Rectus Abdominis Flap Replantation after 18 h Hypothermic Extracorporeal Perfusion—A Porcine Model

Abstract

Cold storage remains the clinical standard for composite tissue preservation but is time-limited. A long ischemia time during surgery will adversely affect postoperative outcomes due to ischemia-reperfusion injury. Extracorporeal perfusion (ECP) seems to be a promising alternative for prolonged preservation, but more evidence is needed to support its use and to identify optimal perfusion fluids. This article assessed musculocutaneous flap vitality after prolonged ECP and compared outcomes after replantation to short static cold storage (SCS). Unilateral musculocutaneous rectus abdominis flaps were raised from 15 pigs and preserved by 4 h SCS (n = 5), 18 h mid-thermic ECP with Histidine–Tryptophan–Ketoglutarate (HTK, n = 5) or University of Wisconsin solution (UW, n = 5). Flaps were replanted and observed for 12 h. Skeletal muscle histology was assessed (score 0–12; high scores equal more damage), blood and perfusate samples were collected and weight was recorded as a marker for oedema. Mean histological scores were 4.0 after HTK preservation, 5.6 after UW perfusion and 5.0 after SCS (p = 0.366). Creatinine kinase (CK) was higher after ECP compared to SCS (p < 0.001). No weight increase was observed during UW perfusion, but increased 56% during HTK perfusion. Following 12 h reperfusion, mean weight gain reduced 39% in the HTK group and increased 24% in the UW group and 17% in the SCS group. To conclude, skeletal muscle seemed well preserved after 18 h ECP with HTK or UW perfusion, with comparable histological results to 4 h SCS upon short reperfusion. The high oedema rate during HTK perfusion remains a challenge that needs to be further addressed.

VCA supercooling in a swine partial hindlimb model

“…Overall, no macroscopic difference was found between groups, despite milder ecchymoses in the supercooled grafts. When focusing on the myocyte preservation, blinded microscopic assessment of the muscle only showed statistically significant differences with lower injuries at the end of the SNMP phase (Kruit et al VCA score) 28 . Skin and nerve microscopic analyses showed no significant differences in all three groups following normothermic blood perfusion (Supplementary Fig.…”

“…Samples were fixed in 10% buffered formalin and sent to the pathology department for paraffin inclusion, slicing, and H&E staining. A double-blinded reading was performed, and a muscle injury score was used (Kruit et al 28 ) to compare the groups and the changes over time. For the final muscle samples, a mean score was calculated from the three values.…”

Sub-Zero Non-Freezing of Vascularized Composite Allografts Preservation in Rodents

“…Slides were stained with hematoxylin and eosin (H&E). A blinded evaluation by a pathologist was performed for all biopsy samples and using the muscle injury score [22][23][24]. For the muscle samples at end of recovery phase, a mean score was calculated for comparison.…”

“… ( a ) Blinded, microscopic muscle injury score [ 22 ] shows no significant differences between groups, however EG group seems to have the highest scoring trend, and 100 mM group the lowest. ( b ) Light Microscopy (LM), x100, Hematoxylin and Eosin (H&E) staining shows myocyte size variation (*), myocyte damage (§) and interstitial edema (±), especially iii.…”

24-hour Perfusion of Porcine Myocutaneous Flaps Mitigates Reperfusion Injury: A 7-day Follow-up Study

“…However, edema formation was substantially more severe in the HTK group directly after machine perfusion, compared with the UW-MPS-perfused flaps (UW-MPS -0.22 g [0%], HTK +156.5 g [53%], P < 0.001). 17 In light of this, polyethylene glycol (PEG) was added to HTK to reduce edema formation. PEG is a nontoxic polymer, which acts as colloid that shows protective properties for ischemia reperfusion injury in the liver.…”