Gillian M. Nixon

Early airway infection, inflammation, and lung function in cystic fibrosis

Aims: To determine the relation between lower airway infection and inflammation, respiratory symptoms, and lung function in infants and young children with cystic fibrosis (CF). Methods: A prospective study of children with CF aged younger than 3 years, diagnosed by a newborn screening programme. All were clinically stable and had testing as outpatients. Subjects underwent bronchial lavage (BL) and lung function testing by the raised volume rapid thoracoabdominal compression technique under general anaesthesia. BL fluid was cultured and analysed for neutrophil count, interleukin 8, and neutrophil elastase. Lung function was assessed by forced expiratory volume in 0.5, 0.75, and 1 second. Results: Thirty six children with CF were tested on 54 occasions. Lower airway infection shown by BL was associated with a 10% reduction in FEV0.5 compared with subjects without infection. No relation was identified between airway inflammation and lung function. Daily moist cough within the week before testing was reported on 20/54 occasions, but in only seven (35%) was infection detected. Independent of either infection status or airway inflammation, those with daily cough had lower lung function than those without respiratory symptoms at the time of BL (mean adjusted FEV0.5 195 ml and 236 ml respectively). Conclusions: In young children with CF, both respiratory symptoms and airway infection have independent, additive effects on lung function, unrelated to airway inflammation. Further studies are needed to understand the mechanisms of airway obstruction in these young patients.

Urgent Adenotonsillectomy: An Analysis of Risk Factors Associated with Postoperative Respiratory Morbidity

Background The aim of this study was to determine the frequency and type of respiratory complications after urgent adenotonsillectomy (study group) for comparison with a control group of children undergoing a sleep study and adenotonsillectomy for obstructive sleep apnea syndrome. A second aim was to assess risk factors predictive of respiratory complications after urgent adenotonsillectomy. Methods The perioperative course of children who underwent adenotonsillectomy between January 1, 1999, and March 31, 2001, was reviewed. Two groups of children were identified from two different databases: the hospital database for surgical procedures (the study group) and the sleep laboratory database (the control group). The retrospective chart review focused on the preoperative status (including an evaluation for obstructive sleep apnea), anesthetic management, and need for postoperative respiratory interventions. Results A total of 64 consecutive cases for urgent adenotonsillectomy were identified, and 54 children met the inclusion criteria. Thirty-three children (60%) had postoperative respiratory complications necessitating a medical intervention; 11 (20.3%) required a major intervention (reintubation, ventilation, and/or administration of racemic epinephrine or Ventolin), and 22 (40.7%) required a minor intervention (oxygen administration). Six children (11.1%) required reintubation in the recovery room for respiratory compromise. Risk factors for respiratory complications were an associated medical condition (odds ratio, 8.15; 95% confidence interval, 1.81–36.73) and a preoperative saturation nadir less than 80% (odds ratio, 5.54; 95% confidence interval, 1.15–26.72). Sixteen (49%) of the medical interventions were required within the first postoperative hour. Atropine administration, at induction, decreased the risk of postoperative respiratory complications (odds ratio, 0.18; 95% confidence interval, 0.11–1.050. Control group: Of 75 children who underwent a sleep study and adenotonsillectomy, 44 had sleep apnea and were admitted to hospital after elective adenotonsillectomy. Sixteen (36.4%) children had postoperative respiratory complications necessitating a medical intervention. Six percent of the children (n = 3) required a major medical intervention. No child required reintubation for respiratory compromise. Conclusions Severe obstructive sleep apnea syndrome and an associated medical condition are risk factors for postadenotonsillectomy respiratory complications. Risk reductions strategies should focus on their assessment.

Falling asleep: the determinants of sleep latency.

Background: Difficulty falling asleep (prolonged sleep latency) is a frequently reported problem in school-aged children. Aims: This study aimed to describe the distribution of sleep latency and factors that influence its duration. Methods: 871 children of European mothers were recruited at birth. 591 (67.9%) children took part in the follow-up at 7 years of age. Sleep and daytime activity were measured objectively by an actigraph worn for 24 h. Results: Complete sleep data were available for 519 children (87.8%) with a mean age of 7.3 years (SD 0.2). Median sleep latency was 26 minutes (interquartile range 13–42). Higher mean daytime activity counts were associated with a decrease in sleep latency (−1.2 minutes per 102 movement count per minute, p = 0.05). Time spent in sedentary activity was associated with an increase in sleep latency (3.1 minutes per hour of sedentary activity, p = 0.01). Conclusions: These findings emphasise the importance of physical activity for children, not only for fitness, cardiovascular health and weight control, but also for promoting good sleep.

Pleural fluid nucleic acid testing enhances pneumococcal surveillance in children

Background and objective:  National surveillance of invasive pneumococcal disease (IPD) includes serotyping Streptococcus pneumoniae (SP) isolates from sterile site cultures. PCR is more sensitive and can identify more SP serotypes (STs) in culture‐negative samples. The aim of this study was to determine whether enhanced surveillance of childhood empyema, using PCR, provides additional serotype information compared with conventional surveillance.

Can actigraphy measure sleep fragmentation in children

Objective The gold standard assessment for sleep quality is polysomnography (PSG). However, actigraphy has gained popularity as an ambulatory monitor. We aimed to assess the value of actigraphy in measuring sleep fragmentation in children. Methods 130 children aged 2–18 years referred for assessment for sleep disordered breathing (SDB) were recruited. The arousal index (AI) scored from PSG was compared to the actigraphic fragmentation index (FI) and number of wake bouts/h. Results The ability of actigraphic measures to correctly classify a child as having an AI>10 events/h rated as fair for the FI and poor for wake bouts/h (area under the receiver operator characteristic curve, 0.73 and 0.67, respectively). Conclusion Actigraphy provides only a fair indication of the level of arousal from sleep in children. While the limitations of actigraphy prevent it from being a diagnostic tool for SDB, it still has a role in evaluating sleep/wake schedules in children.

