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Biomedical subjects

Gerrard F Rafferty

Publications and source records attributed to Gerrard F Rafferty.

At least 19 recordsLinked to original sources
PubMed2007

Temporal relationship of asthma to acute chest syndrome in sickle cell disease.

Acute chest syndrome (ACS) is an important cause of mortality and morbidity in children with sickle cell disease (SCD). An association between asthma and ACS has been reported. Our aims were to determine whether asthma was more common in SCD children than controls and the relationship of the timing of the SCD children's first ACS episode to a diagnosis of asthma. One hundred and sixty-five SCD children median age 8.2 (range 0.3-17.3) years and 151 similar ethnic origin and aged controls were prospectively recruited into the study and a detailed history was taken from all of the children to determine if they were taking anti-asthma medication. The medical records of the SCD children were examined to assess whether they had an ACS episode, the age this episode occurred and when any diagnosis of asthma had been made. A similar proportion of the SCD children and controls were taking anti-asthma medication (7% and 9%). Thirty-three SCD children had at least one ACS episode. More of the children who had an ACS compared to those who had not were taking anti-asthma medication (P = 0.02). The ACS children had been diagnosed as asthmatic at a median of 3.5 (range 0.5-7) years prior to their first ACS episode. In conclusion, these results suggest asthma exacerbations may predispose to ACS episodes.

Acute Disease↗
PubMed2007

Lung function and exhaled nitric oxide levels in infants developing chronic lung disease.

Chronic lung disease (CLD) is a common outcome of neonatal intensive care. To determine whether the results of serial exhaled nitric oxide (eNO) measurements during the perinatal period differed between infants who did and did not develop CLD. In addition, we wished to assess whether eNO results were more predictive of CLD development than lung function test results or readily available clinical data (gestational age and birthweight). The patients were 24 infants with a median gestational age of 27 (range 25-31) weeks. Measurements of eNO levels, functional residual capacity (FRC), and compliance of the respiratory system (CRS) were attempted on postnatal days 1, 3, 5, 7, 14, and 28 days. The 12 infants who developed CLD were of significantly lower birthweight and gestational age than the rest of the cohort; in addition, they had lower median FRC (P < 0.02) and CRS (P < 0.02) results, but not higher eNO levels, in the first week after birth. Construction of receiver operator characteristic (ROC) curves demonstrated that the CRS and FRC results on Day 3 were the best predictors of CLD development; the areas under the ROC curves were 0.94 and 0.91, respectively. Early lung function test results, but not eNO levels, are useful in predicting CLD development, but are not significantly better than birthweight.

Birth Weight↗
PubMed2006

Survey of sleeping position recommendations for prematurely born infants on neonatal intensive care unit discharge.

INTRODUCTION: Prematurely born infants are at an increased risk of sudden infant death syndrome (SIDS), particularly when sleeping prone. Parents are strongly influenced in their choice of sleeping position for their infant by practitioners. The aim of this study was to determine the neonatal units' recommendations regarding the sleeping position for premature infants prior to and after discharge and ascertain whether there had been changes from those recorded in a survey performed in 2001-2002. MATERIALS AND METHODS: A questionnaire survey was sent to all 229 neonatal units in the United Kingdom; 80% responded. RESULTS AND DISCUSSION: The majority (83%) of units utilized the supine sleep position for infants at least 1-2 weeks prior to discharge, but after discharge, only 38% of the units actively discouraged prone sleeping and 17% additionally recommended side sleeping. Compared to the previous survey, significantly more units started infants with supine sleeping 1-2 weeks prior to discharge (p < 0.0001) and fewer recommended side sleeping after discharge (p = 0.0015). However, disappointingly, less actively discouraged prone sleeping after discharge (p = 0.0001). CONCLUSION: Recommendations regarding sleeping position for prematurely born infants after neonatal discharge by some practitioners remain inappropriate. Evidence-based guidelines are required as these would hopefully inform all neonatal units' recommendations.

