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Biomedical subjects

D M Campbell

Publications and source records attributed to D M Campbell.

At least 19 recordsLinked to original sources
PubMed2006

Nasal continuous positive airway pressure from high flow cannula versus Infant Flow for Preterm infants.

OBJECTIVE: To compare the feasibility of continuous positive airway pressure (CPAP) support generated by high flow nasal cannula with conventional CPAP for prevention of reintubation among preterm infants with a birth weight of <or=1,250 g. STUDY DESIGN: Preterm infants were randomized to CPAP generated via high flow cannula or the Infant Flow Nasal CPAP System (VIASYS, Conshohocken, PA, USA) at extubation. Primary outcome was incidence of reintubation within 7 days. Secondary outcomes included change in oxygen use and frequency of apnea and bradycardias postextubation. RESULTS: Forty neonates were randomized. Twelve of 20 infants randomized to high flow cannula CPAP were reintubated compared to three of 20 using Infant Flow (P=0.003). The high flow cannula group had increased oxygen use and more apneas and bradycardias postextubation. CONCLUSIONS: CPAP delivered by high flow nasal cannula failed to maintain extubation status among preterm infants <or=1,250 g as effectively as Infant Flow CPAP.

Apnea↗
PubMed2006

Absence of conception after caesarean section: voluntary or involuntary?

BACKGROUND: Women who deliver by caesarean section have been shown to be less likely to have a subsequent pregnancy. It is not clear whether this is due to a direct effect of the procedure on future fertility or due to deliberate avoidance of a future pregnancy. OBJECTIVE: To investigate whether absence of conception following caesarean section is voluntary or involuntary. DESIGN: Follow up of a population-based retrospective cohort. SETTING: Grampian region, Scotland. POPULATION: Women who had no further viable pregnancies within 5 years of an initial delivery. METHODS: Cases included women who delivered their first child by caesarean section between 1980 and 1995 but had no further viable pregnancies by December 2000. Controls included women who delivered their first child during the same period, by means of either spontaneous vaginal delivery (SVD) or instrumental vaginal delivery (IVD), and who had no further viable pregnancies by December 2000. Eligible women were identified from the Aberdeen Maternity and Neonatal Databank (AMND) and sent postal questionnaires to determine the extent to which not conceiving after first delivery was voluntary and the reasons for avoiding further pregnancies. Characteristics of the different mode of delivery groups were compared using univariate techniques. MAIN OUTCOME MEASURES: Extent to which absence of conception following an initial delivery by caesarean section is voluntary. RESULTS: Questionnaires were returned by 3204 (60%) of 5300 women identified from the AMND. Of these, 1675 women had not conceived at all during the follow-up period (median duration = 13 years). Absence of conception was voluntary in 488 (69%; 95% CI 66-73%) women following caesarean section, 340 (71%; 95% CI 67-76%) following SVD and 354 (72%; 95% CI 68-76%) following IVD. Few women considered seeking fertility treatment (caesarean section = 72 [10%], SVD = 50 [11%], IVD = 39 [8%]). Of the women who decided to delay or avoid a further pregnancy, fewer women who delivered by SVD reported that the birth experience influenced their decision (caesarean section = 163 [32%], SVD = 67 [18%], IVD = 136 [35%]; P < 0.001). CONCLUSIONS: Irrespective of mode of delivery, not conceiving following the birth of the first child is mainly voluntary. The experience of the previous birth is one of several factors affecting women's decisions to avoid a subsequent pregnancy.

Adult↗
PubMed2004

Numerical simulation of particle motion in an ultrasound field using the lattice Boltzmann model.

In this paper we investigate the motion of small particles suspended in a fluid through which an ultrasound field is propagating. The application of the lattice Boltzmann model to this problem is considered using a two dimensional model. Particles in an ultrasound field are observed to move with a mean particle motion. Further, the time-averaged force on a fixed cylinder is computed and found to be in good agreement with a theoretical expression for the radiation force. Simulations are performed with a single particle, although the approach can equally be applied for a larger number of particles.

