April 2020 HSC Section 4 - Plastic and Reconstructive Problems

Research Original Investigation

Indocyanine Green Angiography and Factors Associated With Perfusion of Paramedian Forehead Flaps

Figure 1. Ingress and Egress Rates of the Flap After Pedicle Clamping

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The blue triangle corresponds to the ingress rate, and the red triangle corresponds to the egress rate. Baseline equals 2 U. Ingress equals 25 U, with ingress rate of 3.3 U/s. Egress equals 6 U, with egress rate of 1.3 U/s.

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Figure 2. Ingress and Egress Rates of Cheek

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The blue triangle corresponds to the ingress rate, and the red triangle corresponds to the egress rate. Baseline equals 1 U. Ingress equals 59 U, with ingress rate of 8.9 U/s. Egress equals 47 U, with egress rate of 1.7 U/s.

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The second method assessed the ratio of the flap-to-cheek ingress (arterial inflow) and egress (venous outflow), repre- senting a relative difference in velocity of blood flow between these 2 areas independent of a particular time, as shown in Figure 1 and Figure 2 . Flap neovascularization per- fusion measures were assessed after clamping the pedicle at the beginning of the second-stage procedure. Statistical Analysis Standard descriptive statistics were calculated for the patient population and perfusion measures using SPSS, version 25.0 (IBM Corp). Univariable linear regressions were used to as- sess the association of age, sex, diabetes, tobacco use, radio- therapy exposure, pathologic diagnosis, time between stages, full vs partial thickness defect, cartilage graft use, and defect surface area with each perfusion measure. Tests of collinear- ity between these variableswere performed, in particular with time between the stages. Factors that were both statistically and clinically significant were used to construct themultivari-

During the first-stage surgical procedure, the flap was designed according to the defect size and site using aes- thetic subunit principles. 18 Real-time ICG angiography was performed to assess perfusion of the distal forehead flap after flap placement. At the second-stage surgical proce- dure, the pedicle was temporarily clamped followed by ICG angiography, which was again performed at the end of the procedure after pedicle division and flap inset. For laser- assisted ICG angiography, 2 mL of ICG (5 mg) were infused followed by a 10-mL saline bolus. With the SPY-Q software, 2 methods were used to assess neovascularization perfusion of the forehead flap. First, the ratio of distal flap perfusion compared with a reference point on the cheek was measured at 3 different times: the midpoint of ICG inflow, at maximum (peak) fluorescence of the flap, and the midpoint of ICG outflow. The mean of these measures was also calculated. The most fluorescent region on the cheek (away from a distinct blood vessel, such as branches of the facial artery) was used as the reference.

JAMA Facial Plastic Surgery May/June 2019 Volume 21, Number 3 (Reprinted)

jamafacialplasticsurgery.com

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