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Biomedical subjects

D Byrne

Publications and source records attributed to D Byrne.

18 recordsLinked to original sources
PubMed1992

Fetal nuchal translucency: ultrasound screening for chromosomal defects in first trimester of pregnancy.

OBJECTIVE: To examine the significance of fetal nuchal translucency at 10-14 weeks' gestation in the prediction of abnormal fetal karyotype. DESIGN: Prospective screening study. SETTING: The Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London. SUBJECTS: 827 fetuses undergoing first trimester karyotyping by amniocentesis or chorionic villus sampling. MAIN OUTCOME MEASURE: Incidence of chromosomal defects. RESULTS: The incidence of chromosomal defects was 3% (28 of 827 cases). In the 51 (6%) fetuses with nuchal translucency 3-8 mm thick the incidence of chromosomal defects was 35% (18 cases). In contrast, only 10 of the remaining 776 (1%) fetuses were chromosomally abnormal. CONCLUSION: Fetal nuchal translucency > or = 3 mm is a useful first trimester marker for fetal chromosomal abnormalities.

Adult↗
PubMed1992

Hepatic resections for primary and metastatic tumors using the ultrasonic surgical dissector.

We have previously described the development of new hepatic surgical techniques using the ultrasonic surgical dissector. With 10 years' experience, we have found that major liver resections have been simplified and that the technique is repeatable in hands other than our own. Thirty-three patients had 37 tumors, averaging 5.65 cm in size, resected with an average blood loss of only 1,020 mL per case, which included 5 right trisegmentectomies, 12 lobectomies, 15 segmental resections, and 4 subsegmental resections. Twenty-two patients had metastatic colorectal cancer. Blood transfusion requirements averaged only 2.24 units in long-term survivors, which was significantly less than the 3.5 units received by patients who have since died (p = 0.092). There were no operative deaths. The median survival of these 22 patients was 56 months, and the 5-year actuarial survival rate was 35%. All of the early deaths occurred in patients with more than four tumors, and no patient with less than four tumors died before 42 months with recurrent disease. Six patients had bilateral tumors, and the fact that patients survived into the fourth and fifth post-resectional year indicates that resection was worthwhile. All these patients had Dukes' C primary tumors, but we found no statistical difference in survival between patients with Dukes' B and Dukes' C lesions. The results indicate that hepatic resection with the ultrasonic surgical dissector decreases blood loss, requires few transfusions, is safe to perform, and is associated with excellent long-term survival.

Adolescent↗
PubMed1992

Cost-effectiveness of single dose cefotaxime plus metronidazole compared with three doses each of cefuroxime plus metronidazole for the prevention of wound infection after colorectal surgery.

The cost-effectiveness of prophylaxis for colonic surgery with single dose cefotaxime plus metronidazole has been compared with that of three doses each of cefuroxime plus metronidazole, by analysing data from a previously published study supplemented with additional data on the hospital and community costs of wound infection after colonic surgery. The original trial included 942 patients having elective colonic surgery in 14 hospitals. The data on costs of wound infection were collected from a further 124 patients undergoing elective colonic surgery at Ninewells Hospital. All these patients received a three dose regimen of cefuroxime plus metronidazole. The Dundee patients received three injections of 0.75 g cefuroxime at 8-hourly intervals whereas the trial patients received a single dose of 1.5 g followed by two further doses of 0.75 g at 8-hourly intervals. The cefuroxime prophylaxis regimen used in the trial cost 24.16 pounds per patient more than the cefotaxime regimen. The components of the excess cost were drugs (15.18 pounds), equipment (6.14 pounds) and staff time (2.84 pounds). The median cost to the hospital of a wound infection was 978.04 pounds (95% CI 482.04 pounds to 1521.22 pounds). The components of the hospital cost of wound infection were: hotel costs 858 pounds (88%), dressing costs 83.02 pounds (8%) and drug costs (excluding prophylaxis) 37.02 pounds (4%). Only five patients received additional antibiotic treatment in the community, and only one required home visits from the District Nurse. Applying the difference in costs of prophylaxis as 21 pounds (costs of drugs plus equipment) and the cost per wound infection as 1000 pounds to the observed wound infection rate of 7% in the cefuroxime group, the wound infection rate in the cefotaxime group would have to be 2.1% higher for the two regimens to be equally cost-effective. The probability that such a difference in efficacy exists is 0.088. A model was developed to calculate the probability of equal cost-effectiveness over a range of costs of wound infection.

