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Biomedical subjects

A J McKay

Publications and source records attributed to A J McKay.

At least 19 recordsLinked to original sources
PubMed2006

Should pre-operative troponin be a standard requirement in patients undergoing major lower extremity amputation?

OBJECTIVES: The objective of this study was to ascertain the benefit of routine pre-operative cardiac troponin I (cTnI) measurement in patients undergoing major lower extremity amputation for critical limb ischaemia. DESIGN: This was a prospective, blinded observational study. METHODS: All patients scheduled for lower extremity amputation, without evidence of unstable coronary artery disease were recruited prospectively over a period of 1 year. In addition to routine pre-operative evaluation, a blood sample was taken for measurement of serum cTnI. Post-operative screening was conducted for cardiac events with patients followed up to 6 weeks. RESULTS: Ten of the 44 patients included suffered a non-fatal myocardial infarction or died from a cardiac cause post-operatively. A rise in pre-operative cTnI was associated with a very poor outcome (two cardiac deaths and one post-operative myocardial infarction) and was the only significant predictor of post-operative cardiac events. CONCLUSION: Routine pre-operative cTnI measurement may be of use to identify patients at high risk of cardiac complication who would benefit from optimization of cardiac status or in whom surgery could be deferred.

Adult↗
PubMed2004

Ten-year experience of carbon dioxide laser ablation as treatment for cutaneous recurrence of malignant melanoma.

BACKGROUND: Cutaneous recurrence of malignant melanoma is distressing for the patient, can be difficult to palliate and is resistant to treatment by conventional methods. Experience with carbon dioxide laser ablation was reviewed to determine the initial efficacy, time to recurrence, number of treatments required and length of palliation achieved. METHODS: Using a departmental database and case notes, a review was carried out of all patients undergoing laser ablation in the authors' unit between September 1992 August 2002. RESULTS: Forty-two patients received 105 (mean 2.5) treatments. The median time to recurrence was 5.2 (range 1.2-72.0) months. Twenty-three patients were still alive, with a median time from first laser ablation of 5.4 (range 0.5-10.0) years. Nineteen patients had died, a median of 0.8 (range 0.1-5.3) years after the first ablation. Ten of the 23 patients were disease-free for more than 1 year. No limbs were amputated because of failure to control disease. CONCLUSION: Laser ablation is a practical and useful method of palliating recurrent cutaneous malignant melanoma.

Aged↗
PubMed2003

Revalidation--are we fixing a system that wasn't broken?

In 10 years, the medical profession in the U.K. has moved from a loose system of self regulation, through reluctant and patchy compliance with recorded continuing medical education (CME) to statutory obligations for 5-yearly revalidation which will control the issuing of a licence to practise for all doctors. The profession initially viewed these changes with dismissive cynicism, but the new rules are now being viewed with trepidation and paranoia. Royal Colleges can still play a central role in the development of the Revalidation process and must work together to develop appraisal as a meaningful tool to be used for the benefit of patient and doctor.

Education, Medical, Continuing↗
PubMed2000

Revalidation: the catalyst for change in continuing professional development?

Remarkably, only five years ago, hospital specialists were under no formal obligation to record participation in Continuing Medical Education (CME). No one seriously doubted that such education took place, but the system had never been challenged. In recent years, and with apparently ever increasing pace, all this is changing. Traditional, didactic, lecture based teaching of undergraduates is slowly vanishing from many undergraduate curricula. Postgraduate hospital training has been brought into line with Europe so that, within 7 years of full registration, it is theoretically possible to become a consultant. The Royal Colleges were charged with developing and monitoring a structured system of CME and chose to use the "points" system of which there was experience elsewhere. Around 70% of surgeons returned their annual CME forms and almost all met the agreed minimum points total. As a meaningful educational exercise which impacted favourably on patient care the points system was impossible to defend vigorously, and was ignored by an important minority. More recently still, our entire profession has been exposed to regular and fundamental criticism. There was a real risk that we would lose the right to self regulation. The GMC has now announced that every doctor will be required to undergo a process of appraisal that will lead to revalidation, allowing the doctor to remain on the national register. A full consultative process is now in place, with the Royal Colleges being required to implement a new system of annual review which will allow profiling of every surgical practice. While it is possible react to these changes with a combination of resentment and paranoia, the profession should grasp this opportunity for change. The sensible introduction of personal portfolios should allow us to maintain and improve standards of care, and allow us to demonstrate these standards to our peers, our employers and our patients. We may yet look back on clinical governance and revalidation as the catalysts which brought about constructive change to a potentially complacent profession.

