Oxygen consumption (V̇O2) was measured during hypoventilation induced by moderate-sized flow-resistive loading in 12 preterm infants, and the results were compared with those obtained under basal conditions immediately before and after the loaded run, each of which lasted for 7-10 min. Loading was performed with a continuous flow-resistive load (inspiratory and expiratory), which was approximately threefold greater in magnitude than the intrinsic resistance of preterm infants. V̇O2, minute ventilation (V̇E), transcutaneous oxygen tension (Ptc(O2)), and transcutaneous carbon dioxide tension (Ptc(CO2)) were continuously monitored. Results revealed that V̇E decreased significantly with loading, from 336 ± 103 to 231 ± 58 (SD) ml · min-1 · kg-1 (P < 0.001), while returning to basal levels of 342 ± 59 ml · min-1 · kg-1 after discontinuation of the load. V̇O2 decreased from 7.2 ± 1.2 to 5.9 ± 0.9 ml · min-1 · kg-1 with loading (P < 0.001) and returned to 7.2 ± 1.2 ml · min-1 · kg-1 at the second basal measurement. Ptc(O2) remained unchanged with loading, and Ptc(CO2) only increase from 39 ± 8 to 41 ± 9 Torr (P < 0.05) with loading, while returning to 40 ± 9 Torr at the second basal measurement. Results indicate a decrease in the metabolic rate and ventilation with loading, with relatively little increase in Ptc(CO2). These data can explain prior observations that minimal disturbances in oxygen and carbon dioxide tensions occur with hypoventilation during flow-resistive loading in neonates, although the precise mechanism for this reduction remains to be determined.
- minute ventilation
- oxygen consumption
ASJC Scopus subject areas
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation