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Biomedical subjects

C L Marcus

Publications and source records attributed to C L Marcus.

At least 19 recordsLinked to original sources
PubMed2001

Respiratory flutter syndrome: an underrecognized cause of respiratory failure in neonates.

We report the clinical and respiratory data of three neonates with flutter of the diaphragm and intercostal muscles, presenting soon after birth with respiratory failure. The breathing pattern was dirhythmic with superimposed frequencies, one regular and slow (60/min) representing the underlying respiratory rate, the other fast (> 300/min) and limited to inspiration. Nasal continuous positive airway pressure immediately normalized the breathing pattern in one infant, and improved ventilation in the two others. Pharmacologic therapy with chlorpromazine terminated the respiratory flutter and permitted weaning of ventilatory support within a few hours. Coexistent dysphagia suggested a disorder of brainstem function, although the children were otherwise developmentally normal at 8, 10, and 26 mo old. Laryngomalacia and gastroesophageal reflux were also present. We propose that the occurrence of respiratory flutter, dysphagia, laryngomalacia, and gastroesophageal reflux in a neonate constitutes a distinct clinical entity, termed the "respiratory flutter syndrome." The diagnosis of three infants with this presentation during an 18-mo period suggests that this may be a more frequent cause of respiratory failure in newborns than previously recognized.

Diaphragm↗
PubMed2001

Skeletal dysplasias and their effect on the respiratory system.

Children with skeletal dysplasia frequently have pulmonary disease which can be life threatening. These pulmonary problems are due to multiple aetiologies including thoracic and craniofacial anomalies predisposing to restrictive lung disease, upper airway obstruction and central apnoea. Recognition of pulmonary disease and early intervention improves the survival and quality of life for these children.

Bone Diseases, Developmental↗
PubMed2000

Obstructive sleep apnea syndrome: differences between children and adults.

The obstructive sleep apnea syndrome is a common cause of morbidity in childhood. The clinical presentation, pathophysiology, polysomnographic characteristics and treatment differ between children and adults. Measurements of the upper airway pressure-flow characteristics can be useful in evaluating upper airway function in patients with OSAS as well as the normal population.

Adenoids↗
PubMed2000

Late-onset central hypoventilation with hypothalamic dysfunction: a distinct clinical syndrome.

Idiopathic central hypoventilation has occasionally been reported in previously well children after infancy. The relationship between this late-onset central hypoventilation syndrome (LO-CHS) and congenital central hypoventilation syndrome (CCHS) has not been established. Both CCHS and LO-CHS have been associated with neural crest tumors, such as ganglioneuroblastoma and ganglioneuroma, and they generally occur in the presence of a histologically normal central nervous system. At least 10 case reports of idiopathic LO-CHS featured evidence of hypothalamic dysfunction (HD), including hyperphagia, hypersomnolence, thermal dysregulation, emotional lability, and endocrinopathies. We report on a case of LO-CHS/HD successfully treated by nasal intermittent positive pressure ventilation (NIPPV). Despite the commonalties with CCHS, we propose that LO-CHS/HD is a distinct clinical syndrome. In addition to the markedly different age at presentation, features of hypothalamic dysfunction are not seen in CCHS. Review of the literature was undertaken to further clarify the full spectrum of the disease.

Child↗
PubMed2000

Treatment of sleep-disordered breathing in children with myelomeningocele.

The prevalence of moderate to severe sleep-disordered breathing (SDB) in patients with myelomeningocele may be as high as 20%, but little information is available regarding treatment of these patients. To assess the efficacy and complications of treatments for these children, we collected data on 73 patients from seven pediatric sleep laboratories. Obstructive sleep apnea (OSA, n = 30) and central apnea (n = 25) occurred more frequently than central hypoventilation (n = 12). We also describe a sleep-exacerbated restrictive lung disease type of SDB in 6 patients who had hypoxemia during sleep without apnea or central hypoventilation. For each type of SDB, effective treatments were identified in a stepwise process, moving towards more complex and invasive therapies. For OSA, adenotonsillectomy was often ineffective (10/14), whereas nasal continuous positive airway pressure (CPAP) was usually successful (18/21). For central apnea, methylxanthines and/or supplemental oxygen proved sufficient in 2 of 9 and 3 of 6, respectively, but noninvasive positive pressure ventilation was required in 7 children. For central hypoventilation, supplemental oxygen (alone or with methylxanthines), noninvasive positive pressure ventilation, and tracheostomy with positive pressure ventilation were effective in 3, 2, and 2 patients, respectively. Sleep-exacerbated restrictive lung disease always required supplemental oxygen treatment, but in 2 cases also required noninvasive positive pressure ventilation; nutritional and orthopedic procedures also were helpful. Posterior fossa decompression was used for the first three types of SDB, but data were insufficient to delineate specific recommendations for or against its use. In summary, evaluation by an experienced, multidisciplinary team can establish an effective treatment regime for a child with myelomeningocele and SDB.

Adolescent↗
PubMed2000

Pathophysiology of childhood obstructive sleep apnea: current concepts.

