To investigate the effect of propofol intra-aortic and intravenous infusion on the concentration of propofol for an ischemia-reperfusion spinal cord injury in rabbits. Methods Forty-six healthy adult New Zealand white rabbits were randomly divided into 3 groups: sal ine infusion group (group N, n=10), propofol intra-aortic infusion group (group A, n=16) and propofol intravenous infusion group (group V, n=16). The infrarenal abdominal aorta was occluded for 30 min during which propofol 50 mg/kg was infused continuously intra-aortic or intravenous with a pump in group A and V. In group N, the same volume of normal sal ine was infused in the same way and at the same rate as in group A. Upon reperfusion, propofol concentration of the spinal segments of L4-6 and T6-8 was examined in group A and V. At 48 hoursafter reperfusion, the neurological outcomes were recorded in each group. Results Mean blood pressure in group V from the time of 5 minutes after occlusion decreased more than in group N (P lt; 0.05) and than in group A from the time of 10 minutes after occlusion(P lt; 0.05). The mean blood pressure in group N increased more than in group A from 15 minutes after occlusion (P lt; 0.05). The heart rate increased more in group V from 10 minutes after occlusion than in group N and A (P lt; 0.05) in which no difference was observed. The propofol concentration in L4-6 of group A (26 950.5 ± 30 242.3) ng/g was higher than that in T6-8 of group A (3 587.4 ± 2 479.3) ng/g and both L4-6 (3 045.9 ± 2 252.9) ng/g and T6-8 (3 181.1 ± 1 720.9) ng/g of group V(P lt; 0.05). The paraplegia incidence was lower (30%) and the median of normal neurons was higher (8.4) in group A than in group N (80%, 2.2) and group V(100%, 1.9), (P lt; 0.05). There was no significant difference in group N and V in paraplegia incidenceand the median of normal neurons (P gt; 0.05). Conclusion Intra-aortic infusion shows a better neurological outcome than intravenous infusion and could contribute to higher concentration of propofol in the ischemia spinal cord.
Objective To investigate the curve correlation between ventilation pressure and tidal volume in assisted mechanical ventilation with facemask during anesthesia induction. Methods Between January and August 2015, 120 patients, American Society of Anesthesiology Ⅰ-Ⅱ, undergoing selective gynecological surgery were randomly divided into four groups: groups P5, P10, P15 and P20, with 30 patients in each group. Mask ventilation pressure for the four groups were respectively 5, 10, 15 and 20 cm H2O (1 cm H2O=0.098 kPa). Patients were ventilated by preset ventilation pressure and frequency based on different groups after loss of consciousness. Mean ventilation volume (mean value of three tidal volumes) and end-tidal carbon dioxide pressure (PetCO2) were recorded for analysis. Results There was no significant difference among the four groups in patient’s general condition (P>0.05). The tidal volume of assisted mechanical ventilation increased with ventilation pressure degrees, and the differences among the four groups were significant (P<0.05). After curve regression analysis, tidal volume and ventilation pressure showed a positive linear correlation when ventilation pressure was set at 5-20 cm H2O, and the correlation equation was: tidal volume = 33.612×ventilation pressure-53.155. PetCO2 in P5 group was lower than those in the other three groups (P<0.05), while there were no significant differences among groups P10, P15 and P20 (P>0.05). Conclusion When ventilation pressure is set at 5-20 cm H2O in assisted mechanical ventilation with facemask during anesthesia induction, tidal volume and ventilation pressure show a positive linear correlation.