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Biomedical subjects

A J McPhee

Publications and source records attributed to A J McPhee.

14 recordsLinked to original sources
PubMed2003

Early discharge with home support of gavage feeding for stable preterm infants who have not established full oral feeds.

BACKGROUND: Early discharge of stable preterm infants still requiring gavage feeds has the potential benefits of uniting families sooner and reducing health care and family costs compared to discharge home when on full sucking feeds. Potential disadvantages include the increased burden for the family and the possibility of complications related to gavage feeding. OBJECTIVES: To determine the effects of a policy of early discharge of stable preterm infants with home support of gavage feeding compared with a policy of discharge of such infants when they have reached full sucking feeds. SEARCH STRATEGY: The standard search strategy of the Cochrane Neonatal Review Group was used together with additional searches of the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2003), CINAHL (1982 to April week 1 2003), EMBASE (1980 to 2003 week 15) and MEDLINE (1966 to April week 1 2003). SELECTION CRITERIA: All randomised and quasi-randomised trials among infants born <37 weeks and requiring no intravenous nutrition at the point of discharge were included. Trials were required to compare early discharge home with gavage feeds and health care support with later discharge home when full sucking feeds were attained. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. Data analysis was done in accordance with the standards of the Cochrane Neonatal Review Group. MAIN RESULTS: Data from one quasi-randomised trial, with 88 infants from 75 families, were included in the review. Infants in the early discharge program with home gavage feeding had a mean hospital stay that was 9.3 days shorter [MD -9.3 (-18.49 to -0.11)] than infants in the control group. Infants in the early discharge program also had a lower risk of clinical infection during the home gavage period compared with the corresponding time in hospital for the control group [RR 0.35 (0.17 to 0.69)]. There were no significant differences between groups in duration and extent of breast feeding, weight gain, re-admission within the first 12 months post discharge from the home gavage program or from hospital, scores reflecting parental satisfaction, or health service use. REVIEWER'S CONCLUSIONS: Experimental evidence to evaluate the benefits and risks in preterm infants of early discharge from hospital with home gavage feeding compared with later discharge upon attainment of full sucking feeds is limited to the results of one small quasi-randomised controlled trial. High quality trials with concealed allocation, complete follow-up of all randomised infants and adequate sample size are needed before practice recommendations can be made.

Enteral Nutrition↗
PubMed2000

Effects of birthweight and oxygen supplementation on lung function in late childhood in children of very low birth weight.

Impaired respiratory function has been found frequently in ex-premature children, but it is unclear which specific factors influence this impairment the most. The aim of this study was to determine the importance of the contributions of birth weight, gestational age, neonatal respiratory disease, and its treatment on subsequent childhood lung function at age 11 years in a cohort of children of very low birth weight (VLBW; </=1,500 g). Detailed clinical histories were recorded, and lung function was measured in 60% (102 children) of surviving VLBW infants born 1981/1982, and compared with 82 matched control children (birth weight >2,000 g) of similar age. VLBW children were shorter and lighter than controls (P < 0.0001) at 11 years of age, and had reduced expiratory flows (P < 0.00001) and forced vital capacities (P < 0.001). The residual volume to total lung capacity ratio (RV/TLC ratio) was increased (P < 0.00001), while total lung capacity (TLC) remained unchanged. Those with bronchopulmonary dysplasia (BPD) had the lowest mean expiratory flows. Males had lower expiratory flows than females. On univariate analysis, gestational age by itself accounted for 8.8% of the explained variance in FEV(1) at 11 years of age, but birth weight accounted for 16% on its own; both together accounted for a further 0.2% (16.2%), suggesting that the latter was the dominant factor. On multivariate analysis, the contribution of birth weight and gestational age was small, and the best predictors at 11 years of age, which together explained 43.4% of the total variance in FEV(1), were log days of supplemental oxygen (9.6%) and a reported history of asthma (10.8%). For FEF(25-75), these predictors explained 7.2% and 13.4%, respectively, of the total explained variance of 40.6%. The relation between neonatal oxygen supplementation and childhood FEV(1) was such that up to 20 days of supplemental oxygen had little effect on subsequent FEV(1) at 11 years of age, but each additional week of supplemental oxygen after that time was associated with a progressive reduction in FEV(1) of 3%. These data confirm the significant role of supplemental oxygen in the neonatal period and a history of asthma on the subsequent reduction of expiratory flows in VLBW children. Birth weight was a more important prenatal factor than gestational age, but both were of lesser predictive significance than either supplemental oxygen or a reported history of asthma.

