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Biomedical subjects

P D Hill

Publications and source records attributed to P D Hill.

At least 19 recordsLinked to original sources
PubMed2000

Review of interface pressure measurement to establish a protocol for their use in the assessment of patient support surfaces.

The interface pressure (IP) between a body and support surface is one objective measure used in the evaluation of the wide variety of pressure relieving equipment that exists for the prevention and treatment of pressure sores. We present a review of the literature associated with making these measurements and discuss the acute need to be able to use them to choose the most effective 'anti-pressure sore devices' for patient care, as well as discussing the difficulties associated with this decision making. We focus on interface pressure monitors describing their development and discussing the questions that remain about the accuracy and relevance of their measurements. An outline of the strengths and limitations of the most commonly used pressure sensors is given. There remains a gap in research in this area that is clinically specific and the need to be able to assess these anti-pressure sore devices with patients in a hospital environment is highlighted. The variants involved in assessing patients on various mattresses and the difficulties associated with this are described. A protocol is suggested in an attempt to improve the use of such devices and establish a better method for quantifying the clinical effectiveness of different support surfaces.

Beds↗
PubMed2000

Uvulopalatopharyngoplasty versus laser assisted uvulopalatoplasty for the treatment of snoring: an objective randomised clinical trial.

This study was designed to evaluate objectively the clinical effectiveness of surgery for snoring and to compare the results of conventional uvulopalatopharyngoplasty (UPPP) and laser assisted uvulopalatoplasty (LAUP) in the treatment of snoring. Patients who had been referred for investigation and treatment of their snoring were randomly allocated to receive either UPPP or LAUP. Forty-seven patients with confirmed palatal flutter had surgery and all of them had a preoperative and postoperative objective assessment of their snoring loudness and duration in the home. The recording device (Snore Box) is simple for the patient to operate, portable with a built in microphone, and able to produce objective results, which can be automatically analysed. Of the 38 patients, who had technically valid recordings, 22 underwent LAUP and 16 UPPP. Overall the mean postoperative Snore Index (SI) was less than the preoperative SI (P < 0.0001), the average difference being 78.2 snores/h. There was no significant difference between the LAUP and UPPP regarding the fall in the SI. This study is the first objective comparative study to demonstrate the effectiveness of snoring surgery.

Adult↗
PubMed2000

Changes in snoring during natural sleep identified by acoustic crest factor analysis at different times of night.

Sleep nasendoscopy can be used to identify the site of snoring but questions remain about how well a short assessment during drug-induced sleep reflects the natural condition. To investigate the uniformity of snoring during natural sleep we studied five patients (three men, two women) referred by their GPs for treatment of their snoring. A digital audio tape recorder captured the free-field snore sound at different times of night in hospital. Acoustic Crest Factor values were calculated on the 15 recordings made, having previously demonstrated that high crest factor values distinguish palatal from non-palatal snoring at sleep nasendoscopy. Some recordings showed reproducibility, but others showed substantial changes between recordings an hour apart. We infer that the snoring mechanism may change in some individuals during the night, with or without a change of snore site. We conclude a single recording, as in sleep nasendoscopy, may not be representative.

Acoustics↗
PubMed2000

Relation of plasma oxytocin and prolactin concentrations to milk production in mothers of preterm infants: influence of stress.

Responses of oxytocin and PRL to mechanical breast pumping and the influence of physiological indicators of stress were measured at 2, 4, and 6 weeks postpartum to determine potential causes of inadequate milk production in 18 women with prematurely delivered, nonnursing (<1500 g) infants. Median milk production was similar to that reported in breastfeeding mothers, but a third of mothers were producing less than half as much by week 6. Plasma oxytocin was similar to that previously reported for breastfeeding mothers. The oxytocin area under the curve (AUC) for breast-pumping sessions (70 min) was correlated at each occasion (r = 0.37, 0.58, and 0.55, respectively) with milk yield. Unlike reports of PRL levels in breast-feeding women, PRL AUC declined between weeks 2 and 6 weeks postpartum (P = 0.03); significant increases in plasma PRL occurred in response to pumping at 2 and 4 weeks, but not at 6 weeks. Salivary amylase, a measure of alpha-adrenergic activity, was highly negatively correlated on each occasion with PRL AUC (r = -0.58, -0.68, and -0.86, respectively), but not with oxytocin. Salivary cortisol was negatively correlated to a lesser degree. We hypothesize that deficiencies in preterm lactation are mediated in part upon stress-induced suppression of PRL secretion through an adrenergic mechanism.

