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CONTROL OF BREATHING DURING CORTICAL SUBSTITUTION OF THE SPONTANEOUS AUTOMATIC RESPIRATORY RHYTHM
Author(s) -
haouzi philippe,
chenuel Bruno,
whipp Brian
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.lb124-b
Subject(s) - ventilation (architecture) , rhythm , dead space , respiratory system , respiration , respiratory minute volume , respiratory rate , medicine , control of respiration , anesthesia , physics , anatomy , heart rate , blood pressure , thermodynamics
The central rhythm pattern generators for respiration (CPGs) transmit their rhythmic activity to bulbo‐spinal neuronal networks to produce the final motor ouput to the respiratory muscles. The question remains however whether the neurogenesis of eupnea is the consequence of the breath timing imposed by the CPGs or it relies on intrinsec properties of the respiratory bulbo‐spinal neurons, regardless the structures imposing the ventilatory timing. To address this question, human subjects were studied during a paced ventilation, produced by a voluntarily triggered breathing, bypassing therefore the rhythm imposed by the central pattern generators (CPGs). We demonstrated that when frequency of voluntarily triggered breaths was changed in an imperceptible ramp‐like manner (from 6 to 20 c/min), the resulting breath magnitude (VT) was strongly correlated to the breath duration (TTOT) (slope : 6,50 ± 2.91 l/min) but with a positive intercept on the VT axis (238± 112 ml) i.e. VT=V’A.TTOT+VD (V’A=alveolar ventilation, VD: dead space). Consequently, the ventilatory output was dependent on f induced dead space ventilation changes, maintaining PETCO2 constant. Humans possess a centrally set program for generating combinations of respiratory cycle durations and magnitudes at which the resulting minute ventilation properly matches metabolic demand, taking into account the variation of deadspace ventilation induced by f.