• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.29.1-29.7
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• 2020

Background: Microvascular reconstruction is the treatment of choice after oral cancer ablation surgery. There are few published studies of free flap survival among Korean populations. This study aimed to determine the survival rate after 121 consecutive cases of maxillofacial microvascular reconstruction and to analyze the complications associated with microsurgery. Methods: This study included consecutive patients who underwent microsurgical reconstruction with free flaps, from January 2006 through September 2019, performed by a single surgeon at the oral and maxillofacial surgery department of a tertiary medical center. A total of 121 cases were reviewed retrospectively. The flap survival rate, flap type, radiotherapy history, complications, and treatment results were analyzed. Results: Four different flap types were used for microvascular reconstruction: radial forearm (n = 65), fibula (n = 34), latissimus dorsi (n = 21), and serratus anterior muscle with rib bone free flap (n = 1). Total necrosis of the flap was found in four cases (two latissimus dorsi flaps and two fibular flaps). The free flap survival rate was 97.5%. Nineteen patients received radiotherapy before surgery, and none of them experienced flap failure. The mean operation time was 334 ± 83.1 min, and the mean ischemic time was 48.9 ± 12.7 min. Conclusions: The success rate was reliable and comparable with previous studies. The success rate was not affected by radiation therapy. Free flaps can be safely used even after radiation treatment.

• Archives of Craniofacial Surgery
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• v.22 no.1
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• pp.38-44
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• 2021

Background: The free flap surgical method is useful for the reconstruction of head and neck defects. This study retrospectively analyzed the results of head and neck reconstructions using various types of free flaps over the past 30 years. Methods: Between 1989 and 2018, a total of 866 free flap procedures were performed on 859 patients with head and neck defects, including 7 double free flaps. The causes of vascular crisis and salvage rate were analyzed, and the total flap survival rate calculated among these patients. Additionally, the survival and complication rates for each flap type were compared. Results: The 866 cases included 557 radial forearm flaps, 200 anterolateral thigh flaps, 39 fibular osteocutaneous flaps, and 70 of various other flaps. The incidence of the vascular crisis was 5.1%; its most common cause was venous thrombosis (52.3%). Salvage surgery was successful in 52.3% of patients, and the total flap survival rate was 97.6%. The success rate of the radial forearm flap was higher than of the anterolateral flap (p< 0.01), and the primary sites of malignancy were the tongue, tonsils, and hypopharynx, respectively. Conclusion: The free flap technique is the most reliable method for head and neck reconstruction; however, the radial forearm free flap showed the highest success rate (98.9%). In patients with malignancy, flap failure was more common in the anterolateral thigh (5.5%) and fibular (5.1%) flaps.

• Archives of Craniofacial Surgery
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• v.16 no.2
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• pp.73-79
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• 2015

Background: Alprostadil and sildenafil are known vasodilators used independently to improve flap survival in animal models. In this study, we investigate whether these agents act synergistically to decrease flap necrosis in rat models. Methods: After acclimation period, 4 groups of 10 male white rats were given a modified McFarlane skin flap. The postoperative treatment included saline control (Group A), sildenafil citrate-only (Group B), alprostadil-only (Group C), and both sildenafil and alprostadil (Group D). The flaps were observed on postoperative days 1, 3, 5 and 7. The animals were euthenized on postoperative day 7, and the flaps were evaluated for inflammation and neovascularization. Results: At each observation, the mean necrotic index was significantly lower for all three treatment groups (Groups A, B, C) and was the lowest for the combined treatment group. On histologic evaluations, combined treatment was associated with decreased inflammation and increased capillary vessel formation, when compared with control group. Conclusion: Both sildenafil-only and alprostadil treatments were independently associated with increased flap survival rate. Sildenafil citrate and alprostadil had a synergistic effect in increasing flap survival rate.

• Archives of Reconstructive Microsurgery
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• v.16 no.2
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• pp.57-62
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• 2007

Non-vascularized free composite graft is one of the simple and effective reconstructive options, but its clinical use has been limited due to questionable survival rate. Early vascularization is essential for graft survival and is mainly carried out via recipient bed or repaired sites. This study was designed to investigate the effect of the lateral marginal approximations on the survival of the free composite flap using a model of skin-subcutaneous composite graft in rats. Thirty 1.5 ${\times}$ 1.5 $cm^2$ sized square shape composite flaps were elevated freely and reposed in place immediately on the dorsum of five Sprague-Dawley rats, and divided into five groups of six flaps. In all groups, graft bed was isolated with silastic sheet. In the group I, all sides of flap were repaired with blockage of silastic sheet insertion. Three, two, and one sides of flap were treated with same method in the group II, III, and IV respectively. Other sides of flaps were repaired without blockage, so all sides of flap were repaired in the group V. At 14 days later, the survived rate of each flap was evaluated according to the numbers of the repair sites. Histological examination was done for the evaluation of new vessel development quantitatively. Overall survived rates were increased with the number of repaired sites, but the group V only showed increased survival rate up to more than fifty percentile of the flap size with a significant difference statistically. New vessels were also increased in proportion with the number of repaired sites, and the repair site more than two had significant effect on the increased number of new vessels. In conclusion, at least more than three-fourth of flap circumference should be repaired in order to increase flap survival effectively under the condition of bed isolation.

