The muscle twitch monitor: a rapid unequivocal method of monitoring free muscle transfers

[Postoperative monitoring of free muscle flaps using perforator-based adipocutaneous skin paddles: economy, quality of care and aesthetics]

INTRODUCTION

Besides fasciocutaneous workhorse flaps, free muscle flaps for the reconstruction of large soft tissue defects are well-established standard microsurgical procedures. Random-pattern adipocutaneous skin paddles are often included for postoperative perfusion monitoring of the muscle flap. At our institution, both conventional broad-based and perforator-based adipocutaneous skin paddles are used. While conventional skin paddles have to be removed during a second operation, perforator-based skin paddles can be removed at the bedside by ligature. The present study aims to compare economic aspects, quality of care and aesthetic results of perforator-based versus conventional adipocutaneous skin paddles after free muscle flap transfer.

METHODS

102 patients treated between August 2014 and July 2016 were identified and included in a retrospective data analysis. Patients with perforator-based skin paddles (group A) were compared with a population of patients with conventional skin paddles (group B). Patient characteristics, procedural characteristics, economic data and aesthetic results were compared between both groups.

RESULTS

Perforator-based skin paddles were raised in 72 patients (group A, 71 %), and conventional skin paddles were raised in the remaining 30 patients (group B, 29 %). Patient, defect, and flap characteristics were comparable in both groups. Operating times tended to be shorter in group B. Skin paddle removal was performed significantly earlier in group A (p < 0.01). Both overall and post-reconstructive length of hospital stay were significantly shorter in group A (p = 0.03; p < 0.01). Also, personnel and material resources were saved and more satisfactory aesthetic results were achieved in group A.

CONCLUSION

Perforator-based monitor islands can help avoid secondary operations that would otherwise be necessary to remove monitoring skin paddles. Thus, the inpatient length of stay can be reduced while sparing material and human resources.

Random-pattern versus perforator-based adipocutaneous skin paddles for postoperative monitoring of free muscle flaps-a comparative retrospective cohort study

INTRODUCTION

Free microvascular muscle flaps represent well-established reconstructive options for complex soft tissue defects. However, due to their lack of cutaneous capillary beds, they are difficult to monitor postoperatively. To this end, random and axial-pattern adipocutaneous skin paddles are often included. The objective of the study was to compare the impact of random-pattern versus perforator-based adipocutaneous skin paddles on operative efficacy and muscle flap safety.

METHODS

Between August 2014 and July 2016, a total of 120 free muscle flaps were included in this retrospective monocentric cohort study. Based on their skin-paddle type, they were either grouped into a 'perforator-based' (group Pb) or 'random-pattern' (group Rp) cohort. The electronic medical records and operative reports of all patients were subsequently reviewed and patient, defect, and flap characteristics of both groups were compared. The effect of the competing skin paddle types on the overall operative time, incidences of flap loss or microvascular complications, and total length of hospital stay were then assessed.

RESULTS

Group Pb comprised 72 flaps, whereas 48 flaps constituted group Rp. Patient, defect, and flap characteristics were similar between both groups. Groups Pb and Rp were comparable regarding patient age (group Pb: 61 (10-90) vs. Rp: 59 (13-81), p = 0.556), ASA (American Society of Anesthesiologists) class (group Pb: 3 (1-4) vs. Rp 3 (1-3), p = 0.977), and comorbidities, summarized by the Charlson comorbidity index (CCI; group Pb: 1 (0-4 vs. Rp: 1 (0-5), p = 0.295). Both types of monitoring skin paddles were equally reliable. There was no significant difference in the mean operation time between both groups (group Pb: 373 ± 122 min vs. Rp: 342 ± 84 min, p = 0.124). In-patient treatment after flap surgery and total length of hospital stay were significantly shorter in group Pb (group Pb: 24 ± 10 days vs. Rp: 32 ± 17 days, p = 0.002 and group Pb: 39 ± 15 vs. Rp: 48 ± 24, p = 0.022).

CONCLUSION

Perforator-based skin paddles are a reliable tool for postoperative perfusion monitoring of free muscle flaps and help avoid additional surgical interventions as opposed to their random-pattern counterparts. Thus, the overall and postoperative length of hospital stay is significantly reduced.

