Sex differences in cerebral haemodynamics across the physiological range of PaCO2.
Authors of this article are:
Minhas JS Panerai RB Robinson TG.
A summary of the article is shown below:
Objective Cerebral blood flow (CBF) is influenced by changes in arterial CO<sub>2</sub> (PaCO<sub>2</sub>). Recently, cerebral hemodynamic parameters were demonstrated to follow a four parameter logistic curve offering simultaneous assessment of dCA and CO<sub>2</sub> vasoreactivity. However, the effects of sex on cerebral haemodynamics have yet to be described over a wide range of PaCO<sub>2</sub>. Approach CBF velocity (CBFV, transcranial Doppler), blood pressure (BP, Finometer) and end-tidal CO<sub>2</sub> (EtCO<sub>2</sub>, capnography) were measured in healthy volunteers at baseline, and in response to hypo- (-5 mmHg and -10 mmHg below baseline) and hypercapnia (5% and 8% CO<sub>2</sub>), applied in random order. Main Results Forty-five subjects (19 male, 26 female, mean age 37.5 years) showed significant differences between males and females in CBFV (50.9±10.4 vs. 61.5±12.3 cm.s-1, p=0.004), EtCO<sub>2</sub> (39.2±2.8 vs. 36.9±3.0 mmHg, p=0.005), RAP (1.16±0.23 vs. 0.94±0.40 mmHg cm.s-1, p=0.005) and systolic BP (125.2±8.0 vs. 114.6±12.4 mmHg, p=0.0372), respectively. Significant differences between sexes were observed in the four logistic parameters: y<sub>min</sub>, y<sub>max</sub>, k (exponential coefficient) and x (EtCO<sub>2</sub> level) across the haemodynamic variables. Significant differences included the CBFV-EtCO<sub>2</sub> and ARI-EtCO<sub>2</sub> relationship; ARI<sub>min</sub> (p=0.036) and CBFV<sub>max</sub> (p=0.001), respectively. Furthermore, significant differences were observed for both CrCP<sub>min</sub> (p=0.045) and CrCP<sub>max</sub> (p=0.005) and RAP<sub>min</sub> (p<0.001) and RAP<sub>max</sub> (p<0.001). Significance This is the first study to examine sex individually within the context of a multi-level CO<sub>2</sub> protocol. The demonstration that the logistic curve parameters are influenced by sex, highlights the need to take into account sex differences between participants in both physiological and clinical studies.
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This article is a good source of information and a good way to become familiar with topics such as: Blood Pressure;Carbon Dioxide;Cerebral Circulation;Haemodynamics;Sex.
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