A quantitative analysis of microcirculation during healing of split-thickness skin grafts in standardized full-thickness wounds.

BACKGROUND: Full-thickness skin defects often are managed with split-thickness skin grafting. The wound healing process, including formation of new vessels during the healing of skin grafts, is complex. OBJECTIVE: To evaluate the microcirculatory changes in the treated tissue after skin grafting to analyze perfusion dynamics during the wound healing process. MATERIALS AND METHODS: Fourteen full-thickness skin defects were created on the back of 14 adult male Lewis rats. All wounds were treated with autologous split-thickness skin grafts. The perfusion dynamics were assessed for 84 days with an O2C device that combines a laser light to determine blood flow and white light to determine postcapillary SO2 and the rHb. RESULTS: Blood flow increased for 50 days after grafting. SO2 decreased in superficial skin layers (depth of 2 mm) and increased in deep skin layers (depth of 8 mm) during the entire observation period. The rHb increased until day 10 in superficial layers and until day 20 in deep tissue layers. CONCLUSION: The microcirculatory changes reflect the different phases of wound healing. Long after the skin transplants were macroscopically healed, alterations in microcirculation were still detected. These alterations were caused by the long-lasting changes in tissue metabolism due to the formation, conversion, and degradation of the dermal matrix and vessels during wound healing and scar formation.

Severe Burn Injuries - The Day the Sodium Starts Rising.

BACKGROUND/AIM: The current study was designed to evaluate the etiologies of hypernatremic episodes in patients with severe burn injuries in comparison to critically ill non-burn patients. PATIENTS AND METHODS: The retrospective data acquisition was limited to the first 14 days and to patients with at least 20% total body surface area (TBSA) 2nd degree burn injuries or more than 10% TBSA when including areas of 3rd degree burn injuries. The results were compared to the results of a previously published study that analyzed the risk factors for hypernatremia in 390 non-burn intensive care unit patients. RESULTS: In total, 120 patients with a total of 50 hypernatremic episodes were included. Compared to non-burn injury patients, no significant differences were detectable except for a lower rate of hypokalemia and a higher rate of mechanical ventilation. The main trigger for hypernatremic episodes was the loss of free water, while 24% of the hypernatremic episodes seemed to be at least partly triggered by a surplus sodium influx. Patients with hypernatremic episodes had a significantly higher mortality rate. However, in none of the cases was hypernatremia the decisive cause of death. CONCLUSION: Besides the unique phenomenon of high volume internal and external volume shifts, the overall risk factors and etiologies of hypernatremia in patients with severe burn injury do not seem to significantly differ from other ICU patient collectives. Remarkably, a surplus of sodium influx and therefore a modifiable factor besides the specific burn injury volume resuscitation had an impact on the hypernatremic episodes in 24% of cases.

Mapping of Thoracodorsal Artery Perforators: Accuracy of Thermography and Handheld Doppler.

BACKGROUND: The versatile musculocutaneous latissimus dorsi flap and the thoracodorsal artery (TDA) perforator flap have developed into indispensable approaches in reconstructive surgery. While the anatomy of the TDA is consistent, the skin perforators vary in location and course. Dynamic infrared thermography (DIRT) recently gained popularity for perforator identification; however, its use and accuracy in thoracodorsal artery perforator (TDAP) mapping is yet to be determined. METHODS: TDAPs were visualized in 50 cases by DIRT. Based on the thermographic hotspots, the corresponding perforators were then identified by color duplex ultrasound (CDU) and handheld Doppler in a blinded fashion by two separate examiners. RESULTS: The midpoint of all perforator fascia passages was localized 99.7 mm caudal and 13.5 mm medial of the posterior axillary fold. The positive predictive value of perforator identification by dynamic infrared thermography was 86.5% and the correlating perforator fascia passage was 9.9 ± 5.8 mm from the hotspot midpoint, with a maximum of 29 mm. The positive predictive value of perforator identification by handheld Doppler was 95% and the signal was 7.2 ± 5.1 mm from the perforator fascia passage. CONCLUSION: DIRT precisely localizes TDAPs. The fusion with CDU combines both modalities' advantages. The combination with handheld Doppler is a fast way of perforator imaging, decreasing the handheld Dopplers' high false positive rate.