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Biomedical subjects

C O'Callaghan

Publications and source records attributed to C O'Callaghan.

At least 73 records · Page 4Linked to original sources
PubMed1994

The effect of halothane on neonatal ciliary beat frequency.

The effect of a commonly used anaesthetic agent, halothane, on neonatal cilial function was determined. A nasal cilial sample was taken from 13 healthy, term, newborn infants. For 1 h, half of each sample was exposed to halothane and half to air. Cilial function was assessed by measuring beat frequency with a modified light transmission method. Cilial beat frequency was significantly slower in the cilia exposed to halothane, 9(s.d. 2.5)Hz, than to air, 12.9(s.d. 1.5)Hz. Decreased mucociliary clearance following halothane anaesthesia is due, at least in part, to a directly depressant effect of halothane on ciliated cells.

Air↗
PubMed1994

Neonatal platelet reactivity and serum thromboxane B2 production in whole blood: the effect of maternal low dose aspirin.

OBJECTIVES: Concern has been expressed about possible neonatal side effects after the use of maternal anti-platelet agents in pregnancy, particularly low dose aspirin treatment. We have studied neonatal platelet behaviour using whole blood techniques, and assessed the neonatal effect of the maternal ingestion of 60 mg aspirin daily. DESIGN: Cross sectional and randomised, double-blind, placebo-controlled. SETTING: University hospital. SUBJECTS: 1. Eight normal women, studied before conception, and their infants. 2. Twenty-four infants whose mothers had been randomised to receive either 60 mg aspirin daily, or placebo, in double-blind fashion. METHODS: The Clay Adams Ultra Flo 100 whole blood single platelet counter was employed to measure platelet aggregation in response to various agonists. The platelet release reaction was also measured in whole blood, and serum thromboxane B2 (TxB2) production was measured by radio-immunoassay. Umbilical cord blood samples were obtained at delivery. RESULTS: 1. Neonatal platelet aggregation induced by adrenaline, ADP and platelet activating factor was reduced in comparison with their mothers (P < 0.01), whereas the neonatal platelet release reaction was reduced when stimulated by collagen and U46619 (a thromboxane mimetic) (P < 0.01). Serum TxB2 production was similar in mothers and babies. 2. Neonatal platelet aggregation, release reaction and serum TxB2 production were not significantly reduced in infants exposed to maternal aspirin in comparison with those neonates exposed to maternal placebo. This is in contrast to the effect on maternal platelets. CONCLUSIONS: Although only a small number of patients were studied, we interpret this as a relative sparing of neonatal platelet reactivity due to the presystemic action of low dose aspirin.

Adult↗
PubMed1994

Delivery of beclomethasone dipropionate from a spacer device: what dose is available for inhalation?

BACKGROUND: It is common for inhaled steroids to be delivered through a large volume spacer device. Comparatively little is known about how this practice affects the dose of drug received by patients compared with drug delivered directly from a metered dose inhaler. METHODS: The amount of beclomethasone dipropionate, contained in particles of various size, available for inhalation from a 750 ml polycarbonate spacer (Volumatic) was determined by impinger measurement and high performance liquid chromatography. Three strengths of metered dose inhalers were studied (50 micrograms, 100 micrograms, and 250 micrograms/actuation). The effect of multiple actuations of beclomethasone dipropionate into a Volumatic spacer, and increasing residence times of drug within the spacer before inhalation, on the amount of drug available to the patient for inhalation was determined. RESULTS: The amount of beclomethasone dipropionate in particles < 5 microns when delivered by a spacer device or directly from a metered dose inhaler was similar. The total amount of beclomethasone dipropionate available for inhalation per actuation decreased by 20 micrograms with the 50 micrograms inhaler, 48 micrograms with the 100 micrograms inhaler, and 161 micrograms with the 250 micrograms inhaler, when given via the spacer compared with delivery directly from a metered dose inhaler. There was a progressive decrease in drug available for inhalation per actuation as the number of actuations into the spacer increased, for all strengths of beclomethasone dipropionate tested. A progressive decrease in drug recovered per actuation was also seen with increasing residence times of drug within the spacer before inhalation. CONCLUSIONS: Use of the spacer device significantly reduced the amount of nonrespirable beclomethasone dipropionate available for inhalation. The amount of beclomethasone dipropionate within respirable particles decreased considerably following multiple actuations into the spacer and with increasing residence times within the spacer before inhalation. When given via a spacer device beclomethasone dipropionate should be inhaled immediately after actuation and multiple actuations into the device should be avoided.

