Exhaled CO2 Research Articles

Vampire bats rapidly fuel running with essential or non-essential amino acids from a blood meal.

In most mammals, running is fuelled by oxidization of endogenous carbohydrates and lipids while amino acids contribute little (< 5-10%). Common vampire bats (Desmodus rotundus), however, specialize on a unique, protein-rich blood diet. Therefore, we hypothesized that (i) vampire bats would rapidly begin utilizing dietary amino acids to support running metabolism, and (ii) that relative reliance on essential and non-essential amino acids would be similar. We fed bats cow's blood enriched either with isotopically labelled glycine (non-essential amino acid) or leucine (essential amino acid). Bats were exercised at speeds of 10, 20 and 30 m min-1 on a respirometry treadmill, allowing us to assess metabolic rate (i.e. O2 consumption and CO2 production) and track the oxidation of labelled amino acids in exhaled CO2. Vampire bats oxidized amino acids as their primary fuel as indicated by a respiratory exchange ratio (RER = ratio of CO2 production to O2 consumption rates) of approximately 0.8-0.9 at all speeds, with the labelled meal accounting for as much as 60% of oxidized fuels at peak usage. Similar oxidation rates indicated bats did not discriminate between essential and non-essential amino acid use. These findings reiterate how strongly metabolism can be shaped by a specialized diet.

Relationships between capnogram parameters by mainstream and sidestream techniques at different breathing frequencies

Capnography, routinely used in operating rooms and intensive care units, reveals essential information on lung ventilation and ventilation–perfusion matching. Mainstream capnography directly measures CO2 in the breathing circuit for accurate analysis and is considered a reference technique. Sidestream capnography, however, analyzes gas away from the patient leading to potentially less accurate measures. While these methodological differences impact the capnogram indices in mechanically ventilated patients, such assessments during spontaneous breathing are essentially lacking. Accordingly, we aimed to compare mainstream and sidestream capnography in spontaneously breathing subjects, focusing on differences in capnogram shape and dead space indices at various respiratory rates. Simultaneous mainstream and sidestream time and volumetric capnography were performed on spontaneously breathing adults (n = 35). Measurements were performed during controlled low (10/min), medium (12/min), and high (20/min) breathing rates as a challenge. Correlation and Bland–Altman analyses were used to assess trends and agreements between time and volumetric capnography indices obtained by the mainstream and sidestream techniques, including end-tidal CO2 (ETCO2), shape factors reflecting the slopes of phases 2 and 3, and anatomical and physiological dead space fractions. ETCO2 and physiological dead space measured by mainstream and sidestream techniques showed excellent correlations (r > 0.90, p < 0.001 for all breathing rates) and agreements. While strong correlations and moderate agreements were evidenced in the parameters reflecting the late phase of expiration (phase 3 slope and exhaled CO2 volume), these relationships were weaker for indices related to the early phase of expiration (phase 2 slope, anatomical dead space). Changing breathing frequency caused significant alterations in all capnography parameters, which were detectable by both mainstream and sidestream techniques. Sidestream capnography cannot substitute the more accurate mainstream technique for measuring the absolute values of shape factors and ventilation dead space fractions. However, sidestream capnography is also able to detect and track changes in uneven alveolar emptying, ventilation–perfusion matching and ventilation dead space fraction in spontaneously breathing subjects.

Quartz enhanced low sampling trace gas detection

Abstract Dectection of the exhaled gas, which can effectively reflect human health status, analyze and predict diseases has become a research focus. Quartz enhanced photoacoustic spectroscopy (QEPAS) technology has the advantages of small volume, low cost, and high sensitivity, exhibiting great potential in exhaled gas detection. In this work, small volume fractions of CO were detected by QEPAS technology. Optimizing the structure based on finite element method and designing circuit, a detection system with adjustable photoacoustic cell pressure was established. Then, the corresponding relationship between gas volume fraction and response signal was calibrated by the detection of multiple volume fractions of CO. The system has shown a volume fraction detection limit of 531.2×10−9, with a normalized noise equivalent absorption coefficient of 2.86×10−8 cm−1/Hz1/2 and an average detection error of less than 0.8%. The results indicate that our QEPAS system could monitor the exhaled CO trace gas, showing broad application prospects.

