PubMed Health⌕ Search

Biomedical subjects

F L Eldridge

Publications and source records attributed to F L Eldridge.

At least 91 records · Page 5Linked to original sources
PubMed1976

Expiratory effects of brief carotid sinus nerve and carotid body stimulations.

The expiratory response, measured directly as ventilatory volume and as internal intercostal or abdominal muscle EMG activity, to brief intermittent electrical stimulation of the carotid sinus nerve or chemical stimulation of the carotid body was determined in anesthetized cats. Stimuli given during expiration had a specific expiratory effect, manifested by increased expiratory duration, increased activity of expiratory muscles and increased depth of expiration. The later in expiration the stimulus was exhibited, the greater all effects became. Vagal section had no effect on the response and the duration of response persisted after spinal cord section at C7-T1. It is concluded that expiratory stimulations have effects on expiration similar to those on inspiration from stimulations given during inspiration. It is concluded that the mechanism operates at a brain stem level. However, because the latency of the response is much longer than the inspiratory response to the same stimuli, the pathway must be different.

Animals↗
PubMed1976

Central neural stimulation of respiration in unanesthetized decerebrate cats.

A previously reported central neural respiratory control process was restudied in unanesthetized decerebrate cats during spontaneous breathing, and during conditions of constant chemical stimulation where phrenic nerve activity was used to quantitate respiratory output. Respiration was increased by carotid sinus nerve stimulation. The pattern of respiration was examined at the cessation of such stimulation. In spontaneously breathing animals, active hyperventilation (HV) was followed by hyperpnea for up to 30 s and never by apnea. Passive HV was always followed by apnea. In animals with controlled chemical conditions, the transient at the end of stimulation consisted of two components, the first an immediate decrease in respiratory output and the second a slow decrease with a period of over 5 m. It is suggested that a facilitatory feedback process, probably located in the reticular activating system, maintains respiratory output for some time after cessation of a stimulus. This study duplicates the results of previous studies and shows that no area of the brain above the pons is required for the mechanism's operation.

Animals↗
PubMed1976

Sleep apnea in eight children.

Eight children, 5 to 14 years of age, were diagnosed by means of nocturnal polygraphic monitoring with a sleep apnea syndrome similar to that seen in adults. Excessive daytime sleepiness, decrease in school performance, abnormal daytime behavior, recent enuresis, morning headache, abnormal weight, and progressive development of hypertension should suggest the possibility of a sleep apnea syndrome when any of these symptoms is associated with loud snoring interrupted by pauses during sleep. Surgery may eliminate the clinical symptomatology.

Adenoidectomy↗
PubMed1975

[Can an anomaly of the central nervous system be responsible for hemodynamic disorders].

Twenty-seven subjects with insomnia or diurnal hypersomnolence presented a sleep apnea syndrome when their respiration was systematically checked during sleep. These sleep-induced respiratory abnormalities were completely occult and pulmonary function tests performed during wakefulness were normal. The patients, all non-obese, presented serious pulmonary artery pressure changes which were directly connected with the repetitive sleep apneas. Half of the patients also had systemic hypertension. Two children (aged 11 and 15) underwent tracheostomies which by-passed the sleep-induced obstruction. Systemic hypertension was reduced after surgery.

Adolescent↗
PubMed1975

Relationship between turnover rate and blood concentration of lactate in exercising dogs.

Steady-state blood lactate concentrationss and lactate turnover, or entry, rates were determined by use of constant infusion of L(+)-[14C]lactate in seven anesthetized dogs before and during electrically induced exercise. Lactate entry rates increased during exercise in all dogs with or without the infusion of additional exogenous cold lactate. Blood lactate concentrations, on the other hand, rose to levels considerably below those predicted for these entry rates in a previous study of the relationship in normal nonexercising dogs. It is concluded that improved efficiency of lactate removal during exercise allows low blood concentrations despite large increases in entry rates.

Animals↗
PubMed1975

Relationship between respiratory nerve and muscle activity and muscle force output.

To demonstrate the most satisfactory way of using electrical activities of respiratory nerves and muscles, activities of phrenic nerve and external intercostal muscle (ICM) and the airway pressure changes generated by respiratory muscle contraction were recorded in anesthetized cats during complete airway occlusion. Electrical activities were rectified, integrated and processed in terms of peak and average inspiratory rates per 0.1 s and of total activity per breath. Peak rate of phrenic nerve activity exhibited a high linear correlation (r = 0.974) with peak inspiratory pressure. Average phrenic rate showed a similar high correlation (r = 0.973). Peak rate of external ICM was linearly related to peak pressure but the correlation was less good (r = 0.915). Total phrenic activity per breath was too dependent upon inspiratory duration to be a satisfactory correlate (r = 0.674). In this experiment occlusion pressure was an index of muscle force generation and respiratory control system output. It is concluded that peak or average rates of phrenic activity provide an electrical index of output changes. On theoretical grounds, peak rate is probably better.

Airway Obstruction↗
PubMed1975

Sleep apnea syndrome. Can it induce hemodynamic changes?

Of 250 patients referred to the Stanford Sleep Disorders Clinic, 35 were diagnosed for a sleep induced apnea syndrome. Thirty of them (27 adults and 3 children) were nonobese and complained of a sleep disorder. In 12 patients (9 adults and 3 children) extensive cardiorespiratory workups were done during sleep and wakefulness. Three types of sleep induced apnea syndrome were identified: diaphragmatic (or central), obstructive and mixed. The diaphragmatic type was predominant in sleep apnea insomnia; obstructive was predominant in sleep apnea hypersomnia. Hemodynamic changes were documented during sleep. Tracheostomy, done in two cases, improved the sleep induced symptomatology.

Adult↗
PubMed1973

Insomnia with sleep apnea: a new syndrome.

A new clinical syndrome, sleep apnea associated with insomnia, has been characterized. Repeated episodes of apnea occur during sleep. Onset of respiration is associated with general arousal and often complete awakening, with a resultant loss of sleep. An important clinical implication is that patients complaining only of insomnia may be suffering from this syndrome.

Apnea↗
PubMed1972

The importance of timing on the respiratory effects of intermittent carotid sinus nerve stimulation.

1. The respiratory response, measured directly as tidal volume or indirectly by using integrated peak phrenic activity, to intermittent electrical stimulation of the carotid sinus nerve was determined in anaesthetized cats.2. Stimulation at rates of 20-25 Hz for 0.5 sec had a rapid effect, increasing inspiratory airflow and phrenic discharge, but only if applied during inspiration. An increase in tidal volume or peak level of integrated phrenic discharge occurred only if the stimulus was exhibited during the second half of inspiration. Continuous stimulation had no greater effect on size or frequency of breathing than did intermittent inspiratory stimuli alone. Stimulation during expiration had no effect on the form or magnitude of subsequent breaths.3. Stimuli in expiration led to a prolongation of expiration. Stimuli in late inspiration caused a prolongation of both inspiration and expiration. Because of these effects, the respiratory rate could be changed by stimulation; in some instances entrainment of respiration by the intermittent carotid sinus nerve stimuli occurred.4. The findings are attributable to modulation of incoming carotid sinus nerve information by the central respiratory neurones, which use primarily that which arrives during inspiration. They show a possible mechanism by which oscillating signals may have a different effect than their mean level would indicate.

Action Potentials↗