Adult↗
PubMed2006

Sleeping position, oxygen saturation and lung volume in convalescent, prematurely born infants.

OBJECTIVE: To determine whether the effects of sleeping position on lung volume and oxygenation are influenced by postmenstrual age (PMA) and oxygen dependency in convalescent prematurely born infants. DESIGN: Prospective study. SETTING: Tertiary neonatal unit. PATIENTS: 41 infants (21 oxygen dependent), median gestational age 28 weeks (range 24-31 weeks) and birth weight 1120 g (range 556-1780 g). INTERVENTION: Infants were studied both supine and prone at two-weekly intervals from 32 weeks' PMA until discharge. Each posture was maintained for 1 h. MAIN OUTCOME MEASURES: Pulse oximeter oxygen saturation (Spo(2)) was monitored continuously, and at the end of each hourly period functional residual capacity (FRC) was measured. RESULTS: Overall, lung volumes were higher in the prone position throughout the study period; there was no significant effect of PMA on lung volumes. Overall, Spo(2) was higher in the prone position (p = 0.02), and the effect was significant in the oxygen-dependent infants (p = 0.03) (mean difference in Spo(2) between prone and supine was 1.02%, 95% CI 0.11% to 1.92%), but not in the non-oxygen-dependent infants. There was no significant influence of PMA on Spo(2). CONCLUSION: In the present study, prone sleeping did not improve oxygenation in prematurely born infants, 32 weeks' PMA or older and with no ongoing respiratory problems. However, the infants were monitored in each position for an hour, thus it is recommended that oxygen saturation should continue to be monitored after 32 weeks' PMA to be certain that longer periods of supine sleeping are not associated with loss of lung volume and hypoxaemia.

Functional Residual Capacity↗
PubMed2006

Impact of acute chest syndrome on lung function of children with sickle cell disease.

OBJECTIVE: To test the hypothesis that children with sickle cell disease (SCD) who experienced an acute chest syndrome (ACS) hospitalization episode would have worse lung function than children with SCD without ACS episodes. STUDY DESIGN: Forced expiratory volume in 1 second (FEV(1)); forced vital capacity (FVC); FEV(1)/FVC ratio; peak expiratory flow (PEF); forced expiratory flow at 25% (FEF(25)), 50% (FEF(50)), and 75% (FEF(75)) of FVC; airway resistance (Raw); and lung volumes were compared in 20 children with ACS and 20 aged-matched children without ACS (median age, 11 years; range, 6 to 16 years). Fourteen age-matched pairs were assessed before and after bronchodilator use. RESULTS: The mean Raw (P = .03), TLC (P = .01), and RV (P = .003) were significantly higher in the group with ACS than in the group without ACS. There were no significant differences in the changes in lung function test results in response to bronchodilator administration between the 2 groups, but the children with ACS had a lower FEF(25) (P = .04) and FEF(75) (P = .03) pre-bronchodilator use and a lower mean FEV(1)/FVC ratio (P = .03) and FEF(75) (P = .03) post-bronchodilator use. CONCLUSIONS: Children with SCD who experienced an ACS hospitalization episode had significant differences in lung function compared with those who did not experience ACS episodes. Our results are compatible with the hypothesis that ACS episodes predispose children to increased airway obstruction.

Acute Disease↗
PubMed2006

Effect of prone and supine position on sleep, apneas, and arousal in preterm infants.