Anti-Infective Agents↗
PubMed1992

The emergence of clinical psychology departments in Australian teaching hospitals.

Over recent years, clinical psychological services have diversified within the health sector, leading to a breakdown in the traditional nexus between clinical psychology and psychiatry, and to the emergence of the interdisciplinary field of behavioral medicine. From their earlier limited role as providers of psychometric assessments in educational and psychiatric hospital settings, clinical psychologists now provide a wide range of therapeutic services and research skills to general hospitals, universities, community health centres, and the private sector. This evolving trend has significant implications for the future structure and direction of clinical practices in clinical psychology, psychiatry and medicine.

Adaptation, Psychological↗
PubMed1992

Effects of long-term bilateral and unilateral fitting of different hearing aid types on the ability to locate sounds.

Aided localization ability of 87 hearing-impaired listeners was tested for horizontal and vertical sound sources, at two signal levels, and for two orientations to the loudspeaker array (facing, sideways). Some listeners wore behind-the-ear (BTE) aids, others in-the-ear (ITE) aids. Some were bilaterally fitted, others unilaterally fitted. Listeners were tested only with types of aids and fittings that they were accustomed to wearing. The results strongly supported bilateral fitting for moderately and severely hearing-impaired listeners. However, for mildly impaired listeners, those fitted unilaterally performed as well, on average, as those fitted bilaterally. This suggests a need to consider individual listening requirements and also to provide such listeners with experience in unilaterally-aided listening before assessing the possible advantages of bilateral fitting. When hearing level was controlled, there was no overall difference in the performance of ITE and BTE aid wearers. This discrepancy with other research may be explained by measures (removal of intensity cues, permitting of head movement) designed to make the test situation more representative of real-life listening.

Adult↗
PubMed1992

Key issues in hearing aid selection and evaluation.

This article examines three key issues in hearing aid selection and evaluation. First, two studies are analyzed to determine the extent to which differences in frequency response characteristics result in differences in judgments of the intelligibility or pleasantness of amplified speech. Small to moderate frequency response differences usually did result in different judgments although occasionally large differences did not. When two dissimilar responses are equally intelligible, it is likely that the best response is something in between them. Second, evidence indicates that it is not always satisfactory to allow frequency response to be determined by prescribing gain at each frequency separately. This suggests, therefore, that separate frequency response prescription rules are needed. Third, signal audibility is discussed in the context of using simplified Articulation Index schemes to predict aided performance. It is demonstrated how wrong conclusions may easily be drawn in the absence of accurate knowledge of the signal levels received when different hearing aid options are used. Data suggest that the Articulation Index may not be applicable to steeply sloping high-frequency hearing losses. This needs further investigation before the Articulation Index can be recommended for hearing aid evaluations.

Correction of Hearing Impairment↗
PubMed1991

A comparison of diagnostic related group length of stay outliers: motor vehicle crash versus penetrating injuries.

The incidence and degree to which patients injured by motor vehicle crashes (MVCs) and penetrating wounds remain in the hospital beyond the diagnostic related group (DRG) mean length of stay (LOS) are compared. During a 12-month period, records for consecutive patients admitted to eight hospitals (including three trauma centers) were studied. Patients aged 13 or younger, staying less than 48 hours, or with major burns or only distal fractures were excluded. In that time, 2,914 patients were eligible. Twenty percent of injuries were penetrating; 27% were MVC injuries; and, 53% were blunt injuries from other causes. Patients injured in MVCs and with penetrating injuries were compared with respect to mean LOS, incidence of DRG outliers, number of hospital days beyond the DRG mean LOS, and demographic variables. Patients injured in MVCs had a greater proportion of DRG LOS outliers and higher mean numbers of DRG excess days than did patients with penetrating wounds (p less than 0.01, for both). Injuries were distributed among relatively more DRGs for MVC patients. The DRG scheme may lack sufficient attention to factors more likely to affect MVC patients, such as multiplicity of injuries, incidence of CNS injuries, ICU requirements, and older age. In structuring more appropriate reimbursement for trauma care, special attention must be paid to patients injured in MVCs.

