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Biomedical subjects

C E Sullivan

Publications and source records attributed to C E Sullivan.

At least 37 records · Page 2Linked to original sources
PubMed1999

Obstructive sleep apnea in infants and its management with nasal continuous positive airway pressure.

STUDY OBJECTIVES: Nasal continuous positive airway pressure (nCPAP) is the most common treatment for obstructive sleep apnea (OSA) in adults, and it has been effective in the treatment of OSA in children. We wanted to determine the effectiveness of long-term nCPAP therapy for OSA in infants. PATIENTS: Twenty-four infants who had OSA were treated with nCPAP via nose mask. These infants had clinical histories that included a family history of sudden infant death syndrome, an apparent life-threatening event, or facial and upper airway anatomic abnormalities. INTERVENTIONS: Overnight polysomnographic studies were performed to assess the severity of OSA in each infant and to determine the appropriate level of continuous positive airway pressure (CPAP). Studies were repeated to determine the progress of OSA and the continuing need for CPAP in each infant. RESULTS: nCPAP pressures between 4 and 6 cm H2O prevented obstruction and reversed sleep disturbances that were associated with OSA. Eighteen of the infants continued treatment at home from 1 month to > 4 years. CPAP therapy was discontinued in 13 infants after their OSA resolved. Five infants who have upper airway anatomic abnormalities remain on CPAP, and the pressure level required to prevent obstructive events during sleep has needed to be increased to as high as 10 cm H2O. CONCLUSIONS: nCPAP is an effective therapy for the management of OSA in infants, and it can be used effectively in the home environment. Regular follow-up is necessary, because the requirements for CPAP and pressure levels change with the infant's growth and development.

Female↗
PubMed1998

Evolution of sleep-disordered breathing and sleep in infants.

OBJECTIVE: The evolution of sleep-disordered breathing and sleeping patterns in a group of high-risk infants was studied throughout the first year of life. METHODOLOGY: Eleven infants with documented sleep apnoea underwent overnight polysomnographic studies at monthly intervals to 6 months, then at 9 and 12 months of age. RESULTS: All infants had central apnoea and obstructive events recorded on their initial sleep studies. The sleep-disordered breathing in these infants was associated with disturbed sleeping patterns. The amount of rapid eye movement (REM) sleep recorded in each study was inversely proportional to the amount of apnoea. The amount of apnoea and sleep disturbances were highest at 2 months of age and then progressively improved and obstructive events resolved by 1 year of age. CONCLUSIONS: The respiratory abnormalities and sleep disturbances peaked in severity at the age reported to have the highest incidence of sudden infant death syndrome (SIDS) and may have implications for its aetiology.

Humans↗
PubMed1998

End-expiratory lung volume during arm and leg exercise in normal subjects and patients with cystic fibrosis.

There are no reports concerning the regulation of end-expiratory lung volume (EELV) and flow-volume relationships during upper limb exercise in health and disease. We studied EELV during such exercise in 22 adults with cystic fibrosis (CF) and nine age-matched healthy control subjects. Subjects with CF were grouped according to the severity of their lung disease, as follows: mild = FEV1 > 80% predicted; moderate = FEV1 40 to 80% predicted, and severe = FEV1 < 40% predicted. EELV was calculated from measurements of inspiratory capacity (IC) made at each workload during an incremental arm and leg ergometer test to peak work capacity. In the control group, the decrease in EELV was significantly smaller for arm than for leg exercise at peak work (-0.13 L versus -0.53 L, p < 0.001) and for arm than for leg exercise at an equivalent submaximal ventilation (-0.13 L versus -0.46 L, p < 0.01). In the groups with moderate and severe CF, arm exercise resulted in an increase in EELV from resting levels (dynamic hyperinflation) that was not significantly different from the increase observed for leg exercise. For CF subjects there was a significant inverse relationship between FEV1 and changes in EELV from rest to peak arm exercise (r = -0.46, p < 0.05). In normal subjects, there was a difference in the EELV response for arm versus leg exercise. In CF subjects with airflow limitation, dynamic hyperinflation occurred with both forms of exercise.

Adolescent↗
PubMed1998

Ventilatory control in patients with sleep apnoea and left ventricular dysfunction: comparison of obstructive and central sleep apnoea.

