A contrivance for monitoring skin flaps with a Doppler flowmeter

[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.

The use of sentinel skin islands for monitoring buried and semi-buried micro-vascular flaps. Part I: Summary and brief description of monitoring methods

Micro-vascular flaps have been used for the repair of challenging defects for over 45 years. The risk of failure is reported to be around 5-10% which despite medical and technical advances in recent years remains essentially unchanged. Precise, continuous, sensitive and specific monitoring together with prompt notification of vascular compromise is crucial for the success of the procedure. In this review, we provide a classification and brief description of the reported methods for monitoring the micro-vascular flap and a summary of the benefits over direct visual monitoring. Over 40 different monitoring techniques have been reported but their comparative merits are not always obvious. One looks for early detection of a flap's compromise, improved flap salvage rate and a minimal false-positive or false-negative rate. The cost-effectiveness of any method should also be considered. Direct visualisation of the flap is the method most generally used and still seems to be the simplest, cheapest and most reliable method for flap monitoring. Considering the alternatives, only implantable Doppler ultrasound probes, near infrared spectroscopy and laser Doppler flowmetry have shown any evidence of improved flap salvage rates over direct visual monitoring.

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.

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 simultaneous non-invasive laser Doppler flowmetry and tissue spectrophotometry

BACKGROUND

Early identification of flap failure is an indispensable prerequisite for flap salvage. Although many methods of free flap monitoring are available, there is still no single reliable non-invasive technique for early recognition of flap failure and for differentiation between arterial occlusion and venous congestion. The aim of this study was to investigate the benefits of the tissue oxygen analysis system O(2)C for monitoring patients undergoing maxillofacial reconstruction with fasciocutaneous radial forearm flaps.

MATERIAL AND METHODS

In a prospective clinical study the microcirculatory parameters of blood flow, flow velocity, haemoglobin concentration (AU, Arbitrary Units) and oxygen saturation (%) were assessed by clinical means, by laser Doppler flowmetry and tissue spectrophotometry in 61 patients intraoperatively. Measurements were carried out before flap harvest, in the separated radial forearm flap, immediately after anastomoses and up to 14 days after reconstruction.

RESULTS

Following anastomosis, blood flow and flow velocity exceeded the level before flap elevation and reached significant differences by the third postoperative day (p<0.05). Oxygen saturation decreased significantly by the third postoperative day and haemoglobin oxygenation showed stable values after performing anastomosis. Simultaneous, non-invasive laser-Doppler flowmetry and tissue spectrophotometry detected vascular complications in all cases with no false positive or false negative results and prior to clinical assessment.

CONCLUSION

For the first time this new device allows reliable prediction of venous congestion by an increase of haemoglobin-concentration, and of arterial occlusion by a decrease in blood flow parameters and oxygen saturation. It can thus differentiate the mechanisms of flap failure before clinical assessment.

Simultanes nichtinvasives Monitoring mit Laser-Doppler-Flussmessung und Gewebespektrometrie bei fasziokutanen Radialislappen und osteokutanen Fibulatransplantaten

AIM

In the literature currently available monitoring devices are usually divided into two major groups: those for monitoring perfusion and those for measuring tissue oxygenation. The O(2)C (oxygen to see) system combines these two ways of monitoring free flap viability. The aim of this prospective study was to determine the necessity of flap revision and when unnecessary revision can be avoided. Another point of interest was the question of whether critical values for the successful course of free flaps could be defined and in addition whether such values would differ for different flap types.

PATIENTS AND METHODS

In a prospective study 82 free flaps (61 radial forearm flaps and 21 fibula flaps) were monitored with the O(2)C monitoring unit. Measurements were carried out intraoperatively and postoperatively up to 14 days.

RESULTS

Perfusion compromise occurred in 12 (14.6%) of 82 monitored free flaps. Operative exploration was performed in seven cases, in five of them successfully. Five flaps (three radial forearm and two fibula flaps) were lost due to vascular compromise, which led to an overall success rate of 93.4%. Venous congestion was identified by a rapid increase in hemoglobin concentration of more than 30%. An abrupt decline of blood flow and hemoglobin oxygenation indicated arterial occlusion. Vascular complications were detected in all cases prior to clinical assessment with no false positive or negative results. For radial forearm flaps a hemoglobin oxygenation of 15%, a superficial flow of 10 AU, and a deep flow of 20 AU were identified as minimum values for flap viability. For fibula flaps a hemoglobin oxygenation of 10%, a superficial flow of 5 AU, and a deep flow of 15 AU were determined as minimum values.

CONCLUSION

O(2)C combines laser Doppler flowmetry and tissue spectrophotometry and for the first time allows simultaneous measurement of the microcirculatory parameters including blood flow, flow velocity, hemoglobin concentration, and hemoglobin oxygenation. We found this new noninvasive technique to be a reliable and accurate method for evaluating flap viability and improving the success rate in free flap transfer.

Laser Doppler flowmeter monitoring of free-tissue transfers: blood flow in normal and complicated cases

In this article, laser Doppler flowmeter (LDF) monitoring of blood flow in 94 free flaps is summarized. Seventy-six patients had uneventful postoperative courses, and 18 patients developed postoperative complications, with a salvage rate of 88 percent. Except for one case, the flowmeter identified developing complications before clear clinical indices appeared, and in two cases it was the only indication of vascular compromise of the flap. On the basis of the data obtained, the ranges of absolute flow values in different types of uncomplicated flaps are reported, along with their temporal pattern of flow. Decrease inflow pattern may be an early indicator of a developing perfusion disturbance. On the basis of LDF readings, the following classifications of free-flap blood flow are suggested. (1) If the flow is within or slightly above the established range, then normal diligence in observation is justified. If the flow is well above the normal range, artifacts that could falsely elevate readings should be investigated. (2) If the flow is somewhat below the established range, then a modest increase in observation is warranted (alert level 1). (3) If the relative flow falls to 50 percent of the initial flow of that flap and remains at that level for 30 minutes or longer, then more aggressive flap observation is indicated (alert level 2). (4) If the flow is below 0.4 LDF units for 30 minutes, then aggressive clinical observation should be performed (alert level 3, or "red alert") and exploration should be strongly considered. Falsely elevated measurements can be caused by vibration, motion of the probe or tissue, or location of the probe over a macroscopic blood vessel. False low readings are quite rare but can result from partial probe detachment from the flap or coagulum accumulating on the probe. Once artifacts are ruled out, LDF readings have a high level of credibility and, in the authors' experience, significantly improve salvage rates.

Colour flow duplex scanning: an accurate, non-invasive technique for preoperative evaluation of the vascular supply of the rectus abdominis myocutaneous flap

Forty patients were examined with colour Doppler to study the vascularization of rectus abdominis myocutaneous flaps before operations. The accuracy of this non-invasive ultrasound technique allowed us to describe the characteristics of the blood flow, including volume and velocity, diameter of vessels and their transverse section area within the epigastric arteries which supply the superior and inferior vascular pedicles of the flap. Vessels are drawn on the skin surface so that the flap can be more precisely and rapidly dissected. We are now using colour Doppler to assess variations in the diameter of vessels and in other variables of blood flow within the vascular pedicle of the transferred flap. These evaluations before and after operation are a great help to the reconstructive surgeon in the choice of operation and will lead to an appreciable reduction in postoperative morbidity.