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Biomedical subjects

R B Heppenstall

Publications and source records attributed to R B Heppenstall.

At least 37 records · Page 2Linked to original sources
PubMed1989

Compartment syndrome: a quantitative study of high-energy phosphorus compounds using 31P-magnetic resonance spectroscopy.

The purpose of this study was to quantitate the intracellular high-energy phosphate compounds during 6 hours of tissue ischemia in the anterior tibial compartment of beagles subjected to an induced traumatized compartment syndrome. The goal of this work was to provide clinicians with objective criteria to augment clinical judgment regarding surgical intervention in the impending compartment syndrome. A beagle model was utilized in which the Delta pressure (difference between the mean arterial pressure and compartment pressure) could be controlled. The model, in conjunction with 31P-magnetic resonance spectroscopy (MRS), allowed a measure of high-energy phosphate compounds and pH in the compartment at various Delta pressures. The extent of ischemic metabolic insult in the compartment was then quantitated. Our data suggest the following: 1) lower Delta pressures result in a proportionally greater drop in the intracellular phosphocreatine ratio and pH; 2) at lower Delta pressures, there is proportionally greater decline in the percentage recovery post-fasciotomy; 3) blood pressure is extremely important and periods of hypotension may result in increased muscle damage at lower compartment pressures.

Animals↗
PubMed1988

Treatment of chronic refractory osteomyelitis with adjunctive hyperbaric oxygen.

Twenty-eight consecutive patients with chronic refractory osteomyelitis uncomplicated by persistent segmental bone defect, fracture nonunion, septic arthritis, total joint arthroplasty, or major systemic disease (immune deficiency, malignancy, diabetes mellitus, malnutrition, or renal or hepatic failure) were treated from January, 1980 through December, 1985 to evaluate the potential benefits of hyperbaric oxygen therapy. Patients were classified by a staging system that took into account the bone involved; subchondral, periarticular bone involvement; extent of bone involvement; quality of soft tissue envelope and vascular supply; and general health status of the patient. Using this staging system, patients were assigned to either hyperbaric oxygen therapy or control status after their initial debridement. A regimen of hyperbaric oxygen therapy consisting of 100% oxygen, two atmospheres pressure, two hour duration, one dive per day, six dives per week was used in 14 of the 28 patients. Hyperbaric oxygen had no effect on length of hospitalization, rapidity of wound repair, initial clinical outcome, or recurrence of infection noted to date in this patient population.

Adolescent↗
PubMed1988

The bioenergetics of preservation of limbs before replantation. The rationale for intermediate hypothermia.

Of all tissues of the extremities, muscle is the least tolerant of ischemia. Hypothermia of tissue is considered beneficial for the maintenance of viability of muscle in amputated limbs before surgical replantation, but it has never been established that conventional cooling in an ice bath or its equivalent (temperature of tissue, approximately 1 degree Celsius) is the optimum level of hypothermia for minimizing metabolic derangement in ischemic muscle. In this study, we first defined the time course and level of metabolic derangement of muscle in twenty-eight ischemic hind limbs in cats at 22, 15, 10, 5, and 1 degree Celsius. The levels of adenosine triphosphate and phosphocreatine and the mean intracellular pH of the muscles in the lateral aspect of the thigh in each limb were monitored with phosphorus nuclear magnetic-resonance spectroscopy over time. The excised muscles from six freshly amputated legs of live humans were then similarly studied to determine whether muscles from cats and from humans exhibit comparable bioenergetic responses to hypothermic ischemia. A final series of ten ischemic hind limbs from cats was studied by nuclear magnetic resonance and muscle biopsy for direct biochemical assay of tissue energy metabolites to compare the metabolic benefits of two different methods of preserving limbs: continuous cooling in an ice bath, and a newly devised protocol for the rapid induction and maintenance of so-called intermediate (10 +/- 5 degrees Celsius) hypothermia of tissue. Ischemic skeletal muscle in cats exhibited a paradoxical metabolic response to extreme cold (1 degree Celsius). The rate of metabolic deterioration progressively declined with decreasing temperature of tissue to 10 degrees Celsius. However, at 5 degrees Celsius, no additional benefit was detected, and at 1 degree Celsius, there was a significant acceleration in the rates of degradation of adenosine triphosphate and phosphocreatine and in the production of lactate. The rate of degradation of adenosine triphosphate in human ischemic muscle was also faster at 1 degree Celsius than at 10 degrees Celsius. This paradoxical response is apparently due to a severe inhibition of the calcium pump of the sarcoplasmic reticulum of the muscle cell at temperatures of less than 5 degrees Celsius. The inhibition permits an efflux of calcium to the myofibrils, which stimulates both glycolysis and the degradation of adenosine triphosphate by myofibrillar adenosine triphosphatase.