Clinical Competence↗
PubMed1997

Intraoperative identification of sentinel lymph node in patients with malignant melanoma.

We report our experience with the technique of lymphatic mapping using patent blue V dye in patients with limb malignant melanoma. The technique is based on the hypothesis that embolic metastases occur along lymphatic channels to a 'sentinel' lymph node: the draining lymph node nearest the site of the primary malignant melanoma. Patent blue V dye (0.5-1.0 ml) is injected intradermally around the site of the melanoma. Immediately the groin or axilla is opened and the blue lymphatic channels followed to the sentinel node. The node is removed and examined by both haematoxylin and eosin (H&E) and immunohistochemical staining. We have carried out this technique in 35 patients, all of whom had 'clinically assessed' stage I disease. In all 35 patients, sentinel nodes were identified, and nine were found to contain unsuspected micrometastases. Our initial evaluation of intraoperative lymphatic mapping is very promising. The technique is practicable and easy to master. If 25% of patients with cutaneous malignant melanoma who are clinically stage I have nodal disease, this has great importance not only for staging and treatment but also for all future therapeutic trials.

Adult↗
PubMed1996

A single centre's 10 year experience with isolated limb perfusion in the treatment of recurrent malignant melanoma of the limb.

The aim of this study was to assess whether isolated limb perfusion can be performed safely and whether it offers improved disease-free survival for patients with limb malignant melanoma. Between August 1983 and July 1993, 103 patients (78 female, 25 male) with recurrent limb melanoma were treated by isolated limb perfusion (ILP) in Glasgow, U.K. The mean age of the patients was 62 years; 95 had leg recurrence, 8 had arm recurrence. The mean time from original diagnosis to ILP was 48 months (range 1-290). 102 iliac, 5 femoral, 7 popliteal and 8 axillary perfusions were performed. All patients had stage II (local recurrence within 3 cm of primary site) or stage III (regional metastases; tissues excluding nodes, nodes or combination) disease according to the MD Anderson Cancer Centre Staging System. At a mean follow-up of 30.7 months, 68 patients had died of recurrent disease (mean time to death 22.5 months). The 2 and 5 year survival of the group was 50 and 26%, respectively and disease-free survival was 23 and 12%, respectively. At first perfusion, 76% of patients showed complete response and 23% showed partial response. With repeat perfusion, 47% showed complete response and 53% had partial response. In conclusion, ILP is safe and has an acceptable morbidity. It achieves highly satisfactory local disease control but long-term survival is the exception.

Adult↗
PubMed1996

A comparison of dosimetric methods in isolated limb perfusion with melphalan for malignant melanoma of the lower extremity.

The three dosimetric schedules currently used in isolated limb perfusion with melphalan for malignant melanoma of the lower limb were compared in a series of 51 patients. The doses prescribed by each of the three methods (based on total body weight (TBW), limb tissue volume (LTV) and total blood volume in the perfusion circuit (TBV)) were calculated for all patients and were then compared using Wilcoxon's signed-rank test. This revealed that the method based on TBV consistently prescribed much lower doses of drug than either of the other two methods. Pharmacokinetic profiles of melphalan obtained by HPLC analysis of blood samples during the procedure also showed that the method did not reliably predict the concentration of melphalan achieved in the perfused limb. The dosimetric schedule based on LTV prescribed slightly higher doses than that based on TBW. However, the technique is more difficult to practise due to the problems of measuring the limb volume by immersion. We conclude that the dosimetric schedule based on TBW is the most appropriate by virtue of its simplicity, the high doses of melphalan which it prescribes, and the well-controlled toxicity which it produces.

Antineoplastic Agents, Alkylating↗
PubMed1996

The Scottish Royal Colleges: a prospective survey of continuing medical education undertaken by their examiners.

OBJECTIVE: To measure the amount and nature of Continuing Medical Education (CME) activity undertaken by the examiners of the three Scottish Royal Colleges. The data obtained to be compared with recommendations for formal CME participation published by the medical Royal Colleges and Faculties. DESIGN: All examiners in active clinical practice prospectively surveyed over a 12 month period by completing a monthly return from a specially designed loose-leaf diary. RESULTS: 75% of the examiners who submitted all 12 monthly diary pages completed at least 100 hours CME during the year while 95% achieved 50 hours or more. This time was distributed approximately equally between hospital-based activities and activities for which study leave might have been taken. Although the mean total number of hours of CME undertaken by consultants based in district general hospitals was also over 100 hours in the year, this was significantly lower than the figure for teaching hospital consultants. The type of CME activity was described as general (16%), specialty (49%) and subspecialty (35%). The examiners surveyed found that specialist society and international specialist meetings were perceived to be the most valuable of those attended. CONCLUSIONS: The current recommendations for implementing formal CME systems for consultants are in line with the current activity levels of this group and should safeguard existing educational activity rather than impose new standards. This study suggests that the profession should not be unduly anxious about the introduction of a structured CME system although it is likely that some form of obligatory scheme will be required to achieve a more uniform response.

