Monitoring Breast Reconstruction Flaps Using Near-Infrared Spectroscopy Tissue Oximetry

An overview of current assessment techniques for evaluating cutaneous perfusion in reconstructive surgery

This article provides a comprehensive analysis of modern techniques used in the assessment of cutaneous flaps in reconstructive surgery. It emphasizes the importance of preoperative planning and intra- and perioperative assessment of flap perfusion to ensure successful outcomes. Despite technological advancements, direct clinical assessment remains the gold standard. We categorized assessment techniques into non-invasive and invasive modalities, discussing their strengths and weaknesses. Non-invasive methods, such as acoustic Doppler sonography, near-infrared spectroscopy, hyperspectral imaging thermal imaging, and remote-photoplethysmography, offer accessibility and safety but may sacrifice specificity. Invasive techniques, including contrast-enhanced ultrasound, computed tomography angiography, near-infrared fluorescence angiography with indocyanine green, and implantable Doppler probe, provide high accuracy but introduce additional risks. We emphasize the need for a tailored decision-making process based on specific clinical scenarios, patient characteristics, procedural requirements, and surgeon expertise. It also discusses potential future advancements in flap assessment, including the integration of artificial intelligence and emerging technologies.

Second sensor to improve near-infrared spectroscopy flap monitor utility: A prospective study

OBJECTIVE

This study assesses whether use of continuous noninvasive near-infrared spectroscopy (NIRS) sensor on head and neck free flap (FF) with a second sensor on nonoperated tissue improves distinction between systemic hypoperfusion and FF compromise.

METHODS

Single-institution, prospective study of patients undergoing head and neck FF reconstruction from December 2018 to April 2020. FFs were continuously monitored using NIRS on a monitor paddle with a second (control) sensor on the shoulder. Crude StO2 and percent change in StO2 were compared between the FF and control sensors on each patient, and percent change and percent difference between the control and the monitor paddle were documented to assess for congruity. Sentinel events (e.g., hypotension and hematoma) were documented to assess the association with change in StO2. These events and timing of StO2 changes were noted to assess associations with change in StO2.

RESULTS

A total of 48 patients had complete data. Donor sites included 35 soft-tissue FFs and 13 fibula FFs. Average StO2 was 73.7 ± 5.5 for FFs and 71.4 ± 5.0 for control sensors. There were seven sentinel events during the study. At the time of the events, StO2 dropped significantly more for the FF than the control sensor (FF = 52.2% drop; control = 6.2% drop; p = .016). NIRS signal denoted change prior to changes in implantable arterial Doppler in all cases.

CONCLUSIONS

The addition of a second sensor when using NIRS as a primary modality for FF monitoring may improve distinction between FF compromise events and systemic hypoperfusion. By increasing accuracy of the monitor, there is a potential for decreased resident burden and decreased use of higher level of care nursing, which could reduce overall costs.

Survey of Surgeon-reported Postoperative Protocols for Deep Inferior Epigastric Perforator Flap in Breast Reconstruction

Background

The use of deep inferior epigastric perforator (DIEP) flaps is a well-established breast reconstruction technique.

Methods

A 29-question survey was e-mailed to 3186 active American Society of Plastic Surgeons members, aiming to describe postoperative monitoring practice patterns among surgeons performing DIEP flaps.

Results

From 255 responses (8%), 79% performing DIEP surgery were analyzed. Among them, 34.8% practiced for more than 20 years, 34.3% for 10-20 years, and 30.9% for less than 10 years. Initial 24-hour post-DIEP monitoring: intensive care unit (39%) and floor (36%). Flap monitoring: external Doppler (71%), tissue oximetry (41%), and implantable Doppler (32%). Postoperative analgesia: acetaminophen (74%), non-steroidal anti-inflammatory drugs (69%), neuromodulators (52%), and opioids (4.4%) were administered on a scheduled basis. On postoperative day 1, 61% halt intravenous fluids, 67% allow ambulation, 70% remove Foley catheter, and 71% start diet. Most surgeons discharged patients from the hospital on postoperative day 3+. Regardless of experience, patients were commonly discharged on day 3. Half of the surgeons are in academic/nonacademic settings and discharge on/after day 3.

