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Biomedical subjects

P Hedén

Publications and source records attributed to P Hedén.

At least 19 recordsLinked to original sources
PubMed2001

Breast augmentation with anatomical cohesive gel implants: the world's largest current experience.

Anatomic cohesive silicone gel implants in breast augmentations require a considerably different technique compared with standard round implants. If the dimensions and proportions of the thorax and breast and thus the prerequisite for different implant shapes are evaluated adequately, this newer technique can lead to highly predictable results with a high degree of patient satisfaction.

Breast Implants↗
PubMed2000

Prediction of border necrosis in skin flaps of pigs with microdialysis.

Metabolic changes were studied in newly-raised pedicled skin flaps of pigs. These flaps were constructed so that their distal parts were predestined to necrotize. The objective was to find new ways of making early postoperative prognostications about future flap viability. For that purpose, the fluorescein penetration technique was compared with microdialysis monitoring of interstitial tissue concentrations of glucose, lactate, and glycerol. These parameters were measured 6 to 24 hr postoperatively, and collected at five different sites, ranging from base to end of the flap. The fluorescein penetration border appeared closer to the flap base than a subsequent necrotic border, thereby confirming that this technique--when applied early in the postoperative period--underestimates flap viability. The authors also observed that glucose concentration in the flap declined at an early stage close to the border of fluorescein penetration. No further change was seen in more distal parts of the flap. Consequently, glucose concentration underestimates the viable flap area just as fluorescein does. In contrast, both glycerol and lactate concentrations began to increase closer to the necrotic border. Both increased significantly on passing the border between viable tissue and tissue which later on would become necrotic, and reached levels in the necrotic portion which were never seen in the viable parts. These results were obtained within the first postoperative hours. They suggest that microdialysis monitoring of lactate and glycerol concentrations in skin flaps of pigs can be used to estimate at an early stage where the necrotic border will appear later on. If these results hold true in humans, they may have important clinical applications.

Animals↗
PubMed1995

Effects of calcitonin gene-related peptide and lidocaine on mechanically-induced vasospasm in a rat island flap.

A neurovascular island flap based on the superficial epigastric vessels was raised in 59 rats. Blood flow in the flap was recorded continuously with a laser Doppler flowmeter. Complete vasospasm was induced mechanically in the artery by pinching it. Calcitonin gene-related peptide (10(-7) M), lidocaine 2 percent, lidocaine 20 percent, or sodium chloride 0.9 percent were applied topically to the vessels in order to relieve the vasospasm. In 18 arteries, spasm was induced a second time after the resolution of the first vasospasm. Calcitonin gene-related peptide significantly shortened the time to reach 50 percent of the original blood flow and increased the final blood-flow values 30 min after mechanically-induced vasospasm, in comparison with pre-spasm values, and significantly increased the number of flaps in which the blood-flow values were restored to pre-spasm levels. Lidocaine did not significantly change the time to reach 50 percent of the original blood-flow values and the number of flaps recovering to pre-spasm blood-flow levels, or the final levels after vasospasm, in comparison with saline. It was concluded that, in this model, calcitonin gene-related peptide, but not lidocaine, increased blood flow after mechanically-induced vasospasm.

Animals↗
PubMed1993

Circulation of blood and viability after blunt suction lipectomy in pig buttock flaps.

Bilateral buttock flaps were raised in 13 Yorkshire pigs, and the viability and superficial blood flow were assessed by injection of fluorescein and laser Doppler flowmetry. One flap was then chosen at random from each pig to be defatted by blunt suction lipectomy. The opposite flap served as the control. Five and 30 minutes after lipectomy, the experimental flaps showed a 31% and 37% decrease in laser Doppler values (p < 0.05 and p < 0.01, respectively), measured 6 cm proximal to the margin of the fluorescein dye. There was no reduction in the values in the controls. One week after liposuction, the median area of flap necrosis in treated flaps was 4,615 mm2 (range 735-6,748) and in controls 4,104 mm (1,576-5,879). This difference was not significant (p = 0.24). Blunt suction lipectomy of the skin flaps did not significantly decrease the viability. The decreased skin circulation shown by laser Doppler soon after lipectomy may be a minor or temporary phenomenon.

Animals↗
PubMed1992

A triangular cutting arteriotomy scissors facilitating end-to-side anastomoses.

A new microsurgical triangular cutting scissors facilitating end-to-side anastomoses has been developed. The instrument removes oval pieces of tissue from the vascular wall with a single cut. This has several advantages over conventional double cuts with straight microscissors. Preferential use of end-to-side anastomoses has been advocated by several authors, one of the main reasons for this being preservation of the distal blood flow in the artery used in the recipient bed. It also has been reported that vascular occlusions are less frequent with this type of coupling. Another important indication for end-to-side anastomoses is a significant discrepancy in vessel size. One of the more demanding tasks in making an end-to-side anastomosis is the performance of a perfect arteriotomy. With the aim of facilitating the arteriotomy in end-to-side anastomoses, a new microsurgical instrument has been developed.

