Asko Salmi

A prospective study of changes in muscle dimensions following free-muscle transfer measured by ultrasound and CT scanning.

&NA; A retrospective study demonstrated that noninnervated free‐muscle flaps do not lose bulk when evaluated at a mean of 41 months. The purpose of the present study was to evaluate changes in muscle bulk in noninnervated freemuscle transfers prospectively. This study included 22 flaps (17 latissimus dorsi, 4 rectus abdominis, and 1 gracilis). The thickness of the muscle was measured by ultrasonography preoperatively and 2 and 6 weeks and 3, 6, 9, 12, 15, 18, and 23 months postoperatively. The volume of the muscle was measured by computed tomographic (CT) scan preoperatively and 2 and 6 weeks and 3, 6, and 9 months postoperatively. Postoperative data were normalized to the preoperation measurements. The results demonstrated that the thickness of the muscle increased by a mean of 2.4 times (range 0.9 to 3.9) compared with the initial thickness in a 2‐week period (p < 0.05), 2.0 times (range 0.9 to 4.2) in 6 weeks (p < 0.05), 1.7 times (range 0.8 to 4.2) in 3 months (p < 0.05), 1.5 times (range 0.6 to 3) in 6 months (p < 0.05), and 1.2 times (range 0.4 to 2.8) in 9 months (not significant). Thereafter, the mean thickness was the same as the initial thickness. CT scan measurements of the muscles confirmed the ultrasound findings. Our prospective study of free‐muscle flaps found significant swelling that peaks at 2 weeks and extends until 6 months after the operation. This study also demonstrated that ultrasound evaluation of thickness gives the same conclusion as volumetric measurement by CT scanning. (Plast. Reconstr. Surg. 97: 1443, 1996.)

Postoperative changes in blood flow in free muscle flaps : A prospective study

We used color Doppler ultrasound (US) to study postoperative changes in blood flow in 10 non‐innervated free latissimus dorsi (LD) muscle flaps transplanted onto lower extremities. The peak, mean, and minimum velocities, resistance index, and diameter of the pedicle, and the recipient and control arteries were recorded preoperatively and on the 2nd, 5th, and 10th days after surgery. In the pedicle of the transplant, the peak and mean velocities increased but not significantly during the follow‐up. The minimum velocity value in the thoraco‐dorsal artery was (mean ± SD) 4 ± 5 cm/sec preoperatively, and was in the leg 19 ± 9 cm/sec (P < 0.05) on the 5th and 17 ± 10 cm/sec (P < 0.05) on the 10th postoperative day. The preoperative value of the resistance index decreased from 0.92 ± 0.12 to 0.79 ± 0.08 on the 10th postoperative day (P < 0.05). In the recipient artery, the peak (117 ± 37) and mean (35 ± 16 cm/sec) velocities increased significantly on the 5th postoperative day compared to the preoperative value (79 ± 22 and 14 ± 6 cm/sec, respectively). The minimum velocity increased but not significantly. The resistance index was preoperatively 1.23 ± 0.09 and 0.88 ± 0.16 (P < 0.05) on the 10th postoperative day. This prospective clinical study demonstrates that blood flow in the pedicle and in the recipient artery of a free muscle flap increases after surgery. This phenomenon may be due to loss of vascular tone and decreased resistance after denervation. Increased blood flow helps to keep the microanastomosis open and also promotes wound healing.

Muscle fiber diameter and muscle type distribution following free microvascular muscle transfers : A prospective study

The histology of free microvascular muscle flaps in 19 patients was studied prospectively. Biopsies were taken during operation, and after 2 and 6 weeks, as well as 3, 6, and 9 months, postoperatively, fixed and stained using the van Gieson method. Fiber diameters were analyzed morphometrically and fiber types defined immunohistochemically using myosin fast antibody. During the nine‐month follow‐up period, mean muscle fiber diameter decreased significantly (P< 0.01), type‐1 fibers atrophied significantly (P< 0.05) compared to type‐2 fibers, and the percentage of type‐2 fibers increased from a mean of 56% intraoperatively to 73% at 9 months. Fatty change and fibrosis were already present 2 weeks after operation and increased with the duration of follow‐up. The decrease in muscle fiber diameter 9 months after free flap transfer correlated with clinical factors such as the delay of reconstructive surgery, recipient site, postoperative infection, and postoperative immobilization. The present results confirm that type‐specific atrophy related to denervation appears and indicates that clinical events other than denervation influence the muscle atrophy seen in human free muscle flaps. These findings focus attention on the role of muscle regeneration, reinnervation, and revascularization taking place after free flap transfer.

