Respiratory Physiology & Neurobiology最新文献

{"title":"Breath-hold diving as a tool to harness a beneficial increase in cardiac vagal tone","authors":"Pierrick Martinez ,&nbsp;Mathias Dutschmann ,&nbsp;Vincent Epercieux ,&nbsp;Géraud Gourjon ,&nbsp;Fabrice Joulia","doi":"10.1016/j.resp.2025.104416","DOIUrl":"10.1016/j.resp.2025.104416","url":null,"abstract":"<div><div>Here we review central mechanisms that mediate the diving bradycardia and propose that breath-hold diving (BH-D) is a powerful therapeutic tool to improve cardiac vagal tone (CVT). Physiological fluctuations in CVT are known as the respiratory heart rate variability (respirHRV) and involve two respiratory-related brainstem mechanisms. During inspiration pre-Bötzinger complex (pre-BötC) neurons inhibit cardiac vagal motor neurons to increase heart rate and subsequently cardiac vagal disinhibition and a decrease in heart rate is associated with a Kölliker-Fuse (KF) nucleus-mediated partial glottal constriction during early expiration. Both KF and pre-BötC receive direct descending cortical inputs that could mediate volitional glottal closure as critical anatomical framework to volitionally target brainstem circuits that generate CVT during BH-D. Accordingly we show that volitional and reflex glottal closure during BH-D appropriates the respirHRV core network to mediate the diving bradycardia via converging trigeminal afferents inputs from the nose and forehead. Additional sensory inputs linked to prolonged BH-D after regular training further increase CVT during the acute dive and can yield a long-term increase in CVT. Centrally, evidence of Hebbian plasticity within respirHRV/BH-D core circuit further support the notion that regular BH-D exercise can yield a permanent increase in CVT specifically via a sensitization of synapse involved in the generation of the respirHRV. Contrary to other regular physical activity, BH-D reportedly does not cause structural remodeling of the heart and therefore we suggest that regular BH-D exercise could be employed as a save and non-invasive approach to treat sympathetic hyperactivity, particularly in elderly patients with cardio-vascular predispositions.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"334 ","pages":"Article 104416"},"PeriodicalIF":1.9,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143650127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Altered breathing pattern of lowlanders sleeping at high altitude: Novel insights from home sleep apnoea tests procedures","authors":"Pierpaolo Prosperi ,&nbsp;Antonella Spacone ,&nbsp;Alberto Taverna ,&nbsp;Riccardo Rua ,&nbsp;Sofia Bonan ,&nbsp;Giorgia Rapacchiale ,&nbsp;Danilo Bondi ,&nbsp;Camillo Di Giulio ,&nbsp;Giuseppe Miserocchi ,&nbsp;Vittore Verratti","doi":"10.1016/j.resp.2025.104415","DOIUrl":"10.1016/j.resp.2025.104415","url":null,"abstract":"<div><div>Lowlanders sojourning at high altitude often experience sleep disturbances, which are driven by blood gases alterations and manifest as stress-related patterns, including frequent awakenings, apnoeas, reduction in sleep duration and possibly with the occurrence of periodic breathing. This study demonstrated clinical evidence of sleep disturbances at high altitude by using portable device during a Himalayan expedition. The home sleep apnoea test was conducted on 10 participants taking part in the \"Lobuche Peak - Pyramid Exploration &amp; Physiology\". The longitudinal design included five assessments, before the expedition, at pre-expedition at Kathmandu (≈1400 m), at a peak altitude of ≈ 5000 m, upon return to Kathmandu and one month after return in Italy. Total sleep time was below 7 h of duration at the highest altitude in all participants. Nocturnal SpO₂ dropped below daytime measurement and was greatly reduced at high altitude; conversely, heart rate increased. All participants experienced an increase in apnea-hypopnea index at high altitude, with seven out of 10 falling in moderate-to-severe grade. Periodic breathing pattern was clearly observed in two participants, of whom one developed acute mountain sickness and one did not. All the impairments were fully reversible once back at low altitude. Translationally, our findings underscore the importance of conducting home sleep apnoea tests at living altitude. Sleep-disordered breathing arises from a complex pattern that can be due to a wide range of responses, and the overall functions revealed by home sleep apnoea testing during a field expedition have the potential to increase the safety of high altitude sojourners, while advancing our knowledge of hypoxia as the red line linking respiratory and environmental physiology.