Dermal Microcirculation of the Free TRAM Flap Following Adverse Drug Reaction

The free transverse rectus abdominis myocutaneous (TRAM) flap is a popular technique for autologous breast reconstruction.[1] Ongoing study and increasing understanding of the anatomy of the microcirculation in the lower abdominal wall, the umbilicus, and of flaps in general has allowed surgeons to refine their TRAM flap techniques. Few studies however, have been able to assess free flap microcirculation over longer periods - e.g., in the months following surgery. We present the case of a patient who sustained an adverse drug reaction 9 months following free TRAM flap breast reconstruction which enabled us to visualize the distinct microvascular territories in the free TRAM flap and in the donor area.

A 45-year-old female patient was admitted to our plastic surgery unit for revision surgery to her right breast. Nine months earlier she had undergone successful free TRAM flap reconstruction of the right breast. The intended surgery included scar revision to the inframammary crease, and nipple reconstruction of the right breast, as well as reduction mammaplasty to the left breast. At induction of general anesthesia, she developed a profound hyperemia of the skin. The anesthesiologist thought that the most likely drug responsible for the skin flushing was the non-depolarizing muscle relaxant Atracurium. The patient was monitored for other signs of allergy (including hypotension, tachycardia, and bronchospasm), none of which occurred.

Of note to the surgical team waiting to commence the operation was the rapid onset of skin flushing to the patients' entire body, except the area of the TRAM flap and the abdominal skin surrounding the umbilicus (Fig. [1]). The hyperemia slowly developed in the TRAM flap and abdominal skin over approximately 5 min, but within another 5 min, all of the patients' skin had returned to normal. No other signs of allergy occurred and the proposed surgery was carried out without complication. The patient made an uneventful recovery and was discharged home the following day. She remains extremely happy with her breast reconstruction.

Figure 1 Intense dermal vasodilation following adverse drug reaction, but with sparing of the TRAM flap and donor area around the umbilicus.

For the induction of general anesthesia, it is customary to use an intravenous anesthetic (e.g., Propofol), a potent short-acting opioid analgesic (e.g., Fentanyl), and a muscle relaxant (e.g., Atracurium.) Of these drugs, non-depolarizing muscle relaxants (such as Atracurium) are the most likely to be associated with histamine release and skin flushing during anesthesia.[2]

In our patient, following the administration of the Atracurium, the allergic response resulted in widespread histamine release and a profound vasodilation of the dermal vasculature. In the free TRAM flap supplied by a single artery and vein, there was a significant delay in the histamine response, and thus a marked delay (and less severe) hyperemia was seen. Similarly, the area of skin surrounding the umbilicus failed to become hyperemic with the rest of the skin because it too had a reduced blood supply.

Cadaver studies have demonstrated that the skin of the lower abdomen is supplied not only by the deep inferior epigastric vessels, but also the deep inferior epigastric perforator artery, and the superficial inferior epigastric artery.[3] Other cadaver studies have warned of vascular compromise to the abdominal flap following TRAM flaps or abdominoplasty, particularly around a narrowly dissected umbilicus.[4] Our patients' case has shown in vivo what has been postulated by anatomic studies. Visualizing the delayed (and incomplete) hyperemia of the abdominal skin flap surrounding the umbilicus confirms that blood flow to these flaps remains reduced for a significant period of time following surgery.

The circulation of TRAM flaps has been well studied.[5] In pedicled and free TRAM flaps, both laser Doppler flowmetry and transcutaneous oxygen tension have been shown to be reduced up to 10 days following surgery.[6] While it may be postulated that the dermal circulation in the months following TRAM surgery may return to normal, our case suggests this is not so. That the skin of TRAM flaps does not exhibit such brisk blood flow should be remembered by surgeons and patients contemplating revisional surgery to TRAM flaps.

Pharmacologic modification of blood flow in flaps has been suggested as a means of improving the microcirculation of flaps. Of interest, while the selective phosphodiesterase V inhibitor Sildenafil has been shown to increase flap survival in random pattern flaps,[7] the use of prostacyclin and related drugs has not shown demonstratable effects on increasing the perfusion of free flaps.[8] Our case suggests that this is not entirely surprising, as the dermal vasculature of free flaps is relatively resistant to circulating vasodilators.

REFERENCES

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• 2 British National Formulary .British Medical Association and Royal Pharmaceutical Society of Great Britain. London; January 2005
• 3 Reardon C M, Ceallaigh S O, O'Sullivan S T. An anatomical study of the superior inferior epigastric vessels in humans.  Br J Plast Surg. 2004;  57 515-519
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• 7 Knight K R, Crabb D J, Niall M, Angus J A, Martin T J, O'Brien B M. Pharmacologic modification of blood flow in the rabbit microvasculature with prostacyclin and related drugs.  Plast Reconstr Surg. 1985;  75 692-702
• 8 Sarifakioglu N, Gokrem S, Ates L, Akbuga U B, Aslan G. The influence of sildenafil on random skin flap survival in rats: an experimental study.  Br J Plast Surg. 2004;  57 769-772