A Comprehensive Review of Carbon Capture, Utilization, and Storage (CCUS): Technological Advances, Environmental Impact, and Economic Feasibility

Carbon capture, utilisation, and storage (CCUS) technologies are critical to reducing CO2 exhalations on a global scale. This review study synthesizes the many elements of CCUS over 50 years, from R&amp;D to deployment scales, in terms of their mitigation potential for global emission reductions. Next, it discusses existing and new carbon capture techniques from an automation standpoint (e.g., pre-combustion capture, post-combustion capture combustion), as well as the economic feasibility of CCUS regionally in terms of capital retail price, operating expenses, and value in the form of potential revenue streams based on CO2, aided by significant range-scaling building blocks such as rising nation. Each technique is thoroughly evaluated in terms of its environmental impact and associated risks, and case studies are used to illustrate practical lessons learnt. The paper also discusses the arguments around what future advances may exist in CCUS technology, and opportunities to scale these up (including research needs for this support), drawing lessons past policy. The findings underscore the importance of integrating CCUS into broader climate strategies to achieve net-zero exhalations while addressing the economic and environmental challenges that remain.

Relationship between Exhaled Aerosol and Carbon Dioxide Emission Across Respiratory Activities.

Respiratory particles produced during vocalized and nonvocalized activities such as breathing, speaking, and singing serve as a major route for respiratory pathogen transmission. This work reports concomitant measurements of exhaled carbon dioxide volume (VCO2) and minute ventilation (VE), along with exhaled respiratory particles during breathing, exercising, speaking, and singing. Exhaled CO2 and VE measured across healthy adult participants follow a similar trend to particle number concentration during the nonvocalized exercise activities (breathing at rest, vigorous exercise, and very vigorous exercise). Exhaled CO2 is strongly correlated with mean particle number (r = 0.81) and mass (r = 0.84) emission rates for the nonvocalized exercise activities. However, exhaled CO2 is poorly correlated with mean particle number (r = 0.34) and mass (r = 0.12) emission rates during activities requiring vocalization. These results demonstrate that in most real-world environments vocalization loudness is the main factor controlling respiratory particle emission and exhaled CO2 is a poor surrogate measure for estimating particle emission during vocalization. Although measurements of indoor CO2 concentrations provide valuable information about room ventilation, such measurements are poor indicators of respiratory particle concentrations and may significantly underestimate respiratory particle concentrations and disease transmission risk.

Role of exhaled carbon monoxide in assessment of chronic obstructive airway disease severity

BackgroundChronic obstructive pulmonary disease (COPD) is a critical public health issue. Spirometric measurements are used to diagnose chronic obstructive lung disease, as per the guidelines of the GOLD initiative. Post-bronchodilator forced expiratory volume in 1 s (FEV1) is a predictor of mortality from COPD and helps to classify the disease’s severity. Smoking contributes to the high levels of exhaled CO. Evidence suggests that the exhaled CO level in COPD patients varies with degree of blockage and can be used to assess treatment response. Estimating the exhaled CO level can help assess airway inflammation and severity of airflow obstruction in individuals with COPD.AimEvaluate role of exhaled CO in assessment of severity of COPD.Materials and methodsThis cross-sectional study included 132 patients who visited the outpatient clinics or were admitted to the Chest Department, Kasr Alainy Hospital, Faculty of Medicine, Cairo University. The study participants were divided into three groups: group 1 nonsmoker healthy control, group 2 smoker non-COPD, and group 3 smoker COPD which further divided according to GOLD 2023 into mild, moderate, and severe COPD. The smoking status, exhaled CO, and spirometry test including FEV1/FVC and FEV1 were measured for each patient.ResultsExhaled CO was significantly increased in the smoker group (mean 9.69, SD 3.11) compared to the nonsmoker group (mean 2.19, SD 0.98) with p-value < 0.001. Exhaled CO was also statistically significantly higher in the smoker COPD group (mean 10.45, SD 3.03) compared to the smoker non-COPD group (mean 7.05, SD 1.56) with p-value < 0.001. Although exhaled CO was increased in the severe COPD group compared to the mild and moderate group, there is no statistically significant difference between them.ConclusionExhaled CO is a fast, sensitive, noninvasive, and well-established method test that can be used to identify smokers from nonsmokers with 98.9% sensitivity at 4.5 cutoff value. Also, exhaled CO levels in COPD patients vary with different degrees of airway obstruction.

