The Influence of Head and Neck Position About Oropharyngeal Leak Pressure and Sealing Between the Laryngeal Mask and Vocal Cord Using Different Types of Supraglottic Airway Device
Condition: the Influence of Oropharyngeal Leak Pressure and Sealing Between the Mask and Vocal Cord During Changing Patient's Head and Neck Position
Study type: Interventional
Phase: Phase 1/Phase 2

Summary: 
      Generally, the laryngeal mask airway is not considered in the surgery which should be
      changing position in the perioperative period. The shape of the pharynx changes during the
      head and neck movement and there is probably also a change in the force transmitted to the
      cuff along the airway tube. Besides, there is evidence that supraglottic airway device can be
      displaced with rotation. In this article, the investigators want to discuss about that
      oropharyngeal leak pressure and sealing between the mask and vocal cord while changing head
      and neck position in perioperative period using different types of supraglottic airway
      device.
    

Detailed description: 
      The investigators select adult patients,who are 20-80yrs old and ASA physical status I or II,
      receiving minor surgery, ex: breast surgery or cystoscope, participated in this randomized
      cross-over trial. Patients were excluded if they were in the above condition. The patient is
      at high risk of aspiration, ex:obesity, pregnancy upper GI bleeding or not enough fasting
      time. The patient could not open mouth or upper airway obstruction. The patient receive major
      surgery, ex: heart, brain, lung, liver, kidney surgery. The patient has abnormal heart and
      lung function.

      The patient received different types of supraglottic airway device like proseal LMA,ambu LMA,
      air Q LMA or igel LMA by draw, then the patients will be divided into different groups.In the
      preoperative period, the investigators documented oropharyngeal leak pressure in these
      selected positions: neutral position( 0 degree),and rotation 15, 30,45, 60 degrees, etc.
      However, oropharyngeal leak pressure was measured by closing the expiratory valve of the
      circle system at fixed O2 flow 3L/min and 20 cm H2O. If the ambu bag is flattening, the
      investigators will think the leakage happened between the laryngeal mask and our vocal cord.
      Then the investigators use fiberscope to observe the condition between the epiglottis and the
      laryngeal mask.

      The investigators wanted to compared the mean leak pressure at different head and neck
      rotation position,ex:neutral,30,45,60 degrees,by using many different types of supraglottic
      airway device.

      The observers define the relationship between epiglottis and vocal cord to describe the
      condition when the patient is at different degree of head and neck position. Grade I is vocal
      cord completely visible. Grade IIA is only partially vocal cord visible and epiglottis noted.
      Grade IIB is no vocal cord visible and only epiglottis noted. Grade III is other condition,
      ex:trapped epiglottis or no epiglottis visible.
    

Intervention name(s): LMA proseal; igel LMA; air Q LMA; ambu LMA
Intervention type(s): Device; Device; Device; Device
Intervention description(s): It would be used to observe the leak pressure at 30,45,60 degree of the head and neck position and the condition between the vocal cord and peri-laryngeal region. The cuff pressure would be kept at 30 cm H20.; It would be used to observe the leak pressure at 30,45,60 degree of the head and neck position and the condition between the vocal cord and peri-laryngeal region.; It would be used to observe the leak pressure at 30,45,60 degree of the head and neck position and the condition between the vocal cord and peri-laryngeal region. The cuff pressure would be kept at 30 cm H20.; It would be used to observe the leak pressure at 30,45,60 degree of the head and neck position and the condition between the vocal cord and peri-laryngeal region. The cuff pressure would be kept at 30 cm H20.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: supraglottic airway,igel-LMA, ambu-LMA, changing position, head and neck position, oropharyngeal leak pressure,degree of rotation