The dynamic effect of PetCO2 on vertebral bloodflow in cats

Vis, André N.; Folgering, H.T.M.

doi:10.1016/0034-5687(80)90110-3

Cited by 10 publications

(6 citation statements)

References 22 publications

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“…The resultant asymmetrical response of the blood flow velocity is attributed to the asymmetry of the wash in and out times of the CO 2 stimulus. This same effect was originally observed in anaesthetised cats [13]and later described by Poulin et al [14]for healthy volunteers.…”

Section: Discussionsupporting

confidence: 70%

Cerebrovascular Response to Dynamic Changes in pCO<sub>2</sub>

et al. 1999

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Fifty-six subjects with carotid artery disease were assessed by measuring the cerebral blood flow velocity (CBFV) change in response to inhalation of 5% CO₂ in air whilst continuously monitoring the blood pressure (BP). Coherent averaging of the data characterised differences in CBFV, BP, resistance area product and critical closing pressure during changes in end-tidal CO₂ (ETCO₂). The results primarily demonstrate that the augmentation of ETCO₂ increases the CBFV and BP, causing a pressure autoregulatory response, and allows the processes of pressure autoregulation and cerebral vascular reserve to be differentiated.

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Section: Discussionsupporting

confidence: 70%

Cerebrovascular Response to Dynamic Changes in pCO<sub>2</sub>

et al. 1999

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“…Our findings are consistent with those of Dahlgren, Ingvar & Siesjo (1981) and Kagstrom et al (1983) who also found a 3-fold increase of flow in various grey matter areas of the brain when Pa,co2 increased 35-40 torr. Vis & Folgering (1980) reported a 3-fold increase of vertebral flow when PET,C02 was increased 30 torr. Feustal et al (1984) found a smaller increase, 193-fold for an increase of Pa co2 of 12-6 torr, but this again may be low because barbiturate anaesthesia reduces the responsiveness of cerebral blood vessels to changes of CO2 (Edvinsson & McCulloch, 1981).…”

Section: Relation Between Phrenic Activity and Medullary Ecf [H+]mentioning

confidence: 97%

“…It can be seen that flow reaches a stable level by approximately a minute after the step change of PaXO2. The half-time of the change is approximately 13 s. A number of investigators have determined the response of cerebral blood flow to changes of Pa,co, in human beings, cats and dogs (Shapiro, Wasserman & Patterson, 1965Severinghaus & Lassen, 1967;Tuteur, Reveich, Goldberg, Cooper, West, McHenry & Cherniack, 1976;Vis & Folgering, 1980;Wilson, Trystman & Rapela, 1985). A problem with most of these studies is that the change of CO2 was made at the mouth during spontaneous breathing or during constant ventilation in paralysed animals.…”

Section: Relation Between Phrenic Activity and Medullary Ecf [H+]mentioning

confidence: 99%

Dynamics of medullary hydrogen ion and respiratory responses to square‐wave change of arterial carbon dioxide in cats.

Eldridge

Kiley

Paydarfar

1987

The Journal of Physiology

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1. The dynamics of changes of medullary extracellular fluid (ECF) hydrogen ion concentration ([H+]) and respiration, measured as integrated phrenic nerve activity, were determined in anaesthetized, paralysed, vagotomized and glomectomized cats. ECF [H+] was measured directly by means of a small (2 mm diameter) glass pH electrode placed on the ventral surface of the medulla. The variables were measured continuously after a step change of arterial PCO2 produced by abruptly starting or stopping an infusion of hypercapnic fluid into the aortic arch. 2. Alteration of pH in the descending thoracic aorta at the onset or offset of infusion was complete within 1.5 s after the change began, indicating that it was nearly square wave in form. 3. In sixteen experiments, ECF [H+] began to fall within 2 s of offset of infusion, reflecting aortic-medullary circulation time. Thereafter, ECF [H+] decreased to a stable level over the next 5 min; the curve describing the decrease consisted of two exponential functions, one with a time constant (tau) of 9.5 +/- 0.6 s and a second with a tau of 53 +/- 3 s. 4. We interpret the findings at the offset of CO2 infusion in terms of CO2 wash-out from the medullary ECF. The slow function is associated with wash-out during stable medullary blood flow that develops after 1 min. The early fast function is associated with the decreasing medullary blood flow that occurs during the first minute after change from arterial hypercapnia to normocapnia. 5. We have estimated medullary blood flow using a mathematical model incorporating the two functions. The values obtained are consistent with those in the literature where other methods have been used. Changes of blood flow following the step change of CO2 are fairly rapid, half of the response occurring in 13 s. 6. The change of respiratory activity lags the change of stimulus expressed by [H+], throughout the recovery period and respiration requires up to 8 min to reach a stable level. We attribute this slow response to slow central neural respiratory dynamics, the respiratory after-discharge.

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“…Our study does not allow us to quantify how changes of these variables would affect the slope of the Pco2-pH relationship. However, we have calculated the effects of a 3-fold increase of medullary 187 F. L. ELDRIDGE, J. P. KILEY AND D. E. MILLHORN blood flow (Vis & Folgering, 1980;Feustel, Stafford, Allen & Severinghaus, 1981) and the associated Haldane and non-linearity factors. We find that the change of the arterial to tissue PCO, difference would be smaller than 2 torr.…”

Section: Respiratory Effects Of Medullar Y Ph Changesmentioning

confidence: 99%

“…PCO2, which will be higher than arterial but less than venous Pco, and which has been shown in the cortex to be slightly higher than the arithmetic mean of the two (Ponten & Siesjo, 1966). The tissue to arterial Pco, difference in the medulla has been reported to be about 3-5 torr in the normoxic, normocapnic cat (Stafford, Feustel & Severinghaus, 1983 (Vis & Folgering, 1980;Feustel, Stafford, Allen & Severinghaus, 1981) and the associated Haldane and non-linearity factors. We find that the change of the arterial to tissue PCO, difference would be smaller than 2 torr.…”

Section: Respiratory Effects Of Medullar Y Ph Changesmentioning

confidence: 99%