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Biomedical subjects

S Ryan

Publications and source records attributed to S Ryan.

At least 109 records · Page 6Linked to original sources
PubMed1991

Relationship between arthroscopic evidence of cartilage damage and radiographic evidence of joint space narrowing in early osteoarthritis of the knee.

We examined the relationship between articular cartilage degeneration, as visualized arthroscopically, and joint space narrowing (JSN) in standing anteroposterior knee radiographs of 161 patients with chronic knee pain. The majority of these patients had radiographic findings of mild osteoarthritis. Twenty-five (33%) of the 76 patients in the series whose radiographs showed tibiofemoral JSN had grossly normal articular cartilage in both tibiofemoral compartments at arthroscopy (false-positive). The specificity of medial JSN for the presence of medial compartment articular cartilage degeneration was 0.61, i.e., only 61% of patients with normal (grade 0) medial compartment cartilage had a normal medial joint space. Of 22 patients with greater than 50% medial JSN, 9 (41%) had normal articular cartilage in the medial compartment at arthroscopy. Of 6 patients with greater than 50% lateral JSN, 3 (50%) had normal lateral compartment articular cartilage at arthroscopy. Among 36 patients with greater than 25% JSN who had neither medial nor lateral compartment articular cartilage degeneration, JSN was associated with articular cartilage degeneration in the patellofemoral compartment in 8 (22%), with meniscus degeneration in 18 (50%), and with both in 8 (22%). Thus, in these patients with chronic knee pain, radiographic evidence of JSN in the tibiofemoral compartment did not permit confident prediction of the status of the articular cartilage.

Adolescent↗
PubMed1991

Solid phase extraction of oxcarbazepine and its metabolites from plasma for analysis by high performance liquid chromatography.

A rapid, sensitive and simple-to-operate high performance liquid chromatographic method for the simulataneous determination of oxcarbazepine, 10-hydroxycarbazepine and 10,11-dihydro-10,11-trans-dihydroxy-carbamazepine in plasma is described. The drug and its metabolites were extracted from plasma using commercially available reversed phase octadecylsilane bonded-silica columns (Bond Elut C18, 1 mL capacity). Chromatographic separation of oxcarbazepine and its metabolites was achieved using a mobile phase consisting of acetonitrile/methanol/water (13:25:62 by volume) at a flow rate of 1.2 mL/min in conjunction with a Waters Associates Nova-Pak C18 column. The analytical column, in Radial-Pak cartridge form, was used in combination with a LiChrospher 5 microns C18 guard column. By measuring the UV absorbance at 214 nm, plasma levels in the region of 50-100 ng/mL for the drug and its metabolites can be detected with only 100 microL of plasma. The method has been applied to pharmacokinetic studies of oxcarbazepine and its metabolites in children with epilepsy; preliminary pharmacokinetic findings in two patients at steady-state are presented.

Anticonvulsants↗
PubMed1991

Otoacoustic emission tests in neonatal screening programmes.

Otoacoustic emission (OAE) testing has many characteristics which suit it for use as an objective neonatal auditory screener. The most important of these is the speed with which it can be performed. This feature alone opens up the possibility of much more general neonatal screening programmes. We here review the important considerations in applying otoacoustic testing to neonatal screening applications, and discuss the future role of OAE testing. Practical considerations in applying the technique are illustrated by examples and experiences drawn from a pilot whole-population neonatal screening project. Unselected screening takes us into unexplored territory. Test failure rate will inevitably far exceed the real incidence of hearing impairment. The concept of rapid whole-population neonatal OAE screening techniques as an additional risk factor detector rather than a definitive hearing test seems more appropriate to the low incidence of hearing impairment in the population and to the ethical problems surrounding early and erroneous diagnosis of hearing impairment.

Cochlea↗
PubMed1991

The influence of contralateral acoustic stimulation on click-evoked otoacoustic emissions in humans.

Contralateral acoustic stimulation has the effect of reducing the amplitude and shifting the phase of click-evoked OAEs. This effect is thought to be mediated via the medial efferent system and, therefore, the presence of this effect could be used to test the integrity of the neural pathway from one cochlea to the other. With a clinical application in mind, a technique for demonstrating the influence of contralateral acoustic stimulation on click-evoked OAEs was designed to overcome fluctuations in patient and environmental noise. The results of this test on three normal subjects and a patient with a posterior fossa lesion are described.

