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Biomedical subjects

A J Singer

Publications and source records attributed to A J Singer.

At least 37 records · Page 2Linked to original sources
PubMed2000

Histopathologic effects of cutaneous tape stripping in pigs.

OBJECTIVE: The stratum corneum (SC) is the major barrier to topical absorption of medications. Skin tape stripping (TS) removes the stratum corneum, allowing more rapid absorption of drugs such as local anesthetics. Prior to evaluating TS in human clinical trials, this study was performed to evaluate its immediate and delayed histopathologic effects in swine. METHODS: This was a prospective, interventional, longitudinal, experimental animal study using two isoflurane-anesthetized young swine. Cellophane tape was applied to the skin of clipped swine flanks and peeled away 10, 15, 20, 25, or 30 times. Each level of tape stripping was performed three times in each pig. Full-thickness biopsies were taken at 30 minutes and two weeks later for blinded histopathologic evaluation by a dermatopathologist using randomly ordered hematoxylin-and-eosin-stained tissue sections and conventional light microscopy. The absolute thickness of the cornified layer was measured and compared with normal (unstripped) cornified layer. RESULTS: Tape stripping up to 30 times produces thinning of the SC without detectable changes in the underlying epidermis and dermis at 30 minutes and 14 days post-stripping. The degree of thinning was proportional to the number of tape applications. Complete recovery of the cornified layer was noted at two weeks. There were no adverse effects, such as infection, scarring, or inflammatory cell infiltrates. CONCLUSIONS: Under the conditions studied, TS not only appears safe, but appears to produce no long-term sequelae.

Animals↗
PubMed2000

The effects of epidermal debridement of partial-thickness burns on infection and reepithelialization in swine.

OBJECTIVE: Early postburn debridement of burn blisters is controversial. This study was conducted to compare rates of infection and reepithelialization in debrided vs nondebrided second-degree burns in swine. METHODS: This was a prospective, blinded, controlled, experimental trial using isoflurane-anesthetized swine. Standardized partial-thickness burns were inflicted by applying an aluminum bar preheated to 80 degrees C to the backs and flanks of two young pigs for 20 seconds. In half of the burns the necrotic epidermis was manually debrided. All burns were randomly treated with octylcyanoacrylate spray (OCA) or dry gauze (C). Full-thickness biopsies were taken at 7, 10, and 14 days for blinded histopathologic evaluation. The primary outcomes were the proportions of infected burns at days 7 and 10 and the proportion of completely reepithelialized burns at day 14. Burns were considered infected in the presence of intradermal neutrophils containing bacteria (intraobserver agreement, K = 1.00). A secondary outcome was the proportion of burns with the presence of scar tissue (abnormal collagen under polarized light; intraobserver correlation, K = 0.93). Chi-square tests were used for group comparisons. This study had 90% power to detect a 40-percentage-point difference in infection rates (alpha = 0.05). RESULTS: A total of 126 biopsies from 42 burns were available for review. Infection rates were higher in the debrided burns both at day 7 (55% vs 4.5%, p < 0.001) and at day 10 (65% vs 9%, p < 0.001) after injury. The proportion of nondebrided burns that were completely reepithelialized was higher at days 10 (68% vs 0%, p < 0.001) and 14 (100% vs 65%, p = 0.003). The presence of scar tissue was more common in debrided burns (75% vs 4.5%, p < 0.001). Burns treated with OCA had fewer infections than controls (4% vs 55%, p < 0.001). Fewer OCA-treated debrided burns were reepithelialized at 14 days than those that were not debrided (30% vs 100%, p = 0.001). CONCLUSIONS: Under the current study conditions, early postburn epidermal debridement of second-degree burns resulted in more infections and slower reepithelialization rates in swine. The effects of early postburn epidermal debridement in humans should be explored.

Animals↗
PubMed2000

Octylcyanoacrylate for the treatment of contaminated partial-thickness burns in swine: a randomized controlled experiment.

