The water vapour transmission rate (WVTR) of 14 commercially available
synthetic wound dressings (11 hydrocolloids, 2 hydrogels and 1 polyur
ethane film) was evaluated over 24 and 48 h periods using a modified A
STM standard method (ASTM E96-90). For the 48 h studies a novel microc
omputer-controlled apparatus was employed. The dressings exhibited a w
ide range of WVTRs (76-9360 g m(-2) d(-1) at 24 h under forced air con
vection of 0.4 m s(-1)). The influence of air velocity of 0.4 m s(-1)
was not significant if the WVTR of the dressing was less than 880 g m(
-2) d(-1) when measured under static air conditions. The influence of
outer barrier layers and additional bandages on WVTR was also examined
.