Respiratory patterns during progressive asphyxia in newborn rabbits

E. E. Lawson, B. T. Thach

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During acute progressive asphyxia an abrupt transition occurs from regular respiratory efforts to primary apnea and gasping. To study this transition the authors measured inspiratory duration (T(I)), expiratory duration (T(E)), maximal inspiratory tracheal pressure (P(max)), electromyographic activity (EMG) of different muscle groups, and the electrocorticogram (ECoG) of 3 to 5 day old rabbits following airway occlusion at functional residual capacity (FRC). The onset of primary apnea was associated with other central nervous system events as indicated by decerebrate posture and maximal EMG activity which were followed by relaxation, loss of EMG activity, and an isoelectric ECoG. Indices of inspiratory drive (P(max) and P(max)/T(I)) were preserved or accentuated following primary apnea despite a reduction of overall respiratory activity (frequency x P(max)). The onset of primary apnea appears to be due to interruption of the respiratory cycling controls rather than failure of the respiratory center which regulates inspiratory force. Gasping appears to be linked with progressive changes in respiratory patterns which are observed prior to primary apnea. These findings do not support the concept of a 'gasping' center.

Original languageEnglish (US)
Pages (from-to)468-474
Number of pages7
JournalJournal of Applied Physiology Respiratory Environmental and Exercise Physiology
Issue number3
StatePublished - Dec 1 1977
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Endocrinology


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