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"334 ","pages":"Article 104415"},"PeriodicalIF":1.9,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143586653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bulk and regional diaphragm blood flow during chemical hyperpnea in pulmonary hypertensive rats","authors":"Kiana M. Schulze ,&nbsp;Andrew G. Horn ,&nbsp;Ramona E. Weber ,&nbsp;K. Sue Hageman ,&nbsp;Britton C. Scheuermann ,&nbsp;Carl J. Ade ,&nbsp;Bradley J. Behnke ,&nbsp;David C. Poole ,&nbsp;Timothy I. Musch","doi":"10.1016/j.resp.2025.104414","DOIUrl":"10.1016/j.resp.2025.104414","url":null,"abstract":"<div><div>Pulmonary hypertension (PH) is a disease characterized by increased pulmonary arterial pressures, impaired gas exchange, dyspnea, and diaphragmatic dysfunction. Specifically, in PH, the diaphragm displays impaired contractility, vascular dysfunction, and blood flow redistribution toward less mechanically advantageous regions such as the ventral costal and crural diaphragm at rest and during submaximal exercise. While diaphragm blood flow is not a limitation to maximal exercise in health, whether it limits diaphragm function in PH is unknown. We hypothesized that, during chemically induced hyperpnea: 1) diaphragm blood flow will be lower in rats with PH compared with healthy controls due to vasodilatory impairments in the diaphragm vasculature, and 2) in PH, blood flow will be redistributed toward less mechanically advantageous regions of the diaphragm. Female Sprague-Dawley rats were randomized into healthy (n = 12) or monocrotaline-induced PH (n = 12) groups. Fluorescent microspheres were used to determine bulk and regional diaphragm blood flow at rest and during hypoxic-hypercapnic gas inhalation (10 % O₂-8 % CO₂). During chemically induced hyperpnea, diaphragm blood flow was higher in PH compared with healthy controls (483 ± 102 vs. 298 ± 119 ml/min/100 g; P &lt; 0.001), and the ventral costal and crural regions of the diaphragm supported greater perfusion in PH. These results are consistent with previous findings at rest and during submaximal exercise in PH, which may help explain diaphragmatic weakness and dyspnea across a range of ventilatory demands in PH.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"335 ","pages":"Article 104414"},"PeriodicalIF":1.9,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143458975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Breathing pattern and ventilatory response to exercise in patients with Chronic Obstructive Pulmonary Disease","authors":"Rocco Accogli ,&nbsp;Annalisa Frizzelli ,&nbsp;Olha Bondarenko ,&nbsp;Panagiota Tzani ,&nbsp;Luigino Calzetta ,&nbsp;Alessandra Marchese ,&nbsp;Roberta Pisi ,&nbsp;Gaetano Caramori ,&nbsp;Alfredo Chetta ,&nbsp;Marina Aiello","doi":"10.1016/j.resp.2025.104413","DOIUrl":"10.1016/j.resp.2025.104413","url":null,"abstract":"<div><h3>Background</h3><div>Patients with Chronic Obstructive Pulmonary Disease (COPD) show ventilatory limitation to exercise due to dynamic hyperinflation (DH). Breathing pattern can be expressed by T_I/T_TOT (inspiratory time/total time) and V_T/T_I (tidal volume/inspiratory time). Both parameters significantly increase during exertional hyperpnea in healthy subjects, but they have never been studied in COPD. In a large cohort of COPD patients, we analysed T_I/T_TOT and V_T/T_I at rest and during maximal exercise.</div></div><div><h3>Methods</h3><div>We enrolled clinically stable COPD patients with wide degree of airflow obstruction. All participants underwent spirometry and cardiopulmonary exercise testing (CPET) on a cycle ergometer.