• Archives of Reconstructive Microsurgery
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• v.5 no.1
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• pp.16-23
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• 1996

The omental pedicle based on right gastroepiploic vessels is designed new experimental model for prefabrication(revasculirization) of skin flaps in rats. A $2.5{\times}4cm$ pack of omentum with right gastroepiploic vessels was transferred under a bipediceld panniculocutaneous flap which is $2.5{\times}8cm$ size. At day 7, all four margin was divided and the flap was rasied as an secondary island flap connected only by its vascular pedicle, then the composite flap sutured back in place. The flap perfusion was examined by dermofluorometry and flap survival area was measured at day 12. The Secondary island flap demonstrated a dye fluorescence index(DFI%) of $31.38{\pm}12.33$ and survival rate $80.47{\pm}9.61$ The survival rate was increased when DFI% and contact surface between vascular carrier and skin flap was increased. An india ink injection and histologic examination provided visual evidence of revasculization. The omental pedicle is a promising and safe model for revasculirization of other tissues.

• Archives of Reconstructive Microsurgery
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• v.14 no.2
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• pp.95-104
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• 2005

The aim of this study was to investigate the major vascular system to supply flap, flap survival rate and complications after flap elevation in order to evaluate possibility of the vascularized face/scalp allotransplantation. Forty New Zealand white rabbits were divided into two groups: control group and experimental group. Individuals of control group had a face/scalp composite unit which was composed of skin, subcutaneous tissue and platysma muscle, supplying by bilateral facial artery, temporal artery and auricular artery and draining by external jugular vein. After a flap was elevated, bilateral facial artery, temporal artery and auricular artery were ligated. On the other hand, those of experimental group had the same composite unit as control group with bilateral facial artery, temporal artery and auricular artery being not ligated. We had measured survival area of flaps of the sixteen individuals survived for four weeks in the control group and fourteen in the experimental group by Grid method. The mean survival durations of the flap were 3.7days in the control group, 20.0days in the experimental group. The significant differences in the mean survival durations and survival rate at the 28days were found between the control and experimental group (p<0.05). Mean values about the survival area's fractions of all were $1.3{\pm}4.%$ in the control group and $63.1{\pm}4.8%$ in the experimental group. Those of experimental group was significantly higher than control group statistically (p<0.05). The composite face/scalp flap which we have elevated, supplied by bilateral facial artery, temporal artery, auricular artery and drained by external jugular vein has flap viability enough to be transplanted after its elevation.

• Archives of Reconstructive Microsurgery
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• v.6 no.1
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• pp.1-8
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• 1997

Recently prostaglandin $E_1(PGE_1)$ has been shown to ensure flap survival by producing vasodilation of the peripheral vessels and platelet disaggreation. However, direct observation and detailed quantitative studies of the effects of $PGE_1$ on the cutaneous microcirculation have not been reported. In the present study, we investigated cutaneous microcirculatory changes in the rabbit ear chamber(REC) with an intravital microscope following intravenous administration of $PGE_1$. The results obtained in this study indicate that $PGE_1$ administered intravenously at a rate of 200ng/kg/min might act directly on the vessels and cause dilatation of metarterioles and capillaries without affecting vasomotion and systemic blood pressure. Clinically in order to evaluate the effect of an intravenous administration of $PGE_1$ on the cutaneous microcirculation, cutaneous blood flow, skin temperature and transcutaneous $Po_2$ in the pedicle or free flap of operated patients were evaluated by the combination of several measurements following the administration of $PGE_1$. The present study suggests that improvement of cutaneous microcirculation by $PGE_1$ may enhance the survival rate of flap or replantation. Both vessel arterial ischemia and venous congestion are main factors of tissue necrosis in the flap surgery. Vasodilatory or antithrombotic agents have been used in salvage of flap necrosis. However, the therapeutic effects of those drugs are still not well elucidated. Recently prostaglandin $E_1(PGE_1)$ has been shown to ensure flap survival by producing vasodilatation of the peripheral vessels and platelet disaggregation[1-3]. Emerson and sykes[4] have obtained significant improvement in the flap survival in the rat using $PGI_2$. Suzuki et al.[5] have reported prolonged flap survival length by using $PGE_1$ in the rabbit and concluded that $PGE_1$ improved the microcircuration in the flap. However, direct observation and detailed quantitative studies of the effects of $PGE_1$ on the cutaneous microcirculation have not been reported. In the present study, we investigated microcirculatory changes in the rabbit ear chamber[6,7] with an intravital microscope following intravenous administration of $PGE_1$.