Education, Medical, Continuing↗
PubMed1995

Single-centre prospective study of isolated limb perfusion with melphalan in the treatment of subungual malignant melanoma.

Subungual melanoma is rare and experience in treating this condition with isolated limb perfusion is limited. Between 1985 and 1990, 24 patients were treated by digital amputation and isolated limb perfusion with melphalan and mild hyperthermia. The disease was staged according to the M.D. Anderson classification: stage I (17 patients), stage IIIA (one), stage IIIB (two) and stage IIIAB (four). Thirteen lesions were on the foot and 11 on the hand. Seven patients have developed locoregional recurrence. The estimated overall 2- and 5-year probabilities of survival were 77 and 46 per cent respectively, while for disease-free survival the rates were 58 and 51 per cent. When these results were compared retrospectively with those in 111 patients treated by amputation alone, no significant difference in survival was demonstrated. This experience suggests that isolated limb perfusion with melphalan and mild hyperthermia confers no additional survival benefit over appropriate surgery.

Adult↗
PubMed1995

Carbon dioxide laser ablation as an alternative treatment for cutaneous metastases from malignant melanoma.

Surgical excision of cutaneous malignant melanoma metastases is practical only when the number of lesions is small. In some patients isolated limb perfusion is not possible or fails to achieve control, and carbon dioxide laser ablation is then an alternative treatment. Between September 1992 and September 1994, 19 patients aged 45-94 years were treated with carbon dioxide laser. Two patients had received no previous limb perfusion, while the remaining 17 had up to three previous perfusions. The number of lesions per patient ranged from three to 40 nodules. A Sharplan 1030 portable carbon dioxide laser was used, which generates a beam wavelength of 10.6 microns and has a maximum power output of 80 W. All procedures were carried out under general anaesthesia. Each lesion was destroyed with a focused laser beam of 10-20 W with a spot size of 0.5-1.0 mm. At a mean follow-up of 15 months, five patients have died from the disease. Among the 14 survivors, eight have had no limb recurrence of the disease, three have had one further treatment and three a further two treatments to control cutaneous metastases at new sites. Early experience suggests that carbon dioxide laser ablation of cutaneous metastases is an effective palliative treatment after failed isolated limb perfusion, and there may be a group of patients in whom laser ablation should be the initial treatment of choice.

Aged↗
PubMed1993

Elective lymph node dissection in the management of malignant melanoma.

The surgical management of regional nodes in patients with cancer has been controversial for many years. This paper reviews the role of elective lymph node dissection in the management of malignant melanoma. The evidence for and against elective lymphadenectomy is discussed and a policy of therapeutic, rather than elective, lymph node excision recommended.

Contraindications↗
PubMed1993

K infusion corrects thick ascending limb Cl reabsorption in K-depleted rats by an aldosterone-independent mechanism.

Others have provided evidence that thick ascending limb (TAL) NaCl reabsorption is aldosterone dependent in adrenalectomized animals. In rats fed a K-free diet, plasma K concentration ([K]) is reduced and plasma aldosterone concentration [Aldo] is decreased. Because aldosterone release is regulated by extracellular fluid (ECF) [K], the purpose of the present study was to determine whether aldosterone deficiency mediates inhibition of TAL NaCl transport in K-depleted rats (K-Dep). Cl reabsorption was measured in functionally isolated loop segments microperfused in vivo (22 nl/min) using a modified perfusate that minimizes proximal nephron reabsorption. The results of our studies show that the defect in TAL Cl reabsorption in K-Dep rats is quantitatively significant and can be rapidly reversed by the acute systemic infusion of K. However, acute administration of aldosterone, in the presence of sustained K-Dep, failed to reverse the impairment in TAL Cl reabsorption in K-Dep rats. Furthermore, acute infusion of K, in the presence of an aldosterone antagonist, in K-Dep rats rapidly corrected the defect in TAL Cl reabsorption. Additional studies showed that despite normalization of ECF [K] by acute K infusion in K-Dep rats, plasma [Aldo] failed to increase. In contrast, acute infusion of KCl in control rats increased plasma [Aldo] by 46%, but Cl reabsorption was unchanged. In summary, these results provide conclusive evidence that the correction of defective TAL Cl reabsorption in response to the acute administration of K in K-Dep rats occurs via an aldosterone-independent mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1993

Endogenous prostaglandin E2 mediates inhibition of rat thick ascending limb Cl reabsorption in chronic hypercalcemia.