Adenosine Triphosphate↗
PubMed1988

The compartment syndrome. An experimental and clinical study of muscular energy metabolism using phosphorus nuclear magnetic resonance spectroscopy.

In an experimental ischemic compartment syndrome in dogs, phosphorus (31P) nuclear magnetic resonance (NMR) spectroscopy was used to determine the tissue pressure threshold at which resting skeletal muscle begins to use anaerobic energy sources due to insufficient cellular oxygen delivery. The interactive effects of systemic perfusion pressure and moderate muscle trauma on this anaerobic threshold were also evaluated. The severity of cell injury produced by various degrees of compartment pressurization over an eight-hour period was concomitantly studied using muscle biopsy and electron microscopy. Clinical correlation of a preliminary patient series studied using 31P-NMR demonstrated that the threshold for cellular metabolic derangement in skeletal muscle subjected to increased tissue pressure was more closely associated with the difference between mean arterial blood pressure (MABP) and compartment pressure than with the absolute compartment pressure alone. The difference is termed MABP-compartment pressure, or delta P. The lowest delta P at which a normal cellular metabolic state can be maintained is approximately 30 mmHg in normal muscle and 40 mmHg in moderately traumatized muscle. It is imperative to interpret compartment pressure measurements in light of the degree of soft tissue trauma sustained and the patient's blood pressure, as well as the clinical signs and symptoms.

Animals↗
PubMed1987

Indium-111 leukocyte scintigraphic detection of subclinical osteomyelitis complicating delayed and nonunion long bone fractures: a prospective study.

Twenty patients were studied prospectively with indium-labeled leukocyte imaging to evaluate its effectiveness in differentiating noninfected delayed or nonunion from osteomyelitis complicating these entities. All patients underwent an open surgical procedure within 24 h of the scan. Bone specimens from the nonunion site were obtained for microbiological and histological analysis to confirm the presence or absence of osteomyelitis. In these twenty patients, the sensitivity of the indium scintigraphy was 100%, the specificity 100%, and the overall accuracy 100%. Indium-labeled leukocyte scintigraphy is significantly more accurate than 99mtechnetium and 67gallium imaging had been, when studied earlier, in detecting subclinical osteomyelitis complicating nonunion. Indium-labeled leukocyte scintigraphy should supplant sequential technetium and gallium studies in this patient population when the surgeon must determine whether subclinical osteomyelitis is complicating fracture management of delayed and nonunions.

Adult↗
PubMed1987

Adjunctive hyperbaric oxygen therapy in the treatment of chronic refractory osteomyelitis.

Twenty-eight consecutive patients with chronic refractory osteomyelitis uncomplicated by persistent fracture nonunion, septic arthritis, total joint arthroplasty, or major systemic disease (immune deficiency, malignancy, malnutrition, renal or hepatic failure) were treated from January 1980 through December 1985 to evaluate the potential benefits of hyperbaric oxygen (HBO) therapy. Patients were classified by a staging system taking into account: the bone involved; subchondral, periarticular bone involvement; extent of bone involvement; quality of soft-tissue envelope and vascular supply; and general health status of the patient. Using this staging system patients were assigned to either hyperbaric oxygen therapy or control status after their initial debridement. Hyperbaric oxygen therapy on a 100% oxygen, 2 atmospheres pressure, 2-hour duration, one dive per day, six dives per week regimen was utilized in 14 of the 28 patients. Hyperbaric oxygen had no effect on length of hospitalization, rapidity of wound repair, initial clinical outcome, or recurrence of infection noted to date.

Adolescent↗
PubMed1987

Synovial pseudarthrosis: a clinical, roentgenographic-scintigraphic, and pathologic study.

Seventy-six patients with synovial pseudarthrosis were reviewed. This is a distinct pathologic entity which is a different form of nonunion. The humerus, femur, and tibia were the bones most commonly involved. Routine roentgenograms were not beneficial but 99mTc scans were useful for identifying this entity in 93% of cases. Light and electron microscopy revealed normal synovial lining tissue. Motion and infection may lead to the development of this condition. The results of treatment were a 43% success rate in infected cases and 59% for noninfected cases, which is far different from that of regular nonunion.

Diagnosis, Differential↗
PubMed1987

Supracondylar fracture of the femur following prosthetic knee arthroplasty.

