Near infrared spectroscopy-measured changes in cerebral blood volume and cytochrome aa₃ in newborn lambs exposed to hypoxia and hypercapnia, and ischemia: a comparison with changes in brain

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• 作者：Shadid ; Majidah ; Hiltermann ; Lennard ; Monteiro ; Louisa ; Fontijn ; Jehudith ; Van Bel ; Frank
• 关键词：Near infrared spectroscopy ; Brain perfusion and metabolism ; Newborn ; Hypoxia and hypercapnia ; Hypotension ; Δ ; CBV ; changes in cerebral blood volume ; CMR_O2 ; cerebral metabolic rate of O₂ ; Δ ; Cytaa₃ ; changes in cytochr
• 刊名：Early Human Development
• 出版年：1999
• 出版时间：June, 1999
• 年：1999
• 卷：55
• 期：2
• 页码：169-182
• 全文大小：329 K

文摘

Objectives: Validation of near infrared spectroscopy (NIRS)-measured changes in cerebral blood volume (ΔCBV) and cytochrome aa₃ (ΔCytaa₃) as estimators of changes in brain perfusion and oxygenation in the newborn lamb during hypoxia and hypercarbia, and additional hypotension. Methods and materials: In 33 newborn lambs brain perfusion assessed by carotid artery blood flow (ΔQ_car: ml/min)and cerebral metabolic rate of oxygen (ΔCMR_O2: ml O₂/min) were related to NIRS-derived ΔCBV (ml/100 g) and ΔCytaa₃ (μM) during combined hypoxia and hypercarbia and additional hypotension. Combined hypoxia and hypercapnia was induced by ventilation with 6–8 % of O₂ and 10 % of CO₂ during 30 min, and additional hypotension (<35 mmHg for 5 min) was induced by careful withdrawal of blood. Results: CBV increased during hypoxia and hypercarbia, decreased during additional hypotension and was related to ΔQ_car.: (0.009 ml/100 g change per ml/min Q_car: P<0.0001). Cytaa₃ increased during hypoxia and hypercarbia, decreased during subsequent additional hypotension and showed a reverse relationship with ΔCMR_O2 (−1.65 μM change per ml O₂/min CMR_O2: P<0.0001). Cytaa₃ remained above baseline during reperfusion. Conclusions: ΔCBV estimates changes in brain perfusion, but overestimates brain perfusion during hypotension. The pattern of ΔCytaa₃ suggests less oxygen utilisation by brain tissue during hypoxia and subsequent reperfusion.