PubMed HealthSearch

Biomedical subjects

G T Rodeheaver

Publications and source records attributed to G T Rodeheaver.

At least 19 recordsLinked to original sources

Biomechanical performance of ophthalmic surgical needles.

The mechanical performance of ophthalmic surgical needles is studied. Standard biomechanical tests, devised to evaluate the performance of ophthalmic surgical needles, are presented. Four comparable groups of ophthalmic surgical needles were selected from two different manufacturers for these biomechanical studies. The results of this testing demonstrate that needle point geometry and needle composition are important determinants of needle performance. When comparable size needles were evaluated, the biomechanical performance of the recently introduced CS160-6 ophthalmic needle (Ethicon, Inc) was superior to the AU-5, CU-5, and SU-5 needles (Alcon, Inc). Whereas the development of these biomechanical tests has allowed the evaluation of these ophthalmic needles, these same tests can be used to assess the performance of other new ophthalmic surgical needles.

Alloys

Early tissue reaction to textured breast implant surfaces.

Capsular contracture around breast implants with smooth surfaces continues to be an unpredictable complication. Some surgeons believe that silicone implants covered with porous polyurethane foam have a lowered potential to contract. These textured implants are not as biocompatible as silicone. Recently, silicone implants with textured surfaces have been introduced with the hope that the incidence of unacceptable implant contracture will be reduced. Using a rat implant model, the tissue reaction to textured implant surfaces was assessed. The implant surfaces evaluated were Silastic II, Siltex, MISTI, Biocell, Silastic MSI, and Même. Disks of each implant material were implanted under the dorsal skin of rats for a period of 28 days. Each implant with its surrounding tissue was excised, processed for histological analysis, and assessed for the tissue's response to the implant with particular emphasis on the formation of a continuous collagen capsule. The results indicated that the magnitude of surface texturing influenced the development of a complete capsule. Implant surfaces with a texture of less than 150 microns in height or depth (Silastic II, Siltex, and MISTI) resulted in the formation of complete capsules. An implant (Biocell) with irregular texturing (200-350 microns) produced an organized capsule over most of its surface with localized interruptions of the capsule at the sites of its deepest cavities. Implant surfaces with texturing that exceeded 350 microns in height or depth (Silastic MSI and Même) resulted in inhibition of the formation of a continuous capsule during this 28-day study.

Adipose Tissue

Activity of antibiotics in contaminated wounds containing clay soil.

Most traumatic wounds are contaminated to some degree by soil and run a high risk of infection. The presence of soil in wounds interferes with natural tissue defenses, which include phagocytosis and serum bactericidal capacity. The experimental studies reported herein clearly demonstrate that soil also limits the antibacterial effects of specific antibiotics. This inactivation appears to be the result of a chemical reaction between the charged antibiotics and the soil particles.

Animals

Extinguishing the flaming burn victim.

The multipurpose dry chemical fire extinguishers are unusually efficient in extinguishing many classes of fire: A) ordinary combustible; B) flammable liquids and C) electrical equipment. This exemplary performance of multipurpose extinguishers is associated with minimal toxic effects to humans. Following contact of soft tissue with the multipurpose dry chemical, the tissue exhibits a remarkable ability to resist infection and a normal capacity to heal following injury. This negligible toxicity of the multipurpose dry chemicals makes them safe for extinguishing the flaming clothes of human burn victims.

Animals

Practical technique for quantitating anaerobic bacteria in tissue specimens.

Quantitative bacteriology has considerable influence on the care and management of surgical wounds. Heretofore, these techniques have been limited to measurements of aerobic bacteria. A technique is reported herein which permits quantitation of obligately anaerobic bacteria in tissue specimens. This technique is easily reproduced in any clinical laboratory and eliminates the need for expensive anaerobic chambers.

Anaerobiosis

Craniofacial growth following experimental craniosynostosis and craniectomy in rabbits.

