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Biomedical subjects

J McTavish

Publications and source records attributed to J McTavish.

8 recordsLinked to original sources
PubMed2000

Normal saline wound dressing--is it really normal?

Gauze swabs soaked in normal saline are frequently used as dressing on open wounds. Their exact mechanism of action is not known. This study was designed to assess the hypothesis that normal saline dressings act in part as an osmotic dressing. Ten patients had skin ulcers (n = 10) dressed with normal saline soaked sponges. Acting as controls (n = 10) identical sponges were placed upon intact skin. The sponge fluid osmolarity and electrolyte concentrations were serially assayed to test our hypothesis. In the control group, the osmolarity, sodium and chloride concentrations increased with time as a result of evaporation, altering it from an isotonic to a hypertonic dressing. However, in the ulcer group, the osmolarity, sodium and chloride concentrations in the sponge fluid remained relatively isotonic with time. This result is statistically significant (P< 0.05). We postulate that, as a result of evaporation, the sponge dressing increases its tonicity. This draws fluid from the wound into the dressing so that a dynamic equilibrium occurs and the sponge dressing regains isotonicity. The dressing remains functional provided that the wound fluid is absorbed freely from the wound. This process is terminated when either the dressing completely absorbs the wound fluid or the dressing dries out. The latter often occurs prematurely in a contaminated wound or in a wound where exudate forms a non-permeable barrier which prevents osmosis and allows the remaining water in the dressing to evaporate completely. This correlates with the observation in clinical practice that for maximum efficacy the dressing should be changed regularly.

Chlorides↗
PubMed2000

Does the sheep mandible relapse following lengthening by distraction osteogenesis?

AIM: Distraction osteogenesis is a technique used to lengthen the shortened mandible. However, the long term stability of the distracted mandibular bone is not known. The aim of this study was to assess if the sheep mandible relapses following lengthening, and to assess the quality of distracted bone up to 1 year post lengthening. METHODS: Twenty-four sheep had bilateral external mandibular distractors applied, with three sheep as controls. Titanium marker screws were positioned both proximal and distal to the distraction zone in all sheep. Following a 5 day latency period, the interdental gap was distracted 1 mm/day for 20 days, with a subsequent 20 day consolidation period. Ante-mortem serial X-rays were used to assess for relapse by measuring the distance between the screws. The animals were sacrificed at either 3, 6, 9 or 12 months post-distraction. At post mortem, the distance between the screws was re-measured. The distracted bone was assessed mechanically and histologically. RESULTS: The mean mandibular lengthening obtained was 13.2 mm. There was no relapse of the mandible over 12 months. The distracted bone had attained the strength and stiffness of undistracted bone by 6 months post-distraction (p < 0.05). Histological evaluation revealed significant amounts of lamellar bone by 6 months post-distraction. CONCLUSIONS: No relapse occurred for 12 months post distraction lengthening. The bone formed following distraction was stable and of good quality. These findings lend support to the use of distraction osteogenesis in clinical practice.

Analysis of Variance↗
PubMed1997

The gunner with the silver mask: observations on the management of severe maxillo-facial lesions over the last 160 years.

We would like to present a case of severe maxillo-facial trauma occurring over 150 years ago. The case involves a French artillery gunner, Monsieur Alphonse Louis, who received shrapnel injuries from an exploding shell at the Siege of Antwerp in 1832. He sustained near fatal injuries. The fact that he survived is probably due to his rapid evacuation from the battle site, as the French did not like to leave their wounded lying in 'no man's land', prompt surgery and subsequent expert medical and nursing care. M. Louis' maxillo-facial injuries included loss of the entire mandible. As a consequence, the patient had a grotesque appearance and was unable to eat or talk properly. At this time the surgeons of the day had no specialist knowledge of how to reconstruct the lower jaw. Where specialist knowledge or facilities were absent, then as now, improvisation was called for. A silversmith was duly approached and asked to construct a mask to act as a replacement for the deficient lower face. We describe here what an excellent cosmetic and functional result the mask gave, and how it led to the patient being successfully rehabilitated. Almost a century later, during the First World War, pioneering work by Major Harold (later Sir Harold) Gillies and his colleagues led to the first attempts at anatomical mandibular reconstruction. His patients, like M. Louis, were soldiers injured in battle. We will describe his techniques and compare them with how this problem is approached in the modern era, although most reconstructive surgery to the maxillo-facial region these days follows the removal of comparably extensive areas of soft tissue and bone as a result of invasive tumour.

