Is the ICP pulse waveform P2/P1 ratio during -6° head-down tilt associated with relative VO2 peak? A non-invasive intracranial compliance monitoring approach

• Published in: Brain & spine Vol. 4; p. 103327
• Main Authors: Mendes Zambetta, Rafaella, Signini, Étore De Favari, Catai, Aparecida Maria, Santos, Thainá Cristina Ramos dos, Michaliski, Eloisa Soares, Nazario, Ana Karoline, Ocamoto, Gabriela Nagai, Frigieri, Gustavo, Russo, Thiago Luiz
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2024; Elsevier
• Subjects: Intracranial compliance; Intracranial pressure; Physical fitness; Special Issue Section: ICP 2022; Weightlessness simulations; Intracranial compliance; Physical fitness; Intracranial pressure; Weightlessness simulations
• ISSN: 2772-5294; 2772-5294
• DOI: 10.1016/j.bas.2024.103327

Spaceflights influence intracranial compliance (ICC). P2/P1 ratio, from the intracranial pressure (ICP) waveform, provides information about ICC. Additionally, non-invasive methods for ICC monitoring are needed for spaceflights. Furthermore, astronauts try to maintain good levels of cardiorespiratory fitness before and during spaceflights, not only to sustain exploratory missions, but also to prevent diseases in extreme environments. to correlate cardiorespiratory fitness levels with the P2/P1 ratio during a microgravity analog [-6° head-down tilt (HDT)]. 34 individuals (11 women), mean age of 31.7 (±6.3) years and BMI 24.2 (±3.2) performed a cardiopulmonary exercise testing (CPET) with an incremental protocol on a cycle ergometer to determine the cardiopulmonary fitness through peak relative oxygen uptake (VO2 peak) of each individual. On the second test, which was conducted in an interval of 15 days of the CPET, participants remained for 30 min at HDT with P2/P1 ratio acquired using a non-invasive strain gauge sensor. The average of the last 5 min was used for analysis. The mean P2/P1 ratio and relative VO2 peak were correlated using the Spearman test. Volunteers presented 1.05 ± 0.2 of P2/P1 ratio and VO2 peak of 47.5 ± 7.6 mL/kg/min. The Spearman test indicated a negative and low correlation between the P2/P1 ratio and VO2 peak (ρ = -0.388; p = 0.023). The study suggests that the better the cardiorespiratory fitness, the better ICC in a weightlessness simulation. •Cardiorespiratory fitness possibly influences intracranial compliance.•Sex should be considered for intracranial compliance associated with physical fitness.•Non-invasive ICP monitoring is an option to assess and relate physical fitness to ICP.•Fitness levels should be a factor to consider in ICP adjustments to weightlessness.