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Biomedical subjects

K S Christensen

Publications and source records attributed to K S Christensen.

At least 19 recordsLinked to original sources
PubMed2005

Recombinant human vascular endothelial growth factor enhances bone healing in an experimental nonunion model.

The re-establishment of vascularity is an early event in fracture healing; upregulation of angiogenesis may therefore promote the formation of bone. We have investigated the capacity of vascular endothelial growth factor (VEGF) to stimulate the formation of bone in an experimental atrophic nonunion model. Three groups of eight rabbits underwent a standard nonunion operation. This was followed by interfragmentary deposition of 100 microg VEGF, carrier alone or autograft. After seven weeks, torsional failure tests and callus size confirmed that VEGF-treated osteotomies had united whereas the carrier-treated osteotomies failed to unite. The biomechanical properties of the groups treated with VEGF and autograft were identical. There was no difference in bone blood flow. We considered that VEGF stimulated the formation of competent bone in an environment deprived of its normal vascularisation and osteoprogenitor cell supply. It could be used to enhance the healing of fractures predisposed to nonunion.

Animals↗
PubMed2000

Ilizarov treatment of tibial nonunions results in 16 cases.

Treatment with the Ilizarov technique was performed in 16 patients with complex tibial nonunions. Two years post treatment the functional stage and patient satisfaction were recorded. There were 4 hypertrophic, 3 atrophic and 9 infected nonunions. Eleven patients had segmental bone loss. Fifteen nonunions united, and limb length discrepancy was reduced within 1.5 cm of the contralateral leg. Average time in the frame was 182 days. Fifteen of the 16 patients were satisfied with the treatment. One patient demanded an amputation after 3 months of treatment, despite good signs of healing. There were no refractures or recurrent infections. In conclusion the Ilizarov technique for complex nonunions has a high rate of success in achieving union and eradicating infection, bone loss and malalignment. The treatment is demanding both to the surgeon and to the patient, but we strongly recommend the Ilizarov treatment for tibial nonunion, especially in cases with chronic infection and severe bone loss.

Adolescent↗
PubMed1995

[Congenital kyphoscoliosis complicated by paraplegia].

Congenital scoliosis accounts for 10% of all scolioses which require treatment. Correct treatment demands an exact and early detection of the deformity. Early intervention may only require a minor operation. Two cases are presented with paraplegia as the first presenting symptom of congenital kyphoscoliosis. In both cases anterior decompression and spondylodesis was followed by early neurological recovery. After a second operation with posterior spondylodesis and instrumentation ad modum Cotrel-Dubousset the patients were mobilised. Patients with congenital spinal deformity ought to be investigated and treated in a highly specialized department of spinal surgery.

Adolescent↗
PubMed1990

Forefoot transcutaneous oxygen tension at different leg positions in patients with peripheral vascular disease.

Transcutaneous oxygen tension (TcPo2) was measured on the forefoot of 150 limbs of 128 patients with different stages of peripheral vascular disease (PVD) and on 36 limbs of 18 healthy subjects in the sitting and supine position. The diagnostic value of TcPo2 measurements was tested and compared with indirect toe pressure measurements. TcPo2 measured in the supine position gives the best diagnostic discrimination between healthy controls and patients with PVD and between patients with different degrees of PVD. The median TcPo2 in patients with PVD and rest pain (severe PVD), patients with PVD without rest pain (moderate PVD) and control subjects was 12 mmHg (range 0-61), 50 mmHg (range 0-86), and 60 mmHg (range 35-78), respectively. In the supine position, 95% of the patients with severe PVD had TcPo2 values below 40 mmHg, as opposed to 28% of the patients with moderate PVD and 8% of the control subjects. TcPo2 below 40 mmHg measured on the forefoot in the supine position suggests severe ischaemia. The diagnostic value of TcPo2 measurement is comparable with that of toe systolic pressure measurement. As a diagnostic and quantitative non-invasive method of evaluating patients suspected of PVD, TcPo2 measurement is ideal as it is easy to perform, and does not cause discomfort.

Adult↗
PubMed1990

Assessment of intermittent claudication by means of the transcutaneous oxygen tension exercise profile.