OBJECTIVE: Prematurely born compared with term born infants are at increased risk of sudden infant death syndrome, particularly if slept prone. The purpose of this work was to test the hypothesis that preterm infants with or without bronchopulmonary dysplasia being prepared for neonatal unit discharge would sleep longer and have less arousals and more central apneas in the prone position. METHODS: This was a prospective observational study in a tertiary NICU. Twenty-four infants (14 with bronchopulmonary dysplasia) with a median gestational age of 27 weeks were studied at a median postconceptional age of 37 weeks. Video polysomnographic recordings of 2-channel electroencephalogram, 2-channel electro-oculogram, nasal airflow, chest and abdominal wall movements, limb movements, electrocardiogram, and oxygen saturation were made in the supine and prone positions, each position maintained for 3 hours. The duration of sleep, sleep efficiency (total sleep time/total recording time), and number and type of apneas, arousals, and awakenings were recorded. RESULTS: Overall, in the prone position, infants slept longer, had greater sleep efficiency (89.5% vs 72.5%), and had more central apneas (median: 5.6 vs 2.2), but fewer obstructive apneas (0.5 vs 0.9). The infants had more awakenings (9.7 vs 3.5) and arousals per hour (13.6 vs 9.0) when supine. There were similar findings in the bronchopulmonary dysplasia infants. CONCLUSIONS: Very prematurely born infants studied before neonatal unit discharge sleep more efficiently with fewer arousals and more central apneas in the prone position, emphasizing the importance of recommending supine sleeping after neonatal unit discharge for prematurely born infants.

Arousal↗
PubMed2005

Problems in the measurement of functional residual capacity.

Accurate assessment of lung volume in infancy is important to determine the impact of disease and the efficacy of therapies. A new generation of infant plethysmographs with lower apparatus deadspace has been produced, but gives lower volume results than those from older traditional plethysmographs. We hypothesized that the new plethysmographs might have greater sensitivity to the adiabatic effect and hence they, rather than the traditional plethysmographs, produced erroneous results. Our aim was to assess the influence of the adiabatic effect on the results of a contemporary plethysmograph, an older traditional plethysmograph and a helium gas dilution system using a lung model. Altering the amount of copper wool within the lung model allowed the influence of the adiabatic effect on the plethysmographic results to be assessed. The measured compared to the actual volumes were significantly lower for the contemporary plethysmograph compared to the traditional plethysmograph (p < 0.001) and to the helium gas dilution system (p < 0.001). Under optimal testing conditions the contemporary plethysmograph under-recorded by 11-13%, whereas the other two systems gave similar results to the actual volumes. As the effect of the adiabatic effect was increased, the discrepancy between the results of the contemporary and the traditional plethysmographs increased. We conclude, the contemporary plethysmograph is more sensitive to adiabatic effects and hence under-records.

Functional Residual Capacity↗
PubMed2005

Lung volumes in infants who had mild to moderate bronchopulmonary dysplasia.

"New" bronchopulmonary dysplasia (BPD) has been suggested to be a maldevelopment sequence with reduced alveolarisation of the lungs; affected infants then would be predicted to have low lung volumes. The aim of this study was to test that hypothesis by comparing the lung volumes of infants who had had mild-moderate BPD with those without BPD of similar postmenstrual age. Lung volumes of 17 infants who had mild-moderate BPD (oxygen dependent beyond 28 days, but not past term) (BPD infants) were compared to those of 17 infants without BPD (non-BPD infants). All were born at less than 33 weeks of gestation and studied at postmenstrual ages of 33 to 39 weeks. Lung volume was assessed by measurement of functional residual capacity (FRC). The BPD infants had lower lung volumes (median 19.1 ml/kg) than the non-BPD infants (median 26.5 ml/kg) (p = 0.0001). The BPD compared to the non-BPD infants were of greater postnatal age (p = 0.0003), born at a lower gestational age (p = 0.0001) and of lighter birthweight (p = 0.0001). Regression analysis, however, demonstrated that lung volume was significantly related to BPD status (p = 0.005), independently of postnatal age, birthweight and gestational age. It is concluded that the lower lung volumes of the infants who had had mild-moderate BPD support the hypothesis that new BPD is associated with poor alveolarisation.

Birth Weight↗
PubMed2005

Twitch airway pressure elicited by magnetic phrenic nerve stimulation in anesthetized healthy children.

