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Titolo:
Heart rate and blood pressure responses to plus Gz following varied-duration -Gz
Autore:
Goodman, LS; Banks, RD; Grissett, JD; Saunders, PL;
Indirizzi:
Def & Civil Inst Environm Med, Aerosp Life Support Sect, Toronto, ON M3M 3B9, Canada Def & Civil Inst Environm Med Toronto ON Canada M3M 3B9 N M3M 3B9, Canada
Titolo Testata:
AVIATION SPACE AND ENVIRONMENTAL MEDICINE
fascicolo: 2, volume: 71, anno: 2000,
pagine: 137 - 141
SICI:
0095-6562(200002)71:2<137:HRABPR>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
PULL;
Keywords:
positive acceleration; negative acceleration; cardiovascular regulation; carotid-cardiac baroreflex; push-pull effect;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
22
Recensione:
Indirizzi per estratti:
Indirizzo: Goodman, LS Def & Civil Inst Environm Med, Aerosp Life Support Sect, 1133 Sheppard AveW, Toronto, ON M3M 3B9, Canada Def & Civil Inst Environm Med 1133 Sheppard Ave W Toronto ON Canada M3M 3B9
Citazione:
L.S. Goodman et al., "Heart rate and blood pressure responses to plus Gz following varied-duration -Gz", AVIAT SP EN, 71(2), 2000, pp. 137-141

Abstract

Background: The push-pull effect has been defined previously as decreased Gz tolerance caused by previous baseline zero or -Gz exposure. Earlier work indicates that the delay in BP (BP) recovery during + Gz is a function oftime at -Gz, and is due to the lengthened time-course of sympathetically mediated peripheral vasoconstriction. Hypothesis: The purpose of this study was to retrospectively determine whether heart rate (HR) varies with BP as duration at preceding -Gz increased. Methods: Continuous ECG R-R interval data from 15 s of +2.25Gz after preceding 2, 5, 10, or 15 s at -2Gz obtainedfrom previous experiments were analyzed and compared with the previously reported BP data. Repeated measures ANOVA and regression analyses were used to compare +2.25Gz HR responses after the four -Gz conditions and one control +2.25Gz condition. Results: An initial rapid rise in HR was observed forall conditions with a consistent steady-state plateau achieved after the first 7 s of +2.25Gz. However, there were significant differences in mean HRattained during the +2.25Gz plateau for preceding 15 s -2.0 Gz vs. the control,, 5, and 10s -Gz conditions (109 +/- 1.1 vs. 102 +/- 1.8, 100 +/- 2.0,97 +/- 1.1 and 101 +/- 1.1, bpm, respectively; p < 0.05). Conclusions: HR,unlike BP, increases briskly across all preceding -Gz time conditions, adapting within the initial baroreflex-compensatory time frame typically expected for +Gz exposures. These results suggest there may be a threshold effect for HR response. Consequently, vasoconstrictor response is a critical adaptive mechanism during + Gz when preceded by long (>10 s) -Gz exposures.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/12/20 alle ore 05:52:09