Robert Martin

Noninvasive diagnosis of renal artery stenosis by ultrasonic duplex scanning.

We retrospectively studied the results of duplex scanning for evaluation of renal artery disease in 158 patients. Satisfactory examinations were achieved in 144 patients (90%). Arteriograms were available for 43 renal arteries. We used the ratio of the peak velocities in the renal artery and the aorta (RAR) to separate nonstenotic arteries (less than 60% diameter reduction) from stenotic arteries (greater than 60% diameter reduction). With an RAR of greater than 3.5 to indicate stenotic lesions, duplex scanning had a sensitivity of 91% (20 of 22 diseased arteries correctly identified) and specificity of 95% (20 of 21 normal or insignificantly diseased arteries correctly identified). One of four occluded arteries was incorrectly interpreted as patent because of misidentification of a collateral vessel. Prospective studies will be necessary to validate this test and establish other criteria for a more detailed classification of renal artery stenosis. The ratio of the end-diastolic to peak systolic velocities in the renal artery (EDR) tended to decrease with increasing serum creatinine levels, presumably because renal vascular resistance increases with end-stage parenchymal disease. EDR may prove useful in the detection of advanced parenchymal disease before renal artery revascularization is attempted.

Suppression of experimental abdominal aortic aneurysms by systemic treatment with a hydroxamate-based matrix metalloproteinase inhibitor (RS 132908)

BACKGROUND Abdominal aortic aneurysms (AAAs) are associated with chronic inflammation, disruption of medial elastin, and increased local production of elastolytic matrix metalloproteinases (MMPs). The purpose of this study was to investigate how treatment with a hydroxamate-based MMP antagonist (RS 132908) might affect the development of experimental AAAs. METHODS Male Wistar rats underwent intraluminal perfusion of the abdominal aorta with 50 units of porcine pancreatic elastase followed by treatment for 14 days with RS 132908 (100 mg/kg/day subcutaneously; n = 8) or with vehicle alone (n = 6). The external aortic diameter (AD) was measured in millimeters before elastase perfusion and at death, with AAA defined as an increase in AD (DeltaAD) of at least 100%. Aortic wall elastin and collagen concentrations were measured with assays for desmosine and hydroxyproline, and fixed aortic tissues were examined by light microscopy. RESULTS AAAs developed in all vehicle-treated rats, with a mean AD (+/- SE) that increased from 1.60 +/- 0.03 mm before perfusion to 5.98 +/- 1.02 mm on day 14 (DeltaAD = 276.4 +/- 67.7%). AAAs developed in only five of eight animals (62.5%) after MMP inhibition, with a mean AD that increased from 1.56 +/- 0.05 mm to 3.59 +/- 0.34 mm (DeltaAD = 128.1 +/- 18.7%; P <.05, vs vehicle). The overall inhibition of aortic dilatation attributable to RS 132908 was 53.6 +/- 6.8%. Aortic wall desmosine fell by 85.4% in the vehicle-treated rats (1210.6 +/- 87.8 pmol/sample to 176.7 +/- 33.4 pmol/sample; P <.05) but only by 65.6% in the animals treated with RS 312908 (416.2 +/- 120.5 pmol/sample). In contrast, hydroxyproline was not significantly affected by either elastase perfusion or drug treatment. Microscopic examination revealed the preservation of pericellular elastin and a greater degree of fibrocollagenous wall thickening after MMP inhibition, with no detectable difference in the extent of inflammation. CONCLUSIONS Systemic MMP inhibition suppresses aneurysmal dilatation in the elastase-induced rodent model of AAA. Consistent with its direct inhibitory effect on various MMPs, RS 132908 promotes the preservation of aortic elastin and appears to enhance a profibrotic response within the aortic wall. Hydroxamate-based MMP antagonists may therefore be useful in the development of pharmacologic approaches to the suppression of AAAs.

Use of hemodynamic parameters in the diagnosis of mesenteric insufficiency

To evaluate the hemodynamic characteristics of the normal mesenteric circulation, five parameters of the velocity waveforms were measured in 15 normal subjects in the celiac and superior mesenteric arteries (SMA) in the pre- and postprandial periods. It was noted that changes in celiac artery flow after eating was minimal, indicating that this vessels major supply function is not to the gut. SMA parameters showing the most significant and consistent changes after a meal were the diastolic reverse flow and diastolic forward flow (DFF). Four patients referred with symptoms of intestinal angina underwent scanning and subsequent angiography of their mesenteric circulation. All four exhibited loss of reverse flow in the SMA. The change in DFF in the SMA was statistically significant (p = 0.01). Change in peak systolic velocity in the celiac artery was marginally significant (p = 0.05). Angiography revealed that three patients had greater than 90% stenosis of both vessels. The fourth patient had a 90% celiac artery and 65% SMA stenosis. The technique described offers the first noninvasive means of identifying mesenteric insufficiency. It is an effective screening method for a disease entity difficult to verify without selective arteriography. The use of velocity waveform parameters giving good discrimination between normal subjects and those with stenoses of the visceral arteries should reduce both the incidence of missed diagnosis and unnecessary angiography.

