Dorthe Kjølseth

The microcirculation of myocutaneous island flaps in pigs studied with radioactive blood volume tracers and microspheres of different sizes

In order to further improve the understanding of hemodynamic changes in the immediate postoperative phase after elevation of myocutaneous flaps, regional blood flow and arteriovenous (A-V) shunting were measured in rectus abdominis island flaps in 8 pigs. Radioactive microspheres of two sizes (15 and 50 micron) were used. Approximately half (53.4 +/- 6 percent) of the 15-micron microspheres and one-fourth (24.1 +/- 6 percent) of the 50-micron microspheres entering the flap appeared in the venous outflow. Compared with the control area, A-V shunting was significantly increased in muscle and substantially more pronounced in skin. Nutritional blood flow, total blood flow, and vascular volume were increased in muscle and unchanged in skin and subcutis. The lowest tissue hematocrit of 7 +/- 1 percent was found in skin as compared with a central hematocrit of 35 +/- 2 percent. Tissue hematocrit in flap muscle was decreased to 17 +/- 2 percent when compared with control muscle (22 +/- 3 percent), and the mean transit time for blood was correspondingly decreased. Thus vasodilation provided increased perfusion through muscular capillaries and through A-V shunts. Shunting of 15-micron microspheres appeared to take place not only in skin, but also in subcutis and muscle, which challenges the widespread belief that A-V shunting does not occur in muscle.

Biofeedback Treatment of Children and Adults with Idiopathic Detrusor Instability

In adults and children suffering from urge, urge incontinence, frequent voidings, and nocturia, urodynamic examination often confirms the diagnosis of detrusor instability. We assessed the outcome of biofeedback therapy in 15 children aged 6-12 years and 7 adults aged 20-52 years, all with cystometrically proven detrusor instability. The detrusor pressure was visually conveyed to the patient during repeated bladder fillings. The patient was instructed to interrupt detrusor pressure increments by tensing the pelvic floor musculature. None of the children were found completely cured; however, 9 showed a marked decrease in either the number of the extent of symptoms. Two children showed moderate improvement, while 4 remained unaffected by the treatment. One adult was completely cured, 2 improved moderately, and 4 showed no improvement. None of these patients were converted to stable cystometry. Upon termination of the BF treatment a follow-up study was conducted for patients exhibiting pronounced or moderate improvement. The beneficial effect was maintained except in one case.

The hairless mouse ear: an in vivo model for studying wound neovascularization

Microvascular ingrowth into damaged tissue is an essential component of the normal healing process. In fact, wound therapy is often aimed at promoting neovascularization. However, little is known about the mechanisms that regulate microvascular ingrowth into a healing wound. This limited knowledge is largely due to the lack of adequate models in which microvascular ingrowth can be quantitatively analyzed throughout the healing process. To address this deficiency, we developed a model in which a wound was created on the ear of the hairless mouse—a well established model for directly viewing and measuring skin microcirculation. While the animals were under ketamine and xylazine anesthesia, 2.25 mm diameter full‐thickness wounds were created on the dorsum of hairless mouse ears down to but not including the cartilage (0.125 mm depth). With the use of video microscopy and computer‐assisted digitized planimetry, the precise epithelial and neovascular wound edge was viewed and measured regularly throughout healing. Therefore, this model can provide objective data on wound epithelialization and neovascularization throughout healing. This model was used to examine the effect of topical wound agents on epithelialization and neovascularization. Differential effects by these anti‐microbial agents on these two processes were observed, which suggests clinical implications for their use.

ARTERIOVENOUS SHUNTING AND REGIONAL BLOOD FLOW IN MYOCUTANEOUS ISLAND FLAPS : AN EXPERIMENTAL STUDY IN PIGS

In eight pigs, total blood flow, regional capillary blood flow distribution, and arteriovenous (AV) shunting were studied during the first 4 postoperative hours after elevation of a myocutaneous rectus abdominis island flap. Capillary blood flow and AV shunting were measured using radioactive microspheres before flap creation and 1 and 4 hours after surgery. Total blood flow, measured continuously as venous outflow, increased in the first postoperative hour (p less than 0.05). Elevation of the flap caused a slight decrease in skin capillary blood flow (p less than 0.05), whereas muscular capillary blood flow increased (p less than 0.01). AV shunting accounted for 50 percent of the total flap blood flow, whereas it was negligible in the abdominal wall prior to flap elevation. Thus stalk blood flow, skin appearance, and skin temperature may be poor indicators of nutritional capillary perfusion. However, the clinical and nutritional consequences of these findings remain to be established.