• Archives of Plastic Surgery
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• v.32 no.1
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• pp.5-11
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• 2005

Prostaglandin $E_1$($PGE_1$) is known to have various physiological action such as vasodilatation, decrease of blood pressure, angiogenesis, inhibition of platelet aggregation and so forth. $PGE_1$ has been developed in many different formulations in order to overcome its chemical instability and deactivation in the lungs when administered parenterally. Lipo-AS013 is a potent drug with higher chemical stability and greater vascular wall targeting than others. The study was done on $3{\times}10cm$ model flap of dorsal skin of Sprague-Dawley rats and the flap perfusion survival were observed and documented. The flap treated with Lipo-AS013 beforehand was given intravenously Sodium fluorescein 10 minutes later, and then Percent Dye Fluorescence Index(% DFI) was calculated. The results were compared to a control group and the group administered locally epinephrine.. In the control group, the % DFI and flap survival rate increased from $54.1{\pm}6.7$ to $65.0{\pm}2.6$(p<0.01) while in Lipo-AS013 group from $55.3{\pm}2.2$ to $67.4{\pm}1.9$(p<0.01), respectively. In the epinephrine group, the % DFI(p<0.05) and flap survival rate(p<0.001) decreased. In the both epinephrine and Lipo-AS013 group Percent DFI and flap survival rate are comparable with the control group.The result indicates that the potent Lipo-AS013 enhances the blood flow and flap survival. This highly potent Lipo-AS013 may have targeting ability and accumulate $PGE_1$ onto the vascular walls. A quantitative analysis of fluorescence on the skin surface is a reliable tool to measure the blood perfusion into an ischemic flap and its viability. Further comparative study with conventional $PGE_1$ and Lipo-$PGE_1$ is needed in order to clarify the action and efficiency of Lipo-AS013.

• Archives of Plastic Surgery
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• v.32 no.3
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• pp.319-326
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• 2005

This study was designed to investigate the optimal period of pedicles implantation in the prefabricated periosteofascial flap using a vascular tissue transfer. Flap prefabrication was prepared with a transposition of the central pedicles of right auricle on the calvarium of the New Zealand white rabbit. Thirty flaps were divided into five groups of six flaps, including control group (group I) of the conventional periosteofascial flap based on the right lateral border of parietal bone. The prefabricated flap was elevated as a $2{\times}2cm$ sized island flap and reposed in place in 1, 2, 3, and 4 weeks after the pedicles transfer in groups II, III, IV, and V, respectively. Five days after flap repositioning, the flap viability and vascularity were evaluated with microangiography and histological study quantitatively. The flap survival was increased in accordance with the implanted period of the pedicle. New vessels developed around the implanted pedicle in the 2nd week, and overall vascularization of the flap was accomplished in the 3rd week. The flap with 4 weeks of implantation period, however, showed the same survival rate as the control group. In conclusion, prefabricated periosteo- fascial flap can be created with a vascular tissue transfer, and the optimal duration of the pedicle implantation is more than 4 weeks to obtain adequate flap survival.

• Archives of Plastic Surgery
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• v.37 no.5
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• pp.547-554
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• 2010

Purpose: The purpose of this study is to delineate the optimal time of venous revascularization for preventing the flap necrosis due to venous occlusion, and to clarify the usefulness of tissue oxygen pressure ($TcpO_2$) in the determination of the point of time for venous revascularization. Methods: Thirty-six, $3{\times}3\;cm$ sized epigastric island flap was elevated in left abdomen of male Sprague-Dawley rat weighing 250 gram. Flaps were randomly assigned to six groups of six flaps according to the duration of venous occlusion with microvascular clamp; 10 minutes in the group I as the control, 60 minutes in the group II, 2 hours in the group III, 3 hours in the group IV, 4 hours in the group V, and 6 hours in the group VI, respectively. Just before removal of clamp after flap was reposed in situ, the ratio of $TcpO_2$ (tissue oxygen pressure) of the island flap to that of right abdomen was calculated in each group, and tissue specimen was harvested from the distal area of the flap for histological evaluation of vascular change. Five days later, survival area of the flap was estimated, and evaluated the correlation between the tissue oxygen pressure and the rate of flap survival. Results: The $TcpO_2$ and the survival rate of flap were decreased proportionally with the duration of venous occlusion. The ratio of the $TcpO_2$ of the flap is decreased abruptly to below sixty percentile compared to the $TcpO_2$ of normal tissue, and the survived area of the flap is decreased to nine-tenth of the designed size after three hours of total venous occlusion. Histologically, the number of congested vessels was increased according to venous occluded time, and proportionally increased after 3-hours of occlusion significantly. Conclusion: There is a close correlation between the $TcpO_2$ and the survival rate of flaps according to the duration of venous occlusion. Therefore, the $TcpO_2$ represents the hemodynamic changes within the flap, and thought to be an alternative effective tool in the flap monitoring for venous revascularization.