Acoustic Stimulation↗
PubMed1991

Hyperbaric oxygen therapy: treatment for spinal cord decompression sickness.

Spinal cord injury (SCI) may result from decompression sickness associated with sport and commercial diving. Decompression sickness is caused by the formation of gas bubbles in the vessels and tissues secondary to a reduction in ambient pressure. A complete or incomplete spinal cord injury may result from decompression sickness. Recompression and hyperbaric oxygen therapy is the primary treatment. The use of hyperbaric oxygen therapy (HBO) as a treatment for these injuries can greatly influence the patient's outcome. Early intervention in a recompression chamber may result in complete recovery. If treatment is delayed however, the prognosis for recovery is poor.

Decompression Sickness↗
PubMed1991

A functional classification of respiratory compromise in spinal cord injury.

Spinal cord injury (SCI) patients have unique care needs, particularly related to the respiratory system. Respiratory problems now comprise a major cause of death in the acute and chronic phases of SCI, especially among quadriplegics. Previous literature has analyzed respiratory muscle dysfunction in SCI according to neurologic levels of injury (Alvarez, Peterson & Lunsford, 1981; McMichan, Michel & Westbrook, 1980). In general, the higher the level of injury, the greater the respiratory compromise and need for ventilatory assistance. Although level of injury is significant, it cannot be used as the sole determinant of respiratory compromise. For example, a 25 year old C4 quadriplegic with an intact diaphragm might have less respiratory impairment than a 60 year old C6 quadriplegic with CHF and a history of COPD. A new classification of SCI patients according to amount of respiratory compromise was developed by our team at the Spinal Cord Injury Unit at the Palo Alto VA Medical Center. The patient is scored in three categories: 1) level of injury; 2) completeness of injury; and 3) associating factors, i.e. age, preinjury chronic lung disease. The purpose of this grouping is to better predict the amount of ventilatory impairment in SCI patients. Used during the initial assessment, patients at high risk for impairment could be determined and optimal respiratory care initiated. This classification can also be used as a clinical nursing tool. Using this scoring system, the nurse could anticipate the patient's respiratory needs, i.e. suctioning, chest physiotherapy, oxygen, hydration, nutritional support and teaching of patient and family in order to comprehensively plan and implement care.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Development of an integrated wheelchair tray system for augmentative communication.

This paper describes the development of a wheelchair tray system for persons with physical disabilities who require an augmentative communication system. The tray system offers advantages over existing systems by providing a convenient anterior/posterior tilt feature, a means for stowing the tray when not in use, and a method of accommodating communication systems and powered wheelchair controls. Caregivers of seven subjects fitted with the prototype system assessed its performance through the completion of questionnaires provided at the end of 6-week field trials. The technical performance of the systems was also monitored. The prototype system was favorably received by six participants. Several recommendations are made to further increase consumer acceptance of the final tray design.

Adolescent↗
PubMed1990

A guide to the effective use of otoacoustic emissions.

Otoacoustic emission test instruments are now entering routine audiological practice. Two general classes of technique are in use in laboratory work--those employing spectrum analysers to observe the continuous generation of OAEs, both stimulated or unstimulated, and those using transient stimulation and waveform averaging to extract a delayed OAE or "cochlear echo" waveform from ear canal sound. Both methods have particular advantages in clinical applications. The transient OAE type of method has proved very effective in screening applications, particularly in neonates. It is possible to perform noninvasive screening acoustic cochleography in about a minute. The technique is also useful for characterizing cochlear mechanical status prior to long term monitoring. Achieving routinely reliable OAE test performance in clinical and screening applications under nonideal conditions makes special demands on the instrumental design and the response evaluation procedures. The essential requirements are reviewed and discussed in a general and specific context. We have tried to meet these requirements in a transient evoked otoacoustic emission system (the ILO88) which we designed to operate with a personal computer. We report on our design of probe, and our use of evaluation procedures for probe fit, and response quality. Signal processing methods have been developed to reject noncochlear acoustic responses, and to optimise the rejection of patient noise. Examples of its clinical use, and the practical problems typically encountered are given here.

Adult↗
PubMed1990

Ultrasound as part of a 1-day gastroenterology clinic: advantages and problems.

Ultrasound was introduced into a 1-day gastroenterology clinic so that clinical assessment, endoscopy and ultrasound could be performed as appropriate in a single hospital visit. The findings in 602 patients are reported. A total of 256 (43%) patients underwent ultrasound, 35% of which showed positive findings including cholelithiasis in 12% and tumours in 7%. This system of referral for ultrasound is very convenient for patients and their general practitioner and is less costly than traditional referral methods. It is, however, time-consuming for the radiologist.

