Short-term holding room treatment of asthmatic children

We undertook a randomized trial to compare holding room treatment vs hospitalization of patients with childhood status asthmaticus. Two thirds of 51 patients were discharged from a holding room within 24 hours (mean 11.8 +/- 4.61 hours); the others required hospitalization. One third of 52 hospitalized patients received less than or equal to 1 day of intravenously administered therapy, and two thirds received less than 2 days of therapy (mean 45.6 +/- 12 hours). There were no statistically significant differences in recurrence rates between the two groups in the 28 days following status asthmaticus. For patients receiving less than or equal to 1 day of therapy, the holding room cost was $526 +/- $226 vs $1439 +/- $339 for hospitalized patients (P less than 0.001). Thus, holding room therapy for childhood status asthmaticus is both medically and economically effective.

Respiratory problems in foals

Despite major advances in our knowledge and ability to treat respiratory diseases in neonatal foals, neonatal respiratory medicine is still in its infancy. It is hoped that this article may serve as a guideline for diagnosis and treatment. Specific antibiotic regimens and emergency procedures are covered in other articles in this symposium. Because management factors play a critical role in the pathogenesis of respiratory disease, education of clients as to their importance would help both prophylactically and therapeutically. The necessity of very careful monitoring of neonates, which is critical to early detection of disease, should be stressed. As respiratory diseases can be fulminant and rapidly fatal, it is imperative not to delay diagnosis and therapy. Thorough examination and implementation of appropriate diagnostic techniques, as well as prompt early referral to a more sophisticated facility when indicated, would prevent many deaths. Although sophisticated support systems are vital for survival of some of these foals, good basic intensive nursing care combined with selection of appropriate drug therapy very early in the course of the disease is all that many foals require and can significantly improve survival rates.

Aminophylline versus doxapram in idiopathic apnea of prematurity: a double-blind controlled study

A double-blind controlled study, in two parts, was undertaken to compare the effectiveness of aminophylline and doxapram therapy in idiopathic apnea of prematurity. In the first part of this study, eight of 15 infants responded to doxapram therapy with complete cessation of apneic spells and six of 11 infants responded similarly to administration of aminophylline. These differences were statistically insignificant. In the second part of the study, assessment was made of whether the addition of doxapram to aminophylline therapy was effective in treatment of apnea of prematurity that had been unresponsive to aminophylline alone. Of ten infants who continued to have apneic spells during treatment with aminophylline, eight responded to the addition of doxapram with complete cessation of apnea. Nine infants received placebo in addition to aminophylline, and none had a reduction in frequency of apnea.

Pathophysiology and treatment of sleep apnea

The sleep apnea syndromes have attracted the interest of physicians and scientists in many different disciplines because the disorders involve the physiology of sleep, the control of respiration, the function of the upper airway, and the clinical sequelae upon cardiac, pulmonary, and psychological function. Over the eight years since this subject was last reviewed here (1), the pathophysiology of obstructive sleep apnea has become better understood. A variety of new treatments are now available. However, our clinical knowledge of the syndrome and its natural history have changed little. The high prevalence of these syndromes and related disorders such as snoring is only beginning to be apparent. This chapter reviews current understanding of these syndromes, with particular emphasis on recent advances, and highlights questions for future investigation. First, we consider normal upper airway function and the control of breathing during sleep. Then, we apply this information to a consideration of the pathophysiology, clinical features, and treatment of sleep apnea syndromes.

Aminophylline versus doxapram in weaning premature infants from mechanical ventilation: preliminary report

A small, double-blind crossover study compared the efficacy of aminophylline and doxapram in ventilator weaning of eight premature infants recovering from respiratory distress syndrome (RDS). Although neither drug was significantly better than the other, four infants were weaned from mechanical ventilation after drug administration. It is suggested that drugs stimulating the respiratory center may aid in shortening the duration of mechanical ventilation in premature infants recovering from RDS.

