Duration after wounding (without antimicrobial treatment) Events Outcome Role of LAD
<6-8 hrs Environment microorganisms reach over the wound Wound contamination Barrier by polythene andaseptic LAD wash usingnegative pressurereduces chances ofcontamination
6-8 hrs Microorganisms starts growing over the wound Wound colonization, production harmful bacterial enzymes/toxins and formation of biofilm may start LAD wash andintermittent negativepressure every 4thhourly reduces chancesof colonization, removesharmful chemicals andbreaks biofilm barrier
After 6-8 hrs Microorganisms starts invading the viable tissue Wound invasion/wound sepsis (rapidity of invasion depends on quantitative bacterial count and virulence) Intermittent negativepressure every 4th hourly reducesĀ  chancesof invasion by reducing count and providingalternate strongernegative drainingchannel to lymphaticsand venules
Late events A. Proinflammatory cytokines produced in the wound is absorbed in systemic circulation
B. Microorganism gainsaccess to circulation
C. Bacteria startsproliferating in systemiccirculation
D. Hypotension Produced
E. Organ functionsderanged
Severe sepsis
Organ dysfunction/ Failure
Leech effect of LADreduces chances ofSIRS and organ failure(continuous suction may be done if required)(Bacteria may gainaccess to systemiccirculation through otherroute e.g. bacterial translocation, urinary tract, cheat infection)
Table 1: Role of intermittent (4th hourly) negative pressure of LAD in wound infection