Journal Article↗
PubMed2004

Ponderal index is a poor predictor of in utero growth retardation.

OBJECTIVE: To evaluate the usefulness of ponderal index (PI) and related indices of weight and length in identifying asymmetric growth, body thinness and organ asymmetry associated with IUGR. DESIGN: Cross sectional study. SETTING: Aberdeen Maternity Hospital. POPULATION: The population includes term (>/=37 weeks) singleton live births (n= 53,934) between 1986 and 1996, ultrasound measurements in 2522 pregnancies, 712 unselected term pregnancies in 1979/1980 and stillbirths (24-36 weeks) between 1986 and 1995 where the fetus was diagnosed as suffering from acute (n= 73) or chronic (n= 30) anoxic death. METHODS: The strength of association between direct measures of IUGR and various indices of weight and length was determined by linear and multiple stepwise linear regression. MAIN OUTCOME MEASURES: Weight, length, PI and skinfold thicknesses (triceps, biceps, flank thighs, back) were measured at birth. Abdominal circumference, biparietal diameter and femur length were measured by ultrasound at >/=37 weeks. Ratio of liver, heart and kidney to brain were measured in stillbirths. RESULTS: Weight alone was a better predictor of skinfold thickness, abdominal circumference and the ratio of abdominal circumference to biparietal diameter than weight divided by length raised to the power 1, 2, 3 (PI), 4 or 5. The inclusion of gestational age made little difference to the predictive ability of weight for these full term births. Weight, but not PI, was significantly different between the two groups of stillborn fetuses (chronic and acute), which had significantly different (P < 0.001) organ ratios. CONCLUSION: Body weight alone was a better predictor of anthropometric ratios, organ asymmetry and measures of thinness at birth thought to be associated with IUGR than the PI. The inclusion of a length term generally reduced the predictive ability with the highest powers resulting in the poorest prediction.

Body Weight↗
PubMed2003

Relationship between birth weight and adult lung function: controlling for maternal factors.

BACKGROUND: There is conflicting evidence on the "fetal origins hypothesis" of association between birth weight and adult lung function. This may be due to failure to control for confounding maternal factors influencing birth weight. In the present study access to birth details for adults aged 45-50 years who were documented as children to have asthma, wheezy bronchitis, or no respiratory symptoms provided an opportunity to investigate this association, controlling for maternal factors. METHODS: In 2001 the cohort was assessed for current lung function, smoking status, and respiratory symptoms. Birth details obtained from the Aberdeen Maternity and Neonatal Databank recorded birth weight, gestation, parity, and mother's age and height. RESULTS: 381 subjects aged 45-50 years were traced and tested for lung function; 323 (85%) had birth details available. A significant linear trend (p<0.01) was observed between birth weight and current forced expiratory volume in 1 second (FEV(1)) and forced vital capacity (FVC) values (adjusted for height, age, sex, weight, deprivation category (Depcat), childhood group, and smoking status). This trend remained significant after adjusting birth weight for gestation, parity, sex, mother's height and weight (p = 0.01). The relationship between birth weight and FEV(1) and FVC remained significant when adjusted for smoking history. There was no association between birth weight and current wheezing symptoms. CONCLUSION: There is a positive linear trend between birth weight, adjusted for maternal factors, and lung function in adulthood. The strength of this association supports the "fetal origins hypothesis" that impairment of fetal growth is a significant influence on adult lung function.

Adult↗
PubMed2002

Prothrombotic genotypes are not associated with pre-eclampsia and gestational hypertension: results from a large population-based study and systematic review.

DNA samples collected as part of a large population-based case-control study were genotyped to examine the associations of five prothrombotic gene polymorphisms with pre-eclampsia (PE) and gestational hypertension (GH). The polymorphisms studied were: G1691A in Factor V (Factor V Leiden; FVL), prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T, plasminogen activator inhibitor-1 4G/5G and the platelet collagen receptor alpha2beta1 C807T. A group of 404 women who developed PE were retrospectively compared with 303 women with GH and 164 control women. The frequency of genotypes did not differ significantly between cases of PE or GH and controls for any of the five polymorphisms studied. We conclude that these prothrombotic genotypes are not associated with the development of PE or GH in our population. The systematic review supports our conclusion, for all but cases of severe disease. which appear to be associated with FVL and, to a lesser extent, MTHFR C677T. There is little value in antenatal screening for prothrombotic polymorphisms to predict the development of pre-eclampsia or gestational hypertension.