Europe↗
PubMed1996

Determinants of success and failure of EMLA.

Although EMLA is known to be an effective topical anesthetic, its rate of success is unknown. Indeed, researchers have suggested that EMLA may fail with young and apprehensive children. Therefore, the objectives of this study were to assess EMLA's rate of success as well as factors which predict success. A double-blind, placebo-controlled design was utilized. The sample included 258 children and adolescents aged 5-18 years who were having venipuncture or intravenous (i.v.) cannulation. After having their anxiety assessed, subjects were randomly assigned to have EMLA or placebo applied over the procedure site for 90 min. The visual analogue scale was used to assess pain caused by removal of the semi-permeable dressing and by the procedure. Other information that was collected included: duration of drug application, interval between drug removal and procedure, skin changes at bandage and drug sites and rated difficulty of the procedure. EMLA was successful 84% of the time for venipuncture and 51% of the time for i.v. cannulation. Factors which predicted success of EMLA included type of procedure, duration of drug application and anxiety. EMLA was less successful for i.v. cannulation compared to venipuncture even with duration of drug application controlled. Those who had a poor outcome were more anxious than those with a good outcome. Age of child was not a factor. Strategies for improving efficient use of EMLA were recommended.

Administration, Topical↗
PubMed1995

Clinical presentation and pathophysiology of meatal stenosis following circumcision.

OBJECTIVE: To describe the clinical presentation and pathophysiology of meatal stenosis occurring after circumcision. PATIENTS AND METHODS: The clinical presentation and operative findings are reported in 12 children who presented with meatal stenosis over a period of 3 years. RESULTS: The cardinal symptoms of meatal stenosis were penile pain at the initiation of micturition (12 of 12), narrow, high velocity stream (8 of 12) and the need to sit or stand back from the toilet bowl to urinate (6 of 12). Following surgical correction with meatotomy there was no recurrence of stenosis after a mean follow-up of 13 months. Traumatic meatitis of the unprotected post-circumcision urethral meatus and/or meatal ischaemia following damage to the frenular artery at circumcision are suggested as possible causes of meatal stenosis. CONCLUSION: Preservation of the frenular artery at circumcision, or the use of an alternative procedure (preputial plasty), may be advisable when foreskin surgery is required, to avoid meatal stenosis after circumcision.

Child↗
PubMed1995

Prolonged cancer death. A family affair.

The frequency with which families have to deal with cancer death is increasing as the population ages. The prevalence of some cancers in younger people is also increasing. In this article the authors focus on helping families deal with the anticipated cancer death of a family member. The article includes a definition of those groups of people who form families in the 1990s and examines dimensions along which families vary such as belief systems. We discuss the needs of families when a family member has a terminal cancer diagnosis and outline coping strategies that are seen in families and ways in which nurses and other health care professionals can facilitate adaptive coping.

Adaptation, Psychological↗
PubMed1977

Histocompatibility antigens and myocardial infarction.

HLA typing was carried out in 50 Edinburgh men aged 45 years or under who had experienced a myocardial infarction and in 96 healthy 40-year-old men radomly selected from the same community. No significant differences in antigen frequencies were found, and our results therefore fail to support the hypothesis suggesting an association between HLA-B8 and haplotype A1-B8 with ischemic heart disease.

HLA Antigens↗