Premature fusion of the coronal suture was produced in 9-day-old rabbits by immobilization of the suture area bilaterally with methyl-cyanoacrylate adhesive. The effects of suture fusion and its surgical release on suture growth and on skull morphology were evaluated by radiographic cephalometry. Immobilization resulted in significant changes in the angular dimensions in the vault toward an anteroposterior shortening. No permanent deformity was observed in the angular relationship between the cranial base and the facial skeleton. Craniectomy at 30 days, when a skull deformity had been established, resulted in rapid separation of the bones at the suture site which returned the deformed skull to a normal configuration by 90 days of age. Surgical removal of a normal suture in a control group also resulted in accelerated separation of the bones at the excised suture site, but it was less than after removal of an immobilized suture. The experimental data indicate that premature fusion of rapidly growing sutures results in consistent skull deformity. Early release of the fusion, when this is the primary abnormality, will result in spontaneous correction of the deformity.

Age Factors

Mechanisms by which proteolytic enzymes prolong the golden period of antibiotic action.

These experimental studies provide an explanation for the therapeutic value of proteolytic enzymes as adjuncts to antibiotic treatment of contaminated wounds. After wounding, a fibrinous coagulum develops on the wound surface. This coagulum surrounds the bacteria and protects them from contact with sustemically or topically administered antibiotics. Treatment of the wound surface with proteolytic enzymes disrupts the coagulum and exposes the bacteria to the action of the antibiotic. The topical use of enzymes is also associated with significant increases in the concentration of antibiotic at the wound and thus a decrease in the rate of infection.

Administration, Topical

Airless paint gun injuries: an update.

The airless paint gun delivers paint at pressures approximating 3,000 psi. Paint accidently injected into the skin under this pressure causes a devastating injury which is a result of the paint material, the level of bacterial contamination, and the pressure at which the paint is delivered. The time interval between injury and treatment seems a critical determinant of outcome. Decompression of the closed vascular compartments of the hand must be begun immediately to release the underlying tissue distended by the injected paint. Judicious wound debridement must be performed. Immediate antibiotic treatment is indicated in all patients. Studies seem to indicate that steroids limit the severity of inflammatory response. A regimen of hydrocortisone sodium succinate, 100 mg IV, administered immediately before surgery should be followed by a seven-day tapering course of oral prednisone starting with 40 mg on the first postoperative day. Recent safety measures and consumer warnings through the Consumer Product Safety Commission may reduce the number of airless paint gun injuries.

Adrenal Cortex Hormones

Modification of the American Burn Association injury severity grading system.

This study evaluated the regional burn health care system of the Commonwealth of Virginia using the criteria for optimal care of the burn patient designated by the American Burn Association. The data base for this evaluation was hospital records of seven hospitals in Virginia. The major shortcoming of the designated criteria was the grading system for the severity of burn injury. Using the criteria designated by the American Burn Association, a large number of minor burn injuries were judged erroneously to be major burn injuries. A modification of the American Burn Association's injury severity grading system is proposed which more precisely identifies the minor burn injury.

Aged

Rapid antibiotic disk sensitivities of burn eschar and infected wounds.

This study was undertaken to develop a more rapid antibiotic sensitivity test of the pathogens in soft tissue infections and burn wound eschar. The proposed rapid antibiotic sensitivity test was performed directly on the clinical specimen rather than on single strains of bacteria isolated from the tissue. By performing the antibiotic sensitivity tests directly on the tissue sample, the physician obtains the test results within seven hours after receiving the specimen rather than 38 to 52 hours later, the time delay encountered with the conventional technique. The modification used did not alter most of the standards advised by the Food and Drug Administration (3), since there was no inclusive change in medium, agar depth or antibiotic sensitivity disk. The changes in the Kirby-Bauer (1) test necessitated by using the clinical specimen did not alter significantly the interpretation of the antibiotic susceptibility. If clinically significant numbers of bacteria, 10(6)-10(9), were present, variations in the inoculum size did not appreciably change the results of the antibiotic susceptibility tests. If the incubation requirement for the standard Kirby-Bauer (1) antibiotic susceptibility test was reduced to seven hours, it also did not significantly limit the accuracy of the test. As expected, the variable most difficult to standardize was the heterogeneous inoculum containing large numbers, 10(7), of different organisms. A zone of inhibition interpreted as sensitive with one organism was occasionally masked by the presence of the confluent growth of an organism in which the zone of inhibition was considered resistant. However, even in this instance, it is possible that mixed culture sensitivities may provide the most valid information in mixed infections, since they more closely simulate the real clinical situation.