Beclomethasone↗
PubMed1994

Multiple actuations of salbutamol MDI into a spacer device reduce the amount of drug recovered in the respirable range.

We wanted to determine the amount of salbutamol available in respirable particles from the Volumatic spacer device after one, two or five actuations of a metered-dose inhaler into the spacer prior to analysis. A glass multistage liquid impinger was used to determine particle size. Aerosol was sampled after one, two or five actuations from a metered-dose inhaler into a Volumatic spacer. Each experiment was repeated four times. The amount of salbutamol recovered per actuation in particles less than 5 microns (mean and 95% confidence intervals) was: 54.3 micrograms (48.3-60.1) after one actuation; 42.4 micrograms (38.2-46.5) after two actuations, and 20.7 micrograms (17.5-23.9) after five actuations. We conclude that multiple actuations of salbutamol into the Volumatic spacer do not linearly increase the amount of drug available for inhalation. To maximize drug delivery, single actuations should be used prior to inhalation. In comparative studies of drugs and dosages, it must be remembered that the amount of drug delivered is not the same as that administered.

Administration, Inhalation↗
PubMed1993

Optimum use of a spacer device.

Nedocromil sodium given by the Fisonair spacer should be inhaled immediately. Multiple actuations into the spacer should be avoided. Delay of 20 seconds before sampling reduced the amount of drug available for inhalation in the respirable range by 81%. Placing two actuations into the spacer reduced the amount of drug available by 47%.

Administration, Inhalation↗
PubMed1993

Improvement in sodium cromoglycate delivery from a spacer device by use of an antistatic lining, immediate inhalation, and avoiding multiple actuations of drug.

BACKGROUND: Aerosols generated from metered dose inhalers may be highly charged. The aim of this study was to determine whether lining the walls of a polycarbonate spacer device with an antistatic agent would result in an increase in drug output. The effects of multiple actuations of drug into the spacer device and increasing residence time of drug within the spacer were also determined. METHODS: The amount of sodium cromoglycate contained in particles of various size available for inhalation (per 5 mg actuation) from a 750 ml polycarbonate spacer was determined by impinger measurement and spectrophotometric assay. RESULTS: Lining the spacer with an antistatic agent increased the mean (SD) amount of sodium cromoglycate in particles < 5 microns available for inhalation (per 5 mg actuation) by 244% from (0.59 (0.03) to 1.44 (0.2) mg). When there was a 20 second interval between actuation into the spacer device and inhalation, sodium cromoglycate available for inhalation in particles < 5 micrograms decreased by 67% (from 0.59 (0.03) mg to 0.2 (0.01) mg). Use of the spacer device increased sodium cromoglycate available for inhalation in respirable particles (< 5 microns) by 18% compared with direct delivery by metered dose inhaler. Multiple actuations into the spacer decreased the amount of sodium cromoglycate available for inhalation in particles < 5 microns by 31% after two actuations and 56% after three acutations. CONCLUSIONS: Multiple actuations of sodium cromoglycate into a spacer device before inhalation should be avoided, and inhalation from spacer devices should take place immediately after actuation to ensure maximum dose. Lining of a standard spacer device with an antistatic agent significantly increased output of sodium cromoglycate. This may have implications for improved therapeutic response and drug cost.

Administration, Inhalation↗
PubMed1992

A randomized placebo-controlled study of the effect of low dose aspirin on platelet reactivity and serum thromboxane B2 production in non-pregnant women, in normal pregnancy, and in gestational hypertension.

