Biomedical subjects

V E Hjortdal

Publications and source records attributed to V E Hjortdal.

63 records · Page 4Linked to original sources

PubMed1991

Tissue oxygen tension in myocutaneous flaps. Correlation with blood flow and blood gases.

The relationship between tissue oxygen tension (PO2) and blood flow, blood gas tensions, oxygen delivery, and oxygen consumption was investigated in myocutaneous island flaps in 24 pigs. The tissue PO2 was measured by the silicone rubber tonometer technique. Capillary blood flow was increased during the first 3-4 hours after implantation of tonometers and they must, therefore, be implanted 3-4 hours before use. After raising the flap, mean (SEM) total flap blood flow increased from 11.2 (0.8) ml/min to 16.0 (1.3) ml/min within the first three hours. Mean (SEM) subcutaneous tissue PO2 decreased from 9.5 (0.6) kPa to 5.2 (0.7) kPa over six hours after the procedure, whereas muscle PO2, blood oxygen tension, and arteriovenous oxygen difference were unchanged. Hence, both the supply to, and use of oxygen in, the flap increased. Muscular and subcutaneous oxygen tensions were about 3 and 1 kPa, respectively, lower than venous oxygen tension. Tissue PO2 did not correlate with blood flow, blood oxygen tensions, arteriovenous differences in oxygen tension, or with oxygen supply in a cross section of animals. Tissue PO2 seems to reflect accurately the balance between oxygen supply and consumption, which might be the most useful indicator for continuous flap monitoring.

Animals↗

PubMed1991

Continuous direct tissue oxygen tension measurement. A new application for an intravascular oxygen sensor.

An oxygen tension measurement equipment, developed for continuous intravascular monitoring was tested as a direct tissue oxygen tension meter. The sterile disposable oxygen probe consists of a Clark type polaro-graphic bipolar electrode placed in a 5 cm long flexible polyethylene catheter (OD 0.55 mm). The probe is easily placed, e.g. in subcutaneous tissue or muscle, with the aid of an introduction needle. In vitro measurements as well as subcutaneous and intramuscular readings were performed. The animals were subjected to various experimental conditions such as different inspiratory oxygen fractions, hypovolemia, and circulatory impairment. Results were comparable to those obtained with previously used and well characterized tissue oxygen tension measurement equipment. The clinical applicability of the oxygen sensor for tissue oxygen measurement was assessed in one patient by 40 hours' surveillance in a free myocutaneous flap. The procedure was simple and implied minimal discomfort for the patient.

Animals↗

PubMed1990

[Conjunctival oxygen tension. Testing oxygen tension measurement of the conjunctiva].

A new apparatus which can measure oxygen tension and temperature in the conjunctiva was tested and compared with measurements of transcutaneous and arterial oxygen tension in eight volunteers in connection with normal oxygen tension, hypoxia and hyperoxia. In hypoxia, the conjunctival oxygen tension was found to be better correlated to and in better agreement with arterial oxygen tension than transcutaneous oxygen tension. The advantages with conjunctival oxygen measurements are continuous measurements in easily accessible and well vascularized tissue with the same arterial supply as the brain. In contrast to transcutaneous measurement, the new method does not require warming of the tissue as the conjunctiva is oxygen permeable.

Blood Gas Analysis↗

PubMed1990

The influence of tissue tension on the microcirculation in myocutaneous flaps: an experimental study in dogs.

The effect of increased and decreased uniaxial tissue tension on capillary blood flow, plasma volume, edema formation, and vascular permeability in myocutaneous flaps was studied. A total of 64 equally sized arterialized myocutaneous flaps were outlined on the abdomen of 16 dogs. The four areas on each dog were randomized to either untouched control area, reattachment to normal tension, increased (one and one-half times the original length), or decreased (one-half times the original length). Capillary blood flow measured by the radioactive microsphere technique two hours after operation was decreased in the muscular part of flaps reattached at decreased and normal tension (p less than 0.05). The muscular blood flow was unchanged when flaps were reattached at increased tension and significantly higher than in flaps reattached at decreased tension (p less than 0.05). No differences were found in skin or subcutaneous blood flow. There were no differences in plasma volume, vascular permeability, or total water content between flaps attached under different tensions, whereas the plasma volume was increased in muscle in all three flap types (p less than 0.05) presumably secondary to venous stasis. The study implies that the decreased capillary blood flow seen in the muscular component of a myocutaneous flap in the immediate postoperative period may be counteracted by a somewhat increased reattachment tension.

Abdominal Muscles↗

PubMed1990

Tissue oxygen tension measurement for monitoring musculocutaneous and cutaneous flaps.

In pigs, latissimus dorsi musculocutaneous island flaps and buttock skin island flaps were raised. Subcutaneous (PscO2) and intramuscular oxygen tension (PimO2) were measured using a non-heated needle electrode before, during and after repeated occlusion of the supplying artery or the draining vein. During arterial and venous occlusion, the tissue oxygen tension in the musculocutaneous flap dropped rapidly. A plateau was reached after 15 min. After arterial occlusion the mean value was 20 mmHg (SEM = +/- 5 mmHg, N = 6) in the subcutis and 16 mmHg in the muscle (SEM = +/- 4 mmHg, N = 10). After venous occlusion the mean value was 11 mmHg (SEM = +/- 3 mmHg, N = 6) in the subcutis. In the skin flap the drop of PscO2 was slower, and after 30 min of arterial occlusion the mean value was 29 mmHg (SEM = +/- 9 mmHg, N = 6). This study has shown that tissue oxygen tension measurement can be used as a sensitive indicator of acute impairment of the supplying vessels in island flaps. The method seems to have potential for monitoring free tissue transfers. A comparable decrease in PscO2 was found for arterial and venous impairment.