Effectiveness of small monitoring skin paddle in free muscle flap for scalp reconstruction

BACKGROUND

Monitoring free muscle flaps with skin grafts is difficult. To intensify the monitoring process for this type of flap, a small skin paddle was included in the flap and analyzed its effects.

METHODS

A retrospective analysis of all patients who underwent scalp reconstruction with a free latissimus dorsi flap and skin graft between 1994 and 2016 was conducted. Flap monitoring was proceeded using a combination of clinical examination and handheld Doppler for both types of flaps.

RESULTS

A total of 71 patients were included in this study and were divided into a study group (skin paddle included; n = 30) and a control group (conventional method; n = 41). The time between initial surgery to pedicle exploration was significantly shorter in the study group (11.3 ± 2.5 vs 79.8 ± 42.6 hours; P = .024). The flap salvage rate was significantly higher in the study group (100% vs 16.7%; P = .048).

CONCLUSION

The efficacy of flap monitoring and flap salvage outcomes were improved by including a small monitoring skin flap.

Review of monitoring free muscle flap transfers in reconstructive surgery: role of 99mTc sestamibi scintigraphy

BACKGROUND

Free tissue transfer is a method of moving any tissue from a donor area of the body to a recipient site and re-attaching the arteries and veins to the blood vessels at the recipient site by microvascular surgery. Improved microsurgical techniques have resulted in a high percentage of successful free tissue transfers. Post-operative monitoring of tissue viability can detect early problems in free tissue transfer which may allow early intervention and salvage. Although many flap monitoring methods have been described, there is still no consensus on which of these techniques will become the standard accepted method for monitoring free muscle flaps.

OBJECTIVE

In present study, we investigated the use of 99mTc sestamibi scintigraphy in determining free muscle flap viability and complications, and also in directing treatment.

METHODS

Thirteen patients were examined prospectively during the post-operative period after free tissue transfer for foot defects. The cause of the defect was diabetic foot ulcer in 10 patients, dermatofibrosarcoma in one patient, squamous cell carcinoma in one patient and gunshot wound in one patient. Foot defect covering was carried out with a free latissimus dorsi muscle flap and skin graft (n=12) and a free gracilis muscle flap (n=1). All patients were examined with a monitoring system that consisted of visual inspection, hand-held Doppler ultrasonography and scintigraphic examinations. Scintigraphic imaging of all cases was performed routinely within the first 48 h post-operatively, and also on days 10 and 91 in two patients.

RESULTS

There were four flap failures during the study. One of these patients had viable findings upon visual inspection and no evidence of vascular compromise on Doppler at the first examination. In the other patient, visual inspection of the flap showed that it was ischaemic in one region, but there was no vascular compromise on Doppler examination. Scintigraphic images of each of these patients showed a partial hypoperfused area in the flap region. Later, these two flaps showed positive clinical indications of hypoperfusion (colour of muscle and appearance of skin graft) and Doppler abnormalities. The remaining two patients had non-viable scintigraphic images as well as positive clinical indicators of hypoperfusion and evidence of vascular compromise on Doppler. Nine patients each had a viable flap. In these patients, all three examination tools demonstrated that the flaps were totally viable and there were no vascular complications.

CONCLUSION

According to the results of this study, 99mTc sestamibi scintigraphy appears to be a feasible and promising method in the evaluation of free muscle flap viability and complications. On the other hand, to demonstrate any impact on management or patient outcome, further evaluation of 99mTc sestamibi imaging, including comparative studies with different established methods in a larger patient population, is highly recommended.

