Objective: To study the effects on cerebral dynamics and regional oxygenation (rSO2) of the semi-sitting position, with the head at either 30 degrees or 45 degrees, in surgery for cerebral hemorrhage.
Patients and methods: We performed a prospective study of 10 patients undergoing surgery for cerebral hemorrhage under sedation and analgesia and with mechanical ventilation. Intracranial pressure (ICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), and rSO2 measured using near-infrared spectroscopy were recorded with the head in the supine position (0 degrees) and elevated to an angle of 30 degrees and then 45 degrees, following a stabilization period of 5 minutes.
Results: Mean (SD) ICP values were significantly lower in both semi-sitting positions than in the supine position: 2.8 (1.4) mm Hg lower at 30 degrees and 4.4 (1.4) mm Hg lower at 45 degrees. Mean CPP values were fell slightly when the head was elevated to 30 degrees (3.5 [3.1] mm Hg, P=.048); a greater reduction was achieved when the head was elevated 45 degrees (7.1 [4.8] mm Hg, P<.01). The greatest reduction in mean MAP values also occurred with the head elevated to 45 degrees (11.8 [4.6] mm Hg, P<.001). Mean rSO2 values fell when the head was elevated to 30 degrees and 45 degrees; the greatest reduction occurred when the head was elevated to 45 degrees (7% [2%], P<.001). There was a moderate correlation between CPP values and changes in rSO2 (r2=0.45, P<.001).
Conclusion: Head elevation significantly reduces ICP and CPP in patients with cerebral hemorrhage. Head elevation also reduces rSO2, to a greater or lesser extent depending on the degree to which the head is elevated.