Biomedical subjects
W S McDonald
Publications and source records attributed to W S McDonald.
Priorities in the treatment of facial fractures for the millennium.
Although certain principles for management of facial fractures have not changed, new avenues reach this goal with greater precision and less morbidity. By reviewing these recent developments one can see the enormous potential for future developments in technology, techniques, and biomaterials. Development of tertiary care centers for the multiple trauma victim has improved management of facial trauma by bringing a large experience to a team of individuals where creativity flourishes. Major leaps in diagnostic skills and technology now allow us to answer some to the controversial treatment issues in facial trauma. This article hopes to review some old concepts and look at new approaches in managing facial fractures.
Approaches to cleft lip and palate repair.
Facial clefts remain one of the most common congenital anomalies encountered by plastic surgeons. Over the last few decades, surgical results have continued to improve due to the interdisciplinary approach to this complex clinical problem.
The "facelift" flap for reconstruction of cheek, lateral orbit, and temple defects.
BACKGROUND: Large defects of the cheek, lateral orbit, zygomatic arch, or the lower temple pose challenges for reconstruction. These defects can be elegantly reconstructed using the "facelift" flap. OBJECTIVE: The facelift flap is a large advancement flap with a rotational component based on rhytidectomy principles. METHODS: Redundant skin from the lower cheek is used as the donor tissue, which is advanced cephalad and posteriorly. Flap design varies slightly for men and women depending on characteristics of the external ear and ear lobe as well as the position and density of the preauricular hairline. Extensive undermining is critical to reduce tension on the flap and allow for complete closure. Traction provided by an assistant aids in the undermining. Specialized instruments are helpful when performing this flap. Rhytidectomy scissors, multipronged skin rakes, hand-held fiberoptic lighted retractor, and insulated forceps are particularly useful. Correct trimming of the flap and ear lobe placement without tension on the lobe are essential for a good cosmetic result. A large standing cone is excised retroauricularly such that the scar is hidden primarily behind the ear. RESULTS AND CONCLUSION: The facelift flap gives superior and elegant results for reconstruction of large cutaneous defects involving the cheek, lateral orbit, zygomatic arch, and lower temple.
Retinoic acid and CO2 laser resurfacing.
The purpose of this study was to analyze the effect of retinoic acid on wound healing and depth of injury in an animal skin model resurfaced with a CO2 laser. The dorsal skin of 21 Hartley guinea pigs was divided into halves. One-half received a daily application of 0.05% retinoic acid for 28 days, whereas the other half served as the control. The animals were divided into three treatment groups of seven animals. Group A was laser resurfaced with one pass of the Coherent UltraPulse CO2 laser (300 mJ, 60 W, density 40 percent). Group B received two passes, and group C received three passes. Histologic studies were obtained before laser resurfacing and days 1, 4, and 7 after resurfacing. Depth of injury, thickness, number of squamous cell and granular cell layers, and epithelialization rates were measured. We found that the depth of injury was statistically less in animals pretreated with retinoic acid. Granular cells were thicker and more numerous at day 4 in pretreated animals but similar to controls by day 7. Animals pre-treated with retinoic acid overall seemed to heal wounds earlier. In conclusion, pretreatment with retinoic acid may reduce the depth of injury in laser resurfacing and speed healing rates.
Management of orbital fractures.
Motor vehicle accidents have a high association with orbital injuries. A thorough clinical examination is essential, especially an ophthalmic examination. Radiographic analysis is an important aspect of diagnosis. Plain films can be obtained emergently, but high resolution CT scans with axial and coronal planes provide more accurate information. Zygomatic complex fractures are the most common injuries involving the orbits, with naso-orbito-ethmoid fractures and internal orbital fractures following. Autogenous bone, allografts, or synthetic material can be used for repair of defects located in the anterior or middle part of the orbital floor. Multi-team approach is important in the comprehensive management of these complex injuries.
Frontonasal encephalocele and associated congenital brain tumor.
A rare case of frontonasal encephalocele associated with a congenital brain tumor is presented. We describe our combined extracranial and intracranial approach to correction of frontonasal encephaloceles. A discussion of frontonasal encephaloceles and neonatal brain tumors follows, with a discussion of embryopathogenesis and surgical correction.
Debridement of bacterial and particulate-contaminated wounds.
