Postoperative changes in blood flow in free muscle flaps: a prospective study

Radical Tumor Denervation Activates Potent Local and Global Cancer Treatment

This preliminary study seeks to determine the effect of R&P denervation on tumor growth and survival in immunocompetent rats bearing an aggressive and metastatic breast solid tumor. A novel microsurgical approach was applied "in situ", aiming to induce R&P denervation through the division of every single nerve fiber connecting the host with the primary tumor via its complete detachment and re-attachment, by resecting and reconnecting its supplying artery and vein (anastomosis). This preparation, known as microsurgical graft or flap, is radically denervated by definition, but also effectively delays or even impedes the return of innervation for a significant period of time, thus creating a critical and therapeutic time window. Mammary adenocarcinoma cells (HH-16.cl4) were injected into immunocompetent Sprague Dawley adult rats. When the tumors reached a certain volume, the subjects entered the study. The primary tumor, including a substantial amount of peritumoral tissue, was surgically isolated on a dominant artery and vein, which was resected and reconnected using a surgical microscope (orthotopic tumor auto-transplantation). Intending to simulate metastasis, two or three tumors were simultaneously implanted and only one was treated, using the surgical technique described herein. Primary tumor regression was observed in all of the microsurgically treated subjects, associated with a potent systemic anticancer effect and prolonged survival. In stark contrast, the subjects received a close to identical surgical operation; however, with the intact neurovascular connection, they did not achieve the therapeutic result. Animals bearing multiple tumors and receiving the same treatment in only one tumor exhibited regression in both the "primary" and remote- untreated tumors at a clinically significant percentage, with regression occurring in more than half of the treated subjects. A novel therapeutic approach is presented, which induces the permanent regression of primary and, notably, remote tumors, as well as, evidently, the naturally occurring metastatic lesions, at a high rate. This strategy is aligned with the impetus that comes from the current translational research data, focusing on the abrogation of the neuro-tumoral interaction as an alternative treatment strategy. More data regarding the clinical significance of this are expected to come up from a pilot clinical trial that is ongoing.

Blood flow analyses by intraoperative transit-time flow measurements of free flaps for head and neck reconstructions: A prospective single-center study

BACKGROUND

The behavior of blood flow changes within free flaps following microvascular anastomosis is not well described in the literature. The aim of this study was to determine the immediate blood flow behavior of different free flaps as reference values for various clinical applications.

METHODS

Intraoperative transit-time flow measurements were performed on patients receiving free flap transfer in the head and neck area comprising radial forearm flaps (RFF), peroneal artery perforator flaps (PAP), anterolateral thigh flaps (ALT), vastus lateralis flaps (VLF), parascapular flaps (PSF), latissimus dorsi flaps (LDF), fibula free flaps (FFF), deep circumflex iliac artery flaps (DCIA), and scapular flaps (SF). In accordance with a structured protocol, measurements took place at the pedicle directly before flap harvesting and at the recipient vessels 1 h after flap transfer. Heart rate, transplant weight, and other patient characteristics were recorded and analyzed.

RESULTS

A total of 129 were enrolled, comprising 66 RFF, 8 ALT, 6 PAP, 11 VLF, 3 PSF, 2 LDF, 24 FFF, 7 DCIA, and 2 SF. In most of the transplant groups, arterial perfusion increased after anastomosis at the recipient site. The arterial pulsatility index developed indirectly proportionally to arterial blood flow, whereas venous blood drainage did not show any statistically significant changes. Muscle flaps had the highest arterial perfusion before flap transfer. Composite transplants with hard and soft tissue presented the greatest increase in arterial perfusion. The lowest arterial blood flow after anastomosis was measured in PAP and RFF. In contrast, RFF and PAP presented the highest arterial perfusion per 100 g transplant weight.

CONCLUSIONS

Arterial perfusion changed, whereas venous blood flow did not show any statistically significant variations in any transplant group. Perfusion of free flaps does not only depend on the recipient vessel and the recipient bed, but also on flap-specific anatomy and physiology.

