Flap monitoring with continuous oxygen partial tension measurement in breast reconstructive surgery: A preliminary report

Continuous oxygen monitoring to enhance ex-vivo organ machine perfusion and reconstructive surgery

Continuous oxygenation monitoring of machine-perfused organs or transposed autologous tissue is not currently implemented in clinical practice. Oxygenation is a critical parameter that could be used to verify tissue viability and guide corrective interventions, such as perfusion machine parameters or surgical revision. This work presents an innovative technology based on oxygen-sensitive, phosphorescent metalloporphyrin allowing continuous and non-invasive oxygen monitoring of ex-vivo perfused vascularized fasciocutaneous flaps. The method comprises a small, low-energy optical transcutaneous oxygen sensor applied on the flap's skin paddle as well as oxygen sensing devices placed into the tubing. An intermittent perfusion setting was designed to study the response time and accuracy of this technology over a total of 54 perfusion cycles. We further evaluated correlation between the continuous oxygen measurements and gold-standard perfusion viability metrics such as vascular resistance, with good agreement suggesting potential to monitor graft viability at high frequency, opening the possibility to employ feedback control algorithms in the future. This proof-of-concept study opens a range of research and clinical applications in reconstructive surgery and transplantation at a time when perfusion machines undergo rapid clinical adoption with potential to improve outcomes across a variety of surgical procedures and dramatically increase access to transplant medicine.

Postoperative free flap monitoring in reconstructive surgery-man or machine?

Free tissue transfer is widely used for the reconstruction of complex tissue defects. The survival of free flaps depends on the patency and integrity of the microvascular anastomosis. Accordingly, the early detection of vascular comprise and prompt intervention are indispensable to increase flap survival rates. Such monitoring strategies are commonly integrated into the perioperative algorithm, with clinical examination still being considered the gold standard for routine free flap monitoring. Despite its widespread acceptance as state of the art, the clinical examination also has its pitfalls, such as the limited applicability in buried flaps and the risk of poor interrater agreement due to inconsistent flap (failure) appearances. To compensate for these shortcomings, a plethora of alternative monitoring tools have been proposed in recent years, each of them with inherent strengths and limitations. Given the ongoing demographic change, the number of older patients requiring free flap reconstruction, e.g., after cancer resection, is rising. Yet, age-related morphologic changes may complicate the free flap evaluation in elderly patients and delay the prompt detection of clinical signs of flap compromise. In this review, we provide an overview of currently available and employed methods for free flap monitoring, with a special focus on elderly patients and how senescence may impact standard free flap monitoring strategies.

Squamous cell carcinoma of the scalp: a combination of different therapeutic strategies

A case study of a 71-year-old man with a giant cutaneous squamous cell carcinoma of the scalp and calvaria is presented, where a combination of surgical excision, reconstruction with a latissimus dorsi muscular free flap, immunotherapy, and radiotherapy were used to control the disease for two years without recurrence.

Perforator-based Adipofascial Flaps and ADM: A Novel Combined Approach to Distal Lower Extremity Defects

Due to the wide spectrum of lower extremity defect presentation, various reconstructive techniques are available. Classic adipofascial flaps are still a second choice. The authors described a new multistage reconstructive approach with perforator-based pedicled adipofascial flap.

Combined lymph node transfer and suction-assisted lipectomy in lymphedema treatment: A prospective study

BACKGROUND

Recent studies have analyzed the combination of suction-assisted lipectomy (SAL) and vascularized lymph node transfer (VLNT) in lymphedema treatment, reporting positive outcomes. However, it is difficult to draw conclusions due to the heterogeneity of the studies. Aim of this prospective study is to evaluate the effectiveness of the combination of VLNT and SAL in lymphedema treatment.

PATIENTS AND METHODS

Between January 2016 and May 2019, 94 patients with upper or lower limb stage IIb-III lymphedema were enrolled and treated with the gastroepiploic VLNT followed by SAL. Patients were prospectively evaluated through circumference measurement and clinical examination, including number of episodes of cellulitis.

RESULTS

Among patients enrolled in the study 83 were affected by lower limb lymphedema (LLL) and 11 were affected by upper limb lymphedema (ULL). Average follow-up was 3 ± 0.8 years. In the LLL group, the mean circumference reduction rates (CRR) were 60.4, 56.9, 29.6, and 55.4% above and below the knee, above the ankle, and at the foot level, respectively. A statistically significant difference was noted at all the levels (p < .05), but above the ankle (p = .059). Regarding the ULL group, the mean CRR were 80.7, 60.7, 65.0 and 49.6% above and below the elbow, at wrist and at mid-hand, respectively. CRR were reported at all the levels but no statistical difference was noted. The number of episodes of cellulitis dropped significantly (p < .05).

CONCLUSION

This study supports the use of VLNT+SAL in lymphedema grades IIb-III, with important implications for the clinical practice.

Flap Monitoring Using Transcutaneous Oxygen or Carbon Dioxide Measurements

Free tissue transfer is a cornerstone of complex reconstruction. In many cases, it represents the last option available for a patient and their reconstruction. At high-volume centers, the risk of free flap failure is low but its occurrence can be devastating. Currently, the mainstay for flap monitoring is the clinical examination. Though reliable when performed by experienced clinicians, the flap exam is largely subjective, is performed discontinuously, and often results in significant time delay between detection of flap compromise and intervention. Among emerging flap monitoring technologies, the most promising appear to be those that rely on noninvasive transcutaneous oxygen and carbon dioxide measurements, which provide information regarding flap perfusion. In this article, we review and summarize the literature on various techniques but primarily emphasizing those technologies that rely on transcutaneous gas measurements. We also define characteristics for the ideal flap monitoring tool and discuss critical barriers, predominantly cost, preventing more widespread utilization of adjunct monitoring technologies, and their implications.

