In our last blog, we discussed how and why chronic wounds form. We took a deep dive into Redox Biology and detailed the lack of regulatory control of ROS or Reactive Oxygen Species leading to changes within the ECM or Extracellular Matrix and therefore the formation of Biofilm.
An interesting article I recently studied concluded that Biofilm is present in all Chronic Wounds. Other literature concerning Chronic Wounds indicate the presence in 90% and the presence of Biofilm in 9% of Acute Wounds. Either way, I would have to agree with the former based on the presence of a wound without improvement over time. Given the fact that bacteria is present everywhere leads me to also believe that it can become facultative given the right conditions as mentioned above and become a detriment in wound healing. For instance, when you look at struggling wounds, there are features that immediately catch my attention such as hyperpigmentation surrounding the wound indicating chronicity along with pale and fragile granulation tissue due to the lack of oxygen. Rolled skin edges are another feature that I notice more frequently in chronic wounds as well resulting in the lack of keratinocytes migrating across the surface and the list goes on. The bottom-line up front is Biofilm, and just because you may not have findings of an acute infection present, does not mean that Biofilm is absent. I recall a story of a new intern who began his first day of residency training in the wound clinic. His first presentation was of a new patient with a malleolar wound of which he did not want to debride because there was no purulence, no erythema, no malodor and thought by using antibiotic ointment and dressings, the wound would heal based on the presentation. What the intern failed to ascertain was that the wound had been present for two months at roughly the same size regardless of how normal it appeared.
Question: Did you ever notice the presentation of a chronic wound before and after sharp debridement? If so, what was the difference? For me, it is rather simple-a healthier wound bed appearance following sharp debridement and especially the color. After sharp debridement, the wound seems to come alive and the tissues become better permeated with oxygen revealing blood, but also a vibrancy to the granulation tissue in the wound. Of course, this is assuming that there is good functional vascular integrity and proper infection control. And when you peruse the literature and really begin to understand that the glycocalyx formed by the Biofilm not only repels internal and external antibiosis and chemotactic defenses, it also decreases the oxygen partial pressure within the wound (9). Biofilm consumes a large amount of oxygen. The oxygen concentration at the biofilm-neutrophil juncture is diminished to hypoxic levels thus reducing neutrophil killing abilities. And if you have normal oxygen tension at the surface of the wound, the Redox Cascade functions more appropriately in the regulation of the antioxidants previously discussed (H2O2, OH, etc). In essence, the Oxygen partial pressure levels or tension at the wound surface decrease to 5-20 mm Hg in chronic wounds. Normal pressures range from 30-40 mm Hg (consider normal Transcutaneous Oxygen or TCO2 Measurements in mapping out pre-amputation zones for success and better outcomes). Therefore, sharp debridement not only removes the mature surface Biofilm colonies, but also helps restore the normal Oxygen partial pressures by decreasing Biofilms. Overall, there is a lot more than just concentrating on bacteria and antibiotics when dealing with Biofilm: but also, how Oxygen tension is paramount to wound healing and how oxygen delivery systems can benefit with sharp debridement.
Sharp Debridement has been shown in the literature as a proven modality for expedited and efficient alleviation of Biofilm and is considered as a necessity in the fight against Biofilm and Chronic Wounds. It is easy to see how Biofilm is not just a simply a “sticky slime” that seems to get in the way in wound care: it is actually a force to be reckoned with. In my next installment of wound bed preparation and the fight against Biofilm, we will continue our discussion and look at literature-based evidence on sharp debridement as well as innovative methodology in creating better wound trajectories in the treatment of chronic wounds. Please check back often and until next time, fair winds and following sees.
Dr. F. Derk