Comparing the Time-Dependent Evolution of Microcirculation in Gracilis vs. ALT Flaps Using Laser-Doppler Flowmetry and Tissue-Spectrometry

Postoperative free flap monitoring is considered a key component of care after microsurgical reconstruction. To achieve successful flap salvage after surgical revision, early recognition of vascular compromise is required. The aim of this study was to assess and compare the time-dependent evolution of microcirculation in gracilis muscle (GM) and anterolateral thigh (ALT) flaps. This study included continuous measurements of blood flow (flow), hemoglobin oxygenation (SO2) and the relative amount of hemoglobin (rHb) using laser-doppler flowmetry and tissue-spectrometry (O2C, LEA Medizintechnik, Gießen, Germany) over a time-period of 72 h. Microcirculation was assessed in a total of 66 viable free flaps (GM n = 40; ALT n = 26). A statistically significant positive correlation between time post-anastomosis and microvascular flow was found for both GM and ALT flaps with rs = 0.384 (p < 0.001) and rs = 0.178 (p = 0.015), respectively. No significant positive or negative correlations between time post-anastomosis and SO2 were found for both GM and ALT flaps with rs = 0.052 (p = 0.387) and rs = −0.018 (p = 0.805), respectively. Overall, a significant negative correlation between time post-anastomosis and rHb was found for GM flaps with rs = −0.140 (p = 0.019). For ALT flaps, no significant positive or negative correlation was found with rs = −0.011 (p = 0.887). Microcirculation differs in different flap entities, and surgeons should be aware of these differences in order to correctly evaluate and classify the values of flow, SO2 and rHb obtained when using the O2C device for postoperative monitoring.

The 72-Hour Microcirculation Dynamics in Viable Free Flap Reconstructions

BACKGROUND

 The risk for vascular complications is the highest within the first 24 hours after free flap transfer. Clinical signs of critical perfusion are often recognized with time delay, impeding flap salvage. To detect failing flaps as soon as possible and to prevent persisting microvascular impairments, knowledge of physiological perfusion dynamics in free flaps is needed. Aim of this study was to investigate the physiological perfusion dynamics of viable free flaps using the Oxygen to See (O2C) device for continuous monitoring.

METHODS

 Microcirculation was continuously monitored in 85 viable free flaps over a period of up to 72 hours following microvascular anastomosis using tissue spectrophotometry and laser Doppler flowmetry (O2C, LEA Medizintechnik, Gießen, Germany). The parameters investigated included capillary-venous blood flow (flow), oxygen saturation (SO₂), and relative amount of hemoglobin (rHB).

RESULTS

 Microcirculatory blood flow increased significantly overall, especially within the first 18 hours after microsurgical anastomosis, after which peak formation was occurred. Mean values of SO₂ showed a decreasing trend and the steepest decrease of SO₂ (slope: 1.0) occurred during the steepest increase of flow between 3 and 6 hours (slope: 4.7) postanastomosis. The rHB values remained fairly constant throughout the study period.

CONCLUSION

 Hyperemia after free flap transfer accounts for a significant increase of microvascular flow. Tissue oxygenation is reduced, likely due to an increase of oxygen consumption after anastomosis. A better understanding of physiological perfusion dynamics in free flaps can aid surgeons in recognizing compromised vasculature earlier and improve free flap salvage.

Bilateral DIEP Flap Breast Reconstruction to a Single Set of Internal Mammary Vessels: Technique, Safety, and Outcomes after 250 Flaps

BACKGROUND

The deep inferior epigastric artery perforator (DIEP) flap is considered the gold standard in autologous breast reconstruction. In bilateral cases, both flaps are often anastomosed to the internal mammary vessels on either side of the sternum. The authors propose a method in which both flaps are anastomosed to only the right side internal mammary artery and vein.

