Implantable Doppler Ultrasound Monitoring in Head and Neck Free Flaps: Balancing the Pros and Cons

Second free jejunum transfer after flap loss does not affect oral intake: A retrospective case-control study

PURPOSE

Free jejunum transfer is one of the standard procedures for restoring oral intake after total pharyngo-laryngo-esophagectomy. Flap loss leading to a second free jejunum transfer rarely occurs. This study investigated the impact of a second free jejunum transfer on post-operative oral intake.

METHODS

A retrospective review was conducted on patients who underwent a first free jejunum transfer between July 1998 and December 2019. A total of 367 patients were included in the study. Among them, 17 patients who underwent a second free jejunum transfer because necrosis constituted the second free jejunum transfer group, whereas 350 patients who did not require a second free jejunum transfer formed the first free jejunum transfer group. The incidence of dysphagia requiring tube feeding and post-operative complications was compared between the two groups. Moreover, risk factors for dysphagia and complications were estimated.

RESULTS

There were no statistically significant differences in the incidence of dysphagia post-operation between the two groups. A second free jejunum transfer was a statistically significant factor for complications at 2- and 6-months post-operation; however, there were no significant differences in complication rates at the 12-month follow-up. Furthermore, there were no significant differences in the incidence of severe complications between the two groups.

CONCLUSION

Although a second free jejunum transfer increases early complications, it is not associated with major complications and does not negatively impact oral intake. These findings support the conclusion that free jejunum transfer is safe and helps maintain post-operative quality of life.

Implantable arterial doppler efficacy in free flap reconstruction: A systematic review and meta-analysis

The implantable arterial doppler (IAD) is frequently used to postoperatively monitor free flaps with high accuracy, but there are no guidelines for its use. Bedside exam is used adjunctively to determine necessary intervention. This systematic review seeks to discover why the doppler is used adjunctively despite its established record of accuracy. Criteria for inclusion and exclusion were established. In total, 280 articles were found on PubMed and Web of Science, then screened accordingly. Data from 22 articles were analyzed using a bivariate hierarchical random effects model. Twenty-two studies yielded 2996 total patients undergoing 3127 free flap procedures. The meta-analysis found a high sensitivity of 0.809 (95% CI = 0.709, 0.880) and specificity of 0.966 (95% CI = 0.947, 0.979). False-positive rate was found to be 0.034 (95% CI = 0.021, 0.053). Positive and negative predictive values were 0.711 (95% CI = 0.581, 0.817) and 0.979 (95% CI = 0.966, 0.988). Positive and negative likelihood ratios were 24.7 (95% CI = 14.5, 39.5) and 0.20 (95% CI = 0.12, 0.30). The established efficacy of the IAD is supported by this study. Clinical exams may remain as the final adjunct due to the risks of inaccurate IAD signals. Further studies are warranted to optimize its use for future practice guidelines.

Attached compared with unattached surface probes for monitoring flap perfusion in microvascular head and neck reconstruction: a feasibility study

Unattached surface probes are commonly used with the O2C analysis system (LEA Medizintechnik, Germany) to monitor microvascular free flap perfusion. This study compared attached and unattached surface probes for extraoral free flaps. The study included 34 patients who underwent extraoral microvascular head and neck reconstruction between 2020 and 2022. Flap perfusion was monitored postoperatively using the O2C analysis system at 0, 12, 24, 36, and 48 h, with an attached surface probe at 3 mm tissue depth and an unattached surface probe at 2 mm and 8 mm tissue depths. Clinical complications, technical errors, and perfusion measurement values were compared. No clinical complications (attachment suture infections) or technical errors (probe detachment) occurred. Flap blood flow values of the probes were partially different (3 mm vs. 2 and 8 mm: p < 0.001; p = 0.308) and moderately correlated (3 mm with 2 and 8 mm: r = 0.670, p < 0.001; r = 0.638, p < 0.001). Hemoglobin concentration and oxygen saturation values were generally different (3 mm vs. 2 and 8 mm: all p < 0.001) and variably correlated (3 mm with 2 and 8 mm: r = 0.756, r = 0.645; r = 0.633, r = 0.307; all p < 0.001). Both probes are comparable in terms of technical feasibility and patient safety, with flap perfusion values dependent on tissue measurement depth.

Flap perfusion monitoring with an attached surface probe in microvascular reconstruction of the oral cavity

OBJECTIVES

Postoperative flap monitoring is essential in oral microvascular reconstruction for timely detection of vascular compromise. This study investigated the use of attached surface probes for the oxygen-2-see (O2C) analysis system (LEA Medizintechnik, Germany) for intraoral flap perfusion monitoring.

