Optimal Head Rotation and External Landmark for Internal Jugular Vein Cannulation After Placement of Proseal Laryngeal Mask Airway
Condition: General Anesthesia With Laryngeal Mask Airway (LMA)
Study type: Observational

Summary: 
      Recently, laryngeal mask airway (LMA) placements are frequently performed for general
      anesthesia. The investigators occasionally encounter a clinical situation to perform internal
      jugular vein (IJV) cannulation after LMA insertion, especially for difficult airway in
      subjects undergoing major surgery. However, anatomic relations of IJV and common carotid
      artery (CCA) in patient with LMA placement have been reported to be different from those in
      patients with endotracheal tube. The degree of overlapping of the right IJV and CCA after LMA
      placement was greater than before LMA placement. Furthermore, there are many cases of
      complete overlapping right IJV and CCA after LMA placement. Therefore, the risk of puncturing
      CCA increases when the investigators try to cannulate IJV after LMA placement. Furthermore,
      the central landmark commonly used for IJV cannulation was proved to show low success rate
      after LMA placement in previous report.

      The investigators carefully examined the anatomic relations of IJV and CCA after LMA
      insertion with ultrasonography, and found that the degree of overlapping is different
      according to the degree of head rotation. The investigators postulated that if the degree of
      overlapping is different according to the degree of head rotation after LMA insertion, the
      investigators can find the angle of head rotation for least overlapping and reduce the risk
      of CCA puncture. Therefore, the investigators tried (1) to find the optimal head rotation
      angle appropriate for puncturing IJV after LMA placement, and (2) to find suitable landmark
      adequate for IJV cannulation after LMA placement.
    

Detailed description: 
      Recently, laryngeal mask airway (LMA) placements are frequently performed for general
      anesthesia. The investigators occasionally encounter a clinical situation to perform internal
      jugular vein (IJV) cannulation after LMA insertion, especially for difficult airway in
      subjects undergoing major surgery. However, anatomic relations of IJV and common carotid
      artery (CCA) in patient with LMA placement have been reported to be different from those in
      patients with endotracheal tube. The degree of overlapping of the right IJV and CCA after LMA
      placement was greater than before LMA placement. Furthermore, there are many cases of
      complete overlapping right IJV and CCA after LMA placement. Therefore, the risk of puncturing
      CCA increases when the investigators try to cannulate IJV after LMA placement. Furthermore,
      the central landmark commonly used for IJV cannulation was proved to show low success rate
      after LMA placement in previous report. Previous study recommended the lower puncture point
      near that area where the clavicular head of the sternocleidomastoid muscle attaches to the
      clavicle, because CCA was not observed in the vicinity of the IJV after LMA insertion. Even
      though they performed test puncture at the lower puncture point in 20 patients and found no
      complications, the lower puncture point is not the usual site for IJV cannulation for most
      anesthesiologists. It is known that increased head rotation is associated with high
      probability of CCA contact. The investigators carefully examined the anatomic relations of
      IJV and CCA after LMA insertion with ultrasonography, and found that the degree of
      overlapping is different according to the degree of head rotation. The investigators
      postulated that if the degree of overlapping is different according to the degree of head
      rotation after LMA insertion, the investigators can find the angle of head rotation for least
      overlapping and reduce the risk of CCA puncture. Therefore, the investigators tried (1) to
      find the optimal head rotation angle appropriate for puncturing IJV after LMA placement, and
      (2) to find suitable landmark adequate for IJV cannulation after LMA placement.
    

Intervention name(s): Head rotation
Intervention type(s): Other
Intervention description(s): Repeated ultrasonographic examination according to the degree of head rotation (examination of overlap index of internal jugular vein and common carotid artery, and accuracy of external landmark of jugular cannulation)
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        patients undergoing general anesthesia with laryngeal mask airway insertion
      
Keywords: Laryngeal mask airway; internal jugular vein cannulation