Regional blood flow, plasma volume, and vascular permeability in the spinal cord, the dural sac, and lumbar nerve roots

Objectives This study quantified the regional blood flow (RBF), plasma volume (PV), and the vascular permeability (VP) in the spinal cord, spinal nerve roots, and the dural sac. Summary of Background Data Spinal cord hemodynamics have been investigated. However, the full segmental distribution of blood flow to the spinal cord and nerve roots has not been worked out. Vascular permeability of the spinal cord and nerve roots has been investigated but results regarding the spinal nerve roots have not been consistent. Methods Eight Labrador dogs were used. Regional blood flow was measured with microspheres. Plasma volume and vascular permeability were assessed by the distribution spaces of radiactively labeled plasma proteins. Results Regional blood flow was highest in the cervical and lumbar cord. Average (SEM) RBF values of the cord and spinal nerve roots were 10.4 ± 1.0 and 4.4 ± 0.5 mL/min 100 g, respectively. Plasma volume of the spinal cord was 0.85 ± 0.06 mL/100 g and 1.29 ± 0.17 mL/100 g in the spinal nerve roots. Vessels in the spinal nerve roots had significantly greater permeability to albumin than those of the spinal cord (P < 0.001). Conclusions The quantitative flow measurements showed the existence of three main anatomic territories in the cord. The vascular permeability of vessel in the spinal nerve roots appears greater than that of the spinal cord, indicating that spinal nerve roots are located outside the blood brain barrier. Diffusion might be one of the nutritional pathways to spinal nerve roots.

Ketanserin accelerates wound epithelialization and neovascularization

We investigated the acute effects of topical ketanserin, a 5‐HT2 (serotonin) receptor blocker, on wound epithelialization and vascularization with the use of the hairless mouse ear model. Varying concentrations of Ketanserin (0%, 0.2%, 2.0%, 20% weight/volume) were administered to standardized full‐thickness skin wounds on the dorsum of the hairless mouse ear immediately after surgery and daily thereafter. With the use of video microscopy and computer‐assisted planimetry, vascularization and epithelialization were traced every third day until the wounds were fully healed. Arteriole diameters at selected sites near the skin wound were measured before wound creation and after wounding. It was concluded that topically administered ketanserin significantly accelerates both the vascular (p < 0.001 at 2% and 20% concentrations) and epithelial (p < 0.001 at 20% concentration) rates of wound healing in full‐thickness nonpathologic skin wounds. Vasodilation of terminal arterioles was not a major response to Ketanserin. Faster epithelialization was possibly due to direct effect of ketanserin on epithelial cells.

Technetium 99m diphosphonate uptake and intraosseous hemodynamics during venous congestion in bone

Venous congestion in bone is a common early feature of inflammatory and degenerative joint diseases. An experimental study was performed of the relationship between the scintigraphic appearance of joints and the intraosseous hemodynamics during venous congestion caused by obstruction of the osseous venous drainage by increased intra-articular pressure. Intra-articular pressure was raised to 75% of mean arterial pressure in one knee each of 8 immature dogs. This caused elevated intraosseous pressure in the distal femoral epiphysis but not in the metaphysis. The elevated intraosseous pressure in the affected femoral epiphysis was associated with decreased technetium 99m diphosphonate uptake and blood flow, unaltered vascular volume and tissue hematocrit, and prolonged transit time of blood in the central cancellous bone. The decreased radionuclide uptake during intraosseous venous congestion thus appeared to reflect a decreased blood supply. However, by multiple regression analysis, the diphosphonate uptake in bone generally varied positively with blood flow and plasma volume and inversely with red cell volume in a nonlinear, multifactorial relationship.

Fuel metabolism in a pig myocutaneous island flap model.

Unilateral denervated myocutaneous island flaps based on the superior epigastric vessels were raised in 24 pigs and the metabolic changes during the first 6 postoperative hours were monitored. Secondary to flap elevation, decreased arteriovenous (A-V) differences in oxygen, glucose, and alanine levels were observed, indicating the opening of A-V shunts and increased arterialization of the venous blood. Venous outflow increased during the first 3 hours, but the A-V differences in all metabolites were constant over the entire 6-hour observation period. Exchange of intermediary metabolites therefore increased within the first 3 hours, after which a steady state was established. The main flap fuels seemed to be fatty acids, muscle proteins, and glycogen, whereas blood-borne carbohydrates and ketone bodies played only a minor role as energy sources. Anaerobic metabolism was increased secondary to flap elevation from 2 to 6 percent as compared with preelevation values. No changes were found in concentrations of plasma catecholamines, which were constantly high. An average weight gain of 3 to 4 percent per hour was equally distributed to skin, subcutis, panniculus carnosus, and muscle. Thus the flap seemed to adapt to the new perfusion pattern within a few hours by a slightly increased anaerobic metabolism, but still with an oxidative metabolism of more than 90 percent.