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Biomedical subjects

R W Griffiths

Publications and source records attributed to R W Griffiths.

At least 19 recordsLinked to original sources
PubMed2003

Laboratory models of the thermal evolution of the mantle during rollback subduction.

The subduction of oceanic lithosphere plays a key role in plate tectonics, the thermal evolution of the mantle and recycling processes between Earth's interior and surface. Information on mantle flow, thermal conditions and chemical transport in subduction zones come from the geochemistry of arc volcanoes, seismic images and geodynamic models. The majority of this work considers subduction as a two-dimensional process, assuming limited variability in the direction parallel to the trench. In contrast, observationally based models increasingly appeal to three-dimensional flow associated with trench migration and the sinking of oceanic plates with a translational component of motion (rollback). Here we report results from laboratory experiments that reveal fundamental differences in three-dimensional mantle circulation and temperature structure in response to subduction with and without a rollback component. Without rollback motion, flow in the mantle wedge is sluggish, there is no mass flux around the plate and plate edges heat up faster than plate centres. In contrast, during rollback subduction flow is driven around and beneath the sinking plate, velocities increase within the mantle wedge and are focused towards the centre of the plate, and the surface of the plate heats more along the centreline.

Journal Article↗
PubMed2003

Guidelines.

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Carcinoma, Squamous Cell↗
PubMed2003

Fleur-de-Lys abdominoplasty--a consecutive case series.

Sixty-eight consecutive patients who had undergone Fleur-de-Lys abdominoplasty are described. The mean age was 39 years, (22-62 years) and the mean body mass index (BMI) was 29 kg/m(2) (17-47 kg/m(2)). Forty patients had documented weight loss, mean 39 kg (10-103 kg). The operation duration ranged from 1 h 10 min to 4 h 15 min. The mean mass of tissue resected was 2.4 kg, (0.3-9.1 kg). The overall complication rate was 42/68 (62%) and complications were categorised as early, late, general and aesthetic. Complications were significantly related to patients with a greater age (p=0.0091), increasing BMI (p=0.0039), greater weight (p=0.0014) and greater mass of tissue resected (p=0.0002). There was no significant association between smoking and complications. There was no significant association between previous gastric partitioning surgery and complications. Despite the significant complication rate, a single operation achieved a satisfactory outcome in 82% of patients. Our data reinforce findings from previous studies, which have demonstrated that patients should be required to reduce weight prior to body contouring surgery.

Abdominal Wall↗
PubMed2002

Do plastic surgeons resect basal cell carcinomas too widely? A prospective study comparing surgical and histological margins.

Basal cell carcinoma is a common condition facing the plastic surgeon. When formally excised, a surrounding margin of normal skin is included in an attempt to ensure complete excision. We set out to investigate our excision margins in a prospective study of 100 basal cell carcinomas in 86 patients treated by conventional surgical excision. The edge of each lesion was delineated, an excision margin was drawn, and the closest point was identified and measured. The tumours were excised, and the specimens were examined to determine the closest histological margin. A comparison was made between the marked surgical margins and the margins observed on microscopy. The mean observed surgical margin was 3.0 mm and the mean histological margin was 3.7 mm; 44% of the margins agreed to within 1 mm, 79% to within 2 mm and 92% to within 3 mm. There were four incomplete excisions, all at the lateral margin. There was agreement in the position of the closest margin in 69% of cases. The measured surgical excision margins correlated well with those assessed histologically, as did the position of the closest margin. Given a 3 mm margin, 96% of lesions would have been excised completely. We feel that our current practice represents a satisfactory balance between maintaining a low rate of incomplete excision and minimising the sacrifice of normal skin.

Adult↗
PubMed2002

Audit of clinical and histological prognostic factors in primary invasive squamous cell carcinoma of the skin: assessment in a minimum 5 year follow-up study after conventional excisional surgery.