</div></div><div><h3>Results</h3><div>In 234 COPD patients (75 females; age range 41–89 years), T_I/T_TOT and V_T/T_I values significantly increased during exercise, from 0.259 ± 0.040–0.304 ± 0.038 and from 854.1 ± 229,6 ml/s to 2100 ± 622.5 ml/s respectively (p &lt; 0.05). T_I/T_{TOT peak} and V_T/T_{I peak} were positively related (p &lt; 0.05) with VO_2peak (ml/min/kg), maximal workload (Watt). T_I/T_{TOT peak}, but not V_T/T_{I peak} values showed a positive correlation (p &lt; 0.05) with the peak-rest difference of inspiratory capacity (ΔIC, in ml). When related to minute ventilation T_I/T_TOT and V_T/T_I rest values in patients with DH (ΔIC ≥150 ml), compared with those without DH, did not differ between the two groups, though T_I/T_TOT, but not V_T/T_I values, significantly increased during exercise in patients without DH</div></div><div><h3>Conclusions</h3><div>T_I/T_TOT and V_T/T_I values significantly increase during maximal exercise in COPD. T_I/T_TOT values were significantly correlated with dynamic hyperinflation. Our results suggest that T_I/T_TOT and V_T/T_I assessment may provide further information on exercise ventilatory limitation in COPD.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"335 ","pages":"Article 104413"},"PeriodicalIF":1.9,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143458969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of gas exchange surface area from DLNO and DLCO","authors":"Colin Borland","doi":"10.1016/j.resp.2025.104403","DOIUrl":"10.1016/j.resp.2025.104403","url":null,"abstract":"<div><div>The estimated diffusion coefficients for nitric oxide and carbon monoxide in human plasma and red cells can be inserted into the equations for Fick’s 1st and 2nd laws. The surface area of the alveolar membrane and exposed red cells can then be calculated from D_LNO and D_LCO (in hyperoxia). This yields a value of 18.7 m² for alveolar capillary membrane via D_LNO, 19.6 m² for red cell surface area via D_LCO in a seated human at rest and = 2.03m² for a membrane oxygenator. The values for a seated human are substantially less than morphometric values. This is likely due to a considerable functional reserve in the lung.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"335 ","pages":"Article 104403"},"PeriodicalIF":1.9,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143426062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modulating respiratory mechanics and inflammation in hepatopulmonary syndrome: Aerobic exercise as a therapeutic strategy","authors":"César Augusto Melo-Silva ,&nbsp;Walter Moreno Campos Nunes ,&nbsp;Eloisa Sanches Pereira Nascimento ,&nbsp;Eduardo Marques Guerra ,&nbsp;Marcello Rodrigues Roza ,&nbsp;Suellen Silva-Costa ,&nbsp;Wilcelly Machado-Silva ,&nbsp;Gleiciane Gontijo Avelar ,&nbsp;Otávio Toledo Nóbrega ,&nbsp;Veronica Moreira Amado","doi":"10.1016/j.resp.2025.104410","DOIUrl":"10.1016/j.resp.2025.104410","url":null,"abstract":"<div><h3>Introduction</h3><div>Aerobic exercise training positively modulates the immune system and improves lung function; however, its effects on respiratory system’s elastic, resistive properties and interleukin-10 (IL-10) concentration in hepatopulmonary syndrome (HPS) remains unexplored. This study aimed to assess whether moderate-intensity aerobic (AE) training altered exercise capacity, respiratory mechanics and lung inflammation.</div></div><div><h3>Material and methods</h3><div>Wistar rats were randomly assigned to SHAM, HPS, HPS + AE4, and HPS + EA8 groups. The EA4 group represents AE training for 4 weeks starting 7 days after HPS induction, whereas EA8 accounts for AE training for 4 weeks before and after HPS induction, both protocols practiced 3 times weekly. Exercise capacity, respiratory mechanics, lung and systemic inflammation, and lung morphology were assessed.</div></div><div><h3>Results</h3><div>Moderate aerobic exercise significantly increased the maximal running capacity of the HPS animals. The training decreased tissue elastance by 19 % (p = 0.01 compared to SHAM) and reduced frequency-dependent respiratory reactance at 0.5 Hz, 0.75 Hz, and 1.25 Hz frequencies compared to HPS animals (p &lt; 0.05 for all). For the HPS + EA4 and HPS + EA8 groups IL-10 plasma concentration increased by 23 % and 31 % compared to SHAM (p &lt; 0.001 both) and by 38 % and 47 % compared to HPS (p &lt; 0.01 both). Nonetheless, AE did not alleviate lung tissue remodeling induced by HPS.