Transcutaneous monitoring as trigger for therapy of hypoxemia during sleep.

Based on results on central chemosensitivity in cats, paired stimuli were applied for therapy to infants with central respiratory insufficiency of various degrees. An unspecific respiratory stimulus, e.g.

Role of chemical afferents in the maintenance of rhythmic respiratory movements.

In seven anesthetized cats central chemosensitivity was eliminated (cold block) and peripheral chemoreceptors were either stimulated or eliminated (sectioned) to test whether nonchemical vagal afferents can maintain rhythmic ventilation and to determine the relative contribution of the carotid and aortic chemoreceptors to ventilatory drive without central chemosensitivity. Elimination of all chemical afferents invariably induced apnea, whereas ventilation was reduced from 533 to 159 ml X min-1 during cold block of central chemosensitivity and to 478 ml X min-1 after sectioning both sinus nerves. Cold block with only the aortic chemoreceptors and vagal afferents intact produced apnea in four of six cases tested.

Respiratory response to hypoxia and hypercapnia after elimination of central chemosensitivity.

Central respiratory drive responding to pH changes was eliminated by bilateral coagulation or cold block of area S (intermediate area) on the ventral medullary surface in 7 anaesthetized cats. Arterial pH, PCO2, and PO2 (4 cats) and the respiratory response to hypoxia and hypercapnia (6 cats) were observed before and after coagulation. After coagulation in hyperoxia the arterial pH dropped from 7.

Elimination of central chemosensitivity by coagulation of a bilateral area on the ventral medullary surface in awake cats.

Breathing and respiratory response to CO2 were observed in 6 awake cats and 1 control before and after bilateral coagulation of the formerly described area S (Schläfke and Loeschcke, 1967) on the ventral medullary surface under hyperoxic conditions. Ventilation decreased, PCO2 rose and CO2 response was almost or completely abolished in 4 cats, and moderately reduced in 2 cats. Inhalation of CO2 had an inhibitory effect on ventilation in two cases.

'Specific' and 'non-specific' stimuli in the drive of respiration.

In decerebrate and awake cats it was shown that central chemosensitivity can be blocked by cooling or coagulating bilaterally a formerly described area on the ventral medullary surface of cats, called area S. Such a procedure is followed by apnoea under the condition that vagi and sinus nerves are cut. With either vagi, sinus nerves, or central chemosensitivity intact respiration can be influenced by noise, touch, and electrical stimulation of dorsal roots, femoral nerves, and pontine reticular formation.