Effect of controlled hypercapnia on cerebrospinal fluid pressure and operating conditions during transsphenoidal operations for pituitary macroadenoma

Abstract

Controlled hypercapnia was assessed for its effectiveness in raising cerebrospinal fluid pressure to enable descent of the suprasellar portion of pituitary macroadenomas during transsphenoidal surgery. The result was compared in a randomized, single blind trial with intermittent boluses of saline injected intrathecally. Intrathecal pressures were monitored in both groups. Twenty-seven of 29 patients in the study group and 25 of 28 patients in the control group reached the target pressure of 20 mm Hg. The mean ETCO2 at the time of maximum pressure was 42.34 +/- 4.75 mm Hg in the study group and 29.81 +/- 2.61 mm Hg in the control group, (P< .001). Mean arterial carbon dioxide was 46.90 +/- 6.55 and 31.42 +/- 4.87 mm Hg, respectively. Surgeons blinded to the technique assessed the descent of the tumor. The operating conditions were judged by the surgeons to be satisfactory for 20 patients in the study group and 17 patients in the control group. Both techniques were equally effective in raising intracranial pressure and in providing descent of the suprasellar component of the tumor. No untoward side effects occurred while using either technique. The authors conclude that controlled hypercapnia is effective in producing descent of the suprasellar portion of a pituitary adenoma.