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Biomedical subjects

J Boswick

Publications and source records attributed to J Boswick.

12 recordsLinked to original sources
PubMed1997

Implementation of parameters in the expansion ratio of mesh skin grafts.

Expansion of a mesh skin graft depends on factors pertaining to the graft itself as well as on parameters of the meshing device. With regard to the graft, we examine the efficiency of graft handling and thickness of the skin graft. With regard to the parameters of the meshing apparatus, which determine the expansion ratio: (1) d equals the distance between the cutting blades, which will become the width of the mesh ribbons and is an underestimated parameter for expansion; and (2) L equals the length of cut, which determines proportionally the expansion ratio. This length defines the maximal distance of the raw square of the expanded mesh and therefore the healing time by epithelialization. The authors present a mathematical formula of expansion ratio that allows for an objective comparison of skin meshing apparatuses. It is concluded that optimal mesh skin grafting is based on mathematical principles rather than on inventive instrumentation. Furthermore, an analysis of the mechanical parameters as given by the manufacturers is important in anticipating healing time per expansion ratio.

Humans↗
PubMed1995

A review of skin meshers.

Before the widespread clinical acceptance of mesh skin grafting, expansion of full thickness skin had already been reported. The senior authors, who performed the first mesh skingrafts, have tried several variations of instruments starting with a flat block, later using a roller device with staggered cuts (Mesh Dermatome type I), and further a roller with continuous cuts and a grooved carrier (Mesh Dermatome II). Now interchangeable rollers for different expansions (Zimmer Skin Mesher) and several other genuine meshers are available. Other innovations from the literature are mentioned. This article gives a classification and details of the different models. The basic principles are reviewed. A general formula is presented, allowing objective comparison of skin meshers.

Animals↗
PubMed1990

Results of high dose intravenous urokinase for acute myocardial infarction.

To determine the outcome of patients after treatment with high-dose intravenous urokinase (3 million U) 102 patients were prospectively evaluated in the setting of acute myocardial infarction. The first 61 patients received intravenous urokinase as a continuous infusion and the last 41 patients were treated with an initial 1.5 million U intravenous bolus. Sixty-two percent of all patients had patent infarct-related arteries by the time of immediate angiography (median time 2.2 hours), which was performed in all patients. There was no significant difference in patency rates between patients treated with or without an initial intravenous bolus. Twenty-eight (28%) patients developed clinical evidence of recurrent ischemia (death, reocclusion, emergency angioplasty, urgent bypass surgery) during hospitalization, whereas only 7 (7%) developed angiographically documented reocclusion. Of 28 patients who failed to achieve successful reperfusion at the time of immediate catheterization, rescue angioplasty was technically successful in establishing reperfusion in all but 1 patient. No significant improvement in median global left ventricular function was seen between immediate (48%) and follow-up catheterization (48%). Significant bleeding complications were unusual except in 1 patient who experienced an intracranial hemorrhage. Eight (8%) patients died during hospitalization. Therefore, the use of high-dose intravenous urokinase in patients with acute myocardial infarction is associated with a 62% patency rate, a low incidence of reocclusion and bleeding complications and a high technical success rate with rescue angioplasty at the time of immediate catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Use of initial ST-segment deviation for prediction of final electrocardiographic size of acute myocardial infarcts.

The decision to administer thrombolytic therapy for limitation of acute myocardial infarction (AMI) size must occur when only the history, physical examination and 12-lead electrocardiogram of a patient are available. A method that could quickly assess the amount of jeopardized myocardium would greatly aid the physician. This study developed formulas from 68 anterior and 80 inferior AMI patients using the extent of initial ST-segment deviation (ST delta) to predict the final AMI size estimated by the Selvester QRS score in a population not receiving reperfusion therapy. Inclusion required: initial anterior or inferior AMI; admission electrocardiogram less than or equal to 8 hours after the onset of symptoms with evidence of epicardial injury; elevated creatine kinase-MB; a predischarge electrocardiogram taken greater than or equal to 72 hours after admission; and no AMI extension before the predischarge electrocardiogram. The extent of epicardial injury was quantified by counting the number of leads with greater than or equal to 0.1 mm ST delta, by the sum (sigma) of ST delta in all leads and by the sigma ST delta in the lead groups associated with each AMI location. These results were compared to the AMI size estimated from the predischarge electrocardiogram. Univariable and multivariable analyses generated these formulas for AMI size: anterior = 3[1.5 (number leads ST increases) - 0.4]; inferior = 3[0.6 (sigma ST increases II, III, aVF) + 2.0]. Thus, formulas based on quantitative measurements of ST delta on the admission electrocardiogram are predictive of final QRS-estimated AMI size, and may be useful in determining the efficacy of acute reperfusion therapy.

Electrocardiography↗
PubMed1988

Quantitative analysis of right and left ventricular infarction in the presence of postinfarction ventricular septal defect.

To quantitate the amount of right and left ventricular infarction in patients dying with postinfarction ventricular septal defect (PIVSD), hearts from 54 patients with anterior or inferior myocardial infarction were studied at autopsy. Fifteen hearts had myocardial infarction with PIVSD and 39 hearts had infarction without PIVSD and were used as a comparison group. All infarcts were sized histologically and the percent of each ventricle infarcted was quantitated by computer-assisted planimetry. The pathologic substrate for PIVSD was diffuse coronary artery disease with acute thrombosis resulting in transmural confluent infarction. Within the PIVSD group, there was significantly more left ventricle involved in anterior infarctions than in inferior infarctions (p less than .04). Conversely, there was more right ventricular infarction in inferiorly located myocardial infarctions with resulting PIVSD (p = .059). When infarctions resulting in PIVSD were compared with infarctions not resulting in PIVSD, the PIVSD group was characterized by larger left and right ventricular infarcts irrespective of infarct location (p less than .003). The incidence of right ventricular infarction was 100% in the PIVSD group (p less than .0001). Twelve of the 15 patients with PIVSD (80%) developed cardiogenic shock within 48 hr of septal rupture. The high incidence of shock and the rapid deterioration may have been secondary to right ventricular infarction in these patients. Therefore, infarcts resulting in PIVSD and subsequent death are characterized by a high incidence of right ventricular infarction. Significantly more infarction of the right ventricle is seen in either anterior or inferior infarctions resulting in PIVSD compared with infarctions not resulting in PIVSD. PIVSD complicating inferior infarctions is associated with the greatest amount of right ventricular infarction.

Aged↗
PubMed1987

Identification of the optimal electrocardiographic leads for detecting acute epicardial injury in acute myocardial infarction.

Current coronary care electrocardiographic (ECG) monitoring techniques are aimed at detection of cardiac arrhythmias rather than myocardial ischemia. However, in patients with acute myocardial infarction (AMI) who undergo reperfusion therapy, monitoring ST-segment deviation could provide an early noninvasive indicator of coronary artery reocclusion. In this study, the admission 12-lead ECGs of patients with initial AMI were used to propose optimal lead locations for ST-segment monitoring. The study population was selected from consecutive Duke University Medical Center admissions during 1965 to 1981 who met the following inclusion criteria: chest pain for no more than 8 hours, initial AMI documented by ECG and 3 of 4 enzyme criteria, greater than or equal to 0.1 mV (1 mV = 10 mm) of ST elevation in at least 1 of the standard 12 leads (not aVR) on admission ECG, and no ECG evidence of conduction disturbances, ventricular hypertrophy or tachycardia. ST-segment deviation was quantified; AMI location was assigned based on the lead with maximal deviation. Of the 80 patients who had an inferior AMI, lead III was both the most frequent location for ST elevation (94%) and the most common site with maximal ST deviation. Lead V2 had the highest incidence of ST-segment depression (60%). In the 68 patients who had an anterior AMI, lead V2 had the highest frequency of ST elevation (99%). Leads V2 and V3 were the most common sites of maximal elevation. Thus, for monitoring ST deviation, leads III and V2 may be superior to leads II and V1, which are commonly used in arrhythmia monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1985

Hydrocarbon contact injuries.

Cutaneous injury caused by exposure to gasoline and other hydrocarbons is a clinical entity with potentially life-threatening effects. We report four cases of such injury. One patient developed full-thickness skin loss following gasoline immersion, and another developed severe systemic complications following contact with a carburetor cleaning solvent. Initial therapy should consist of removal of solvent-containing clothing and extensive lavage or soaking with water, followed by wound care that is generally similar to that used in the treatment of partial-thickness burns. In most cases this includes debridement, topical antimicrobial agents, and dressing changes. Severe pulmonary, cardiovascular, neurologic, renal, and hepatic complications may accompany hydrocarbon absorption, particularly in cases involving gasolines containing lead additives. Therefore immediate surgical debridement should be considered if there is suspicion of continued absorption of toxic compounds from the wound.

Absorption↗
PubMed1984

Characterization of the immunosuppressive effect of burned tissue in an animal model.

The immunosuppressive effect of burned tissue was studied using a mouse burn model. To evaluate the immunologic status an in vivo measure of cell-mediated immunity (CMI) involving contact sensitization of mice by painting the skin with dinitrofluorobenzene was used; mice were challenged 5 days later by painting the ear with the same antigen. Ear swelling in response to antigenic challenge was used as a quantitative measure of CMI; diminution in ear swelling in treatment mice compared to sensitized, unburned control mice indicated the degree of immunosuppression. A full-thickness steam burn covering 20% body surface ares (BSA) was profoundly immunosuppressive as reflected by ear swelling of 45 to 60% of that found in normal mice; partial thickness burns and burns of 10% BSA extent were not significantly immunosuppressive. Transfer into unburned mice of burned skin equivalent in size to a 20% BSA burn eschar resulted in marked immunosuppression, but transfer of smaller amounts of burned skin, or of larger amounts of unburned skin and normal and burned liver tissue, did not produce immunosuppression. Mice receiving a very high-temperature (300 degrees C), dry burn were only slightly more suppressed than mice receiving a standard steam burn. Normal immunity was preserved in burned mice which received daily application of cerium nitrate to the wound for 7 days, but application of other topical agents commonly used in burn treatment did not preserve immunity. Postburn immunosuppression thus appears related quantitatively to toxic factors in burned skin, and these toxic factors can be abrogated in burned mice by the topical application of cerium nitrate.

Animals↗
PubMed1984

Recovery of skeletal muscle after laceration and repair.

Few data are available regarding structural and functional recovery of lacerated skeletal muscle after repair. This study used the extensor digitorum longus muscle of rabbits to document recovery after laceration and repair and a healing period of 12 weeks. Completely lacerated muscles recovered approximately 50% of their ability to produce tension but were able to shorten to 80% of normal. Partially lacerated muscle bellies recovered approximately 60% of their ability to produce tension and normal ability to shorten. Histologic specimens revealed that the lacerations did not cause necrosis of either segment. After the recovery period, histologic and histochemical sections revealed that the distal segment initially isolated from the nerve supply showed histologic changes of fiber atrophy and size variability, increased fibrosis, and nuclear centralization suggestive of denervation. Dense scar separated the two fragments. Data show that skeletal muscle can recover useful but not normal function after laceration and repair.

Animals↗