Sixty-one supracondylar fractures above prosthetic knee replacements in 58 patients were reviewed with a mean follow-up time of 3.7 years (range, 9 months to ten years). The mean interim between arthroplasty and fracture was 2.9 years (range, intraoperative to ten years). Twenty-seven cases demonstrated notching of the anterior femoral cortex. Seventeen patients suffered from a severe neurologic disorder. Group A consisted of 30 patients with 31 fractures treated by open reduction and internal fixation or revision arthroplasty. Follow-up study revealed 25 unions, three malunions, one nonunion, and two above-knee amputations for deep sepsis. Four of 31 patients had increased pain levels or change in ambulatory status postoperatively. Group B consisted of 30 fractures in 28 patients treated by casting alone or traction followed by cast bracing. Follow-up examination showed 17 unions, seven malunions, and six nonunions. Fifteen of the 30 patients had increased pain levels or change in ambulatory status after treatment. Casting produced significant decreases in motion in both groups. The results indicate that this fracture is associated with anterior notching of the femoral cortex and preexisting neurologic disorders. Patients with a supracondylar fracture following prosthetic knee arthroplasty are best managed by secure internal fixation and early motion.

Aged↗
PubMed1986

Electrical stimulation of human muscle studied using 31P-nuclear magnetic resonance spectroscopy.

This study used phosphorous nuclear magnetic resonance (31P-NMR) spectroscopy to examine the metabolic demand resulting from electrical muscle stimulation (EMS) applied to human skeletal muscle. For each of six subjects, the forearm flexor muscle group was monitored with 31P-NMR during both maximum voluntary and 6-s EMS-induced contractions. A simple protocol using a tourniquet was added in one subject to assess the role of blood flow in this model. Eight hertz (nontetanic) EMS showed less (p less than 0.025) depletion of phosphocreatine (36%) than did tetanic 70-Hz EMS (60%), voluntary isometric (66%), and voluntary isokinetic (68%). The results of the tourniquet studies suggested that the nontetanic EMS allowed relatively increased muscle blood flow and oxygen supply during contraction. Tetanic EMS provided a similar metabolic demand to that of conventional resistive exercise, as measured by 31P-NMR spectroscopy.

Adult↗
PubMed1986

A comparative study of the tolerance of skeletal muscle to ischemia. Tourniquet application compared with acute compartment syndrome.

In this study, the tolerance of skeletal muscle to tourniquet application (ischemia) and to acute compartment syndrome (ischemia and pressure) was compared. In five animals, the cuff of a pneumatic tourniquet was inflated to 350 millimeters of mercury at the level of the thigh for three hours. In five other animals, an acute experimental compartment syndrome was created in one anterolateral compartment by autologous plasma infusion. The compartment pressure (measured by wick catheter) was maintained at a level equal to the mean arterial pressure for three hours. At three hours, reperfusion was established in both groups, either by tourniquet release or by decompressive fasciotomy and epimysiotomy. During both the ischemic period and a two-hour recovery period immediately thereafter, the mean intracellular pH and high-energy phosphate profile (levels of adenosine triphosphate and phosphocreatine) of the muscles of the anterolateral compartment were monitored non-invasively by phosphorus nuclear magnetic-resonance spectroscopy. Muscle biopsies were done the following day to take specimens for electron microscopic analysis of ultrastructural cellular degeneration. During ischemia, the cellular levels of phosphocreatine decreased at an identical rate in both groups. In contrast, the levels of adenosine triphosphate diminished rapidly in the animals with the compartment syndrome, but remained unchanged in the tourniquet group. Ischemic muscle acidosis was more severe in dogs with the compartment syndrome. In the tourniquet group, the phosphocreatine, adenosine triphosphate, and pH were all normal within fifteen minutes after release of the tourniquet, but these values remained depressed even two hours after fasciotomy in the group with compartment syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1986

Nonunion of the humerus. Clinical, roentgenographic, scintigraphic, and response characteristics to treatment with constant direct current stimulation of osteogenesis.

Forty-six trauma patients who had developed non-union of the humerus were evaluated from 1972 through 1981 as part of a large prospective study on nonunion. The average age of the 46 patients was 55 years. Women outnumbered men (29 women and 17 men). Seventy-one percent of the fractures occurred below the midpoint of the humerus. Inadequate immobilization and/or distraction and failure of internal fixation devices to obtain and maintain fracture fragment contiguity and stability was noted. Of the 46 patients referred, 39 were treated with constant direct current, using percutaneously inserted electrodes. Senile and disuse osteoporosis (62%), synovial pseudarthrosis (42%), obesity (20%), and osteomyelitis (5%) in this older patient population made this a difficult treatment problem. Seventeen patients' nonunions healed (46%). Electrical stimulation of nonunion of the humerus is not a panacea. Patient selection is critical.

Adult↗
PubMed1985

Optimizing tourniquet application and release times in extremity surgery. A biochemical and ultrastructural study.

