situations, to which all practitioners are vulnerable. These guidelines provide recommendations for preventing unrecognised oesophageal intubation that are relevant to all airway practitioners independent of geography, clinical location, discipline or patient type.

A Study of NT-ProBNP and ETCO2 in Patients Presenting with Acute Dyspnoea

Objectives: In patients presenting with acute dyspnoea in the emergency department (ED), the early and correct diagnosis may present a significant clinical challenge. The most common diagnoses of acute shortness of breath and manifesting signs of respiratory distress are decompensated heart failure (HF), pneumonia, chronic obstructive pulmonary disease (COPD), pulmonary embolism (PE), asthma, and acute respiratory distress syndrome (ARDS) and other causes like anaemia. The aim of the study was to measure NT-pro brain natriuretic peptide (BNP) and exhaled end-tidal carbon dioxide (ETCO2) in patients presenting with dyspnoea. Material and Methods: This prospective, cross-sectional and observational study was performed at the Government Medical College and Hospital, Nagpur, between October 2019 and October 2021 in patients admitted to the medicine intensive care unit. Three groups of patients were compared: (1) HF-related acute dyspnoea group (n = 52), (2) pulmonary (COPD/PE)-related acute dyspnoea group (n = 31) and (3) sepsis with ARDS-related dyspnoea group (n = 13). All patients underwent initial clinical examination with a recording of initial vital parameters along with on-admission ETCO2 measurement, NT-proBNP testing, arterial blood gas testing, lung ultrasound examination, 2D echocardiography, chest X-rays, and other basic diagnostic laboratory testing. Results: We included 96 patients during the study period. Median NT-proBNP was found to be maximum for the HF group (11,480 pg/ml) followed by the sepsis group (780 pg/ml) and pulmonary group (231 pg/ml). The mean ETCO2 value was found to be maximum in the pulmonary group (48.610 mmHg) followed by HF (31.51 mmHg) and the sepsis group (19.46 mmHg). All results were found to be statistically significant (P &lt; 0.05). Conclusion: NT-proBNP has high diagnostic accuracy in differentiating acute HF-related dyspnoea from pulmonary (COPD and ARDS)-related acute dyspnoea. The higher levels of ETCO2 help in diagnosing patients with COPD.

Prediction of exhaled carbon dioxide concentration using a computer-simulated person that included alveolar gas exchange.

Accurate prediction of inhaled CO2 concentration and alveolar gas exchange efficiency would improve the prediction of CO2 concentrations around the human body, which is essential for advanced ventilation design in buildings. We therefore, developed a computer-simulated person (CSP) that included a computational fluid dynamics approach. The CSP simulates metabolic heat production at the skin surface and carbon dioxide (CO2 ) gas exchange at the alveoli during the transient breathing cycle. This makes it possible to predict the CO2 distribution around the human body. The numerical model of the CO2 gas exchange mechanism includes both the upper and lower airways and makes it possible to calculate the alveolar CO2 partial pressure; this improves the prediction accuracy. We used the CSP to predict emission rates of metabolically generated CO2 exhaled by a person and assumed that the tidal volume will be unconsciously reduced as a result of exposure to poor indoor air quality. A reduction in tidal volume resulted in a decrease in CO2 emission rates of the same magnitude as was observed in our published experimental data. We also observed that the predicted inhaled CO2 concentration depended on the flow pattern around the human body, as would be expected.

The physiological, perceptual, and thermoregulatory responses to facemask use during exercise.

The use of masks in public settings and when around people has been recommended to limit the spread of Coronavirus disease 2019 (COVID-19) by major public health agencies. Several different types of masks classified as either medical- or non-medical grade are commonly used among the public. However, concerns with difficulty breathing, re-breathing exhaled carbon dioxide, a decrease in arterial oxygen saturation, and a decrease in exercise performance have been raised regarding the use of mask during exercise. We review the current knowledge related to the effect of different masks during exercise on cardiorespiratory, metabolic, thermoregulatory, and perceptual responses. As such, the current literature seems to suggest that there are minimal changes to cardiovascular, metabolic, and no changes to thermoregulatory parameters with facemask use. However, differences in ventilatory parameters have been reported with submaximal and maximal intensity exercise to volitional fatigue. Literature on perceptual responses to exercise indicate an impact on ratings of perceived exertion, dyspnea, and overall discomfort dependent on mask use as well as exercise intensity. In conclusion, data from the current literature suggests a minimal impact on physiological, perceptual, and thermoregulatory responses dependent on the type of mask used during exercise.

