Flap monitoring by transcutaneous PO2 and PCO2: importance of transcutaneous PCO2 in determining follow-up treatment for compromised free flaps.

The authors conducted a two-part study to determine whether transcutaneous oxygen pressure (TcPO (2)) and transcutaneous carbon dioxide pressure (TcPCO (2)) can be used to monitor flap viability after transplantation. The first part was an animal study in which TcPO (2) and TcPCO (2) were measured in 10 epigastric island flaps subjected to arterial or venous ischemia. The second part was a clinical study in which both were measured in 27 free skin flaps. In the experimental study, TcPO (2) decreased to nearly 0 mmHg after 10 minutes of arterial and venous ischemia. TcPCO (2) increased to 100 mmHg after 60 minutes of either type of ischemia. In the clinical study, congestion was suspected in six flaps on the basis of clinical signs alone. Three congested flaps with TcPCO (2) more than 90 mmHg were selected for intervention. The remaining three congested flaps, with TcPCO (2) 80 mmHg or less, survived completely without further treatment. The TcPO (2) of all treated flaps and of the six flaps not requiring further treatment was 0 mmHg. Results of experimental study indicate that TcPO (2) is more sensitive than TcPCO (2) to flap ischemia. However, results of clinical study suggest that it is very hard to distinguish congested flaps from healthy flaps by TcPO (2) alone. The authors believe that a congested flap with a TcPCO (2) more than 90 mmHg requires further treatment.

Sarpogrelate hydrochloride, an antagonist of 5-hydroxytryptamine receptor, improves skin flap survival and suppresses thrombus formation in injured microvessels of rabbits.

The authors carried out two studies to examine the effects of the 5-hydroxytryptamine receptor antagonist, sarpogrelate hydrochloride (SH), on flap necrosis. The first study measured survival rates and included histologic examination of random-pattern skin flaps in rabbits. The second study assessed the time to complete obstruction of blood flow with the artificial thrombus formation method, and the time for leukocytes to adhere to the endothelium of microvessels in a rabbit-ear chamber. The treatment groups were injected with SH. The survival rates of skin flaps in the SH-treated group were increased significantly. Histologic examination of vessels in the control group revealed that vessels in the deep dermis were obstructed completely by thrombi, whereas such vessels were not obstructed in the SH-treated group. Thrombus formation time and leukocyte adhesion time in the SH-treated group were prolonged and decreased, respectively. Thus, SH maintained flap circulation and promoted flap survival by preventing thrombus formation.