John O. Kucan

Morphologic analysis of the microcirculation during reperfusion of ischemic skeletal muscle and the effect of hyperbaric oxygen.

The morphologic events in the microcirculation that lead to reperfusion injury of ischemic skeletal muscle remain incompletely understood. The purpose of this experiment was to evaluate leukocyte endothelial adherence characteristics and dynamic changes in microvessel caliber during reperfusion of an in vivo skeletal muscle ischemia preparation. In addition, the effect of hyperbaric oxygen treatment on these microcirculatory changes also was studied. An intravital microscopy preparation of a transilluminated gracilis muscle in 27 rats was used to observe a total of 101 arterioles and 63 venules (13 to 73 μm diameter). Baseline hemodynamics were videotaped for 30 minutes following muscle isolation. The animals were divided into six groups: (1) sham, no ischemia, (2) 4 hours of global ischemia only, (3) no ischemia plus hyperbaric oxygen (one 2.5 ATA/1 hour of treatment with 100% oxygen), (4) 4 hours of ischemia plus hyperbaric oxygen during ischemia, (5) 4 hours of ischemia plus hyperbaric oxygen immediately on reperfusion, and (6) 4 hours of ischemia plus hyperbaric oxygen 1 hour after reperfusion. Changes in arteriolar and venular diameters at specific times during 3 hours of reperfusion were recorded, and the number of adherent and slow-rolling leukocytes in 100-μm venular segments were counted and compared with baseline measurements. The proximity of arterioles to venules was classified as adjacent (<15 μm) or distant (>15 μm). No significant changes in leukocyte endothelial adherence or arteriolar diameter were noted in group 1 sham or group 3 nonischemic hyperbaric oxygen-treated rats when compared with baseline measurements. A significant increase in adherent leukocytes was observed in group 2 ischemic venules (+14.9 ± 2.5) within 5 minutes of reperfusion, which was maintained for 3 hours. Reperfusion measurements of arteriolar diameter in group 2 ischemic muscle preparations demonstrated an initial vasodilation that was followed at 1 hour by a progressive and severe vasoconstriction (−46.9 ±11.3 percent at 3 hours) in arterioles adjacent to venules that was not seen in distant arterioles. The increase in adherent leukocytes seen in group 2 ischemic venules was significantly reduced by hyperbaric oxygen treatment given during ischemia (group 4) or up to 1 hour during reperfusion (groups 5 and 6). In addition, the progressive ischemic arteriolar vasoconstriction was inhibited in all groups (4, 5, and 6) treated with hyperbaric oxygen. These results suggest that (1) leukocyte venular endothelial adherence and microarteriolar vasoconstriction are important morphologic events leading to reperfusion injury of skeletal muscle, (2) this vasoconstriction is seen primarily in arterioles that are in close proximity to venules, and (3) hyperbaric oxygen treatment does not exacerbate reperfusion injury, but rather appears to protect the microcirculation by reducing venular leukocyte adherence and inhibiting progressive adjacent arteriolar vasoconstriction.

Comparison of Silver Sulfadiazine, Povidone‐Iodine and Physiologic Saline in the Treatment of Chronic Pressure Ulcers

ABSTRACT: The presence of bacteria and local infection is an important factor in the local management of chronic pressure ulcers. For successful closure of the ulcer, the bacterial count should be 105 or less per gram of tissue in the granulating wound. In a prospective randomized study of 45 (eventually 40) hospitalized patients, silver sulfadiazine (Silvadene) cream and povidone‐iodine (Betadine) solution were compared to physiologic saline for effectiveness in preparing pressure ulcers for closure. Quantitative bacteriologic techniques on tissue biopsy specimens were used for objective evaluation. In 100 percent of the ulcers treated with silver sulfadiazine cream (15 patients) the bacterial counts were reduced to 105 or less per gram of tissue within the three‐week test period, compared to 78.6 percent in those treated with saline (14 patients) and 63.6 percent in those treated with povidone‐iodine solution (11 patients). Moreover, the ulcers treated with silver sulfadiazine cream responded more rapidly, with one‐third showing bacterial levels of <105 within three days, and half within a week.

Magnetic resonance imaging of severe frostbite injuries

Frostbite injury causes damage by direct ice crystal formation at the cellular level with cellular dehydration and microvascular occlusion. Acute treatment is well defined with rapid tissue rewarming. Definitive surgical therapy is usually delayed until a clear level of demarcation is seen. Technium (Tc)-99 bone scanning has become the standard imaging study employed within the first several days to assess tissue perfusion and viability. We present 2 patients with severe frostbite injury in which magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) were compared to Tc-99 bone scans. MRI/MRA appears to be superior to bone scanning by allowing direct visualization of occluded vessels, imaging of surrounding tissues, and by showing a more clear-cut line of demarcation of ischemic tissue. MRI/MRA may also allow early intervention in cases of severe frostbite, thus preventing secondary infection and increased cost.

IN VITRO TOXICITY TESTING FOR ANTIBACTERIALS AGAINST HUMAN KERATINOCYTES

The use of cultured human keratinocytes in an in vitro comparison of topical antibacterial toxicity for epithelial cells was examined. The complement of three assessments allows testing of epithelial migration, growth, and survival. The three assessments included (1) flow cytometry for determination of cell survival, (2) a comparison of confluent cell culture growth after antibacterial exposures, and (3) an evaluation of cell migration using a technique of dermal explains to study radial migration. A comparative ranking of the toxicities of the various topical antibacterials was determined with the three assessments. This has confirmed anecdotal reports that many of the topical antibacterials are cell-toxic and may inhibit wound healing. This information can be directly extrapolated to the clinical setting, unlike many of the animal data for wound healing that currently exist.

