Fluctuations of arterial oxygen tension which have the same period as respiration

Purves, M. J.

doi:10.1016/0034-5687(66)90047-8

Cited by 85 publications

(38 citation statements)

References 20 publications

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“…In adults, response was fastest in nonkeratinized areas (lip) and slowest in areas with thickest epidermis (palm). These observations appear to be consistant with those of Purvis (19) who found that thick membranes used in making Po2 electrodes lengthened response time.…”

Section: In Vivo Responsesupporting

confidence: 83%

“…In studies of newborn animals, Pao2 has been observed to fall at a rate of 2 to 3 torr/sec after airway obstruction (14). In other animal studies, using an intravascular electrode with extremely rapid response (95% response, 0.3 sec), Purves (19) noted similar rates of change in Paoz after step change in inspired oxygen tension or spontaneous deep breaths. Considering the present RT determinations, we conclude that significant divergence of P a o n from t.c.…”

Section: In Vivo Responsementioning

confidence: 92%

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Evaluation of Response Time of a Transcutaneous Oxygen Tension Electrode

1981

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SummaryResponse characteristics of a transcutaneous Po2 electrode to step changes in Pao2 were determined. In v i m lag time and 95% response time of a transcutaneous PO2 monitor were compared to in vivo response. Release of arterial occlusion was used to produce rapid local Pa02 changes in human infants and adults. I n vitm lag time and 95% response time varied according to whether an increment or decrement in Po2 was produced. I n vivo 95% response time of this electrode was two to six times slower than previous estimates, and it varied significantly with the magnitude of the step change, subject age, anatomic location, and local hemodynamic factors. Also, we found that in vivo lag time is two to three times faster than previously reported. SpeculationUnder steady-state conditions, transcutaneous Po2 correlates well with Pao2, but when rapid change is encountered as during oxygen administration or apnea, transcutaneous Po2 will significantly underestimate Pa02 change. On the other hand, the relatively short lag time suggests that the transcutaneous Po2 electrode may be useful in following rapid Pa02 changes qualitatively.Monitoring transcutaneous oxygen tension (t.c. Poz) is a recent but already widely used technique in the care of sick infants. Under steady state conditions, t.c. Po2 has been shown to correlate well with arterial oxygen tension (Pao2) (10, 11,22). Recently, investigators have begun to use this instrument to evaluate rapid changes in Pa02 (1, 2, 17, 18); however, the usefulness of this technique for estimating Pa02 in nonsteady state situations is unknown. We have determined the responsiveness of a t.c. Po2 electrode to arterial Poz change and have compared the in vivo lag and response times to in vitro response. We have observed that the in vivo response of this electrode is slower than previous estimates; moreover, the response time is influenced by magnitude of step change, subject age, anatomic location, and local hemodynamic factors. METHODS AND SUBJECTS IN VIVO STUDIESVascular occlusion was used to produce step changes in dermal capillary Po2 (5-9). Arterial occlusion was achieved by inflating a blood pressure cuff 20 to 30 mm Hg above the systolic pressure, after which there was a gradual fall in t.c. Poz. The duration of arterial occlusion was varied to change the magnitude of Po2 reduction. After sudden deflation of the cuff, t.c. Po2 increased gradually (Fig. I). The t.c. Poz, heat flux of the electrode, and the pneumatic cuff pressure were recorded on a Beckman R611 LAG TIMEWe defined the lag time (LT) as the time required for t.c. Po2 to begin to rise after the release of arterial occlusion (Fig. I). RESPONSE TIMEThe difference between the lowest t.c. POZ value produced by arterial occlusion and the steady-state t.c. Poz of the pre-and postarterial occlusion was termed the step change in Po2 (A t.c. Po2). The time interval after the release of arterial occlusion required for the electrode to register 95% of the step change in t.c. Poz was termed the 95% response time (95% RT) (Fig....

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Section: In Vivo Responsesupporting

confidence: 83%

Section: In Vivo Responsementioning

confidence: 92%

Evaluation of Response Time of a Transcutaneous Oxygen Tension Electrode

1981

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“…Furthermore, when brain movement did occur the fluctuations in PO-were often out of phase with the movement. We 196 think it is possible that some of the fluctuations reflect respiratory variation in arterial PO-_» as found by Purves 8 in the carotid artery, but much more experimentation will be required before real evidence is forthcoming.…”

Section: O 400mentioning

confidence: 94%

“…Tests of the electrode indicate that it is capable of measuring oxygen tension in tissues. 8 Occasionally a largertipped electrode (30/i,) was used for comparison. This electrode had a slower response time, but otherwise gave similar results ( fig.…”

Section: /Methodsmentioning

confidence: 99%

Effects of Breathing O ₂ or O ₂ + CO ₂ and of the Injection of Neurohumors on the PO ₂ of Cat Cerebral Cortex

