Effects of exercise at high altitudes on young adults.

Outward Bound programs are carried out throughout the world, and many of these courses occur at altitudes above 3000 m (10,000 ft). As more knowledge is accumulated about health problems at high altitudes, exercise has been implicated as a factor contributing to acute mountain sickness in susceptible individuals. Thus, exercise conditioning programs occurring at high altitudes have come under scrutiny. Twenty-eight young men and women were enrolled in an Outward Bound course at an altitude over 3000 m for a 21-day period. Twelve of the 28 individuals developed shortness of breath, cough, or both by the third day of the course. Of these 12, seven had pulmonary function abnormalities: three having evidence of large airway involvement and four having findings of small airway involvement. The symptoms were not significant enough to interfere with acclimatization and the muscular conditioning aspects of the program. Although at altitudes between 3000 m and 4300 m, pulmonary function abnormalities of acute mountain sickness develop in a significant number of participants, the abnormalities were not significant enough to prevent persons from completing the course or achieving marked improvements in fitness measurements.

Emergency treatment of foreign-body obstruction of the upper airway in children.

Recently, the Committee of Accident and Poison Prevention of the American Academy of Pediatrics presented its recommendations regarding the emergency management of the choking child. Renewed interest was stimulated in the controversy regarding whether back blows, abdominal thrusts, or chest thrusts should be used in the initial treatment of foreign-body obstruction of the upper airway. Two cases exemplifying problems in patient management are presented as a basis of focusing on the current controversy. Review of the clinical and experimental data suggests that back blows, followed by either chest or abdominal thrusts, are a reasonable approach to emergency airway obstruction, but that this recommendation is based on limited evidence.

Serial changes in pulmonary functions in children hospitalized with cystic fibrosis.

Pulmonary functions were serially measured in 17 children hospitalized with cystic fibrosis (CF) to determine how much and when pulmonary functions improved during 14 days of inpatient treatment. Absolute lung volumes and forced expiratory flows were recorded every other day while patients received chest physiotherapy, antibiotics, and bronchodilators. Vital capacity first improved after the fifth hospital day coincidentally with a reduction in residual volume and an increase in peak expiratory flow rate. Significant improvements in other pulmonary functions developed later in the hospitalization. Improvement in most pulmonary functions continued throughout the hospitalization and was maintained 2 wk after discharge. Improvement was less and uniformly developed later in those children with severe lung disease on admission (NIH score less than 50) compared with those with moderate respiratory involvement (NIH score greater than 50). Pulmonary function measurements may prove useful in determining the optimal duration of treatment for patients who are hospitalized with CF.

A dual approach to tracheobronchial foreign bodies in children.

From 1974 to 1980, 57 consecutive cases of children with tracheobronchial foreign bodies were treated by a new protocol in which peripherally located foreign bodies were treated nonoperatively and centrally located foreign bodies were removed bronchoscopically. Bronchoscopic removal was ultimately successful in all of the 29 children in whom the foreign body was located in the trachea or mainstem bronchus. There were eight minor complications, and in three instances it was necessary to repeat the bronchoscopy for retained fragments. In the other 28 children the foreign body was located in the segmental or lobar bronchi, and initial treatment consisted of a program employing inhalation bronchodilators, pulmonary drainage, and thoracic percussion. Treatment was successful (foreign body coughed out) in 18 patients (64%). Of the other 10 children subsequent bronchoscopy was successful in eight and failed in two patients. Of the latter patients, one required bronchotomy, and the other coughed out the foreign body. There were no deaths, major complications, or permanent pulmonary damage in either treatment series.

Selenium: childhood poisoning and cystic fibrosis.

Two cases of selenium ingestion in children are described; one child with severe cystic fibrosis died. Both children had cystic fibrosis and both had low serum chloride in association with selenium usage. Neither child was exposed to excessive heat or cold weather, factors known to salt-deplete children were cystic fibrosis, although one child was dehydrated during a summer month on initial presentation. One child had protein-calorie malnutrition, a condition known to enhance selenium toxicity in animals. We conclude that selenium is a potential hazard in its use as a health food fad for children with cystic fibrosis and in overdose ingestions. Thus selenium supplementation may have contributed to the morbidity and mortality reported here.

