Lower body negative pressure protects brain perfusion in aviation gravitational stress induced by push–pull manoeuvre

Abstract

Rapid alterations of gravitational stress during high-performance aircraft push-pull manoeuvres induce dramatic shifts in volume and pressure within the circulation system, which may result in loss of consciousness due to the rapid and significant reduction in cerebral perfusion. There are still no specific and effective countermeasures so far. r We found that lower body negative pressure (LBNP), applied prior to and during −Gz and released at the subsequent transition to +Gz, could effectively counteract gravitational haemodynamic stress induced by a simulated push-pull manoeuvre and improve cerebral diastolic perfusion in human subjects. r We developed a LBNP strategy that effectively protects cerebral perfusion at rapid −Gz to +Gz transitions via improving cerebral blood flow and blood pressure during push-pull manoeuvres and highlight the importance of the timing of the intervention. r Our findings provide a systemic link of integrated responses between the peripheral and cerebral haemodynamic changes during push-pull manoeuvres.

Pulling back on the push–pull effect: use of lower body negative pressure to protect against drops in cerebral perfusion during airflight manoeuvres

“…In this issue of The Journal of Physiology , Xing et al . (2020) implemented an elegant and straightforward strategy for preserving cerebral perfusion during the push–pull manoeuvre. As moderate levels of lower body negative pressure (LBNP) redistributes blood volume without affecting arterial pressure, Xing et al .…”

“…As moderate levels of lower body negative pressure (LBNP) redistributes blood volume without affecting arterial pressure, Xing et al . (2020) measured systemic and cerebral haemodynamics during a simulated push–pull manoeuvre at two levels of hypogravity (−0.50 G and −0.87 G), with and without (control) application of LBNP at −40 mmHg. Two variations of the push phase consisted of a head down tilt (HDT) at −30° or −60° corresponding to −0.50 G or −0.87 G, respectively.…”

“…Xing et al . (2020) found that application of LBNP prior to and during transition from HDT to HUT could serve as a means to preserve cerebral perfusion during a simulated push–pull manoeuvre. Such findings provide novel and necessary information when considering future strategies for preserving cerebral perfusion during airflight manoeuvres.…”

Lower body negative pressure: a novel remedy for preserving the cerebrovasculature from gravitational stress

“…Interestingly, Xing and colleagues found that pulsatility index (PI) was lower in LBNP bouts during the HDT–HUT transition period (Xing et al . 2020). Increases in PI during HDT indicates vasoconstriction of cerebral resistance vessels, which occurs as a result of the hydrostatic pressure gradient mentioned above.…”

“…A recent publication by Xing et al . (2020) in The Journal of Physiology examines an alternative strategy to counteract the negative haemodynamic effects of PPM by incorporating lower body negative pressures (LBNP) in a simulated PPM environment.…”