To compare measurements of skin perfusion pressure (SPP) and transcutaneous oxygen pressure (TcPO2) to predict postamputation wound healing according to amputation level. This study was conducted as a prospective two-centre, head-to-head study. Fifty-two patients had SPP, TcPO2 measured (below and above the knee), and toe and ankle blood pressure measurements taken before major amputation. Paired measurements of SPP and TcPO2 were used to compare the methods. We found overall poor agreement between SPP and TcPO2 measurements, with crude agreement below the knee in 32 of 45 limbs (71%) and above the knee in 17 of 23 limbs (74%), with κ values of 0.32 and 0.13, respectively. Among the 29 patients whose SPP measurements below the knee indicated healing potential, seven were amputated above the knee. Blood pressure measurements above the cut-off values (30 mmHg for the toe and 80 mmHg for the ankle, above 40 mmHg SPP and TcPO2 values), were seen as an indicator of high healing potential. We found poor (71%-74%) crude agreement between SPP and TcPO2, concerning measurements above and below the knee, using the established diagnostic cut-offs for predicting a high probability of postamputation wound healing. We determined that SPP and TcPO2 evaluate different physiological properties of the microcirculation and cannot be interchanged. Additionally, we found that the actual amputation level is often chosen at another level than that suggested by SPP and TcPO2, indicating that the choice is based on a multitude of factors, including clinical, paraclinical and patient-related parameters.
Paludan et al. (Mon,) studied this question.