Adolescent↗
PubMed1990

Rehabilitation engineering in pediatrics.

Applications of science and technology in the (re)habilitation of children and young adults can have dramatic, positive influences on their lives. Prosthetics, orthotics, mobility, postural support and seating, communication and education are responsibilities of the rehabilitation engineer. A holistic approach in meeting individual needs for technology is essential. The concerted rehabilitation engineering programme at The Hugh MacMillan Rehabilitation Centre supports service programmes with relevant research and development work.

Biomedical Engineering↗
PubMed1989

Posterior penetrating injury in the rabbit eye: effect of blood and ferrous ions.

The effects of intravitreal injections of blood or ferrous chloride solutions on experimental posterior penetrating eye injury in the rabbit are described. An 8-mm standard posterior penetrating wound, without additional manipulation, healed without retinal detachment or membrane formation. Injection into the vitreous cavity of blood or ferrous chloride solution in addition to the wound resulted in fibroblastic proliferation with membrane formation. A critical amount of blood or iron solution was associated with marked traction and traction retinal detachment. Severe inflammation in association with the development of thick intravitreal membranes was also observed in eyes receiving the ferrous chloride solutions, the extent of which was related to the severity of the retinal detachment. These results show that iron is an important stimulus to inflammation and to intravitreal fibroblastic proliferation in rabbit eyes with posterior penetrating eye injuries.

Animals↗
PubMed1989

Electrophysiological discrimination between retinal and optic nerve disorders.

In this study we show how the Pattern ERG (PERG) can be used to distinguish between optic nerve and retinal disease. Records from eyes with RBN and delayed visual evoked responses are compared with those recorded from the normal fellow eyes. In optic nerve disease there is a selective reduction of the later negative component of the response. PERG's were also recorded from patients with mild diabetic retinopathy. These were divided into three groups on the basis of the delay in their Visual Evoked Potential (VEP). The amplitude of both positive and negative components fall with increasing severity of the disease thus showing that the abnormally long delau in VEP found in some cases is due to retinal disease rather than optic nerve disease.

Adolescent↗
PubMed1988

The pattern electroretinogram (PERG) in ocular hypertension and glaucoma.

Studies of normal subjects and of patients with optic nerve disorders suggest that one of the components of the pattern electroretinogram (PERG), the second negative wave, is related to optic nerve function and appears to be diminished even when the condition is relatively mild, with little alteration of visual acuity. It is known that significant loss of nerve fibers may occur prior to the development of visual field loss. We have investigated the PERGs of a group of subjects with early glaucoma and ocular hypertension, comparing them with normal subjects, and have found a selective reduction in the second negative wave in patients with evidence of optic nerve dysfunction. The PERG may prove helpful in discriminating those patients with ocular hypertension who are destined to develop visual field loss unless medical or surgical therapy were to be employed.

Adolescent↗
PubMed1988

Cost of neonatal care.

A six month evaluation of the costs of a regional neonatal medical and surgical unit was carried out. The total cost for six months was pounds 970,000 and this covered 4349 inpatient days and 282 admissions. For medical cases the cost ranged from pounds 132 to pounds 27,600 and the mean daily cost for different weight groups ranged from pounds 159 to pounds 274. The average daily cost for regional patients at pounds 258 was greater than for district patients who cost pounds 199. Altogether 23 medical patients weighing less than 1000 g at birth were admitted. The total cost for nine of these infants who died was pounds 30,991-about 3% of the unit's total budget.

Costs and Cost Analysis↗
PubMed1988

Mineral accretion in the human fetus.

Bone mineral content of the mid forearm was measured by photon absorptiometry in 73 white singletons (36 boys, 37 girls) born between 18 and 43 weeks' gestation. Results obtained within two weeks of birth for liveborn infants were used to establish bone mineral deposition curves approximating normal in utero development. Results for stillborn infants indicated a retardation of bone mineralisation relative to liveborn infants. This has important implications concerning previous estimates of daily calcium needs for preterm infants. Eleven liveborn Asian singletons and nine pairs of white twins were examined similarly. With respect to bone mineral content, weight, and crown-heel length, Asians with gestational ages over 35 weeks and twins were closely comparable with their white singleton peers. Asians under 35 weeks tended to be smaller than white singletons of comparable age.

Asia↗