OBJECTIVE: To compare infection and reepithelialization rates of contaminated second-degree burns treated with octylcyanoacrylate (OCA), silver sulfadiazine (SSD), polyurethane (PU) film, and dry gauze (control; C) in swine. METHODS: Eighty standardized burns were created by applying an aluminum bar preheated to 80 degrees C to the backs and flanks of young pigs for 20 seconds. All burns were immediately contaminated with 0.1 mL of Staphylococcus aureus 10(5)/mL and randomly treated with OCA spray, SSD, PU, or dry gauze (C). Full-thickness biopsies were taken at 3, 7, and 14 days for blinded histopathologic evaluation using hematoxylin and eosin (H&E)-stained slides. Burns were considered infected in the presence of interstitial reticular dermal neutrophils containing bacteria (intraobserver agreement, kappa = 1.00). Quantitative wound cultures were performed on a second day-3 specimen. RESULTS: At day 3, wound infection rates were 30% (OCA), 50% (SSD), 55% (PU), and 50% (C); p = 0.40 (Kruskal-Wallis test). At day 7, infection rates were 35% (OCA), 85% (SSD), 70% (PU), and 65% (C); p = 0.01. Median bacterial counts at day 3 were 6,500 (OCA), 20,000 (SSD), 1,000,000 (PU), and 650,000 (C); p = 0.29. The proportion of completely reepithelialized wounds at day 14 were 75% (OCA), 90% (SSD), 85% (PU), and 90% (C); p = 0.50. CONCLUSIONS: Treatment of contaminated partial-thickness burns with OCA spray resulted in fewer infections at one week than with the other three treatments.

Animals↗
PubMed2000

Development of a histomorphologic scale to quantify cutaneous scars after burns.

OBJECTIVE: Cutaneous wound healing in adults invariably results in scarring; however, there are few scales to quantify the degree of such scarring. The authors developed a histomorphologic scale for quantifying scarring after cutaneous burn injury. METHODS: As part of a randomized trial comparing a variety of burn therapies, 40 partial-thickness burns were created on the backs and flanks of anesthetized pigs and treated with a tissue adhesive, antibiotic ointment, occlusive dressing, or dry gauze. Gross scar appearance was independently assessed by two investigators at 90 days on a 100-mm visual analog scale (VAS) marked "best appearance" at the high end. One of the investigators repeated the observation 30 days later. Full-thickness biopsies were taken 90 days after injury and evaluated histologically by a dermatopathologist for the presence of hyperkeratosis, epidermal hyperplasia, presence and depth of scar (defined as abnormally oriented collagen under polarized light), fibroplasia, vascular proliferation, and absence of adnexa, including hair follicles, apocrine glands, and smooth muscles. One point was assigned for each category in the presence of a normal finding, whereas an abnormal finding was assigned a score of zero. The normal dermis (absence of abnormal collagen) was given a score of 3, while decreasing scores of 2 to 0 were given for progressively deeper scars (i.e., 2 for papillary dermis, 1 for upper half of reticular dermis, and 0 for deep dermal lower half). The total histomorphologic score was derived by adding the scores on the individual items. The score ranges from 0 to 10 from worst scarring to absence of scarring, respectively. A subset of observations was evaluated a second time by one of the observers one month later. Intraobserver reliability of the histomorphologic scale was assessed with Spearman's correlation. Inter- and intraobserver Pearson's correlations for the gross scar VAS were calculated, and the correlation between gross and histomorphologic scores was assessed. RESULTS: Intraobserver correlation for individual histomorphologic categories ranged from 0.19 to 1.00. Intraobserver correlation for the total histologic score was 0.95. Inter- and intraobserver correlations for the gross scar VAS were 0.8 each. Correlation between the histomorphologic scale and the gross scar VAS was 0.38. CONCLUSIONS: A new reliable histomorphologic method for quantifying and scoring cutaneous scars is described together with a reliable scar VAS. However, these two scales are not highly correlated.

Adult↗
PubMed2000

Standardized burn model using a multiparametric histologic analysis of burn depth.