Changes in Exhaled Carbon Dioxide during the Menstrual Cycle and Menopause

Introduction: The menstrual cycle (MC) reflects multifaceted hormonal changes influencing women’s metabolism, making it a key aspect of women’s health. Changes in hormonal levels throughout the MC have been demonstrated to influence various physiological parameters, including exhaled carbon dioxide (CO2). Lumen is a small handheld device that measures metabolic fuel usage via exhaled CO2. This study leverages exhaled CO2 patterns measured by the Lumen device to elucidate metabolic variations during the MC, which may hold significance for fertility management. Additionally, CO2 changes are explored in menopausal women with and without hormonal replacement therapy (HRT). Methods: This retrospective cohort study analyzed exhaled CO2 data from 3,981 Lumen users, including eumenorrheal women and menopausal women with and without HRT. Linear mixed models assessed both CO2 changes of eumenorrheal women during the MC phases and compared between menopausal women with or without HRT. Results: Eumenorrheic women displayed cyclical CO2 patterns during the MC, characterized by elevated levels during the menstrual, estrogenic and ovulation phases and decreased levels during post-ovulation and pre-menstrual phases. Notably, despite variations in cycle length affecting the timing of maximum and minimum CO2 levels within a cycle, the overall pattern remained consistent. Furthermore, CO2 levels in menopausal women without HRT differed significantly from those with HRT, which showed lower levels. Conclusion: This study reveals distinct CO2 patterns across MC phases, providing insights into hormonal influences on metabolic activity. Menopausal women exhibit altered CO2 profiles in relation to the use or absence of HRT. CO2 monitoring emerges as a potential tool for tracking the MC and understanding metabolic changes during menopause.

A numerical framework for the analysis of indoor air quality in a classroom

This paper presents a framework for applying Computational Fluid Dynamics (CFD) to study indoor air quality in a classroom environment by analysing the transport and extent of human-generated aerosol and carbon dioxide (CO2) accumulation. A methodology is outlined for identifying the appropriate amounts of exhaled aerosol and CO2 needed as boundary conditions for human breathing in CFD simulations, which is validated with in situ measurements obtained within a stale air classroom environment at matched conditions. This is crucial for quantifying the exhaled CO2 and aerosols from occupants, which is essential for designing ventilation settings that promote a healthy indoor environment. Good agreement is observed between the CFD and experiments for CO2 and aerosol concentration within the size range of 0.7-1μm. Further, we explore the impact of individual heat sources and breathing momentum flux on air stratification and aerosol dispersion. The analysis reveals that the thermal plume generated by each occupant and the momentum created from breathing are the characteristics of airflow in a stale air environment. This paper demonstrates the ability of the developed numerical model to reproduce realistic exhaled aerosol and CO2 in indoor ventilation settings, serving as a benchmark for investigating indoor air quality in the built environment.

The Association of Macronutrient Consumption and BMI to Exhaled Carbon Dioxide in Lumen Users: Retrospective Real-World Study.