Anti-Bacterial Agents

Management of soft tissue injury.

The fate of a surgical wound is held in a delicate balance between the host's resistance to infection and the causal factors of infection. Considerable insight into this relationship between the host and pathogen can be gained from the results of quantitative bacteriologic measurements. Newer rapid slide techniques have been developed which provide the surgeon with this information within 20 minutes. In most soft tissue injuries, the wound bacterial count gives an accurate prediction of subsequent infection. Wounds combining greater than 10(5) bacteria per gram of tissue are destined to develop infection. When the bacterial count is below that level, the wounds will usually heal per primam without infection. This large number of bacteria required to elicit infection reflects the remarkable ability of soft tissues to resist infection. This state of high resistance to infection can be reduced by several factors which include circulatory embarrassment, tissue injury, dead space, and the presence of foreign bodies (dirt, sutures, drains, etc.). When treating soft tissue injuries, the surgeon must employ specific therapeutic modalities that allow the wound to heal per primam without infection. On the basis of experimental studies supported by clinical experience, the following treatment protocol for soft tissue injuries is recommended. Using strict aseptic technique, the wound must be first anesthetized with 1 per cent Xylocaine to permit painless sound cleansing. All wounds should be subjected to high pressure syringe irrigation to remove bacteria, foreign bodies, and blood clots. When necessary, debridement of all devitalized tissue should be performed with a stainless steel scalpel. Many wounds caused by sharp wounding agents contain no foreign bodies and few bacteria and exhibit considerable resistance to infection. In these wounds, primary closure can be initiated after irrigation without the development of infection. Wounds resulting from impact forces have a diminished resistance to infection and are susceptible to infection by low level of bacterial contamination. Immediate antibiotic treatment of patients with impact injuries subjected to meticulous debridement and cleansing will permit a safe primary closure. In wounds contacted by pus or feces, open wound management followed by delayed primary closure is usually indicated. Antimicrobial prophylaxis is also recommended for patients with such wounds. Ideal postoperative care of all traumatic wounds includes a surgical dressing and immobilization and elevation of the site of injury.

Anesthesia, Local

Practical bacteriologic monitoring of the burn victim.

A comprehensive picture of the burn wound microflora is now possible as a result of recent technologic advances. The microflora of the burn wound can be characterized with respect to its number, type, location, and antibiotic sensitivity. These parameters can be measured in sufficient time to influence the decision of the burn surgeon. The microflora of the surface of the burn wound and the burn wound itself are examined separately by different sampling techniques. For the surface microflora, the gauze capillary techniques employed, while incisional biopsies are used to monitor the organisms in the burn wound. After sampling, suspensions of the specimens are created which in turn are subjected to direct microscopic measurement, quantitative culture procedures, and immediate antibiotic sensitivity testing. Histologic examination of the burn wound is performed concomitantly with this bacteriologic examination to determine the depth of bacterial invasion as well as to detect the presence of either mycotic or herpetic infections.

Animals

Inhibition of nonspecific defenses by soil infection potentiating factors.

This study was undertaken to examine the effect of soil infection potentiating factors on the defense system of the tissue. Using an in vitro model, leukocyte phite. This damaging effect on leukocyte function was a result of an interaction between the leukocyte and the clay particles. Montmorillonite also interfered with nonspecific humoral defenses. Exposure of serum to clay rapidly eliminated its bactericidal bodies occurred without any damage to the serum opsonins.

Bacteria

The role of implant porosity on the development of infection.

The role of implant porosity as a determinant of infection was studied. Standardized porous and nonporous polymethyl methacrylate implants were fabricated for this investigation. In rabbits, the premolded polymethyl methacrylate implants were placed under the paravertebral fascia, just superficial to the paravertebral muscle fascia, before inoculation with a measured number of staphylococci. The polymethyl methacrylate implants did not enhance the infection rate of the contaminated wounds. The presence of pores within the implants did not damage tissue defenses. Polymethyl methacrylate implants did not alter the success of antibiotic treatment. Antibiotics prevented the development of infection in wounds containing 10(6) organisms, even in the presence of an implant. When higher levels of organisms were delivered to the wound, antibiotic treatment had a negligible benefit in the implant and control wounds.

Animals