Search Results (73)

To elucidate the changes in gas exchange across the life course, we estimated the age trajectories of O₂ saturation, CO₂ (as either end-tidal or serum bicarbonate), resting heart rate, and resting respiratory rate from age 2 yr onward in female and male patients separately. We utilized two sources’ data: electronic health records (EHR) representing ambulatory visits of approximately 53,000 individuals and sleep clinic polysomnogram (PSG) records representing an additional ~21,000. We used linear regression to estimate age-group-specific mean response levels for women and men. We compared estimated female–male differences between pre- and post-pubertal children and between pre- and post-menopausal periods among adults. Women between 15 and 45 years had higher O₂ saturation and lower serum bicarbonate levels or end-tidal CO₂ levels than men of similar ages. For O₂ saturation and for both measures of CO₂, the female–male difference was larger on average among adults at pre-menopausal ages than those at post-menopausal ages. Women had higher O₂ saturation throughout their lives than men; however, the difference disappeared in the elderly. Women between menarche and menopause had significantly lower end-tidal CO₂ and serum bicarbonate than men of similar ages. After menopause, however, women appeared to have higher mean levels of both end-tidal CO₂ and serum bicarbonate than men. Full article

Background/Objectives: Lung-protective ventilation (LPV) reduces postoperative pulmonary complications (PPCs) in obese patients. While the roles of low tidal volume and positive end-expiratory pressure (PEEP) in LPV have been established in patients with healthy lungs, the protective effect of alveolar recruitment strategies (ARSs) remains a subject of debate. This study aims to evaluate the benefit of ARSs in patients with low-to-moderate risk according to the Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) score undergoing gynecologic cancer surgery with LPV and low tidal volume intraoperatively. Methods: A total of 88 obese patients were evaluated in this study. They were divided into two groups as the non-ARS group (non-ARS) and the ARS group (ARS). Intraoperative hemodynamics, blood gas analyses, respiratory mechanics, mechanical ventilator parameters, and postoperative outcomes were compared in these obese patients. Results: A total of 40 obese patients undergoing major gynecological cancer surgery were included in this study. Although the non-ARS group presented with higher weight (p < 0.05), body mass indexes were similar to the ARS group. Intraoperative blood gas analysis revealed higher end-tidal carbon dioxide (etCO₂) levels in the non-ARS group during the T2 and T3 time intervals (p < 0.05). In the ARS group, peak inspiratory pressure (PIP) at T3 was lower, while drive pressures at T1 and T2 and dynamic compliance at T3 were higher (p < 0.05). Radiologic atelectasis scores were higher in the non-ARS group, indicating more atelectatic lung images (p < 0.05). PPC rates were similar across both groups. Conclusions: Although the ARS demonstrated positive effects on lung mechanics and radiologic atelectasis scores in major open gynecologic cancer surgeries, it did not effectively reduce postoperative pulmonary complications. Full article

Background/Objectives: Orthostatic intolerance is prevalent in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and is caused by an abnormal reduction in cerebral blood flow (CBF). In healthy controls (HCs), CBF is regulated complexly, and cardiac output (CO) is an important determinant of CBF. A review in HC showed that a 30% reduction in CO results in a 10% reduction in CBF. In contrast, we showed in ME/CFS patients with a normal HR (HR) and blood pressure response during a tilt test that CO and CBF decreased to a similar extent. The relation between CO and CBF in ME/CFS patients with postural orthostatic tachycardia syndrome (POTS) is unknown. Therefore, the aim of this study is to assess the relation between CBF and CO, in ME/CFS patients with POTS. The methods used in this retrospective study analyze this relation in a large group of patients. We also analyzed the influence of clinical data. A total of 260 ME/CFS patients with POTS underwent tilt testing with measurements of HR, BP, CBF, CO, and end-tidal PCO₂. We measured CBF using extracranial Doppler flow velocity and vessel diameters obtained with a General Electric echo system, and suprasternal aortic flow velocities were measured using the same device. We recorded end-tidal PCO₂ using a Nonin Lifesense device. Results: End-tilt HR and the HR increase were significantly higher in the patients with a %CO reduction ≥ −15% than in the other group. End-tilt CO was higher and the %CO reduction was lower in patients with %CO reduction ≥ −15% than in the other group. CBF data (supine, end-tilt and the %CBF reduction) were not different between the two patient groups. The use of HR increases and %SV reductions were not as discriminative as the %CO reduction. Conclusions: In ME/CFS patients with POTS during tilt testing with measurements of both the CO and the CBF, two different patterns were observed: (1) appr. two-thirds of patients had an almost 1:1 relation between the %CBF reduction and the %CO reduction. (2) Appr. one-third of patients showed a limited reduction in CO together with a substantial increase in HR. In these patients, there was no relation between the CO and CBF reduction. These data suggest the presence of a hyperadrenergic response. Full article

