Cerebral autoregulation and ageing

Yam, Alan; Lang, E; Lagopoulos, Jim; Yip, Kwok; Griffith, Jane; Mudaliar, Yugan; Dorsch, Nicholas W.C.

doi:10.1016/j.jocn.2004.08.017

Cited by 56 publications

(47 citation statements)

References 21 publications

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“…CBF during mild-to-moderate intensity exercise: influence of age Despite no disturbances to total cerebral oxygen consumption with healthy aging, there is a progressive decline in CBF (approximately 28-50%) from 30 to 70 years of age (Yam et al 2005;Ainslie et al 2008;Fisher et al 2008;Ogoh and Ainslie 2009) that is associated with global cerebral atrophy Buijs et al 1998). In contrast to healthy YA, as mentioned, only two studies (Fisher et al 2008;Heckmann et al 2003) have examined CBF in middle-aged OA during mild-to-moderate exercise.…”

Section: Discussionmentioning

confidence: 99%

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Aging blunts hyperventilation-induced hypocapnia and reduction in cerebral blood flow velocity during maximal exercise

Marsden

Haykowsky

Smirl

et al. 2011

AGE

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Cerebral blood flow (CBF) increases from rest to ∼60% of peak oxygen uptake (VO 2peak ) and thereafter decreases towards baseline due to hyperventilation-induced hypocapnia and subsequent cerebral vasoconstriction. It is unknown what happens to CBF in older adults (OA), who experience a decline in CBF at rest coupled with a blunted ventilatory response during VO 2peak . In 14 OA (71±10 year) and 21 young controls (YA; 23±4 years), we hypothesized that OA would experience less hyperventilationinduced cerebral vasoconstriction and therefore an attenuated reduction in CBF at VO 2peak . Incremental exercise was performed on a cycle ergometer, whilst bilateral middle cerebral artery blood flow velocity (MCA V mean ; transcranial Doppler ultrasound), heart rate (HR; ECG) and end-tidal PCO 2 (P ET CO 2 ) were monitored continuously. Blood pressure (BP) was monitored intermittently. From rest to 50% of VO 2peak , despite greater elevations in BP in OA, the change in MCA V mean was greater in YA compared to OA (28% vs. 15%, respectively; P<0.0005). In the YA, at intensities >70% of VO 2peak , the hyperventilationinduced declines in both P ET CO 2 (14 mmHg (YA) vs. 4 mmHg (OA); P<0.05) and MCA V mean (−21% (YA) vs. −7% (OA); P<0.0005) were greater in YA compared to OA. Our findings show (1), from rest-tomild intensity exercise (50% VO 2peak ), elevations in CBF are reduced in OA and (2) age-related declines in hyperventilation during maximal exercise result in less hypocapnic-induced cerebral vasoconstriction.

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Section: Discussionmentioning

confidence: 99%

“…With healthy aging, there is a progressive decline in CBF (approx: 28-50%) from 30 to 70 years of age (Yam et al 2005;Ainslie et al 2008;Fisher et al 2008;Ogoh and Ainslie 2009). Such declines are caused by global cerebral atrophy without any disturbance in cerebral oxygen consumption Buijs et al 1998).…”

mentioning

confidence: 99%

Aging blunts hyperventilation-induced hypocapnia and reduction in cerebral blood flow velocity during maximal exercise

Marsden

Haykowsky

Smirl

et al. 2011

AGE

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“…A difference in the Mx of [ 0.3 in patients with head injury showed clinical relevance, 9 while in another study comparing young vs old patients, a difference in the Mx of 0.1 was assumed to be clinically irrelevant. 10 Furthermore, the standard deviation in previously reported studies was about 0.2. 10,11 Consequently, in the present study, a change in Mx of C 0.2 between baseline and CVVHD measurement was defined as clinically relevant.…”

Section: Cvvhdmentioning

confidence: 86%

“…10 Furthermore, the standard deviation in previously reported studies was about 0.2. 10,11 Consequently, in the present study, a change in Mx of C 0.2 between baseline and CVVHD measurement was defined as clinically relevant. The null hypothesis of the equivalence test states that the Mx changes by [ 0.2; the alternative hypothesis maintains that this change is \ 0.2.…”

Section: Cvvhdmentioning

confidence: 86%

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Cerebrovascular autoregulation in critically ill patients during continuous hemodialysis

Schramm¹,

Closhen²,

Wojciechowski³

et al. 2013

Can J Anesth/J Can Anesth

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Purpose In chronic renal failure, intermittent hemodialysis decreases cerebral blood flow velocity (CBFV); however, in critically ill patients with acute renal failure, the effect of continuous venovenous hemodialysis (CVVHD) on CBFV and cerebrovascular autoregulation (AR) is unknown. Therefore, a study was undertaken to investigate the potential effect of CVVHD on CBFV and AR in patients with acute renal failure. Methods This cohort study investigated 20 patients with acute renal failure who required CVVHD. In these patients, the CBFV and index of AR (Mx) were measured using transcranial Doppler before and during CVVHD. Conclusion Compared with patients with intermittent hemodialysis, CVVHD did not influence CBFV and AR in critically ill patients with acute renal failure, possibly due to lower extracorporeal blood flow, slower change of plasma osmolarity, and a lower fluid extraction rate. In a subgroup of patients with sepsis, the AR was impaired at baseline in more than half of the patients, and this was reversed during CVVHD. The trial was registered at ClinicalTrials.gov ID: NCT01376531.Author contributions Patrick Schramm, Christian Werner, and Kristin Engelhard contributed to the conception and design of the study. Patrick Schramm, Dorothea Closhen, Janosch Wojciechowski, Klaus Ulrich Klein, Marc Bodenstein, Christian Werner, and Kristin Engelhard contributed to the acquisition of data. Patrick Schramm, Manfred Berres, Christian Werner, and Kristin Engelhard contributed to the analysis of the data. Patrick Schramm, Christian Werner, and Kristin Engelhard contributed to the interpretation of the data. Patrick Schramm drafted the article. Dorothea Closhen, Janosch Wojciechowski, Klaus Ulrich Klein, Marc Bodenstein, Manfred Berres, Christian Werner, and Kristin Engelhard contributed to revising the article for important intellectual content. Manfred Berres contributed to statistical planning. To avoid adverse effects of cerebral hypo-and hyperperfusion, cerebral blood flow is autoregulated within a wide range of arterial blood pressure changes. This so-called cerebrovascular autoregulation (AR) is impaired in patients with intracranial pathology 1,2 and, likewise, in critically ill septic patients without cerebral pathologies.3 These patients often develop further organ dysfunction, such as acute renal failure with the consequent need for renal replacement therapy. Extracorporeal continuous venovenous hemodialysis (CVVHD) is one kind of renal replacement therapy used in the intensive care unit (ICU) in critically ill patients.

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