Asthma↗
PubMed2000

The influence of variations in blood flow on pulsed doppler ultrasonic heating of the cerebral cortex of the neonatal pig.

Pulsed Doppler ultrasound examination of the fetal cerebral circulation may cause potentially harmful temperature elevations in brain tissue immediately beneath the insonated segment of the skull. This study measured the effect of variations in cerebral blood flow on ultrasonic heating of the cerebral cortex of anaesthetised, neonatal pigs. Wide and narrow ultrasound beams were used. Pulsed ultrasound exposures were delivered in 90 s bursts at 5.8 micros pulse length, pulse repetition frequency 8 kHz and centre frequency 3.5 MHz. Studies were performed with the target at the focus of a fixed, stationary beam of 0.3 cm -6 dB beam width (narrow beam) and I(spta) 1.4 W/cm(2) (n = 11), or with the target in the near field of a fixed, stationary beam of 1.6 cm -6 dB beam width (wide beam) and I(spta) 3.6 W/cm(2)(n = 5). The 90 s ultrasound exposures were performed under three different conditions of ambient cerebral blood flow: baseline (during normocarbic, normoxic conditions), increased (during hypercarbic, hypoxic conditions) and absent (postmortem). Cerebral blood flow was measured using the radiolabelled microsphere technique. In the narrow beam studies, cerebral blood flow during baseline was 34 +/- 4 ml/min/100 g, rising to 109 +/- 32 ml/min/100 g during the increased phase (p < 0.001); in the wide beam studies baseline flows were 29 +/- 9 ml/min/100 g, whereas flows in the increased phase were 128 +/- 32 ml/min/100 g (p < 0.001). There was no difference in the heating curves for normal, increased and absent cerebral blood flow for exposure to the narrow beam, when mean temperature increases of 1.5 degrees C at 90 s were recorded in each case (p > 0.21, power > 0.8). However, the heating curves for the wide beam were significantly different for the three rates of blood flow with mean temperature increases of 1.9 degrees C (normal flow), 1.7 degrees C (increased flow) and 2.4 degrees C (no flow) recorded at 90 s (p < 0.05).

Animals↗
PubMed1997

Lag times between blood sampling, spinning and plasma glucose estimation.

This study investigated the effect of lag times between blood sampling and glucose analysis on plasma glucose results from 6 volunteers. Our aim was to determine whether glucose tolerance test protocols should include instructions on the handling of blood between sampling and analysis. Plasma glucose levels remained stable for all lag times between spinning and analysis. With a lag time between blood sampling and spinning, plasma glucose levels did not remain stable, and a significant lowering of plasma glucose was found in the first 2 hours of lag. With increased lag time there was no further decrease in plasma glucose levels. Glucose tolerance test protocols should include clear guidelines on the handling of the blood samples between collection and analysis, and the spinning down of samples needs to be prioritized.

Adult↗
PubMed1995

Systemic bacterial and fungal infections in infants in Australian neonatal units. Australian Study Group for Neonatal Infections.

OBJECTIVE: To examine the pattern and incidence of sepsis occurring in neonatal units in Australia. DESIGN: A one-year prospective study of babies with systemic sepsis within 48 hours of birth (early-onset sepsis) or after this time (late-onset sepsis) in seven Australian neonatal units. Systemic sepsis was defined as clinical sepsis, plus either positive bacterial or fungal culture of blood and/or cerebrospinal fluid, or group B streptococcal antigen detected in the urine. RESULTS: There were 241 episodes of sepsis, affecting 234 babies. One quarter (61) were early-onset, a rate of 2.2 per 1000 live births. Group B streptococcus (GBS) was the commonest cause of early-onset sepsis, with a rate of 1.3 per 1000 live births. The incidence of early-onset GBS sepsis was lower at a hospital which screened for maternal carriage and used intrapartum antibiotic prophylaxis for all carriers. The rate of late-onset sepsis was 4.4 per 1000 live births and coagulase-negative staphylococci were the commonest cause. Meningitis occurred in 23% of babies with early-onset and in 10% with late-onset sepsis. The mortality from early-onset sepsis was 15%, and from late-onset sepsis was 9%. There were no major regional variations, other than for GBS. CONCLUSIONS: The incidence of and mortality from neonatal sepsis is comparable to other countries, and shows no major regional variation. The use of intrapartum antibiotics may reduce the incidence of neonatal GBS sepsis. There are no previous comparable data on neonatal infections in Australia.