In an attempt to evaluate the prognostic factors for primary squamous cell carcinoma of the skin treated by conventional surgery, a 6 year (1990-1995) cohort comprising 171 patients was analysed. Of these 171 patients, 157 were confirmed as having been treated for invasive squamous cell carcinoma, of whom 64 (41%) died within 5 years of treatment from causes other than squamous cell carcinoma, and were therefore defined as indeterminate. The remaining 93 patients were determinate patients; 85 lived without recurrence or metastasis for at least 5 years after treatment, and eight died of their disease. Comparing the groups who were alive or had died of disease at 5 year follow-up, the tumour diameter and tumour thickness were significantly greater in the eight patients who died (P = 0.02 and P = 0.0057, respectively) but there were no significant differences between the two groups with regard to age, deep resection margin clearance, lateral epidermal resection margin clearance, lymphocyte response or degree of tumour differentiation. This study defines the 5 year follow-up outcome following conventional surgery for squamous cell carcinoma of the skin, related to histological parameters, which, if routinely reported, would allow valid comparisons to be made between differing primary therapies.

Adult↗
PubMed2000

Patterns of contraction in human full thickness skin grafts.

It is taught that full thickness skin grafts contract minimally in humans. We aimed to examine this assumption. In a prospective study, a scale photograph of each of 54 human full thickness skin grafts was taken at operation once the graft had been inset, but before the application of any tie-over or other dressing. For 50 grafts, a subsequent scale photograph was taken at follow-up (mean 111 days post-operation). The photographs were digitised and the areas of the grafts recorded. Significant area reduction in human full thickness skin grafts was found (P< 0.01, mean area change -38%). Greater contraction was associated with infection than without (P = 0.02, mean area change with infection -48%, without infection -33%). Full thickness skin grafts applied to the peri-orbital area and nose contracted more than those applied to the scalp and temples (P = 0.002). No differences in contraction were found between donor sites, between methods of fixation, between males and females or between those taking no medication and those taking steroids or non-steroidal anti-inflammatory medication. Area change did not correlate with initial graft area, patient age or time to second photograph.

Age Factors↗
PubMed1999

Audit of histologically incompletely excised basal cell carcinomas: recommendations for management by re-excision.

In an audit of 1392 basal cell carcinomas arising in 1165 patients, excised under the care of one consultant in the 10 years from 1988 to 1997, 99 (7%) were reported histologically as incompletely excised. Lateral margins alone were involved in 54 (55%), deep margins in 36 (36%) and both in 9 (9%). Although the policy throughout this period was to re-excise all such lesions, 74/99 (75%) were re-excised (compared with an average re-excision rate of 30% through other published series). For those patients undergoing re-excision, residual tumour was reported histologically in 40/74 (54%). Peri-orbital lesions showed an overall incomplete excision rate of 13% (range 11-17%); however, only 4/16 of re-excisions in this area revealed residual tumour. Many clinicians have traditionally observed patients with incompletely excised basal cell carcinomas. The present study reports the largest series of re-excisions after incomplete excision of basal cell carcinoma, and has revealed that on the balance of probability such re-excisions will reveal residual tumour. Re-excision appears the appropriate course in almost all the anatomical areas studied although, with the exception of the inner canthus, periorbital lesions will have a low probability of residual tumour being identified.

Adolescent↗
PubMed1995

A retrospective analysis of the results of 218 consecutive rhinoplasties.

In a 7-year period, 218 consecutive rhinoplasties were performed within a joint rhinoplasty service comprising a plastic surgeon and an otorhinolaryngologist. Retrospective analysis of these procedures revealed a minor surgical complication rate of 5%, no major complications and requests for revisional surgery in 10% of patients after primary rhinoplasty by the service. However when patients had not had their first operation by our joint service, the revisional operation rate after our first operation was 19%. These results are discussed in relation to other published series. The data generated should enable more precise preoperative patient counselling and act as a useful baseline for subsequent audit of performance. Specifically, patients should know that after rhinoplasty 1 in 10 patients may request revisional surgery. All trainers and trainees should be aware of such data on their own patients in order that standards be set and enhanced with time.

Adolescent↗
PubMed1992

Pharmacokinetics of lignocaine in children after infiltration for cleft palate surgery.

