Respiratory oscillations in alveolar oxygen tension measured in arterial blood

Formenti, Federico; Bommakanti, Nikhil; Chen, Rongsheng; Cronin, John N.; McPeak, Hanne; Holopherne-Doran, Delphine; Hedenstierna, Göran; Hahn, C.E.W.; Larsson, Anders; Farmery, Andrew D.

doi:10.1038/s41598-017-06975-6

Cited by 24 publications

(25 citation statements)

References 32 publications

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“…While our studies were performed in mice, there are respiration-driven fluctuations in the arterial blood of ungulates 61, 62 , suggesting it is a general property of mammals. While it is generally presumed that arterial blood is saturated in humans (but see 21 ), arterial oxygen tension decreases substantially with age 72 and acutely during sleep 73 .…”

Section: Discussionmentioning

confidence: 99%

“…One possible driver of the increases in cerebral oxygenation is the increase in respiration during locomotion. Changes in respiration affect blood oxygen levels in the carotid artery 61, 62 in anesthetized animals, and in humans, inhalation of 100% oxygen can elevate brain oxygen levels 63 . However, it is not known if normal fluctuations in respiration rate can impact cerebral oxygenation during normal behaviors.…”

Section: Locomotion Drives Vasodilation In Somatosensory But Not Fromentioning

confidence: 99%

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Cerebral oxygenation during locomotion is modulated by respiration

Zhang

Roche

Gheres

et al. 2019

Preprint

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25In the brain, increased neural activity is correlated with an increase of cerebral blood flow and 26 increased tissue oxygenation. However, how cerebral oxygen dynamics are controlled in the 27 behaving animals remains unclear. Here, we investigated to what extent the cerebral oxygenation 28 varies during natural behaviors that change the whole-body homeostasis, specifically exercise. 29We measured oxygen levels in the cortex of awake, head-fixed mice during locomotion using 30 polarography, spectroscopy, and two-photon phosphorescence lifetime measurements of oxygen 31 sensors. We found that locomotion significantly and globally increases cerebral oxygenation, 32 specifically in areas involved in locomotion, as well as in the frontal cortex and the olfactory bulb. 33The oxygenation increase persisted when neural activity and functional hyperemia were blocked, 34 occurred both in the tissue and in arteries feeding the brain, and was tightly correlated with 35 respiration rate and the phase of respiration cycle. Thus, respiration provides a dynamic pathway 36 for modulating cerebral oxygenation. 3An adequate oxygen supply is critical for proper brain function 1 , and deficiencies in tissue oxygen 38 is a noted comorbidity in human diseases 2 and aging 3 . For these reasons, there has been a great 39 deal of interest in studying dynamics of cerebral oxygenation [4][5][6][7][8][9] . However, there is a gap in our 40 understanding of how behavior, such as natural exercises like locomotion, affects cerebral 41 oxygenation. In natural environments, animals and humans have evolved to spend a substantial 42 portion of their waking hours locomoting 10 . As exercise is known to have a positive effect on brain 43 health 11,12 , a better understanding of the basic brain physiology accompanying the behaviors can 44 give insight into how exercise can improve brain function. During movement, neuromodulator 45 release and neural activity in many brain regions is elevated [13][14][15][16][17][18][19][20] , and there is an increase in 46 cardiac output and respiratory rate. How these changes in local and systemic factors interact to 47 control cerebral oxygenation is a fundamental question in brain physiology but is not well 48 understood. Most cerebral oxygenation studies are performed in anesthetized animals 8,9,[21][22][23] (but 49 see 4 ), or non-invasively in humans. Anesthesia causes large disruptions of brain metabolism and 50 neural activity 24 , and non-invasive human studies are impeded by technical issues, making 51 accurate determination of any aspect of brain tissue oxygenation problematic. 52Here we investigated how and by what mechanisms voluntary exercise impacts brain 53 tissue oxygenation. We used intrinsic optical signal imaging 13,25 , electrophysiology, Clark-type 54 polarography 5,6,23 , and two-photon phosphorescent dye measurement 4,8,9 to elucidate how 55 vasodilation, neural activity, and systemic factors combine to generate changes in brain 56 oxygenation. All experiments were performed in awake mice ...

