Effect of different types of laryngeal mask airway placement on the right internal jugular vein: A prospective randomized controlled trial

Table 1 Baseline demographics and characteristics

	Group 1, n = 32	Group 2, n = 39	Group 3, n = 29	P value
Gender, Male/Female	2/30	6/33	5/24	0.342
Age in yr	50 ± 16	49 ± 15	49 ± 16	0.932
Height in cm	163 ± 5	164 ± 6	163 ± 7	0.626
BMI in kg/m2	23 ± 3	23 ± 3	23 ± 3	0.754
ASA, I/II	17/15	26/13	18/11	0.503
LMA size, 3/4/5	4/27/1	3/35/1	5/23/1	0.807

ASA: The American Society of Anesthesiologists; BMI: Body mass index; LMA: Laryngeal mask airway.

Table 2 Overlap index

	Group 1, n = 32	Group 2, n = 39	Group 3, n = 29	P value
High point
Before LMA	21.7 (6.5, 61.5)	23.4 (0, 51.6)	25.7 (12.2, 60.2)	0.712
After LMA	100 (100, 100)d	72.1 (40.0, 100)ad	100 (69.0, 100)ad	0.000
Middle point
Before LMA	52.8 (29.1, 82.7)	44.8 (18.5, 65.9)	40.3 (19.6, 100)	0.624
After LMA	100 (100, 100)d	100 (100, 100)d	100 (100, 100)d	0.318
Low point
Before LMA	26.2 (0.0, 97.8)	41.0 (11.5, 94.5)	30.3 (0, 100)	0.465
After LMA	67.8 (18.5, 100)d	56.3 (12.1, 100)	54.7 (22.5, 100)d	0.993

^aP < 0.05 vs group 1;

^dP < 0.01 vs before laryngeal mask airway within group. Results are presented as median (interquartile range). LMA: Laryngeal mask airway.

Table 3 Relationship between simulated needle path and internal jugular vein and common carotid artery, n (%)

	Group 1, n = 32	Group 2, n = 39	Group 3, n = 29	P value
IJV
Before LMA	31 (96.9)	38 (97.4)	24 (82.8)	0.059
After LMA	24 (75.0)d	31 (79.5)ad	15 (51.7)d	0.036
CCA
Before LMA	6 (18.8)	8 (20.5)	7 (24.1)	0.871
After LMA	19 (59.4)d	17 (43.6)d	13 (44.8)	0.361
IJV and CCA
Before LMA	6 (18.8)	7 (17.9)	3 (10.3)	0.613
After LMA	17 (53.1)d	16 (41.0)d	9 (31.0)	0.215

^aP < 0.05 vs group 3;

^dP < 0.01 vs before laryngeal mask airway within group. IJV: Internal jugular vein; CCA: Common carotid artery; LMA: Laryngeal mask airway.

Table 4 Cross-sectional area and blood flow velocity of the internal jugular vein

	Group 1, n = 30	Group 2, n = 39	Group 3, n = 29	P value1
Cross sectional area in cm2
Before LMA2	1.42 ± 0.48	1.66 ± 0.68	1.54 ± 0.66	0.350
After LMA	1.62 ± 0.56	1.82 ± 0.77	1.66 ± 0.65
Flow velocity in cm/s
Before LMA3	31.25 ± 7.37	28.37 ± 8.49	31.82 ± 12.55	0.511
After LMA	24.07 ± 8.99	24.65 ± 8.55	26.45 ± 10.55

¹Compared between groups;

²Before LMA vs After LMA: P = 0.001;

³Before LMA vs After LMA: P = 0.000. Results are presented as the mean ± SD. LMA: Laryngeal mask airway.