Diabetic foot infections: fate of the contralateral foot.

Following an initial report urging conservative management of severe diabetic foot infections, the authors have managed 45 patients with a minimum 3-year followup. By using standard principles for soft-tissue infection, 78 percent of the patients healed minor amputation sites and maintained biped ambulation following the initial foot involvement. Only 22 percent required a major amputation at the time of the initial foot involvement. The 45 patients were followed and 22 (or 49 percent) developed a severe infection involving the contralateral foot within 18 months. Although 15 of the 22 patients developing contralateral infection (or 33 percent of the total series) required some type of amputation on the contralateral foot, the conservative approach allowed 64 percent of the patients with severe infections in both feet to maintain biped ambulation. This included 40 percent of the patients who required amputation of some portion of both feet.

The extended pectoralis major myocutaneous flap: uses and indications.

The vascular territory of the pectoralis major muscle and overlying skin was studied by selective intraarterial dye injections in fresh cadavers. The area of skin overlying the anterior chest and abdominal wall beyond the limits of the pectoralis major muscle that can be elevated as an extended myocutaneous flap was determined. The cadaver injections were evaluated to determine the size and shape of the skin island used to reconstruct defects of the head, neck, and upper trunk with an extended skin paddle off the pectoralis major muscle. Pectoralis muscle flaps with variously shaped skin paddles, some extending beyond the limits of the muscle, were used in 27 patients to cover large soft-tissue defects of the upper thorax, face, and floor of the mouth and as a skin tube to reconstruct the cervical esophagus The size of the skin paddle ranged from 5 X 7 cm to 26 X 16 cm. All flaps survived completely, and there were no major donor-site complications.

Five percent mafenide acetate solution in the treatment of thermal injuries.

A 5% mafenide acetate solution was used in the treatment of 669 patients with thermal injuries. This solution was used as the initial topical antibacterial agent in the treatment of the acute burn wound in 276 patients. It was initiated during the intermediate and chronic phases of burn wound therapy in 393 patients. Acid-base derangements did not occur. Discontinuation of therapy because of the patients pain was necessary in fewer than 1% (17 of 669) of all patients treated. The incidence of rash and pruritus was extremely low. Effective antibacterial activity was achieved. This solution appears to be an effective, safe, and versatile antibacterial agent that produces minimal side effects and is useful in all phases of burn wound management.

Soft-tissue calcifications: differential diagnosis and therapeutic approaches.

Calcification of soft tissue may be an unspecific local response or present as only a symptom of a complex underlying disease. Patient approach and treatment vary greatly depending on the cause of soft-tissue calcifications. The review of literature reveals multiple causes but also confusing nomenclature for similar clinical entities. Dystrophic and metastatic soft-tissue calcifications are discerned, but there is also contribution of both types of soft-tissue calcification to some syndromes. Six previously unpublished cases of soft-tissue calcification including Thibikrge- Weissenbach syndrome, scleroderma (progressive systemic sclerosis), calcifying cavernous hemangioma (2 patients), and heterotopic calcifications after burn injury (2 patients) are presented to discuss the differential diagnosis. The correct diagnosis is crucial for successful treatment. Resections of the lateral heads of the gastrocnemius muscles in 2 patients resulted in cure of the problem. The patient suffering from Thibikrge- Weissenbach syndrome had no recurrence during a 30-month postoperative follow-up period. Surgical treatment of scleroderma or soft-tissue calcification after burn injury is aimed toward relief of symptoms. A proposal for patient assessment and indications for surgical correction with regard to soft-tissue calcifications is presented and discussed.

The effects of chronic ketorolac tromethamine (toradol) on wound healing.

Intramuscular ketorolac is a commonly used nonsteroidal anti-inflammatory (NSAI) agent for analgesia in surgical patients. Increasing numbers of surgical patients are chronically taking some form of an NSAI drug. We examined the effects of “chronic” intramuscular ketorolac on the healing of a closed linear surgical wound in the rat. Wistar rats were pretreated with 4 mg per kilogram per day ketorolac intramuscularly prior to receiving dorsal incisional wounds. The ketorolac treatment was continued and after 2 weeks the wounds were excised and separated with a tensiometer to measure mechanical properties. Breaking strength was directly measured, tensile strength was calculated, and collagen concentrations at the wound site were determined. A significant decrease in the mean breaking strength was seen in the ketorolac-treated animals when compared to controls. The ketorolac-treated animals had a mean tensile strength less than the controls, although this difference did not reach statistical significance. The mean collagen concentration of the ketorolac-treated wounds was significantly less than the untreated wounds. Use of ketorolac for just 1 week prior to surgery in rats produced a significant decrease in the breaking strength of their wounds. With the increasing use of ketorolac in surgical patients as well as the increasing use of oral NSAI drugs, more study of this effect is warranted.

Tumours metastatic to the parotid gland

Abstract An unusual series of six patients is presented as a reminder that metastatic tumours to the parotid gland need not arise from primaries limited to the head and neck area. The parotid gland, although a highly unlikely metastatic locus, may indeed be the site of lodgment of metastatic tumour originating at some obscure and distant focus.