Measurement of meperidine-induced respiratory depression using a new non-invasive technique.

Inductive plethysmography was used to assess the magnitude and duration of respiratory depression caused by doses of meperidine commonly administered during dental intravenous sedation. Minute volume measurements exhibited a high degree of accuracy when compared to simultaneous spirometry. Intravenously administered meperidine 25 mg/70 kg and 50 mg/70 kg both caused a significant shift to the right in their respective ventilatory-pco(2) response curves. The magnitude and duration of this respiratory depression was dose related. Even relatively low doses of meperidine used in dental intravenous sedation cause respiratory depression.

Measurement of tidal breath by determination of chest wall volume displacement in patients with airflow obstruction.

We compared tidal volume (VT) measured from the integrated airflow signal of a pneumotachygraph (PNTG) in ten patients, seated comfortably, with airway obstruction to VT, recorded simultaneously, by three chest-wall volume-displacement methods: two-channel magnetometer, isovolume calibration (mag-isov); respiratory inductance plethysmograph, isovolume calibration (rip-isov); and, inductance plethysmograph, least squares calibration (rip-l sq). There was no difference between VT, measured without PNTG, with each of the methods. When mouthpiece, noseclips, PNTG, and finally, dead space were included in a breathing circuit, VT increased to approximately one and one-half times that measured without the mouthpiece. Inspiratory volumes were measured with similar error by each method (mag-isov, 8.61 +/- 5.73 percent SD; rip-isov, 9.30 +/- 6.12 percent SD; rip-l sq, 8.43 +/- 6.27 percent SD). We conclude that in airway obstruction patients seated in a constant position, over the range of inspiratory volumes studied, error associated with chest wall volume-displacement methods is no greater than in normal subjects.

Pathologic pulmonary findings in children with the acquired immunodeficiency syndrome: a study of ten cases.

Lung tissue and tissue from the lymphoreticular system obtained at open biopsy and/or autopsy were studied in ten children with the acquired immunodeficiency syndrome (AIDS). One or both parents of nine of the children had AIDS or risk factors for AIDS. The remaining child had hemophilia. The following pulmonary lesions were seen: 1) diffuse alveolar damage (DAD), 2) Pneumocystis carinii and/or cytomegalovirus pneumonitis, 3) lymphoid interstitial pneumonitis (LIP), and 4) desquamative interstitial pneumonitis (DIP). Combinations of such factors as mechanical ventilation, oxygen therapy, and opportunistic infection played a role in the pathogenesis of DAD. Opportunistic infections were related to the defective cell-mediated immunity in these children. The clinical, epidemiologic, immunologic, and pathologic features of the thymuses of these patients indicate that the immune deficiency was unlikely to have been of congenital origin. The immunologic abnormalities may also have been related to the pathogenesis of LIP and DIP. Neither LIP nor DIP has been described in adults with AIDS. Open lung biopsy is of practical importance in the diagnosis and treatment of pulmonary disease in children with AIDS.

Alveolar hypoventilation and cor pulmonale associated with chronic airway obstruction in infants with Down syndrome.

Four infants with Down syndrome developed cor pulmonale and heart failure in association with chronic upper airway obstruction. Features of the sleep apnea syndrome were conspicuous; namely, noisy breathing with retraction, cyanosis and frequent apnea during sleep, and daytime lethargy and somnolence. The clinical picture masqueraded as cyanotic congenital heart disease. Arterial blood gas analyses revealed alveolar hypoventilation, especially during sleep. The nature of the obstructive element was variable. Adenoidectomy provided partial relief in one patient, and tonsillectomy and adenoidectomy resulted in temporary improvement in two others. Three patients were markedly benefitted by tracheostomy. Functional inspiratory pharyngeal closure was demonstrated fluorographically in one patient. Infants with Down syndrome may be predisposed to upper airway obstruction by virtue of hypoplasia of facial and oropharyngeal structures and generalized hypotonia. Additional obstructive elements may be contributed by hypertrophied lymphoid tissue, excessive secretions, and glossoptosis. Removal of the obstructive element is helpful, but functional obstruction may only be relieved by tracheostomy.

Sleep apnea in a child with the pickwickian syndrome.

A 3-year-old girl with a history of excessive weight gain from birth presented with obesity, somnolence, and cyanosis, characteristic of the Pickwickian syndrome. Obesity was familial and exogenous without endocrine or neurologic anomaly. Respiratory center sensitivity to carbon dioxide was normal. Excessive somnolence was due to the obesity, which during sleep caused airway obstruction, apnea, and awakening, finally resulting in sleep deprivation. The sleep apneas and the daytime somnolence disappeared with weight reduction, showing that obesity alone had been responsible for the disorder.

Lung elasticity and airway dynamics in Peruvian natives to high altitude.

To evaluate the role of genetic and environmental factors in the genesis of large lungs in high-altitude natives, we measured forced vital capacity (FVC), static lung pressure-volume characteristics and maximum expiratory flow-volume loops in 17- to 20-yr-old Peruvian natives to 3,850 m (highlanders) and 800 m (lowlanders). Forced vital capacity was 5.11 +/- 0.64 liters in highlanders, 116 +/- 11% of predicted; and 3.73 +/- 0.32 liters in lowlanders, 84 +/- 7% of predicted. Lung elastic recoil at functional residual capacity and at total lung capacity, and size-corrected pressure volume curves were similar in the two groups. Despite the larger volumes in highlanders, density-corrected maximum flow rates were similar in highlanders and lowlanders, and flow expressed in FVC'S-S-1 was less in highlanders. Upstream conductance at 50% FVC expressed in fvc's-s-1-cmH2O was 0.094 +/- 0.023 in highlanders vs. 0.147 +/- 0.050 in lowlanders. Flow rates did not change in sojourners to altitude, suggesting that the lower values of highlanders were due to anatomic factors. These findings suggest that airways, which form in fetal life, do not participate in adaptation to altitude, and that the large lungs of highlanders result from postnatal environmental hypoxic stimulation of lung growth. Our results illustrate the importance of "dysynaptic" lung growth in determining patterns of adult lung function.

Periodic apnea, exercise hypoventilation, and hypothalamic dysfunction.

Periodic apnea and exercise hypoventilation were observed in a 14-year-old boy. Hyperphagia, obesity, serum hyperosmolality without diabetes insipidus or appropriate thirst, and retardation of growth and sexual development indicated a hypothalamic disorder. Neurologic evaluation was normal except for electroencephalographic changes induced by apnea. Pulmonary function tests, resting arterial blood gases in the wakeful state, and ventilatory response to inhaled CO2 were also normal. Acute hypoxemia and respiratory acidosis occurred with apnea during sleep and with insufficient ventilation during exercise. The central origin of sleep apneas was shown by esophageal pressure monitoring. The hypothalamic dysfunction and exercise hypoventilation distinguish this patient from others with obesity and periodic apnea.