Evaluation of Iron-Based Metal–Organic Framework Activation Temperatures in Acetylene Adsorption

One of the major issues regarding long-term human space exploration is the need for a breathable atmosphere. A major component toward achieving this goal is both the removal of exhaled carbon dioxide (CO2) and the generation or recovery of oxygen (O2). NASA's current technology only operates at about 50% efficiency due to the need to vent the methane that is produced during the CO2 reduction process. One method of improving the efficiency of this process is through plasma pyrolysis, wherein the methane is pyrolyzed to produce hydrogen and various dehydrogenated carbon byproducts. In this process, acetylene is one of the main components of this byproduct stream. Unfortunately, while the concentration of this effluent is generally high in hydrogen (>90% typically), the presence of the acetylene waste product can act as a poison for the ruthenium-alumina catalyst used in the CO2-reducing Sabatier process, requiring a removal step. Metal-organic frameworks (MOFs) represent a valuable method for removing these unsaturated hydrocarbons due to their high tunability, particularly through the incorporation of open metal sites. In this study, two common iron-based MOFs, MIL-100 and PCN-250, were studied for their ability to adsorb acetylene. A combination of gas adsorption analysis and density functional theory calculation results shows the ability of these materials to undergo a thermal-induced reduction event, which results in an improvement in gas adsorption performance. This improvement in gas performance appears to be at least partially due to the increased presence of π-backbonding toward the acetylene molecules.

A mid-infrared exhaled carbon dioxide isotope detection system based on 4.35 μm quantum cascade laser

The carbon dioxide isotope in human exhaled gas can be used as an indicator to determine Helicobacter pylori (HP), the detection of carbon dioxide isotope in human exhaled gas is of great significance for the treatment of human diseases. Based on Tunable Diode Laser Absorption Spectroscopy (TDLAS), a carbon dioxide isotope detection system for exhaled gas was developed to detect the carbon dioxide isotope in human exhaled gas, a 4.35 μm quantum cascade laser (QCL) and a 3 m optical path multi-pass gas cell (MPGC) were adopted in the detection system. The exhaled gas pretreatment system was designed to pass through human exhaled gas into the MPGC. The performance of the system was researched using a gas distribution station fitted with standard 12CO2 and 13CO2 concentrations. The results show that the limits of detection（LOD）of 12CO2 and 13CO2 reach up ∼ 0.0134 ppm and ∼ 0.0149 ppm, respectively. The detection precision of the system is ∼ 0.00214 ‰ with a 48 s averaging time. QCL-based mid-infrared detection system has higher sensitivity and lower detection limit compared with near-infrared detection system. The volume of MPGC is 250 ml, which is much less than the volume of normal human exhaled gas, therefore the majority of human exhaled gas can be filled with MPGC. Two-stage proportional-integral-derivative (PID) temperature control is adopted to eliminate the effect of drift of the spectrum due to the change of temperature, so that the stability of the system is improved. A high precision and high-speed Genetic Algorithm Extreme Learning Machine (GA-ELM) algorithm is applied for improving the concentration inversion precision of the system. Finally, the performance of detection system was validated at Sichuan Cancer Hospital for detecting carbon dioxide isotope in exhaled gas, and the verification results illustrate that the detection system has a very important application prospect in the field of exhaled gas detection.