MATERIALS AND METHODS

The study included 30 patients who underwent oral reconstruction with a microvascular radial-free forearm flap (RFFF) or anterolateral thigh flap (ALTF) between 2020 and 2022. Flap perfusion was measured with attached (3-mm measurement depth) and unattached surface probes (2- and 8-mm measurement depths) for the O2C analysis system at 0, 12, 24, 36, and 48 h postoperatively. Flap perfusion monitoring with attached surface probes was evaluated for cut-off values for flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation indicative of vascular compromise and for accuracy and concordance with unattached surface probes.

RESULTS

Three RFFFs were successfully revised, and one ALTF was unsuccessfully revised. The cut-off values indicative of vascular compromise for flap perfusion monitoring with attached surface probes were for RFFF and ALTF: blood flow < 60 arbitrary units (AU) and < 40AU, hemoglobin concentration > 100AU and > 80AU (both > 10% increase), and hemoglobin oxygen saturation < 40% and < 30%. Flap perfusion monitoring with attached surface probes yielded a 97.1% accuracy and a Cohen's kappa of 0.653 (p < 0.001).

CONCLUSIONS

Flap perfusion monitoring with attached surface probes for the O2C analysis system detected vascular compromise accurately and concordantly with unattached surface probes.

CLINICAL RELEVANCE

Attached surface probes for the O2C analysis system are a feasible option for intraoral flap perfusion monitoring.

Practice Trends and Evidence-Based Practice in Microvascular Reconstruction

Microvascular and free flap reconstruction are important to the otolaryngology-head and neck surgery practice. Herein, the reader will find an up-to-date discussion of various evidence-based practice trends related to microvascular surgery, including surgical techniques, anesthetic and airway considerations, free flap monitoring and troubleshooting, surgical efficiency, and both patient-related and surgeon-related risk factors that may affect outcomes.

The Use of the Implantable Doppler Probe as a Blood Flow Monitoring Device in Clinical Settings: A Narrative Review of the Evidence

OBJECTIVES

In the past decade, the implantable Doppler probe has been studied widely as a blood flow-monitoring device in reconstructive and transplant surgical specialities. Its utility as an effective postoperative monitoring technique is still debatable, with no clear guidelines in clinical practice. Here, we mapped the current evidence on the usefulness of the implantable Doppler probe as a blood flow-monitoring device. The objective was to present an up-to-date assessment of the benefits and limitations of using implantable Doppler probes in clinical and experimental clinical settings.

MATERIALS AND METHODS

We conducted a literature search using the Cochrane Library and Healthcare Databases Advanced Search and using implantable Doppler probe, transplant, graft, and flap as key words. The search yielded 184 studies, with 73 studies included after exclusions. We evaluated, synthesized, and summarized the evidence from the studies in tabular form.

RESULTS

There is clinical equipoise regarding the effectiveness of implantable Doppler probe as a flow sensing technique. The main reason is the lack of information and gaps in the evidence regarding the benefits and limitations of using implantable Doppler probes in clinical practice.

CONCLUSIONS

The implantable Doppler probe has the potentialto be used as an adjunctpostoperativeblood flow-monitoring device. However, keeping in view of technical limitations, its signals should be interpreted alongside traditional clinical assessment techniques to determine the patency of microvascular anastomosis. Although evidence in this review will inform clinical practice in transplant and reconstructive surgical specialties, a prospective randomized controlled study with a larger patient cohort is required to evaluate the effectiveness of this probe in clinical settings.

Continuous intraoperative perfusion monitoring of free microvascular anastomosed fasciocutaneous flaps using remote photoplethysmography

Flap loss through limited perfusion remains a major complication in reconstructive surgery. Continuous monitoring of perfusion will facilitate early detection of insufficient perfusion. Remote or imaging photoplethysmography (rPPG/iPPG) as a non-contact, non-ionizing, and non-invasive monitoring technique provides objective and reproducible information on physiological parameters. The aim of this study is to establish rPPG for intra- and postoperative monitoring of flap perfusion in patients undergoing reconstruction with free fasciocutaneous flaps (FFCF). We developed a monitoring algorithm for flap perfusion, which was evaluated in 15 patients. For 14 patients, ischemia of the FFCF in the forearm and successful reperfusion of the implanted FFCF was quantified based on the local signal. One FFCF showed no perfusion after reperfusion and devitalized in the course. Intraoperative monitoring of perfusion with rPPG provides objective and reproducible results. Therefore, rPPG is a promising technology for standard flap perfusion monitoring on low costs without the need for additional monitoring devices.

