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Biomedical subjects

E O'Brien

Publications and source records attributed to E O'Brien.

At least 127 records · Page 7Linked to original sources
PubMed1995

State of the market. A review of ambulatory blood pressure monitoring devices.

The introduction of 24-hour ambulatory blood pressure measurement into clinical practice created a large market for ambulatory blood pressure measurement devices. Forty-three such devices from 31 manufacturers or suppliers are now available to satisfy a market demand that is likely to increase. The aim of this article is to identify the devices available and then to examine critically any validation studies assessing accuracy and performance. Of the 43 devices available 18 have been validated according to the protocols of the Association for the Advancement of Medical Instrumentation (AAMI) or the British Hypertension Society (BHS) in 25 reported studies. In 9 of these studies the protocol was not adhered to, and the results, which are therefore questionable, are noted but not considered further. Fourteen devices were evaluated according to the accuracy criteria of both protocols, and of these 9 fulfilled the requirements. From this review of 43 devices on the market it may be concluded that, at the time of writing, there is published evidence for only 9 devices meeting the generally accepted AAMI and BHS criteria for accuracy and performance; these are the A&D TM-2420 models 6 and 7 and TM-2421, CH-Druck, Nissei ABPM DS-240, Profilomat, QuietTrak, and SpaceLabs SL-90202 and SL-90207.

Blood Pressure Monitoring, Ambulatory↗
PubMed1995

Diurnal blood pressure profile in older patients with isolated systolic hypertension. The SYST-EUR Investigators.

This study describes the diurnal blood pressure (BP) profile and identifies its correlates in older patients with isolated systolic hypertension (ISH). The ambulatory BP readings of 408 patients, aged > or = 60 years, with ISH on clinic measurement, enrolled in the placebo run-in phase of the Syst-Eur Trial were examined. The time-weighted 24 h BP, daytime and night-time BP and the cusum-derived crest and trough BP were computed to express the BP level. The daily alteration between the high and low BP span was estimated from the day-night BP difference, the cusum derived circadian alteration magnitude and plot height, as well as the amplitude of the Fourier curve. The 24 h SBP and DBP tended to be higher in men (150 +/- 15/82 +/- 9 mm Hg) than in women (147 +/- 17/79 +/- 10 mm Hg), but the sex difference was only significant for DBP. In multiple regression analysis, the 24 h SBP increased (P < 0.05) by 3 mm Hg for each 10 year increment in age and was also 10 mm Hg higher (P < 0.001) in smokers than in non-smokers; the 24 h DBP was 2 mm Hg higher (P < 0.05) in men than in women and decreased (P < 0.05) by 1.5 mm Hg for each 10 year increment in age. The day-night difference in SBP increased with 2 mm Hg for each 10 mm Hg increase in the conventional pressure, decreased with 5 mm Hg for each 10 year increment in age and was 6 mm Hg higher in smokers than in non-smokers; the day-night difference in diastolic pressure was 2 mm Hg greater in women than in men. We conclude that the main determinants of the diurnal BP variation in older patients with isolated systolic hypertension were sex, age, smoking habits and the level of pressure on conventional measurement.

Age Distribution↗
PubMed1995

Will mercury manometers soon be obsolete?

After a century of clinical use, the mercury sphygmomanometric technique of blood pressure (BP) measurement is under threat. There are three reasons for this: mercury is likely to be banned from hospital use because of the danger of toxicity, accurate automated devices are now available to replace the mercury sphygmomanometer and with the advent of 24 h ambulatory BP measurement into clinical practice, more reliance is being placed on BP behaviour rather than on casual measurements. The passing of the mercury sphygmomanometer from clinical practice raises two issues that merit deliberation. Without the mercury standard with which to compare measurements generated by algorithmic interpretation of BP, the clinician is dependent on the consistency and accuracy of such algorithms. If the millimetre of mercury is no longer the unit of measurement for BP, it will soon be replaced by the kilopascal thereby introducing, at least temporarily, the potential for uncertainty in clinical judgment.

Blood Pressure↗
PubMed1995

A new audiovisual technique for recording blood pressure in research: the Sphygmocorder.