Australia↗
PubMed1990

Interference from digoxin-like immunoreactive substance(s) in commercial digoxin kit assay methods.

We have examined the current state of interference by digoxin-like immunoreactive substance(s) (DLIS) in 10 commercially available digoxin assay methods, ie 5 radioimmunoassays (RIA) and 5 non-radioactive immunoassays. Fifty-five specimens of maternal venous blood (30 from third trimester pregnancy and 25 at delivery) and 32 cord samples from their offspring were tested (none of the subjects being medicated with digoxin). The results demonstrated a wide range of DLIS interference with values up to 1.1 micrograms.l-1 being obtained in the cord blood specimens. Of the methods tested the "Coat-a Count" RIA (Diagnostic Products Corporation) and the EMIT column method (Syva) run on the Cobas MIRA (Roche) consistently showed the least interference with respect to all 3 sources of specimens. The Delfia Method (LKB/Wallac) consistently showed the greatest crossreactivity with DLIS. The present study thus demonstrates that DLIS interference persists in several commercial digoxin methods and suggests that the use of data obtained from such methods may compromise patient management.

Blood Proteins↗
PubMed1988

Serial ultraviolet B exposure and serum 25 hydroxyvitamin D response in young adult American blacks and whites: no racial differences.

We tested the hypothesis that repeated whole body suberythemal ultraviolet B (UVB) exposure would result in less increase of serum 25-hydroxyvitamin D (25OHD) concentrations in black compared with white young adults with no significant change or racial differences in serum calciotropic hormones concentrations. Thirteen white and 7 black adults ranging from 22 to 35 years of age were submitted to sequential total body suberythemal doses of UVB (280-315 nm) biweekly for 6 weeks. Initial UVB dose was 5% below the minimal erythemal dose for the most sensitive skin, followed by 10% increase per exposure for 4 weeks. Blood samples were drawn weekly. Baseline 25OHD concentrations were significantly lower in blacks compared to whites, but the increases in serum 25OHD concentrations were similar in both groups; there were no significant differences by sex or age. Serum 24,25-dihydroxyvitamin D [24,25-(OH)2D] concentrations paralleled the serum 250HD response. Mean serum calcium (total and ionized), magnesium, phosphate, alkaline phosphatase, vitamin D binding protein, C-terminal parathyroid hormone, calcitonin, 1,25-dihydroxyvitamin D [1,25-(OH)2D], and osteocalcin concentrations did not differ between blacks and whites at any time. The ratio of the concentration of 1,25-(OH)2D to 25OHD in their serum was initially higher in blacks compared to whites (p less than 0.0001); the ratios decreased to levels similar to whites by the third UVB exposure. We conclude that, in blacks and whites, sequential suberythemal UVB exposure produces similar elevations of serum 25OHD concentrations and unchanged calciotropic hormones concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Vitamin B12 deficiency in a breast fed infant.

We report the case of a 5 month old breast fed infant who presented with a history of vomiting, pallor, and failure to thrive. Investigations showed severe nutritional vitamin B12 deficiency with a megaloblastic pancytopenia. This deficiency was due to low vitamin B12 concentrations in the maternal breast milk, and subsequent investigations showed maternal pernicious anaemia. Treatment of the infant with vitamin B12 resulted in a rapid clinical and haematological improvement. This case represents an unusual presentation of pernicious anaemia.

Anemia, Pernicious↗
PubMed1987

The effect of theophylline on regional cerebral blood flow responses to hypoxia in newborn piglets.