Children with diaphragm dysfunction may be unable to maintain adequate ventilation. Accurate diagnosis is important, but can only be achieved using an appropriate test and reference range. The aim of this study, therefore, was to measure diaphragm contractility and examine the influence of age and maturation, using magnetic phrenic nerve stimulation in healthy children. Anterolateral magnetic stimulation (MS) of the phrenic nerves was performed using a 43-mm figure-eight coil in 23 children (14 male; mean age, 7.8 years; range, 1.8-15.7) anesthetized for minor surgery with sevoflurane gas. The airway was maintained with a cuffed laryngeal mask airway (LMA) which was briefly occluded during MS. Diaphragm contractility was assessed by measuring the airway pressure (TwPaw) elicited by MS. TwPaw responses were obtained in all subjects, with mean (SD) TwPaw 18.2 (6.8) cm H2O bilateral, 7.3 (3.2) cm H2O left unilateral, and 8.6 (3.1) cm H2O right unilateral. Subgroup analysis was performed in 17 of the children who were prepubertal. Their mean (SD) TwPaw was 17.3 (6.8) cm H2O bilateral, 7.1 (3.7) cm H2O left unilateral, and 8.3 (3.3) right unilateral. The mean (SD) intrapatient coefficients of variation for bilateral and left and right unilateral TwPaw were 8.4% (5.2), 6.7% (3.5), and 11.7% (10.3), respectively. Bilateral and left and right unilateral TwPaw were significantly related to age (P < 0.05). In healthy prepubertal children, diaphragm contractility is primarily influenced by age.

Adolescent↗
PubMed2005

Lung volumes in healthy Afro-Caribbean children aged 4-17 years.

Lung volumes in healthy children differ according to their ethnic origin. We wished to determine if any differences in the lung volumes of Afro-Caribbean (AC) children from those predicted by Caucasian reference values disappeared if the results were related to sitting height or to 90% or 77% of lung volumes predicted for height from Caucasian reference values based on standing height. We took, as our working hypothesis, that it is inappropriate to use Caucasian reference values to interpret data from Afro-Caribbean children, and that ethnic-specific reference values are required. This was a prospective, observational study. Subjects included 80 AC children with a median age of 9 (range, 4.3-17.8) years. Standing and sitting height were measured. Lung volumes were measured by body plethysmography (total lung capacity, TLC(pleth); functional residual capacity, FRC(pleth); and vital capacity, VC(pleth)), helium gas dilution (functional residual capacity, (FRC(He)), spirometry (forced expiratory volume in 1 sec, FEV(1)), and forced vital capacity (FVC). The lung volumes of AC children correlated significantly with standing height, but differed significantly from values predicted from Caucasian reference values based on standing height (P < 0.05). Significant differences remained for TLC(pleth), FRC(pleth), FRC(He), RV(pleth), VC(pleth), FEV(1), and FVC when the results were related to sitting height or 90% or 77% of values predicted from Caucasian reference values based on height (P < 0.05). Lung volumes in Afro-Caribbean children should be compared to ethnic-specific reference values.

Adolescent↗
PubMed2004

Exhaled carbon monoxide levels in children with sickle cell disease.

UNLABELLED: It is important to measure the rate of haemolysis in patients with sickle cell disease (SCD) to identify aplastic crises and indirectly assess the rate of vaso-occlusion and sequestration. The aim of this study was to assess whether end-tidal carbon monoxide (ETCOc) levels in children with sickle cell disease (SCD) could be measured reproducibly, reflected haemolysis and whether they were elevated compared to those of similarly aged, ethnic matched children without SCD (controls). ETCOc levels were measured non-invasively in 87 SCD children (age range 2.3-17.6 years) and 26 age and ethnic origin matched healthy controls using an electro-chemical sensor. The within- and between- occasion reproducibilities were assessed in ten and 15 SCD children respectively. ETCOc levels of 15 SCD children undergoing regular transfusions were related to carboxyhaemoglobin, haemoglobin and bilirubin levels. The within and between occasions' mean intrasubject coefficients of reproducibility were 5% and 18% respectively. Positive correlations were found between the ETCOc and carboxyhaemoglobin ( P =0.007) and bilirubin ( P =0.02) levels, and a significant negative correlation between the ETCOc and haemoglobin ( P =0.0002) levels. The mean and SD ETCOc levels of the SCD children (4.9 ppm; SD 1.7 ppm) were significantly higher than that of the controls (mean 1.3 ppm; SD 0.4 ppm) (difference between means 3.60; 95% C.I. 2.93-4.28; P <0.0001). CONCLUSION: These results suggest that measurement of end-tidal carbon monoxide levels is a reliable and useful method to monitor haemolysis in children with sickle cell disease.