Accidents, Traffic↗
PubMed1991

Human and non-financial costs of hospital-acquired infection.

Measurement of morbidity from hospital-acquired infection should include the suffering of patients who are denied treatment, 'the opportunity cost of infection'. We believe that this perspective will also reveal other inefficiencies which may be easier to correct than hospital-acquired infection. Infection control should be seen as a component of quality control and not as an end in itself.

Cost-Benefit Analysis↗
PubMed1991

Why cell culture is successful after early amniocentesis.

The current interest in early amniocentesis as a possible alternative to chorion villus sampling has driven many centres to attempt cell culture from first trimester amniotic fluid. This study examines the cellular content of 125 amniotic fluid specimens collected between 8 and 18 weeks of gestation and shows that there is a higher proportion of viable cells at the time of early amniocentesis than at traditional amniocentesis. Although there is a small increase in viable cell number from 8 to 18 weeks of gestation, this is not as dramatic as the exponential rise in total cell number seen over the same period. The similar concentration of viable cells in early pregnancy to that in the second trimester is sufficient to explain the unexpected culture success after early amniocentesis.

Amniocentesis↗
PubMed1991

Auditory localization under conditions of unilateral fitting of different hearing aid systems.

The spatial localization function of hearing-impaired listeners, usually fitted bilaterally with BTE, ITE or ITC devices, was tested under conditions of unilateral fitting of each of their own hearing aids, and unilateral fitting of stock versions of each of the other types. For the BTE wearers average localization accuracy and individual variability were not greatly changed when wearing only their left ear device, compared with bilateral aided performance. In ITE wearers, unilateral fitting in either ear led to somewhat poorer performance than bilateral. In the ITC wearers unilateral fitting produced inconsistent outcomes. Both BTE and ITE wearers fared poorly when fitted unilaterally with stock forms of devices 'foreign' to them, whereas ITC wearers did not show such a contrasting outcome. A group of non-impaired listeners showed severe disruption of localization under unilateral BTE and ITC hearing aid conditions, and to a lesser extent with ITEs. Results for the hearing-impaired listeners are interpreted in terms of adaptation to different usage patterns, with BTE wearers suggested as having adapted to their own systems unilaterally as well as bilaterally.

Auditory Threshold↗
PubMed1990

Hearing aid gain and frequency response requirements for the severely/profoundly hearing impaired.

The optimal frequency response slope, from the low frequencies (250 or 500 Hz) to 2000 Hz, was estimated for each of 46 severely or profoundly hearing-impaired adults. The estimates were derived from paired comparison judgments of speech filtered to simulate different frequency response conditions, from home trials and ratings of different tone settings of high-powered, behind-the-ear hearing aids, and for 28 subjects, from speech recognition testing. The estimated optimal response, expressed as the slope from 250 to 2000 Hz and as the slope from 500 to 2000 Hz, was compared with the response prescribed by the National Acoustic Laboratories (NAL) procedure and its relationship to audiometric variables was analyzed. Insertion gain was measured for the preferred volume setting with the best frequency response. Preferred gain was typically about 10 dB higher than the NAL prescribed gain. Considering these results in relation to other data, it appears that the "half-gain" rule ceases to apply when HTL exceeds about 70 dB. The estimated optimal frequency response agreed with the NAL response for some subjects but relatively more low frequencies were required for between a third and half of the subjects, depending upon how frequency response is expressed. Generally, more low frequencies were required if HTL at 2000 Hz exceeded 95 dB, whereas the NAL response was usually appropriate for other cases.

Adult↗
PubMed1990

A comparison of different binaural hearing aid systems for sound localization in the horizontal and vertical planes.

Three groups of hearing-impaired listeners who had been fitted binaurally with behind-the-ear (BTE), in-the-ear (ITE), or in-the-ear-canal (ITC) hearing aids were tested on spatial localization function for sources in the frontal horizontal and vertical planes. No significant differences in unaided performance were observed between the groups, nor between that and aided performance in the BTE and ITE wearers. ITC wearers, by contrast, showed a deterioration in aided over unaided performance. From observations of performance when each group wore temporary fittings of the other two types of system, and from the performance of a non-impaired control group, it appears that the performance decrement for the ITC wearers was due to their own particular systems although specific reasons for this decrement could not be identified. In all conditions, aided and unaided, vertical plane localization was markedly disrupted in all the hearing impaired groups. It was also disrupted, to a lesser but still substantial extent, in aided conditions for the non-impaired listeners.