The obstructive sleep apnea syndrome (OSAS) is a common and serious condition during childhood. Its pathophysiology remains poorly understood. Although OSAS is related to adenotonsillar hypertrophy in children, adenotonsillar hypertrophy is not likely the sole cause of sleep-disordered breathing in this age group. Rather, large tonsils and adenoids appear to precipitate OSAS in children with underlying abnormalities of upper airway function. Normal children have a relatively narrow upper airway, but maintain airway patency during sleep because of increased upper airway neuromotor tone and an increased central ventilatory drive. We speculate that OSAS occurs in those children lacking the compensatory upper airway neuromotor responses.

Adult↗
PubMed2000

Sleep-disordered breathing in children.

Sleep-disordered breathing, particularly the obstructive sleep apnea syndrome, is common during childhood. Complications include neurocognitive deficits, growth failure, and pulmonary hypertension. Nevertheless, sleep-disordered breathing is often unrecognized in children. New syndromes, such as the upper airway resistance syndrome, have recently been described. Polysomnography is invaluable for the evaluation of sleep-disordered breathing. Advances in diagnosis and management can alleviate much of the morbidity previously associated with sleep-related respiratory disorders.

Child↗
PubMed2000

Sleep architecture and respiratory disturbances in children with obstructive sleep apnea.

Little is known regarding sleep architecture in children with the obstructive sleep apnea syndrome (OSAS). We hypothesized that sleep architecture was normal, and that apnea increased over the course of the night, in children with OSAS. We analyzed polysomnographic studies from 20 children with OSAS and 10 control subjects. Sleep architecture was similar between the groups. Of obstructive apneas 55% occurred during rapid eye movement (REM) sleep. The apnea index, apnea duration, and degree of desaturation were greater during REM than non-REM sleep. OSAS data from the first and third periods of the night (periods A and C) were compared. Both the overall and the REM apnea index increased between periods A and C (11 to 25/h, p < 0.02; and 24 to 51/h, p < 0.01, respectively). There was no difference in Sa(O(2)) over time. Spontaneous arousals, but not respiratory-related arousals, were more frequent during non-REM than REM sleep; these did not change from periods A to C. We conclude that children with OSAS have normal sleep stage distribution. OSAS is predominantly a REM phenomenon in children. Obstructive apnea worsens over the course of the night, independent of the changing amounts of REM sleep. We speculate that this increase in apnea severity may be secondary to upper airway muscle fatigue, changes in upper airway neuromotor control, or changes in REM density.

Apnea↗
PubMed1999

Significance of isolated bradycardia detected by home monitoring.

OBJECTIVE: To determine the cause of isolated bradycardia during home cardiorespiratory monitoring. SETTING: A tertiary care hospital. STUDY DESIGN: A retrospective review of the charts of 8 patients with severe isolated bradycardia on their home monitoring reports. All subjects underwent polysomnography including a pH probe. RESULTS: Monitor reports showed a characteristic pattern of long (30 to 60 seconds) periods of bradycardia, sometimes with asystole, associated with irregular respiratory efforts. All patients had severe gastroesophageal reflux, with a pH <4 for 63% +/- 22% (mean +/- SD) of recording time. No patient had other abnormalities to explain the bradycardia. Bradycardia resolved after successful treatment of reflux. CONCLUSION: A pattern of isolated bradycardia associated with irregular respiratory efforts on home monitoring is highly suggestive of gastroesophageal reflux and should prompt further evaluation and treatment.

Apnea↗
PubMed1999

Developmental changes in response to subatmospheric pressure loading of the upper airway.

Children snore less than adults and have fewer obstructive apneas, suggesting a less collapsible upper airway. We therefore hypothesized that the compensatory upper airway responses to subatmospheric pressure loading decrease with age because of changes in upper airway structure and ventilatory drive. We measured upper airway upstream pressure-flow relationships during sleep in 20 nonsnoring, nonobese children and adults. Measurements were made by correlating maximal inspiratory airflow with the level of nasal pressure applied via a mask. The slope of the upstream pressure-flow curve (S(PF)) was used to characterize upper airway function. We found that S(PF) was flatter in children than in adults (8 +/- 5 vs. 30 +/- 18 ml x s(-1). cmH(2)O(-1), P < 0.002) and that S(PF) correlated with age (r = 0.62, P < 0.01) and body mass index (r = 0. 63, P < 0.01). The occlusion pressure in 100 ms during sleep was measured in six children and two adults; it correlated inversely with S(PF) (r = -0.80, P < 0.02). We conclude that the upper airway compensatory responses to subatmospheric pressure loading decrease with age. This is associated with increased body mass index, even in nonsnoring, nonobese subjects. Ventilatory drive during sleep plays a role in modulating upper airway responses.

Adolescent↗
PubMed1999

Response to inspiratory resistive loading during sleep in normal children and children with obstructive apnea.

