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Page 8 of 26 Chen et al. Plast Aesthet Res 2023;10:24 https://dx.doi.org/10.20517/2347-9264.2022.136

Microdialysis [164-168] A double-lumen microdialysis catheter is Sensitivity: 100% Sensitive to flow compromise Invasive, unable to perform Not yet recommended in routine
introduced into the flap and perfusion Specificity: 92.5-100% before clinically apparent, able continuous monitoring, sample postoperative breast monitoring, given
fluid is collected. Fluid is subsequently PPV: 66.7-100% to monitor buried flaps analysis is not immediate, high false the presence of other continuous and
analyzed for products of anaerobic NPV: 100% positive rate resulting in unnecessary non-invasive modalities. Can consider
respiration, including low glucose and Accuracy: 93.5-100% re-explorations and higher treatment use in buried flaps when other forms of
elevated lactate concentrations SR: 83-100% costs, unable to distinguish between monitoring are not feasible
venous and arterial flow, and costly
Fluorescent ICG ICG is injected intravenously and Sensitivity: 100% Non-invasive, provides real- Unable to perform continuous Recommended for intraoperative
[180,181]
Angiography fluoresces near-infrared light. An Specificity: 86-100% time imaging of anastomotic monitoring, not readily available at the monitoring but not as a primary
infrared-sensitive camera captures these PPV: 100% patency, and highly sensitive bedside, less sensitive to venous monitoring tool postoperatively
emissions to provide vessel imaging NPV 100% to arterial thrombosis thrombosis, costly
Accuracy: 100%
SR: 100%
PPV: positive predictive value, NPV: negative predictive value, SR: salvage rate.

continuous monitoring when a skin paddle is not available, such as in buried skin flaps or muscle flaps without a skin paddle.

Tissue ischemia
Near-Infrared Spectroscopy (NIRS) tissue oximetry is an important tool that has been shown to detect flap compromise before it is clinically apparent,
decrease rates of flap loss, and improve rates of flap salvage compared to conventional techniques . While more expensive upfront than continuous Doppler
[81]
techniques, NIRS has demonstrated an overall potential cost benefit across multiple studies [75,82-84] . Pelletier et al. found an average reduction of $1,937 per
patient when monitored on the surgical floor with NIRS tissue oximetry compared to the surgical intensive care unit (ICU) . Additionally, given the
[82]
quantitative output of NIRS compared to Doppler technology, an automated text message alert system has been developed, allowing for rapid notification of
[85]
the surgical team . The potential for decreased time to re-exploration, a critical factor in flap salvage, makes NIRS a promising technology. While NIRS is a
valuable tool to continuously monitor flaps with a skin paddle, no single monitoring device should supersede a thorough physical examination and individual
clinical experience.

Flap monitoring protocols
Currently, there is no universally recognized protocol or standardized practice for flap monitoring following microsurgical breast reconstruction. Historically,
flaps have been monitored in an intensive care or step-down setting for 1 or more days postoperatively, given that the majority of complications occur within
the first 24-48 h after surgery [85,86] . With advancements in flap monitoring technologies, many institutions have altered their protocols to allow for early
disposition to the floor without increasing the risk of flap failure or postoperative complications [82,83,87-89] . In line with the available literature, we present our
institution's flap monitoring protocol in [Figure 2], adapted from Khansa et al. to reflect our institution’s recommendation for timing and location of
monitoring, and criteria for takeback . Nonetheless, we recognize that ultimately a surgeon’s approach to flap monitoring should take into account individual
[90]
patient factors, institutional resources, and the evolving literature.