Technology in Microvascular Surgery

Increased Time Interval of Postoperative Flap Monitoring After Autologous Breast Reconstruction

BACKGROUND

Hourly flap checks are the most common means of flap monitoring during the first 24 hours following autologous breast reconstruction (ABR). This practice often requires intensive care unit (ICU) admission, which is a key driver of health care costs and decreased patient satisfaction. This study addresses these issues by demonstrating decreased cost and length of admission associated with a 4-hour interval between flap checks during the first 24 hours following ABR.

METHODS

This is a retrospective review of ABR surgeries performed by multiple surgeons from 2017 to 2020. Two cohorts were identified, one that underwent flap checks every hour in the ICU (Q1 cohort) and the other that underwent flap checks every 4 hours on the hospital floor (Q4 cohort). Our primary outcome measures were length of stay (LOS), flap takebacks, flap loss, and encounter cost.

RESULTS

Rates of flap takeback and loss did not differ between cohorts (P = 0.18, P = 0.21). The Q4 cohort's average LOS was shorter than the Q1 cohort (P = 0.002). The Q4 cohort's average cost was also $25,554.80 less than the Q1 cohort (P < 0.001). This association persisted after controlling for LOS, operating room takeback, timing and laterality of reconstruction, and flap configuration (hazard ratio = 0.65, P = 0.0007).

CONCLUSION

This study demonstrates the benefits of lengthened flap check intervals during the first 24 hours following ABR. These intervals decrease the cost of ABR while also maintaining safety, making ABR a more accessible option for breast reconstruction patients.

DIEP flap perfusion assessment using microdialysis versus Doppler ultrasonography: A comparative study

BACKGROUND

The increasing number of buried free-tissue transfer procedures and the need for an objective method to evaluate vascular complications of free flaps has led to the development of new technologies. Microdialysis has been used to monitor free flaps using interstitial biological markers. Previous uses mainly focused on muscular flaps. Our aim is to compare external Doppler ultrasonography (EDU) evaluation versus microdialysis in the early follow-up of adipocutaneous flaps, and propose an efficient postoperative monitoring protocol.

METHODS

We retrospectively assessed 68 consecutive DIEP flaps (50 patients) performed between January 2019 and March 2021. All flaps received standardized post-operative monitoring using clinical signs, EDU and microdialysis. Glucose and lactate concentrations were assessed using glucose <1 mmol/L and lactate >6 mmol/L as ischemic trend thresholds. We calculated Glucose/Lactate ratio as a new parameter for the assessment of flap viability.

RESULTS

Among all the 68 flaps, two flaps returned to the operative theater when a combination of unsatisfactory microdialysis values and clinical/EDU signs identified vascular impairment; only one developed total flap necrosis. Reoperation rate was 2.94% with an overall flap success rate of 98.53%. External Doppler ultrasonography had 100% sensitivity and 82% specificity, while microdialysis had 100% sensitivity and 100% specificity.

CONCLUSIONS

Microdialysis values proved flap viability sooner than external Doppler ultrasonography, making it an excellent tool for post-operative monitoring. With the appropriate thresholds for glucose and lactate concentrations, and glucose/lactate ratio used as a new parameter, it can help potentially avoiding unnecessary re-explorations, and reducing flap ischemia times.

A new protocol for improving immediate monitoring of skin-island free flap with near-infrared spectroscopy and ultrasound

BACKGROUND

Postoperative monitoring is essential for detecting early complications and improving the salvage rate of free flaps. We propose a new protocol for free flap monitoring based on the combination of near-infrared spectroscopy (NIRS) and ultrasound.

METHODS

All free flaps with a skin paddle were included and divided into two groups according to the immediate postoperative monitoring method used: ultrasound examination (control group) or those monitored using our protocol (study group). The number of surgical revisions, intraoperative findings, immediate flap failure, sensitivity, and specificity were compared between the two groups.

RESULTS

A total of 221 free flaps performed in 209 patients were included. The NIRS automatically detected vascular compromise in 21.8% of cases. A complication was confirmed in half of these cases by ultrasound examination, and surgical reintervention was indicated (10.9%), even in the absence of clinical changes in the skin paddle. In all the surgical revisions, the complication was confirmed, and there was no flap necrosis in the non-revised cases. The salvage rate for revised flaps and the flap survival rate were higher in the study group (salvage rate: 25% vs 72.7%; survival rate: 92.5% vs 97%). A sensitivity of 100% and a specificity of 100% were found for the combination of both monitoring methods.

CONCLUSION

The proposed protocol is a non-invasive and reliable method for early identification of postoperative complications of free flaps that allows higher rates of salvage rate and reduces the need for specific staff with continuous on-site presence for flap monitoring.