Transcutaneous oxygen tension was measured simultaneously on both feet during exercise (TcpO2 exercise profile) in patients with claudication. The following groups were studied: 1) 21 control subjects; 2) 25 patients with bilateral claudication of whom eight had unilateral predominance; 3) 40 patients with unilateral claudication. The control group showed no significant decrease in TcpO2 during exercise. Patients with bilateral claudication and unilateral predominance showed a significant decrease in the TcpO2 exercise profile of both feet (P less than 0.05), the decrease in the more affected leg being significantly greater than that of the less affected leg (P less than 0.05). In patients without unilateral predominance of claudication there was a slight, yet significant decrease in TcpO2 of both legs. Patients with unilateral claudication were classified into three groups based on a constant work load of 50 W, which provoked typical leg pain during exercise (group I: 0-2 min; group II: 2-4 min; group III: greater than 4 min). The decrease in the TcpO2 exercise profile was always significant on the symptomatic leg. In the asymptomatic leg TcpO2 did not decrease. The changes in TcpO2 relative to values at rest of the symptomatic leg showed significant differences after 1 min in groups I, II, and III (P less than 0.05). In conclusion, the TcpO2 exercise profile appears to be a suitable objective method by which the peripheral arterial insufficiency during exercise in patients with intermittent claudication can be quantified.

Adult↗
PubMed1990

A model for prediction of failure in amputation of the lower limb.

A logistic regression analysis of eighteen variables in eighty-three lower limb amputations was performed in order to predict stump failure. Five variables were identified as having a significant effect on the logistic model: Age had an inverse relation to failure rate (p less than 0.005). This effect was mediated through a subgroup of 23 patients who had had a vascular operation (p less than 0.02), as this group had a higher failure rate and were younger than those without previous vascular surgery. Furthermore, the surgical experience (p less than 0.005) was of major importance for stump failure. Experienced surgeons had a failure rate of 2% while less experienced had a rate of 29% (p less than 0.001). In addition, it was confirmed that the higher the skin perfusion pressure (p less than 0.05) and the amputation level, (p less than 0.05) the better the healing. A model including "skin perfusion pressure," "previous vascular surgery," "amputation level" and "surgical experience" had a good predictive capability with a misclassification rate of 0.08-0.11. Therefore it is suggested that a logistic model including these variables could be a helpful tool to predict the risk of stump failure.

Adult↗
PubMed1989

[Postoperative analgesia with morphine versus morphine and paracetamol. A double-blind clinically controlled study with a placebo].

The effect of paracetamol on the postoperative employment of morphine was investigated in a double-blind clinically controlled investigation with a placebo. The operations concerned were elective gynaecological laparotomies and hip replacements. During the first 60 hours postoperatively, the employment of morphine was reduced significantly in the patients who received paracetamol. Reductions of 16, 22 and 26% were concerned. The differences between the various types of operation were not significant. Patients for joint replacements who had been treated preoperatively with non-steroid anti-inflammatory preparations did not have any significantly greater consumption of morphine postoperatively but the reduction in consumption of morphine in the paracetamol group was significantly greater with a saving of 43%. Patients who had received treatment with morphine preparations preoperatively had significantly greater consumption of morphine postoperatively but the additive analgesic effect of paracetamol remained unchanged at approximately 25%.

Acetaminophen↗
PubMed1989

The cerebral arterio-venous oxygen content differences (AVDO2) during halothane and neurolept anaesthesia in patients subjected to craniotomy.

In 20 patients subjected to craniotomy for supratentorial cerebral tumours, the haemodynamic changes during halothane and neurolept anaesthesia were evaluated by measuring mean arterial blood pressure (MABP) and cerebral arterio-venous oxygen content differences (AVDO2) repeatedly during the operation. Ten patients were given 0.5% halothane anaesthesia and ten patients neurolept anaesthesia. MABP, AVDO2 and PaCO2 were measured after induction of anaesthesia, before and after incision, after opening and closure of the dura, at the time of extubation and 1 h later. Concerning MABP and PaCO2, no significant difference between the two groups was found. In both groups an increase in MABP was observed after incision (P less than 0.01 in the neurolept group and P less than 0.05 in the halothane group) and in the neurolept group after extubation (P less than 0.01). In both groups a decrease in AVDO2 was observed after incision (P less than 0.01) and after extubation (P less than 0.01 in the neurolept group and P less than 0.05 in the halothane group). During the operation AVDO2 values were significantly higher in the neurolept group (P less than 0.05). The results indicate that even a moderate increase in MABP after incision during neuroanaesthesia affects AVDO2 values, suggesting an increase in cerebral blood flow. The study suggests that autoregulation of cerebral blood flow might be better preserved during neurolept anaesthesia. A state of hyperperfusion of the brain after extubation was unveiled in both groups.

