Early detection onset of flap failure using near infrared spectroscopy.

BACKGROUND: Near-infrared spectroscopy (NIRS) is widely used to assess flap perfusions by measuring tissue oxygen saturation (StO2). However, the StO2 level for the onset of perfusion failure is still a controversial issue. AIM: This study proposes a new threshold of StO2 level for detecting the onset of perfusion failure as early as possible to increase flap salvage rates. METHODS: Twenty patients undergoing flap surgery were included in this study - 13 flaps were implemented to cover defects that occurred due to trauma and 7 flaps to hide imperfections that occurred after cancer treatment. Thirteen flaps were in the lower extremity, six in the mandible, and one in the breast. NIRS was used to measure StO2 in 240 flap regions of the 20 patients to determine flap viability using descriptive statistics. RESULTS: The mean StO2 values from healthy flap and control regions were obtained as 81.6% ± 0.36 and 82% ± 0.18, respectively. The lowest StO2 value of 77.2% was defined as the onset of a vascular complication at a probability of 99.74% by subtracting three times the standard deviation from the mean StO2 of healthy flaps. Vascular complications were observed from 21 regions in the four flaps with StO2 values lower than 77.2%, but only one was lost. CONCLUSION: The threshold value for the onset of perfusion failure was a 5% decrease from the expected value, much lower than previously described thresholds that may facilitate the detection of perfusion failure in the early stage and increase salvage rates in flap revisions.

Does ischemic preconditioning increase flap survival by ADORA2B receptor activation?

BACKGROUND: Ischemic preconditioning (IPC) is defined as raising tolerance to subsequent ischemic stress by exposing tissues to sub-lethal ischemia. Although many candidates have been suggested, recent studies have clearly demonstrated that adenosine-mediated ADORA2B receptor (ADORA2BR) activation is the main mechanism involved in IPC. While the tissue-protective role of this mechanism has been demonstrated in different ischemia/reperfusion (I/R) models, its role in flap surgery-derived I/R damage has not to date been investigated. OBJECTIVE: To investigate the role of adenosine and ADORA2BR activation in IPC-mediated tissue protection in an epigastric flap model. METHODS: Animals were divided into five main groups, all of which were then divided into two subgroups depending on whether or not they were exposed to IPC before the I/R procedure, which consisted of 6 hours of ischemia and 6 days of reperfusion. No drugs were administered in Group 1 (the control group). Animals in Group 2 were pretreated with CD73-inhibitor before IPC application or the ischemic period. Animals in Group 3 were pretreated with adenosine. Animals in Group 4 were pretreated with an ADORA2BR antagonist, and those in Group 5 with an ADORA2BR agonist. After 6 days of reperfusion, tissue survival was evaluated via histological and macroscopic analysis. RESULTS: IPC application significantly enhanced CD73 expressions and adenosine concentrations (p < 0.01). Flap survivals were increased by IPC in Group 1 (p < 0.05). However, CD73 inhibition blocked this increase (Group 2). In Group 3, adenosine improved flap survival even in the absence of IPC (p < 0.01). While an ADORA2BR antagonist attenuated the tissue-protective effect of IPC (p < 0.01), the ADORA2BR agonist improved flap survival by mimicking IPC in groups 4 and 5. CONCLUSION: These results provide pharmacological evidence for a contribution of CD73 enzyme-dependent adenosine generation and signaling through ADORA2BR to IPC-mediated tissue protection. They also suggest for the first time that ADORA2BR agonists may be used as a potential preventive therapy against I/R injury in flap surgeries.

Experiences with functional gracilis muscle flap in lower lip reconstruction.

OBJECTIVE: Reconstruction of the lips is pivotal because the lips play an essential role in facial aesthetics and have unique functional properties. We presented our experience in reconstruction of total or subtotal lower lip defects with functional gracillis muscle flap covered split-thickness skin graft (STSG) in patients. METHODS: Between 2009 and 2011, seven patients underwent resection of lower lip squamous cell carcinoma and lip reconstruction. Gracillis muscle flap was performed for reconstruction. Recipient vessels were the facial artery and vein. Motor nerve of the gracillis muscle was coapted to the marginal branch of the facial nerve. Gracillis muscle was covered with STSG. Patients were evaluated about mouth opening, oral competence, word articulation, the color match of the graft, the contraction of the muscle by physical examination. Electromyographic studies and sensation tests were performed. RESULTS: Postoperative course was uneventful for all of the flaps. No microvascular revisions were needed. One patient was reoperated because of wound dehiscence under local anaesthesia. Mean follow up period was 15 months. After three months, movement of the reconstructed lip was observed. Color of the grafted skin was matched with the skin of the face. The patients had no problems with word articulation, oral continence, or mouth opening. The electromyographic study showed recovery of motor innervation. After 1 year, the patients demonstrated recovered sensitivity with the sensation test. CONCLUSION: Considering functional results, superior aesthetic appearance, and minimal donor-site morbidity of the functional gracillis transfer covered skin graft, we think that this method may be an alternative for reconstruction of large full-thickness defects of the lower lip. © 2015 Wiley Periodicals, Inc. Microsurgery 37:487-493, 2017.