Metabolic flexibility is the ability of the body to rapidly switch between fuel sources based on their accessibility and metabolic requirements. High metabolic flexibility is associated with improved health outcomes and a reduced risk of several metabolic disorders. Metabolic flexibility can be improved through lifestyle changes, such as increasing physical activity and eating a balanced macronutrient diet. Lumen is a small handheld device that measures metabolic fuel usage through exhaled carbon dioxide (CO2), which allows individuals to monitor their metabolic flexibility and make lifestyle changes to enhance it. This retrospective study aims to examine the postprandial CO2 response to meals logged by Lumen users and its relationship with macronutrient intake and BMI. We analyzed deidentified data from2607 Lumen users who logged their meals and measured their exhaled CO2 before and after those meals between May 1, 2023, and October 18, 2023. A linear mixed model was fitted to test the association between macronutrient consumption, BMI, age, and gender to the postprandial CO2 response, followed by a 2-way ANOVA. The model demonstrated significant associations (P<.001) between CO2 response after meals and both BMI and carbohydrate intake (BMI: β=-0.112, 95% CI -0.156 to -0.069; carbohydrates: β=0.046, 95% CI 0.034-0.058). In addition, a 2-way ANOVA revealed that higher carbohydrate intake resulted in a higher CO2 response compared to low carbohydrate intake (F2,2569=24.23; P<.001), and users with high BMI showed modest responses to meals compared with low BMI (F2,2569=5.88; P=.003). In this study, we show that Lumen's CO2 response is influenced both by macronutrient consumption and BMI. The results of this study highlight a distinct pattern of reduced metabolic flexibility in users with obesity, indicating the value of Lumen for assessing postprandial metabolic flexibility.

In utero smoking exposure induces changes to lung clearance index and modifies risk of wheeze in infants.

Fetal exposure to tobacco smoking throughout pregnancy is associated with wheezing in infancy. We investigated the influence of in utero smoking exposure on lung ventilation homogeneity and the relationship between lung ventilation inhomogeneity at 7 weeks of age and wheezing in the first year of life. Maternal smoking was defined as self-reported smoking of tobacco or validated by exhaled (e)CO > 6 ppm. Lung function data from healthy infants (age 5-9 weeks) born to asthmatic mothers and parent-reported respiratory questionnaire data aged 12 months were collected in the Breathing for Life Trial (BLT) birth cohort. Tidal breathing analysis and SF6-based Multiple Breath Washout testing were performed in quiet sleep. Descriptive statistics and regression analysis were used to assess associations. Data were collected on 423 participants. Infants born to women who self-reported smoking during pregnancy (n = 42) had higher lung clearance index (LCI) than those born to nonsmoking mothers (7.90 vs. 7.64; p = .030). Adjusted regression analyzes revealed interactions between self-reported smoking and LCI (RR: 1.98, 95% CI: 1.07-3.63, 0.028, for each unit increase in LCI) and between eCO > 6 ppm and LCI (RR: 2.25, 95% CI: 1.13-4.50, 0.022) for the risk of wheeze in the first year of life. In utero tobacco smoke exposure induces lung ventilation inhomogeneities. Furthermore, an interaction between smoke exposure and lung ventilation inhomogeneities increases the risk of having a wheeze in the first year of life.

Water restriction increases oxidation of endogenous amino acids in house sparrows (Passer domesticus).

Animals can cope with dehydration in a myriad of ways, both behaviorally and physiologically. The oxidation of protein produces more metabolic water per kilojoule than that of fat or carbohydrate, and it is well established that birds increase protein catabolism in response to high rates of water loss. However, the fate of amino acids mobilized in response to water restriction has not been explicitly determined. While protein catabolism releases bound water, we hypothesized that water-restricted birds would also oxidize the resulting amino acids, producing additional water as a product of oxidative phosphorylation. To test this, we fed captive house sparrows (Passer domesticus) 13C-labeled leucine for 9 weeks to label endogenous proteins. We conducted weekly trials during which we measured the physiological response to water restriction as changes in lean mass, fat mass, metabolism and the enrichment of 13C in exhaled CO2 (δ13Cbreath). If water-restricted birds catabolized proteins and oxidized the resulting amino acids, we expected to simultaneously observe greater lean mass loss and elevated δ13Cbreath relative to control birds. We found that water-restricted birds catabolized more lean tissue and also had enriched δ13Cbreath in response to water restriction, supporting our hypothesis. δ13Cbreath, however, varied with metabolic rate and the length of the water restriction period, suggesting that birds may spare protein when water balance can be achieved using other physiological strategies.