Automated ventilator controllers have the potential to simplify oxygen and carbon dioxide management for trauma. In the pre-hospital or military medicine environment, trauma care can be required for prolonged periods by personnel with limited ventilator management training. As such, there is a need for closed-loop control systems that can adapt ventilator management to a complex, ever-changing medical environment. Here, we present a novel hardware-in-loop test platform for the independent troubleshooting and evaluation of oxygen and carbon dioxide automated ventilator management capabilities. The oxygen management system provides an analogue blood oxygen signal that is responsive to the fraction of inspired oxygen and the peak inspiratory pressure ventilator settings. A tested oxygenation controller successfully reached the target oxygen saturation within 5 min. The carbon dioxide removal system integrates with commercial ventilator technology and mimics carbon dioxide generation, lung compliance, and airway resistance while providing an end-tidal carbon dioxide level that is responsive to changes in the tidal volume and respiratory rate settings. A test mechanical ventilator controller was able to regulate EtCO₂ regardless of the starting value within 10 min. This highlights the system’s functionality and provides proof-of-concept demonstrations for how the hardware-in-loop test platforms can be used for evaluating closed-loop controller technologies. Full article

Hemoglobin-based oxygen carriers (HBOCs) represent a promising alternative to traditional blood transfusions, offering the advantages of extended shelf life and avoiding blood compatibility limitations and infection risks. Positive effects of hemoglobin-based oxygen carriers (HBOCs) on hemorrhagic shock have been researched across various animal species, including swine, rats, rabbits, guinea pigs, and dogs. As previously described, HBOCs based on ovine hemoglobin display better efficiency in the context of hemorrhagic shock compared to those based on the more commonly used bovine hemoglobin. This was evidenced through higher survival rates and more favorable histopathological and immunological outcomes. The vascular effects of ovine hemoglobin polymerized with glutaraldehyde exposure included the absence of hypertension, minimal endothelial damage with slight alterations in inducible nitric oxide synthase (iNOS), and reduced vascular inflammation mediated by interleukin-10 (IL-10). Ovine hemoglobin has emerged as a particularly promising raw material for the development of HBOCs, surpassing bovine and human hemoglobin due to its advantages in availability and efficacy. Furthermore, reducing oxidative stress by polymerizing hemoglobin with glutaraldehyde is most effective with ovine hemoglobin compared to bovine hemoglobin. This study evaluates the effectiveness of ovine hemoglobin polymerized with glutaraldehyde in managing hemorrhagic shock in rabbits, with a focus on its ability to maintain blood pressure, support oxygen transport, and assess potential systemic and oxidative responses. Fifteen adult New Zealand white rabbits, divided into three equal groups, were included in this study: a negative control group transfused with colloid solutions, a positive control group treated with autotransfusion, and a group receiving HBOCs. All groups underwent a hemorrhagic shock protocol, with 40% of their total blood volume withdrawn under deep anesthesia, followed by transfusions 30 min later. Vital parameters, including invasive arterial blood pressure, heart rate, and end-tidal CO₂, were measured throughout the experimental procedures. Arterial blood gas samples were collected before the procedures, after hemorrhagic shock induction, and at the conclusion of the transfusion. In summary, HBOCs offer a promising solution for oxygen delivery, but their effects on blood chemistry, particularly CO₂ and lactate levels, must be considered. Although no direct oxygenation issues were observed in experimental models, elevated CO₂ levels and the interference of HBOCs with lactate measurements emphasize the importance of vigilant clinical monitoring. Polymerized hemoglobin provides a non-nephrotoxic alternative, but challenges persist in preventing nitric oxide scavenging and ensuring effective oxygen delivery. Full article