3' Untranslated Regions↗
PubMed2001

Risk factors for sporadic cases of Escherichia coli O157 infection: the importance of contact with animal excreta.

To determine environmental risk factors for sporadic E. coli O157 infection in Scotland we undertook a prospective, matched case-control study between 1 October 1996 and 31 March 1999. One hundred and eighty-three cases and 545 matched controls were recruited. Contact with animal faeces (OR = 3.65; 95% CI 1.81, 7.34: P < 0.0005) and likely contact with animal faeces (OR = 4.8; 95% CI 2.42, 9.48; P < 0.0005) emerged as strong risk factors for infection. Certain exposures (mainly food-related) were inversely associated with infection i.e. were statistically protective. Most striking was the consumption of bottled water (OR = 0.28; 95% CI 0.15, 0.52; P < 0.0005). Transmission of E. coli O157 does not occur simply through contaminated food. Members of the public need to be aware of the potential for acquiring E. coli O157 through contamination of the environment with animal faeces so that they may take measures to mitigate their risk.

Adolescent↗
PubMed2001

Can obstetric complications explain the high levels of obstetric interventions and maternity service use among older women? A retrospective analysis of routinely collected data.

OBJECTIVE: To determine whether the higher levels of obstetric intervention and maternity service use among older women can be explained by obstetric complications. DESIGN: A retrospective analysis of routinely collected data from the Aberdeen Maternity and Neonatal Databank. PARTICIPANTS: All residents of Aberdeen city district delivering singleton infants at the Maternity Hospital 1988-1997 (28,484 deliveries). MAIN OUTCOME MEASURES: Odds ratios for each intervention in older maternal age groups compared with women aged 20-29. Interventions considered include obstetric interventions (induction of labour, augmentation, epidural use, assisted delivery, caesarean section) and raised maternity service use (more than two prenatal scans, amniocentesis, antenatal admission to hospital, admission at delivery of more than five days, infant resuscitation, and admission to the neonatal unit). METHODS: Logistic regression was used to investigate the association between maternal age and the incidence of interventions. The odds ratios for each intervention were then adjusted for relevant obstetric complications and maternal socio-demographic characteristics. RESULTS: Levels of amniocentesis, caesarean section, assisted delivery, induction, and augmentation (in primiparae) are all higher among older women. Maternity service use also increases significantly with age: older women are more likely to have an antenatal admission, more than two scans, a hospital stay at delivery of more than five days, and have their baby admitted to a neonatal unit. Controlling for relevant obstetric complications reveals several examples of effect modification, but does not eliminate the age effect for most interventions in most groups of women. CONCLUSIONS: Higher levels of intervention among older women are not explained by the obstetric complications we considered.

Adult↗
PubMed2001

Assessment of hand-arm vibration syndrome in a northern Ontario base metal mine.

The objective of this study was to determine the prevalence of hand-arm vibration syndrome (HAVS) in 617 workers at a base metal mine in northern Ontario. Workers who were employed at the mine between the years 1989 and 1994 and who continued to live within a 100 km radius of the mine were sent a self-reported questionnaire to identify individuals with possible vibration-induced symptoms in their upper extremities. Of the 162 workers who attended the medical examination, 50% were diagnosed with HAVS, 26% had other diagnoses with some workers having multiple afflictions e.g., both HAVS and carpal tunnel syndrome (CTS). No vibration-induced symptoms were reported in 35% of the workers who were clinically normal. The study was designed to educate, advise, and to make recommendations on the prevention of HAVS. Ongoing commitments to technological improvements, mandatory and regular rest periods, and continuing educational sessions on the syndrome should help to reduce the prevalence of this disease.

Adult↗
PubMed2000

Underlying causes of recurrent pneumonia in children.

