We read with interest the article by Este-McDonald et al1 and were impressed by the conclusive results. However, we have some comments on the accompanying discussion by John Shillito, Jr, MD. Dr Shillito states that absorption of intraperitoneal CO2 may increase Pco2 which, in turn, may produce a further increase in cerebral edema.1 Certainly, it is well known that increased Pco2 increases cerebral blood flow and volume, and increased Pco2 also increases the rate of cerebrospinal fluid formation to normal values if it was decreased at normocapnia. Increase of cerebral blood volume or cerebrospinal fluid volume may elevate intracranial pressure. However, it is not certain that increased Pco2 increases cerebral edema. For example, Evans et al2 reported that in fetal sheep increased Pco2 caused increased brain uptake of sucrose labeled with carbon 14 and decreased brain
Shapira Y, Artru AA, Lam AM. Changes in Intracranial Pressure Associated With Apneumic Retractors. Arch Surg. 1996;131(10):1116. doi:10.1001/archsurg.1996.01430220110030
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