Theophylline attenuates cerebral hypoxic hyperemia in several adult models and this is thought to be due to receptor-mediated antagonism of adenosine, a proposed mediator of hypoxic hyperemia. This attenuation of hypoxic hyperemia reduces cerebral oxygen delivery and may thus jeopardize cerebral oxidative metabolism. With these considerations in mind, and because theophylline is widely used in neonatal medicine, the present study was designed to investigate the effect of theophylline on regional cerebral blood flow, cerebral oxygen delivery, and cerebral metabolic rate for oxygen during normoxia and hypoxia in the newborn piglet model. In 16 newborn piglets, regional cerebral blood flow (microspheres) increased 250-350% during hypoxia (PaO2 20-30 torr), while cerebral oxygen delivery and cerebral metabolic rate for oxygen were maintained at normoxic levels. Eight of these piglets were then given 10 mg/kg theophylline ethylenediamine intravenously and studies during normoxia and hypoxia were repeated; the remaining eight piglets served as time controls. Regional cerebral blood flow, cerebral oxygen delivery, and cerebral metabolic rate for oxygen during normoxia and hypoxia were not influenced by theophylline, despite plasma theophylline levels of 55-65 mumol/liter, and cerebrospinal fluid theophylline levels of 30-40 mumol/liter. These negative results are reassuring with respect to hypoxic cerebral blood flow control in theophylline-medicated infants. However, they do not support a role for adenosine as a mediator of cerebral hypoxic hyperemia in this model.

Animals↗
PubMed1986

Partially ventilated endotracheal suction. Use in newborns with respiratory distress syndrome.

Ventilator adapters that permit endotracheal suction without disconnection from mechanical ventilation may overcome several of the theoretical contributors to the hypoxia and bradycardia associated with neonatal endotracheal suction. Such an adapter allows for partially ventilated endotracheal suction (PVETS) as opposed to traditional, nonventilated endotracheal suction. To test the clinical value of PVETS using an endhole adapter, changes in transcutaneous partial pressure of oxygen and heart rate were compared during paired PVETS and nonventilated endotracheal suction events on 32 occasions in 11 premature neonates with respiratory distress syndrome. Partially ventilated endotracheal suction was associated with a significant decrease in the incidence and severity of hypoxic events. Partially ventilated endotracheal suction, however, did not affect the incidence of bradycardic events; PVETS had a small but statistically significant effect on reducing the severity of bradycardia. No clear relationship between bradycardic and hypoxic events was evident.

Bradycardia↗
PubMed1985

Cerebrovascular hemodynamics during and after recovery from acute asphyxia in the newborn dog.

Cerebrovascular volume and transmural pressure loads accompanying acute increases in cerebral blood flow are implicated in the pathogenesis of periventricular-intraventricular hemorrhage in preterm infants. An acute increase in cerebral blood flow would be expected during acute recovery from asphyxia. Therefore, cerebrovascular hemodynamics, including flow (microspheres), were studied during and after acute recovery from asphyxia in seven newborn dogs in order to study the determinants of these volume and pressure loads. During the acute recovery phase, cerebral hemispheric blood flow was 69.6 +/- 10 ml/100 g/min (mean +/- SEM) representing a 250% increase from baseline values of 19.9 +/- 1.8 ml/100 g/min (p less than 0.005), while combined cerebellar-brainstem flow was 204.3 +/- 19.3 ml/100 g/min representing a 536% increase from baseline values of 32.0 +/- 1.5 ml/100 g/min (p less than 0.005). Blood flow to both areas had returned to baseline levels 20 min after the onset of recovery. Associated with this cerebral hyperemia was an acute increase in mean arterial pressure from 21.3 +/- 4.5 mm Hg at end asphyxia to 69.5 +/- 6.0 mm Hg at peak recovery (p less than 0.01), and parallel acute increases in sagittal sinus pressure (from 4.0 +/- 0.4 to 14.6 +/- 1.9 mm Hg, p less than 0.01) and cerebrospinal fluid pressure (from 3.8 +/- 0.4 to 14.3 +/- 1.9 mm Hg, p less than 0.01). Central venous pressure fell from 4.3 +/- 0.6 mm Hg at end asphyxia to 1.6 +/- 0.5 mm Hg, and thus is not a determinant of the elevation in sagittal sinus pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