Reconstruction of midfoot bone and soft tissue loss with chimeric partial scapula and latissimus dorsi muscle flap and short perforator-based skin flap following gunshot injuries: Report of two cases.

INTRODUCTION: In this report we present two cases of gunshot injury related midfoot defects, reconstructed with a chimeric partial scapula and latissimus dorsi muscle flap and short perforator-based skin flap. The first case, a 14 years old male, had 10 × 8 cm medial plantar and 6 × 4 cm dorsal foot defects and the second case, a 55 years old female, had only 8 × 6 cm dorsal foot defect. In both cases the defects were associated with fractures, one with lateral cuneiform and cuboid with 90% bone loss and the other with navicular bone, respectively. After 6 months, the patients could walk well without support, and radiographs confirmed bony union. A chimeric partial scapula and latissimus dorsi muscle flap and short perforator-based skin flap may be used for the reconstruction of combined bony and soft tissue defects of the midfoot and to promote bone healing. © 2016 Wiley Periodicals, Inc. Microsurgery 36:598-603, 2016.

The Effect of Normovolemic and Hypervolemic Hemodilution on a Perforator Flap with Twisted Pedicle Model: Experimental Study in Rats.

BACKGROUND: Several studies showed the detrimental effect of pedicle torsion on flap survival; however, the impact of hemodilution in this peculiar condition has never been investigated. This study evaluated the effect of acute normovolemic and hypervolemic hemodilution on flap survival in a perforator flap with twisted pedicle model. METHODS: Sixty-three female Wistar rats were divided into three groups of 21 rats each: group 1, superficial inferior epigastric artery flap, which was elevated bilaterally and transposed back to the abdominal wall with different angles of rotation (i.e., 90, 180, 270, and 360 degrees); group 2, surgery with previous acute normovolemic hemodilution; and group 3, surgery with previous acute hypovolemic hemodilution. Normovolemic hemodilution was obtained, simultaneously removing 2 cc of blood and replacing it with an equal volume of isotonic sodium chloride 0.9% (two-thirds) plus hydroxyethyl starch 6% (one-third). Hypervolemic hemodilution was obtained by hemodilution and a 20 percent blood volume expansion. Microangiography of the flap and histopathologic analyses were performed. RESULTS: Mean hematocrit values after hemodilution were 27.80 ± 0.04 percent for the acute normovolemic hemodilution group and 27.01 ± 0.03 percent for the acute hypovolemic hemodilution group. Twisting the pedicle at 90, 180, and 270 degrees had no effect on flap survival in all groups. However, 360-degree pedicle torsion showed flap edema, congestion, and necrosis. CONCLUSIONS: The authors' hemodilution protocol is an effective and reliable method that could be used to further investigate the impact of the hemodynamic changes that occur during hemodilution on flap microcirculation. The results obtained sustain the existence of a strong correlation between necrosis rate and hemodilution.

The Effect of Normovolemic and Hypervolemic Hemodilution on a Microsurgical Model: Experimental Study in Rats.

BACKGROUND: Nowadays, postoperative flap perfusion impairment still occurs in free flap surgery; despite several studies on microcirculatory physiology, the effect of hemodilution is still extremely controversial. The aim of this study was to investigate the impact of acute normovolemic and hypervolemic hemodilution on the incidence of flap survival rate in a microsurgical rat model. METHODS: Forty female Wistar rats were divided into four groups of 10 rats each: in group 1, a superficial inferior epigastric artery flap was elevated until femoral vessels were isolated, sectioned, and anastomosed without hemodilution; in group 2, surgery with previous acute normovolemic hemodilution was performed; in group 3, surgery with previous hypervolemic hemodilution was performed; and group 4, was used as a negative control to validate the microsurgical model. Normovolemic hemodilution was obtained, with simultaneous removal of an average of 2.25 cc of blood and replacement with an equal volume of isotonic sodium chloride 0.9 percent and hydroxyethyl starch 6 percent. Hypervolemic hemodilution was obtained by hemodilution and a 20 percent blood volume expansion. Microangiography of the flap and histopathologic analyses were performed. RESULTS: Mean hematocrit values after the hemodilution were 26.80 ± 0.05 percent for group 2 and 28.11 ± 0.04 percent for group 3. Skin flap survival and vascularization after 7 days were significantly higher in both hemodiluted groups compared with the control group (p < 0.05). CONCLUSION: Hemodilution was an effective way of providing better microcirculatory blood perfusion, increasing significantly the flap survival rate in the authors' microsurgical model.