The response to inspiratory resistance loading (IRL) of the upper airway during sleep in children is not known. We, therefore, evaluated the arousal responses to IRL during sleep in children with the obstructive sleep apnea syndrome (OSAS) compared with controls. Children with OSAS aroused at a higher load than did controls (23 +/- 8 vs. 15 +/- 7 cmH(2)O. l(-1). s; P < 0.05). Patients with OSAS had higher arousal thresholds during rapid eye movement (REM) vs. non-REM sleep (P < 0.001), whereas normal subjects had lower arousal thresholds during REM (P < 0.005). Ventilatory responses to IRL were evaluated in the controls. There was a marked decrease in tidal volume both immediately (56 +/- 17% of baseline at an IRL of 15 cmH(2)O. l(-1). min; P < 0.001) and after 3 min of IRL (67 +/- 23%, P < 0.005). The duty cycle increased. We conclude that children with OSAS have impaired arousal responses to IRL. Despite compensatory changes in respiratory timing, normal children have a decrease in minute ventilation in response to IRL during sleep. However, arousal occurs before gas-exchange abnormalities.

Airway Resistance↗
PubMed1998

Natural history of primary snoring in children.

It is not known whether children with primary snoring (PS) progress to develop obstructive sleep apnea syndrome (OSAS). Therefore, we repeated polysomnography in a cohort of 20 children diagnosed 1-3 years previously with PS. All children initially presented with symptoms suggestive of OSAS. They were diagnosed with PS when initial polysomnography demonstrated snoring, with less than one obstructive apnea per hour, normal gas exchange, and infrequent arousals. Of 75 potential candidates, 20 were available for reevaluation (33 could not be contacted, 8 had undergone tonsillectomy and adenoidectomy, and 14 declined). Mean age was 6 +/- 4 (SD) years at the time of the initial study. The initial apnea index was 0.2 +/- 0.3, SpO2 nadir 95 +/- 2%, and peak end-tidal PCO2 was 47 +/- 3 mm Hg. At follow-up, all children were reported by their parents to still be snoring; in 20% snoring had reportedly increased, and in 70% there was no change. Eighty percent were thought to have difficulty breathing during sleep. For the group as a whole, there were no significant changes in apnea index, SpO2, or peak end-tidal PCO2. However, two children had mild OSAS on repeat polysomnography (apnea index of 3). We conclude that, in most children, primary snoring does not progress to OSAS over the course of several years. This study indicates that OSAS in the few individuals who do progress is mild. Parental concern about children's breathing patterns during sleep is a poor predictor of polysomnographic abnormalities. However, because many patients were lost to follow-up in this study, further prospective studies are needed.

Adolescent↗
PubMed1998

Sleep-disordered breathing in children with achondroplasia.

OBJECTIVE: Our objective was to characterize sleep-disordered breathing in 88 children with achondroplasia aged 1 month to 12.6 years. RESULTS: At the time of their initial polysomnography, five children had previously undergone tracheostomy, and seven children required supplemental oxygen. Initial polysomnography demonstrated a median obstructive apnea index of 0 (range, 0 to 19.2 apneas/hr). The median number of central apneas with desaturation per study was 0.5 (0 to 49), the median oxygen saturation nadir was 91% (50% to 99%), and the median peak end-tidal pCO2 was 47 mm Hg (36 to 87 mm Hg). Forty-two children (47.7%) had abnormal initial study results, usually caused by hypoxemia. Two children with severe obstructive sleep apnea eventually required continuous positive airway pressure therapy, and three additional children required tracheostomies. CONCLUSIONS: (1) Children with achondroplasia often have sleep-related respiratory disturbances, primarily hypoxemia. (2) The majority do not have significant obstructive or central apnea; however, a substantial minority are severely affected. (3) Tonsillectomy and adenoidectomy decreases the degree of upper airway obstruction in most but not all children with achondroplasia and obstructive sleep apnea. (4) Restrictive lung disease can present at a young age in children with achondroplasia.

Achondroplasia↗
PubMed1998

Arousal and ventilatory responses during sleep in children with obstructive sleep apnea.

Abnormal central regulation of upper airway muscles may contribute to the pathophysiology of the childhood obstructive sleep apnea syndrome (OSAS). We hypothesized that this was secondary to global abnormalities of ventilatory control during sleep. We therefore compared the response to chemical stimuli during sleep between prepubertal children with OSAS and controls. Patients with OSAS aroused at a higher PCO2 (58 +/- 2 vs. 60 +/- 5 Torr, P < 0.05); those with the highest apnea index had the highest arousal threshold (r = 0.52, P < 0.05). The hypercapnic arousal threshold decreased after treatment. For all subjects, hypoxia was a poor stimulus to arousal, whereas hypercapnia and, particularly, hypoxic hypercapnia were potent stimuli to arousal. Hypercapnia resulted in decreased airway obstruction in OSAS. Ventilatory responses were similar between patients with OSAS and controls; however, the sample size was small. We conclude that children with OSAS have slightly blunted arousal responses to hypercapnia. However, the overall ventilatory and arousal responses are normal in children with OSAS, indicating that a global deficit in respiratory drive is not a major factor in the etiology of childhood OSAS. Nevertheless, subtle abnormalities in ventilatory control may exist.

Arousal↗