</div></div><div><h3>Conclusions</h3><div>Moderate-intensity aerobic training improved maximum running capacity, reduced HPS-induced respiratory mechanics derangements at the lung regional level, and increased systemic IL-10 concentration, although it did not ameliorate lung tissue remodeling.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"335 ","pages":"Article 104410"},"PeriodicalIF":1.9,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Muscle oxygenation and local blood volume difference between intercostal and deltoid during dry static apnea in breath-hold divers","authors":"Dario Vrdoljak ,&nbsp;Željko Dujić ,&nbsp;Colin D. Hubbard ,&nbsp;Geoff B. Coombs ,&nbsp;Andrew T. Lovering ,&nbsp;Ivan Drvis ,&nbsp;Nikola Foretic ,&nbsp;Joseph W. Duke","doi":"10.1016/j.resp.2025.104402","DOIUrl":"10.1016/j.resp.2025.104402","url":null,"abstract":"<div><div>During either a static or dynamic apnea, oxygen is delivered to vital organs, i.e., the brain and heart, and there is a compensatory reduction of oxygen consumption in peripheral tissues. Additionally, maximal apnea is characterised by the initial easy-going phase and subsequent struggle phase in which involuntary breathing movements appear. The aim of this study was to compare the oxygenation and local blood volume of one active (external intercostal) and one non-active (deltoid) muscle during maximal dry static apneas in breath-hold divers while supine. Thirteen breath-hold divers performed 3 preparatory apneas followed by 3 maximal apneas with 5 min of supine rest between each apnea. During all apneas (duration, 115–323 s; IBM, 7–35) muscle oxygenation and muscle blood volume change were measured via NIRS. The variables quantified were muscle oxygen saturation (SmO₂) and total hemoglobin (tHb). We found that the decline in oxygen saturation was similar in external intercostals and deltoids, even though their physiological role during a breath-hold is different. However, the external intercostals re-saturated at a significantly higher rate following a maximal apnea than the deltoid muscle (p = 0.02). Also, during the apneas, there was a significantly different response between muscles, where external intercostals had an increase and deltoid a decrease in tHb (p = 0.01). These findings indicate that despite respiratory muscle activity resulting from IBMs during breath-holds external intercostal muscle re-oxygenation occurs faster than peripheral muscles which may allow for a faster return to normal breathing.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"335 ","pages":"Article 104402"},"PeriodicalIF":1.9,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143374564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phrenic motor output following acute hyperbaric oxygen exposure","authors":"Prajwal P. Thakre ,&nbsp;Kyle M. Deegan ,&nbsp;David D. Fuller","doi":"10.1016/j.resp.2025.104399","DOIUrl":"10.1016/j.resp.2025.104399","url":null,"abstract":"<div><div>We studied adult male rats to determine if phrenic motor output is altered following acute hyperbaric oxygen (HBO) pretreatment. Rats were treated with 1-h of 100 % O₂ at 2 atmospheres (HBO, n = 12) or 21 % O₂ at 1 atmosphere (normoxia, n = 12) and then anesthetized and ventilated to enable phrenic nerve recordings. Baseline phrenic output and blood pressure were similar between groups. Sixty minutes after exposure to acute intermittent hypoxia (AIH), inspiratory phrenic burst amplitude was +66 ± 47 (HBO) and +43 ± 13 % baseline (normoxia). Thus, both groups expressed phrenic long-term facilitation, pLTF (time effect, P = 0.008). The pLTF magnitude had a larger coefficient of variation after HBO (71 %) <em>vs</em>. normoxia (30 %). This resulted from a bimodal data distribution, with 4 of 12 HBO rats showing pLTF &gt; +70 % baseline (<em>vs.</em> 0 of 12 normoxia). We conclude that acute HBO does not impact baseline phrenic output in this preparation, but further study of HBO and phrenic neuroplasticity is warranted.