METHODS

Between November of 2009 and March of 2018, 125 patients underwent bilateral DIEP flap breast reconstruction with this technique. One flap is perfused by the anterograde proximal internal mammary artery and the second one by the retrograde distal internal mammary artery after presternal tunneling. Patient demographics and operative details were reviewed retrospectively.

RESULTS

Two hundred fifty flaps were performed. One hundred fifty-two flaps were prophylactic or primary reconstructions (60.8 percent), 70 were secondary reconstructions (28 percent), and 28 were tertiary reconstructions (11.2 percent). Mean patient age was 46 years, and the mean body mass index was 25 kg/m. Sixty patients underwent radiation therapy or chemotherapy (48 percent). The authors encountered one significant partial failure (0.4 percent) and nine complete flap failures (3.6 percent). The authors did not see a statistically significant predisposition for failure comparing the retrograde with the anterograde flow flaps, nor when comparing the tunneled with the nontunneled flaps.

CONCLUSIONS

The authors' results show that anastomosing both DIEP flaps to a single set of mammary vessels is safe and reliable. The authors conclude that the retrograde flow through the distal internal mammary artery is sufficient for free flap perfusion and that subcutaneous tunneling of a free flap pedicle does not predispose to flap failure.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

MRI anatomical preoperative evaluation of distally based peroneus brevis muscle flap in reconstructive surgery of the lower limb

BACKGROUND

The distally based peroneus brevis muscle flap has proved to be a simple solution for small- to moderate-sized wounds of the lower limb. The length of the muscle belly suitable for coverage is a crucial parameter. In this study, we evaluated the capability of 3D MRI of the lower limb to measure it preoperatively.

METHODS

Between 2008 and 2017, 32 patients with lower limb defects underwent preoperative MRI to measure the peroneus brevis muscle length. All patients underwent reconstruction, and the muscle was measured again intraoperatively during surgical dissection. Surgical measurements were then compared to the MRI ones.

RESULTS

MRI measures of the peroneus brevis muscle belly ranged from 9 to 21 cm (μ = 14.44 ± 3.43 cm), and intraoperative measures ranged from 9 to 20 cm (μ = 14.2 ± 2.3 cm). Thirty of 32 intraoperative measures corresponded to the MRI ones (variation = ± 1 cm, r = 0.92, p = 0.002). One patient showed an intraoperative muscle length 3 cm shorter than the MRI measure, and another patient had intraoperative muscle length 3 cm longer than the MRI one. All flaps survived, and no secondary local flap coverage was required, with no flap-related complication, limited donor site morbidity, and acceptable patient discomfort.

CONCLUSIONS

The reverse peroneus brevis muscle flap is a versatile alternative to free flap reconstruction in small- to moderate-sized defects of the lower limb. Preoperative 3D MRI is accurate to evaluate the anatomy of the muscle when performed by an expert radiologist. In our experience, it should become part of preoperative workup before performing a peroneus brevis flap procedure.

The effects of limited adventitiectomy on vascular anastomosis: An experimental study in rats

OBJECTIVE

Blockages in anastomotic vessels cause complete loss of free tissue transfer and replanted limb. Many studies have been conducted in the last 30 years to solve this problem. There are insufficient studies dealing with the effects of the limited adventitiectomy done before surgery for sympathetic overactivity leading situations. The aim of this experimental study is to reveal the effects of limited adventitiectomy.

METHODS

In this study, limited adventitiectomy was performed in a wide area before surgery, and the effect of this practice on the vessel diameter and anastomosis was investigated.

RESULTS

Rapidly growing dilatation and increase in vessel diameter was observed, and dilatation continued in the limited adventitiectomy group.

CONCLUSIONS

The preoperative performed limited adventitiectomy is a useful preparation for super microsurgery. Especially in clinical practice before the free flap surgery, limited adventitiectomy can be applied if the recipient site is expected to have vascular problems.