OBJECTIVE: Burn depth and extent determine prognosis and therapy. The current classification into first-, second-, and third-degree burns is crude, making comparisons between studies difficult. The authors standardized a reproducible burn model and a precise histopathologic method for describing burn depth in swine. METHODS: This was a prospective, cross-sectional interventional animal study. Eighteen paired sets of burns were inflicted on the clipped flank skin of two anesthetized domestic pigs with a 2.5 cm by 2.5 cm by 7.5 cm aluminum bar preheated in water to 50 degrees C, 60 degrees C, 70 degrees C, 80 degrees C, 90 degrees C, degrees C or 100 degrees C. The bar was applied for 10, 20, or 30 seconds. Full-thickness skin biopsies were obtained 30 minutes after injury for blinded histopathologic evaluation using hematoxylin and eosin staining. Two dermatopathologists made two sets of measurements and were masked to each other's evaluations. The depth of injury was measured with an ocular microtome for each of five dermal parameters: collagen discoloration, intercollagen basophilic material, endothelial cell necrosis, epithelial cell necrosis, and mesenchymal cell necrosis. The correlation between burn depths of the paired sets of experiments was calculated to assess the reliability of the model. Inter- and intraobserver correlations were calculated to assess the reliability of the scale. Analysis of variance (ANOVA) was used to assess the relation between temperature and exposure times on burn depth. RESULTS: Depth of injury for all five dermal elements was related to temperature and exposure times (ANOVA, p < 0.001 for each). The depth of injury in the paired sets of burns was highly consistent (Pearson correlation, range = 0.88-0.95). Inter- and intraobserver correlations were excellent for all measured elements (range = 0.91-0.97 and 0.95-0.99, respectively). CONCLUSIONS: The authors describe a simple and reproducible animal burn model and histopathologic scale for measuring burn depth that they believe will facilitate standardization and comparison within future burn studies.

Animals↗
PubMed2000

Research fundamentals: selection and development of clinical outcome measures.

Clinical outcomes measure patient health or well-being. The choice of an outcome measure for use in a clinical trial or study is complex. It is even more difficult when no appropriate outcome measure exists, necessitating the development of a novel one. The ideal clinical outcome should be credible, comprehensive, sensitive to change, accurate, biologically sensible, and feasible. This paper describes the attributes of clinical outcomes and illustrates how to develop novel outcomes, using as an example the authors' experience in developing a wound cosmesis outcome measure.

Humans↗
PubMed2000

Pretreatment of lacerations with lidocaine, epinephrine, and tetracaine at triage: a randomized double-blind trial.

OBJECTIVE: Pretreatment of lacerations with topical anesthetics reduces the pain of subsequent anesthetic injection yet requires time. This study was conducted to determine the ability of triage nurses to identify lacerations necessitating closure and pretreat them with a topical anesthetic and to compare the pain levels of lidocaine injection in lacerations pretreated with LET (lidocaine 2%, epinephrine 1:1,000, tetracaine 2%) vs a placebo. METHODS: This was a double-blind, randomized clinical trial that included consecutive emergency department patients aged > or = 1 year with clean, non-bite lacerations < or = 6 hours old. At triage the lacerations were randomized to LET solution or a placebo containing epinephrine 1:1,000. At examination an emergency practitioner assessed the laceration edges for the presence of blanching and adequacy of anesthesia to a 27-gauge needlestick. At the practitioner's discretion, supplemental lidocaine was infiltrated through the wound and the patient (or guardian) recorded the pain of infiltration on a 100-mm visual analog scale marked "most pain" at the high end. The mean levels of pain of lidocaine infiltration were compared between groups with a t-test and the proportions of adequately anesthetized wounds were compared with a chi2 test. A sample of 40 patients had 80% power to detect a 20-mm between-group difference in the pain of injection (alpha = 0.05). RESULTS: Of 43 patients enrolled (mostly children and males), 22 received LET and 21 placebo. The groups were similar for baseline characteristics. Lacerations in the LET group were more frequently adequately anesthetized (46% vs 14%, p = 0.03), and LET patients experienced less pain from injection than controls (22 mm vs 42 mm, p = 0.02). CONCLUSIONS: Application of LET by triage nurses is more effective than placebo in adequately anesthetizing simple lacerations in normal hosts and decreases the pain of local anesthetic infiltration.

Administration, Topical↗
PubMed1999

The effects of low-frequency ultrasound on Staphylococcus epidermidis.