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Section: Discussionmentioning

confidence: 99%

Section: Locomotion Drives Vasodilation In Somatosensory But Not Fromentioning

confidence: 99%

Cerebral oxygenation during locomotion is modulated by respiration

Zhang

Roche

Gheres

et al. 2019

Preprint

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“…Pulmonary perfusion can be affected by anesthesia and by mechanical ventilation, affecting arterial blood oxygenation [23][24][25][26][27]. The greatest determinant of pulmonary blood perfusion distribution is the difference between alveolar and pulmonary capillary pressures [28].…”

Section: Discussionmentioning

confidence: 99%

Real-time effects of PEEP and tidal volume on regional ventilation and perfusion in experimental lung injury

Borges

Cronin

Crockett

et al. 2020

ICMx

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Background: Real-time bedside information on regional ventilation and perfusion during mechanical ventilation (MV) may help to elucidate the physiological and pathophysiological effects of MV settings in healthy and injured lungs. We aimed to study the effects of positive end-expiratory pressure (PEEP) and tidal volume (V T ) on the distributions of regional ventilation and perfusion by electrical impedance tomography (EIT) in healthy and injured lungs. Methods: One-hit acute lung injury model was established in 6 piglets by repeated lung lavages (injured group). Four ventilated piglets served as the control group. A randomized sequence of any possible combination of three V T (7, 10, and 15 ml/kg) and four levels of PEEP (5, 8, 10, and 12 cmH 2 O) was performed in all animals. Ventilation and perfusion distributions were computed by EIT within three regionsof-interest (ROIs): nondependent, middle, dependent. A mixed design with one between-subjects factor (group: intervention or control), and two within-subjects factors (PEEP and V T ) was used, with a three-way mixed analysis of variance (ANOVA). Results: Two-way interactions between PEEP and group, and V T and group, were observed for the dependent ROI (p = 0.035 and 0.012, respectively), indicating that the increase in the dependent ROI ventilation was greater at higher PEEP and V T in the injured group than in the control group. A two-way interaction between PEEP and V T was observed for perfusion distribution in each ROI: nondependent (p = 0.030), middle (p = 0.006), and dependent (p = 0.001); no interaction was observed between injured and control groups. Conclusions: Large PEEP and V T levels were associated with greater pulmonary ventilation of the dependent lung region in experimental lung injury, whereas they affected pulmonary perfusion of all lung regions both in the control and in the experimental lung injury groups.

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“… 16 Measurements undertaken on the uninjured lungs of animals reported in this study have been published elsewhere. 10 …”

Section: Methodsmentioning

confidence: 99%

“…Moreover, oscillations in PaO 2 have been found in mechanically ventilated uninjured lungs with no tendency to collapse. 10 …”

mentioning

confidence: 99%

Tidal changes in PaO2 and their relationship to cyclical lung recruitment/derecruitment in a porcine lung injury model

Crockett

Cronin

Bommakanti

et al. 2019

British Journal of Anaesthesia

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BackgroundTidal recruitment/derecruitment (R/D) of collapsed regions in lung injury has been presumed to cause respiratory oscillations in the partial pressure of arterial oxygen (PaO2). These phenomena have not yet been studied simultaneously. We examined the relationship between R/D and PaO2 oscillations by contemporaneous measurement of lung-density changes and PaO2.MethodsFive anaesthetised pigs were studied after surfactant depletion via a saline-lavage model of R/D. The animals were ventilated with a mean fraction of inspired O2 (FiO2) of 0.7 and a tidal volume of 10 ml kg−1. Protocolised changes in pressure- and volume-controlled modes, inspiratory:expiratory ratio (I:E), and three types of breath-hold manoeuvres were undertaken. Lung collapse and PaO2 were recorded using dynamic computed tomography (dCT) and a rapid PaO2 sensor.ResultsDuring tidal ventilation, the expiratory lung collapse increased when I:E <1 [mean (standard deviation) lung collapse=15.7 (8.7)%; P<0.05], but the amplitude of respiratory PaO2 oscillations [2.2 (0.8) kPa] did not change during the respiratory cycle. The expected relationship between respiratory PaO2 oscillation amplitude and R/D was therefore not clear. Lung collapse increased during breath-hold manoeuvres at end-expiration and end-inspiration (14% vs 0.9–2.1%; P<0.0001). The mean change in PaO2 from beginning to end of breath-hold manoeuvres was significantly different with each type of breath-hold manoeuvre (P<0.0001).ConclusionsThis study in a porcine model of collapse-prone lungs did not demonstrate the expected association between PaO2 oscillation amplitude and the degree of recruitment/derecruitment. The results suggest that changes in pulmonary ventilation are not the sole determinant of changes in PaO2 during mechanical ventilation in lung injury.

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Respiratory oscillations in alveolar oxygen tension measured in arterial blood

Cited by 24 publications

References 32 publications

Cerebral oxygenation during locomotion is modulated by respiration

Cerebral oxygenation during locomotion is modulated by respiration

Real-time effects of PEEP and tidal volume on regional ventilation and perfusion in experimental lung injury

Tidal changes in PaO2 and their relationship to cyclical lung recruitment/derecruitment in a porcine lung injury model

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