Biomedical subjects

Olivia Williams

Publications and source records attributed to Olivia Williams.

6 recordsLinked to original sources

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↗

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

Prediction of outcome from the chest radiograph appearance on day 7 of very prematurely born infants.

UNLABELLED: Our aim was to determine whether the chest radiograph appearance at 7 days predicted chronic lung disease development (oxygen dependency at 36 weeks post-menstrual age) or death before discharge and if it was a better predictor than readily available clinical data. Two consecutive studies were performed. In both, chest radiographs taken at 7 days for clinical purposes were assessed using a scoring system for the presence of fibrosis/interstitial shadows, cystic elements and hyperinflation and data were collected regarding gestational age, birth weight, use of antenatal steroids and post-natal surfactant and requirement for ventilation at 7 days. Oxygenation indices were calculated in the first study (study A) at 120 h and in the second (study B) at 168 h. In study A, there were 59 infants with a median gestational age of 26 weeks (range 24 to 28 weeks) and in study B, 40 infants with a median gestational age of 27 weeks (range 25-31 weeks). In both studies, infants who developed chronic lung disease had a significantly higher total chest radiograph score, with a higher score for fibrosis/interstitial shadowing than the rest of the cohort. Infants who died before discharge differed significantly from the rest with regard to significantly higher scores for cysts. In both studies, the areas under the receiver operator characteristic curves with regard to prediction of chronic lung disease were higher for the total chest radiograph score compared to those for readily available clinical data. CONCLUSION: In infants who require a chest radiograph for clinical purposes at 7 days, the chest radiograph appearance can facilitate prediction of outcome of infants born very prematurely.

Chronic Disease↗

PubMed2003

Post-natal corticosteroid use.

UNLABELLED: Corticosteroids given systemically in the first 2 weeks after birth may reduce chronic lung disease (CLD) and mortality, but there are concerns regarding the long-term adverse effects which may have influenced prescribing habits. The aim of this study was to determine whether corticosteroids were still prescribed and, if so, was there a consensus regarding the most appropriate regimen to use. Consultant paediatricians at all 223 neonatal units in the United Kingdom were sent a questionnaire asking which route, timing, dosage and indications they used when administering corticosteroids. There was a 72% response rate to the survey. Of those who responded, 33% never prescribed steroids and 3.75% gave inhaled steroids only. Corticosteroids were not prescribed in the 1st week after birth, 21.1% of respondents commenced administration in the 2nd week and 33.3% only outside the neonatal period. A total of 48% prescribed a daily dose of 0.5 mg/kg per day, 33% gave lower doses, with 7.9% prescribing 0.1 mg/kg per day or less. The majority (77%) prescribed corticosteroids only to ventilator-dependent infants, others also gave corticosteroids to chronically continuous positive airway pressure- or oxygen-dependent infants. CONCLUSION: There are wide variations in corticosteroid usage. This emphasises the need to identify if there is a corticosteroid dosage regimen with a positive risk/benefit ratio.

Administration, Inhalation↗

PubMed2003

Nasal and lower airway levels of nitric oxide in prematurely born infants.

BACKGROUND: Nitric oxide (NO) is produced by various cells in the respiratory tract, but the majority is released from the paranasal sinuses in adults. The paranasal sinuses in infants are only partially pneumatised. Thus, nasal NO would be predicted to be low in infants measured soon after birth and/or born very prematurely; this has implications for the measurement of exhaled NO and interpretation of the results obtained. OBJECTIVES: To determine whether nasal NO could be detected in very immature infants, particularly soon after birth, and whether nasal or lower airway NO levels were influenced by gestational age or postnatal age. PATIENTS: Fifteen infants, with median gestational age of 27 weeks (range 25-32 weeks). METHODS: Nasal and lower airway NO measurements were attempted on days 1, 3, 5, 7, 14, 21, and 28 after birth. Measurements were only made while the infants remained ventilated. Nasal NO was sampled directly from the nasal space and lower airway. NO was sampled from a catheter positioned so that its tip lay at the lower end of the endotracheal tube. RESULTS: Nasal NO was detected in all infants on all study occasions and the levels were greater than those from the lower airway. Nasal and lower airway NO levels did not correlate significantly with gestational age, but lower airway NO levels correlated with postnatal age (r=0.86, p=0.014). CONCLUSION: Even in very immature infants examined in the first day after birth, care must be taken to avoid contamination with nasal NO, if lower airway levels are to be accurately assessed.

Breath Tests↗

PubMed2003

Influence of ventilatory settings and sampling position on measurements of simulated exhaled nitric oxide levels.

Chronic lung disease is a common adverse outcome of prematurely born infants and is associated with an early inflammatory response, which persists over weeks. As a consequence, it is possible that exhaled nitric oxide levels might be raised in affected infants. The majority of such infants will be ventilated in the first weeks of birth and thus it is important to determine the influence of mechanical ventilation on nitric oxide levels. As a consequence, our aim was to determine whether, during mechanical ventilation, simulated exhaled nitric oxide levels were influenced by changes in ventilator settings or the sampling catheter position. A lung model was created consisting of a rubber bag inside a 11 jar. An endotracheal tube (ETT) was fixed securely within the neck of the bag. Nitric oxide was delivered into the bag at a constant rate to simulate production and sampled from within the ETT and the bag. The sampled nitric oxide was analysed using a Sievers chemiluminescence analyser. The ETT was attached to a neonatal ventilator and a nitric oxide scavenger placed in the ventilator's inspiratory limb to ensure nitric oxide free gas was delivered. Comparison of different sampling positions revealed that the highest peak nitric oxide level within the ETT was at the tip. Increasing peak inflating pressure and ventilator rate resulted in a decrease in the peak nitric oxide levels. Increasing the inspired oxygen concentration also was associated with a reduction in the peak nitric oxide levels, the effect being more pronounced when larger volume lung models were examined. The results emphasized that the conditions of measurement must be standardized in infants receiving respiratory support, if exhaled nitric oxide results are to be appropriately interpreted.

Air↗