OBJECTIVE: To investigate the effect of 60 mg aspirin daily on platelet reactivity and prostaglandin production in various groups of patients. Similar regimens, which are thought to act through inhibition of platelet thromboxane production, are currently undergoing clinical assessment for the prevention of pre-eclampsia and intrauterine growth retardation. DESIGN: A prospective randomized placebo controlled study. SETTING: University Hospital, Nottingham. SUBJECTS: 12 non-pregnant female volunteers, 18 normal primigravidae before 16 weeks gestation and 16 pregnant women admitted with gestational hypertension (GH) at a mean gestation of 38 weeks. INTERVENTIONS: In the non-pregnant women blood samples were taken before and after a 10-day course of 60 mg aspirin daily. The primigravidae had blood samples taken at 16 weeks and then they were randomized to receive either 60 mg aspirin daily or a matched placebo. Further blood samples were obtained at 28, 32 and 36 weeks. MAIN OUTCOME MEASURES: Changes in platelet reactivity and release reaction, and serum thromboxane production, were estimated in whole blood. RESULTS: 60 mg aspirin daily significantly inhibited cyclo-oxygenase dependent platelet aggregation, release reaction and serum thromboxane production in non-pregnant and pregnant women, and in women with GH (P less than 0.01). When adrenaline was used as the aggregating agent, the cyclo-oxygenase pathway was recruited in the increased reactivity seen in the third trimester of normal pregnancy, and was sensitive to inhibition by low dose aspirin. CONCLUSION: Low dose aspirin would appear to be an appropriate agent for the inhibition of platelet reactivity associated with hypertensive pregnancy.

Adult↗
PubMed1992

Evaluation of techniques for delivery of steroids to lungs of neonates using a rabbit model.

Little is known about delivery of aerosolised steroids to neonatal patients undergoing assisted positive pressure ventilation and after extubation. A rabbit model has been established to investigate factors influencing drug delivery. Beclomethasone dipropionate, in a metered dose inhaler, was radiolabelled with technetium 99m. The mass median aerodynamic diameter of the aerosol was 3.3 (2.0) microns and the impactor measurements confirmed that the technetium distribution corresponded with that of the drug particles. The metered dose inhaler was actuated into a collapsible spacer that was used to ventilate and deliver aerosol to anaesthetised rabbits by a tracheostomy. From each actuation of the drug 2.9 (0.4)% of the aerosol deposited in the trachea and main bronchi and 1.2 (0.4)% in the lung. When the drug was delivered by a spacer device, with face-mask attachment, to rabbits breathing freely through a tracheostomy, aerosol deposition increased to 4.4 (2.1)% in the trachea and main bronchi and 1.9 (0.9)% in the lung lobes. The maximum change in systolic blood pressure after administration of aerosol by the collapsible spacer was a decrease of 13%. The methods described may prove useful for the delivery of inhaled steroids to neonatal patients likely to develop bronchopulmonary dysplasia.

Administration, Inhalation↗
PubMed1992

Respiratory status and allergy after bronchiolitis.

As part of a long term prospective study, 73 children who had been admitted to hospital with viral bronchiolitis as infants, were reviewed 5.5 years later and compared with a carefully matched control group. In the postbronchiolitis group, there was a highly significant increase in respiratory symptoms including wheezing (42.5% v 15.0%, relative risk = 2.8). Although atopy in the family was not significantly increased in the index group, personal atopy was more prevalent. However, personal atopy was not significantly more prevalent in the symptomatic postbronchiolitis, compared with those who were symptom free, and so did not account for the high prevalence of postbronchiolitis wheezing in this cohort. In addition, in a stepwise logistic regressional model, bronchiolitis remained a significant predictor of wheezing after adjusting for potential confounding variables, including atopy. Bronchial responsiveness to histamine was significantly increased in the index group. However, no significant relationship of positive tests to wheezing could be demonstrated, and a high rate of positive responses was noted in the controls.

Bronchiolitis, Viral↗
PubMed1991

Handwashing and cohorting in prevention of hospital acquired infections with respiratory syncytial virus.

Hospital acquired infections with respiratory syncytial virus are a major problem. The virus is spread predominantly by infected nasal secretions and we investigated whether we could reduce its incidence by cohorting babies on each ward into designated areas and encouraging staff and parents to wash their hands. We examined the incidence of hospital acquired infection due to respiratory syncytial virus in all children less than 2 years old and in those with congenital heart disease. In 1986-7, before any intervention, 18 (4.2%) of 425 hospitalised children less than 2 years old developed hospital acquired infection due to respiratory syncytial virus. In 1987-8, after intervention, five (0.6%) of 840 children developed hospital acquired infection but there were fewer ward admissions with community acquired infections due to the virus. In 1988-9, when there were more community acquired infections than 1986-7, six (1.1%) of 552 children developed hospital acquired infection. In 1986-7, eight (34.8%) of 23 children less than 2 years old with congenital heart disease developed hospital acquired infection due to respiratory syncytial virus; all eight were among 11 children with congenital heart disease hospitalised for more than 14 days. In 1987-8, one (3.3%) of 30 children with congenital heart disease developed hospital acquired infection due to respiratory syncytial virus and in 1988-9 there was one (2.1%) case out of 47 children with congenital heart disease. Handwashing and cohorting significantly reduce the incidence of nosocomial respiratory syncytial virus infection.

