Determination of insertion depth of flexible laryngeal mask airway in pediatric population-A prospective observational study.
OBJECTIVE
The purpose of this study was to determine the ideal insertion depth of the flexible laryngeal mask airway (FLMA) by elucidating the relationships between insertion depth and patient's age, body weight, height, and other parameters. We also evaluated an insertion technique that uses the change in intracuff pressure for proper positioning of the FLMA in cases where it is difficult to sense resistance during FLMA insertion.


METHODS
This study was a prospective observational study.


METHODS
Participants were recruited from the Seoul National University Children's Hospital.


METHODS
We enrolled 154 children aged ≤15 years with an American Society of Anesthesiologists physical status of I or II who were scheduled for ophthalmic surgery of <2 hours duration under general anesthesia.


METHODS
After induction of general anesthesia, FLMA insertion was guided by the change in intracuff pressure, measured using a manometer. The FLMA position was assessed using a fiberoptic bronchoscope.


METHODS
The FLMA insertion depth was measured at the end of each surgical procedure. A multiple linear regression model was then created using age, height, weight, nasal-tragus length, and sternal length.


RESULTS
The FLMA was successfully inserted in the first attempt in 134 patients using continuous monitoring of intracuff pressure. Using multiple linear regression analysis and the Durbin-Watson test, we found that insertion depth was best predicted by height and weight (r2=0.777), and the resulting formula was as follows: insertion depth of FLMA (cm)=7.0+0.04×height (cm)+0.05 ×weight (kg).


CONCLUSIONS
The FLMA insertion depth can be calculated using height and weight. Continuous monitoring of intracuff pressure during FLMA insertion is a useful alternative insertion method in cases where resistance is difficult to sense.
Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, #101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea.
Ji-Hyun
JH
Lee
Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, #101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea.
Hye-Won
HW
Oh
Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, #101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea.
In-Kyung
IK
Song
Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, #101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea.
Jin-Tae
JT
Kim
Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, #101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea.
Chong-Sung
CS
Kim
Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, #101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea. Electronic address: dami0605@snu.ac.kr.
Hee-Soo
HS
Kim
D000293:Adolescent; D000768:Anesthesia, General / Q000379:methods; D000886:Anthropometry / Q000379:methods; D001827:Body Height; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007442:Intubation, Intratracheal / Q000379:methods; D017214:Laryngeal Masks; D008297:Male; D008365:Manometry / Q000379:methods; D016343:Monitoring, Intraoperative / Q000379:methods; D011312:Pressure; D011446:Prospective Studies
Airway management; Anesthesia; Laryngeal mask airway; Pediatrics; Pressure; Technique