Anastomosis, Surgical↗
PubMed1992

Endothelin reduces blood flow in experimental skin flaps.

An island buttock flap based on the deep circumflex iliac artery and vein was raised in four pigs. Cutaneous laser Doppler blood flow (LDF) and total venous outflow (VO) from the flaps were measured. Intra-arterial infusion of endothelin-1 (0.3-2.5 nmol) through a branch of the deep circumflex iliac artery induced a pronounced and long lasting decrease in both LDF and VO. The maximal mean reductions being 95.3% and 73%, respectively, were seen within 5 minutes of the infusion. Intra-arterial infusions of endothelin in the circumflex iliac artery on the contralateral side caused a considerable reduction in intact skin LDF. Endothelin has potent vasoconstricting properties and its possible release and effect must be considered in reconstructive surgery.

Animals↗
PubMed1992

Temperature load test to increase the accuracy of laser Doppler monitoring of flaps.

A heat and cold provocation test was evaluated in 10 porcine island flaps to improve the quality of monitoring flap circulation by the laser Doppler technique. When the pedicle blood flow was undisturbed there were significant increases in flow after a heat stimulus (p = 0.01), whereas no significant flow changes were noted during arterial or venous occlusion. This method can increase the accuracy of the laser Doppler technique in monitoring the circulation in skin flaps.

Animals↗
PubMed1992

A new and simple way to clear the hair from operating fields in the scalp.

The McGivney instrument has been designed for rubber band ligation of hemorrhoids. A simple way to clear the hair from the operating field with the aid of this device during surgery on the scalp is described. The method has been found to be quick and easy, and the tuft of hair is also held in a firmer position than with other methods used for this purpose.

Equipment Design↗
PubMed1991

Presuturing in rhytidectomy: a case report.

The use of intraoperative tissue expanders or staged skin excision to improve the results of facelift surgery has been previously reported. However, it is debatable whether excess skin excision improves the final result of rhytidectomy. To determine whether increased skin excision without increased skin tension on the suture line could improve the final results of facelift surgery, a unilateral presuturing technique was used on one patient. Equal bilateral skin tension at the suture line, checked with a spring dynamometer, resulted in a marked increase in the amount of skin excised on the presutured side. No significant difference was noted initially after the operation, but the results at six weeks and at one year after surgery were felt by both patient and physician to be slightly better on the presutured side.

Aged↗
PubMed1991

Circulatory and metabolic changes in expanded pig skin flaps.

To evaluate circulatory and metabolic changes in pig skin during tissue expansion, the buttock skin of 12 pigs was expanded for 5 weeks. In a second operation, island buttock flaps were elevated bilaterally. Flap temperature, laser Doppler flow (LDF), and fluorescein penetration borders were recorded. Norepinephrine infusions were given twice. After cannulation of the external iliac veins, the total venous outflow from the flaps and metabolic parameters such as glucose and oxygen consumption and lactate production were measured bilaterally. No significant difference in fluorescein staining was found, but laser Doppler flow in the expanded tissue was higher than in nonexpanded skin, whereas the total flap blood flow was not significantly different. A flow reduction was seen in expanded flaps during norepinephrine infusion, whereas nonexpanded flaps showed a slightly increased blood flow. This adrenergic supersensitivity indicates that it is possible that not only surgical nerve section but also tissue expansion can result in sympathetic denervation. No differences in the metabolic parameters were observed.

Animals↗
PubMed1991

Small accumulation of inosine monophosphate (IMP) despite high lactate levels in latissimus dorsi during transplantation.

The effects of prolonged ischaemia and subsequent reperfusion during and after reconstructive microsurgery on energy metabolism were studied. Repeated skeletal muscle biopsies were taken and analysed for high energy phosphates and their degradation products by high performance liquid chromatography and for lactate by a fluorometric procedure. Moderate changes in adenine nucleotides occurred during the first 4 h of ischaemia. After 6 h of ischaemia, when the creatine phosphate store was almost depleted and the lactate level had increased to 111 mmol kg-1 dry muscle, ATP content decreased and inosine monophosphate started to accumulate. The inosine monophosphate accumulation was however small, in spite of a high lactate level, which suggests that the increase in H+ associated with lactate formation is not important for the activation of AMP-deaminase during the present conditions. In spite of the accelerating metabolic deterioration during the later period of ischaemia, the reperfusion of the muscle resulted in a rapid normalization of all the studied metabolites, thereby indicating a rapid restoration of the muscle energy stores.

AMP Deaminase↗
PubMed1989

Circulatory and metabolic events in pig island skin flaps after arterial or venous occlusion.

After 1 hour of arterial or venous occlusion, the circulatory and metabolic events in island skin flaps of the pig were studied. Both occlusion types showed significant but transient increases in glucose uptake and a parallel release of lactate, hypoxanthine, and potassium. Oxygen uptake and noradrenaline release were not significantly affected. No significant difference between the arterial and venous occlusions was seen in the metabolic parameters. The flap blood flow, measured by total venous outflow and laser Doppler flowmetry, was significantly lower after venous than after arterial occlusion. This long-lasting difference in flow response may help to explain the observation that venous occlusion is more deleterious to skin flaps than arterial occlusion. A mechanism underlying these results may be more pronounced microthrombotization and/or edema formation after venous occlusion than after arterial occlusion.

