The effect of high concentrations of inspired oxygen on middle cerebral artery blood velocity measured by transcranial Doppler

Bew, SA; Field, LM; Dw, Droste; Razis, Platon A

doi:10.1113/expphysiol.1994.sp003792

Cited by 15 publications

(9 citation statements)

References 10 publications

(14 reference statements)

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“…The fall in VIWM with hyperoxia in our study was 4 % (control protocol). This was in contrast to the results of both Ellingsen et al (1987), who found no fall in CBF when PET,02 was raised from 100 to 250 mmHg, and Bew et al (1994), who found no changes in CBF in response to inspired 02 concentrations of 21, 40, 75 and 100 %. However, the value was substantially below that of Purves (1972), who reported a fall in CBF of 11-14% upon inhalation of 85-100 % oxygen.…”

Section: Techniquescontrasting

confidence: 99%

Effects of 8h of eucapnic and poikilocapnic hypoxia on middle cerebral artery velocity and heart rate in humans

Clar

Pedersen²,

Poulin³

et al. 1997

Experimental Physiology

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SUMMARYThis study examines the effects of prolonged hypoxia, with and without control of end-tidal CO2 partial pressure (PET,CO2), on the intensity-weighted mean velocity of blood flow in the middle cerebral artery (VIwM) and on heart rate (HR). Specifically, the time course of the responses, their reversibility with brief periods of hyperoxia and the recovery phase following prolonged hypoxia were all investigated. Twelve subjects were studied, of whom nine provided satisfactory data. A purpose-built chamber was used for the prolonged control of the end-tidal gases, and an end-tidal forcing system was used for generating the brief variations in end-tidal gases. Three 16 h protocols were employed: (1) 8 h eucapnic (average PET,CO, 39 mmHg) hypoxia (end-tidal 02 partial pressure, PETO, = 55 mmHg) followed by 8 h eucapnic euoxia (PETO2 = 100 mmHg); (2) 8 h poikilocapnic (average PET,Co2 4 mmHg below eucapnia) hypoxia (PET,02 = 55 mmHg) followed by 8 h poikilocapnic euoxia (PET,O0 = 100 mmHg); and (3) control (air inspired throughout). VIwM (using Doppler ultrasound) and HR were measured during brief exposures to hypoxic/euoxic and hyperoxic conditions with PET,CO, held 1-2 mmHg above eucapnia, at 0, 20, 240 and 480 min in the first 8 h, and at the same times in the second 8 h. There were no significant trends in VIWM under hypoxic conditions for either hypoxic protocol (ANOVA) and no significant differences between the three protocols for VIwM in hyperoxia (ANOVA). In contrast to VIWM, there was a significant increase in HR over time during both hypoxic exposures (P < 0.01, ANOVA). HR increased to a similar extent for the two types of hypoxia, and there was some suggestion that HR remained elevated after the relief of hypoxia. The results suggest that, with the level of hypoxia employed, progressive changes in HR occur, but that this level and duration of hypoxia has little sustained effect on VIWM.

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Section: Techniquescontrasting

confidence: 99%

Effects of 8h of eucapnic and poikilocapnic hypoxia on middle cerebral artery velocity and heart rate in humans

Clar

Pedersen²,

Poulin³

et al. 1997

Experimental Physiology

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“…The raw power and P episode values were averaged across all participants and across all electrodes to demonstrate the gross differences between the four conditions. Examining eyesclosed and eyes-opened trials separately, we performed a cluster-based statistical analysis of the effect of hyperoxia across frequencies and electrodes (Bew, Field, Droste, & Razis, 1994;Desai, Tailor, & Bhatt, 2015;Kety & Schmidt, 1948;Pack, Cola, Goldszmidt, Ogilvie, & Gottschalk, 1992;Tsanov, Chah, Reilly, & O'Mara, 2014). The effect of hyperoxia was assessed at every electrode and every sampled frequency by a two-tailed uncorrected paired t-test with an alpha set to 0.05.…”

Section: Time Frequency Analysismentioning

confidence: 99%

“…Previous work has shown that hyperoxia induces changes in basic physiological parameters such as breathing and heart rate and in turn, these changes may directly or indirectly affect brain state or function Colrain et al, 1987;Desai et al, 2015;Pack et al, 1992;Tsanov et al 2014;Yackle et al, 2017). Indeed, hyperoxia is also known to induce changes in cerebral blood flow (Bergo and Tyssebotn 1995;Bew et al, 1994;Busija et al, 1980;Floyd et al, 2003; HYPEROXIA ON BRAIN ACTIVITY 4 Kety and Schmidt, 1948;Lund et al, 1999;Watson et al, 2000), which might also be expected to result in a functional change in the operation of the brain even given the fact that cerebral blood flow and brain state can show independence from each other, despite their typical tight correspondence (Bangash et al 2008;Braun et al 1997;Hajak et al 1994;Hofle et al 1997). In terms of pathological influences, there are also deleterious consequences of hyperoxia due to the production of reactive oxidative species (ROS), however, the exposure times necessary to observe these effects are quite long (~ 6 hours in normobaric conditions).…”