Animals↗

PubMed1990

Synovitis reduced by inhibition of leukotriene B4. Carrageenan-induced gonarthritis studied in dogs.

The pathophysiologic significance of leukotriene B4 (LTB4) in arthritis was studied in dogs by unilateral intraarticular deposition of 15-hydroxy-eicosatetraenoic acid (15-HETE), an endogenous inhibitor of the formation and the effects of LTB4, in bilateral carrageenan-induced gonarthritis. LTB4 in synovial fluid was selectively inhibited in 15-HETE treated joints, the formation of prostaglandin E2 (PGE2) being largely unaffected. The clinical symptoms, intraarticular pressure, and extractable synovial fluid volume were reduced in treated joints. No effect could be discerned regarding blood flow in the synovial membrane, capsule, or juxta-articular bone as measured by tracer microspheres; and no effect on bone metabolism was found as judged by 99mTc-diphosphonate uptake. Thus, inhibition of LTB4 reduces joint exudation, but does not seem to interfere with changes in juxta-articular hemodynamics or bone metabolism following synovial inflammation.

Animals↗

PubMed1989

[Dihydroergotamine and orthostatic hypotension in elective hip surgery].

The authors undertook a prospective double-blind, controlled trial to investigate the effect of prophylactic low-dose heparin/dihydroergotamine, low-molecular heparin/dihydroergotamine and a placebo on the blood pressure and postural hypotension on postoperative mobilization. A material of 120 patients admitted for hip surgery was subdivided at random into three groups. Examination for postural hypotension was undertaken on the fifth postoperative day. No significant differences were present between the three groups as regards age distribution, systolic and diastolic blood pressures and pulse rates. This investigation did not reveal any significant effect of the antithrombotic combined treatment with heparin/dihydroergotamine on the blood pressure or postural hypotension on postoperative mobilization following elective hip surgery. No cases of ischaemic side effects were observed. However, this investigation cannot disprove a slight hypotensive effect and, for this reason, this treatment should be contraindicated in patients with circulatory disturbances.

Aged↗

PubMed1989

Three-phase [99mTc]diphosphonate scintimetry in septic and nonseptic arthritis of the immature knee: an experimental investigation in dogs.

We compared the informative value of dynamic and static [99mTc]diphosphonate ([99mTc]DPD) scintimetry in early septic arthritis (SA) and chronic nonseptic arthritis (NSA) of the knee in puppies. SA (n = 10), induced by injection of Staphylococcus aureus into one knee, was examined after 48 h. NSA (n = 6) was induced by weekly intraarticular instillation of 1% carrageenan and examined at 2 and 12 weeks. Epiphyseal and metaphyseal count ratios (CRs) between experimental and control joint were calculated in an angiographic phase (0-20 s), a "blood pool" phase (20-256 s), and a bone uptake phase (2 hs). Control dogs (n = 4) had a CR of 1.0 in all regions and phases, the coefficients of variation being 0.06 and 0.03 in dynamic and static phases, respectively. In NSA, all scintimetric phases showed decreased metaphyseal uptake and largely unchanged epiphyseal uptake. Generally, SA exhibited vastly increased angiographic uptake in all regions and increased epiphyseal blood pool uptake, whereas delayed epiphyseal uptake varied and delayed metaphyseal uptake tended to decrease. Two septic joints had generalized reduction in dynamic uptake, probably owing to increased intraarticular pressure; in one of these, dynamic uptake in the distal femoral epiphysis (FE) was totally absent, suggesting temporary circulatory arrest during the dynamic scanning procedure. The use of regional dynamic and static [99mTc]DPD scintimetry increased the pathophysiologic and diagnostic value of joint scintigraphy, especially with respect to the early detection of SA and its avascular complications.

Animals↗

PubMed1989

99mTc-DPD uptake in juvenile hemarthrosis. Scintimetry and autoradiography of the knee in dogs.

The pathogenesis of subchondral bone lesions and growth plate affection in hemophilic arthropathy was studied in puppies by means of repeated regional 99mTc-diphosphonate scintimetry and contact autoradiography. Unilateral hemarthrosis of the knee was induced by biweekly intraarticular injections of autologous blood for 12 weeks. Hemarthrosis caused an early (2 to 4 weeks) decrease in uptake of 99mTc-diphosphonate in the juxtaarticular growth plates (ratio 0.7) and a delayed (8 to 10 weeks) increase in epiphyseal uptake (ratio 1.5). In a recovery phase after hemarthrosis, growth plate uptake returned to normal, while the epiphyseal uptake remained elevated for 8 to 10 weeks. By contact autoradiography, the growth plate uptake was localized to the calcification layer at the metaphyseal aspect of the growth plates, while the epiphyseal uptake mainly was seen in the thin subchondral and subsynovial bone layer and around osteophytes. The changes in uptake of 99mTc-diphosphonate following hemarthrosis for 3 months were reversible and could be ascribed to the presence of synovial inflammation.

Animals↗