Dissociation between Cerebral Autoregulation and Carbon Dioxide Reactivity during Nonpulsatile Cardiopulmonary Bypass

Lundar, Tryggve; Lindegaard, Karl-Fredrik; Frøysaker, Tor; Aaslid, Rune; Grip, Arne; Nornes, Helge

doi:10.1016/s0003-4975(10)60353-0

Cited by 72 publications

(27 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Several studies have shown that in certain conditions, pressure autoregulation can be impaired despite normal values of CO 2 reactivity [2, 3]. Thus, there is an increasing number of studies in which both aspects of CBF regulation are independently investigated [4].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 1999

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%

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

et al. 1999

View full text Add to dashboard Cite

show abstract

“…Indeed, these 2 cerebral vasodilations may imply different mechanisms. 7 However, this question is still a matter of debate, and a recent report supports the use of the ACZ test to measure the cerebral autoregulatory capacity. 8 Nevertheless, it is not certain that the results of an ACZ test provide See Editorial Comment, page 514 valuable information on the brain's capacity to adapt to hypotension or hypoperfusion.…”

mentioning

confidence: 99%

Is the Acetazolamide Test Valid for Quantitative Assessment of Maximal Cerebral Autoregulatory Vasodilation?

Démolis

Florence²,

Thomas³

et al. 2000

Stroke

View full text Add to dashboard Cite

Background and Purpose-The cerebral vasodilating effect of acetazolamide (ACZ) injection has been used as an index of the autoregulatory vasodilation (or cerebral perfusion reserve). The question of whether the ACZ test assesses the maximal autoregulatory vasodilating capacity is not definitely resolved. The effects of ACZ injection on this reserve at a dose producing maximal vasodilation have never been evaluated and may help to resolve this problem. Methods-The effect of ACZ injection on cerebral blood flow (CBF) autoregulation was tested in anesthetized rats. A pilot experiment evaluated the dose-effect relationship of injected ACZ, cumulative doses (nϭ4, group 1), and independent bolus doses (nϭ6, group 2). CBF was estimated by laser-Doppler flowmetry, and cerebrovascular resistance (CVR) was calculated from mean arterial blood pressure (MABP) and from CBF (expressed as a percentage of baseline CBF). A bolus of ACZ of 21 mg/kg produced the maximal cerebral vasodilation that could be obtained by ACZ administration. In the main experiment, MABP was lowered from 110 to 20 mm Hg by stepwise bleeding in 3 groups of 6 animals treated 10 minutes before bleeding by injection of saline (group 3), 7 mg/kg ACZ (group 4), or 21 mg/kg ACZ (group 5). Results-The CVR-MABP relationship was linear in all groups, indicating that CBF autoregulation was still effective after ACZ administration. Conclusions-These results indicate that maximal ACZ-induced cerebral vasodilation is not quantitatively equivalent to maximal autoregulatory vasodilating capacity in anesthetized rats. (Stroke. 2000;31:508-515.)

show abstract

“…), the so-called 'dissociated vasoparalysis' [34,55,56,65]. In addition, it has been suggested that occasionally, partial or complete restoration of normal autoregulation can be brought about by moderate hypocapnia [55].…”

Section: Introductionmentioning

confidence: 99%

“…Harper, among others, has shown in animal experiments that hypercapnia can induce a righthand shift of the autoregulatory curve [28,55]. Although less studied in head injury, this dissociated paralysis has been observed in other clinical situations in which the brain is threatened such as in nonpulsatile cardiopulmonary bypass [34]. The theoretical combination of preserved CO2-reactivity and impaired or abolished autoregulation can have many clinical implications in the daily management of brain injured patients.…”

Section: Introductionmentioning

confidence: 99%

Arterio-jugular differences of oxygen (AVDO2) for bedside assessment of CO2-reactivity and autoregulation in the acute phase of severe head injury

et al. 1996

View full text Add to dashboard Cite

Autoregulation and CO2-reactivity can be impaired independently of each other in many brain insults, the so-called 'dissociated vasoparalysis'. The theoretical combination of preserved CO2-reactivity and impaired or abolished autoregulation can have many clinical implications in the daily management of brain injured patients. To optimize their treatment, a bedside assessment of autoregulation and CO2-reactivity is desirable. When cerebral metabolic rate of oxygen is constant, changes in arterio-jugular differences of oxygen (AVDO2) reflect changes in CBF. In these situations relative changes in AVDO2 can be viewed as inverse changes in CBF and used as an evaluation method of CO2-reactivity and autoregulation. In 39 consecutive severe head injury patients with a mean age of 28 +/- 17 years and a diffuse brain injury, cerebrovascular response to changes in pCO2 was tested in the acute phase after injury (18 +/- 8 hours). In 28 of those cases autoregulation was also assessed. A relative CBF value (1/AVDO2) was calculated from baseline AVDO2 and was expressed as 100%. Changes in 1/AVDO2 after inducing pCO2 changes give a good estimate of changes in global CBF. Two different indexes were calculated for CO2-reactivity: 1) absolute CO2-reactivity (CO2RABS) and 2) percentage reactivity (CO2R%). CO2R% was used to separate patients with impaired/abolished CO2-reactivity from those with preserved CO2-reactivity. Patients with CO2R% above 1% were considered in the intact CO2-reactivity group and patients in whom CO2R% was below or equal to 1% were included in the impaired/abolished CO2-reactivity group. Only five cases (12.8%) presented an impaired/abolished CO2-reactivity. AVDO2 response to induced hypertension was studied in a subset of 28 patients. Phenylephrine was used to increase MABP about 25%. All AVDO2 values were corrected for changes in pCO2. Patients with changes in 1/AVDO2 less than or equal to 20% were included in the intact autoregulation group. Patients with estimated CBF changes above 20% were classified as having an impaired autoregulation (impaired/abolished). In 12 patients (43%) autoregulation was intact. In the remaining 16 patients (57%) autoregulation was imparied. Of the 28 cases, CO2-reactivity was impaired in only five cases. All patients with an impaired CO2-reactivity also had an impaired autoregulation. Monitoring relative changes in AVDO2 permits a reliable study of CO2-reactivity and autoregulation at the bedside. Introducing these variables into the day-to-day management should be considered in treatment protocols.

show abstract

Dissociation between Cerebral Autoregulation and Carbon Dioxide Reactivity during Nonpulsatile Cardiopulmonary Bypass

Cited by 72 publications

References 19 publications

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

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

Is the Acetazolamide Test Valid for Quantitative Assessment of Maximal Cerebral Autoregulatory Vasodilation?

Arterio-jugular differences of oxygen (AVDO2) for bedside assessment of CO2-reactivity and autoregulation in the acute phase of severe head injury

Contact Info

Product

Resources

About