Conclusions

This study reveals significant heterogeneity among the practice patterns of DIEP surgeons. In light of these findings, it is recommended that a task force be convened to establish standardized monitoring protocols for DIEP flaps. Such protocols have the potential to reduce both the length of hospital stays and overall care costs all while ensuring optimal pain management and vigilant flap monitoring.

An Updated Systematic Review and Meta-Analysis of Tissue Oximetry Versus Conventional Methods for Postoperative Monitoring of Autologous Breast Reconstruction

BACKGROUND

Tissue oximetry monitoring has shown superior outcomes to conventional monitoring methods for autologous breast reconstruction in retrospective studies with consecutive cohorts. A recent study used consecutive cohorts with tissue oximetry as the earlier cohort and found that tissue oximetry was nonsuperior. We hypothesize that improvement in microsurgical outcomes with institutional experience confounds the superiority of tissue oximetry demonstrated in prior studies. This study aimed to perform a systematic review and meta-analysis of the outcomes of tissue oximetry monitoring compared with conventional monitoring.

METHODS

Relevant studies were found using PubMed, Embase, and Web of Science searches for keywords such as near-infrared spectroscopy or tissue oximetry and microsurgery. Studies included compared tissue oximetry and conventional monitoring in autologous breast reconstruction patients. Studies were excluded if they did not contain a comparison group. Random-effective models were used to analyze early returns to the operating room, the total number of partial or complete flap loss, and late fat necrosis.

RESULTS

Six hundred sixty-nine studies were identified; 3 retrospective cohort studies met the inclusion criteria. A total of 1644 flaps were in the tissue oximetry cohort, and 1387 flaps were in the control cohort. One study contained tissue oximetry as the former cohort; 2 had tissue oximetry as the latter. Neither technique was superior for any measured outcomes. The estimated mean differences between tissue oximetry and conventional monitoring method were early returns, -0.06 (95% confidence interval [CI], -0.52 to 0.410; P = 0.82); partial flap loss, -0.04 (95% CI, -0.86 to 0.79; P = 0.93); complete flap loss, -1.29 (95% CI, -3.45 to 0.87; P = 0.24); and late fat necrosis -0.02 (95% CI, -0.42 to, 0.39; P = 0.94).

CONCLUSIONS

In a systematic review and meta-analysis of mixed timeline retrospective cohort studies, tissue oximetry does not provide superior patient outcomes and shifts our current understanding of postoperative breast reconstruction monitoring. Prospective studies and randomized trials comparing monitoring methods need to be included in the existing literature.

Comparing tissue oximetry to doppler monitoring in 1367 consecutive breast free flaps

BACKGROUND

Retrospective studies evaluating tissue oximetry in a more recent cohort have shown superiority in flap outcomes. This study compares the use of tissue oximetry in a historical cohort to clinical observation and handheld doppler in a more recent cohort. We hypothesize that there is no benefit to using tissue oximetry.

METHODS

A retrospective review was performed on patients who underwent abdominal-based autologous breast reconstruction by five microsurgeons at an academic institution from 2009 to 2020. Method of postoperative flap monitoring was determined then operative details and complications were analyzed.

RESULTS

1367 flaps were reviewed; 740 flaps in 460 patients were monitored with clinical observation and tissue oximetry, and 627 flaps in 391 patients were monitored with clinical observation and handheld doppler. There were no statistical differences in ischemic (p = .59) or congestive complications (p = .41), flap salvage rates when exploring for venous or arterial compromise (p = .52), or early flap loss (p = .56). Although not significant, acute flap-related return to the operating room was lower in the doppler group (4.6%) compared to the oximetry group (6.1%; p = .22). Flaps monitored with tissue oximetry had a statistical increase in length of stay (4.8 ± 1.4 days vs. 3.8 ± 1.6 days; p ≤ .001). The rates of late partial flap loss and fat necrosis were significantly higher in the oximetry group (2.6%, 19/740 vs. 0.3%, 2/740; p = .04) and (18.2%, 135/740 vs. 13.6%, 85/627; p = .02), respectively.

CONCLUSIONS

There is no statistical benefit to the use of tissue oximetry compared to handheld doppler in flap monitoring with regards to flap outcomes.