Adolescent↗
PubMed2004

Exhaled nitric oxide levels in infants with chronic lung disease.

UNLABELLED: Chronic lung disease (CLD) is an inflammatory disorder; in patients with other inflammatory disorders exhaled nitric oxide (NO) levels are elevated. The aim of this study was to test the hypothesis that prematurely born infants with CLD would have elevated exhaled NO levels compared to those without CLD and healthy term-born infants. Ten infants with CLD (median gestational age 26 weeks; CLD group), ten infants without CLD (median gestational age 32 weeks; non-CLD group) and ten term-born infants (term group) were examined at post-conceptional ages between 36 and 45 weeks. NO levels were measured during spontaneous tidal breathing. A facemask was positioned over the infant's nose and mouth and a sampling catheter was inserted through a small leak-free valve into the facemask. To measure nasal NO, the tip of the sampling catheter was placed in the nasal space and to measure facemask NO, the catheter tip was positioned inside the facemask at the infant's lips. Nasal compared to facemask NO levels were higher in all three groups (CLD; non-CLD; term: P=0.017, P=0.012 and P=0.017, respectively). The CLD group had higher peak nasal and facemask NO levels than the non-CLD ( P=0.011 and P=0.034 respectively) and the term ( P=0.005 and P=0.01 respectively) infants. Regression analysis demonstrated that facemask NO levels were significantly related to CLD, independent of gestational, post-natal and post-conceptional age ( P=0.006). CONCLUSION: our results suggest that exhaled nitric oxide levels are elevated in chronic lung disease infants. Facemask measurement of nitric oxide levels might be a potentially useful method to monitor infants with chronic lung disease.

Case-Control Studies↗
PubMed2003

Pulmonary function at follow-up of very preterm infants from the United Kingdom oscillation study.

Prematurely born infants supported by conventional ventilation (CV) frequently have abnormal pulmonary function when assessed in childhood. The aim of this study was to test the hypothesis that infants who were randomly assigned to high-frequency oscillatory ventilation would have superior pulmonary function at follow-up compared with those who received CV (UK Oscillation Study). Infants from 12 trial centers were recruited for pulmonary function testing at a single center. Seventy-six infants, of a mean gestational age 26.4 weeks, were studied after sedation with chloral hydrate at between 11 and 14 months of age, corrected for prematurity. Infants assigned to CV had similar pulmonary function compared with those assigned to high-frequency oscillatory ventilation, with mean (SD) results as follows: functional residual capacity measured by whole-body plethysmography, 26.9 (6.3) versus 26.5 (6.4) ml/kg; functional residual capacity measured by helium dilution, 24.1 (5.4) versus 23.5 (5.7) ml/kg; inspiratory airway resistance, 3.3 (1.3) versus 3.4 (1.6) kPa. second. L; expiratory airway resistance, 4.4 (2.8) versus 4.1 (2.5) kPa. second. L; respiratory rate, 31.2 (6.0) versus 33.9 (8.0) breaths/minute. We conclude that early use of high-frequency oscillatory ventilation in very preterm infants appears to offer no advantage over CV in terms of pulmonary function at follow-up.

Bronchopulmonary Dysplasia↗
PubMed2003

Cough gastric pressure and maximum expiratory mouth pressure in humans.

