Continuous free-flap monitoring with tissue-oxygen measurements: three-year experience.

Early recognition of flap failure is a prerequisite for flap salvage. Many methods are used to monitor free flaps. The time interval for re-establishing vascular patency is the limiting factor for a successful revision. Prompt re-operation and a rapid and sufficient correction of the microvascular anastomosis are necessary to maintain flap viability. The Licox Catheter pO 2 Micro-Probe instrument is used for continuous determination of oxygen partial pressure (pO 2 ) in body fluids and tissue (p ti O 2 ). Over a period of 3 years, 60 free tissue transfers to head and neck, trunk, and upper and lower extremities were monitored using the Licox Catheter Probe System. The flexible Licox Catheter pO 2 Micro-Probe detected circulatory changes and failure in all cases, with no false positives or negatives. In all cases in which the arterial pedicle failed, the p ti O 2 dropped rapidly; in cases of venous insufficiency, the p ti O 2 value decreased more or less slowly. In all failing flaps, a p ti O 2 decrease of 10 mmHg within a half-hour, or a p ti O 2 drop below 10 mmHg was observed. These are observations which are useful as precise indicators for vascular complications and flap failure. Based on the authors' observations and data, the Licox probe is a sensitive and accurate monitoring system for all types of free flaps.