Intravenous aminophylline in patients with cystic fibrosis. Pharmacokinetics and effect on pulmonary function.

Intravenous aminophylline was administered to ten patients with cystic fibrosis (CF) to determine if the medication would improve pulmonary function and to study theophylline pharmacokinetics. Intravenous normal saline was given on another day as a control. Thoracic gas volume and airway resistance, measured in a volume displacement body plethysmograph, and maximal expiratory flow-volume curves were performed before and after each infusion. No significant improvement was noted in pulmonary function after normal saline infusion. Following aminophylline infusion. Following aminophylline infusion, significant improvement in thoracic gas volume, residual volume, specific airway conductance, and maximal expiratory flow at 60% of total lung capacity was noted. The pharmacokinetic analysis revealed a mean half-life of 4.7 hours, a total clearance of 91 mL/hr/kg, and a volume of distribution of 574 mL/kg. Intravenous aminophylline can acutely decrease airway obstruction in children with CF.

Re-evaluation of birth weights at high altitude. Study of babies born to mothers living at an altitude of 3,100 meters.

Babies born at altitudes above 2,700 meters have been reported to be below normal birth weight and small for gestational age (SGA). In a study of a specific community (Leadville, Colorado, altitude 3,100 meters) over a period of 14 months (ending November, 1978), 215 newborn infants were found to be appropriate for gestational age (AGA), with the entire group having a mean birth weight (3.16 kilograms) similar to that of newborn infants in Denver, Colorado (3.12 kilograms). This study from a community with a stable population indicates that babies born at high altitude are AGA. The increased morbidity which does occur for these babies is not due to SGA factors.

Endotracheal foreign bodies. Difficulties in diagnosis.

The diagnosis of foreign body aspiration into the lower airway depends primarily on the radiographic demonstration of partial bronchial obstruction causing localized air trapping or atelectasis, present in 95 per cent of the cases. Endotracheal foreign bodies may often be visualized directly on high kilovoltage radiographs of the airway of the airway or by fluoroscopy. In three of the four cases presented in this report, radiologic evaluation was normal, but endotracheal foreign bodies were subsequently demonstrated endoscopically. Foreign objects may remain in the trachea for prolonged periods of time, causing persistent coughing, wheezing, or stridor. When there is a clear history or strong suspicion of foreign body aspiration in a patient with persistent symptoms, bronchoscopy should be used for diagnosis and treatment.

Effects of hypoxia on respiratory control in neonates at high altitude.

The respiratory responses to acute hypoxia were investigated in 21 newborn infants in Leadville, CO. Time-related changes in pulmonary ventilation (VE) described four distinct phases to the hypoxic response characterized by an abrupt initial decrease (phase I), a transient subsequent increase (phase II) and decrease (phase III), and a further transient decrease upon termination of the hypoxic challenge (phase IV). Based on the degree of respiratory stimulation during phase II, the subjects were divided into two groups, "responders" and "nonresponders." In both groups in VE were attributed to variation in tidal volume (VT), inspiratory duration (TI), and breath duration being little affected. The latter indicated an absence of vagal volume-related modulation of respiratory pattern. In all subjects, a fixed linear function described the relationship between the mean inspiratory flows at 0.3 s after inspiratory onset (i.e., V0.3/0.3) ant at end inspiration (i.e., VT/TI). Thus, changes in respiratory output with hypoxia are attributed to variations in both the "gain" and "shape" of the inspiratory drive.

Intravenous linoleic acid supplementation in children with cystic fibrosis.