Formosan serows are an endemic species in Taiwan. Alfaxalone, a γ-aminobutyric acid_A agonist, induces or maintains anesthesia in various veterinary species with reported potential adverse effects of respiratory depression and tachycardia. α2-Adrenoceptor agonists exert sedative and muscle relaxation effects, along with substantial cardiovascular adverse effects. Here, we aimed to evaluate the anesthetic effects of alfaxalone combined with xylazine or dexmedetomidine (AX vs. AD, respectively) in Formosan serows. In this randomized, masked study, AX was administered to four serows, and AD was administered to five serows intramuscularly via blow dart. The time and score of induction and recovery were recorded. Post-intubation, isoflurane was administered for maintenance anesthesia. Heart rate (HR), respiratory rate (RR), peripheral saturation of oxygenation (SpO₂), rectal temperature (RT), and end-tidal CO₂ (EtCO₂) were recorded every five to eight minutes. Atipamezole and tolazoline were administered to antagonize dexmedetomidine and xylazine post-procedure, respectively. Both combinations allowed smooth induction and recovery. The AD group exhibited significantly lower HR and SpO₂ and significantly higher RT and EtCO₂ than the AX group (both p < 0.01). The AD-treated serows exhibited notable muscle rigidity after induction and significant hypoventilation and hypoxemia during the procedure. Although alfaxalone combined with dexmedetomidine or xylazine can produce satisfactory induction and recovery in Formosa serows, notable hypoxemia and hypoventilation are induced by the alfaxalone–dexmedetomidine combination compared to the alfaxalone–xylazine combination. Full article

Background: CPAP has been shown to be particularly beneficial in the management of acute cardiogenic pulmonary edema by reducing both preload and afterload, thus decreasing the work of breathing and improving oxygenation. Methods: This study was a prospective observational study, conducted in the period from 2022 to 2024, assessing the effectiveness and safety of prehospital CPAP therapy use in patients with acute cardiogenic pulmonary edema, administered alongside standard care. Results: In this study, 50 patients with acute cardiogenic pulmonary edema were treated by physician-led emergency teams in the Canton of Sarajevo. CPAP significantly improved clinical parameters across all time points. Systolic blood pressure decreased from 151.0 ± 41.0 mmHg at initial contact to 138.4 ± 32.0 mmHg before transportation and further to 130.2 ± 28.5 mmHg upon hospital admission (p < 0.001). Diastolic pressure dropped from 85.6 ± 17.2 mmHg to 81.1 ± 15.2 mmHg before transportation (p = 0.018), with a slight further decrease to 80.2 ± 13.9 mmHg (p = 0.083). Heart rate fell from 114 ± 26.4 bpm to 111.3 ± 24.9 bpm before transportation (p = 0.003) and finally to 99.5 ± 18.2 bpm before hospital admission (p < 0.001). Respiratory rate decreased from 31.0 ± 10.2 to 28.0 ± 10.5 breaths/min (p = 0.002) and further to 22.6 ± 7.3 breaths/min (p < 0.001). End-tidal CO₂ levels increased from 28.0 mmHg (23.5; 33.5) to 30.0 mmHg before transportation (p < 0.001), and to 35.0 mmHg (32.0; 37.5) before hospital admission (p < 0.001). Oxygen saturation improved from 79.0% (72.0; 81.0) to 84.0% before transportation (p < 0.001) and reached 94.0% (91.0; 98.2) before hospital admission (p < 0.001). VAS scores for dyspnea significantly dropped from 8.0 (6.0; 8.2) at initial contact to 6.0 (4.0; 8.0) before transportation (p < 0.001) and further to 4.0 (3.0; 5.0) before hospital admission (p < 0.001), indicating substantial symptom relief. ECG findings remained stable throughout the intervention. Conclusions: Prehospital CPAP therapy significantly improved clinical outcomes in cardiogenic pulmonary edema, including reductions in blood pressure, heart rate, respiratory rate, and enhanced oxygenation and symptom relief. These findings support its broader use in emergency care, even during short transport times. Full article