Maximal expiratory mouth pressure is a well established test that is used to assess expiratory muscle strength. However, low values are difficult to interpret, as they may result from technical difficulties in performing the test, particularly in patients with facial muscle weakness or bulbar dysfunction. We hypothesized that measuring the gastric pressure during a cough, a natural maneuver recruiting the expiratory muscles, might prove to be a useful additional test in the assessment of expiratory muscle function. Mouth expiratory and cough gastric pressures were measured in 99 healthy volunteers to obtain normal values and in 293 patients referred for respiratory muscle assessment to compare the two measurements. Between-occasion within-subject coefficient of variation, assessed in 24 healthy volunteers, was 10.3% for mouth pressure and 6.9% for cough. Mean +/- SD cough gastric pressure for normal males was 214.4 +/- 42.2 and 165.1 +/- 34.8 cm H2O for females. In 171 patients deemed weak by a low mouth expiratory pressure, 42% had a normal cough gastric pressure. In 105 patients deemed weak by a low cough gastric pressure, 5.7% had a normal expiratory mouth pressure. Low maximal expiratory mouth pressures do not always indicate expiratory muscle weakness. Cough gastric pressure provides a useful complementary test for the assessment of expiratory muscle strength.

Case-Control Studies↗
PubMed2003

Symptoms and quadriceps fatigability after walking and cycling in chronic obstructive pulmonary disease.

Patients with chronic obstructive pulmonary disease (COPD) may stop cycling due to leg effort rather than breathlessness. However, cycling is not relevant to many patients, although walking may be more familiar. A total of 84 patients with COPD were asked to name the predominant symptom limiting incremental shuttle walking, endurance shuttle walking, incremental cycle ergometry, and endurance cycle ergometry, performed to exhaustion on four separate days. Furthermore, quadriceps fatigability was evaluated in 12 patients by measuring unpotentiated and potentiated twitch quadriceps tensions before and 30 minutes after incremental walking and cycling. Breathlessness alone was a more commonly cited limiting symptom after incremental walking compared with incremental cycling (81 vs. 34%; p < 0.001) and after endurance walking compared with endurance cycling (75 vs. 29%; p < 0.001). In addition, there was no significant change in mean pre- and postwalking twitch quadriceps tensions. However, cycling produced a significant reduction (unpotentiated 7.42 +/- 2.22 vs. 6.48 +/- 2.09 kg [p < 0.001]; potentiated 10.19 +/- 3.99 vs. 8.45 +/- 3.18 kg [p < 0.001]). Pre- to postexercise changes were significantly greater during cycling compared with walking (unpotentiated p = 0.01; potentiated p = 0.003). Leg effort is an infrequent symptom after walking in COPD, and low frequency fatigue of the quadriceps is an infrequent feature of incremental walking.

Aged↗
PubMed2003

Diaphragmatic function in infants with surgically corrected anomalies.

Infants with surgically correctable anomalies, abdominal wall defects (AWD) or congenital diaphragmatic hernia (CDH) may have poor postnatal diaphragmatic function, because the low intra-abdominal pressure experienced by such patients in utero could result in impaired diaphragmatic development. Our objective was to compare postoperative diaphragmatic function of infants with CDH or AWD to that of gestational age-matched controls. Diaphragmatic function was assessed by measurement of the transdiaphragmatic pressure and maximum inspiratory pressure at the mouth generated during crying against an occlusion. In addition, the transdiaphragmatic pressure produced by unilateral and/or bilateral magnetic stimulation of the phrenic nerves (TwPdi) was examined. Lung volume was assessed by measurement of functional residual capacity (FRC) using a helium gas dilution technique. Ten infants with CDH, 26 with AWD infants (19 gastroschisis, seven exomphalos), and 36 gestational age-matched controls were studied. Compared with their matched controls, the eight CDH infants with left-sided defects had significantly lower left (p < 0.01) and right (p < 0.05) TwPdi and FRC (p < 0.01), and the gastroschisis infants, but not those with exomphalos, had significantly lower left and right TwPdi (p < 0.05). There were no significant differences in transdiaphragmatic pressure and maximum inspiratory pressure at the mouth between the CDH or AWD infants and the controls. Diaphragmatic function postoperatively is impaired in infants with CDH or gastroschisis.

Abdominal Wall↗