The Efficacy of Hydrodilatation for the Prevention of Vasospasm following Microsurgical Anastomosis

INTRODUCTION

 Vasospasm is a major problem following microsurgical reconstruction which can result in the partial or complete loss of the flap tissue. The aim of this study was to investigate the efficiency of hydrodilatation for the prevention of vasospasm.

MATERIAL AND METHODS

 Thirty male Wistar rats were used for this experimental study. Femoral arteries of were exposed, photographed, and transected. In group 1, group 2, and group 3 papaverine solution, hydrodilatation, and minimal mechanical dilatation (control group) was performed, respectively. The anastomosis was completed and the arteries were photographed again 10 minutes after completion of the anastomosis. Following 7-day period samples for transmission electron microscopy (TEM) and light microscopy were obtained.

RESULTS

 The mean vessel diameters prior to transection were 0.43, 0.45, and 0.52 mm in the papaverine, hydrodilatation, and control groups, respectively. The mean vessel diameter 10 minutes following the completion of anastomosis was 0.76, 0.75, and 0.51 mm in the papaverine, hydrodilatation, and control groups, respectively. Median score for papaverine group regarding histological parameters of regular endothelial lining and lumen, neutrophil infiltration, vascular congestion, and edema in tunica adventitia was 2, 3, 2, and 3 positive, respectively. Median score for the papaverine group regarding histological parameters of regular endothelial lining and lumen, neutrophil infiltration, vascular congestion, and edema in tunica adventitia was 3, 3, 3, and 3 positive, respectively. All the histological scores were negative in the control group. The difference between the control group and the experiment groups 1 and 2 was significant regarding all four histological parameters (p < 0.05).

CONCLUSION

 Hydrodilatation and papaverine application were both effective in preventing vasospasm following microsurgical intervention but papaverine caused slightly less damage to the endothelial lining and less edema in the tunica adventitia when compared with the hydrodilatation. Hydrodilatation group showed a vasodilatory effect that was statistically similar to that of papaverine, which has a proven efficacy.

Intraoperative near-infrared spectroscopy for pedicled perforator flaps: a possible tool for the early detection of vascular issues

Background

Pedicled perforator flaps can present postoperative complications similar to those encountered in free flap surgery. Beyond a clinical evaluation, there is still no reliable technical aid for the early prediction of vascular issues. The aim of this study was to assess the support of near-infrared spectroscopy technology as an intraoperative tool to anticipate postsurgical flap ischemia.

Methods

We prospectively enrolled 13 consecutive patients who were referred to our hospital from March 2017 to July 2018 and required a reconstructive procedure with a pedicled fasciocutaneous perforator flap. We measured flap peripheral capillary oxygen saturation (SpO₂) in each patient with a Somanetics INVOS 5100C Cerebral/Somatic Oximeter (Medtronic), both before and after transposition. Patient demographics, operative data, and complications were then recorded during the following 6 months. We analyzed the data using the Wilcoxon signed-rank test and linear regression.

Results

The mean flap SpO₂ before and after transposition was 92%±3% and 78%±19%, respectively. The mean change in SpO₂ was 14%±17%, with a range of 0% to 55%. The change in saturation and mean saturation ratio were significantly different between patients with and without postoperative flap necrosis.

Conclusions

An immediate quantitative analysis of flap peripheral capillary SpO₂ after transposition has never before been described. In our experience, an intraoperative drop in SpO₂ equal to or greater than 15%–20% predicted vascular complications in pedicled perforator flaps. Conversely, flap size and rotation angle were not correlated with the risk of flap necrosis.

Duplex echography as an adjuvant tool to clinical examination to detect early postoperative free flap vascular compromise

BACKGROUND

Clinical examination remains the cornerstone for postoperative monitoring of free flaps but is highly dependent on the surgeon's ability and experience. Duplex echography provides a noninvasive objective evaluation of tissue perfusion. The authors hypothesized that duplex echography may be a more sensitive and specific monitoring method for early detection of postoperative flap compromise compared to clinical examination alone. The goal was to evaluate any differences between combined duplex echography and clinical examination flap monitoring versus isolated clinical evaluation.

METHODS

A total of 730 free flaps in 700 patients were included in the study. We conducted an intra-subject prospective study of a cohort of patients who underwent free flap reconstruction in our unit to compare clinical examination with duplex echography for postoperative monitoring. An inter-subject study was also undertaken comparing the prospective cohort with a historical control group of patients in whom free flap monitoring was made using clinical examination alone. The patency flow and velocities through the artery and vein of the flap were measured at the donor and recipient vessels of every anastomosis by duplex scanning, by the same plastic surgeon every 4 hr, during the first 18 hr after surgery.