Aminophylline and its influence on ventilatory endurance in humans

The purpose of this study was to evaluate whether the previously demonstrated improvement in contractile tension of diaphragmatic muscle with aminophylline results in improved ventilatory endurance. We measured the maximal sustained ventilatory levels during prolonged isocapnic hyperpnea as an index of ventilatory muscle function. This measurement was made in 7 normal subjects and 7 patients with chronic obstructive pulmonary disease during the intravenous administration of saline and aminophylline on 2 separate days. The order of administration of the infusions was randomized. Although both groups showed slightly higher sustained ventilatory levels during aminophylline infusion, the magnitude of change was small and unlikely to have a significant clinical benefit in the setting of respiratory muscle fatigue.

Rectal aminophylline in the management of apnoea of prematurity

Rectal suppositories as an alternative to intravenous aminophylline in the management of recurrent apnoea were studied in 41 preterm infants of mean gestation 28.3 weeks and mean birthweight 1176 g. Therapeutic blood concentrations were obtained two hours after a rectal loading dose of 10 mg/kg, with steady concentrations and maximum reduction in apnoeic episodes (from a mean of 0.5 per hour to 0.09 per hour) within 24 hours on a maintenance dose of 10 mg/kg/day. There was good correlation between the rectal dose and the plasma theophylline concentration. Several infants showed a significant reduction in Pco2 when treated with aminophylline. Side effects were related to the plasma theophylline concentration and were not seen at concentrations less than 14 mg/l.

Adenosine antagonist aminophylline attenuates pacing-induced coronary functional hyperemia

The role of adenosine in pacing-induced hyperemia was examined in 10 dogs. Left coronary blood flow (LCBF), left ventricular O2 extraction [(a-v)O2], and myocardial O2 consumption (MVO2) were monitored. Heart rate (HR) was initially paced at 120 beats/min and then increased to 180 beats/min to elicit a hyperemic response (delta LCBF). During the hyperemia, the vasodilatory response to exogenous adenosine (FAd) was tested. HR was then returned to the initial level, and 20 min after injection of aminophylline (100 mg iv) HR was again increased to 180 beats/min. The response to adenosine was again tested. The pacing-induced increase in MVO2 (delta MVO2) was not affected by aminophylline (P greater than 0.05). However, after aminophylline, the flow response slope delta LCBF/delta MVO2 was decreased by about 20% (P less than 0.05), and the extraction-response slope delta (a-v)O2/delta MVO2 was increased by 100% (P less than 0.05). FAd was also decreased by aminophylline, and the magnitude of the reduction was correlated with the decrease in the flow-response slope (r = 0.82). These results suggest that endogenous adenosine may play an important role in coronary functional hyperemia induced by increases in heart rate.

Ventilatory control in asthma

Ventilation (liters of air per minute) increases during an acute attack of asthma. Hypocapnia is the rule, although eucapnia may occur. This suggests both that respiratory center output is increased and that acidemia is not the major stimulus to augmented respiration. Mechanical receptors responding to change in end-expiratory respiratory system volume or airway dimensions, cortical stimulation to the medullary respiratory centers, and possibly hypoxemia function in concert to regulate ventilation in asthma. Newer laboratory techniques permit independent assessment of chemical and cortical components of ventilatory drive. These techniques have provided fresh insights into the effects of various therapeutic interventions upon respiration in asthma.

Pharmacokinetic disposition of theophylline in horses after intravenous administration

The pharmacokinetics of theophylline were determined in 6 healthy horses after a single IV administration of 12 mg of aminophylline/kg of body weight (equivalent to 9.44 mg of theophylline/kg). Serum theophylline was measured after the IV dose at 0.25, 0.5, 1, 2, 4, 6, 8, 12, and 15 hours. Serum concentration plotted against time on semilogarithmic coordinates, indicated that theophylline in 5 horses was best described by a 2-compartment open model and in 1 horse by a 1-compartment open model. The following mean pharmacokinetic values were determined; elimination half-life = 11.9 hours, distribution half-life = 0.495 hours, apparent specific volume of distribution = 0.885 +/- 0.075 L/kg, apparent specific volume of central compartment = 0.080 L/kg, and clearance = 51.7 +/- 11.2 ml/kg/hr. Three horses with reversible chronic obstructive pulmonary disease were serially given 1, 3, 6, 9, 12, and 15 mg of aminophylline/kg in single IV doses (equivalent to 0.8, 2.4, 4.7, 7.1, 9.44, and 11.8 mg of theophylline/kg, respectively). The horses were exposed to a dusty barn until they developed clinical signs of respiratory distress and were then given the aminophylline. Effects of increasing doses on different days were correlated with clinical signs, blood pH, and blood gases. The 3 horses had a decrease in the severity of clinical signs after the 9, 12, or 15 mg doses of aminophylline/kg. The horses at 0.5 hour after dosing had a significant decrease in PaCO2 (43.6 +/- 5.5 to 39.4 +/- 6.7 mm of Hg, P less than 0.001) and a significant increase in blood pH (7.38 +/- 0.017 to 7.41 +/- 0.023, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of obzidan, tropaphen, adrenaline and euphylline on histamine bronchospasm in guinea pigs]