Introduction: Orthostatic intolerance is highly prevalent in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and is caused by an abnormal reduction in cerebral blood flow (CBF). In healthy controls (HCs), the regulation of CBF is complex and cardiac output (CO) is an important determinant of CBF: a review showed that a 30% reduction in CO results in a 10% reduction in CBF. In previous and separate ME/CFS studies, we showed that CO and CBF decreased to a similar extent during tilt testing. The aim of the study: to test the relationship between CBF and CO, which seems to be abnormal in ME/CFS patients and is different from that in HCs. Methods: In this retrospective study we analyzed this relationship in a large group of patients. To compare the patient data with those of HCs, we focused on patients with a normal heart rate (HR) and blood pressure (BP) response to upright tilt. Also, the influence of clinical data was analyzed. A total of 534 ME/CFS patients and 49 HCs underwent tilt testing with measurements of HR, BP, CBF, CO, and end-tidal PCO₂. To measure CBF, extracranial Doppler flow velocity and vessel diameters were obtained using a GE echo system. The same device was used to measure suprasternal aortic flow velocities. End-tidal PCO₂ was recorded using a Nonin Lifesense device. Results: In 46 (9%) patients, CO and CBF changes were in the normal range for HCs, and in 488 (91%) an abnormal CO and CBF reduction was found. In patients with abnormal CO and CBF reductions, the slope of the regression line of CO versus CBF reduction was almost 1. The multiple regression analysis of the latter group showed that the CO reduction for the most part predicted the CBF reduction, with a limited role for the P_ETCO₂ reduction. Conclusions: Two different patient groups with a normal HR and BP response during the tilt were identified: those with a CO and CBF in the normal range for HCs and those with an abnormal CO and CBF reduction during the tilt (91% of patients). In the latter group of patients, an almost 1:1 relationship between the CO and CBF reduction suggests the absence of compensatory vasodilation in the cerebral vasculature. This might indicate endothelial dysfunction in most ME/CFS patients and may have clinical and therapeutic implications. Full article

Background: Research into key performance factors in trail running, particularly in vertical kilometer (VK) races, is crucial for effective training and periodization. However, recent studies on metabolic and cardiorespiratory responses during VK races, especially using field tests, are limited. Objectives: Therefore, the aim of this study is to evaluate the metabolic and cardiorespiratory responses during a VK field test, identifying differences based on sex and performance level, as well as key performance factors and their deterioration due to fatigue. Fifteen trained trail runners (ten males and five females, 19 to 38 years old) perform a VK race. Methods: The global physiological response is evaluated using the portable gas analyzer Cosmed K5 and the local response using near-infrared spectroscopy technology. Results: In gender comparisons, the ANCOVA test shows significant differences (p < 0.05) in the ventilation, tidal volume, expiratory time-to-inspiratory time ratio, inspiratory flow rate, end-tidal CO₂ partial pressure, heart rate, oxygen pulse, and total hemoglobin. Additionally, the performance comparison reveals significant differences in the variables’ velocity, oxygen consumption, carbon dioxide production, ventilation, dead space-to-tidal volume ratio, total time of the breathing cycle, expiratory time-to-inspiratory time ratio, inspiratory duty cycle, expiratory fractions of CO₂, quadriceps saturation index, and VE/VCO₂ ratio. Finally, the correlation analysis shows oxygen consumption (r = −0.80 mean; r = −0.72 peak), carbon dioxide production (r = −0.91 mean; r = −0.75 peak), expiratory time-to-inspiratory time ratio (r = 0.68 peak), ventilation (r = −0.58 mean), and quadriceps saturation index (r = 0.54 mean; r = −0.76 coefficient of variation) as the key performance factors in the VK race. Conclusions: Overall, the physiological analysis indicates the importance of local muscular adaptations and respiratory system capacity in this type of short-duration race. Full article