Assessment of neonatal respiratory rate variability

Accurate measurement of respiratory rate (RR) in neonates is challenging due to high neonatal RR variability (RRV). There is growing evidence that RRV measurement could inform and guide neonatal care. We sought to quantify neonatal RRV during a clinical study in which we compared multiparameter continuous physiological monitoring (MCPM) devices. Measurements of capnography-recorded exhaled carbon dioxide across 60-s epochs were collected from neonates admitted to the neonatal unit at Aga Khan University-Nairobi hospital. Breaths were manually counted from capnograms and using an automated signal detection algorithm which also calculated mean and median RR for each epoch. Outcome measures were between- and within-neonate RRV, between- and within-epoch RRV, and 95% limits of agreement, bias, and root-mean-square deviation. Twenty-seven neonates were included, with 130 epochs analysed. Mean manual breath count (MBC) was 48 breaths per minute. Median RRV ranged from 11.5% (interquartile range (IQR) 6.8–18.9%) to 28.1% (IQR 23.5–36.7%). Bias and limits of agreement for MBC vs algorithm-derived breath count, MBC vs algorithm-derived median breath rate, MBC vs algorithm-derived mean breath rate were − 0.5 (− 2.7, 1.66), − 3.16 (− 12.12, 5.8), and − 3.99 (− 11.3, 3.32), respectively. The marked RRV highlights the challenge of performing accurate RR measurements in neonates. More research is required to optimize the use of RRV to improve care. When evaluating MCPM devices, accuracy thresholds should be less stringent in newborns due to increased RRV. Lastly, median RR, which discounts the impact of extreme outliers, may be more reflective of the underlying physiological control of breathing.

Compact carbon dioxide sensor using tunable diode laser absorption spectroscopy for capnographic monitoring

In order to realize real-time capnographic monitoring, a compact carbon dioxide sensor based on tunable diode laser spectroscopy technology was developed by means of a 2004 nm distributed feedback laser and a circular gas cell. The toroidal cell can achieve an optical path length of 3.49 m in a volume of 38 ml, which enables the tunable diode laser spectroscopy carbon dioxide sensor to achieve a detection limit of 175 ppm at a measurement rate of 12.5 Hz. The actual exhaled carbon dioxide gas detection experiments were implemented, including the breath analysis of a normal subject under different conditions and another subject with pneumothorax. It indicates that the sensor has good effectiveness and practicability for carbon dioxide metabolic monitoring and related disease diagnosis.

Species-Specificity in Thermopreference and CO2-Gated Heat-Seeking in Culex Mosquitoes.

Simple SummaryMosquitoes are cold-blooded insects whose body temperature and metabolism are largely affected by environmental temperature. These blood-sucking insects use heat emanating from their potential hosts to locate them for feeding, which is how they spread deadly diseases. They also use other cues, including exhaled carbon dioxide and other body odors emitted by the hosts. Interestingly, every species displays specific preferences for a range of ambient temperatures and blood hosts, which includes both warm- and cold-blooded animals. To better understand the role of heat in these contexts, we studied female mosquitoes of three species that differ in their location of origin and in their host preference: Culex territans, Cx. tarsalis, and Cx. quinquefasciatus. We analyzed their preference towards specific ambient temperatures and quantified their heat-seeking behaviors in the presence of CO2 at different concentrations. We found contrasting differences between these species, which reflects their native habitat and their host preference.Combining thermopreference (Tp) and CO2-gated heat-seeking assays, we studied the thermal preferendum and response to thermal cues in three Culex mosquito species exhibiting differences in native habitat and host preference (e.g., biting cold and/or warm-blooded animals). Results show that these species differ in both Tp and heat-seeking behavior. In particular, we found that Culex territans, which feed primarily on cold-blood hosts, did not respond to heat during heat-seeking assays, regardless of the CO2 concentration, but exhibited an intermediate Tp during resting. In contrast, Cx. quinquefasciatus, which feeds on warm blooded hosts, sought the coolest locations on a thermal gradient and responded only moderately to thermal stimuli when paired with CO2 at higher concentrations. The third species, Cx. tarsalis, which has been shown to feed on a wide range of hosts, responded to heat when paired with high CO2 levels and exhibited a high Tp. This study provides the first insights into the role of heat and CO2 in the host seeking behavior of three disease vectors in the Culex genus and highlights differences in preferred resting temperatures.

Hemodynamic and ventilatory changes in pediatric patients with special needs: A comparative clinical study.

