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Biomedical subjects

C J Martin

Publications and source records attributed to C J Martin.

At least 55 records · Page 3Linked to original sources
PubMed1999

High pressures are generated at the tip of laparoscopic graspers.

BACKGROUND: Despite its importance the interface between tissue and instrument is poorly understood. METHODS: A thin film pressure transducer was deployed between the jaws of eight different laparoscopic instruments and a simulated tissue to study the forces generated at the tip of laparoscopic graspers and the effect of a change in angle of tissue tension at the interface between tissue and laparoscopic grasper. RESULTS: Pressure was concentrated at the tip of the instrument. Localized pressures increased on average from 210 kPa to 650 kPa as the angle of grasp was increased from 0 to 135 degrees. There was a wide variation between instruments with some exhibiting increases in tip pressure of a factor of eight as the angle was increased. CONCLUSION: High pressures are generated at the tip of laparoscopic graspers. Pressures increase as the angle of incidence of the grasper in relation to the tissue increases. The changes in pressure with change in angle are independent of load and handle pressure.

Humans↗
PubMed1999

Transhiatal versus Ivor-Lewis oesophagectomy: is there a difference?

INTRODUCTION: Curative oesophageal resection for carcinoma may be carried out by either the transhiatal or the Ivor-Lewis transthoracic technique. The aims of this study were to compare the morbidity, 30-day mortality and long-term survival of the two techniques in the treatment of oesophageal carcinoma and to provide data to calculate the sample sizes for a prospective randomized trial. METHODS: Results from 44 series published between January 1986 and December 1996 were reviewed. Thirty-three papers reported results on 2675 patients having transhiatal (THO) and 29 papers reported results on 2808 patients having Ivor-Lewis oesophagectomy (ILO). RESULTS: The two groups were comparable in terms of age, sex and stage of the disease. There was no apparent difference in postoperative morbidity between the two groups with respect to respiratory complications (24% for THO, 25% for ILO), cardiovascular complications (12.4% for THO, 10.5% for ILO), wound infection (8.8% for THO, 6.2% for ILO) and chylothorax (2.1% for THO, 3.4% for ILO). The transhiatal group appeared to have a higher incidence of anastomotic leaks (16% for THO, 10% for ILO), anastomotic strictures (28% for THO, 16% for ILO) and recurrent laryngeal nerve injuries (11.2% for THO, 4.8% for ILO). The 30-day mortality was 6.3% for transhiatal and 9.5% for Ivor-Lewis oesophagectomy. Overall long-term survival at 5 years was similar (24% for THO, 26% for ILO). CONCLUSIONS: The surgical approach to oesophagectomy was not an important determinant of morbidity and long-term survival in patients with oesophageal carcinoma. Transhiatal oesophagectomy was associated with a higher incidence of anastomotic complications and recurrent laryngeal nerve injury. Ivor-Lewis oesophagectomy had a higher mortality. In order to demonstrate a significant difference in morbidity or long-term survival between the two techniques 3100 patients would be required in each arm of a prospective randomized trial.

Aged↗
PubMed1999

The importance of radiometer angular response for ultraviolet phototherapy dosimetry.

The influence of the angular response of radiometer probes on measurements of irradiance in ultraviolet phototherapy has been studied. Irradiance measurements were made using nine ultraviolet (UV) radiometers employed by phototherapy centres in Scotland and Northern Ireland, and compared with measurements made using two spectroradiometers. The light sources used were UVB TL01 fluorescent lamps, arranged in different geometries. Irradiances within TL01 whole body treatment cabinets were assessed based on a comparison with one of the spectroradiometers. The results show variations of 50% in cabinet irradiance measurements made by different radiometers, even when they were calibrated using the same source geometry and spectroradiometer. Differences in radiometer probe design and construction lead to an under- or over-response at angles of incidence greater than zero. Angular responses of different probes were assessed using banks of fluorescent lamps. The differences found are large enough to account for the variations in measurements of cabinet irradiance. The variations in irradiance measurements are significant in terms of planning and monitoring patient exposure during TL01 phototherapy. Accurate dosimetry can only be achieved if radiometer probes have a good cosine response and recommendations are made for better calibration techniques.

