Effect of Pa _{CO CO2} on Blood Flow and Microvasculature of Ischemic and Nonischemic Cerebral Cortex

Abstract

Effect of Paco,, on Blood Flow and Microvasculature of Ischemic and Nonischemic Cerebral Cortex

Cerebral Ischemia and Reactive Hyperemia

“…85 Kr dissolved in physiologic saline to which was added a small amount of heparin was injected with an automatic injector in volumes of approximately 0.3 ml during 3 seconds into the catheter in the stump of the external carotid artery, delivering the entire bolus to the internal carotid circulation. The appearance and clearance of the beta activity of the diffusible radioactive indicator from the brain were recorded on magnetic tape and by rate meters and strip recorders (6,9). Pulses were counted from the magnetic tape with a two-channel digital rate meter.…”

“…Special attention was paid to the development or absence of cerebral edema and to the color of venous blood. In one animal these alterations were photographed by a technique previously described (2, 9). During and after occlusion, values of importance were recorded, including the mean arterial blood pressure, arterial Pco 2 , arterial pH, arterial Po 2 , and hematocrit.…”

“…• The concept of hyperemia or "luxury perfusion" (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) in relation to cerebral ischemia is generally accepted, but as yet there has been no documentation of the degree or extent of such a phenomenon after restoration of blood flow to an area of brain subjected to a known degree and period of ischemia. We chose the squirrel monkey for a study of such flow changes because of our extensive experience (180 animals) with a laboratory model of cerebral infarction in this species.…”

Chapter 14 Cerebral vascular dysregulation in the ischemic brain

“…Such reversal of hypercapnic vasodilation to vasoconstriction has been attributed to a ‘steal’ of blood flow into neighboring areas where CO 2 reactivity is retained (Symon et al, 1974). Although this phenomenon has been confirmed in some animal studies (Waltz, 1970; Paulson, 1971; Symon et al, 1971; Ott et al, 1975; Olah et al, 2000), other studies could not find evidence for an intracerebral steal in hypercapnia (Olsen et al, 1983; Jones et al, 1989) or during administration of cerebrovasodilators (Date and Hossmann, 1984; Gogolak et al, 1985). Therefore, the existence of an intracerebral steal phenomenon during hypercapnia or vasodilator administration remains controversial.…”

Arterial carbon dioxide tension after cardiac arrest: Too little, too much, or just right?

“…16–19 Reactivity of the arterioles in the cortical microvasculature was variable after focal ischemia and this was postulated to be secondary to ischemic damage to the vessel wall. 20 It is reasonable to hypothesize that there is regional variability and insult-duration variability to carbon dioxide in patients post-arrest.…”