Metabolic plasticity and obesity-associated changes in diurnal postexercise metabolism in mice

BackgroundCircadian disruption is widespread and increases the risk of obesity. Timing of therapeutic interventions may promote coherent and efficient gating of metabolic processes and restore energy homeostasis. AimTo characterize the diurnal postexercise metabolic state in mice and to identify the influence of diet-induced obesity on identified outcomes. MethodsC57BL6/NTac male mice (6 wks of age) were fed a standard chow or high-fat diet for 5 weeks. At week 5, mice were subjected to a 60-min (16 m/min, 5 % incline) running bout (or sham) during the early rest (day) or early active (night) phase. Tissue and serum samples were collected immediately post-exercise (n = 6/group). In vivo glucose oxidation was measured after oral administration of 13C-glucose via 13CO2 exhalation analysis in metabolic cages. Basal and isoproterenol-stimulated adipose tissue lipolysis was assessed ex vivo for 1 h following exercise. ResultsLean mice displayed exercise-timing-specific plasticity in metabolic outcomes, including phase-specificity in systemic glucose metabolism and adipose-tissue-autonomous lipolytic activity depending on time of day. Conversely, obesity impaired temporal postexercise differences in whole-body glucose oxidation, as well as the phase- and exercise-mediated induction of lipolysis in isolated adipose tissue. This obesity-induced alteration in diurnal metabolism, as well as the indistinct response to exercise, was observed concomitant with disruption of core clock gene expression in peripheral tissues. ConclusionsOverall, high-fat fed obese mice exhibit metabolic inflexibility, which is also evident in the diurnal exercise response. Our study provides physiological insight into exercise timing-dependent aspects in the dynamic regulation of metabolism and the influence of obesity on this biology.

Effects of periodic breathing on sleep at high altitude: a randomized, placebo-controlled, crossover study using inspiratory CO2.

Hypoxia at high altitude facilitates changes in ventilatory control that can lead to nocturnal periodic breathing (nPB). Here, we introduce a placebo-controlled approach to prevent nPB by increasing inspiratory CO2 and used it to assess whether nPB contributes to the adverse effects of hypoxia on sleep architecture. In a randomized, single-blinded, crossover design, 12 men underwent two sojourns (three days/nights each, separated by 4weeks) in hypobaric hypoxia corresponding to 4000m altitude, with polysomnography during the first and third night of each sojourn. During all nights, subjects' heads were encompassed by a canopy retaining exhaled CO2 , and CO2 concentration in the canopy (i.e. inspiratory CO2 concentration) was controlled by adjustment of fresh air inflow. Throughout the placebo sojourn inspiratory CO2 was ≤0.2%, whereas throughout the other sojourn it was increased to 1.76% (IQR, 1.07%-2.44%). During the placebo sojourn, total sleep time (TST) with nPB was 54.3% (37.4%-80.8%) and 45.0% (24.5%-56.5%) during the first and the third night, respectively (P=0.042). Increased inspiratory CO2 reduced TST with nPB by an absolute 38.1% (28.1%-48.1%), the apnoea-hypopnoea index by 58.1/h (40.1-76.1/h), and oxygen desaturation index ≥3% by 56.0/h (38.9.1-73.2/h) (all P<0.001), whereas it increased the mean arterial oxygen saturation in TST by 2.0% (0.4%-3.5%, P=0.035). Increased inspiratory CO2 slightly increased the percentage of N3sleep during the third night (P=0.045), without other effects on sleep architecture. Increasing inspiratory CO2 effectively prevented hypoxia-induced nPB without affecting sleep macro-architecture, indicating that nPB does not explain the sleep deterioration commonly observed at high altitudes. KEY POINTS: Periodic breathing is common during sleep at high altitude, and it is unclear how this affects sleep architecture. We developed a placebo-controlled approach to prevent nocturnal periodic breathing (nPB) with inspiratory CO2 administration and used it to assess the effects of nPB on sleep in hypobaric hypoxia. Nocturnal periodic breathing was effectively mitigated by an increased inspiratory CO2 fraction in a blinded manner. Prevention of nPB did not lead to relevant changes in sleep architecture in hypobaric hypoxia. We conclude that nPB does not explain the deterioration in sleep architecture commonly observed at high altitude.

