the restricted content you must first complete our Flaps and replanted tissues will often exhibit large changes in tissue blood flow during the immediate post operative period. Although it is worth monitoring during this time the setting of alarm levels may not be appropriate until after the patient has left the recovery room and has been transferred to the main ward.
When the patient is in this more stable environment, the best use of the alarm auto-set can be made. Alarm levels will be automatically set by the monitor following a 30-minute baseline measurement. A 60% drop from this baseline will trigger the alarm. The alarm level can also be set manually if preferred or values other than 60% chosen as the default.
Laser Doppler (LD) flap monitoring can give warning of flap failures many hours before clinical signs are apparent. Alarm levels should be set relative to baseline flow rather than for 'normal' values. This is because even in the same tissues there are a wide range of values.
Signs of a healthy flap are a pulsatile LD blood flow waveform (on 'FAST' display mode) due to the cardiac cycle and a stable or steadily increasing trend. Fluctuations in LD blood flow are also good signs. These are due to vasomotion and physiological responses.
Signs of a failing flap include lack of pulsatility, a falling trend and lack of fluctuations. Reference gives further guidance on the interpretation of laser Doppler recordings.