It has been demonstrated in experiments on guinea-pigs that the beta-adrenoblocker propranolol (1-2 mg/kg) substantially raises bronchial sensitivity to histamine (10 mg/kg). The alpha-adrenoblocker tropaphen (2 mg/kg) potentiates the protective action of adrenaline (5 micrograms/kg) and euphylline (8 mg/kg) in bronchospasm induced by histamine (10 micrograms/kg).

[Bioelectrical, biochemical and histomorphological changes in the ocular tissues in pituitrin hypertension and the use of euphylline and papaverine]

Experimental study on rabbits of bioelectric and biochemical characteristics of eye tissues during pituitrin hypertension and application of euphylline and papaverine as well as comparison of the data obtained indicate that during pituitrin hypertension, transtissue potential difference and density of short-circuit current in the lens are considerably increased whereas the level of tissue respiration in the eye is reduced. Administration of euphylline or papaverine during pituitrin hypertension aggravates hemodynamic disorders in eye tissues, deteriorates the bioelectric and biochemical characteristics in both hypertensive and control animals.

The antidiuretic hormone response to therapy for acute asthma

The plasma antidiuretic hormone concentrations in eight asthmatic children were measured at the onset of an acute severe attack and were repeated 24 h later. Conventional therapy and maintenance fluid intake resulted in a significant fall in antidiuretic hormone concentrations without abnormal changes in other biochemical indicators of dehydration.

Conditioning of the diaphragm with phrenic nerve stimulation after prolonged disuse

We studied the effect of electrical stimulation of the phrenic nerve on the force frequency relationship of the disused diaphragm. A high quadriplegic who had been totally ventilator dependent for 6 months following a C2 fracture received bilateral phrenic nerve stimulators. During a 6-wk period of conditioning by electrical stimulation, the force of diaphragm contraction was assessed by measurement of transdiaphragmatic pressures during stimulation of each nerve over a range of frequencies. Tidal volume as well as rib cage and abdominal motion were studied. There was an upward shift of the force frequency relationship of the diaphragm over the 4-month period of phrenic nerve pacing using repetitive stimulus trains of 14 to 28 Hz. This improvement appeared to plateau at about 11 wk. The increase in contractility was accompanied by a progressive diminution in the stimulus frequency at which fusion of the contraction occurred. The disused diaphragm, like other skeletal muscle, may be conditioned with electrical stimulation.

Cheyne-Stokes respiration revisited: controversies and implications

Investigation of the periodic crescendo-decrescendo alterations in tidal volume in Cheyne-Stokes respiration (CSR) has provided remarkable insight into the physiology of respiratory control. Many patients with periodic breathing have both cardiac and neurologic disease. Considerable controversy has surrounded determination of the relative importance of cardiac and neurologic mechanisms in the genesis of this breathing abnormality. Several investigators have considered the respiratory center as a chemostat model with three basic components: the controller system (chemoreceptors), the controlled system (gas tensions of O2 and CO2), and the feedback loop (arterial circulation from the lung to the brain). If the relationship between these cardiac and neurologic components is altered, stability of the respiratory control system is lost. Such disturbance in the control system may arise by prolongation of the circulation time, or by the system becoming more dependent on its O2, rather than the CO2 component. Earlier investigators considered periodic breathing as a forewarning of ominous developments. In recent studies, mild degrees of periodic breathing, easily missed on physical examination, are often found in otherwise normal subjects, particularly during sleep. Generally no therapy is required, although aminophylline, O2 or CO2 administration has been shown to abolish periodic breathing.