Isolated hindlimb perfusion in dogs: the effect of perfusion pressures on the oxygen supply (ptO2 histogram) to the skeletal muscle.

During regional isolated perfusion, neoplasms in extremities are treated with high doses of chemotherapeutic drugs by means of an extracorporeal circuit. The question is whether optimal tissue perfusion, which is essential for the therapy, is obtained by regulation of the extracorporeal circuit on an adequate perfusion flow or on an adequate perfusion pressure. To determine which perfusion pressure is needed to maintain adequate tissue perfusion, hindlimbs of six dogs were perfused at perfusion pressures 0, 15, 25, and 50 mm Hg below systemic mean arterial pressure. A multiwire polarographic oxygen electrode placed on the sartorius muscle permitted quantitative evaluation of tissue oxygenation by means of ptO2 histograms. Our results indicated that the perfusion pressure must be equal to or within 15 mm Hg below systemic mean arterial pressure to obtain optimal tissue perfusion. To maintain this perfusion pressure, high perfusion flows of about five to 10 times control femoral flows were needed. At a perfusion pressure 50 mm Hg below systemic mean arterial pressure, perfusion flow was normal, but tissue perfusion was severely impaired.

Spontaneous remodeling of the spinal canal after conservative management of thoracolumbar burst fractures.

STUDY DESIGN: Forty-two conservatively treated patients with a burst fracture of the thoracic, thoracolumbar, or lumbar spine with more than 25% stenosis of the spinal canal were reviewed more than 1 year after injury to investigate spontaneous remodeling of the spinal canal. OBJECTIVES: To investigate the natural development of the changes in the spinal canal after thoracolumbar burst fractures. SUMMARY OF THE BACKGROUND DATA: Surgical removal of bony fragments from the spinal canal may restore the shape of the spinal canal after burst fractures. However, it was reported that restoration of the spinal canal does not affect the extent of neurologic recovery. METHODS: Using computerized tomography, the authors compared the least sagittal diameter of the spinal canal at the time of injury with the least sagittal diameter at the follow-up examination. RESULTS: Remodeling and reconstitution of the spinal canal takes place within the first 12 months after injury. The mean percentage of the sagittal diameter of the spinal canal was 50% of the normal diameter (50% stenosis) at the time of the fracture and 75% of the normal diameter (25% stenosis) at the follow-up examination. The correlation was positive between the increase in the sagittal diameter of the spinal canal and the initial percentage stenosis. There was a negative correlation between the increase in the sagittal diameter of the spinal canal and age at time of injury. Remodeling of the spinal canal was not influenced by the presence of a neurologic deficit. CONCLUSION: Conservative management of thoracolumbar burst fractures is followed by a marked degree of spontaneous redevelopment of the deformed spinal canal. Therefore, this study provides a new argument in favor of the conservative management of thoracolumbar burst fractures.

Prevention of fracture at the distal locking site of the gamma nail. A biomechanical study.

To investigate the origin of fractures at the distal locking site of the Gamma nail, we loaded ten paired human cadaver femora fixed with a Gamma nail in torsion until they fractured. When an awl was hammered in to start the hole for distal locking a fissure appeared in the lateral cortex of all the femora, and the mean torsional load to create a fracture was reduced by 57.8% compared with that in a control group in which the distal locking hole had been started with a centre drill. When an additional drill hole was made, the mean failure load in torsion decreased by 35.7%. We strongly recommend that an awl should not be used at the distal locking site of the Gamma nail; we recommend the use of a centre drill. Additional drill holes should be avoided because they act as stress raisers.

CT scan prediction of neurological deficit in thoracolumbar burst fractures.

In 139 patients with burst fractures of the thoracic, thoracolumbar or lumbar spine, the least sagittal diameter of the spinal canal at the level of injury was measured by computerised tomography. By multiple logistic regression we investigated the joint correlation of the level of the burst fracture and the percentage of spinal canal stenosis with the probability of an associated neurological deficit. There was a very significant correlation between neurological deficit and the percentage of spinal canal stenosis; the higher the level of injury the greater was the probability. The severity of neurological deficit could not be predicted.

Motor cycle injuries in speed sport for youngsters.

In speedsport motorcycling for youngsters (6-16 years) is gaining an increasing popularity. We had the impression that there was an increase in the number of injured young motorcyclists. Therefore we studied the kind, cause and severity of the injuries sustained to 32 young motorcyclists treated in the Department of Traumatology of the University Hospital Groningen. This group consisted of 31 boys and one girl, aged 7 to 16, with an average age of 13.3. The severity of the injuries varied from sprain and strain of joints to compound bone fractures and twice a rupture of the liver. 29% of all patients were treated as in patients. Our conclusion from this study is that there was a considerable increase in number of injured young motorcyclists as well as in severity of the injuries. In this study we discuss some suggestions for accident prevention.

