Free flaps are at their most vulnerable during the first 72 hours after operation, and most compli-cations arise during this period. Things can go wrong later, but they do so sufficiently rarely that the first 3 days can be regarded as the dan-ger period when observation should be most acute. Complications arising more than 3 days postoperatively tend to carry a bad prognosis, and appear to be little affected by surgical intervention.
The postoperative course of a successful free
flap is not unlike that of a successful pedicled flap. Oedema is usual after 24-48 hours and it begins to settle after 72 hours. Transitory oedema is normal in pedicled random pattern flaps, but it is less marked than in the average free flap. Satisfactory progress is indicated by a flap with a definite pink colour, blanching on pressure,
not unlike a healthy random pattern flap.
Deviation from this pattern should give rise to suspicion that an anastomosis is not functioning properly.
A flap which looks ‘collapsed and empty’, fails to blanche on pressure and feels cold, is almost certainly suffering from arterial insufficiency, due either to spasm or thrombosis.
These are dis-tinguished clinically by stabbing the flap with a wide-bore hypodermic needle -if spasm is pres-ent, some bleeding will be seen, although reduced in quantity, but no bleeding occurs if the vessel is thrombosed. The distinction is essentially academic, arterial spasm almost invariably progressing to thrombosis at the anastomosis.
Excessive swelling of the flap, cyanosis, cool-ness, and venous stasis on pressure are indica-tive of venous thrombosis or insufficiency.
Venous problems are much commoner than arterial problems.
Various attempts have been made to provide an objective continuous assessment of the cir-culatory state of free flaps, using plethysmo-graphy in its various forms, Doppler ultrasound, temperature, and percutaneous oxygen tension measurements. None of these are entirely satisfactory, and they can, in fact, be misleading.
The decision as to whether the anastomosis needs to be revised is essentially a clinical one, and the rule is simple. When in doubt, re-explore. Flaps do not suffer as a result of re-exploration.
It is postponement of exploration and revision in the forlorn hope of spontaneous improve-ment which prejudices the survival of the flap, and may convert probable into inevitable flap loss.
The use of pharmaceutical agents to help maintain patency of the anastomoses and good perfusion of the flap has been described. Despite their theoretical virtues, little convincing evid-ence has been produced that they reduce the incidence of thrombosis.
In the heyday of the tube pedicle a comparable pharmaceutical approach was recommended in the generally vain efforts to rescue the failing flap. With pedi-cled flaps the solution lay in designing safer flaps; with free flaps the solution lies in good anastomotic technique.