Sleep apnoea is common in patients with heart failure. While most patients have central sleep apnoea (CSA), a minority have obstructive sleep apnoea (OSA). The pathophysiology of CSA is not well understood. We hypothesized that central chemosensitivity would be an important pathophysiological factor in patients with CSA, and not in OSA. The aim of this study was to compare ventilatory responses between patients with CSA and those with OSA. Acute ventilatory responses to eucapnic hypoxia and hyperoxic hypercapnia were measured during wakefulness in 34 patients (33 males and one female, aged 59+/-8 yrs (mean+/-SD)), with stable medically-treated left ventricular dysfunction (LVD) and sleep apnoea (18 OSA and 16 CSA). Patients with CSA had a decreased awake end-tidal carbon dioxide tension (4.1+/-0.5 kPa), increased ventilatory response to carbon dioxide (0.65+/-0.43 L.min.(-1).kPa PCO2(-1)), and eucapnic hypoxic responses in the normal range (0.6+/-0.4 L.min(-1)/% fall in arterial oxygen saturation (Sa,O2)). In contrast, patients with OSA had normal end-tidal carbon dioxide tension (4.9+/-0.5 kPa), and normal ventilatory responses to hypercapnia (0.29+/-0.16 L.min(-1).kPa PCO2(-1)) and hypoxia (0.5+/-0.5 L-min(-1)/% fall in Sa,O2). These findings suggest that augmented chemosensitivity to hypercapnia may be an important factor in the pathophysiology of central sleep apnoea in patients with heart failure.

Adult↗
PubMed1998

Time course of pulmonary artery pressure during sleep in sleep apnoea syndrome: role of recurrent apnoeas.

Recent results in animals have suggested that repetition of hypoxaemic stimuli may result in a progressive increase in pulmonary arterial pressure (Ppa). The purpose of the present study was to investigate the effects of recurrent obstructive apnoeas on Ppa. We have, therefore, examined the nocturnal trend of Ppa in seven obstructive sleep apnoea syndrome (OSAS) patients and in five snorers. Mean Ppa was measured before, at the start, at the end and after the selected apnoeas. The analysis was performed for each 1 h period for at least 7 h throughout the night on at least 10 randomly selected apnoeas per hour. In snorers, 100 randomly chosen values were measured during every hour of the night. In the morning after the nocturnal study, the Ppa responses to acute hypoxia and hypercapnia were measured. No Ppa changes throughout the 7 h were found during sleep in snorers [Ppa slope:-0.002+/-0.10 mmHg x h(-1)]. In OSAS patients a small but significant increase in Ppa throughout the night was noted, affecting the values before [Ppa slope: 0.7+/-0.16 mmHg x h(-1)], at the start of apnoea [Ppa slope: 0.530.1 mmHg x h(-1)] as well as at the end [Ppa slope: 0.44+/-0.08 mmHg x h(-1)] and in the postapnoeic period [Ppa slope: 0.55+/-0.1 mmHg x h(-1)]. When we limited the analysis to nonrapid eye movement (NREM) sleep, a trend in progressive Ppa was also present, irrespective of changes in apnoea duration and apnoea desaturation. The Ppa rise during the night was not affected by diurnal Ppa pulmonary vascular response to hypoxia and hypercapnia or indices of sleep apnoea severity. We conclude that in obstructive sleep apnoea, pulmonary artery pressure progressively increases during the night, reflecting the cumulative effects of apnoeas and nocturnal hypoxaemia.

Adult↗
PubMed1998

The effect of octreotide on breathing and the ventilatory response to CO2 in conscious dogs.

It has been reported that injection of somatostatin into the brain-stem will lead to apnoea in animals. The aim of this study was to determine whether peripheral administration of octreotide, an analogue of somatostatin, could influence the control of breathing. We measured the tidal volume, respiratory rate and ventilatory response to CO2, before and after the intravenous injection of two dose levels of octreotide (0.1 mg and 0.5 mg) or saline in four conscious adult dogs. Injection of octreotide altered the breathing pattern with a mean decrease in the respiratory frequency of 23% (p<0.05) and an increase in the tidal volume by 16% (p<0.05), resulting in no net change in ventilation. The normal value of the ventilatory response to CO2 ranged between 1.0-3.2 L x min(-1) x mmHg(-1), with a minor variance within each dog but a significant difference amongst the four dogs (p<0.05). No significant change in the ventilatory response to CO2 was observed after octreotide. We conclude that intravenous octreotide alters the pattern of breathing but preserves minute ventilation; peripheral administration of octreotide does not influence the ventilatory response to CO2.

Animals↗
PubMed1997

Nasal mask continuous positive airway pressure in the treatment of chronic nocturnal cough in a young child.

The objective of this case report was to define the effects of nasal mask continuous positive airway pressure (CPAP) on the respiratory and sleep characteristics of a 3 year-old boy with a 2 year history of snoring and 1 year history of chronic nocturnal cough. The method employed was all-night polysomnography before and during treatment with CPAP after the identification of partial upper airway obstruction in association with cough. The results indicated that the child had evidence of mild upper airways obstruction on initial all-night sleep study. Nasal mask CPAP was instituted. On a subsequent sleep study 4 weeks later, this was documented to prevent the upper airway obstruction at a pressure of 5.2 cm of water. In addition, nasal mask CPAP markedly reduced the nocturnal coughing, the total number of coughs decreasing from 92 to one. The rate of cough per h of study (cough disturbance index) decreased from 9.8-0.1. Sleep efficiency (total sleep time as a percentage of study duration) improved on CPAP from 87 to 99%. This study suggests that chronic nocturnal cough can result from upper airway obstruction in sleep in children and is an important initial observation.

