As it arrives at the wound surface, this fluid may be contaminated with tissue debris and micro-organisms . London: Quay Books, 2004 .] In chronic wounds the inflammatory response is altered owing to an uncontrolled expression of inflammatory mediators with a concurrent increase in vascular permeability and the amount of extravascular fluid.
Healing acute wounds produce exudate containing active growth factors. Modest amounts of thin, pale yellow or straw-coloured exudate in an acute healing wound is considered normal. Some bacteria produce fibrinolysins, which degrade fibrin clots or coagulated plasma. If the wound becomes infected, an abrupt increase in exudate volume may be seen initially, followed by further quantitative and qualitative changes.
Certain bacteria such as Pseudomonas aeruginosa stimulate the release of HBP from neutrophils, thus aggravating chronic inflammation by augmenting endothelial hyper-permeability .
It has a high protein content (although lower than that found in serum), with a specific gravity greater than 1.020.
Inspection of a dressing on removal may yield valuable information on the level of exudate produced during dressing wear time.
To assess the exudate volume the healthcare practitioner should count the number of dressings used over a time period, note the wear time for individual dressings, examine the dressing for the presence of strikethrough (wet or dry), examine the peri-wound skin condition and note any leakage .
It has also been shown that chronic leg ulcer exudate contains increased levels of HBP when compared to acute wound fluid .
It is likely that HBPs are implicated in the production of increased exudate.