OBJECTIVES: To determine the relative frequency of underlying factors for recurrent pneumonia and the proportion of patients in whom the underlying illness diagnosis was known prior to pneumonia recurrence. METHODS: Retrospective medical record review for a 10-year period from January 1987 through December 1997 at The Hospital for Sick Children in Toronto, Ontario, a tertiary care pediatric hospital. Recurrent pneumonia was defined as at least 2 pneumonia episodes in a 1-year period or at least 3 during a lifetime. RESULTS: Of 2952 children hospitalized with pneumonia, 238 (8%) met criteria for recurrent pneumonia. An underlying illness diagnosis was identified in 220 (92%). Of these, the underlying illness was diagnosed prior to pneumonia in 178 (81%), with the first episode in 25 (11%), and during recurrence in 17 (8%). Underlying illnesses included oropharyngeal incoordination with aspiration syndrome (114 cases [48%]), immune disorder (24 [10%]), congenital cardiac defects (22 [9%]), asthma (19 [8%]), pulmonary anomalies (18 [8%]), gastroesophageal reflux (13[5%]), and sickle cell anemia (10 [4%]). Clinical clues to diagnosis were recurrent infections at other locations and failure to thrive in the cases of an immune disorder, recurrences involving the same location in those with underlying pulmonary pathology, the association of respiratory symptoms with feeding in those with gastroesophageal reflux, or recurrent wheezing in asthmatic children. CONCLUSIONS: Recurrent pneumonia occurs in fewer than one tenth of all children hospitalized with pneumonia. Most of them have a known predisposing factor. The most common cause was oropharyngeal incoordination.

Adolescent↗
PubMed2000

The effect of timing of intravenous muscle relaxant on the quality of double-contrast barium enema.

AIM: To determine whether the timing of buscopan administration during double-contrast barium enema examination (DCBE) affects diagnostic quality. MATERIALS AND METHODS: In a prospective setting, 100 consecutive adult out-patients referred for DCBE received 20 mg buscopan (hyoscine-N-butylbromide) intravenously, either before infusion of barium suspension (Group A) or after barium infusion and gas insufflation (Group B). A subjective assessment of ease of contrast medium infusion was made at the time of examination and the films subsequently analysed by two radiologists unaware of the mode of relaxant administration, who noted the quality of mucosal coating and made subjective and objective measurements of segmental distension. RESULTS: There was no significant difference in screening times, infusion difficulty or colonic contrast medium coating between the two groups. Subjective assessment of distension of the caecum, ascending colon, transverse colon and rectum were not significantly different. Patients receiving intravenous relaxant after barium and gas infusion had less subjective descending (P = 0. 05) and sigmoid (P = 0.04) colon distension, but there was no significant difference with respect to maximal bowel diameter in any of the segments measured. CONCLUSION: The timing of intravenous administration during DCBE is likely to have no significant effect on the diagnostic quality of the study.

Adult↗
PubMed2000

Diet in late pregnancy and glucose-insulin metabolism of the offspring 40 years later.

OBJECTIVE: To determine how diets of women in pregnancy influence the glucose-insulin metabolism of their offspring in adult life. DESIGN: A follow up study of men and women born during 1948-1954 whose mothers had taken part in a survey of diet in late pregnancy. SETTING: Aberdeen, Scotland. POPULATION: One hundred and sixty-eight men and women born in the Aberdeen Maternity Hospital. MAIN OUTCOME MEASURE: Plasma glucose and insulin concentrations, fasting and after a standard oral glucose challenge. RESULTS: The offspring of women who had high intakes of fat and protein in late pregnancy had a reduced plasma insulin increment between fasting and 30 min with a 7.0% decrease in increment (P = 0.007) per 10 g increase in protein intake and a 4.9% decrease (P = 0.002) per 10 g increase in fat intake. This was independent of the mother's body mass index or weight gain in pregnancy. A low maternal body mass index in early or late pregnancy was associated with a raised fasting plasma insulin concentration with a decrease of 2.4% (P = 0.05) per 1 kg/m2 increase of maternal body mass. CONCLUSION: High intakes of protein and fat during pregnancy may impair development of the fetal pancreatic beta cells and lead to insulin deficiency in the offspring. The offspring of thin mothers tend to be insulin resistant.

