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Sex differences in cerebral haemodynamics across the physiological range of PaCO2.

A new interesting article has been published in Physiol Meas. 2018 Sep 26. doi: 10.1088/1361-6579/aae469. and titled:

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.

Check out the article’s website on Pubmed for more information:



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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