Very limited data are available on the hemodynamic and ventilatory changes during sedation and general anesthesia using bispectral index (BIS) monitoring in intellectually disabled children. The purpose was to determine the hemodynamic and ventilatory changes after propofol and sevoflurane administration in children with special needs (CSN) versus healthy children (HC) during dental treatment. Forty pediatric patients needing dental treatment were allocated into two groups: children without systemic disease (healthy children [HC]) and mentally disabled children (children with special needs [CSN]). Sevoflurane in oxygen (100% oxygen, 5 l/min) and continuous propofol infusion (target-controlled infusion [TCI], 2 µg/ml) were used as sedative agents, and 2% lidocaine with 1:80,000 adrenaline was used as local anesthesia in both groups. Heart rate (HR), oxygen saturation (SaO2), respiratory rate (RR), exhaled carbon dioxide (CO2), blood pressure (BP) and bispectral monitoring (BIS) values were recorded during the entire dental treatment procedure. A statistically significant decrease in systolic BP, diastolic BP and RR was observed, with no significant differences between the healthy and disabled groups. In contrast, the HR and BIS values were lower in the CSN group than in the healthy patients (p ≤ 0.05). Patients with special needs had lower HR and BIS values than healthy patients, while BP, SaO2 and exhaled CO2 showed similar results in both groups. Key words:Bispectral index, hemodynamic changes, ventilatory changes, pediatric patients, special needs.

Correlation between changes in arterial blood oxygen partial pressure, oxygen uptake and carbon dioxide elimination by the lungs with changes in positive end expiratory pressure: a prospective observational study

INTRODUCTION: Since mechanical ventilation remains the main tool of respiratory support, ventilatory aspect of lung function fixed researchers’ attention during last decades, which is reflected by open lung concept and lung-protective ventilation strategy. However, it seems logical to assess function of the lung — biphasic mass exchanger with limited capacity — measuring its gas exchange performance, depending upon lung perfusion the same extent as ventilation. Recently clinicians have got routine access to metabolographers, providing figures of lungs oxygen absorption (VO2) and carbon dioxide exhalation (VCO2). OBJECTIVE: To evaluate interchangeability of metabolographer data and arterial blood gases analysis as tools for positive end-expiratory pressure (PEEP) titration by comparison of dynamic VO2 and VCO2 changes with PaO2 shifts after standardized PEEP changing. MATERIALS AND METHODS: A single-center prospective observational study included 41 patients underwent mechanical ventilation during general anesthesia for elective non-cardiothoracic surgery. After anesthesia induction and monitored parameters stabilization, PaO2, VCO2 and VO2 were measured before and after PEEP increasing from 2 to 5 mbar. Correlation was evaluated using Spearman coefficient in R-Studio with ggplot2 visualization package. RESULTS: After PEEP level increase, in 14 patients PaO2 changes were &lt; 5 %, in 15 patients PaO2 increase was observed, and in 12 patients PaO2 has decreased. The Spearman correlation coefficient (rh) between VCO2 and PaO2 was 0.77 (р-value = 3.75 × 10−9), between VO2 and PaO2 — rh = 0.92 (p-value = 2.2 × 10−16). CONCLUSIONS: The VCO2 and VO2 dynamic changes obtained using metabolographer demonstrates high correlation with PaO2 shifts followed PEEP changes, which makes the dynamic analysis of the first two indicators a possible non-invasive alternative for repeated arterial blood gases analysis during РЕЕР level titration. Notable fact is that in significant proportion of observations, PEEP level of 5 mbar, often recommended “by default” for lung-protective ventilation, is excessive from gas exchange performance point of view.

