Effect Of Prone Position On Oxygenation And Intra-abdominal Pressure With Different BMI Using Jackson Table

Intra-abdominal pressure and oxygenation index are associated with body mass index when patients are in the supine position.The effect of body mass index on oxygenation has been rarely reported in the prone position,especially on Jackson surgical table.In the prone position,the change of oxygenation is correlated to the increased of functional residual capacity,the improved of ventilation/perfusion ratio,if there is any other factors remain uncertain.It was reported that,intra-abdominal pressure for pigs with normal lung function between 12mmHg-20mmHg,the effect of intra-abdominal pressure on the oxygenation was very small,for pigs with acute lung injury,oxygenation index will gradually declined with increased intra-abdominal pressure.Obese patients'intra-abdominal pressure is between 9mmHg-15mm Hg,which is higher than patients of normal weight.In the prone position,chest and abdomen was compressed,whether the intra-abdominal pressure will be further increased and the relationship between intra-abdominal pressure and oxygenation index will be affected or not were rarely reported in obese patients using Jackson surgery table.ObjectivesTo explore the effect of body mass index on respiratory function and oxygenation while patients using Jackson surgical table or general surgical table in the prone position.To explore the effect of posture on intra-abdominal pressure while using the two different surgical tables,so to provide reference for prevent perioperative lung injury and hypoxemia.MethodsThis study was divided into two parts of experiment:in the first part,ASA graded?-?level,56 patients undergoing lumber surgery were randomly allocated to two groups,Jackson group and Normal group,and then subgroup was divided according to body mass index,General group?BMI:18.5-24.9kg/m²?and Overweight group?BMI:>25kg/m²?,general group was divided into two groups using Jackson surgical table named group GJ and using Normal table named group GN,likewise,Overweight group was divided into two groups using Jackson surgical table named group OJ and using Normal table named group ON.Each group was 14 cases.Peak inspiratory pressure?PIP?and inspiratory plateau pressure?Pplat?were recorded in the supine position after induction of anesthesia,in the prone position for 10min,in the prone position at the end of surgery,in the supine position at the end of surgery.Oxygenation index?OI?and dynamic lung compliance(C_dyn)were recorded in the supine position after induction of anesthesia,in the prone position for 10min,in the prone position for 30min,in the prone position for 1h.Volume control mechanical ventilation mode was used,without PEEP.In the second part,like the first part mentioned,Intra-abdominal pressure and central venous pressure were recorded at the time of point.Volume control mechanical ventilation mode was used,without PEEP.ResultsIn the first part,after patients changed from supine position to prone position:oxygenation significantly improved while using Jackson operating table?P<0.01?,and compared to normal table,oxygenation improved significantly while overweight patients prone for 1h?P<0.05?.There was no significant difference among group GJ about C_dyn?P>0.05?,while there was statistically significant difference in group OJ and group N?P<0.05?.Compared to Jackson table,C_dyn decreased significantly in overweight patients?P<0.05?.The airway pressure increased significantly except group GJ?P<0.05?,and the airway pressure was significantly higher in the group ON than that in the group OJ while prone for 10min?P<0.05?.In the second part,IAP decreased in the prone position for 10min in both group GN and group ON?P<0.05?,also decreased in both group GJ and group OJ?P<0.01?.IAP decreased more in group OJ than in group ON?P<0.01?.CVP increased in the prone position while using normal table?P<0.05?,and CVP decreased in the prone position using Jackson table?P<0.01?.In the prone position,there was correlation between IAP and BMI,OI and BMI,PIP and C_dyn,P_platlat and IAP in Jackson group?P<0.01?,r respectively presented as 0.4712,-0.6803,-0.6991,0.6987,in normal group except the correlation between P_platlat and IAP?P<0.05?,r respectively presented as 0.8775,-0.4463,-0.8314.Univariate analysis of variance showed that intercept between the two surgical table about the above mentioned correlation was significant difference?P<0.01?.There was positive correlation between IAP and CVP in Jackson group?P<0.01?,r was 0.7093.ConclusionIn the prone position,Jackson surgical table prior to normal surgical table,as follows:IAP decreased more obviously,there was a positive correlation between IAP and Pplat,C_dyn decreased slightly,and oxygenation improved more obviously,so it has advantage for obese,poorly cardiopulmonary function patients who need to be prone position for a long time.In the prone position,when BMI increased the IAP increased,but the OI decreased,and compared to normal table,IAP was lower and OI was higher corresponding to the same of BMI.The operating Jackson table can not only effectively improve oxygenation,but also can effectively reduce the IAP.Above all,placing patients reasonable,suspending abdomen,it is useful for preoperative management of respiratory function and reduce preoperative lung injury for obese patients.Using Jackson table,there was a significant correlation between IAP and CVP in the prone position,monitoring IAP could reflect CVP indirectly,to provide reference for fluid administration in the prone position.