Sleep studies frequently lead to changes in respiratory support in children.

Aim:  International guidelines recommend that children who are managed at home with mechanical respiratory support (RS) should have sleep studies performed every 6–12 months. This recommendation is based on expert opinion, with little evidence to support it. No studies have been undertaken to examine the utility of sleep studies in children on RS.

A bedside assay to detect streptococcus pneumoniae in children with empyema

Empyema is a complication of pneumonia, commonly caused by Streptococcus pneumoniae.

The role of physiological studies and apnoea monitoring in infants

There is evidence that failure of cardio-respiratory control mechanisms plays a role in the final event of the Sudden Infant Death Syndrome (SIDS). Physiological studies during sleep in both healthy term born infants and those at increased risk for SIDS have been widely used to investigate how the major risk and protective factors for SIDS identified from epidemiological studies might alter infant physiology. Clinical polysomnography (PSG) in infants who eventually succumbed to SIDS however demonstrated abnormalities that were neither sufficiently distinctive nor predictive to support routine use of PSG for infants at risk for SIDS. PSG findings have also been shown to be not predictive of recurrence of Apparent Life Threatening Events (ALTE) and thus international guidelines state that PSG is not indicated for routine evaluation in infants with an uncomplicated ALTE, although PSG may be indicated when there is clinical evidence of a sleep related breathing disorder. A decision to undertake home apnoea monitoring should consider the potential advantages and disadvantages of monitoring for that individual, in the knowledge that there is no evidence of the efficacy of such devices in preventing SIDS.

Differential effects of sleep disordered breathing on polysomnographic characteristics in preschool and school aged children.

OBJECTIVE Childhood sleep disordered breathing (SDB) peaks in the preschool years. We aimed to compare the effects of SDB on polysomnographic characteristics between preschool and school aged children. PARTICIPANTS AND METHODS One hundred and fifty-two preschool (3-5 y) and 105 school-aged (7-12 y) children, referred for assessment of SDB, plus controls (39, 3-5 y and 34, 7-12 y) with no history of snoring underwent overnight polysomnography. Subjects were grouped by their obstructive apnea hypopnea index (AHI) into those with primary snoring, mild obstructive sleep apnea (OSA), and moderate/severe OSA. The effects of SDB severity on sleep architecture and respiratory characteristics were compared between the age cohorts using quantile regression. RESULTS There was an average reduction in median sleep efficiency of 3.5% (p=0.004) and an average increase in median WASO of 2% (p=0.08) between the age cohorts across the severity groups, with sleep efficiency falling and WASO increasing with increasing SDB severity in the school-aged, but not the preschool, cohort. There was an average difference in median central AHI of 0.6 events/h (p<0.001) between the age cohorts across the severity groups, with the 3-5 y old cohort but not the 7-12 y old cohort having more central apneas with increasing SDB severity. CONCLUSIONS We have demonstrated clinically important, age-related differences in sleep architecture in children with SDB. Preschool children with SDB maintain sleep efficiency and awaken fewer times throughout the night than do school aged children with a comparable severity of SDB, but experience more central apneas. This may have implications for the outcomes and treatment of SDB in children of different ages.

ASTA/ASA addendum to the AASM guidelines for the recording and scoring of paediatric sleep

Pl01 The effect of myocardial infarction on sleep in mice C. O’ DONNELL University of Pittsburgh, Pittsburgh, PA, USA There is growing awareness that myocardial infarction (MI) and sleep are mechanistically connected and that both shortened sleep duration and increased daytime sleepiness increase risk for cardiovascular morbidity and mortality. However, investigations between cardiac events and sleep are confounded by the high prevalence of obesity and sleep apnea that have obscured our ability to determine more direct mechanistic relationships between MI and sleep. Consequently, we have no direct evidence if a cause and effect relationship exists between heart failure and altered sleep architecture. We have developed a murine model of experimentally-induced MI (ligation of the left descending coronary artery: CAL) to study the impact on sleep. We conducted initial studies in 18 mice subjected to CAL surgery and six mice subjected to sham surgery (loose tie around coronary artery) to examine changes in sleep architecture that occurred within the first 8 days after experimental MI. In control mice after sham surgery there was a small and transient increase in NREM sleep during the dark/ active period for post-operative days 1–3, likely reflecting recovery from anesthesia and surgery. In contrast, CAL mice showed a marked increase in NREM sleep (due to an increased number of NREM sleep bouts), but no change in REM sleep, during the dark/active period. The effect was sustained through to 8 days, with NREM sleep in the dark/active period remaining 47% higher (P < 0.05) in the CAL group versus sham group. The marked increase in total time of NREM sleep in the dark/active period for CAL mice was accompanied by a reduction in the time to fall asleep following arousal/awakening and an augmented sleep pressure, as determined by an increase over time in the spectral delta power. CAL was also associated with a greater overall number of arousals compared to sham mice in both the light and dark periods. Taken together, the above data indicate that in the absence of co-morbidity MI can disrupt sleep in two significant ways – first, by increasing daytime sleepiness when the animal should be predominantly awake, which we propose occurs through activation of pro-inflammatory pathways; second, by severely fragmenting sleep whenever sleep does occur, which we propose occurs through activation of sympathetic pathways.