Debridement of contaminated wounds is an essential component of uncomplicated wound healing. Efficient techniques should be capable of removing bacteria as well as foreign matter because of the well-known ability of foreign bodies to potentiate infection. We have compared the ability of current debridement techniques with the relatively new ultrasound debridement to clean wounds contaminated with bacteria and particulate matter. In part I, we prepared dorsal wounds on 15 Sprague-Dawley rats, and 20 mg of Montmorillonite clay soil fraction, a well-known infection-potentiating factor, was placed in each wound. Animals were randomly assigned to one of three treatment groups: ultrasound debridement, soaking, and irrigation. The amount of clay removed from each wound was measured. In part II, 48 Sprague-Dawley rats were given a standard wound and inoculated with a subinfective dose of Staphylococcus aureus bacteria and 10 mg of Montmorillonite clay particles. Each rat was randomly assigned to a debridement technique--soaking, scrubbing, high-pressure irrigation, and ultrasound--and was examined after 7 days for inflammatory responses. Results of part I demonstrated that ultrasound debridement and irrigation remove statistically equal amounts of clay (p < 0.05). In part II, we found that high-pressure irrigation and ultrasound debridement effectively treat contaminated wounds (gross infection, p < 0.05; wound induration, p < 0.0001; bacteria counts, p < 0.002). This study presents ultrasound debridement as effective treatment of contaminated wounds.
Immediate enteral feeding in burn patients is safe and effective.
Recent animal studies indicate that immediate enteral feeding may be beneficial in patients with major burns. Yet, largely because of the fear of complications, immediate enteral feeding is not commonly performed in patients with major burns until after the resuscitation period. The purpose of this study was to evaluate the safety and efficacy of immediate enteral tube feedings in patients with burns larger than 20% of their body surface area. The daily intake of enteral feedings begun immediately (less than 6 hours) after burn was measured during the first 7 days after burn in 106 consecutive patients with a mean +/- SD burn size of 40% +/- 21%. The incidence of complications related to enteral feeding was low; aspiration pneumonia did not occur. Vomiting was the major complication observed and occurred 21 times in 16 patients during the 745 study days (2.8% daily incidence). The mean number of calories absorbed enterally increased daily and met the patient's calculated resting energy expenditure (REE) on day 3 after burn (99% +/- 7% REE). The results of this study indicate that immediate enteral feeding is a safe and effective method of delivering nutritional support to burn victims with major burns.
Risk factors for median sternotomy dehiscence in cardiac surgery.
We retrospectively reviewed several risk factors for median sternotomy dihiscence in our cardiac surgery patients for a recent 18-month period. We studied these factors by univariate and multivariate analysis with respect to sternal dehiscence. Univariate analysis showed several factors to be significant: female sex (P = .03), obesity (P = .002), diabetes (P = .01), and prolonged postoperative ventilation (P = .006). Mammary artery bypass versus saphenous vein bypass only approached significance (14% vs 3%, P = .11). Multivariate analysis showed obesity (P = .002), diabetes (P = .041), and prolonged postoperative ventilation (P = .005) to be important. We conclude that obese diabetic women are at extremely high risk for sternotomy dehiscence, and mammary artery bypass in this high-risk population may be a relative contraindication.
Hypertrophic skin grafts in burned patients: a prospective analysis of variables.
A prospective study of 70 consecutive burned patients, 26 pediatric patients and 44 adults, who had 173 separate anatomic sites grafted, was carried out to determine the incidence of hypertrophic skin grafts after thermal injury. The age, race, postburn day grafted, anatomic site grafted, and nature of the recipient graft bed was recorded. The patients were followed for a minimum of 1 year, at which time the skin grafts were classified as Excellent (E)--skin graft flat and not thickened; Good (G)--less than 5% of skin graft thickened or elevated; Fair (F)--greater than 5% of skin graft thickened or elevated; and Poor (P)--skin graft elevated greater than 2 mm or contracture present. Overall, 55% of the grafted sites were excellent, 18% were good, 13% were fair, and 14% were poor. Pediatric patients had a higher incidence of fair or poor results (50%) than adults (17%) (p less than 0.001), and blacks had poorer (39% F or P) results than whites (12% F or P) (p less than 0.001). The presence of dermal elements in the recipient graft bed was associated with less long-term skin graft scarring than when the grafts were placed on recipient beds without dermal elements (p less than 0.01). Skin grafts that were performed within 14 days of the injury had a lower incidence of F or P results (24%), than grafts performed after 14 days postburn (37%) (p less than 0.03). Based on the results of this prospective study, it is possible to identify and quantitate the relative risk of a burned patient developing a hypertrophic skin graft.
Molecular structure of 5,10-dimethoxybenzo[j]fluoranthene.
The molecular and crystal structure of the synthetic 5,10-dimethoxy derivative of the carcinogen benzo[j]fluoranthene has been determined by direct methods from X-ray diffractometric data and refined to an R index 0.041 over 2788 independent reflections. The benzo ring is inclined at approximately 3 degrees to the almost planar fluoranthene moiety (carbon atoms have r.m.s. deviation of 0.02 A from the carbon-atom plane); the methoxy carbon atoms lie within 0.2 A of the molecular plane. Corresponding bond lengths (e.s.d. 0.004 A for carbon-oxygen and carbon-carbon) and angles lie within 3 sigma for the two independent molecules, with mean dimensions of methoxy groups: C-C = 1.422, C-O = 1.372 A, C-O-C = 117.4 degrees.