Pathophysiology of venous claudication

Patients with chronic iliofemoral venous obstruction may develop severe thigh pain and a sensation of tightness with vigorous exercise (venous claudication). The discomfort requires 15 to 20 minutes to subside. In the seven patients studied the venous capacitance (VC) and venous outflow (VO) are lower than those of the unaffected limb even at rest. With exercise to the point of pain, the VO was unchanged but the VC decreased even further. The problem appears to rest with the venous collaterals, which have a high and fixed resistance. Because of this high outflow resistance, venous volume increases to near maximum during exercise. With this rise in venous volume, the amount the VC can increase during the period immediately following exercise is further reduced.

Diastolic flow as a predictor of arterial stenosis

With a pulsed Doppler imaging system, it is now possible to interrogate sites from the aorta to the popliteal trifurcation. To determine which velocity parameters could be correlated with the degree of disease as determined by angiography, 34 arterial stenoses identified by scanning were also evaluated by contrast arteriography and classified in 10% increments. The angiographic readings were blinded with respect to the scan results. Four hand-measured parameters from velocity waveforms obtained at the site of stenosis were correlated with the angiogram--peak systolic velocity, systolic rise time, diastolic reverse velocity, and diastolic reverse flow time. When diastolic reverse flow was absent, diastolic forward flow was recorded. To describe diastolic flow along a continuum, diastolic reverse velocity was ascribed a positive value and diastolic forward velocity was ascribed a negative value. A systolic velocity gradient (peak velocity/rise time) was also calculated. The relationship between the angiographic categories and the measured parameters was evaluated with the Jonkheere-Terpstra trend test. A trend was determined with diastolic flow (diastolic reverse flow or diastolic flow velocity) that was significant (p less than 0.01). The linear regression was calculated (y = 40.8 + [-5.6X]), and correlation coefficient was obtained (r = 0.76) that was statistically significant (p less than 0.01). The method enables mapping and calculation of arterial stenoses by noninvasive means. This can be expected to obviate the need for diagnostic angiograms in certain and select cases in which angioplasty can be expected to be beneficial. It also affords a convenient quantitative means of following lesions over time.

Global Laboratory Systems Development: Needs and Approaches

Functional laboratory systems are a key component of country health care systems. Laboratory strengthening in resource-limited countries has been supported by disease-specific vertical programs that have focused on laboratory methods, procedures, and supplies for a country program, and providing training in performing tests. A health systems focus requires attention to regulations, management of national systems, national approaches to quality assurance, and education of laboratory scientists. An immediate focus of resources on the components required for a functioning system and continued technical support will enable countries to assume responsibility for their country-specific needs and improve their capability to address international responsibilities.

Continuing professional development training needs of medical laboratory personnel in Botswana

BackgroundLaboratory professionals are expected to maintain their knowledge on the most recent advances in laboratory testing and continuing professional development (CPD) programs can address this expectation. In developing countries, accessing CPD programs is a major challenge for laboratory personnel, partly due to their limited availability. An assessment was conducted among clinical laboratory workforce in Botswana to identify and prioritize CPD training needs as well as preferred modes of CPD delivery.MethodsA self-administered questionnaire was disseminated to medical laboratory scientists and technicians registered with the Botswana Health Professions Council. Questions were organized into domains of competency related to (i) quality management systems, (ii) technical competence, (iii) laboratory management, leadership, and coaching, and (iv) pathophysiology, data interpretation, and research. Participants were asked to rank their self-perceived training needs using a 3-point scale in order of importance (most, moderate, and least). Furthermore, participants were asked to select any three preferences for delivery formats for the CPD.ResultsOut of 350 questionnaires that were distributed, 275 were completed and returned giving an overall response rate of 79%. The most frequently selected topics for training in rank order according to key themes were (mean, range) (i) quality management systems, most important (79%, 74–84%); (ii) pathophysiology, data interpretation, and research (68%, 52–78%); (iii) technical competence (65%, 44–73%); and (iv) laboratory management, leadership, and coaching (60%, 37–77%). The top three topics selected by the participants were (i) quality systems essentials for medical laboratory, (ii) implementing a quality management system, and (iii) techniques to identify and control sources of error in laboratory procedures. The top three preferred CPD delivery modes, in rank order, were training workshops, hands-on workshops, and internet-based learning. Journal clubs at the workplace was the least preferred method of delivery of CPD credits.ConclusionsCPD programs to be developed should focus on topics that address quality management systems, case studies, competence assessment, and customer care. The findings from this survey can also inform medical laboratory pre-service education curriculum.