Radiometry↗
PubMed1999

Case report; effective community palliation of intractable malignant ascites with a permanently implanted abdominal drain.

A patient with intractable malignant ascites from metastatic tabular breast carcinoma underwent insertion of a Tenckhoff catheter in July 1997. Seventeen months later the patient continues to have excellent symptomatic relief, without complications, by self-drainage of ascites at home. Tenckhoff catheter can be useful in the management of intractable malignant ascites.

Journal Article↗
PubMed1999

Reductions in finger doses for radiopharmaceutical dispensing afforded by a syringe shield and an automatic dose dispenser.

A gamma extremity monitoring system (GEMS) has been used to measure finger doses during radio-nuclide dispensing procedures. GEMS uses a small semi-conductor probe that can be attached to a finger from which a continuous read-out can be obtained that is related to dose rate. The pattern of dose accumulation can be analysed to allow doses received from individual operations within a procedure to be evaluated. GEMS has been used to compare the radiation dose reduction afforded by a syringe shield and an automatic dose dispenser. Dispensing procedures were simulated using 10% of the activity normally administered in order to avoid problems with detector saturation. Results show that the syringe shield and the automatic dose dispenser reduced finger doses by more than a factor of 10 for the procedures tested. The disadvantages of the automatic dispenser tested were a failure to transfer activity in 10% of cases and a longer time taken for the dispensing process. GEMS has the potential to facilitate greater optimization of finger doses through analysis of finger dose patterns.

Dispensatories as Topic↗
PubMed1998

Scaphoid malunion. The significance of rotational malalignment.

Three patients with painful malunions of the scaphoid and significant loss of active wrist extension were treated with an opening wedge multiplanar osteotomy that corrected flexion, ulnar deviation, and pronatory rotational malalignment of the distal fragment. After a minimum follow-up of 4 years, all three patients were satisfied with the procedure and were pain-free. The preoperative range of wrist motion had improved, and they had returned to their preoperative occupations.

Adult↗
PubMed1998

Sunbeds in current use in Scotland: a survey of their output and patterns of use.

Spectral irradiances of 100 commercially available sunbeds in current use have been measured. Ultraviolet (UV) A and UVB doses from sunbed use have been calculated and compared with doses likely to be received from solar radiation. The majority of sunbeds use UVA fluorescent tubes for irradiating the body and filtered metal halide lamps, which have a higher proportion of UVA1, for the face. The average minimum erythemal dose per session is 0.80, but irradiances for particular models varied by a factor of two to three primarily because of decline in lamp output with age. The UVA dose from a session on a sunbed is similar to that which might be received from 20 to 30 min sunbathing at a Mediterranean resort or 1 h on a sunny day in Glasgow, while UVB doses are 20-25% of this level. Responses from 200 current users of the sunbeds indicate that 38% had skin types 1 and 2, that 17% had more than 100 annual sunbed sessions and that 35% rarely or never used the goggles provided.

Adult↗
PubMed1998

A study of chest radiography with mobile X-ray units.

A survey of radiographic technique and estimated entrance surface dose has been carried out for 364 chest radiographs performed with mobile X-ray equipment in the Intensive Therapy Unit (ITU) and 30 wards at Aberdeen Royal Infirmary. Data for these two types of location were compared, as were those for two film/screen systems used on the wards. Image quality assessments were made on sets of radiographs for two patients. Entrance skin doses for chest radiographs performed in the ITU were 50% greater than on the wards with the same film/screen system. The main technique difference was the use of shorter focus-to-skin distances (FSDs) in ITU. Doses with the Kodak Insight system were 20% higher than those using Du Pont Quanta III in similar locations. No correlation was found between image quality and entrance surface dose (ESD). Results from the survey were used to recommend exposure factors for shorter FSDs. A follow-up study revealed a 35-45% reduction in ESD for Kodak Insight and a 20% reduction for Quanta III.

Follow-Up Studies↗
PubMed1998

Protocol for measurement of patient entrance surface dose rates for fluoroscopic X-ray equipment.

