Lecithin aerosols generated ultrasonically above 25 degrees C.

Dl-Dipalmitoyl-alpha-lecithin, suspended in 0.15-molar sodium chloride solution by sonic cavitation at 20 kilohertz, can be aerosolized by an 800-kilohertz ultrasonic generator only at temperatures above 25 degrees C. The aerosol thus produced is exceptionally stable against evaporation even at particle radii of 0.1 to 0.6 micron; this suggests applicability to the therapy of pulmonary disorders.

Power spectrum analysis of heart rate fluctuation: a quantitative probe of beat-to-beat cardiovascular control.

Power spectrum analysis of heart rate fluctuations provides a quantitative noninvasive means of assessing the functioning of the short-term cardiovascular control systems. We show that sympathetic and parasympathetic nervous activity make frequency-specific contributions to the heart rate power spectrum, and that renin-angiotensin system activity strongly modulates the amplitude of the spectral peak located at 0.04 hertz. Our data therefore provide evidence that the renin-angiotensin system plays a significant role in short-term cardiovascular control in the time scale of seconds to minutes.

Periodic breathing in infants with near-miss sudden infant death syndrome.

Twelve-hour nocturnal home recordings of respiration and heart rates were obtained during sleep in 32 infants with near-miss sudden infant death syndrome (SIDS) and in 32 control infants, and the recordings were analyzed for periodic breathing. An episode of periodic breathing was defined as three or more apneic pauses of three or more seconds. The duration of respirations interrupting the pauses was 20 seconds or less. Analysis revealed a statistically significant difference (P less than .001) between the two groups, using criteria of percent of periodic breathing episodes, number of periodic breathing episodes/100 min of recorded sleep time, average duration of all episodes, and duration of the longest episode of periodic breathing. It is concluded that periodic breathing is present in excessive amounts during sleep in infants with near-miss sudden infant death syndrome.

Preferential distribution of lobar emphysema and atelectasis in bronchopulmonary dysplasia.

The chest roentgenograms of 142 neonates who survived mechanical ventilation for respiratory distress syndrome (N = 99) and prolonged apnea (N = 43) were reviewed. Thirty-seven infants had bronchopulmonary dysplasia (BPD) and 17 of these developed lobar hyperinflation of the right lower lobe and collapse of the right upper lobe. Regional lung function was measured with a xenon 133 technique in three of these infants and in five other patients who either died or were lost to follow-up. All had BPD with right lower lobe overinflation. Ventilation was less in the lower regions than the upper regions bilaterally (P less than .001), indicating that the hyperinflation of the lower lobes was not compensatory for upper lobe collapse but was due to emphysema. Mean regional perfusion was equal in the upper and lower regions of the chest. This preferential distribution of lobaremphysema and ipsilateral atelectasis in BPD tended to present and regress simultaneously, but in many infants it lasted as long as eight weeks. Only one infant with persistent atelectasis developed pneumonia. The best mode of therapy appears to be supportive.

Treatment of apnea and excessive periodic breathing in the full-term infant.

Twenty-two full-term infants, aged 0 to 6 weeks, with a history of unexplained apnea and respiratory abnormalities on pneumogram recordings, were treated with theophylline (average dose 7.5 mg/kg/day and average serum level 11 micrograms/ml). Subsequent recordings showed a significant decrease in the amount of periodic breathing (14.3% vs 0.7%) and apnea 10 to 14.9 seconds (12.8 vs 1.0/100 min) when compared to the initial pneumogram. It is concluded that theophylline therapy in this group of infants will result in a reduction of apnea and periodic breathing.

Episodic complete airway obstruction in infants.

Four infants with episodic silent complete obstructed apnea are described. All had central sleep apnea, three had hypoventilation, and none had obstructive apnea observed on polygraphic recordings. Two infants were siblings of a sudden infant death syndrome victim and one was a sibling of a "near miss" infant. One infant died as a result of a prolonged episode that began while she was awake. In two infants apnea has been controlled with theophylline administration and in the third infant resolution of the episode was temporally related to atropine administration.