RESULTS

Duplex echography and clinical evaluation were used in 175 patients. The historical cohort included a total of 525 flaps. Every patient with suspicion of vascular compromise based on duplex echography was taken back for surgical re-exploration. There were no cases of overdiagnosis using duplex echography (Sensitivity 100%, Specificity 100%). Clinical evaluation detected issues with the vascularan astomoses in 23/175 flaps. However, it failed to detect 12/22 cases which presented with vascular complications and gave a false indication of possible complications in 13 flaps (Sensitivity 45%, Specificity 92%).

CONCLUSION

In our practice, duplex echography is considered a useful adjunct monitoring tool for early detection of postoperative flap compromise, which compliments clinical evaluation. It provides anatomic and hemodynamic information of the vascular status and may therefore increase survival of flaps by allowing earlier detection of vascular compromise, compared to clinical examination alone, in postoperative monitoring of free flaps.

Review and update on the use of the microanastomotic coupler device for arterial anastomosis in free tissue transfer

While a simple interrupted sutured anastomosis remains the gold standard in microsurgery, the introduction of the microanastomotic coupler device (MACD) has decreased procedure time and thrombosis risk, and improved the patency of venous anastomoses. The aim of this review is to update the evidence-based advantages of the MACD on arteries, based on clinical and experimental data, and to compare them to the hand-sewn approach in free flap transfer. All relevant articles that appeared in the PubMed and Medline/Ovid databases during the past three decades were reviewed. After exclusions, 11 studies were retained and discussed. The MACD had a generally shorter arterial anastomosis time, with improved flap survival and reduced ischaemia compared with the hand-sewn approach. The use of the MACD in arterial anastomosis is an efficient and less time-consuming alternative to the hand-sewn technique, provided that the selection of vessels is appropriate and the vessel diameter is large enough to do the anastomosis.

Influence of preoperative imaging on fibula free flap harvesting

INTRODUCTION

The fibula free flap (FFF) is the gold standard for the reconstruction of large maxillofacial defects. Magnetic resonance angiography (MRA) seems to supersede digital subtraction angiography (DSA) as the reference in preoperative evaluation, being non-invasive and having equivalent diagnostic results. The aim of this study was to assess the impact of preoperative MRA versus DSA on the viability of FFF and its success rate.

MATERIAL AND METHODS

A total of 216 patients, who underwent mandibular or maxillary FFF reconstruction from January 1995 to January 2011, were retrospectively included in the study. Of them, 101 patients underwent preoperative DSA and 115 underwent MRA. Recorded criteria were as follows: age, sex, tobacco consumption, defect etiology, preoperative vascular assessment, donor-site choice and flap failure. The DSA group was compared to the MRA group.

RESULTS

The harvested side was switched in 15.7% of cases with preoperative MRA versus 4% with DSA. Our success rate was higher (96.1%) with MRA than with DSA (88.1%) (P<0.05). More atherosclerotic patients (P=0.004) were diagnosed through MRA. MRA and DSA showed similar results in anatomical variation detection.

CONCLUSION

MRA is less invasive and more effective in atherosclerosis detection than DSA. Therefore, donor-site switching was more frequent in the MRA group, which led to a better success rate. MRA should replace DSA as the reference in preoperative assessment.

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.

Postoperative monitoring of free flap reconstruction: A comparison of external Doppler ultrasonography and the implantable Doppler probe

HYPOTHESIS

The time to detection of vascular compromise and the postoperative time to re-exploration are shorter using the implantable Doppler (ID) probe, thereby resulting in earlier surgical re-exploration and a higher flap salvage rate.

METHODS

A single-centre experience with 176 consecutive free flap reconstructions in 167 patients from 2000 to 2008 in a university-based teaching hospital by retrospective chart review is presented.

RESULTS

There was a significant difference in overall flap survival (ID 98.0%, external Doppler [ED] 89.3%) and total flap loss (ID 2.0%, ED 10.7%) between the two groups (P=0.03). The difference in flap salvage rate was not significant (ID 90.9%, ED 63.6%; P=0.068). The false-positive (ID 0%, ED 3%; P=0.18) and false-negative rates (ID 0.0%, ED 4.5%; P=1.0) were not significantly different. There was also a lower median postoperative time to re-exploration for the ID group, from 48 h to one week after initial surgery (ID 74.5 h, ED 136.8 h; P=0.05).

CONCLUSION

The present analysis revealed a potential benefit for the ID probe in the postoperative monitoring of free tissue transfers.

Postoperative monitoring of free flap reconstruction: A comparison of external Doppler ultrasonography and the implantable Doppler probe

Hypothesis

The time to detection of vascular compromise and the postoperative time to reexploration are shorter using the implantable Doppler (ID) probe, thereby resulting in earlier surgical reexploration and a higher flap salvage rate.

