Influence of different head and neck positions on airway sealing pressure with i-gel laryngeal mask airway in patients undergoing elective surgery under general anesthesia with mechanical ventilation / 中华麻醉学杂志

ABSTRACT

Objective To investigate the influence of different head and neck positions on airway sealing pressure (OLP) with i-gel laryngeal mask airway (LMA) in patients undergoing elective surgery under general anesthesia with mechanical ventilation.Methods Thirty ASA Ⅰ or Ⅱ patients of both sexes aged 32-64 yr with a body mass index of 18-30 kg/m2 undergoing elective surgery under general anesthesia with LMA were studied.Size 4 i-gel LMA was placed blindly after induction of anesthesia and connected to anesthetic circuit.The criteria for successful placement were easy inflation with small leak,peak inspiratory pressure (PPeak) within normal range and normal PETCO2 wave form.Fiberoptic bronchoscopy was performed to check the position of LMA.OLP,expiratory tidal volume ( VTE ),PPeak and efficiency of mechanical ventilation were measured in different head and neck positions.OLP was measured by gradually increasing airway pressure until PPeak was reached.The measurement was stopped when there was large leak or OLP ＞ 35 cm H2 O.The efficacy of ventilation was evaluated by manually inflating the lungs (perfecteasy inflation,no audible leak; satisfactoryeasy inflation,small leak; poordifficult inflation,large leak).Results Flexion of the head significantly increased OLP and PPeak and decreased VTE,while hyperextension significantly decreased OLP and PPeak and increased VTE as compared with middle position of the head.Lung ventilation was less satisfactory when the head was flexed.Turning the head to either side did not affect ventilation.Conclusion Flexion of the head should be avoided when i-gel LMA is used during anesthesia.