Effect of cooling and warming on thermographic imaging of the perforating vessels of the abdomen

Abstract The skin islands of musculocutaneous flaps are nourished by perforating arteries. An easy method for accurately locating these vessels preoperatively would be valuable in flap design. Thermography is being developed in our center as a tool to locate the perforating vessels, which appear as “hot spots” on thermographic images. The abdominal perforators of 16 women were mapped out after warming or cooling the skin with COLDI-micro thermocushions. In group I (n=8) the thermo packs were applied to the lower abdominal skin for 30 s and in group II (n=8) for 300 s. In both groups all hot spots disappeared after warming. After cooling, the hot spots were clearer and more readily visible than at room temperature. The longer cooling time (300 s) gave a 3.4 times better contrast (p=0.03) than the shorter cooling time (30 s). The longer the cooling time, the longer the hot spots were visible. This work shows that cutaneous perforators can be sharply mapped preoperatively using thermography after simple bed-side cooling.

Colour Doppler ultrasound evaluation of haemodynamic changes in free tram flaps and their donor sites.

Colour Doppler ultrasound (US) was used to measure the blood flow in the donor and recipient arteries as well as in the deep superior epigastric artery of 10 patients having free transverse rectus abdominis myocutaneous (TRAM) flaps. The peak, minimum and mean velocities, the diameter of the vessel, and the resistance index of both the deep superior and inferior epigastric arteries and thoracodorsal arteries were recorded preoperatively and at 4-6 and 15-30 days postoperatively. Colour Doppler US showed increased minimum velocity and decreased resistance index in the pedicle ( p < 0.05) throughout the follow-up when compared with the baseline. In the ipsilateral superior epigastric artery the mean and minimum velocities increased ( p < 0.05) while the resistance index decreased ( p < 0.05) during the first month postoperatively. No changes were recorded in the opposite epigastric arteries or in the control vessel (opposite thoracodorsal artery). In all patients the diameter of the deep inferior epigastric artery was larger than that of the superior epigastric and remained so after the transfer. From the fourth to the thirtieth postoperative day blood flow increased in the free TRAM flap, presumably because of decreased vascular resistance. Blood flow also increased in the superior epigastic artery on the donor side after free TRAM transfer as expected (indicating the delay phenomenon), but harvesting the flap did not affect the circulation in the opposite rectus abdominis muscle. The inferior epigastric arterial system was dominant in all patients.

Preoperative cooling and warming of the donor site increase survival of skin flaps by the mechanism of ischaemic preconditioning: an experimental study in rats.

Recent studies show that survival of skin flaps can be increased by ischaemic preconditioning with repeated cycles of ischaemia and reperfusion before prolonged ischaemia or raising of the flap. In this study three cycles of cooling and warming of rat dorsal skin were used to regulate skin blood flow and to induce three cycles of ischaemia and reperfusion. In 10 Sprague-Dawley rats three cycles of cooling (-18 degrees C ice pack) and warming (45 degrees C running water) were used to regulate skin blood flow before the flaps were raised. Caudally-based skin flaps 11 x 2 cm were then raised to the left of the dorsal midline and sutured back. In the control group (n = 9) the flap was raised and sutured back without any treatment. Viability was assessed after seven days and the survival area calculated with planimetry. Viability increased from a mean (SD) of 61 (6)% in the control group to 77 (7)% in the experimental group (p < 0.0001). This study shows that preoperative cooling and warming of the donor site can be used to increase survival of skin flaps. The probable explanation is ischaemic preconditioning although the biochemical mechanism is unclear.