Partition of Pectoralis Major Musculocutaneous Flap as a Salvage Procedure for Simultaneous Coverage of the Exposed Carotid Artery and Reconstruction of Cervical Esophagus

BACKGROUND

In advanced pharyngoesophageal cancer patients, a critical event is represented by the failure of primary reconstruction with exposure of the carotid artery and partial or total defect of the cervical esophagus. For these high-risk patients, a partitioned pectoralis major musculocutaneous (PMMC) flap can prevent carotid blowout and provide skin for simultaneous esophageal reconstruction.

METHODS

Twenty-six patients needing pharyngoesophageal reconstruction together with coverage of carotid artery exposure were included in this retrospective case series. The patients were treated with a partitioned PMMC flap, based on the branching pattern of the pectoral branch of the thoracoacromial artery and the perforators of the pectoralis major muscle, to simultaneously reconstruct the defect and provide coverage for the carotid artery.

RESULTS

In 25 patients, the partitioned PMMC flap reconstructions resulted in complete wound healing without occurrence of carotid blowout syndrome or fistula formation. Minor complications as partial flap necrosis (7.7%) and strictures formation (7.7%) were recorded but did not compromise reconstruction. Twenty-two patients were able to adopt a semisolid diet, and 4 had recurrence of cancer.

CONCLUSIONS

The partitioned PMMC flap reconstruction represents a useful salvage solution to simultaneously restore the continuity of the alimentary tract and provide reliable coverage for the exposed carotid artery.

Noninvasive Monitoring of Deep Tissue Oxygenation in Buried Flaps by Time-Resolved Near-Infrared Spectroscopy in Pigs

BACKGROUND

Flap monitoring in reconstructive surgery is particularly important because flap failure is a dramatic event for the patient and for the medical team. Noninvasive deep tissue oxygenation monitoring is a challenge. The aim of this experimental study was to assess the performance of time-resolved near-infrared spectroscopy compared with continuous-wave near-infrared spectroscopy and with invasive oxygen partial pressure measurement in pigs.

METHODS

Thirty fasciocutaneous flaps based on the superficial epigastric inferior pedicle were harvested and buried under the transcutaneous dorsal muscle (approximately 1 cm thick). An optical probe was placed on the skin above each buried flap. For each pig, two buried flaps were performed, one submitted to arterial occlusion and one to venous occlusion. Oxyhemoglobin and deoxyhemoglobin concentrations were observed for over 40 minutes before clamping, almost 20 minutes during clamping and during a period of release of approximately 20 minutes. Variations in time-resolved near-infrared spectroscopy were compared to the oxygen partial pressure and continuous-wave near-infrared spectroscopy variations.

RESULTS

All vascular events were detected by the time-resolved near-infrared spectroscopy. During arterial clamping, oxyhemoglobin decreased rapidly, whereas deoxyhemoglobin increased moderately. The divergence of oxyhemoglobin and deoxyhemoglobin curves indicated arterial occlusion. During venous clamping, deoxyhemoglobin increased, whereas oxyhemoglobin increased briefly then remained stable or decreased moderately. The initial increases in the oxyhemoglobin and deoxyhemoglobin curves indicated venous occlusion. Oxygen partial pressure failed to detect vascular events in three cases. Continuous-wave near-infrared spectroscopy could not clearly identify vascular occlusions.

CONCLUSIONS

Thus, the authors demonstrated the relevance of time-resolved near-infrared spectroscopy to buried flap monitoring. Time-resolved near-infrared spectroscopy could differentiate between arterial occlusion and venous occlusion.

Distinction between arterial and venous occlusion with tissue oxygen pressure in a porcine fascio-cutaneous flap model

BACKGROUND

In recent years, many devices have been developed to monitor free flaps. The Licox probe, which measures tissue oxygen pressure (PtO₂ ), is one of the available devices. Our aim was to demonstrate that PtO₂ could distinguish arterial from venous occlusion in a porcine fascio-cutaneous flap model.

MATERIALS AND METHODS

Twenty pigs (Sus scrofa domestica, Youna strain, males) were included in this study. The median weight was 87.6 kg (84.6-90.8). Bilateral fascio-cutaneous flaps based on the superficial inferior epigastric pedicle were harvested from each pig. Thirty-eight flaps were analyzed in this study and were monitored by a Licox system during vascular occlusion. The flaps were randomized into two groups according to the clamped vessel: the arterial group (n = 19) and the venous group (n = 19). After a stabilization period of almost 40 min, vascular clamping (arterial or venous) was performed using a microvascular clamp for almost 20 min. The curve profiles were compared between arterial and venous occlusion.

RESULTS

The inflection point was reached significantly faster in the arterial group: 11 min (9-16) for arterial clamping and 17 min (13-23) for venous clamping (p = .001). A total of 18/19 (95%) pigs in the arterial group and 13/19 (68%) in the venous group (p = .09) reached a level lower than 10 mmHg. The median duration for pressure to drop below 10 mmHg was 9 min (6-12) for arterial clamping and 10 min (9-16) for venous clamping (p = .06).

CONCLUSION

We showed that PtO₂ decreased faster in cases of arterial occlusion than in cases of venous occlusion in a pig model. Based on this observation, it may be possible to distinguish arterial from venous occlusion.