Utility of non-invasive monitoring of exhaled carbon dioxide and perfusion index in adult patients in the emergency department

BackgroundSeveral noninvasive solutions are available for the assessment of patients at risk of deterioration. Capnography, in the form of end-tidal exhaled CO2 (ETCO2) and perfusion index (PI), could provide relevant information about patient prognosis. The aim of the present project was to determine the association of ETCO2 and PI with mortality of patients admitted to the emergency department (ED). MethodsMulticenter, prospective, cohort study of adult patients with acute disease who needed continuous monitoring in the ED. The study included two tertiary hospitals in Spain between October 2022 and June 2023. The primary outcome of the study was in-hospital mortality (all-cause). Demographics, vital signs, ETCO2 and PI were collected. ResultsA total of 687 patients were included in the study. The in-hospital mortality rate was 6.8%. The median age was 79 years (IQR: 69–86), and 63.3% were males. The median ETCO2 value was 30 mmHg (26–35) in survivors and 23 mmHg (16–30) in nonsurvivors (p = 0.001). For the PI, the medians were 4.7% (2.8–8.1) for survivors and 2.5% (0.98–4-4) for nonsurvivors (p < 0.001). The model that presented the best AUC was age (odds ratio (OR): 1.02 (1.00–1.05)), the respiratory rate (OR: 1.06 (1.02–1.11)), and the PI (OR: 0.83 (0.75–0.91)), with a result of 0.840 (95% CI: 0.795–0.886); the model with the respiratory rate (OR: 1.05 (1.01–1.10)), the PI (OR: 0.84 (0.76–0.93)), and the ETCO2 (no statistically significant OR), with an AUC of 0.838 (95% CI: 0.787–0.889). ConclusionsThe present study showed that the PI and respiratory rate are independently associated with in-hospital mortality. Both the PI and ETCO2 are predictive parameters with improved prognostic performance compared with that of standard vital signs.

Real-Time Measurement of CH4 in Human Breath Using a Compact CH4/CO2 Sensor.

The presence of an elevated amount of methane (CH4) in exhaled breath can be used as a non-invasive tool to monitor certain health conditions. A compact, inexpensive and transportable CH4 sensor is thus very interesting for this purpose. In addition, if the sensor is also able to simultaneously measure carbon dioxide (CO2), one can extract the end-tidal concentration of exhaled CH4. Here, we report on such a sensor based on a commercial detection module using tunable diode laser absorption spectroscopy. It was found that the measured CH4/CO2 values exhibit a strong interference with water vapor. Therefore, correction functions were experimentally identified and validated for both CO2 and CH4. A custom-built breath sampler was developed and tested with the sensor for real-time measurements of CH4 and CO2 in exhaled breath. As a result, the breath sensor demonstrated the capability of accurately measuring the exhaled CH4 and CO2 profiles in real-time. We obtained minimum detection limits of ~80 ppbv for CH4 and ~700 ppmv for CO2 in 1.5 s measurement time.

Skin temperature influence on transcutaneous carbon dioxide (CO2) conductivity and skin blood flow in healthy human subjects at the arm and wrist.