While patient entrance surface dose rate is an important indicator of dose performance for fluoroscopic units, there has been no standardized approach to measuring this. Since results are strongly dependent on the type of phantom used and the relative positions of the X-ray tube, intensifier and phantom, comparisons of the performance for different units are difficult to make. This document sets out a protocol for making these measurements using a standard phantom and standard configurations for different types of X-ray unit Values of dose rates which might be expected are given.

Clinical Protocols↗
PubMed1997

Interpretation of the trace metal analysis profile for patients occupationally exposed to metals.

Trace element profile analysis detects and quantifies the presence of several metals simultaneously at low concentrations in the body. In occupational medicine, it may be used to monitor exposure or to evaluate suspected toxicity. Clinical interpretation is often difficult because, with the exception of lead and possibly cadmium, there is little firm information on toxicity thresholds. For these tests, the reference ranges typically reflect low levels of exposure in the general population and it is expected that workers handling metals in occupations such as welding and industries such as steelmaking will have higher levels. Interpretation requires some knowledge of the toxicokinetics of the metal of interest and the preferred medium for analysis for each: serum, whole blood or urine (preferably 24-hour collection). Trends are often more informative than concentrations at one time. Trace element values are reported together with a reference range which must be distinguished from the normal range of other clinical tests. As a practical matter, the greatest interpretation problems tend to be found with manganese because serum levels have a poor correlation with both recent exposure and neurological symptoms. Molybdenum and vanadium are often found to be elevated among workers exposed to metals who show no evidence of clinical illness. Interpretation of the trace element profile analysis overall when an elevation occurs generally requires close attention to the pattern of elevation, clinical context, absolute and relative magnitude of the elevation and knowledge of the exposure history.

Data Interpretation, Statistical↗
PubMed1997

Application of a gamma extremity monitoring system in a radiopharmaceutical dispensary.

A new gamma extremity monitoring system (GEMS) was used to assess finger doses of staff working in a hospital radionuclide dispensary. The system is designed to give a continuous readout of dose rate from a small probe which may be attached to a finger. It allows the contributions to radiation dose to the fingers from different parts of a procedure to be measured for the first time and the detailed pattern of radiation exposure to be determined. The dose reduction benefits of small changes in procedure and the use of syringe shields were easily demonstrated after monitoring staff for a few sessions using GEMS, which would not have been possible using thermoluminescent or other integrating dosemeters. GEMS was calibrated against 99Tc(m), 241Am, 137Cs and 131I. The main disadvantage of the system is that the response of the detector increases significantly at lower radiation energies, with that at 60 keV being approximately 70 times the response at 662 keV. In addition, the response of the current detector is nonlinear and saturates around 7000 counts s(-1), which corresponds to a dose rate of 2200 microGy h(-1) for 99Tc(m). Despite these drawbacks, GEMS can play a significant part in the analysis of finger dose patterns and assist in dose reduction.

Americium↗
PubMed1997

Short segment Barrett's oesophagus: prevalence, diagnosis and associations.

BACKGROUND: Prevalence of short segment Barrett's (SSB) oesophagus, defined as the absence of macroscopic Barrett's but histologically identifiable intestinal metaplasia, has been reported to be 18% based on haematoxylin and eosin (H&E) staining. AIMS: To define the prevalence of SSB oesophagus using H&E and alcian blue staining and to determine whether SSB oesophagus is associated with inflammation at the gastro-oesophageal junction (GOJ). SUBJECTS: Consecutive patients (n = 158) presenting for endoscopy completed a structured interview. METHODS: Two biopsy specimens taken from the GOJ were stained with H&E, alcian blue and Giemsa. A third specimen was obtained from the distal oesophagus. Intestinal metaplasia was diagnosed if goblet cells were definitely identified by two independent observers. RESULTS: SSB oesophagus was present in 46 (prevalence 36%, 95% confidence interval (CI) 28.5-43.5) using alcian blue staining. If H&E had been the sole staining method used, 50% cases of intestinal metaplasia would have been overlooked. There were no cases of intestinal metaplasia identified by H&E but missed by alcian blue staining. Logistic regression analysis identified age (odds ratio (OR) per decade 1.03, 95% CI 1.01-1.06), histological oesophagitis (OR 3.2, 95% CI 1.4-7.2) and inflammation at the gastrooesophageal junction (OR 5.9, 95% CI 2.2-15.6) as independent risk factors for SSB oesophagus. CONCLUSION: Unrecognised SSB oesophagus is highly prevalent in patients presenting for diagnostic upper endoscopy if alcian blue staining is applied.