The pediatric pneumogram: a new method for detecting and quantitating apnea in infants.

A clinically useful diagnostic method has been developed for detecting and quantitating periods of apnea in pediatric patients. This procedure, called the pediatric pneumogram, permits the continuous recording on magnetic tape, for periods of up to 13 hours, of the respiratory pattern of infants utilizing an impedance technique. This test has been employed successfully in a variety of infants to evaluate respiratory activity and has permitted the objective documentation of apneic and cyanotic episodes, as well as an assessment of the eff ectiveness of therapy.

Familial occurrence of sudden infant death syndrome and apnea of infancy.

We sought to determine the outcome of infants born to families with multiple victims of sudden infant death syndrome (SIDS) and/or apnea of infancy. Seventy-three infants, born to families who had two or more previous siblings who had either died of SIDS or who were monitored at home for apnea of infancy or for abnormal results on polysomnogram and/or pneumogram recording, were prospectively monitored. The infants underwent polysomnogram and pneumogram recordings and were subsequently monitored at home with a cardiorespiratory monitor. All episodes of apnea were immediately reviewed. Thirteen infants (18%) had subsequent severe episodes of apnea and five other infants (7%) died during a subsequent episode. All deaths occurred in families who had two or more SIDS victims. The outcome for the 17 infants who were half siblings was similar to the outcome for full siblings. Clinical data of the infants and results of evaluation were not predictive of outcome.

Long-term follow-up of children with congenital central hypoventilation syndrome.

The long-term clinical course of six patients with congenital central hypoventilation syndrome is described. During the neonatal period, the patients had prolonged apneas and hypoventilation, in the absence of cardiac, pulmonary, or neuromuscular disease. After an initial period of respirator dependency, they became able to sustain normal gas exchange while awake. During sleep, however, profound hypoventilation developed, and tracheostomy and mechanical ventilation were required. Ventilatory responses to hypercapnia and hypoxia were depressed or absent and did not improve with time. One patient was able, at 2 years of age, to breathe spontaneously during sleep with only moderate hypoventilation. The others, now 4 to 14 years of age, still need ventilatory support during sleep. Complications, such as cardiac failure and hypoxic seizures, mostly occurred early in the course and resolved with correction of insufficient mechanical ventilation. Speech acquisition was possible with the use of a special stoma plug. All patients were managed at home, and with appropriate support, the parents were able to provide safe ventilatory care with low morbidity and no mortality.

Pneumogram recordings in infants resuscitated for apnea of infancy.

Infants who sustained a spell of apnea of infancy during which they were resuscitated have been shown to be at increased risk for sudden infant death syndrome. To determine the value of the pneumogram as a predictor of outcome in this population, the first pneumogram obtained of 51 such infants was analyzed. The infants were grouped on the basis of subsequent outcome during a course of monitoring: group 1--infants who died during a subsequent event; group 2--infants who received resuscitation or vigorous stimulation to terminate a subsequent spell; group 3--infants who survived and did not have a significant subsequent episode. The results for these infants were compared with those of a control group matched for age and sex. A detailed, blinded computer analysis revealed no significant difference in the results of the pneumogram analysis between the three groups. It did not identify the infants in whom apneic spells necessitating resuscitation subsequently developed or those who died. However, when compared with the control group, infants with apnea of infancy had significantly higher mean respiratory rates, heart rates, and tachycardia indexes. It is concluded that, although the first pneumogram does not predict the risk of an adverse outcome in a population of infants with severe apnea of infancy, it does reveal subtle cardiorespiratory differences between study and control infants.

Identification of a high-risk group for sudden infant death syndrome among infants who were resuscitated for sleep apnea.