OBJECTIVE: To devise a method of blood pressure measurement capable of being substituted for the fallible human observer in validation of blood pressure measuring devices. DESIGN: A number of components used to measure blood pressure have been combined innovatively with audiovisual recording technology to produce a system, named the Sphygmocorder, which consists of a mercury sphygmomanometer, an occluding cuff, an inflation source, a stethoscope, a microphone capable of detecting Korotkoff sounds, a camcorder and a display screen. METHODS: To determine the accuracy of the Sphygmocorder against the trained human observer, the Sphygmocorder has been validated in three separate studies in which three devices for self-measurement of blood pressure, the Omron HEM-705CP, the Phillips HP5332 and the Nissei DS-175, were being validated against two trained observers in 85 subjects with a wide range of blood pressure according to the protocol of the British Hypertension Society. RESULTS: The Sphygmocorder was as accurate as at least one of the observers in each of the validation studies and therefore allows replacement of trained observers by the new device. CONCLUSION: The Sphygmocorder, which retains the time-honoured technique of blood pressure measurement with a mercury sphygmomanometer and an auscultating observer, and provides, in addition, objective evidence of the measurement recorded, which can be stored and re-examined, can be used as a substitute for human observers in validation studies of blood pressure-measuring devices.

Blood Pressure Determination↗
PubMed1995

Factors influencing validation of ambulatory blood pressure measuring devices.

With the introduction of 24 h ambulatory blood pressure monitoring into clinical practice a vast market for ambulatory blood pressure monitoring devices has been created. To satisfy this market manufacturers are producing an array of ambulatory blood pressure monitoring devices. There is no obligation on manufacturers to have such devices validated independently, even though two national protocols, one from the British Hypertension Society (BHS) and the other from the Association for the Advancement of Medical Instrumentation (AAMI), call for independent validation and state the means of doing so. However, many factors can influence the validation procedure. They include compliance to the protocol being employed; the accuracy of the standard; establishing precisely the model being validated; the influences of blood pressure level, age and exercise on device accuracy; the provisions necessary for special populations, such as pregnant women, the elderly and children; the influence of oscillometric versus Korotkoff sound detection and electrocardiographic gating on comparative measurements; the assessment of performance as distinct from accuracy; and the relevance of general factors, such as the algorithm being employed and computer compatibility. Forty-three ambulatory blood pressure monitoring devices have been marketed for ambulatory blood pressure measurement and of those only 18 have been validated according to either the BHS or the AAMI protocol. The influence of the factors listed above on the validation studies of those devices will be considered and the relevance of validation procedures to the clinical use of ambulatory blood pressure monitoring devices will be discussed.

Association↗
PubMed1994

Game, set and MRCP.

Explore the source record for details and available documents.

Clinical Competence↗
PubMed1994

Cloning of the glucose 6-phosphate dehydrogenase gene from Plasmodium falciparum.

Glucose 6-phosphate dehydrogenase (G6PD) deficiency is one of the human genetic traits that confer relative resistance against malaria caused by Plasmodium falciparum. It has been previously shown that this organism, during its intraerythrocytic development, produces its own G6PD, which has properties different from those of human G6PD. In order to investigate the role of this enzyme in parasite-host cell interactions, we have isolated the G6PD gene from Plasmodium falciparum as a set of overlapping lambda gt11 clones. By sequence analysis we have found a single open reading frame, uninterrupted by introns, coding for a protein of 910 amino acids, almost twice as long as any previously sequenced G6PD molecule. The P. falciparum G6PD mRNA is 5.1 kb in size and has an exceptionally long 5' untranslated region of some 1000 nucleotides. We have mapped the G6PD gene to chromosome 14. The C-terminal portion of the predicted protein, from amino acid 310-910 (except for an 'insert' of 62 amino acids), has 39% homology to human G6PD, with a number of characteristic, fully conserved peptides. The N-terminal portion of the predicted protein has no homology to G6PD, but it contains a peptide in which 7 out of 12 amino acids are identical to the putative glutathione binding site of human glutathione S-transferase.

Amino Acid Sequence↗