Table 5 Summary of the effect of in-flight venous interventions.

LBNP

Application of LBNP (−25 mmHg and −45 mmHg of 10 min with a transition step of −35 mmHg): The calf volume increased as the pressure decreased (Arbeille et al.)²⁸.

Application of LBNP −25 mmHg restored variables at least back to pre-flight supine levels. From reported figure: IJV volume returns to pre-flight supine level in 10/12 astronauts (Arbeille et al.)¹⁶.

LBNP −25 mmHg reduced IJV area and improved blood flow (Marshall-Goebel et al.)².

LBNP −45 mmHg: Less increase of calf circumference, femoral resistance, and cerebral/femoral blood flow ratio inflight/postflight than pre-flight (Herault et al.)²¹.

Cuffs (Bracelets)

With versus without cuffs: decreased jugular area, increased femoral area (Herault et al.)²¹.

Reduction of cephalic congestion and jugular vein area, no noticeable effect on cerebral blood flow, femoral vein area higher (Fomina et al.)¹⁹.

Increased femoral vein area, decreased IJV area (Hamilton et al.)²⁰.

Respiratory manoeuvres

Increased femoral vein area with bracelets, little additional increase with bracelets + Valsalva (Hamilton et al.)²⁰.

Increased femoral vein with Valsalva (Hamilton et al.)²⁰.

IJV pressure appears to increase as the level of gravity decreases (Martin et al.)²⁴.

Decreased IJV area with bracelets, Mueller and both bracelets + Mueller (Hamilton et al.)²⁰.

Flow induced by Mueller manoeuvre (Auñón-Chancellor et al.)¹.

Modified Mueller increased peak velocity and reduced echogencity (Pavela et al.)²⁵.

Modified Mueller and contralateral compression reversed the flow direction to antegrade (Pavela et al.)²⁵.