Noncontact diffuse optical assessment of blood flow changes in head and neck free tissue transfer flaps

Knowledge of tissue blood flow (BF) changes after free tissue transfer may enable surgeons to predict the failure of flap thrombosis at an early stage. This study used our recently developed noncontact diffuse correlation spectroscopy to monitor dynamic BF changes in free flaps without getting in contact with the targeted tissue. Eight free flaps were elevated in patients with head and neck cancer; one of the flaps failed. Multiple BF measurements probing the transferred tissue were performed during and post the surgical operation. Postoperative BF values were normalized to the intraoperative baselines (assigning "1") for the calculation of relative BF change (rBF). The rBF changes over the seven successful flaps were 1.89 ± 0.15, 2.26 ± 0.13, and 2.43 ± 0.13 (mean ± standard error), respectively, on postoperative days 2, 4, and 7. These postoperative values were significantly higher than the intraoperative baseline values (p<0.001), indicating a gradual recovery of flap vascularity after the tissue transfer. By contrast, rBF changes observed from the unsuccessful flaps were 1.14 and 1.34, respectively, on postoperative days 2 and 4, indicating less flow recovery. Measurement of BF recovery after flap anastomosis holds the potential to act early to salvage ischemic flaps.

Flow-through free latissimus dorsi flap for reconstruction of injured limbs: Evaluation of hemodynamic effects on extremity circulation

Management of vascularized injured extremity requires careful reconstruction for continuity of leg circulation. Protection of the remaining intact vessels during free flap transfer provides condition for blood flow maintenance in the distal extremity. Latissimus dorsi muscle has the correct vessel anatomy for applying flow-through flap because it protects recipient vessel integrity during soft tissue reconstruction. Flow-through flap circulation may cause decreasing blood flow in the recipient artery and steal phenomenon in distal circulation although the main vessel remains intact. The purpose of this study was to describe blood flow changes in the recipient artery, flap pedicle, and distal leg circulation at early and long-term follow- up periods. For this purpose, evaluations of blood flows by using Doppler ultrasonography were performed in 2 vascularized injured extremities which were reconstructed with flow-through free latissimus dorsi musculocutaneous flaps. The results demonstrate that flow-through flaps in our vascularized injured extremity did not disturb distal leg circulation in spite of increased blood flow in the recipient and pedicle arteries.

Changes in blood velocity following microvascular free tissue transfer

Understanding how pedicle blood velocities change after free tissue transfer may enable microvascular surgeons to predict when thrombosis is most likely to occur. A 20-MHz Doppler probe was used to measure arterial and venous blood velocities prior to pedicle division and 20 minutes after anastomosis in 32 microvascular free flaps. An implantable Doppler probe was then used to measure arterial and venous blood velocities daily for 5 days. Peak arterial blood velocity averaged 30.6 cm/s prior to pedicle division and increased to 36.5 cm/s 20 minutes after anastomosis ( P < 0.05). Peak venous blood velocity averaged 7.6 cm/s prior to pedicle division and increased to 12.4 cm/s 20 minutes after anastomosis ( P < 0.05). Peak arterial blood velocities averaged 34.0, 37.7, 43.8, 37.9, 37.6 cm/s on postoperative days (PODs) 1 through 5, respectively. Peak venous blood velocities averaged 11.9, 14.5, 18.2, 16.8, 17.7 cm/s on PODs 1 through 5, respectively. The peak arterial blood velocity on POD 3, and peak venous blood velocities on PODs 2, 3, and 5 were significantly higher than 20 minutes after anastomosis ( P < 0.05). Arterial and venous blood velocities increase for the first 3 postoperative days, potentially contributing to the declining risk for pedicle thrombosis during this time period.

Blood flow autoregulation in pedicled flaps

INTRODUCTION

Clinical work on the blood perfusion in skin and muscle flaps has suggested that some degree of blood flow autoregulation exists in such flaps. An autoregulatory mechanism would enable the flap to protect itself from changes in the perfusion pressure. The purpose of the present study was to evaluate if, and to what extent, a tissue flap could compensate a reduction in blood flow due to an acute constriction of the feed artery. Further, we wanted to examine the possible role of smooth muscle L-type calcium channels in the autoregulatory mechanism by pharmacological intervention with the L-type calcium channel blocker nimodipine and the vasodilator papaverine.