Making great strides in medical laboratory quality : editorial

Whilst the observation of blood and urine as a commentary of illness and disease can be traced back to Hippocrates as early as 300 BC, the true roots and foundations of the modern medical laboratory as a vital investigation process to better understand pathology and diagnosis were established in the late-19th and early-20th centuries. Modern day laboratory tests have become the cornerstone for objective data collection to assist, affirm and document diagnoses rather than depending on anecdotal and subjective opinion. Use of highly-crafted optical lenses made microscopic examination of urine, sputum, blood and spinal fluid achievable. Microbiology techniques for blood and sputum culture made the diagnosis of tuberculosis, diphtheria and typhoid both possible and documentable. Examination for bilirubinaemia and abnormal glucose levels also became feasible. The first hospital laboratories were established in London (Guys Hospital) and Baltimore (Johns Hopkins Hospital) and, by the early 20th century, laboratories began to become a permanent part of the infrastructure of hospitals.

Effect of On-Site Support on Laboratory Practice for Human Immunodeficiency Virus, Tuberculosis, and Malaria Testing.

OBJECTIVES To evaluate the effect of on-site support in improving human immunodeficiency virus (HIV) rapid testing, tuberculosis (TB) sputum microscopy, and malaria microscopy among laboratory staff in a low-resource setting. METHODS This cluster randomized trial was conducted at 36 health facilities in Uganda. From April to December 2010, laboratory staff at 18 facilities participated in monthly on-site visits, and 18 served as control facilities. After intervention, 128 laboratory staff were observed performing 587 laboratory tests across three diseases: HIV rapid testing, TB sputum microscopy, and malaria microscopy. Outcomes were the proportion of laboratory procedures correctly completed for the three laboratory tests. RESULTS Laboratory staff in the intervention arm performed significantly better than the control arm in correctly completing laboratory procedures for all three laboratory tests, with an adjusted relative risk (95% confidence interval) of 1.18 (1.10-1.26) for HIV rapid testing, 1.29 (1.21-1.40) for TB sputum microscopy, and 1.19 (1.11-1.27) for malaria microscopy. CONCLUSIONS On-site support significantly improved laboratory practices in conducting HIV rapid testing, TB sputum microscopy, and malaria microscopy. It could be an effective method for improving laboratory practice, without taking limited laboratory staff away from health facilities for training.

An innovative educational approach to professional development of medical laboratory scientists in Botswana

Purpose To address the shortage of laboratory scientists in Botswana, an innovative, one-year academic bridging program was initiated at the University of Botswana, to advance diploma-holding laboratory technicians towards becoming laboratory scientists holding Bachelor’s degrees. An evaluation was conducted, which described the outcomes of the program and the lessons learned from this novel approach to meeting human resource needs. Methods This was a cross-sectional, mixed-methods evaluation. Qualitative interviews were conducted with graduates of the Bachelor of Science (BSc) Medical Laboratory Sciences (MLS) bridging program, along with the graduates’ current supervisors, and key informants who were involved in program development or implementation. The quantitative data collected included a written questionnaire, completed by program graduates, with a retrospective pre-test/post-test survey of graduates’ confidence, in terms of key laboratory competencies. Results The BSc MLS bridging program produced thirty-three laboratory scientists over 3 years. There was a significant increase in confidence among graduates, for specified competencies, after the program (P<0.05). Graduates reported acquiring new skills and, often, accepting new responsibilities at their former workplace, particularly in relationship to leadership and management. Five graduates enrolled in advanced degree programs. Most graduates assumed increased responsibility. However, only two graduates were promoted after completing the training program. The lessons learned include: the importance of stakeholder involvement, the need for data to identify local needs, financial sustainability, catering for the needs of adult learners, and ensuring a technically challenging work environment, conducive to the application of skills learned during training. Conclusion A strong public health and clinical laboratory system is essential for the rapid detection and control of emerging health threats, and for patient care. However, there is a need to adequately prepare laboratory human resources, to ensure efficient and effective laboratory services. Advancement of laboratory technicians towards becoming laboratory scientists, through a bridging program, can provide the necessary skills within a short time.