Adult↗
PubMed1997

Damp housing and asthma: a case-control study.

BACKGROUND: Several epidemiological studies have reported a higher prevalence of respiratory symptoms in subjects living in damp housing, but links with specific respiratory diseases such as asthma have not been satisfactorily established. METHODS: One hundred and two subjects with physician diagnosed asthma and 196 age and sex matched controls were interviewed; 222 (75%) then agreed to have their dwelling surveyed for dampness. The prevalence of both self-reported and observed dampness in the homes of the asthmatic subjects and controls were compared. Both asthma and the severity of the dampness were quantified so that the possibility of a dose-response relationship could be investigated. RESULTS: Asthmatic subjects reported dampness in their current (odds ratio (OR) 1.92, 95% confidence interval (CI) 1.18 to 3.12) and previous (OR 2.11, 95% CI 1.29 to 3.47) dwellings more frequently than control subjects. The surveyor confirmed dampness in 58 of 90 (64%) dwellings of asthmatic subjects compared with 54 of 132 (41%) dwellings of control subjects (OR 2.62, 95% CI 1.50 to 4.55). This association persisted after controlling for socioeconomic and other confounding variables (adjusted OR 3.03, 95% CI 1.65 to 5.57). The severity of asthma was found to correlate statistically with measures of total dampness (r = 0.30, p = 0.006) and mould growth (r = 0.23, p = 0.035) in the dwelling. Patients living in homes with confirmed areas of dampness had greater evidence of airflow obstruction than those living in dry homes (mean difference in forced expiratory volume in one second (FEV1) 10.6%, 95% CI 1.0 to 20.3). CONCLUSIONS: Asthma is associated with living in damp housing and there appears to be a dose-response relationship. Action to improve damp housing conditions may therefore favourably influence asthma morbidity.

Adolescent↗
PubMed1997

Markets, Medicare, and making do: business strategies after national health care reform.

This essay examines the role of business health care purchasers in keeping market solutions at the center of the health system. One might assume that employers would have a clear ideological preference for market solutions, but big business managers are ambivalent about market interventions at both the firm and public policy levels. Although currently enthusiastic about market-oriented managed care, large employers have been periodically disappointed by firm-level market experiments during the past two decades. They viewed with skepticism the Republican proposal to apply private-sector market cures to the public Medicare and Medicaid, fearing that the proposals would accelerate cost-shifting to private business payers. Big business objections have been muted, however, by the organizational weakness so vividly illustrated during the national health reform debate.

Commerce↗
PubMed1997

Orbital pseudotumor: case report and overview.

BACKGROUND: The most common cause of a sudden onset of painful proptosis with diplopia in an otherwise healthy adult is orbital pseudotumor. However, there are other conditions that mimic this presentation and must be ruled out with laboratory testing and imaging studies. CASE REPORT: A 41-year-old Hawaiian man sought treatment for an acute, progressive, painful, left ophthalmoplegia without exophthalmos. During the next week, a loss of accommodation and associated pupillary reaction, decreased visual acuity, color vision deficits, and a paracentral scotoma developed. CT and MRI revealed a mass in the orbital apex. All systemic findings were negative, and high-dose systemic steroid therapy was initiated. Symptoms resolved within hours of the first dose, and signs were completely absent 1 month later. Follow-up MRI revealed complete absence of the previously noted mass. CONCLUSION: This is an atypical case of orbital pseudotumor, since there was no exophthalmos. It was diagnosed by clinical presentation, laboratory and imaging studies, and response to therapy.

Adult↗