Effect Of Different Head Positions On Cerebral Oxygen Saturation During Spinal Surgery In Elderly Patients

Objective:To investigate the effect of different head positions on regional cerebral oxygen saturation（r SO₂）in elderly patients with spinal surgery.Methods:There were 60 elderly patients included in elective general anesthesia for thoracolumbar spine surgery,and were divided into O group,L group and R group by random number method,with 20 cases each.Among them,Group O remains in a neutral position after switching to a prone position,Group L deflects its head to the left（no more than 45°）after switching to a prone position,and Group R tilts its head to the right（no more than 45°）after switching to a prone position.Bilateral local cerebral oxygen saturation（r SO₂）,mean arterial pressure（MAP）,heart rate（HR）,pulse oxygen saturation（Sp O₂）,and post-call carbon dioxide（Pet CO₂）were recorded for before inhalation of pure oxygen（T₀）,after endotracheal intubation（T₁）,5min before prone position（T₂）,5min after prone position（T₃）,30min after prone position（T₄）,60min after prone position（T₅）,90min after prone position（T₆）,2h after prone position（T₇）.The minimum value of r SO₂in surgery(r SO_2min)and the maximum difference between r SO₂and the maximum decrease of r SO₂from baseline(Δr SO_2max)were calculated based on the mean value of r SO₂at T₂as the baseline value.At the same time,the arterial hematological blood gas analysis of patients at various time points was collected to measure the hemoglobin concentration（Hb）and blood lactate content（Lac）.Results:There were no significant differences in the values of MAP,HR,Sp O₂and Pet CO₂at the time points before and after the prone position of the three groups（P>0.05）.After switching to the prone position,Lac showed an elevated trend in the three groups,and T₆and T₇were significantly higher than T_2。After the patient switched to prone position,the r SO₂values on the left and right sides of each observation time point were lower than the T₂level,and the r SO₂values in the three groups of T₅to T₇decreased significantly compared with T₂（P<0.05）.There was no statistically significant difference in the comparison of the baseline values of the three sets of r SO₂（P>0.05）.Compared with L group and R group,r SO_2minin O group was significantly increased,andΔr SO_2maxwas significantly reduced（P<0.05）.Conclusion:In elderly patients,maintaining a neutral position of the head in prone position has the least impact on r SO₂,so the head is kept in a neutral position when performing spinal surgery in the prone position to maintain the balance of cerebral oxygen.