Whalen

Ganfield

Nair

1970

Stroke

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Effects of Breathing Oi or O, + CO, and of the Injection of Neurohumors on the PO, of Cat Cerebral Cortex• Tissue PO 2 was measured in the outer 1.7 mm of the brain of the lightly anesthetized cat by means of a micro O 2 electrode introduced through a small hole in the skull. There was considerable variation from one location to another and from animal to animal. The interindividual variation was not related to the level of the arterial pressure or to rectal temperature. Individual values for the PO 2 in 569 locations in the 11 cats ranged from 0 to 90 mm Hg with a mean of 25. There was a significant downward trend in PO 2 from the surface layers inward. When the electrode was left in one location, the PO 2 usually fluctuated, though not often rhythmically as seen in skeletal muscle. Breathing pure O 2 (N=41) or 95% O 2 -5% CO 2 (N = 33) caused an equal (50%) increase in PO 2 . The intravenous injection of epinephrine or norepinephrine caused a primary rise in PO 2 usually with a secondary decrease. Acetylcholine caused a primary decrease and usually a secondary increase.

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“…It is now well recognized that the cyclic nature of breathing generates oscillations of arterial blood composition about a mean level (Nims & Marshall, 1938;Honda & Veda, 1961;Purves, 1966;Band, Cameron & Semple, 1969). The question which remains unanswered is whether or not these oscillations can, in turn, affect breathing.…”

Section: Introductionmentioning

confidence: 99%

Dependence of phrenic motoneurone output on the oscillatory component of arterial blood gas composition.

Cross¹,

Grant²,

Guz³

et al. 1979

The Journal of Physiology

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SUMMARY1. The hypothesis that respiratory oscillations of arterial blood gas composition influence ventilation has been examined.2. Phrenic motoneurone output recorded in the C5 root of the left phrenic nerve and the respiratory oscillations of arterial pH in the right common carotid artery were measured in vagotomized anaesthetized dogs which had been paralysed and artificially ventilated.3. The effect of a change in tidal volume for one or two breaths on phrenic motoneurone output was measured with the inspiratory pump set at a constant frequency similar to, and in phase with, the animal's own respiratory frequency. A reduction of tidal volume to zero or an increase by 30 % led to a corresponding change of mean carotid artery pH level. The changes of carotid artery pH resulted in a change of phrenic motoneurone output, predominantly of expiratory time (Te) but to a lesser extent of inspiratory time (TI) and also peak amplitude of 'integrated' phrenic motoneurone output (Phr). Denervation of the carotid bifurcation blocked this response.4. The onset of movement of the inspiratory pump was triggered by the onset of phrenic motoneurone output. When a time delay was interposed between them, the phase relationship between respiratory oscillations of arterial pH and phrenic motoneurone output altered. The dominant effect was to alter Te; smaller and less consistent changes of Phr and Ti were observed.5. When the inspiratory pump was maintained at a constant frequency but independent of and slightly different from the animal's own respiratory frequency (as judged by phrenic motoneurone output), the phase relationship between phrenic motoneurone output and the respiratory oscillations of pH changed breath by breath over a sequence of 100-200 breaths, without change of the mean level of arterial blood gas composition. Te varied by up to 30 % about its mean value depending on the phase relationship. Ti and Phr were also dependent on the phase relationship but varied to a lesser extent. The changes were comparable to the results obtained in paragraph 4.6. It was concluded that phrenic motoneurone output is dependent in part on its relationship to the respiratory oscillations of arterial blood gas composition.

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Fluctuations of arterial oxygen tension which have the same period as respiration

Cited by 85 publications

References 20 publications

Evaluation of Response Time of a Transcutaneous Oxygen Tension Electrode

Evaluation of Response Time of a Transcutaneous Oxygen Tension Electrode

Effects of Breathing O ₂ or O ₂ + CO ₂ and of the Injection of Neurohumors on the PO ₂ of Cat Cerebral Cortex

Dependence of phrenic motoneurone output on the oscillatory component of arterial blood gas composition.

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Fluctuations of arterial oxygen tension which have the same period as respiration

Cited by 85 publications

References 20 publications

Evaluation of Response Time of a Transcutaneous Oxygen Tension Electrode

Evaluation of Response Time of a Transcutaneous Oxygen Tension Electrode

Effects of Breathing O 2 or O 2 + CO 2 and of the Injection of Neurohumors on the PO 2 of Cat Cerebral Cortex

Dependence of phrenic motoneurone output on the oscillatory component of arterial blood gas composition.

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Effects of Breathing O ₂ or O ₂ + CO ₂ and of the Injection of Neurohumors on the PO ₂ of Cat Cerebral Cortex