Ten children with CF in matched pairs were infused with either Intralipid or with 10% glucose on a double blind basis every other week for one year. Although statistically there was significantly greater gain in height and weight in the study year compared to the previous year only for the test group, both groups improved more than expected. Cumulative data analysis showed greater improvement for the Intralipid group (23 of a possible 45 points) compared to the glucose group (-2 points; P less than .02). This study indicates the need to better define the role of nutrition in the pathophysiology of CF. Meanwhile, it is recommended that all children with CF have plasma linoleic acid levels measured at least once yearly, and if levels are low, appropriate supplements should be given.

Partial obstruction of endotracheal tubes in children: incidence, etiology, significance.

We examined 99 endotracheal tubes removed from 81 pediatric patients to determine the incidence of partial endotracheal tube obstruction and predisposing factors. The overall incidence of obstruction was 20.2% (20/99); 14 of the 20 obstructed tubes were occluded less than 50%. General anesthesia during the period of intubation was the only factor significantly associated with an increased incidence of obstruction (p less than 0.05). There was no correlation of obstruction with duration of intubation, the presence of a Murphy-eye side hole, or small tube size. Among the 71 tubes from patients who received general anesthesia, a tube size of 4 mm or less was associated with an increased incidence of obstruction (p less than 0.05). Pressure-flow curves for three different sizes of endotracheal tubes were constructed to determine the increase in resistance produced by different degrees of obstruction. At flow rates that approximated those found in children during quiet breathing, the resistance of tubes that were 50% obstructed was 4 times greater than that found in unobstructed tubes.

Nebulized racemic epinephrine by IPPB for the treatment of croup: a double-blind study.

Racemic epinephrine has been advocated for the treatment of croup, but controlled studies have not proved it more effective than saline. Twenty patients (aged 4 months to 5 years) hospitalized with acute croup and persistent inspiratory stridor at rest were randomly assigned to one of two treatment groups: saline or racemic epinephrine, both nebulized and delivered by intermittent positive pressure breathing. Clinical scores were significantly improved (P less than .01) at ten and 30 minutes following the treatment with racemic epinephrine but not at 120 minutes. Racemic epinephrine was significantly more effective than saline at 10 (P less than .01) and 30 minutes (P less than .05) but not at 120 minutes after the treatment. We conclude that nebulized racemic epinephrine is effective treatment for the acute signs of croup.

Home management of bronchopulmonary dysplasia.

Home oxygen was utilized in six infants with BPD with no complications. This program allowed for early discharge of the infants, resulting in a mean financial savings of $18,000 per infant and a more normal family environment for the babies.

Respiratory failure associated with familial depression of ventilatory response to hypoxia and hypercapnia.

Respiratory failure has been associated with depressed ventilatory responses to hypoxia or hypercapnia or both. The possibility that familial factors are responsible for decreased chemosensitivity prompted this study of a child with unexplained respiratory failure and normal lung function. We found his ventilatory response to hypoxia and hypercapnia to be virtually absent. Studies of six healthy immediate family members (parents and siblings) showed that hypoxic response, as measured by an index of the relation between ventilation and hypoxia (index A), was consistently reduced: 45 +/- 8.7 S.E.M. (normal, 127 +/- 8.7) (P less than 0.005). Response to hypercapnia, measured as the slope of the ventilatory response to hypercapnia, was lower than normal, averaging 0.95 +/- 0.16 liters per minute per millimeter of mercury (normal, 1.76 +/- 0.13) (P less than 0.01). The patient's respiratory failure seemed related to deficient ventilatory responses to hypoxia and hypercapnia. It seems likely that this depressed hypoxic response is of familial origin.

Management of life-threatening asthma with intravenous isoproterenol infusions.

Thirty-four patients with life-threatening childhood status asthmaticus were treated with intravenous isoproterenol infusions. Twenty-seven responded favorably; seven failed to respond and underwent mechanical ventilation. Intravenously administered isoporterenol was a useful therapeutic adjunct in the treatment of these severe attacks. Complications in these cases were rare, but cardiac arrhythmia, rebound bronchospasm, and acute mobilization of secretions need to be considered. Further evaluation of the efficacy of intravenous infusions of isoproterenol in status asthmaticus would be valuable.