Animals↗
PubMed1989

Skin flap circulation. Simultaneous monitoring with laser Doppler and electromagnetic flowmeters in the pig island buttock flap.

Twenty-two island skin flaps based on the deep circumflex iliac vessels were elevated in pigs. A comparative study of Laser Doppler flowmetry (LDF) and electromagnetic flowmetry (EMF) was undertaken. Flow values were compared during selective arterial and venous occlusion, nerve stimulation and intra-arterial noradrenaline or papaverine injection. The effectiveness of flap temperatures and blood gas data in monitoring vascular occlusions was also investigated. Similar and simultaneous responses in LDF and EMF values were noted during the different experimental manipulations, but for single simultaneous LDF/EMF observations from different animals the correlation coefficients were poor. The accuracy of EMF measurements in monitoring total flap inflow was confirmed by a high correlation with total venous outflow values. Major vascular occlusions also resulted in significant changes in the flap temperatures, and in the flap blood gases.

Animals↗
PubMed1989

Increased skin flap survival and arterial dilation by calcitonin gene-related peptide. A study in the pig.

Calcitonin gene-related peptide (CGRP), a recently discovered neuropeptide, is a potent vasodilator and increases blood flow in many vascular beds. The effect of CGRP treatment was investigated in critical pig pedicle and island flaps. Prior to pharmacological treatment the peroperative circulation border was estimated with fluorescein. Intradermal or intraarterial flap treatment with CGRP was given. Control flaps were untreated or injected with saline. Increased or decreased survival was calculated as the difference between the peroperative fluorescein penetration border and the survival border one week after surgery. CGRP treatment significantly increased the survival of both random pedicle and island flaps. CGRP doses as low as 3 ml x 10(-14) M (equal to 0.03 fmoles) increased the survival of random pedicle flaps. In 4 untreated pigs the deep circumflex iliac arteries were excised and artery ring preparations were studied in vitro. A dose-dependent relaxation of artery rings was noted between 10(-9) M and 10(-7) M CGRP.

Animals↗
PubMed1989

Sensory denervation with capsaicin does not influence the critical ischemia time in rat island flaps.

Capsaicin causes release and long-term depletion of neuropeptides from sensory neurons. Recently, critical rat pedicle flaps pretreated with capsaicin have shown decreased survival. In the present study, the effect of systemic capsaicin pretreatment on the no-reflow phenomenon was investigated in the rat. Effective depletion of neuropeptides was confirmed with functional tests and immunohistochemistry. Groin island flaps were exposed to 4, 6, 8, 10 or 12 hours of warm ischemia, and flap survival was judged one week postoperatively. In contrast to previously reported negative effects on pedicle flap survival after pretreatment with capsaicin, the present study showed no difference in flap survival between capsaicin-pretreated rats and controls. It is concluded that depletion of neuropeptides from sensory neurons does not have negative effects on the tissue's ability to withstand prolonged complete ischemia. As this contrasts with the findings in critical pedicle flaps, the influence of sensory neuropeptides and the necrosis mechanisms are likely to be different in these two types of ischemic conditions.

Animals↗
PubMed1989

Treatment of keloids with surgical excision and postoperative X-ray radiation.

124 patients with keloids were treated with surgical excision followed by postoperative X-ray radiation, begun within 24 hours after surgery. Only patients with a two-year keloid history were included in this study. The treatment results were evaluated 6 and 24 months after treatment. There was good correlation agreement between subjective and objective evaluations. Good or excellent results were observed in 92% of the patients. Side effects were moderate. Slight hyperpigmentation was found in 31% of the patients and telangiectasis in 15%. It was concluded that excision and early postoperative irradiation constitute effective keloid treatment.

Adult↗
PubMed1989

Early circulatory and metabolic events in island skin flaps of the pig.

Circulatory and metabolic skin-flap events were studied prior to and up to 6 hours after elevation of buttock island flaps in pigs. During the elevation, significant reductions in superficial skin blood flow, measured by laser Doppler flowmetry (LDF) and dermal flap temperature, were seen. Significant correlations were found between blood flow and temperature. Total flap blood flow, measured as venous outflow, also showed an initial transient decrease, but 2 hours after flap construction, venous outflow had returned to preoperative values. A significant increase in lactate release, together with increased oxygen consumption and glucose uptake, was seen 4 hours after the surgical intervention. Hypoxanthine release, indicating ischemia, was seen only during the first hour after flap elevation. Noradrenaline outflow was noted after 4 and 6 hours, but there was no parallel reduction in flap blood flow. A great deal of the flow reduction in acutely elevated island flaps may thus be due to primary hypothermia rather than to the degenerative release of noradrenaline, which seems to have no early effect on skin flap blood flow. On the other hand, the noradrenaline release may be linked to an increased metabolic activity in the skin flaps.

Animals↗