Low frequency ultrasound (LFUS) significantly enhances skin permeability to a variety of drugs; however, its bacterial effects have not been well studied. Staphylococcus epidermidis organisms were grown and standardized to 10(5) cfu/ml 24 h prior to investigation and suspended in normal saline. LFUS was applied with two probes immersed in the bacterial suspensions over a range of suspension volumes, intensities, and exposure times. The suspension temperature was measured, and a sample was removed, streaked onto blood agar plates, and incubated at 37 degrees C for 24 h. Quantitative bacterial counts were then obtained. LFUS resulted in significant reductions in bacterial counts that correlated with fluid temperature. Probe size and ultrasound intensity appeared to affect bacterial counts, but were also correlated with temperature. Bacterial growth was minimal with temperatures exceeding 45 degrees C. While LFUS can reduce bacterial counts, these conditions have the potential to cause burns in humans.

Colony Count, Microbial↗
PubMed1999

Laceration management.

In 1996, almost 11 million lacerations were treated in emergency departments throughout the United States. Although most lacerations heal without sequelae regardless of management, mismanagement may result in wound infections, prolonged convalescence, unsightly and dysfunctional scars, and, rarely, mortality. The goals of wound management are simple: avoid infection and achieve a functional and aesthetically pleasing scar. Recent US Food and Drug Administration approval of tissue adhesives has significantly expanded clinicians' wound closure options and improved patient care. We review the general principles of wound care and expand on the use of tissue adhesives for laceration repair.

Adolescent↗
PubMed1999

The effectiveness of ice as a topical anesthetic for the insertion of intravenous catheters.

In a paired clinical trial, the effectiveness of ice in reducing the pain of intravenous catheter placement was assessed in 28 adult volunteers. An ice pack was placed over one arm for 10 minutes, followed by insertion of an 18-gauge angiocatheter in both arms. Patients recorded their pain assessment after each venipuncture on a previously validated 100-mm visual analog scale (VAS) and identified their preferred method for the procedure (pretreatment with ice or no pretreatment). The mean pain score for catheter placement on arms pretreated with ice was 27.5+/-15.9 mm; the mean pain score for the control arms was 34.2+/-21.6 mm (P = .17). Most patients (61%) preferred no pretreatment (P = .014). Although most men (75%) preferred no pretreatment, 75% of women preferred pretreatment with ice (P = .014). Future studies should examine whether ice is effective at reducing pain from other more painful procedures and whether the response to ice is gender-related.

Administration, Topical↗
PubMed1999

Evolution of abstracts presented at the annual scientific meetings of academic emergency medicine.

There has been a general trend in medicine towards greater sophistication in research design. In order to assess this trend in emergency medicine we compared the characteristics of abstracts presented at the 1974, 1983, 1989, and 1997 annual scientific meetings of academic emergency medicine. All 870 abstracts were reviewed by 1 of 3 investigators who determined research design attributes using a standardized classification scheme that has good interrater reliability. Over the last 25 years the following trends were noted: more surveys (0% v1% v3% v8%, P = 0.002), more randomized studies (0% v10% v12% v15%, P = 0.05), and more blinded studies (0% v7% v5% v11%, P = 0.01). Tests of statistical significance were reported with increasing frequency (8% v26% v59% v69%, P < 0.001) as were power calculations (0% v0% v1% v3%, P = 0.02). During the study period there were also increases in the median number of authors, proportion of foreign lead authors, and the proportion of studies involving human subjects. These results reflect considerable improvement in the degree of research design sophistication reported in selected abstracts of academic emergency medicine over the study period. Further strategies to assure continued enhancement of emergency medicine research should be explored.

Abstracting and Indexing↗
PubMed1999

Evolution of abstracts presented at the annual scientific meetings of academic emergency medicine.

There has been a general trend in medicine toward greater sophistication in research design. To assess this trend in emergency medicine, we compared the characteristics of abstracts presented at the 1974, 1983, 1989, and 1997 annual scientific meetings of Academic Emergency Medicine. All 870 abstracts were reviewed by 1 of 3 investigators who determined research design attributes using a standardized classification scheme that has good interrater reliability. Over the last 25 years, the following trends were noted: more surveys (0% v1% v3% v8%, P=.002), more randomized studies (0% v10% v12% v15%, P=.05), and more blinded studies (0% v7% v5% v11%, P=.01). Tests of statistical significance were reported with increasing frequency (8% v26% v59% v 69%, P < .001), as were power calculations (0% v0% v1% v3%, P=.02). During the study period, there were also increases in the median number of authors, proportion of foreign lead authors, and the proportion of studies involving human subjects. These results reflect considerable improvement in the degree of research design sophistication reported in selected abstracts of academic emergency medicine over the study period. Further strategies to assure continued enhancement of emergency medicine research should be explored.