Adult↗
PubMed1999

A new acoustic method of differentiating palatal from non-palatal snoring.

Palatal snoring produces explosive peaks of sound at very low frequency (approximately 20 Hz). Using a digital sound trace a ratio of peak amplitude to root mean square amplitude can be calculated. This Peak Factor Ratio is significantly higher for palatal snores than non-palatal snores (P < 0.01). This acoustic method will be useful for selecting patients for palatal surgery as it is non-invasive and could be used in a home monitor.

Acoustics↗
PubMed1999

The Epworth Sleepiness Scale: can it be used for sleep apnoea screening among snorers?

Snoring is a common disorder and may lead to the development of Obstructive Sleep Apnoea (OSA) with its associated hazards. Differentiation of patients with OSA from patients with simple snoring is crucial to the ENT surgeon before selecting treatment. This study aimed to assess the reliability of the Epworth Sleepiness Scale (ESS) to screen for OSA among snorers. Forty-six patients referred for treatment of snoring were studied. Each patient completed the ESS questionnaire and subsequently underwent a hospital sleep study. The ESS scores did not correlate with the apnoea/hypopnoea indices calculated from the sleep studies (correlation coefficient 0.12). The lack of correlation is mainly because simple snorers can also suffer from excessive daytime sleepiness, due to an unclear mechanism. The ESS is a useful questionnaire for assessing disability as a result of snoring but it is of no value in distinguishing simple snorers from patients with OSA.

Adult↗
PubMed1999

Breastfeeding experience and milk weight in lactating mothers pumping for preterm infants.

BACKGROUND: Research about parity or breastfeeding experience and its relationship with milk production in humans is limited. The purpose of this study was to determine if any difference in milk volume occurred among mothers with and without breastfeeding experience who used either a single or double breast pumping regimen the first 5 weeks postpartum. METHODS: A convenience sample of 39 mothers of nonnursing preterm infants participated from two tertiary care centers in the midwestern United States. The sequential single pumping group consisted of 20 mothers, 7 of whom had previous breastfeeding experience; the simultaneous double pumping group consisted of 19 mothers, 2 of whom had previous breastfeeding experience. Income and pumping group regimen were used as blocking variables, and average frequency of kangaroo care per week and average frequency of breast pumping per week were covariants in the repeated measures analysis of variance. RESULTS: Mothers with previous breastfeeding experience had greater milk weights over time, but weights were not significantly different when compared with those mothers with no previous breastfeeding experience. Additional analysis with the covariants of pumping frequency and kangaroo care, and with the independent variables of group, breastfeeding experience, and income resulted in statistically significantly greater milk yield in the women with previous breastfeeding experience. CONCLUSIONS: The findings of the two repeated analyses indicated the complexity of the milk production response, and the importance of considerations of environmental as well as physiologic factors.

Adolescent↗
PubMed1999

A simple audio data logger for objective assessment of snoring in the home.

We have developed a portable device for patient use in logging snoring loudness in the home, for guiding treatment decisions and measuring the clinical effectiveness of treatment. The device uses a free field microphone and is positioned on a bedside table. The prototype devices contain no inherently expensive components and are simple to operate (producing only 5% patient error to date). They are portable, battery powered, rugged and produce digital data which are easily and automatically analysed, and these design parameters enable the devices to be used for first line patient assessment. Of the 75 recordings made so far from 30 patients, 85% were successful, yielding clinically useful data. Because it is sound levels which are recorded and not replayable sounds, patient privacy is maintained, resulting in excellent patient acceptance (to date no patient has refused). The device has a dynamic range of 45-90 dB sound pressure level and a frequency range of 30 Hz-5 kHz. Because snoring intensities often vary significantly throughout the night the device can measure continuously over 8 h.