Free flap monitoring using an implantable Doppler probe

Although clinical observation is the gold standard, the ideal free flap monitoring device has not been identified. The purpose of the present study was to review the first 14 months of experience using an implantable 20-MHz ultrasonic Doppler probe to monitor the microvascular anastamoses of free tissue transfers. Twenty-five flaps in 23 patients, with an average age of 51 years (age range 18 to 81 years), were performed. Probes were secured downstream of the venous anastamosis using a silicone-poly fluorotetraethylene sleeve. Doppler sounds were transduced before the flap was inset. Monitoring by nursing staff included conventional techniques (temperature, colour, capillary refill) and continuous Doppler flow monitoring. Dynamic diagnostic testing for anastomotic patency was facilitated by applying manual pressure on the flap to increase venous flow (the audible ‘whoosh’ sign) and valsalva manoeuvre to impede venous return momentarily (the ‘heave’ sign). Intraoperative vessel kinking, hematoma formation occluding venous outflow, and venous thrombosis were detected in four cases before concluding the procedure and corrected. Rapid, immediate cessation of audible flow was detected postoperatively in three of 25 flaps. Re-exploration (re-exploration rate 12%) led to salvage of all three flaps (salvage rate 100%). It was concluded from this study that flap re-exploration was prevented in four cases (16%) because of intraoperative use of the implantable Doppler probe. Earlier detection of flap compromise perioperatively is thought to have contributed to the 100% salvage rate and to the 100% flap survival rate in the first 25 cases in which the implantable Doppler probe was used.

Near infra-red spectroscopy: a non-invasive monitor of perfusion and oxygenation within the microcirculation of limbs and flaps

Reliable early detection of adverse circulatory changes within a flap following free tissue transfer and early re-exploration are vital to minimise flap failure. Most surgeons rely on clinical assessment to monitor these changes but techniques such as plethysmography and laser Doppler have their advocates. These methods are limited however to measuring changes close to the surface. Near infra-red spectroscopy (NIRS) is a relatively new, non-invasive technique which allows continuous monitoring of concentration changes in oxy-, deoxy- and total haemoglobin (HbO2, Hb and HbT), as well as oxidised cytochrome aa3, through tissue up to 10 cm in depth. Information is provided on tissue oxygen supply, cellular oxygen utilisation, blood volume and perfusion status. A study has been performed in 10 rabbit hind limbs to assess the ability of NIRS to detect and distinguish between venous, arterial and total vascular occlusion. Clear patterns of change have been identified which allow rapid detection of vascular occlusion with accurate prediction of site. Arterial occlusions were characterised by an increase in Hb with a corresponding decrease in HbO2 and HbT. Venous occlusions resulted in an increase in HbT with relatively minor fluctuations in Hb and HbO2. Simultaneous occlusion of both artery and vein produced similar changes to those of arterial occlusion except that HbT decreased only minimally. These findings suggest that NIRS has a potentially useful role in the monitoring of free flaps, with the great advantage that perfusion can be measured to a considerable depth and information provided on the oxygenation profiles both accurately and non-invasively.

Techniques of postoperative blood flow monitoring after free tissue transfer: an overview

Ever since free tissue transfer has been established in microsurgery, success rates have greatly improved over the years, partly due to improved technical performance of microvascular anastomoses with better optical and instrumental aids. However, flap failure still occurs in 5-10%, mainly due to blood vessel thrombosis within the first 24 postoperative hours. Salvation rates of failing free tissue transfers can be optimized by in-time diagnosis of irreversibly compromised tissue blood flow and immediate operative reexploration. Therefore, there is a special demand for adequate and reliable postoperative monitoring techniques. This article gives an overview of all monitoring techniques, which have been performed both in the experimental and clinical setting thus far.

Tissue oxygen tension measurement for monitoring musculocutaneous and cutaneous flaps

In pigs, latissimus dorsi musculocutaneous island flaps and buttock skin island flaps were raised. Subcutaneous (PscO2) and intramuscular oxygen tension (PimO2) were measured using a non-heated needle electrode before, during and after repeated occlusion of the supplying artery or the draining vein. During arterial and venous occlusion, the tissue oxygen tension in the musculocutaneous flap dropped rapidly. A plateau was reached after 15 min. After arterial occlusion the mean value was 20 mmHg (SEM = +/- 5 mmHg, N = 6) in the subcutis and 16 mmHg in the muscle (SEM = +/- 4 mmHg, N = 10). After venous occlusion the mean value was 11 mmHg (SEM = +/- 3 mmHg, N = 6) in the subcutis. In the skin flap the drop of PscO2 was slower, and after 30 min of arterial occlusion the mean value was 29 mmHg (SEM = +/- 9 mmHg, N = 6). This study has shown that tissue oxygen tension measurement can be used as a sensitive indicator of acute impairment of the supplying vessels in island flaps. The method seems to have potential for monitoring free tissue transfers. A comparable decrease in PscO2 was found for arterial and venous impairment.