Section: Introductionmentioning

confidence: 99%

Electrophysiological correlates of hyperoxia during resting-state EEG in awake human subjects

Vuong

Kizuk

MacLean

et al. 2018

Preprint

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Recreational use of concentrated oxygen has increased. Claims have been made that hyperoxic breathing can help reduce fatigue, increase alertness, and improve attentional capacities; however, few systematic studies of these potential benefits exist. Here we examined the effects of short-term (15 minute) hyperoxia on resting-states in awake human subjects by measuring spontaneous EEG activity between normoxic and hyperoxic situations, using a within-subjects design for both eyes-opened and eyes-closed conditions. We also measured respiration rate, heart rate, and blood oxygen saturation levels to correlate basic physiological changes due to the hyperoxic challenge with any brain activity changes. Our results show that breathing short term 100% oxygen led to increased blood-oxygen saturation levels, decreased heart rate, and a slight, but non-significant, decrease in breathing rate. Changes of brain activity were apparent, including decreases in low-alpha (7-10 Hz), high-alpha (10-14 Hz), beta (14-30 Hz), and gamma (30-50 Hz) frequency ranges during eyes-opened hyperoxic conditions. During eyes-closed hyperoxia, increases in the delta (0.5-3.5 Hz) and theta (3.5-7 Hz) frequency range were apparent together with decreases in the beta range. Hyperoxia appeared to accentuate the decrease of low alpha and gamma ranges across the eyes-opened and closed conditions suggesting that it modulated brain state itself. As decreased alpha during eyes-opened conditions has been associated with increased attentional processing and selective attention, and increased delta and theta during eyes-closed condition are typically associated with the initiation of sleep, our results suggest a state-specific and perhaps opposing influence of short-term hyperoxia.

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“…Raising alveolar Pcoz (PAco,) by breathing a C02-rich gas mixture dilates the cerebral vessels and increases blood flow, while lowering PACO~ by hyperventilation causes vasoconstriction and may endanger the oxygen supply [ l , 21. A reduced arterial oxygen content increases cerebral blood flow [3], but breathing 100% oxygen does not reduce cerebral perfusion [4].…”

Section: Introductionmentioning

confidence: 99%

Cerebral Blood Flow Velocity during and after Sustained Isometric Skeletal Muscle Contractions in Man

Imms¹,

Russo

Iyawe³

et al. 1998

Clinical Science

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1. Twenty-seven young subjects used their right hand to perform sustained, isometric contractions at 40% of maximum for 2 min while lying supine. 2. During the last 30 s of exercise, mean arterial blood pressure increased by 38 +/- 4 mmHg (mean +/- S.E.M.) and heart rate by 27 +/- 2 beats/min. 3. Nineteen of the subjects respired eucapnically during exercise, increasing ventilation by 4.1 +/- 0.5 litres/min. Eight subjects hyperventilated (7.1-19.6 litres/min) and decreased end-tidal PCO2 by 8.2 to 15.1 mmHg during the last minute of exercise. 4. In the eucapnic subjects mean flow velocity in the right (i.e. contralateral to the activated cortex) middle cerebral artery increased by 11.4 +/- 1.0 cm/s, a change of 17%, during the contraction. This represents an increase in volume flow to the territory of this vessel, but an increase in global flow to the brain cannot be inferred. 5. In the eight subjects who hyperventilated during exercise, there was no rise of flow velocity in the middle cerebral artery, and in some subjects there was a fall during the first 2 min of recovery. These findings suggest that if subjects hyperventilate during handgrip exercise there could be a fall in volume flow to many regions of the brain during and after the exercise.

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The effect of high concentrations of inspired oxygen on middle cerebral artery blood velocity measured by transcranial Doppler

Cited by 15 publications

References 10 publications

Effects of 8h of eucapnic and poikilocapnic hypoxia on middle cerebral artery velocity and heart rate in humans

Effects of 8h of eucapnic and poikilocapnic hypoxia on middle cerebral artery velocity and heart rate in humans

Electrophysiological correlates of hyperoxia during resting-state EEG in awake human subjects

Cerebral Blood Flow Velocity during and after Sustained Isometric Skeletal Muscle Contractions in Man

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