Adult↗
PubMed1979

Hearing aid selection. An analysis and point of view.

Hearing aid selection and hearing aid evaluation are related, but separate, processes. Adequate selection must precede evaluation, which can only be applied to a few of the limitless amplification possibilities. I discuss the theoretical principles of aid selection and illustrate their application by reference to aid selection procedures developed in the National Acoustic Laboratories, Australia. Unless selection is arbitrary, a theoretical method is being used even if not recognized or applied consistently. It is argued that casual methods cannot be adequate and should be replaced by the adoption of theoretical procedures that are explicit, systematic, comprehensive, and subject to critical examination and refinement.

Acoustics↗
PubMed1978

Selection of hearing aids for severely deaf children.

Procedures are described for selecting the gain and frequency response of hearing aids for deaf children and for evaluating aided hearing. These include a comparison of aided thresholds with the speech spectrum to determine how much of the frequency range is functional for each child. This provides a basis for deciding whether to select an aid having a "conventional" (C) response, which de-emphasises the low frequencies, or a low frequency (LF) response which provides more low frequency gain, although not necessarily low frequency emphasis. It is concluded that, for optical aid fitting, some children require "C" responses for both ears, others "LF" responses for both ears and others a "C" response for one ear and an "LF" response for the other. These three possibilities are all required sufficiently commonly that exclusive use of any one would inevitably result in relatively ineffective amplification for many deaf children.

Audiology↗
PubMed1977

The speech spectrum--some aspects of its significance for hearing aid selection and evaluation.

A spectral analysis of Australian speech is reported for 30 speakers, 15 males and 15 females. When expressed in one-third octave band levels, or critical band levels, the spectrum is essentially flat from 1kHz to 8KHz and shows approximately 15dB greater energy at 0.5kHz and lower frequencies. Although the results of this study agree substantially with other published data, the use of the average spectrum obtained, rather than the idealised speech spectrum, would be significant for aid selection and evaluation purposes. The common practice, in hearing aid literature, of showing the speech spectrum expressed in spectrum levels, rather than one-third octave band levels, may lead to a different, and possibly misleading, conceptualisation of the relative energy of high and low frequency components. Considering that speech spectra differ greatly from one individual to another, it would seem desirable that speech with a known, preferably average, spectrum be used in hearing aid evaluation procedures which involve setting the volume control of a hearing aid to deliver speech at a comfortable listening level.

Female↗
PubMed1977

Towards a method for assessing social support systems.

Man is committed by his biological and cultural evolution to a social existence. While the social environment is the source of many stressors, it may also be protective. This latter function is called 'support'. Social bonds are to be found universally, but some cultural groups have the integrity of these bonds conspicuously endangered. The application of the affective component of the social network to psychiatry promises to be useful, but cannot progress further until an instrument is developed for assessing the support available to an individual. We have gone some way towards a method for assessing the components of primary group interaction. The task now is to determine if low social support, such as is seen in Western suburban wives, some migrant groups and some women in the Middle East and Asia, is causally related to some psychiatric disorders The principal appeal of this area is that we may be tapping something very fundamental about human social organisation, something which, unlike adversity, is subject to modification.

Community Psychiatry↗
PubMed1976

Effect of para-aminohippurate on renal glutamine metabolism in the rat.

After para-aminohippurate (PAH) infusion into rats, urine pH decreased and urine ammonium excretion increased. Because augmented urine flow and decreased urine pH could not explain entirely the enhanced ammonium excretion, an increased ammonia production was postulated as a contributing influence. This was supported by the in vitro findings that PAH could increase slice ammoniagenesis from glutamine. The ability of PAH to stimulate ammoniagenesis in vitro was attributed to enhanced phosphate-dependent glutaminase activity. We conclude that PAH infusions at certain concentrations in vivo can alter ammonium excretion through increased renal ammonia production. The latter may be secondary to enhanced phosphate-dependent glutaminase activity.

Aerobiosis↗