Comparison of Hyperspectral Imaging and Microvascular Doppler for Perfusion Monitoring of Free Flaps in an In Vivo Rodent Model

To reduce microvascular free flap failure (MFF), monitoring is crucial for the early detection of malperfusion and allows timely salvage. Therefore, the aim of this study was to evaluate hyperspectral imaging (HSI) in comparison to micro-Doppler sonography (MDS) to monitor MFF perfusion in an in vivo rodent model. Bilateral groin flaps were raised on 20 Sprague−Dawley rats. The femoral artery was transected on the trial side and re-anastomosed. Flaps and anastomoses were assessed before, during, and after the period of ischemia every ten minutes for overall 60 min using HSI and MDS. The contralateral sides’ flaps served as controls. Tissue-oxygenation saturation (StO2), near-infrared perfusion index (NPI), hemoglobin (THI), and water distribution (TWI) were assessed by HSI, while blood flow was assessed by MDS. HSI correlates with the MDS signal in the case of sufficient and completely interrupted perfusion. HSI was able to validly and reproducibly detect tissue perfusion status using StO2 and NPI. After 40 min, flap perfusion decreased due to the general aggravation of hemodynamic circulatory situation, which resulted in a significant drop of StO2 (p < 0.005) and NPI (p < 0.005), whereas the Doppler signal remained unchanged. In accordance, HSI might be suitable to detect MFF general complications in an early stage and further decrease MFF failure rates, whereas MDS may only be used for direct complications at the anastomose site.

The Role of Split Anterolateral Thigh Free Flaps in Reconstructive Surgery: a Systematic Review and Case Report

Radical tumor ablation or severe trauma can result in challenging tissue defects. The split anterolateral thigh free flap has been promoted as an ideal option for complex defects. We aimed to evaluate whether this flap could be performed without major morbidity. A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines was conducted to assess this hypothesis. An illustrative case about pharyngeal reconstruction is discussed, and the role of free split anterolateral thigh free flaps in modern reconstructive surgery is evaluated. The systematic search of literature yielded 221 studies with 7 articles about free anterolateral thigh flaps fully split in two separate flaps based on one pedicle. Favorable outcomes in a total of 31 patients were described. Tissue defects were mainly located at extremities, chest wall, lip, and cheek. A low complication incidence was reported in all studies, in terms of flap loss, donor site morbidity, and general wound healing problems. The flap was utilized for pharyngeal reconstruction and simultaneous neck resurfacing, which allowed a more convenient way of flap monitoring in the present case. Being technically a rather demanding flap variant, splitting the anterolateral thigh free flap has still become an accepted technique among microsurgeons. Currently, literature suggests that it can be performed without major complications for reconstructing extremities and the head and neck area. Rearrangement of the flap units in pharyngeal reconstruction increases the flap’s versatility as it allows neck resurfacing and external monitoring of buried inaccessible flaps.

Implantable Doppler Removal After Free Flap Monitoring Among Head and Neck Microvascular Surgeons

OBJECTIVE

Investigate current practice patterns of head and neck microvascular reconstructive surgeons when removing an implantable Doppler after free flap surgery.

STUDY DESIGN

Cross-sectional survey study.

METHODS

Survey distributed to head and neck microvascular reconstructive surgeons. Data regarding years performing free tissue transfer, case numbers, management of implantable Doppler wire, and complications were collected.

RESULTS

Eighty-five responses were analyzed (38,000 cases). Sixty-six responders (77.6%) use an implantable Doppler for postoperative monitoring, with 97% using the Cook-Swartz Doppler Flow Monitoring System. Among this group, 65.2% pull the wire after monitoring was complete, 3% cut the wire, and 31.8% have both cut and pulled the wire. Of those who have cut and pulled the wire, 48% report cutting and pulling the wire with equal frequency, 43% formerly pulled the wire and now cut the wire, and 9% previously cut the wire but now pull the wire. Of those who pull the wire, there were two injuries to the pedicle requiring return to the operating for flap salvage, and one acute venous congestion. Of the nine who previously pulled the wire, six (67%) cited concerns with major bleeding/flap compromise as the reason for cutting the wire.

CONCLUSION

In this study, most surgeons use an implantable Doppler for monitoring of free flaps postoperatively. In extremely rare instances, pulling the implantable Doppler wire has resulted in flap compromise necessitating revision of the vascular anastomosis. Cutting the wire and leaving the proximal portion in the surgical site has been adopted as a management option.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.