Exhaled Carbon Dioxide as a Physiological Source of Deterioration of Indoor Air Quality in Non-Industrial Environments: Influence of Air Temperature

People are the main reason for the deterioration of indoor air quality (IAQ) due to the continuous physiological metabolism processes in their bodies, including respiration. We present results from an investigation of the influence of indoor air temperature on the concentration of exhaled carbon dioxide (CO2). The investigation was preconditioned by previous findings on the effect of air temperature on human metabolism. However, our literature survey showed a lack of studies on the influence of the indoor air temperature on the exhaled CO2 (or metabolic CO2), which leads to the novelty of our results. Our experiments had two phases: measurement in a university classroom with an installed heating, ventilation, and air-conditioning (HVAC) system during regular classes and measurement in a specially designed small climate chamber, where the time variations of the CO2 concentrations, together with some physiological parameters, were measured. Two indoor air temperatures were set: 23 °C and 27 °C. The results obtained and their respective analyses show the strong effect of the two air temperatures on the CO2 concentration due to exhalation. In the classroom, the CO2 concentration at 27 °C was higher by 6.2% than at 23 °C. In the climate chamber, the CO2 concentration at 27 °C was higher by 9.6% than at 23 °C. Physiological parameters (oxygen saturation pressure, pulse rate, end-tidal CO2, and respiration rate) and their dependence on the air temperature were also measured in the climate chamber, establishing an effect of the temperature on the pulse rate.

Nanotechnology Innovations to Enhance the Therapeutic Efficacy of Quercetin.

Quercetin is a flavonol present in many vegetables and fruits. Generally, quercetin can be found in aglycone and glycoside forms, mainly in leaves. The absorption of this compound occurs in the large and small intestine, where it suffers glucuronidation, sulfidation, and methylation to improve hydrophilicity. After metabolization, which occurs mainly in the gut, it is distributed throughout the whole organism and is excreted by feces, urine, and exhalation of carbon dioxide. Despite its in vitro cytotoxicity effects, in vivo studies with animal models ensure its safety. This compound can protect against cancer, cardiovascular diseases, chronic inflammation, oxidative stress, and neurodegenerative diseases due to its radical scavenging and anti-inflammatory properties. However, its poor bioavailability dampens the potential beneficial effects of this flavonoid. In that sense, many types of nanocarriers have been developed to improve quercetin solubility, as well as to design tissue-specific delivery systems. All these studies manage to improve the bioavailability of quercetin, allowing it to increase its concentration in the desired places. Collectively, quercetin can become a promising compound if nanotechnology is employed as a tool to enhance its therapeutic efficacy.

Identification of thresholds for accuracy comparisons of heart rate and respiratory rate in neonates.

Background: Heart rate (HR) and respiratory rate (RR) can be challenging to measure accurately and reliably in neonates. The introduction of innovative, non-invasive measurement technologies suitable for resource-constrained settings is limited by the lack of appropriate clinical thresholds for accuracy comparison studies. Methods: We collected measurements of photoplethysmography-recorded HR and capnography-recorded exhaled carbon dioxide across multiple 60-second epochs (observations) in enrolled neonates admitted to the neonatal care unit at Aga Khan University Hospital in Nairobi, Kenya. Trained study nurses manually recorded HR, and the study team manually counted individual breaths from capnograms. For comparison, HR and RR also were measured using an automated signal detection algorithm. Clinical measurements were analyzed for repeatability. Results: A total of 297 epochs across 35 neonates were recorded. Manual HR showed a bias of -2.4 (-1.8%) and a spread between the 95% limits of agreement (LOA) of 40.3 (29.6%) compared to the algorithm-derived median HR. Manual RR showed a bias of -3.2 (-6.6%) and a spread between the 95% LOA of 17.9 (37.3%) compared to the algorithm-derived median RR, and a bias of -0.5 (1.1%) and a spread between the 95% LOA of 4.4 (9.1%) compared to the algorithm-derived RR count. Manual HR and RR showed repeatability of 0.6 (interquartile range (IQR) 0.5-0.7), and 0.7 (IQR 0.5-0.8), respectively. Conclusions: Appropriate clinical thresholds should be selected a priori when performing accuracy comparisons for HR and RR. Automated measurement technologies typically use a smoothing or averaging filter, which significantly impacts accuracy. A wider spread between the LOA, as much as 30%, should be considered to account for the observed physiological nuances and within- and between-neonate variability and different averaging methods. Wider adoption of thresholds by data standards organizations and technology developers and manufacturers will increase the robustness of clinical comparison studies.