Child, Preschool↗
PubMed1997

Pulmonary artery pressure response to hypoxia in sleep apnea.

The pulmonary artery pressure (Ppa) responses to short runs of acute hypoxia at two different levels of end-tidal CO2 were measured in nine normal subjects and in 20 patients with moderate to severe obstructive sleep apnea (OSA). In normal subjects the mean increase in Ppa in response to eucapnic hypoxia was 8 +/- 2 mm Hg (SEM) and was not different from the response to hypercapnic hypoxia (9 +/- 2 mm Hg, p > 0.2). In patients with OSA, the mean increase of Ppa was 8 +/- 1 mm Hg to eucapnic hypoxia, and the response to hypercapnic hypoxia was higher at 10 +/- 1 mm Hg (p = 0.01). Pulmonary pressor response to hypoxia was augmented (> 10 mm Hg) by hypercapnia in four of 20 patients with OSA but in none of the normal subjects. Normoxic hypercapnia alone was a weak stimulus, increasing Ppa by > 5 mm Hg in only two of nine patients with OSA studied. In conclusion, Ppa increases in both normal subjects and patients with OSA exposed to a ramp of acute isocapnic hypoxia. There were clear interindividual differences in pulmonary artery response. Hypercapnia did not produce clinical significant changes in Ppa in either group.

Adult↗
PubMed1997

Aortic root dilatation in Marfan's syndrome: a contribution from obstructive sleep apnea?

We report two cases of Marfan's syndrome with coexistent obstructive sleep apnea (OSA) in which treatment with nasal continuous positive airway pressure was associated with attenuation of aortic root dilatation, a serious complication of the syndrome. We speculate that coexistent OSA promotes progressive aortic dilatation in some patients with Marfan's syndrome.

Adolescent↗
PubMed1996

Respiratory and body movements as indicators of sleep stage and wakefulness in infants and young children.

Conventional polysomnographic (PSG) sleep staging to sleep staging based on a static-charge-sensitive bed (SCSB) recording in infants and young children was compared. The study consisted of whole-night clinical sleep studies in 22 children at 24 weeks (SD 24, range 1-79 weeks) of age. Most of the children presented with respiratory disturbances during sleep. From the SCSB record, sleep stages were differentiated according to regularity of breathing, presence of body movements, and most important, presence of high-frequency components of breathing (SCSB spikes). With both methods, three sleep/wake stages were distinguished: rapid eye movement (REM) sleep, non-rapid eye movement (NREM) sleep and wakefulness. The average interscorer reliability of the PSG sleep staging controlled in nine subjects was 88%. The average concordance between the two methods ranged from 82 to 85%, depending on the criteria used for scoring the SCSB. The mean sensitivity of the SCSB to detect NREM sleep ranged from 77 to 90% and the mean sensitivity to detect REM sleep ranged from 61 to 86%. The mean positive predictive value was 89-96% for NREM sleep and 54-67% for REM sleep. In conclusion, REM sleep is characterized by irregular breathing with superimposed fast respiratory movements. These changes are specific enough to allow distinction between episodes of NREM sleep, REM sleep and wakefulness with the non-invasive SCSB method in infants and young children. Incomplete concordance between PSG and SCSB score was most frequently observed during sleep stage transition periods, where the behavioural state and electrophysiological criteria disagreed. When combined with the PSG, the SCSB provides complementary information about the behavioural state of child.

Electroencephalography↗
PubMed1996

Sleep-disordered breathing and its effects on sleep in infants.

Sleep apnea has been recorded in many infants, but little data exist concerning the amount and range of apnea in infants. We studied 49 infants referred to the sleep disorders unit. Single polysomnographic studies were performed on each infant. We examined the amount of apnea, presence and amount of upper airway obstruction and the sleeping pattern in each infant. Central apnea was common to all infants and varied in amount. Upper airway obstruction, recorded as mixed apnea, was found in 36 infants. Twenty of these infants had only occasional mixed apnea ( < 2 apneas/hour), whereas 16 infants displayed a higher amount of obstruction. All infants were separated into two groups according to amount of apnea and obstruction. Sixteen infants with obstruction plus 3 infants with a high amount of central apnea represented group I. The remaining 30 infants represented group II. Marked differences in the sleeping pattern were found when the groups of infants were separated. Infants from group I had significantly less rapid eye movement (REM) sleep than infants from group II. We conclude that sleep-disordered breathing in infants is associated with disruptions in sleep.

Electrocardiography↗