PaCO2 and cerebral blood flow

[GingerSue]

this is a brief explanation of cerebral blood flow:

there is a sentence in this paragraph from my textbook that somehow doesn't quite flow:

"The partial pressure of arterial carbon dioxide (PaCO2) is a potent vasoconstrictive agent. An increase in PaCO2 relaxes smooth muscle, dilates cerebral vessels, decreases cerebrovascular resistance, and increases CBF. ... A decrease in PaCO2 reverses this process and decreases CBF. Cerebral oxygen tension (PaO2) below 50 mm Hg results in cerebral vascular dilation. This dilation decreases cerebral vascular resistance and increases CBF.. If PaO2 is not raisesd, anaerobic metabolism begins, resulting in an accumulation of lactic acid. As lactic acid increases and hydrogen ions accumulate, the cerebral environment becomes more acidic. Within this acidic environment, further vasodilation occurs in a continued attempt to increase blood flow. The combination of a severly low arterial oxygen pressure (PaCO2) and an elevated hydrogen ion concentration (acidosis), which are both potent cerebral vasodilators, may produce a state wherein autroregulation is lost and compensatory mechanisms fail to meet rtissue metabolic demands."

- did they mean (PaO2) instead of PaCO2 in the above sentence or did they mean (increased PaCO2) - increased partial pressure of arterial carbon dioxide? (well, both increased PaCO2 and decreased PaO2 could be in that sentence) to increase CBF?

- maybe just a typo?

[CRNA2BKY]

Looks like a typo to me. I think they should've written PaO2 as you suggested.