MATERIAL AND METHODS

Pedicled flaps were raised in pigs. Flow in the pedicle was reduced by constriction of the feed artery (n=34). A transit time flow probe measured the effect on blood flow continuously. Following this, three different protocols were followed: (1) Time control (n=10): the procedure described above was repeated in the same flap to determine whether autoregulatory efficiency changed over time. (2) Nimodipine infusion (n=13): continuous intra-arterial infusion of nimodipine (0.2mg/ml, 0.5 ml/min) started when the flow had returned to the initial value. After stabilisation, the flow was reduced. When the flow had been stable for at least 5 min, the constriction was removed. (3) Nimodipine and papaverine (n=8): the infusion of nimodipine was followed by an intra-arterial bolus of papaverine (10mg). After stabilisation, the flow in the pedicle was reduced and the flow was recorded.

RESULTS

The flaps showed a strong autoregulatory response with complete compensation for flow reductions of up to 70-80%. Infusion of nimodipine caused a 28+/-10% increase in blood flow and removed the autoregulation. Papaverine caused a further increase in blood flow by 61+/-19%. The time control experiments proved that the experimental procedure was reproducible and stable over time.

CONCLUSIONS

A tissue flap can nearly completely compensate for repeated flow reductions of up to 70-80%. This is due to a decrease in the peripheral resistance, mediated by a local intrinsic mechanism. Nimodipine (a blocker of L-type voltage-activated calcium channels) abolishes the autoregulation, but a significant vasodilatory reserve exists, as an additional injection of papaverine (a smooth muscle relaxant) results in a further increase in the blood flow. This strongly suggests a direct role for voltage-activated calcium channels in the autoregulatory process.

The haemodynamics of the distal arterial Y-shaped autograft bypass-flap in a porcine experimental model

BACKGROUND

The haemodynamic effects of revascularisation with combined bypass and free-muscle flap remain controversial. In a porcine experimental model, we investigated the transplantation-induced changes in the haemodynamics of a Y-shaped combined arterial autograft bypass-muscle flap (AABF).

METHODS

Anatomy of AABF was identified in eight dissections in four porcine cadavers. In five animals, AABF served as a superficial femoral artery (SFA) defect replacement. Modelled, triggered pulsatile pressure (P) and flow (Q) waves delivered mean haemodynamics and PQ hysteresis loops before and after transplantation at days 0 and 10.

RESULTS

Anatomically, AABF combined subscapular and circumflex-scapular arteries, and thoracodorsal artery as latissimus dorsi flap pedicle. Surgical feasibility and AABF patency were confirmed in each case. At day 0, the proximal flow was increased in the grafted Y-shaped AABF, which also adopted the specific SFA pulsatile haemodynamics. Regulatory mechanisms of AABF vasomotricity were preserved and AABF-flow-dependence amplified the flow in the distal segment, which otherwise preserved its own flow dependence. At 10 days, the AABF flow was unchanged in the distal segment, and remained elevated in the proximal and pedicle segments.

CONCLUSIONS

Combined AABF, as a single one-piece arterial autograft, was shown highly adaptive to the receiving arteries. The transplantation-induced changes in AABF pulsatile flow profile and vascular reactivity improve the overall graft flow, and strongly advocate for beneficial effects on the blood propelling capacity of the grafted circulation.

A study of perfusion of the distal free-TRAM flap using laser Doppler flowmetry

The aim of this study was to characterise microcirculatory changes in the distal part of a flap and to evaluate whether measurement of the microcirculation may predict flap complications (FC). In this prospective study, 30 patients undergoing a delayed breast reconstruction were included. Perioperative data were recorded and with the laser Doppler flowmetry (LDF; Perimed) blood flow was recorded in the central part (zone I) and the distal part (zone IV) of the flap. A lower blood flow was observed in zone IV of patients with flap complications compared to patients without flap complications (P=0.013). In addition, LDF demonstrated different flow trends in zone I compared to zone IV indicating a delayed opening of the choke vessels connecting the angiosomes in the distal part of the flap. The LDF has proven to be a useful investigative tool to monitor microcirculatory changes. In future studies it will be used to evaluate interventions aimed at decreasing distal ischaemia and reducing flap complications.