The pacing of a marathon is arguably the most challenging aspect for runners, particularly in avoiding a sudden decline in speed, or what is colloquially termed a “wall”, occurring at approximately the 30 km mark. To gain further insight into the potential for optimizing self-paced marathon performance through the coding of comprehensive physiological data, this study investigates the complex physiological responses and pacing strategies during a marathon, with a focus on the application of Shannon entropy and principal component analysis (PCA) to quantify the variability and unpredictability of key cardiorespiratory measures. Nine recreational marathon runners were monitored throughout the marathon race, with continuous measurements of oxygen uptake ($\dot{\mathrm{V}}$O₂), carbon dioxide output ($\dot{\mathrm{V}}$CO₂), tidal volume (Vt), heart rate, respiratory frequency (Rf), and running speed. The PCA revealed that the entropy variance of $\dot{\mathrm{V}}$O₂, $\dot{\mathrm{V}}$CO₂, and Vt were captured along the F1 axis, while cadence and heart rate variances were primarily captured along the F2 axis. Notably, when distance and physiological responses were projected simultaneously on the PCA correlation circle, the first 26 km of the race were positioned on the same side of the F1 axis as the metabolic responses, whereas the final kilometers were distributed on the opposite side, indicating a shift in physiological state as fatigue set in. The separation of heart rate and cadence entropy variances from the metabolic parameters suggests that these responses are independent of distance, contrasting with the linear increase in heart rate and decrease in cadence typically observed. Additionally, Agglomerative Hierarchical Clustering further categorized runners’ physiological responses, revealing distinct clusters of entropy profiles. The analysis identified two to four classes of responses, representing different phases of the marathon for individual runners, with some clusters clearly distinguishing the beginning, middle, and end of the race. This variability emphasizes the personalized nature of physiological responses and pacing strategies, reinforcing the need for individualized approaches. These findings offer practical applications for optimizing pacing strategies, suggesting that real-time monitoring of entropy could enhance marathon performance by providing insights into a runner’s physiological state and helping to prevent the onset of hitting the wall. Full article

Background and Purpose: Early differentiation between acute ischaemic (AIS) and haemorrhagic stroke (ICH), based on cerebral and peripheral hemodynamic parameters, would be advantageous to allow for pre-hospital interventions. In this preliminary study, we explored the potential of multiple parameters, including dynamic cerebral autoregulation, for phenotyping and differentiating each stroke sub-type. Methods: Eighty patients were included with clinical stroke syndromes confirmed by computed tomography within 48 h of symptom onset. Continuous recordings of bilateral cerebral blood velocity (transcranial Doppler ultrasound), end-tidal CO₂ (capnography), electrocardiogram (ECG), and arterial blood pressure (ABP, Finometer) were used to derive 67 cerebral and peripheral parameters. Results: A total of 68 patients with AIS (mean age 66.8 ± SD 12.4 years) and 12 patients with ICH (67.8 ± 16.2 years) were included. The median ± SD NIHSS of the cohort was 5 ± 4.6. Statistically significant differences between AIS and ICH were observed for (i) an autoregulation index (ARI) that was higher in the unaffected hemisphere (UH) for ICH compared to AIS (5.9 ± 1.7 vs. 4.9 ± 1.8 p = 0.07); (ii) coherence function for both hemispheres in different frequency bands (AH, p < 0.01; UH p < 0.02); (iii) a baroreceptor sensitivity (BRS) for the low-frequency (LF) bands that was higher for AIS (6.7 ± 4.2 vs. 4.10 ± 2.13 ms/mmHg, p = 0.04) compared to ICH, and that the mean gain of the BRS in the LF range was higher in the AIS than in the ICH (5.8 ± 5.3 vs. 2.7 ± 1.8 ms/mmHg, p = 0.0005); (iv) Systolic and diastolic velocities of the affected hemisphere (AH) that were significantly higher in ICH than in AIS (82.5 ± 28.09 vs. 61.9 ± 18.9 cm/s), systolic velocity (p = 0.002), and diastolic velocity (p = 0.05). Conclusion: Further multivariate modelling might improve the ability of multiple parameters to discriminate between AIS and ICH and warrants future prospective studies of ultra-early classification (<4 h post symptom onset) of stroke sub-types. Full article

