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Titolo:
Critical closing pressure explains cerebral hemodynamics during the Valsalva maneuver
Autore:
Dawson, SL; Panerai, RB; Potter, JF;
Indirizzi:
Univics,cester, Glenfield Gen Hosp, Dept Med Elderly, Leicester LE3 9QP, Le Univ Leicester Leicester Leics England LE3 9QP rly, Leicester LE3 9QP, Le Leicester Royal Infirm, Dept Phys Med, Leicester LE1 5WW, Leics, England Leicester Royal Infirm Leicester Leics England LE1 5WW WW, Leics, England
Titolo Testata:
JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 2, volume: 86, anno: 1999,
pagine: 675 - 680
SICI:
8750-7587(199902)86:2<675:CCPECH>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
BLOOD-FLOW VELOCITY; TRANSCRANIAL DOPPLER; REFLEX SENSITIVITY; PHASE-IV; CIRCULATION; ARTERIES; INDEX; RESISTANCE;
Keywords:
cerebral blood flow; cerebral autoregulation; cerebrovascular resistance;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
23
Recensione:
Indirizzi per estratti:
Indirizzo: Dawson, SL Leicesters,en Hosp, Dept Med Elderly, Gwendolen Rd, Leicester LE5 4PW, Leic Leicester Gen Hosp Gwendolen Rd Leicester Leics England LE5 4PW
Citazione:
S.L. Dawson et al., "Critical closing pressure explains cerebral hemodynamics during the Valsalva maneuver", J APP PHYSL, 86(2), 1999, pp. 675-680

Abstract

The Valsalva maneuver (VM), a voluntary increase in intrathoracic pressureof similar to 40 mmHg, has been used to examine cerebral autoregulation (CA). During phase IV of the VM there are pronounced changes in mean arterialblood pressure (MABP), pulse interval, and cerebral blood flow (CBF), but the changes in CBF are of a much greater magnitude than those seen in MABP,a finding to date attributed to either a delay in activation of the CA mechanism or the inability of this mechanism to cope with the size and speed of the blood pressure changes involved. These changes in CBF also precede those in MABP, a pattern of events not explained by the physiological processof CA. Measurements of CBF velocity (transcranial Doppler) and MABP (Finapres) were performed in 53 healthy volunteers (aged 31-80 yr). By calculating beat-to-beat values of critical closing pressure (CCP) during the VM, we have found that this parameter suddenly drops at the start of phase TV, providing a coherent explanation for the large increase in CBF. If CCP is included in the estimation of cerebrovascular resistance, a temporal pattern more consistent with an autoregulatory response to the MABP overshoot is alsofound. CCP is intricately involved in the control of CBF during the VM andshould be considered in the assessment of CA.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/11/20 alle ore 03:02:40