Effects of CO2 rebreathing on pulmonary mechanics in premature infants

Academic Article

Abstract

  • The effects of hypercapnia produced by CO2 rebreathing on total pulmonary, supraglottic, and lower airway (larynx and lungs) resistance were determined in eight premature infants [gestational age at birth 32 ± 3 (SE) wk, weight at study 1,950 ± 150 g]. Nasal airflow was measured with a mask pneumotachograph, and pressures in the esophagus and oropharynx were measured with a fluid-filled or 5-Fr Millar pressure catheter. Trials of hyperoxic (40% inspired O2 fraction) CO2 rebreathing were performed during quiet sleep. Total pulmonary resistance decreased progressively as end-tidal PCO2 (PET(CO2)) increased from 63 ± 23 to 23 ± 15 cmH2O · l-1 · s in inspiration and from 115 ± 82 to 42 ± 27 cmH2O · l-1 · s in expiration between room air (PET(CO2) 37 Torr) and PET(CO2) OF 55 Torr (P < 0.05). Lower airway resistance (larynx and lungs) also decreased from 52 ± 22 to 18 ± 14 cmH2O · l-1 · s in inspiration and from 88 ± 45 to 30 ± 22 cmH2O · l-1 · s in expiration between PET(CO2) of 37 and 55 Torr, respectively (P < 0.05). Resistance of the supraglottic airway also decreased during inspiration from 7.2 ± 2.5 to 3.6 ± 2.5 cmH2O · l-1 · s and in expiration from 7.6 ± 3.3 to 5.3 ± 4.7 cmH2O · l-1 · s at PET(CO2) of 37 and 55 Torr (P < 0.05). The decrease in resistance that occurs within the airway in response to inhaled CO2 may permit greater airflow at any level of respiratory drive, thereby improving the infant's response to CO2.
  • Authors

    Author List

  • Miller MJ; DiFiore JM; Strohl KP; Carlo WA; Martin RJ
  • Start Page

  • 2582
  • End Page

  • 2586
  • Volume

  • 70
  • Issue

  • 6