Evaluation of Blood Flow in Free Microvascular Flaps

ABSTRACT

Free flap surgery is routine today, yet little is known of its pathophysiology. In this study, the authors evaluated the hemodynamics in different types of free microvascular flaps, by measuring intraoperative transit-time flow. Eighty-six free transplants-21 free TRAM flaps for breast reconstruction, 18 radial forearm flaps for head and neck reconstructions, and 47 muscle flaps for head and neck, trunk and lower extremity reconstructions-were studied. Donor artery flow was highest in the radial artery (mean: 57.5 ± 50 (SD) ml/min) but dropped (p < 0.001) to one tenth (6.1 ± 2 ml/min) after anastomosis. The flow was lowest (4.9 ± 3 ml/min) in the recipient artery of the TRAM flap but, after anastomosis, increased significantly (13.7 ± 5 ml/min) to the level of the flow in the donor artery. The donor-artery flow in muscle flaps had a mean of 15.9 ± 11 ml/min, and it significantly increased after anastomosing (23.9 ± 12 ml/min). Weight-related intake of blood was highest in the radial forearm flap (18.5 ± 6 ml/ min/100g) and lowest in the TRAM flap (2.5 ± 1 ml/min/100g).

The study showed that blood flow through a free microvascular flap does not depend on recipient artery flow. Even low-flow arteries can be used as recipients, because the flow increases according to free-flap requirements. The blood flow through a free microvascular flap depends on the specific tissue components of the flap.

KEYWORD

Free flap - blood flow - transit-time flow - microvascular flap - TRAM

REFERENCES

• 1 Wechselberger G, Rumer A, Schoeller T. Free-flap monitoring with tissue-oxygen measurements.  J Reconstr Microsurg . 1997;  13 125
• 2 Machens H G, Mailander P, Pasel J. Flap perfusion after free musculocutaneous tissue transfer: the impact of postoperative complications.  Plast Reconstr Surg . 2000;  105 2395
• 3 Udesen A, Lontoft E, Kristensen S R. Monitoring of free TRAM flaps with microdialysis.  J Reconstr Microsurg . 2000;  16 101
• 4 Salmi A, Tukiainen E, Asko-Seljavaara S. Thermographic mapping of perforators and skin blood flow in the free transverse rectus abdominis musculocutaneous flap.  Ann Plast Surg . 1995;  35 159
• 5 Yuen J C, Feng Z. Monitoring free flaps using the laser Doppler flowmeter: five-year experience.  Plast Reconstr Surg . 2000;  105 55
• 6 Salmi A M, Tierala E K, Tukiainen E J. Blood flow in free muscle flaps measured by color Doppler ultrasonography.  Microsurgery (Asian issue) . 1995;  16 666
• 7 Lorenzetti F, Salmi A, Ahovuo J. Postoperative changes in blood flow in free muscle flaps: a prospective study.  Microsurgery . 1999;  19 196
• 8 Lundell A, Bergqvist D. Intraoperative flow measurements in vascular reconstructions.  Ann Chir Gynaecol . 1992;  81 187
• 9 Alback A, Makisalo H, Nordin A. Validity and reproducibility of transit time flowmetry.  Ann Chir Gynaecol . 1996;  85 325
• 10 Laustsen J, Pedersen E M, Terp K. Validation of a new transit time ultrasound flowmeter in man.  Eur J Vasc Endovasc Surg . 1996;  12 91
• 11 Walpoth B H, Aufdermauer P, Falleger B. Assessment of intra-operative transit time flow and resistance before and after carotid thrombendarterectomy. In: Proceedings of the First Meeting of the European Society of Neurosonology and 10th International Symposium on Cerebral Hemodynamics. Munchen, Germany, August 29-September 1, 1996
• 12 Lundell A, Bergqvist D. Prediction of early graft occlusion in femoropopliteal and femorodistal reconstruction by measurement of volume flow with a transit time flowmeter and calculation of peripheral resistance.  Eur J Vasc Surg . 1993;  7 704
• 13 Walpoth B H, Mohadjer A, Gersbach P. Intraoperative internal mammary artery transit-time flow measurements: comparative evaluation of two surgical pedicle preparation techniques.  Eur J Cardiothorac Surg . 1996;  10 1064
• 14 Nieminen T, Asko-Seljavaara S, Suominen E. Free microvascular TRAM flaps: report of 185 breast reconstructions.  Scand J Plast Reconstr Surg Hand Surg . 1999;  33 295
• 15 Drost C J. Vessel diameter-independent volume flow measurements using ultrasound.  Proceedings of the San Diego Biomedical Symposium . 1978;  17 299
• 16 Lundell A, Bergqvist D, Mattsson E. Volume blood flow measurements with a transit time flowmeter: an in vivo and in vitro variability and validation study.  Clin Physiol . 1993;  13 547
• 17 Khouri R K. Avoiding free flap failure.  Clin Plast Surg . 1992;  19 773
• 18 Rieck B, Mailänder P, Machens H G. Vascular complications after free tissue transfer.  Microsurgery . 1995;  16 400
• 19 Chen L E, Seaber A V, Bossen E. The effect of acute denervation on the microcirculation of skeletal muscle: rat cremaster model.  J Orthop Res . 1991;  9 266
• 20 Siemionow M, Andreasen T, Chick L. Effect of muscle flap denervation on flow hemodynamics: a new model for chronic in vivo studies.  Microsurgery . 1994;  15 891
• 21 Wang W Z, Anderson G, Firrell J C. Arteriole constriction following ischemia in denervated skeletal muscle.  J Reconstr Microsurg . 1995;  11 99
• 22 Lorenzetti F, Tukiainen E, Asko-Seljavaara. Intraoperative evaluation of blood flow in free LD muscle flaps. Proceedings of the Fourth European Conference of Scientists in Plastic Surgery (ECSPS). Paris, France, October 27-28, 2000
• 23 Hartman J C, Olszanski D A, Hullinger T G. In vivo validation of a transit-time ultrasonic volume flow meter.  J Pharmacol Toxicol Methods . 1994;  31 153
• 24 Matre K, Birkeland S, Hessevik I. Comparison of transit-time and Doppler ultrasound methods for measurement of flow in aortocoronary bypass grafts during cardiac surgery.  Thorac Cardiovasc Surg . 1994;  42 170