Rushpin fixation for midshaft clavicular nonunions: good results in 13/14 cases.

We treated 14 patients having a symptomatic mid-shaft clavicular nonunion with intramedullary Rushpin fixation and autogenous bone grafting. 13 nonunions healed within 4 months. There were no complications related to the operation. After a mean follow-up of 40 (4-156) months, shoulder function (Constant-Murley score) was 90 (44-100)%, compared to the contralateral shoulder. Rushpin fixation with autogenous bone grafting is a simple and reliable method for treating nonunions of the midshaft of the clavicle.

Effects of acute bleeding on oxygen supply to the skeletal muscle in dogs.

To study the effect of acute bleeding on the oxygen supply to the skeletal muscle, heparinized dogs were bled via an arterial cannula until mean arterial pressures of 25 and 50 mm Hg below initial value were reached. The shed blood was retransfused in reverse (50, 25 mm Hg) after correction of the acid-base imbalance in the dogs. Oxygen supply to the skeletal muscle was measured by means of a multiwire polarographic electrode placed on the sartorius muscle and was evaluated by means of ptO2 histograms. The ptO2 histograms showed that the oxygen supply to the skeletal muscle is severely impaired after a decrease in mean arterial pressure of 25 mm Hg. Further impairment was seen after a decrease in pressure of 50 mm Hg. During retransfusion tissue oxygenation was normalized only after all shed blood was retransfused and the initial mean arterial pressure was reached.

Neurological deficit in injuries of the thoracic and lumbar spine. A consecutive series of 70 patients.

Seventy consecutive patients with injuries of the thoracic and lumbar spine accompanied by neurological deficit were prospectively studied and follow-up. In 40 of these patients with a burst fracture, the degree of involvement of the cross-sectional area of the spinal canal, as revealed on first CT after admission, was not correlated with the type and degree of initial neurological deficit. In patients with injuries of the lumbar spine, neurological deficit may be mild, although the sagittal diameter of the spinal canal may be reduced by as much as 90%. We cannot establish a difference in neurological recovery between those cases who were managed conservatively and those in whom a surgical decompression and stabilization procedure was performed. Surgical stabilizing procedures, however, result in immediate stabilization of the spine, they diminish pain, facilitate nursing care and allow more rapid mobilization and earlier active rehabilitation. If major extraspinal injuries form a relative contra-indication to surgical decompression of the cord and stabilization of the spine injury, the patient can quite well be treated conservatively without endangering neurological recovery.

Improved tissue perfusion during pressure regulated hyperthermic regional isolated perfusion. A clinical study.

In previous studies on isolated hindlimb perfusions in dogs, the authors proved that the extracorporeal circuit should be regulated at a delta pressure (systemic mean arterial pressure minus hindlimb mean arterial pressure) of not more than 15 mmHg, to achieve adequate tissue perfusion. To confirm this in patients the authors performed clinical perfusions, divided into three groups. In group I and II the extracorporeal circuit was regulated at a delta pressure of 15 mmHg and 50 mmHg, respectively. In group III perfusions were performed using the common technique of a predetermined fixed flow. Tissue oxygenation, determined by means of a transcutaneous pO2 electrode, was adequate in group I and was severely impaired in group II and III. Although in group I high perfusion flows were needed, leakage was less than 10%. To achieve adequate tissue perfusion during clinical regional perfusions, the extracorporeal circuit must be regulated at a delta pressure of 15 mmHg.

Improved tissue perfusion during pressure-regulated hyperthermic regional isolated perfusion in dogs.

To achieve adequate tissue perfusion during regional isolated perfusion, hind limbs of dogs were perfused for 60 min, regulating the extracorporeal circuit on pressure. The dogs were divided into three groups. In groups I and II perfusions were performed at a delta pressure (systemic mean arterial pressure minus hind limb mean arterial pressure) of respectively 50 and 15 mm Hg; in group III delta pressure was also 15 mm Hg but the cytostatic drug Melphalan was added. Tissue perfusion was determined by means of a multiwire polarographic oxygen electrode. Adequate tissue perfusion was obtained only at subnormal perfusion pressures (groups II and III), although in all groups perfusion flow was higher than preoperative flow. At low perfusion pressures (group I), tissue perfusion was severely impaired. In all groups leakage remained less than 10%. During regional isolated perfusion the extracorporeal circuit must be regulated at a delta pressure of 15 mm Hg to achieve adequate tissue perfusion.