Methods

A single-centre experience with 176 consecutive free flap reconstructions in 167 patients from 2000 to 2008 in a university-based teaching hospital by retrospective chart review is presented.

Results

There was a significant difference in overall flap survival (ID 98.0%, external Doppler [ED] 89.3%) and total flap loss (ID 2.0%, ED 10.7%) between the two groups (P=0.03). The difference in flap salvage rate was not significant (ID 90.9%, ED 63.6%; P=0.068). The false-positive (ID 0%, ED 3%; P=0.18) and false-negative rates (ID 0.0%, ED 4.5%; P=1.0) were not significantly different. There was also a lower median postoperative time to reexploration for the ID group, from 48 h to one week after initial surgery (ID 74.5 h, ED 136.8 h; P=0.05).

Conclusion

The present analysis revealed a potential benefit for the ID probe in the postoperative monitoring of free tissue transfers.

Metamizole: an effective solution for vasospasm

OBJECTIVE

Vasospasm is a major problem during microsurgery, and a variety of pharmacological agents are used to alleviate vasospasm. This study aimed to demonstrate the effect of metamizole on vasospasm and to compare it with lidocaine and papaverine, both of which are commonly used to correct vasospasm.

METHODS

Thirty-five female rats were randomly divided into four groups: Group 1, 2, 3, and 4, which were the control (n = 8), metamizole (n = 9), papaverine (n = 9), and lidocaine (n = 9) treatment groups, respectively. Both femoral arteries of all of the rats were dissected, and they were immediately photographed. The pharmacological agents or saline in the control group were topically applied to the arteries, accordingly. The arteries were photographed again at time points 5, 10, 20 and 30 minutes after application of the agents. The images were transferred to a computer and the arteries' diameters were measured in mm.

RESULTS

All of the pharmacological treatments increased the diameter of the arteries significantly during the observation period. However, comparison between the groups indicated that metamizole and papaverine produced significantly more vasodilation than the lidocaine group, for all time points measured after application.

CONCLUSION

These findings show that topically applied metamizole is as effective as papaverine at alleviating vasospasm during the 30 minutes time interval. This administration may be considered as a good alternative to correct vasospasm during microsurgery.

Soft tissue engineering in craniomaxillofacial surgery

Craniofacial soft tissue reconstruction may be required following trauma, tumor resection, and to repair congenital deformities. Recent advances in the field of tissue engineering have significantly widened the reconstructive armamentarium of the surgeon. The successful identification and combination of tissue engineering, scaffold, progenitor cells, and physiologic signaling molecules has enabled the surgeon to design, recreate the missing tissue in its near natural form. This has resolved the issues like graft rejection, wound dehiscence, or poor vascularity. Successfully reconstructed tissue through soft tissue engineering protocols would help surgeon to restore the form and function of the lost tissue in its originality. This manuscript intends to provide a glimpse of the basic principle of tissue engineering, contemporary, and future direction of this field as applied to craniofacial surgery.

Influence of vascular twisting on the supermicroanastomosis of superficial inferior epigastric artery

Arterial microanastomoses with small-caliber vessels, such as those with an internal diameter less than 0.2 mm, are susceptible to inadvertent twisting. A total of 20 supermicroanastomoses were performed in the superficial inferior epigastric artery (SIEA)-based flap model of ten 10-week old, 300- to 350-g male Sprague-Dawley rats. Two rats with 4 flaps comprised each experimental group: a negative control, a control with end-to-end SIEA arterial supermicroanastomosis, and 3 experimental groups (EAs), such as EA1, 2, and 3 with 90-, 180-, and 270-degree twisting supermicroanastomosis, respectively. Each SIEA was clamped with a Superfine Vascular Clamp (S&T Co, Neuhausen, Switzerland) and anastomosed with 6 stitches. On postoperative day 10, the skin flap surface texture had no color change, and skin necrosis was not found in any group within a 1.0-mm grid measurement in less than 1% of the whole skin flap surfaces. There were statistically significant differences between the groups in 4 criteria, such as cellular swelling, nuclear pleomorphism, nuclear swelling, and microvessel numbers. The pulsatility index was increased in the EA1 and EA2 on postoperative days 1 and 2, showing decrease in the similar preoperative value on postoperative day 10, but decreased pulsatility index was continuous in the EA3 during the postoperative day 10. The resistance index was significantly different between preoperative and postoperative day 10 especially in the EA2 and EA3. Ultramicroscopic findings in the EA3 group showed an increase in tunica media necrosis, convolution of the internal elastic lamina, and densely packed platelets, fibrins, and erythrocytes.