Cohort Studies↗
PubMed1991

Ciliary beat frequency in newborn infants.

The ciliary beat frequencies of 31 newborns and 14 adults were measured in vitro by a photodiode method at body temperature (37 degrees C). The mean (SD) neonatal ciliary beat frequency (12.7 (0.82) Hz) was faster than that in adults (11.1 (0.84) Hz) (p less than 0.01). Increased ciliary beat frequency may be advantageous during the neonatal period.

Adult↗
PubMed1991

Nebulised water as a bronchoconstricting challenge in infancy.

The pulmonary response to inhalation challenge with nebulised distilled water was measured in 100 sedated infants with a history of wheeze. Lung function was measured by total body plethysmography. Satisfactory results were obtained in 88 infants. Fifty one were considered to have responded by developing a greater than 20% decrease in specific conductance (sGaw) after nebulised water. Thirty two of these infants had previously been challenged with nebulised saline before but only one showed a greater than 20% decrease in sGaw after saline. Twenty infants who developed signs of bronchoconstriction after challenge with nebulised water were rechallenged 20 minutes later. After the initial challenge a fall in sGaw of greater than 20% was found in 19 of the 20. After a second challenge with nebulised water only 15 (75%) showed a 20% or greater decrease in sGaw. Nine of the 20 infants remained sedated and were rechallenged for a third time. Eight showed a greater than 20% decrease in sGaw. This study indicates that approximately 60% of infants with a history of wheeze will bronchoconstrict in response to inhaled nebulised water and that up to 75% show no evidence of a subsequent refractory period to inhaled water challenge.

Administration, Inhalation↗
PubMed1990

Echo planar imaging of an infant with pectus excavatum.

Echo planar imaging has enabled us to image safely and without sedation the thorax of an infant with pectus excavatum deformity. The heart was displaced into the left side of the thorax, and the right lung was calculated to be 1.6 times larger than the left lung.

Funnel Chest↗
PubMed1990

Improved quality of care and reduction of housestaff workload using trauma nurse practitioners.

The University of California, Davis, Medical Center introduced the use of nurse practitioners (NPs) to the trauma service in fiscal year 1986-87 to alleviate the increasing burdens placed on the surgical housestaff in their attempt to accommodate the rising patient volume and acuity. The use of NPs was associated with a decrease in average length of stay for the seriously injured patients from 8.10 to 7.05 days while the length of stay for other patients in the hospital remained unchanged. Documentation of quality of care in the medical record increased substantially. For example, discharge summaries that were dictated by the NPs were judged complete in all aspects in at least 95% of sampled records compared with approximately 75% of records that were dictated by the residents. With introduction of the NPs, outpatient clinic waiting times decreased from 41 to 19 minutes. Patient complaints regarding the trauma team decreased from 16 to seven/year. Time saved for the housestaff averaged 352 minutes/day while the NPs were on duty. The NPs were well received by the hospital nurses, hospital quality assurance personnel, and ancillary services. They have proved to be of great value to the patients, the patients' families, the hospital, and the trauma team.

California↗
PubMed1990

Estimation of lung volume in infants by echo planar imaging and total body plethysmography.

Echo planar imaging (an extremely fast method of magnetic resonance imaging) was used to measure lung volume in a group of nine infants, all of whom had had respiratory problems. The mean echo planar imaging estimate of total lung volume was 44 +/- 9 ml/kg. In each case the right lung was larger than the left (ratio 52.8:47.2%). The mean thoracic gas volume was 36 +/- 8 ml/kg. The entire sequence of images of the thorax (about 400) takes five minutes to complete, infants require no sedation, and there are no side effects.

Female↗