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CO2 expirograms during ERV expiration
Author(s) -
Rueda Luis Antonio,
Cruz Julio Cesar,
Caucha Luis Jhony
Publication year - 2009
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.23.1_supplement.1037.3
Subject(s) - expiration , apex (geometry) , tidal volume , dead space , apnea , functional residual capacity , lung volumes , pulmonary gas pressures , medicine , respiratory system , anesthesia , lung , anatomy
Expired CO 2 is usually recorded during normal breathing. There are few CO 2 records beyond functional residual capacity (FRC) (Flores & Cruz. Chest 102:438‐443, 1992). However, the effect of apnea upon expired CO 2 during the expiratory reserve volume (ERV) is not known. Thus, we are reporting CO 2 expired curves (see figure of one subject) during ERV expiration, after holding the breath at FRC for several seconds (8s to 33s) which include the expiration time. Five subjects provided a written consent to this study, which was approved by the IRB of the University. The pattern of the curves shown was similar in all subjects to the one presented. Initial PCO 2 values at 0s are the FRC end‐tidal values. The abrupt rise of CO 2 corresponds to the elimination of CO 2 from the dead space, followed by a waving alveolar plateau. The control curve agrees with Flores and Cruz (follows the model of West). With apnea, the expected increase in alveolar PCO 2 is evident. After 8s the alveolar plateau starts to rise (positive slope) and becomes flat at 33s. Finally, the behavior of the curves, during the last 2s of expiration, suggests that the apex‐to‐base CO 2 concentration difference is reversed. We must remember that the expirograms presented reflect the uneven emptying of parallel regions of the lung where the apical regions contribute more than the basal regions. Supported in part by ONG ‐ Centro de Enseñanza Investigación y Servicios.