Investigate The Variation Of Cuff Volume And Intracuff Pressure In Different Position

Objective: To explore the intracuff pressure(ICP)of a laryngeal maskairway (LMA) with different cuff volume both in the prone position and in thesupine position.Method：forty (male24，female16) ASA I or II patients, aged22to67,weighing50~70kg, BMI<30kg/m2，scheduled for elective lumbar surgery, wereincluded in the study. General anesthesia was induced and then a size4deflatedLMA was inserted. Measured the intracuff pressure of LMA inflated with5~30ml (on the increase of5m1) of air both in supine (group A) and prone(group B) position and then recorded the corresponded actual tidal volume(Vat). Nausea&vomiting, choking, aspiration, hypoxemia and the extent ofblood around the laryngeal mask were noted, alongside with sore throat,hoarseness, difficulty swallowing within24hours after surgery.Result：Inflated with the same volume of air, both airway peak pressureand ICP in group A were lower than those in group B (P<0.05). When cuffvolume was15~25ml, ICP was23.5±3.1~46.3±4.5cmH2O and actual tidalvolume of92.5~100%patients reached90%set tidal volume in supine position;when cuff volume was30ml, ICP was64.5±5.5cmH2O and more thanrecommended60cmH2O in supine position. When cuff volume was15~20ml, ICP was31.8±3.7~50.2±3.0cmH2O and actual tidal volume of95~100%patients reached90%set tidal volume in prone position; when cuff volume was25ml, ICP was67.0±6.6cmH2O and more than recommended60cmH2O inprone position. During removing the LMA, all patients had no nausea andvomiting, choking, and aspiration, there was one case of hypoxia and two caseswith blood staining on the LMA after its removal; all patients were nodysphonia and dysphagia and one case of postoperative sore throat pain24hours after operation.Conclusion: the cuff volume is significantly reduced in prone position,the intracuff volume is obviously higher in prone position than that in supineposition with the same cuff volume. It is needed to select the most appropriatecuff volume in the clinical work according to the actual position.