Satellite cell proliferation, reinnervation, and revascularization in human free microvascular muscle flaps1

BACKGROUND Satellite cell proliferation, reinnervation, and revascularization were studied in human nonreinnervated free microvascular muscle flaps to characterize mechanisms of muscle regeneration after flap surgery. MATERIALS AND METHODS Patient biopsies (n = 19) were taken at operation and five timepoints up to 9 months after operation, and corresponding clinical data were obtained. Immunohistochemistry for Ki-67 was used to detect proliferating satellite cells, CD-31 to identify endothelial cells, and S-100 and PGP 9.5 proteins to detect reinnervation. RESULTS Two weeks after operation, the expression of PGP 9.5 and S-100 had virtually disappeared in all larger nerve fibers and half of smaller nerve fibers. By 6 months, however, a strong expression of PGP 9.5 and S-100 had reappeared in larger nerve fibers in three of four flaps, suggesting that reinnervation had taken place. The number of mitotic satellite cells already peaked at 2 weeks, indicating onset of muscle regeneration. The number of intramuscular capillaries first increased but later decreased to lower than original level. Flaps with more muscle volume showed more reinnervation and satellite cell mitotic activity. In cases of a delay occurring in reconstructive surgery, a low level of reinnervation was seen. CONCLUSION Three patients of four showed spontaneous muscle reinnervation in microvascular free flaps with satellite cell activation followed by restored morphology. Late reconstruction and obesity lead to poor reinnervation, placing emphasis on timing of surgery and patient selection.

Magnetic resonance imaging of free muscle flaps

Postoperative behaviour and changes in the structure of free microvascular muscle flaps are unknown. Magnetic resonance imaging was used to monitor postoperative structural changes in free muscle flaps. MRI was conducted on 10 patients 2 weeks and 6 months postoperatively. The results were correlated with our earlier findings using ultrasonography and computed tomography. Oedema and fat degeneration were visually assessed (scale 1–4) and T2-dependent signal intensity, flap thickness and volume were measured from the MR images. When the 2 weeks values were compared with the 6 months ones it was found that intramuscular oedema decreased from 3±0.5 (moderate) to 1.7±0.5 (slight) (p<0.05) and fat degeneration increased from 1.1±0.33 (normal) to 1.9±0.78 (slight) (p<0.05). T2-weighted signal intensity, representing postoperative inflammatory changes, oedema, and also reflecting changes induced by denervation, declined by 28%. The volume of the free flap increased by a mean of twice (from 162±81 ml to 305±135 ml) the initial values in a 2 week period (p<0.05), and attained its initial volume in 6 months (132±69 ml). The thickness of the transplant increased from 11.8±2 mm to 24±4 mm in 2 weeks (p<0.05) and decreased to 13.8±3.5 mm at 6 months. MRI also shows that a free microvascular muscle tightly fills cavities. The correlation between MRI and earlier US studies was 0.71 and between MRI and CT 0.83. MRI is an accurate but expensive research tool to evaluate noninvasively changes in free muscle flaps after the surgical procedure. A 6-month follow up, this study showed that after extensive postoperative swelling the flap attains its initial thickness. The structure of the free flap changes: muscle is replaced by fatty degeneration and also the surface of the flap becomes thicker. Signs indicating denervation induced intramuscular changes in the flap were also noted.

Breast reconstruction with free transverse rectus abdominis myocutaneous flaps in hospitals unaccustomed to microsurgery: Original retrospective study

We studied retrospectively 102 consecutive free TRAM breast reconstructions that were done outside our own hospital in hospitals that were not used to microsurgical techniques. Twenty-three patients were operated on by an uninfiltrated free TRAM technique, and 79 had 0.5% lignocaine with adrenaline infiltrated along the incision lines before the operation. We lost two flaps and six flaps developed necrosis of the medial edge. Our total complication rate (25%) compared well with those of other studies. Infiltration with lignocaine and adrenaline significantly decreased the operating time (mean (SD) 234 (91) compared with 159 (40) minutes), peroperative bleeding (930 (530) ml compared with 350 (180) ml), peroperative transfusions, and the total number of transfusions, so improving the cost:effect ratio of free TRAM breast reconstructions. Microsurgical free TRAM breast reconstructions can be done with good results in peripheral hospitals.