We have studied the pharmacokinetics of lignocaine in children after local infiltration for cleft palate surgery. After induction of anaesthesia, lignocaine 2.5 mg kg-1 with adrenaline 1:200,000 was injected into the palate. Blood samples were collected before and at 2, 5, 10, 15, 20, 30, 60 and 120 min after infiltration. Plasma concentrations of lignocaine were measured by a gas-liquid chromatographic technique. There were no signs of systemic toxicity on routine monitoring of the patients and the peak plasma concentrations were less than the accepted toxic values. Mean half-life was 72.9 (SEM 9.9) min, similar to that found previously in adults and children. However differences in mean clearance (24.6 (2.04) ml kg-1 min-1) and volume of distribution (0.80 (0.07) litre kg-1) were found between this and previous studies.

Anesthesia, General↗
PubMed1990

Plastic surgery outpatient audit: principles and practice of "consultant only" clinics.

The effect of instituting "consultant only" clinics on plastic surgery outpatient activity was to produce a 19% reduction in both clinic sessions and new patient bookings, but a 50% reduction in booked follow-up patients; non-attender rates reduced from 20% to 11% (Northern General Hospital, April 1986-March 1989). Mean clinic attendances reduced from 35 to 26 (Northern General Hospital) and from 33 to 27 (Barnsley District Hospital)--26% and 18%, respectively. Analysis of new referrals to such clinics in the 6 months January-June 1989 showed 41% of patients came from general practitioners, although 80% of "aesthetic" conditions came from this source. 31% of referrals were for malignancy, 51/72 (70%) being basal cell carcinomas. Malignancies waited on average 4 weeks, benign conditions 15 weeks, and "aesthetic" conditions 28 weeks from referral to consultation. Such clinic management has dramatically reduced follow-up episodes, but regulation of new patient attendances is associated with appreciable waiting times for non-malignant conditions. To reduce such waiting times and pursue a "consultant only" clinic policy nationally requires many more consultants.

Adolescent↗
PubMed1989

Skin malignancy and the reconstructive plastic surgeon.

Skin malignancy represents at least 25% of the plastic surgeon's workload. The commonest tumour, the basal cell carcinoma, usually arises in the skin of elderly patients who are frequently managed by surgery under local anaesthetic, often as outpatients. The recurrent basal cell carcinoma poses a difficult problem regardless of the primary therapy. Skin repair with direct closure or skin grafts is usually simple, but skin flaps will be needed when bone, cartilage or major neurovascular structures are exposed, or where tissue vascularity has been reduced by irradiation fibrosis. Squamous cell carcinomas of lip, ear and hand may recur as lymph node metastases despite clinical and histological clearance. Malignant melanoma continues to present as advanced disease (thick tumours) in this country, and this largely dictates prognosis, since tumour thickness is recognised as the single most important dominant prognostic variable. Incisional biopsy compromises histological microstaging and should be avoided. Indirect evidence from narrow margin excision of invasive head and neck cutaneous melanomas suggests no detriment, and narrow margin excision of melanomas is increasingly being practised.

Basal Cell Carcinoma↗
PubMed1988

Outpatient clinics.

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Appointments and Schedules↗
PubMed1988

The bolus tie-over "pressure" dressing in the management of full thickness skin grafts. Is it necessary?

It has been taught that the bolus tie-over "pressure" dressing is essential for the successful "take" of full thickness skin grafts. This was tested in a prospective randomised trial in which 40 full thickness grafts were either managed with the conventional bolus dressing, or alternatively with quilting sutures and no dressing. Whether under local or general anaesthesia there was only one total graft failure from haematoma (tie-over bolus group) and one partial graft failure from haematoma (quilted group). Sixty-five per cent. of all grafts were performed by junior surgical trainees. The bolus tie-over "pressure" dressing does not appear essential for full thickness skin graft survival in the areas of the head and neck studied.

Aged↗
PubMed1988

Relative risk: mortality probability and plastic surgery.

Recent publications indicate an increasing interest in the description and assessment of risks related to medical and surgical treatment. The law may come to require fuller disclosure of therapeutic risks than was formerly the case. Against this background the mortality risks of plastic surgery procedures are considered in relation to other well documented mortality probabilities. The possible implications for clinical practice and "informed consent" are discussed.

Adolescent↗