Blood Perfusion of the Free Anterolateral Thigh Perforator Flap: Its Beneficial Effect in the Reconstruction of Infected Wounds in the Lower Extremity

BACKGROUND

In a prospective study, we evaluated the blood perfusion and the blood flow of anterolateral thigh (ALT) flap by both near-infrared spectroscopy and color Doppler ultrasonography. Moreover, we assessed the ability of the perforator flap to reconstruct infected wounds of the lower extremity in 11 patients.

METHODS

Near-infrared spectroscopy showed excellent oxygen saturation, and Doppler ultrasonography documented excellent blood flow and decreased vascular resistance in the ALT flap postoperatively.

RESULTS

All flaps were successful and all wounds healed uneventfully within 2 weeks without any signs of recurrences or persistent infection. All patients achieved acceptable gait function after rehabilitation.

CONCLUSIONS

Apart from the mandatory role of thorough debridement, our results indicate that the ALT flap offers rich blood supply to the recipient area, thus contributing to the sterilization and healing of an infected wound within a short time period.

Duplex Ultrasound Imaging in Free Transverse Rectus Abdominis Muscle, Deep Inferior Epigastric Artery Perforator, and Superior Gluteal Artery Perforator Flaps

OBJECTIVE

Our objective was to assess the hemodynamic differences in free DIEP (deep inferior epigastric artery perforator flap), S-GAP (superior gluteal artery perforator flap) flaps versus TRAM (transverse rectus abdominis muscle) flaps and to analyze any perfusion change due to perforator dissection (study 1). To examine the hypothesis as to whether flap perfusion is maintained through the pedicle (study 2), we also compared short- and long-term DIEP flap perfusion.

MATERIAL AND METHODS

Blood volume flow, velocity, and diameter of the donor and recipient vessels of 4 TRAM flaps, 5 S-GAP flaps, and 17 DIEP flaps were examined preoperatively on day 5 and also 18 months postoperatively using duplex ultrasound.

RESULTS

The greatest volume flow and velocity are measured in the TRAM flaps, followed by S-GAP and DIEP flaps. Blood flow in the musculocutaneous and perforator flaps is twice as great as in the donor vessels, which is proof of flap hyperperfusion.

SUMMARY

The minimum perfusion requirement is easily satisfied in musculocutaneus and free perforator flaps. In the long term, DIEP flap perfusion increases 13%, which assumes that DIEP flap perfusion is maintained on the pedicle.

The Effect of Intravenous Dopamine and Dobutamine on Blood Circulation During a Microvascular TRAM Flap Operation

A study was conducted to assess the effect of intraoperatively administered inotropic agents on blood flow in the recipient and donor vessels, during breast reconstruction with a muscle sparing free TRAM flap. Twenty-one consecutive patients were randomized into 3 groups receiving either dopamine, dobutamine, or placebo. When the flap and all vessels had been fully dissected but not yet divided, the study drug was administered intravenously for 15 minutes. Hemodynamic parameters and transit-time flow of the thoracodorsal and inferior epigastric arteries were monitored. Both dobutamine and dopamine infusions resulted in significant raises in cardiac output and mean arterial pressure. However, while dobutamine resulted in a higher cardiac output (P = 0.001) and a decrease in systemic vascular resistance (P = 0.028), the increase in mean arterial pressure was greater with dopamine (P = 0.002). Only the dobutamine group showed increased blood flow, in both the thoracodorsal (P = 0.043) and the inferior epigastric (P = 0.043) arteries. If vasoactive agents are needed during microvascular anesthesia, dobutamine seems to be more advantageous than dopamine.

