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Biomedical subjects

D W Ryan

Publications and source records attributed to D W Ryan.

At least 37 records · Page 2Linked to original sources
PubMed1993

Accuracy of interface pressure measurement systems.

Interface pressure measurement is needed to assess beds designed to prevent pressure sores, so it is therefore important to establish the accuracy of interface pressure measuring systems. In this study, the Talley SA500 pressure evaluator (with 28 mm and 100 mm sensor pads), the DIPE (with 100 mm sensor pad), and a water-filled bladder system (with 0.1 ml and 0.3 ml water) were assessed. Measurement errors were evaluated using a loading system with pressures up to 7.4 kPa (55 mm Hg) in steps of 0.9 kPa (6.9 mm Hg). All systems tested over-measured interface pressure, the error being approximately linearly proportional to the loading pressure. The repeatability for a given system was approximately constant. The mean error (+/- SD) (%) and repeatability (kPa) for the systems were: 28 mm Talley 12 +/- 1%, +/- 0.07 kPa; 100 mm Talley 15 +/- 1%, +/- 0.07 kPa; DIPE 27 +/- 3%, +/- 0.12 kPa; 0.1 ml water bladder 17 +/- 1%, +/- 0.13 kPa; 0.3 ml water bladder 26 +/- 3%, +/- 0.07 kPa. Different interfaces affected accuracy markedly, and repeatability was affected when an inhomogeneous interface was used. The study shows that the errors associated with interface pressure measurement systems can be substantial, and can vary from one system to another.

Beds↗
PubMed1993

Air-fluidized beds and their ability to distribute interface pressures generated between the subject and the bed surface.

Pressures were measured under five anatomical sites prone to pressures sores for ten subjects, supine and sitting on two different air-fluidized beds. The beds were the Clinitron (trademark, SSI) and the Fluidair Plus (trademark, KCI Mediscus). Mean supine pressures were less than 4 kPa under four sites. The average supine buttock pressure was 2.65 kPa. This increased to 3.71 kPa upon sitting up, though pressures did not rise above the accepted capillary closing pressure, on either bed. Low interface pressures at these sites were due to good moulding between subject and bed. Heel pressures averaging 7.08 kPa, were a factor of 2.67 times greater than buttock pressure, and were higher than expected considering the depth the heels sunk to in both beds. This exceeded the accepted capillary closing pressure and was attributed to covering sheets preventing true floatation at the heels.

Adult↗
PubMed1992

Blood conservation.

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Blood Loss, Surgical↗
PubMed1991

Minitracheotomy Seldinger--assessment of a new technique.

A multicentre, prospective study of 26 patients was undertaken for the assessment of insertion of minitracheotomy tubes by the Seldinger technique. The technique of insertion is described. There were two misplacements, three blockages of the inserting Tuohy needle with fat, and six cases of difficulty in passing the minitracheotomy tube.

Anesthesia, Local↗
PubMed1991

Minitracheotomy.

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Critical Care↗
PubMed1990

Minitracheotomy.

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Drainage↗
PubMed1990

Nitrogen sparing and the catabolic hormones in patients nursed at an elevated ambient temperature following major surgery.

Fasted patients managed at an elevated ambient temperature following major surgery have reduced nitrogen excretion and body protein catabolism. To investigate the mechanism behind this three 24 h urine collections were made in 16 patients nursed for 48 h following aortobifemoral surgery on a Clinitron fluidized bed at 32 degrees C and analysed for total urinary nitrogen, cortisol and catecholamine excretion. Results were compared with a similar group of patients nursed throughout on a standard ITU bed at 22 degrees C. Patients managed at the elevated ambient temperature showed a significant reduction in the cumulative total urinary nitrogen (20.73 g +/- 6.42 v 28.95 g +/- 6.44; mean +/- S.D.; p less than 0.002) and cortisol excretion (1238 microg +/- 436 v 2197 microg +/- 844; mean +/- S.D.; p less than 0.001). Catecholamine excretion was also reduced but failed to achieve significance. There were significant correlations between cumulative total nitrogen excretion and both cortisol (r = +0.414; p = 0.02; n = 32) and noradrenaline (r = +0.369; p = 0.05; n = 32). These results confirm that the beneficial effect of an elevated ambient temperature on postoperative protein metabolism is brought about through a reduction in metabolic stress.

Aged↗
PubMed1990

Disseminated zygomycosis and systemic lupus erythematosus.

A young woman with long-standing systemic lupus erythematosus and rheumatic fever presented with deteriorating renal function. She had severe gastritis treated with cimetidine and received methylprednisolone when her blood cultures were repeatedly negative. She developed spontaneous bruising and bleeding from venepuncture sites, leading to clotting studies and a diagnosis of thrombotic thrombocytopenic purpura. At post-mortem, extensive evidence of disseminated zygomycosis was found. The likely portal of entry was the gastric route.

Adult↗
PubMed1989

A study of contact pressure points in specialised beds.

Pressure was measured at seven body points liable to develop pressure sores, in four commonly available beds. A small water-filled sensor attached to a transducer and measuring system was used, and the limitations of this system are discussed. The investigation was undertaken in female volunteers lying supine in each of the beds. The results show that compared with the standard, hard mattress normally used in the intensive care bed all the specialised beds have some beneficial effect. The water bed produces an even distribution of body weight but some elevation in pressures, notably in the sacrum and heel regions. The fluidized bed was the most consistent but the low air loss bed also provided safe pressures and has the advantage of greater postural flexibility.

Beds↗