Purpose: Our aim was to use intracortical recording to enable the tracking of ischemic infarct development over the first few critical hours of ischemia with a high time resolution in pigs. We employed electrophysiological measurements to obtain quick feedback on neural function, which might be useful for screening, e.g., for the optimal dosage and timing of agents prior to further pre-clinical evaluation. Methods: Micro-electrode arrays containing 16 (animal 1) or 32 electrodes (animal 2–7) were implanted in the primary somatosensory cortex of seven female pigs, and continuous electrical stimulation was applied at 0.2 Hz to a cuff electrode implanted on the ulnar nerve. Ischemic stroke was induced after 30 min of baseline recording by injection of endothelin-1 onto the cortex adjacent to the micro-electrode array. Evoked responses were extracted over a moving window of 180 s and averaged across channels as a measure of cortical excitability. Results: Across the animals, the cortical excitability was significantly reduced in all seven 30 min segments following endothelin-1 injection, as compared to the 30 min preceding this intervention. This difference was not explained by changes in the anesthesia, ventilation, end-tidal CO₂, mean blood pressure, heart rate, blood oxygenation, or core temperature, which all remained stable throughout the experiment. Conclusions: The animal model may assist in maturing neuroprotective approaches by testing them in an accessible model of resemblance to human neural and cardiovascular physiology and body size. This would constitute an intermediate step for translating positive results from rodent studies into human application, by more efficiently enabling effective optimization prior to chronic pre-clinical studies in large animals. Full article

Oxidative stress (OS) is caused by an imbalance between the production of oxygen-containing free radicals and their elimination. General anesthesia increases the production of reactive oxygen species (ROS) and therefore causes oxidative stress. Our objective was to determine the effects of medetomidine–butorphanol (MEDBUT) and medetomidine–buprenorphine (MEDBUP) on oxidative stress and cardiorespiratory parameters in dogs undergoing ovariohysterectomy (OHE). Ten healthy female dogs were randomly assigned to two groups: the MEDBUT group (n = 5) received medetomidine and butorphanol, while the MEDBUP group (n = 5) received medetomidine and buprenorphine. OS was evaluated by measuring total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) during five different time points (from the administration of anesthetic drugs to 2 h after surgery). The observed vital cardiorespiratory parameters included heart rate (HR), respiratory rate (fR), noninvasive systolic (SAP) and diastolic (DAP) arterial blood pressures, oxygen saturation (SpO₂), end-tidal CO₂ (EtCO₂), and body temperature (BT). Cardiorespiratory parameters were altered at a significantly greater degree in animals sedated with MEDBUT (p < 0.05). The administration of medetomidine–butorphanol was more likely to increase OS parameters, while medetomidine–buprenorphine showed decreased levels of oxidative stress throughout the study. Full article

Prehospital care is a fundamental component of stroke care that predominantly focuses on shortening the time between diagnosis and reaching definitive stroke management. With growing evidence of the physiological parameters affecting long-term patient outcomes, prehospital clinicians need to consider the balance between rapid transfer and increased physiological-parameter monitoring and intervention. This systematic review explores the existing literature on prehospital physiological monitoring and intervention to modify these parameters in stroke patients. The systematic review was registered on PROSPERO (CRD42022308991) and conducted across four databases with citation cascading. Based on the identified inclusion and exclusion criteria, 19 studies were retained for this review. The studies were classified into two themes: physiological-monitoring intervention and pharmacological-therapy intervention. A total of 14 included studies explored prehospital physiological monitoring. Elevated blood pressure was associated with increased hematoma volume in intracerebral hemorrhage and, in some reports, with increased rates of early neurological deterioration and prehospital neurological deterioration. A reduction in prehospital heart rate variability was associated with unfavorable clinical outcomes. Further, five of the included records investigated the delivery of pharmacological therapy in the prehospital environment for patients presenting with acute stroke. BP-lowering interventions were successfully demonstrated through three trials; however, evidence of their benefit to clinical outcomes is limited. Two studies investigating the use of oxygen and magnesium sulfate as neuroprotective agents did not demonstrate an improvement in patient’s outcomes. This systematic review highlights the absence of continuous physiological parameter monitoring, investigates fundamental physiological parameters, and provides recommendations for future work, with the aim of improving stroke patient outcomes. Full article

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. Full article