Despite numerous studies investigating the pathophysiology of tourniquet ischemia, definitive data at the cellular level have been lacking and no consensus regarding safe tourniquet-application times in extremity surgery has emerged. In light of the particular vulnerability of skeletal muscle to ischemic injury, we determined the degree of muscular metabolic derangement and cell damage produced by seven different protocols of tourniquet application and release, each providing three hours of total tourniquet time. We performed thirty-six experiments on canine hind limbs, comparing the following time-patterns of tourniquet application: I--three sequential one-hour periods, II--two sequential one and one-half-hour periods, III--two hours followed by one hour, and IV--a single continuous three-hour application. Five and fifteen-minute reperfusion intervals between ischemic periods were compared for the first three time-patterns, creating a total of seven different tourniquet protocols. Muscular metabolic derangement and cell injury were evaluated by monitoring changes in the cellular bioenergetic state (high-energy phosphate profile), cell pH, post-ischemic leakage of creatine phosphokinase, and ultrastructural cell degeneration. At the intracellular level, the metabolic recovery of muscle during reperfusion was much faster than previous studies focusing on extracellular parameters have indicated. In all instances complete intracellular bioenergetic recovery occurred within five minutes after tourniquet release. The use of one or more five-minute reperfusion intervals significantly reduced the degree of ischemic cell injury, as indicated by a decrease in creatine phosphokinase leakage and myofibrillar destruction. No additional benefit was derived by extending the reperfusion periods to fifteen minutes. The longest period of continuous ischemia in each tourniquet-application protocol bore the closest relationship with the amount of cell damage produced. Within the spectrum of observed pathological changes, time-patterns I and II produced comparatively little muscle damage.

Animals↗
PubMed1984

Prognostic factors in nonunion of the tibia: an evaluation of 185 cases treated with constant direct current.

The present series represents a retrospective clinical study of 185 cases of nonunion of the tibia. The severity of the injury was important in the development of the nonunion. Primary closure of open injuries was noted to be dangerous and resulted in high incidence of infection, 27 of 37 cases. The distal third of the tibia was the most frequent site of the nonunion. One of the most striking findings in this study was a high incidence (92.4%) of patients presenting with initial delay to weight bearing of greater than 6 weeks. The authors feel that this is a definite contributory factor in the development of nonunion of the tibia.

Adult↗
PubMed1984

The infected hip after total hip arthroplasty.

We studied the cases of fifty-two patients with an infection at the site of a prosthetic total hip replacement, and are reporting the significant clinical features, infecting organisms, methods of treatment, and results at long-term follow-up. Forty-eight per cent of the hips had had an operation prior to the index arthroplasty, and 42 per cent had a wound complication. All patients had pain in the infected hip, but only 54 per cent had an erythrocyte sedimentation rate of more than thirty millimeters per hour, 44 per cent had fever, and 15 per cent had leukocytosis. In 88 per cent of the patients a single organism was grown on culture, and Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli were present in about 75 per cent. When antibiotic therapy alone was the initial treatment, the infection was eradicated in only one patient. Excisional arthroplasty was the definitive surgical procedure in thirty-three patients and the infection was eradicated in twenty-seven of them, but the clinical result was satisfactory in only twenty. Of ten patients who had a true Girdlestone arthroplasty, none had recurrence of the infection and all had a clinically satisfactory outcome.

Adult↗
PubMed1984

Muscle ischemia and hypothermia: a bioenergetic study using 31phosphorus nuclear magnetic resonance spectroscopy.

UNLABELLED: Following traumatic limb amputation it is common clinical practice to maintain the ischemic tissues in a hypothermic state until surgical reimplantation. Of all extremity tissues, muscle is the most sensitive to ischemia; it is therefore imperative that reperfusion be established before diffuse muscle necrosis. Although it has been shown both clinically and experimentally that hypothermia prolongs the viability of ischemic skeletal muscle, the presumed mechanism by which this occurs has not been confirmed at the cellular level. This study was undertaken to quantify the effect of conventional iced-saline hypothermia on anaerobic cell metabolism and high-energy phosphate depletion in traumatically devascularized muscle. METHODS: Phosphorus nuclear magnetic resonance spectroscopy (31P NMR) was employed to noninvasively monitor cellular phosphocreatine (PCr), ATP, and intracellular pH over time in ischemic cat hindlimb muscle under room temperature (22 degrees C) and 1 degree C hypothermic conditions. RESULTS: Muscular PCr depletion was significantly retarded by tissue hypothermia but the rate of ATP depletion was not. A progressive, severe cellular acidosis was observed in the room-temperature muscle. Iced tissue cooling produced a dramatic initial rise in cell pH which significantly reduced the absolute degree of subsequent acidotic changes. SIGNIFICANCE: These findings question our understanding of hypothermic tissue preservation, which has generally been assumed to work on the basis of decreased tissue metabolism, thus conserving critical cellular ATP levels. The empirical benefit derived by cooling muscle in an iced medium may actually be related to the cellular alkalinization produced by tissue cooling, as this significantly mitigates the profound acidosis that would otherwise occur.

Adenosine Triphosphate↗