Adult↗
PubMed1989

Long posterior flap versus equal sagittal flaps in below-knee amputation for ischaemia.

We analysed the complication rate in 140 below-knee amputations in relation to surgical technique and the presence of diabetes. In all cases, the skin perfusion pressure was measured below the knee before operation to provide an objective evaluation of the microcirculation. In diabetic patients we found a significantly higher complication rate after using a long posterior flap than after equal sagittal flaps. No such difference could be demonstrated in non-diabetic patients. We suggest that the higher incidence of atherosclerotic lesions in the three major arteries below the knee in diabetic patients may account for the difference. We recommend the use of the sagittal technique for below-knee amputation in diabetic patients.

Amputation, Surgical↗
PubMed1989

Selection of lower limb amputation level not aided by transcutaneous pO2 measurements.

The transcutaneous oxygen pressure measurements were evaluated as supplementary ones for predicting stump healing in 58 below-the-knee and 16 above-the-knee amputations; the lower level was selected if the skin perfusion pressure was greater than 30 mm Hg below the knee. The failure rates in below-the-knee and above-the-knee amputations were 17 and 25 percent, respectively, and unrelated to the transcutaneous oxygen pressure measured at the amputation level. We conclude that no further information is acquired by measuring transcutaneous oxygen pressure.

Amputation, Surgical↗
PubMed1988

Transcutaneous oxygen tension exercise profile. A method for objectively assessing the results after reconstructive peripheral arterial surgery.

Transcutaneous oxygen tension during exercise (TcPo2 exercise profile) was measured on the foot in 10 patients before reconstructive vascular surgery and 9 and 18 months later. The preoperative TcPo2 exercise profiles were abnormal in all 10 patients. In 9 of the patients the reconstructions were successful. In these patients the TcPo2 exercise profiles reverted to normal. In a control group of six healthy persons no significant changes in TcPo2 were observed during the follow-up period of 18 months. The reproducibility determined as the total week-to-week variation of claudicants and controls was 8%. The TcPo2 exercise test is suitable for monitoring the patient after reconstructive surgery, because it is based exclusively on objective data is non-invasive and the measurements are reproducible.

Adult↗
PubMed1988

Results of amputation for gangrene in diabetic and non-diabetic patients. Selection of amputation level using photoelectric measurements of skin-perfusion pressure.

Evaluation was done of 235 patients who had had 273 primary amputations for gangrene. Measurements of local skin-perfusion pressure or systolic blood pressure were made in 222 limbs (188 patients). For the other fifty-one limbs, for which no measurements of pressure were available, the surgeon elected to perform an above-the-knee amputation in nine of seventeen diabetic limbs and a below-the-knee amputation in eight. An above-the-knee amputation was selected by the surgeon for thirty-two of thirty-four non-diabetic limbs and a below-the-knee amputation, for two for which no measurements of pressure were available. Local skin-perfusion pressure was measured distal to the knee before amputation, using a standardized photoelectric technique in 203 limbs and systolic blood-pressure measurements in nineteen. Skin-perfusion pressure was also measured above the knee in seventy-six of the 222 limbs in which a pressure was determined below the knee. These measurements were made available to the surgeon for use as an adjuvant guide to clinical assessment in selecting the appropriate level of amputation. Seventy-four patients (ninety-two amputations) had diabetes and 114 patients (130 amputations) did not. The limbs of the diabetic patients had a significantly higher skin-perfusion pressure at the below-the-knee level (p less than 0.001) than did those of the non-diabetic patients. The ratios of below-the-knee to above-the-knee amputations for the diabetic and non-diabetic patients were 3.8 to one and 1.3 to one (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