Objective: present transcutaneous carbon dioxide (CO2)-tcpCO2-monitors suffer from limitations which hamper their widespread use, and call for a new tcpCO2 measurement technique. However, the progress in this area is hindered by the lack of knowledge in transcutaneous CO2 diffusion. To address this knowledge gap, this study focuses on investigating the influence of skin temperature on two key skin properties: CO2 permeability and skin blood flow. Methods: a monocentric prospective exploratory study including 40 healthy adults was undertaken. Each subject experienced a 90 min visit split into five 18 min sessions at different skin temperatures-Non-Heated (NH), 35, 38, 41, and 44°C. At each temperature, custom sensors measured transcutaneous CO2 conductivity and exhalation rate at the arm and wrist, while Laser Doppler Flowmetry (LDF) assessed skin blood flow at the arm. Results: the three studied metrics sharply increased with rising skin temperature. Mean values increased from the NH situation up to 44°C from 4.03 up to 8.88 and from 2.94 up to 8.11 m·s-1 for skin conductivity, and from 80.4 up to 177.5 and from 58.7 up to 162.3 cm3·m-2·h-1 for exhalation rate at the arm and wrist, respectively. Likewise, skin blood flow increased elevenfold for the same temperature increase. Of note, all metrics already augmented significantly in the 35-38°C skin temperature range, which may be reached without active heating-i.e. only using a warm clothing. Conclusion: these results are extremely encouraging for the development of next-generation tcpCO2 sensors. Indeed, the moderate increase (× 2) in skin conductivity from NH to 44°C tends to indicate that heating the skin is not critical from a response time point of view, i.e. little to no skin heating would only result in a doubled sensor response time in the worst case, compared to a maximal heating at 44°C. Crucially, a skin temperature within the 35-38°C range already sharply increases the skin blood flow, suggesting that tcpCO2 correlates well with the arterial paCO2 even at such low skin temperatures. These two conclusions further strengthen the viability of non-heated tcpCO2 sensors, thereby paving the way for the development of wearable transcutaneous capnometers.

Examining the Impact of Fiscal Decentralization and Renewable Energy on CO2 Emissions: Insights from Pakistan

The relevance of fiscal decentralization in environmental sustainability cannot be overstated. Some believe that fiscal decentralization is essential to long-term environmental health. However, to what extent fiscal decentralization (FSD) hinders or promotes ecological sustainability is a topic of heated debate. Knowing how fiscal decentralization impacts the environment is vital because it cannot be disregarded while working toward the Sustainable Development Goals of a clean environment and minimizing climate change. This study determines the relationship between FSD, NRE, RNE, GDP, and CO2 excretion, taking data from 2005 to 2021. We employed the ARDL model to investigate the association between study variables. The empirical findings show that fiscal decentralization, NRE, and GDP exert beneficial effects on CO2 exhalation and harm the environment, while RNE cleans the environment by decreasing CO2 outflow; yet, all study variables are positively connected with the ecological footprint. Based on the recommendations for Pakistan, It is suggested that policymakers and the government of Pakistan should allocate funds for green infrastructure to combat CO2 emissions.

The Bilateral Tap-Block Ultrasound-Guided in Laparoscopic Abdominal Surgery: Evaluation of a Curare-Free Anaesthetic Protocol

Introduction: The transverse abdominal plane block or TAP block consists of injecting a local anaesthetic between the internal oblique and transverse muscles. Its contribution to muscle relaxation during laparoscopic surgery has been little studied. Material and Method: We carried out a 2-years prospective, descriptive and analytical randomised study blinded to the surgeon conducted in the operating theatre of the Saint Louis Regional Hospital Centre. Patients were randomised into two groups: those who received vecuronium after rapid sequence induction (group V) and those who received bilateral TAP block without curares (group T). Anamnestic, clinical, anaesthetic, surgical and evolutionary aspects were collected and analysed. The main evaluation criteria were: pneumoperitoneum pressure, exhaled CO2, respiratory motor pressure and surgeon satisfaction scale. Results: We collected 61 patients admitted for laparoscopic abdominal surgery. The mean age was 32.9 years with a standard deviation of 14.5. Appendicitis was the indication in 55% of cases. The Propofol-celocurine-TAP-block anaesthetic protocol was used in 25 patients, i.e. in 41% of cases, and 59% of patients had undergone a conventional induction using vecuronium. The mean pressure of the pneumoperitoneum was 11.3 mmHg for the conventional induction group and 12.6 mmHg for the TAP-block group. The mean respiratory motor pressures were 12 cmH2O for the conventional induction group and 13.7 cmH2O for the TAP-block group. The mean value of exhaled CO2 was 37.5 mmHg. Fentanyl reinjections were more frequent in the conventional induction group in 55.6% of cases. The mean VAS at 6 hours post-op was 4.5 for the conventional induction group and 3 for the TAP-block group. Discussion/Conclusion: The ultrasound-guided trans-abdominal-pelvic block remains an effective, durable and reproducible technique. Its advantages in terms of postoperative analgesia are well known. In addition, its selective effects on muscle ......