Calibration↗
PubMed1999

Palatal snoring identified by acoustic crest factor analysis.

The differentiation of palatal from non-palatal snoring is very important for ENT surgeons trying to determine whether palatal surgery would be curative. At present sleep nasendoscopy is the accepted method. Palatal vibration produces marked modulation of sound loudness at low frequency (below approximately 100 Hz). We calculate a crest factor for the sound waveform (ratio of peak to root mean square (rms) value in any given epoch), as a measure of the degree of modulation. Free-field snore sounds were recorded from 11 supine adult patients under intravenous sedation (midazolam), using a digital tape recorder. Recordings were transferred to a PC (sampling frequency 11 kHz), and analysed using code written by us. Direct visual confirmation of the site of snoring was gained from simultaneous sleep nasendoscopy, taken as the gold standard. In six patients the dominant site was the soft palate. The non-palatal group (five patients) comprised one epiglottic, two hypopharyngeal and two tongue base snorers. The crest factor was found to be significantly higher for palatal snorers (p < 0.01, Student-t or Mann-Whitney tests). Furthermore, palatal could be distinguished from non-palatal snorers on the basis of crest factor alone in all 11 cases, making this a promising non-invasive diagnostic technique.

Acoustics↗
PubMed1999

Effects of pumping style on milk production in mothers of non-nursing preterm infants.

Milk production was examined in 39 lactating mothers of non-nursing preterm infants from 2 tertiary care centers. The purposes of this study were (1) to compare milk production of those using sequential single (SEQ) or simultaneous double (SIM) breast-pumping regimen, and (2) to examine the relationship of selected variables to inadequate (< 3500 g/week) and adequate (> or = 3500 g/week) milk production. In multivariate analysis, mothers using SIM produced a similar amount of milk by weight during weeks 2 to 5 postpartum compared to those using SEQ. A logistic regression model including frequency of kangaroo care, frequency of pumping, high versus low income, and previous breastfeeding experience was predictive of mothers producing adequate versus inadequate milk volume 79% of the time. All of the mothers producing > 3500 g at week 2 produced adequate amounts of milk at weeks 4 and 5. None of the mothers producing < 1700 g at week 2 reached adequate production by weeks 4 and 5. Of the remaining mothers who produced 1700 g to 3500 g at week 2, 54% achieved adequate production during weeks 4 and 5 postpartum.

Adult↗
PubMed1999

Serum prolactin in breastfeeding: state of the science.

Prolactin is one of two major hormones involved in lactation. While the role of infant suckling and oxytocin in the lactation process are well understood, the role of prolactin is less clear. A variety of factors related to prolactin have been investigated, and these are used as an organizing framework for this article. Factors include pregnancy, lactation, nursing frequency, prior lactation experience, milk production, and pharmacologic agents. The literature, while substantial in amount, presents inconsistencies. Implications for practice are discussed.

Breast Feeding↗
PubMed1998

Snoring assessment: do home studies and hospital studies give different results?

We have developed a device (Glan Clwyd Snore Box) suitable for the objective measurement of the loudness and duration of snoring. The device is simple for the patient to operate, portable, battery powered, and able to produce objective results. We have used the Snore Box to record the snoring at home and during sleep studies in the hospital. Twenty-nine patients were studied. Overall the Snore Index recorded in the home was greater than in the hospital (P < 0.001), the average difference being 67 snores/h. We conclude that snoring is more appropriately assessed at home than in the hospital. We suggest the deficit arises from sleeping in an unfamiliar environment and the presence of several wires connecting the patient to the recording monitor which interfere with natural sleep in the hospital setting.

Adult↗
PubMed1998

Breastfeeding and health professional encouragement.