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"335 ","pages":"Article 104399"},"PeriodicalIF":1.9,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143374521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of ambient temperature on dexmedetomidine-induced metabolic and cardiorespiratory suppression in spontaneously breathing newborn rats","authors":"Eishi Nakamura,&nbsp;Nana Sato Hashizume,&nbsp;Hinata Kubota,&nbsp;Ryoji Ide,&nbsp;Chikako Saiki","doi":"10.1016/j.resp.2025.104401","DOIUrl":"10.1016/j.resp.2025.104401","url":null,"abstract":"<div><div>Newborn animals are known to increase the ventilation–metabolism ratios in hypoxia, particularly at cold environment by decreasing the thermogenesis. We examined whether ambient temperatures and thermoregulatory suppression due to dexmedetomidine, an α₂ adrenoceptor agonist, affect the coupling between ventilation and metabolism in neonatal rats. Wistar rats (3–7 days old) were measured for metabolic and cardiorespiratory indices. Control recordings were made at 34 °C ambient temperature (Ta) and Ta was either kept at 34 °C (Medium), reduced to 27 °C (Low) or increased to 39 °C (High). Once at the desired Ta, the rats were administered normal saline or dexmedetomidine (50 μg∙kg⁻¹) and the indices were again recorded. Control values were comparable between the normal saline and dexmedetomidine groups. Using values relative to the control values in each group, body temperature (Low or High vs. Medium Ta) and heart rate (Low vs. High Ta) were significantly different among the three Ta. At each Ta, the dexmedetomidine group showed significantly lower metabolic rates, minute ventilation, respiratory rate and heart rate, compared to the normal saline group. Despite these changes, the ventilation<img>metabolism ratios in the dexmedetomidine group were comparable at the Medium and Low Ta, and significantly lower at the High Ta, compared to the normal saline group. Dexmedetomidine plus atipamezole (5 mg∙kg⁻¹, an α₂ adrenoceptor antagonist) did not affect the ventilation–metabolism ratios at the Low and High Ta. Although dexmedetomidine suppresses thermoregulatory responses, the coupling of ventilation and metabolic rates can be preserved through α₂ adrenoceptor activation at cold, but not at hot, ambient temperature. Our results suggest that α₂ adrenoceptor activation impairs control of ventilation at heating or rewarming in newborn rats.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"335 ","pages":"Article 104401"},"PeriodicalIF":1.9,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling the distribution of the oxygen-haemoglobin dissociation curve in vivo: An observational study","authors":"Colin J. Crooks ,&nbsp;Joe West ,&nbsp;Joanne R. Morling ,&nbsp;Mark Simmonds ,&nbsp;Irene Juurlink ,&nbsp;Steve Briggs ,&nbsp;Simon Cruickshank ,&nbsp;Susan Hammond-Pears ,&nbsp;Dominick Shaw ,&nbsp;Timothy R. Card ,&nbsp;Andrew W. Fogarty","doi":"10.1016/j.resp.2025.104400","DOIUrl":"10.1016/j.resp.2025.104400","url":null,"abstract":"<div><div>Few studies have explored the variability of the oxygen-haemoglobin dissociation curve <em>in vivo</em>.</div><div>96,428 blood gas measurements were obtained (80,376 arterial, 6959 venous) from a cohort of 7656 patients who were admitted to a large UK teaching hospital between 1 February 2020 and 31 December 2021 for a Covid-19 related admission with a positive PCR. There was consistent variation of the distribution of the oxygen-haemoglobin curve across most oxygen saturation strata with typical values at 91–92 % saturation (mean 8.1kPa, standard deviation sd 0.6 kPa or 60.8 mmHg sd 4.5 mmHg), with the exception of the highest strata of oxygen saturation of 99–100 % (mean 17.7 kPa, sd 8.1kPa or 132 mmHg sd 60.8).</div><div>The higher oxygen partial pressures at higher oxygen saturations are a concern in view of the increased mortality observed in RCTs of higher oxygen saturation targets. However, the observational study design precludes any attribution of causality.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"333 ","pages":"Article 104400"},"PeriodicalIF":1.9,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143171404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}