Pre-warming the Streamlined Liner of the Pharynx Airway (SLIPA) improves fitting to the laryngeal structure: a randomized, double-blind study

Abstract

Background: The Streamlined Liner of the Pharynx Airway (SLIPA), a type of supraglottic airway, has a non-inflatable cuff that softens at body temperature to fit the laryngeal structure. We investigated whether pre-warming of SLIPA to body temperature may improve insertion parameters.

Methods: Ninety adult patients were assigned equally randomized to either Group W or Group R. Anesthesia was induced using propofol, fentanyl, and rocuronium. In Group W, the SLIPA was warmed to 37 ° C before insertion, whereas in Group R, it was inserted at room temperature. The insertion time, oropharyngeal leak pressure, postoperative throat pain, blood staining, regurgitation, number of attempts at insertion, and difficulty of insertion were compared between the two groups.

Results: The insertion time was shorter in Group W than in Group R (3.60 [3.15-4.06] s vs. 6.00 [4.45-7.50] s; P < 0.001). Oropharyngeal leak pressure from the time of insertion until 3 min after insertion was significantly higher in Group W than in Group R (P < 0.05). Postoperative throat pain, measured using the visual analog scale, was lower in Group W than in Group R (0.00 [0.00-2.50] vs. 2.00 [0.00-4.50]; P = 0.006). The difficulty of insertion was lower in Group W than in Group R (P < 0.004). There were no significant differences in terms of blood staining, regurgitation, and number of attempts.

Conclusions: Pre-warming the SLIPA to body temperature has significant benefits compared to maintaining the device at room temperature. Specifically, insertion was easier, both insertion and fitting to the laryngeal structure could be performed more quickly, and the incidence of sore throat was reduced.

Trial registration: Clinical Research Information Identifier NCT01209000.

Figures

Fig. 1

CONSORT flow diagram. The progress of patients through the trial is shown. Group R: the Streamlined Liner of the Pharynx Airway (SLIPA) was kept at room temperature; Group W: the SLIPA was pre-warmed to 37 ° C

Fig. 2

Oropharyngeal leak pressure (OLP). OLP increased gradually over time in both groups. However, the mean OLP in Group W was significantly higher than that in Group R from the point of insertion until 3 min after insertion. Group R: the Streamlined Liner of the Pharynx Airway (SLIPA) was kept at room temperature; Group W: the SLIPA was pre-warmed to 37 ° C. Values are expressed as the mean ± SE. *P < 0.05

Fig. 3

Insertion time. The insertion time was faster in Group W (3.60 s [3.15–4.06 s]) than in Group R. Box-and-whisker plot (median, interquartile range, and range) of the insertion time in Group R and Group W. Group R: the Streamlined Liner of the Pharynx Airway (SLIPA) was kept at room temperature; Group W: the SLIPA was pre-warmed to 37 ° C. *P < 0.001

Fig. 4

Postoperative throat pain (visual analog scale [VAS]). Postoperative throat pain, determined using the VAS, was lower in Group W than in Group R. Box-and-whisker plot (median, interquartile range, and range) of the VAS in Group R and Group W. Group R: the Streamlined Liner of the Pharynx Airway (SLIPA) was kept at room temperature; Group W group: the SLIPA was pre-warmed to 37 ° C. *P = 0.006