The hypothesis that endogenous PGE2 mediates defective thick ascending limb (TAL) Cl reabsorption (percent delivered load: FRCl%) in rats with vitamin D-induced chronic hypercalcemia (HC) was tested by measuring FRCl% in loop segments microperfused in vivo in HC and control rats treated acutely with indomethacin (Indo) or its vehicle, and obtaining the corresponding outer medullary [PGE2]. Microperfusion conditions were developed in which FRCl% was exclusively furosemide sensitive. To determine the cellular mechanism, tubules were perfused acutely with forskolin (FSK), cAMP, or the protein kinase C inhibitor staurosporine (SSP). Outer medullary [PGE2] in HC rats was 9 to 10 times greater than control and could be normalized by Indo. FRCl% was 20% lower in HC rats infused with vehicle, and Indo, FSK, and cAMP returned FRCl% to normal despite sustained HC. Indo or FSK had no effect on FRCl% in control rats and Indo did not prevent inhibition of FRCl% by luminal PGE2 (1 microM). Luminal SSP (10(-7), 10(-8) M) in HC did not return FRCl% to control values. We conclude that impaired TAL FRCl% in HC occurs at a pre-cAMP site and is due to endogenous PGE2 and not to HC.

Alkaloids↗
PubMed1992

Melphalan concentration and distribution in the tissues of tumour-bearing limbs treated by isolated limb perfusion.

Levels of melphalan (L-phenylalanine mustard) were measured in the tissues of tumour-bearing limbs treated by isolated limb perfusion (ILP). 41 samples of melanoma tissue, normal fat and skin were excised from 15 patients during ILP. A high performance liquid chromatography assay was used to measure melphalan concentrations. Levels of melphalan were higher in tumour than in fat (P < 0.01, Wilcoxon signed-ranks test), and not significantly different from levels in adjacent skin. In 2 cases there was significant regional toxicity in the treated limb, but this was not related to the levels of melphalan measured in the tissues of the limb. It is encouraging that the concentrations of melphalan which were achieved in large necrotic nodules by ILP were similar to those in well-perfused normal skin.

Adipose Tissue↗
PubMed1992

The pharmacokinetic advantages of isolated limb perfusion with melphalan for malignant melanoma.

We describe melphalan pharmacokinetics in 26 patients treated by isolated limb perfusion (ILP). Group A (n = 11) were treated with a bolus of melphalan (1.5 mg kg-1), and in a phase I study the dose was increased to 1.75 mg kg-1. The higher dose was given as a bolus to Group B (n = 9), and by divided dose to Group C (n = 6). Using high performance liquid chromatography (HPLC) the concentrations of melphalan in the arterial and venous perfusate (during ILP) and in the systemic circulation (during and after ILP) were measured. Areas under the concentration time curves for perfusate (AUCa, AUCv) and systemic (AUCs) data were calculated. In all three groups the peak concentrations of melphalan were much higher in the perfusate than in the systemic circulation. The pharmacokinetic advantages of ILP can be quantified by the ratio of AUCa/AUCs, median value 37.8 (2.1-131). AUCa and AUCv were both significantly greater in Group B than in Group A (P values less than 0.01, Mann-Whitney). In Groups B and C acceptable 'toxic' reactions occurred but were not simply related to melphalan levels. Our phase I study has allowed us to increase the dose of melphalan to 1.75 mg kg-1, but we found no pharmacokinetic advantage from divided dose administration.

Arteries↗
PubMed1992

Peripheral arterial thrombosis related to commercial airline flights: another manifestation of the economy class syndrome.

Venous thromboembolism is a well recognised complication of air travel, particularly on long haul flights. This has been attributed to relative immobility in cramped surroundings and to dehydration secondary to alcohol consumption and low cabin humidity. Under these conditions thrombosis at other sites would be expected, and indeed myocardial ischaemia is the commonest emergency in commercial flights. Peripheral arterial thrombosis, however, is not reported, even in comprehensive reviews of flying related medical emergencies. We report on three patients who developed acute lower limb ischaemia following long haul air flights.

Aerospace Medicine↗