Timing of Presentation of the First Signs of Vascular Compromise Dictates the Salvage Outcome of Free Flap Transfers

Sir: We read with interest the article entitled “Timing of Presentation of the First Signs of Vascular Compromise Dictates the Salvage Outcome of Free Flap Transfers” by Chen et al.1 The authors discuss the favorable influence of an intense monitoring protocol on the outcome of salvage procedures after free flap deterioration. In a recently published study,2 we also evaluated the correlation between the timing of flap compromise and the outcome of the salvage procedure. Our results showed that the mean time interval between initial surgery and salvage procedure in successful revisions was significantly lower than in unsuccessful cases. However, when interpreting these results, the intensity of monitoring should also be regarded. The intensity of monitoring in our study decreased in time and stopped on the seventh day after surgery. In the study by Chen et al., flaps were intensely monitored for the first 5 days after surgery, during which time flaps were monitored every hour. Both studies stress the importance of spotting a complication as soon as possible. Many monitoring strategies differ with regard to timing of various check-ups and the monitoring modality used.3 In search of a more consistent monitoring protocol, the Cook-Swartz probe (Cook Medical, Cook Ireland Ltd., Limerick, Ireland) was introduced in our clinic (Fig. 1).4 It is an implantable 20-MHz probe that consists of an electrode and a cuff. After having performed the anastomoses, the cuff is wrapped around the vein (Fig. 2). The probe exits the body through a thin wire. Outside the body, it is connected to a transportable monitor. On the seventh day after surgery, the probe is pulled externally and the electrode slides free from the cuff (from the fifth day on, the cuff is sufficiently adherent to the vein and the vein adherent to the surrounding tissue to allow safe traction). The probe allows continuous vessel monitoring of the microvascular anastomosis, ensuring real-time information on blood flow from the flap at any time. As such, indirect information about blood flow to the flap can also be retrieved. Since its introduction, the Cook-Swartz probe has become the most important monitoring device in our clinical practice. The main advantage it offers is direct and continuous monitoring of the anastomosis. Its introduction changed the way we monitor free flaps. They are now monitored primarily by the Cook-Swartz probe. Other methods such as hand-held Doppler probes are used only on indication. This makes the monitoring less labor intensive and causes less distress for patients, because they do not have to be awakened at night. We think that the Cook-Swartz probe is a useful and reliable tool in free flap monitoring. By its introduction, we were able to detect vascular complications earlier and reduce patient discomfort.Fig. 1.: The Cook-Swartz probe, showing the cuff and electrode. The cuff will be wrapped around the vein.Fig. 2.: The cuff of the Cook-Swartz probe being wrapped around the vein. Attached to the probe is the wire that leads the signal outside the body. The venous anastomosis can be seen distal from the cuff.Jeroen M. Smit, M.D. Clark J. Zeebregts, M.D., Ph.D. Rafael Acosta, M.D. Department of Plastic and Reconstructive Surgery Uppsala University Hospital Uppsala, Sweden