Bibliometrics↗
PubMed1999

Comparison of topical anesthetics and vasoconstrictors vs lubricants prior to nasogastric intubation: a randomized, controlled trial.

OBJECTIVE: To determine whether pre-treatment of the nose and throat with topical anesthetics and vasoconstrictors would reduce the pain associated with nasogastric (NG) intubation. METHODS: This was a prospective, randomized, controlled trial assessing the pain of NG intubation in patients pretreated with topical anesthetics and vasoconstrictors vs surgical lubricants alone. The subjects were 40 alert, cooperative adult patients requiring NG intubation without allergies to the study medications or contraindications to their use from a suburban university-based ED. The patients in the experimental group had phenylephrine 0.5% sprayed in their noses followed by instillation of 5 mL of 2% lidocaine jelly. Their throats were sprayed with 2% tetracaine and 14% benzocaine. The control patients received intranasal lubrication only. The primary outcome measured was pain of NG intubation on a 100-mm visual analog scale. Other outcomes included nasal pain, discomfort from gagging, and the incidences of vomiting, choking, and epistaxis. RESULTS: The mean age (+/-SD) was 54.8+/-22.3 years; 20 (50%) were female. The patients who had a combination of topical anesthetics and vasoconstrictors inserted prior to NG intubation experienced significantly less overall pain/ discomfort than did the control patients [28.6 mm (95% CI = 17.3 to 39.9 mm) vs 57.5 mm (95% CI = 44.9 to 70.1 mm), p = 0.001]. The patients in the experimental group also experienced significantly less nasal pain than did the patients in the control group [18.1 mm (95% CI = 8.0 to 28.2 mm) vs 44.4 mm (95% CI = 30.4 to 58.6 mm), p = 0.003] and significantly less discomfort from gagging than the patients receiving pretreatment with a lubricant alone [24.1 mm (95% CI = 11.1 to 37.1 mm) vs 50.9 mm (95% CI = 36.7 to 65.1 mm), p = 0.006]. There was no between-group difference in the frequencies of adverse effects. CONCLUSIONS: Use of topical lidocaine and phenylephrine for the nose and tetracaine with benzocaine spray for the throat prior to NG intubation results in significantly less pain and discomfort than use of a nasal surgical lubricant alone. Widespread use of topical anesthetics and vasoconstrictors prior to NG intubation is recommended.

Administration, Topical↗
PubMed1999

Octylcyanoacrylate for the treatment of partial-thickness burns in swine: a randomized, controlled experiment.

OBJECTIVE: To compare re-epithelialization rates of superficial partial-thickness burns treated with octylcyanoacrylate (OCA), silver sulfadiazine (SSD), and dry gauze (controls) in swine. METHODS: This was a prospective, longitudinal, blinded, controlled, experimental trial using anesthetized swine. Sixty-three standardized burns were created by applying an aluminum bar preheated to 80 degrees C for 20 seconds to the flanks of four young pigs. Three equal sets of 21 burns were randomly treated with OCA spray, SSD, or dry gauze (controls). Full-thickness biopsies were taken after 30 minutes and at seven and 14 days for blinded histopathologic evaluation by two dermatopathologists using hematoxylin and eosin staining. The percent of wound re-epithelialization was measured at days 7 and 14, calculated by dividing the length of the regenerated epidermis by the measured width of the biopsy. Analysis of variance (ANOVA) and repeated-measures ANOVA controlling for the individual pig were used for comparisons among groups. This study had 80% power to demonstrate a large between-group difference in percent re-epithelization (alpha = 0.05). RESULTS: There were 63 burns and 126 biopsies. Ten biopsies were excluded for technical reasons. At seven days, there was a significant between-group difference in percent re-epithelialization. Percent re-epithelialization was greatest in the OCA group (65.0%), followed by the SSD group (37.6%), and lowest in the control group (8.8%). At 14 days, all wounds demonstrated near complete re-epithelialization and there was no significant difference in the percent of re-epithelialization among the groups. There was only one wound infection in the OCA group. CONCLUSIONS: Under these study conditions, treatment of partial-thickness burns with OCA spray resulted in a higher percent of re-epithelialization at seven but not 14 days when compared with both SSD and control, with no significant increase in infection rates. Future studies should evaluate the use of OCA for the treatment of burns in humans.