Of the 1,153 infants who completed monitoring by Aug 1, 1984, through our program at Massachusetts General Hospital, 76 infants had an initial apnea spell during sleep which was characterized by a change in tone and color, was unresponsive to repeated vigorous stimulation, and was terminated only after mouth to mouth resuscitation. The infants were hospitalized for observation and evaluation, and no cause could be identified. All were discharged on a home apnea or cardiorespiratory monitor, and subsequent episodes of apnea and/or bradycardia were reviewed. We grouped infants based on the intervention used to terminate subsequent episodes: Group 1, resuscitation; group 2, vigorous stimulation; and group 3, neither resuscitation or vigorous stimulation. There was no significant difference in clinical features or in the results of the initial evaluation in groups 1 and 2, compared with group 3. However, the mortality rate was significantly higher in group 1 (4/13) and group 2 (3/12) than in group 3 (3/51) (P less than .007). Siblings of victims of sudden infant death syndrome (n = 8) were at a significantly higher risk of an adverse outcome (two deaths and four resuscitations) than nonsiblings (P less than .02). A seizure disorder that developed during monitoring was associated with a high mortality (4/11 v 6/65, P less than .02). We conclude that these relatively rare infants who have sleep-onset apnea that responded only to resuscitation and have a subsequent similar episode or are siblings of victims of sudden infant death syndrome or develop a seizure disorder during monitoring have a very high risk of dying (31%, 25%, and 36% respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Periodic breathing in siblings of sudden infant death syndrome victims.

To determine the incidence of periodic breathing (PB) episodes during sleep, 48 subsequent sudden infant death syndrome siblings and 48 control infants, matched by sex, gestational age, and chronologic age, were studied by home pneumogram technique. The sudden infant death syndrome siblings had a statistically significant increase in the percent of sleep time spent in PB, in the number of episodes/100 minutes of PB, in the longest episode PB, and in the average duration of all episodes of PB. We conclude that PB is present in a higher amount in sudden infant death syndrome siblings as compared to control infants.

Parents' perceptions of the psychological and social impact of home monitoring.

Self-assessments of 133 parents' (74 families) feelings, perceptions, reactions to stresses, and satisfactions during a period of electronic home monitoring are reported. Data were collected during structured interviews by students in a graduate social work program. Although extreme anxiety was prevalent initially, only 27.4% of the parents felt they were very anxious beyond the first month. Social life was restricted in 55.7% but job attendance was seldom affected. Only four parents felt very irritated by the increased demands of the monitored baby. The majority (72.9%) said that the monitor made them feel more comfortable with their baby. Only 14.2% felt that their marriage relationship worsened during the period of monitoring; two couples separated. Most supportive to parents were their spouses, least supportive were friends and relatives. With availability of a psychosocial support system, electronic home monitoring of infants can be conducted by parents without constant and extreme anxiety and, in their judgment, can even be a satisfying experience.

Astrocytoma in an infant with prolonged apnea.

A 4-week-old infant experienced prolonged central sleep apnea requiring resuscitation. At 6 months of age he developed episodic obstructive apnea (diagnosed as laryngospasm by direct laryngoscopy) with an abnormal EEG and a normal computed tomography (CT) scan, and at 14 months of age he developed hemiparesis due to a gemistocytic astrocytoma grade III-IV. Following removal of the mass, he has had occasional seizure activity, but no further episodes of obstructive apnea.

Care of infants with near-miss sudden infant death syndrome.

The purpose of this study was to evaluate the effectiveness of home management of life-threatening apnea in infants with near-miss sudden infant death syndrome (SIDS). A total of 84 infants were monitored with apnea monitors for an average of seven months (range 1 to 27). A group of 27 infants had episodes of apnea requiring resuscitation during home monitoring, all of whom were successfully resuscitated by their parents on at least one occasion using bag and mask resuscitation, and 17 infants required more than one resuscitation. Subsequent resuscitation was unsuccessful with four infants. Infants who experienced more than ten episodes of prolonged sleep apnea (apnea longer than 20 seconds) during home monitoring had a significantly increased risk of requiring resuscitation than other infants being studied. With the use of home monitoring of these infants and parents trained in cardiopulmonary resuscitation, the survival rate was 93.4%.

Pediatricians' attitudes affecting decision-making in defective newborns.

