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- Title
Increased systemic oxygen consumption offsets improved oxygen delivery during dobutamine infusion in newborn lambs.
- Authors
Penny, D. J.; Sano, T.; Smolich, J. J.
- Abstract
Objective: To determine: 1) if dobutamine elicited a thermogenic response during postnatal development; and 2) if this response impacted on the balance between systemic O2 delivery (DO2) and O2 consumption (VO2), and involved one or a combination of adrenoceptor subtypes. Design: Prospective non-randomized unblinded study. Setting: University research laboratory. Subjects: Thirty-five Border-Leicester cross lambs used in a main study performed at 1–2 days (n=7), 7–10 days (n=7), and 6–8 weeks (n=8), and in a adrenoceptor blockade substudy performed at 1–2 days (n=13). Interventions: Lambs were instrumented under anaesthesia and dobutamine was infused at incremental rates of 1–40 µg/kg per minute. In separate subgroups of 1–2 day-old lambs, dobutamine was infused after selective or combined α1, β1, and β2-adrenoceptor blockade. Measurements: Cardiac output, aortic and pulmonary arterial blood gases, and body temperature were measured. DO2 and VO2 were calculated. Main results: Dobutamine increased DO2 similarly at all three ages. Dobutamine also increased VO2 in the absence of muscle shivering, but the average rise in 1–2 day-old lambs was sevenfold to 12-fold greater (P<0.001) than in 7–10 day-old and 6–8 week-old animals, was associated with an increase in systemic O2 extraction, and accounted for ≈90% of the rise in DO2. Body temperature rose by 1.3±0.5 °C in 1–2 day-old animals (P<0.001), but was unchanged in 7–10 day-old or 6–8 week-old lambs. In 1–2 day-old lambs, rises in DO2, VO2, and body temperature induced by dobutamine were not affected by selective α1, β1 or β2 adrenoceptor blockade, but were markedly attenuated by combined adrenoceptor blockade. Conclusions: A substantial rise in VO2 which accompanied a pronounced thermogenic effect of dobutamine in newborn lambs utilized most of the associated increase in DO2 and appeared to be dependent on activation of multiple adrenoceptor subtypes.
- Subjects
ADRENERGIC receptors; BODY temperature regulation; OXYGEN therapy; DRUG receptors; SYMPATHETIC nervous system; PHYSIOLOGICAL control systems; BODY temperature; CRITICAL care medicine
- Publication
Intensive Care Medicine, 2001, Vol 27, Issue 9, p1518
- ISSN
0342-4642
- Publication type
Article
- DOI
10.1007/s001340101044