Analysis of Variance↗
PubMed1999

Comparison of the palatabilities of standard and superactivated charcoal in toxic ingestions: a randomized trial.

OBJECTIVE: To compare the palatabilities of two activated charcoal formulations in patients with potentially toxic ingestions. METHODS: Prospective double-blinded randomized controlled trial comparing the palatability of standard charcoal [LiquiChar (LC)] with that of a superactivated granulated form [(CharcoAid G (CA)]. Alert adult patients with known or suspected toxic ingestions requiring activated charcoal were randomly assigned to receive 60 g of either LC or CA diluted in a cola beverage to a volume of 340 mL. Standardized forms were used to collect data on patient demographics, time required to drink the charcoal, the remaining volume of activated charcoal, and any adverse reactions. Patients rated the palatability of the activated charcoal on a 100-mm visual analog scale (VAS) with 100 indicating "best imaginable beverage." Telephone follow-up was obtained to identify complications. Student's t-tests or Mann-Whitney U tests were used to compare continuous variables (e.g., VAS, time, age). Fisher's exact tests were used to compare categorical variables. This study had a power of 0.9 to detect a 20-mm difference in the VAS, alpha = 0.05. RESULTS: There were 60 patients enrolled; 29 drank LC, 31 drank CA. Mean age was 34 years; 68% were female. The groups were similar for age, time from ingestion, ingested agents, time required to drink charcoal, and remaining volume. There were more females in the LC group. Patients receiving CA had significantly higher palatability scores than those receiving LC [35.9 (95% CI = 22.5 to 49.3 mm) vs 19.0 mm (95% CI = 9.3 to 28.6 mm) p = 0.04]. None of the patients aspirated. Of seven patients who vomited, five were given LC (p = 0.25). CONCLUSIONS: CharcoAid is more palatable to patients with toxic ingestions than the standard nongranulated form. Use of the granular charcoal may improve patient compliance.

Administration, Oral↗
PubMed1999

Comparison of patient and practitioner assessments of pain from commonly performed emergency department procedures.

STUDY OBJECTIVE: To compare patient and practitioner assessments of pain associated with commonly performed emergency department procedures and use of anesthetics before these procedures. METHODS: This was a prospective, observational, cross-sectional study conducted at a university-based ED with a convenience sample of ED patients. Research assistants recorded the procedure performed and historical and demographic information on standardized data collection instruments. After each procedure, both the patient and practitioner independently recorded assessments of patient pain on a 100-mm visual analog scale (VAS). Use of preprocedure anesthetics and patient preferences regarding their use were also identified. Categorical variables were analyzed by chi(2) tests. Patient and practitioner VAS scores were compared using a paired t test; alpha was preset at .05. Correlation coefficients were calculated to assess correlation between patient and practitioner pain scores. RESULTS: A total of 1,171 procedures were evaluated for the 15 most common procedures performed. The mean patient age was 42.8+/-18.7 years and 46.1% were male. Overall, the mean patient VAS was 20.8 mm+/-25.1 mm; the mean practitioner VAS was 23.5 mm+/-20.3 mm. The mean difference between groups was 3.0 mm (95% confidence interval [CI], 1.3 to 4.1). Correlation between patient and practitioner pain scores for individual procedures was poor to fair (r=.26 to.68). The most painful procedures according to patients in descending order were nasogastric intubation, abscess drainage, fracture reduction, and urethral catheterization. Local anesthetics were administered in 12.8% of procedures yet would be requested before similar future procedures by 17.1% of patients. Patients who would choose local anesthetics in the future gave higher pain scores than those who would not (43.3 mm versus 16.3 mm; mean difference=27.0 mm, 95% CI, 22.2 to 31.8 mm). CONCLUSION: The most painful procedures for ED patients were nasogastric intubation, incision and drainage of abscesses, fracture reduction, and urethral catheterization. Although practitioners also identified these procedures as most painful, the correlation between patient and practitioner pain assessments in individual patients was highly variable. Overall use of anesthetics before these procedures was low. Practitioners should be attentive to their patients' individual anesthetic needs before performing painful procedures.

Adult↗