Long-term morphometric and immunohistochemical findings in human free microvascular muscle flaps

Reinnervation, muscle regeneration, density of microvessels, and muscle-type specific atrophy were studied 3-4 years after surgery in surgically nonreinnervated free microvascular muscle flaps to 13 patients transplanted to the upper or lower extremities. Routine histology and immunohistochemistry for PGP 9.5 and S-100 (neuronal markers), Ki-67 (cell proliferation), myosin (muscle fiber types), and CD-31 (endothelium) were carried out, and results were analyzed morphometrically. Three to 4 years after surgery, severe atrophy of predominantly slow-type fibers was seen in 9 cases. In 4 cases, muscle-fiber diameter and fiber-type distribution were close to normal. Long intraoperative muscle ischemia and postoperative immobilization were associated with poor muscle bulk in flaps. The density of microvessels in flaps did not differ from control muscles. PGP 9.5 and S-100 immunopositive nerve fibers were detected in 7 patients. Reinnervation was associated with good muscle bulk. In 4 patients, activation of satellite cells was evident. The results suggest that in some cases, spontaneous reinnervation may occur in free muscle flaps, and that several years after microvascular free flap transfer, the muscle still attempts to regenerate.

Short-term postoperative flow changes after free radial forearm flap transfer: possible cause of vascular occlusion

The risk for free flap thrombosis is greatly influenced by blood flow. Postoperative hemodynamic changes in vascular pedicles of the microvascular skin flap have not been reported, however. This study focuses on the intraoperative and postoperative changes in the flow volume in the vascular pedicles of the free forearm flap examined by color Doppler ultrasonography. The arterial flow volume increased continuously until day 7, compared with which, the volume after flap elevation was 36%. On day 1, it reached only 52%. In the venous pedicle, the flow volume through the cutaneous vein was only 37% compared with that through the radial vena comitans after flap elevation, whereas the volume through both veins was equal on day 7. Drastic changes in the flow explain the possible vascular occlusion during the early postoperative period in the free forearm flap transfer.

Color Doppler ultrasound for monitoring free flaps in the head and neck region

The use of microvascular free flaps has become established as a very reliable reconstructive technique following tumor surgery or trauma in the head and neck region. Occasionally, flap compromise may occur which will require immediate re-exploration. Early diagnosis of vascular insufficiency is essential. Clinical signs are not always reliable. Numerous systems have been described for monitoring the viability of microsurgical free flaps. The authors consider that color Doppler ultrasound is one of the most useful diagnostic tools. Three cases are reviewed in which this technique aided the decision whether re-exploration was necessary.

Blood flow in a pedal bypass combined with a free muscle flap

OBJECTIVE

to assess the haemodynamic effect of a free muscle flap on the midterm success of a pedal bypass.

DESIGN

prospective consecutive study.

MATERIALS

a pedal bypass (autogenous vein graft) combined with a free muscle flap was performed in 13 patients with critical leg ischaemia. The feeding artery of the flap was anastomosed end-to-side to the bypass.

METHODS

blood flow was measured in the bypass before and after transplanting the flap. Doppler was used postoperatively to assess the patency.

RESULTS

the bypass and flap pedicle were patent in 11 cases six months postoperatively. Two grafts were thrombosed and the legs amputated. In the successful group the median (range) blood flow in the bypass was 50 (10-100) ml/min. It increased (p<0.05) after transplantation to 64 (20-113) ml/min, being 44 (14-97) ml/min distributed to the foot. Blood flow through the flap was 20 (6-37) ml/min. The two failing grafts had a flow of 30 and 51 ml/min before and 48 and 52 ml/min after transplantation, respectively. Blood flow through the flap was 47 ml/min and 36 ml/min, respectively. In the failure group the free flap received most of the blood supply through the bypass.

CONCLUSIONS

a free muscle flap connected to an infrapopliteal bypass increases the distal outflow bed and thus decreases the outflow resistance and increases graft flow.