The objective of the study was to ascertain the nature of health professional contacts related to breastfeeding for 341 women. Subjects were prospectively queried by phone or home visit over a 20-week period regarding the number and nature of contacts with health care professionals related to breastfeeding. Lactation consultants gave significantly more positive encouragement (98%) (p = .01) than either nurses (75%) or physicians (68%) did. However, of the 233 health provider contacts that included breastfeeding advice, only 21% involved lactation consultants. Primiparae were likely to decrease their level of breastfeeding if a health professional encouraged supplemental foods (39%) or weaning (86%) during the prior week. Multiparae who were experienced at breastfeeding (3+ weeks breastfeeding the previous infant) decreased their breastfeeding slowly across the weeks with the current infant, and their level of breastfeeding in general appeared independent of health care provider advice. Multiparae who lacked previous sustained breastfeeding experience (0-3 weeks) had the most rapid decrease (65%) in their breastfeeding rates even with health care provider encouragement to continue. Thus, they too appeared to act independently of health care provider advice.

Adult↗
PubMed1998

Audit of service to a minority client group: male to female transsexuals.

Male to female transsexual clients are a group of clients for whom there are few dedicated services in New Zealand. To examine service utilization in Wellington, New Zealand, 70 male to female transsexual clients were identified and their medical records audited for selected aspects of sexual health service delivery. Audit revealed that sexual health history is recorded incompletely and behavioural risk factors are not fully explored, sexual health examination and testing is incomplete. We conclude opportunities to expose relevant behavioural factors and to educate for sexual safety and health promotion are lost with this infrequently attending minority client group.

Adult↗
PubMed1998

Breast-milk sodium as a predictor of breastfeeding patterns.

This study partially replicates and extends a study reporting that elevated breast-milk sodium BM [Na+] during early lactogenesis was predictive of poor breastfeeding outcomes. The present study used 6-day postpartum breast milk. Consistent with the findings of the earlier study, 80% of those with a BM [Na+] of 16 mmol/L or lower at day 6 sustained a high level of breastfeeding at week 4, compared to only 50% of those with an elevated BM [Na+] (chi 2 = 4.05, df = 1, p = .04). This difference was even greater in a subgroup of mothers predicted to be at high risk for insufficient milk supply on the basis of support density and self-perception variables. Of the latter group, 75% with low BM [Na+] sustained a high level of breastfeeding at 4 weeks postpartum, compared to only 22% with an elevated BM [Na+] (chi 2 = .65, df = 1, p = .01). In contrast, among the low-risk mothers BM [Na+] levels were not associated with any difference in breast-milk sustainment (89% and 82% sustainment for low- and high-sodium groups, respectively). Thus a normal drop in BM [Na+] is predictive of higher sustainment of breastfeeding. However, the predictive validity of this marker appears to be enhanced by combining it with the psychosocial variables of support density and self-perception of breastfeeding by the mother.

Adult↗
PubMed1997

Does early supplementation affect long-term breastfeeding?

The purpose of this secondary data analysis from two different samples was to examine the effect of early supplementation with manufactured milks on breastfeeding status at 20 weeks postpartum in mothers of healthy term infants. In two convenience samples of 120 and 223, respectively, breastfeeding mothers were followed up for 20 weeks postpartum or until weaning occurred. The breastfeeding rate at 20 weeks postpartum was significantly greater for mothers who reported feeding exclusively mother's milk the second week after delivery compared with mothers who breastfed and simultaneously supplemented with manufactured infant milks. Of the mothers in samples one and two who exclusively fed human milk during week 2 postpartum, 63.0% and 59.7%, respectively, were still breastfeeding at week 20, compared with 28.1% and 24.2%, respectively, who supplemented with artificial milks. There was no significant difference between these two groups of mothers and their intended duration of breastfeeding. Early introduction of supplemental bottles of artificial milks is associated with a decrease in the amount of human milk the infant receives as well as with early weaning.

Bottle Feeding↗