CONTINUOUS PERIOPERATIVE MONITORING OF MICROCIRCULATORY BLOOD-FLOW INPECTORALIS MUSCULOCUTANEOUS FLAPS

Hypovolemia and hypotension in traumatized patients as well as those u ndergoing long-lasting surgical procedures lead to hypoperfusion of ti ssues, Combined with the trauma of flap elevation and the warm ischemi a during performance of the anastomoses, hypoperfusion of flap tissues may lead to flap failure, The influence of hypovolemia, ischemia and reperfusion on flap macro- and microcirculation was studied in an acut e experiment on a new musculocutaneous pectoralis flap developed in mi nipigs. Using a multichannel laser Doppler system we studied, simultan eously and continuously, microcirculatory flow (MBF) in both the skin and muscle of the flap as well as in the contralateral control skin an d muscle in anesthetized minipigs (n=7), Measurements were done before and after raising the flap, after 90 min of flap ischemia, during mil d to moderate hypovolemia (5%, 10%, 15%, and 20% blood loss) and durin g and after restoration of blood volume. Electromagnetic flowmetry was used to measure total blood flow (TBF) to the flap, All animals remai ned hemodynamically stable during the experiment, The flap MSF decreas ed by 20% in the skin and 25% in the muscle after flap elevation with no changes in the control skin and muscle. After flap ischemia and rep erfusion, MBF returned to post-elevation values while TBF showed a sig nificant increase as compared to MBF (P<0.05). Hypovolemia caused a gr adual drop in cardiac output (25%) and mean arterial pressure (40%), b ut both recovered above the baseline after reinfusion of shed blood. H ypovolemia also caused a 60% reduction in MBF in both flap skin and mu scle, and only 20-23% in control skin and muscle (P<0.01), After reinf usion of shed blood the MBF in the flap remained 30-40% below and the TBF increased 20% over the baseline. The MBF in control skin and muscl e increased more than 20% over baseline (P<0.01). It was concluded tha t MBF in flap skin and muscle decreased by approximately 20-25% as a c onsequence of flap elevation, while central parameters remained normal . It was shown that even during moderate hypovolemia, MBF in the flap might decrease to critical levels, We suggest that intensive monitorin g of central hemodynamics and continuous LDF monitoring of the flap du ring and after surgery should be performed in order to restore the blo od volume expeditiously and prevent irreversible damage to flap tissue s. (C) 1995 Wiley-Liss, Inc.