Adult↗
PubMed2000

The effect of smoking on pre-eclampsia in twin pregnancy.

OBJECTIVE: To assess the effect of smoking on the incidence of pre-eclampsia and on perinatal outcome in twin pregnancy. DESIGN: Retrospective study using Aberdeen Maternity and Neonatal Databank. SETTING: Grampian, Orkney and Shetland. POPULATION: All 1,575 twin pregnancies delivered in the years 1969-1971 and 1976-1997 (when smoking data were available). METHODS: In all twin pregnancies the effects of smoking on pre-eclampsia were analysed by parity and gestation at delivery. The effect of smoking upon late miscarriage and perinatal outcome was analysed without subdivision. MAIN OUTCOME MEASURES: Pre-eclampsia and perinatal outcome. RESULTS: Primiparae had significantly higher rates of pre-eclampsia than multiparae and were delivered significantly earlier. The incidence of pre-eclampsia in smokers was significantly lower only in multiparae. Length of gestation was significantly shorter in multiparous smokers. The effect of smoking on pre-eclampsia appeared to be direct in multiparae but possibly indirect in primiparae (by causing earlier delivery). Smokers had a higher late miscarriage rate than nonsmokers. CONCLUSIONS: In twin pregnancy the apparent protective effect of smoking against pre-eclampsia is significant only in multiparae, suggesting that in primiparae the smoking effect is overwhelmed by the other reasons for the development of pre-eclampsia. Smoking in twin pregnancy is not recommended due to the worse fetal outcome rates.

Female↗
PubMed2000

Cyclophosphamide and water retention: mechanism revisited.

We describe an 8 year-old girl with established diabetes insipidus who developed cyclophosphamide-associated antidiuresis. The patient had received cyclophosphamide as part of a high-dose chemotherapy regimen for recurrent suprasellar dysgerminoma prior to autologous bone marrow transplantation. Urinary output decreased and specific gravity increased shortly after a 1 hour i.v. infusion of 50 mg/kg cyclophosphamide and the effect lasted some 5 hours. No other drug could be implicated. This response, occurring in a patient with no ability to secrete vasopressin, suggests a direct tubular effect of one or more cyclophosphamide metabolites. Administering i.v. cyclophosphamide requires careful monitoring of fluid balance in order to avoid water intoxication. Further research is warranted both into the mechanism of this effect and the metabolite responsible for it.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

The use of 0.25% isoflurane premixed in 50% nitrous oxide and oxygen for pain relief in labour.

The addition of 0.25% isoflurane to 50% nitrous oxide in oxygen provides more effective pain relief in labour than 50% nitrous oxide alone. This study was carried out to determine whether self-administration by demand valve of 0.25% isoflurane in 50% nitrous oxide in oxygen premixed in cylinders at 13.7 MPa (IN2O) was practical and safe during labour. Two hundred and twenty-one mothers used IN2O in labour after 50% nitrous oxide had become inadequate for pain relief. Data on IN2O use was recorded during labour and details of the course of labour and opioid usage were taken from the clinical notes. The duration of IN2O use was 0.1-12.35 h (median 2.3). Thirty-two mothers (14.5%) required an epidural and intolerance to IN2O was seen in a maximum of 17 cases (7.7%). One hundred and twenty-six cases were primiparous and 93 parous with 151 deliveries being spontaneous and 70 interventional, of which 12 were by Caesarean section. Maternal blood loss was 20-1500 ml (median 200 ml). Apgar scores at 1 and 5 min were unaffected by IN2O use although a positive correlation was found between the use of opioids and the number of neonates with a 1-min score below 8 and the number requiring resuscitation. Six neonates had an Apgar score below 8 at 5 min, but their condition was adequately explained by factors other than the sedative technique used. Self-administered IN2O was found to be a safe and practical technique for sedation in labour when 50% nitrous oxide alone had become inadequate.

Adolescent↗