A questionnaire designed to identify the factors that influence the resolution of ethical dilemmas was returned by 230 (57% of the total) Massachusetts pediatricians. The decision to recommend surgery for an infant with Down's syndrome with duodenal atresia when the parents had refused surgery was influenced by religious affiliation (P less than .01), religious activity (P less than .04), and sex (P=.05). Of those favoring surgery, 40.2% would pursue a court order. The decision to recommend surgery for an infant with severe meningomyelocele when the parents' position was not stated was influenced by age (P less than .01), religious activity (P less than .02), and specialization (P less than .008). When the parents' wishes were expressed, the majority of the pediatricians modified their decision in accord with these wishes. In response to general ethical questions, 79.6% of all pediatricians thought that parents should have the right to withold consent for surgery. Equal numbers thought that psychosocial reasons justified witholding lifesaving procedures. Among a variety of factors, they thought that willingness of the parents to care for the child would influence the decision to take heroic measures. There were 90.4% who thought that ethics should be part of medical education; 55.7% indicated this need throughout their careers.

Pulmonary edema associated with croup and epiglottitis.

Two children, ages 9 and 2 1/2 years, with clinical diagnoses of laryngotracheitis (croup) and epiglottis, respectively, developed florid pulmonary edema without evidence of cardiac enlargement. Both children responded to vigorous therapy, which included endotracheal intubation, mechanical ventilation with high oxygen concentrations and positive end expiratory pressure, diuretics, and support of the intravascular volume with colloid infusions. Swan-Ganz catheterization was performed in the child with epiglottitis to elucidate any hemodynamic malfunction. Pulmonary artery occluded pressure was found to be normal. We postulate that pulmonary edema may be the result of any of three major physiologic alterations: alveolar hypoxia, increased alveolar-capillary transmural pressure gradient, and a catechol-mediated shift of blood volume from the systemic to the pulmonary circulation. These alterations acting in concert would increase the volume of blood presented to the pulmonary capillaries, the pore size in those capillaries, and the hydrostatic pressure gradient promoting transduation. Failure of pulmonary lymphatics to effectively clear this fluid would result in pulmonary edema. Although pulmonary edema associated with acute upper airway obstruction is unusual, physicians should be altered to its possible appearance and the need for early and vigorous therapeutic measures.

Familial vocal cord dysfunction.

Vocal cord paralysis is a common cause of neonatal stridor. Familial vocal cord dysfunction, however, is unusual. All three siblings in one family had neonatal stridor. Vocal cord dysfunction was confirmed after endoscopic examination in two of the children; a temporary tracheotomy was required by one child. Results of evaluation, including pulmonary function tests, suggest discrete dysfunction localized to the neuromuscular pathway responsible for vocal cord abduction. Endoscopy is of prime importance in the diagnosis of vocal cord dysfunction. In considering therapy, the physician must weigh both the potentially life-threatening nature of vocal cord paralysis, as well as the likelihood of eventual spontaneous resolution of many familial and idiopathic cases.

Chemoreceptor function and sleep state in apnea.

Resting ventilation and ventilatory responses to 100% oxygen and to 5% carbon dioxide in air were measured in REM and non-REM sleep in post-neonatal infants. Normal controls were compared to infants with prolonged apnea and to siblings of sudden infant death victims. No significant differences in ventilatory responses were found between the groups. We conclude that apnea may occur in infants whose central and peripheral chemoreceptor activity is normal while they are breathing.

Infantile lobar hyperinflation: expectant treatment.

Arterial blood gases and regional lung function, measured with a 133xenon technique, were used to evalute the physiological defects and follow the natural history of 16 infants with lobar hyperinflation ("emphysema"). Hypoxemia was due to V/Q inequality at rest. Worsening of hypoxemia (mean Pao2 delta--26 mm Hg) with crying was due to shunting as a consequence of cessation of ventilation in the involved lobe. Surgery was necessary in three patients. Two deaths were caused by bronchopulmonary dysplasia after respiratory distress syndrome (RDS). In 12 of 14 infants, lung function was normal between the ages of 5 days and 1 year. Pediatrics, 59:1012-1018, 1977, LOBAR EMPHYSEMA, BLOOD GASES, REGIONAL LUNG FUNCTION.