Pregnancy and tobacco: Practice and knowledge of French midwives

ObjectivesEvaluate the midwives’ practices and knowledges with regard to the management of the smoking cessation in pregnant women and analyse the profile of midwives prescribing nicotine replacement therapy (NRT). MethodsA national practice survey amongst 23,541 French midwives was conducted from 1 September 2020 to 15 September 2021 using an online self-administered questionnaire. ResultsThe analysis of the 1,216 usable questionnaires (97, 7% women, mostly aged 30 to 49 years and non-smokers) showed that 93.4% of midwives frequently questioned pregnant women about their smoking consumption during pregnancy. The minimal counselling was known and practiced by 91% of midwives, the Fagerström test by 26.9% and the measurement of exhaled CO by 27.1%. Concerning NRT, 60% of the midwives prescribed them in a usual way and 36.8% were aware of the possibility of prescribing them to the pregnant woman's entourage. The profile of midwives prescribing NRT was significantly more concerned with smoking cessation in pregnant women; worked more frequently in a hospital; carried out 25% or more of antenatal monitoring consultations; and had significantly better knowledge of the evaluation tools, without influence of sex or smoking status. ConclusionsImproving the training of midwives in the screening and management of smoking cessation during pregnancy seems necessary.

Abstract 432: Temporal Trends in End Tidal Capnography and Outcomes in Out of Hospital Cardiac Arrest

Background: While widely measured and used to direct resuscitation, the time-varying relationship between exhaled end-tidal CO2 (ETCO2) and out-of-hospital cardiac arrest (OHCA) outcomes is unclear. We sought to determine the association between temporal trends in ETCO2 and return of spontaneous circulation (ROSC) in the Pragmatic Airway Resuscitation Trial (PART). Methods: We analyzed data from the PART Trial, which tested endotracheal intubation or laryngeal tube strategies in OHCA resuscitation. Emergency medical services collected continuous ETCO2 recordings using defibrillator monitors. We identified maximal ETCO2 values for each ventilation using previously validated automated signal processing. We determined mean ETCO2 in one-minute(min) epochs from advanced airway insertion through ROSC or end of event. We included all cases with interpretable ETCO2 signal in at least one of the epochs. We compared discrete time points between ROSC and non-ROSC using one way Mann-Whitney and determined the association between temporal trends in ETCO2 comparing the slopes of ETCO2 over time. Results: We included 1147 of 3004 patients with available ETCO2 data. There were 225(20%) ROSC and 923(80%) non-ROSC cases. Mean duration of resuscitation was 16 and 27 minutes for ROSC and non-ROSC cases, respectively. In ROSC cases, ETCO2 increased from 26.8 to 48.9 mmHg over 20-min prior to ROSC. In non-ROSC cases, ETCO2 declined from 30.6 to 21.7 mmHg over the 20-min. Mean ETCO 2 between ROSC and non-ROSC cases did not differ at t-10 (30.6 mmHg vs 26.1 mmHg, p=0.07) or t-20 min (26.8 mmHg vs 30.6 mmHg, p=0.71). However, ETCO 2 changes over time differed between ROSC and non-ROSC (p&lt;0.01, figure 1). Conclusions: Upward temporal increases in ETCO 2 are associated with ROSC. Dynamic time-varying changes in ETCO2 may indicate OHCA outcomes.