The Effect Of Different Fraction Inspired Oxygen On Pulmonary Compliancy In The Prone Position During Posterior Spine Surgery

Objective:To investigate the effect of different fraction of inspired oxygen(FiO2) in the end of inspire on pulmonary compliancy in the prone position during posterior spine surgery.Methods:Sixty patients scheduled for posterior spine surgery were randomly allocated to receive mechanical ventilation using either FiO240%in the end of inspire(n=30, Group A) or FiO280%in the end of inspire(n=30, Group B). Respiratory variables [including peak airway pressure (Ppeak), dynamic compliance (Cdyn) and stationary compliance (Cstat)] and oxygenation parameters were recorded at the supine position5min after tracheal intubation(TO) and5min after prone positioning (T1),1h after prone positioning (T2),2h after prone positioning (T3)Results:(1) Peak airway pressure(Ppeak):During the study period, the Ppeak increased after prone positioning in both groups and the statistical significance existed at T1,T2, T3compared with TO (P<0.05or P<0.01). The increasing amplitude of Ppeak in Group A was lower than that in Group B.(2) Dynamic compliance(Cdyn): Cdyn decreased from supine position to prone position in both groups. The decreasing amplitude of Cdyn in the Group A was lower than that in Group B during the study period. There was statistical difference at T3compared with TO (P<0.05) in Group A, while T2and T3compared with TO in Group B(P<0.01).(3) Stationary compliance(Cstat):The Cstat decreased from supine position to prone position in both groups. The decreasing amplitude of Cdyn in the Group A was lower than that in Group B during the study period. There was statistical difference at T3compared with TO(P <0.05) in Group A and T2compared with TO (P<0.05) in Group B. There was significant statistical difference at T3compared with TO (P<0.01) in Group B. There were no statistical difference in pulmonary compliancy between the two groups at the same time(P>0.05).(4) Arterial partial pressure of oxygen(PaO2):PaO2in Group B was much higher than that in Group A [(298.1±51.0) mm Hg vs.(204.7±35.4)mm Hg, P<0.01].Conclusions:There was no statistical difference of pulmonary compliance between FiO2=40%and FiO2=80%in the end of inspire in patients who didn’t suffer from pulmonary disease undergoing posterior spine surgery in the prone position within2hours.