Evaluation of the optimal cuff volume and cuff pressure of the revised laryngeal tube “LTS-D” in surgical patients

BACKGROUND: Recent case reports have indicated significant cuff overinflation when using the standard filling volume based on the manufacturer’s recommendations in older models of laryngeal tubes. The aim of this study was to determine the minimum cuff pressure needed to perform standardized ventilation without leakage in the new, revised model of the laryngeal tube “LTS-D”. METHODS: After ethical approval, LTS-D was placed for ventilation in 60 anesthetized patients. The cuff was inflated to the recommended volume (#3: 60 ml, #4: 80 ml, and #5: 90 ml). After evaluation of the initial cuff pressure (CP), the CP was lowered in 10 cmH(2)O steps until a minimal cuff pressure of 30 cmH(2)O was achieved. The absence of an audible leak was required for a step-by-step reduction in the CP. Evacuated cuff volume, success rate, and airway injuries were documented. Data were expressed as medians (interquartile ranges [IQRs]). The comparison of CPs and cuff volumes was performed using the Mann-Whitney test. RESULTS: After initial inflation, the CP ranged from 105 cmH(2)O [90–120; #5] to 120 cmH(2)O [110–120; #3]. Lowering the CP to 60 cmH(2)O resulted in a reduced cuff volume ranging from 47 ml [44–54; #3] to 77 ml [75–82; #5] compared to the initial inflation (p < 0.001). Leakage occurred more frequently when the CP was lowered to 40 cmH(2)O compared to the initial inflation (44/54 [81%]; p < 0.01). Using a CP between 50 cmH(2)O and 60 cmH(2)O, a leakage rate of 3/54 (5%) was observed, compared to a rate of 11/54 (21%) when using a CP lower than 50 cmH(2)O. The overall success rate was 90%, and airway injury occurred in 7% of patients (4/60). CONCLUSION: We found significant overinflation of the revised LTS-D using the recommended volume for initial cuff inflation. A CP of 60 cmH(2)O was found to be sufficient for ventilation in the majority of patients evaluated. Checking and adjusting the CP in laryngeal tubes is mandatory to avoid overinflation. TRIAL REGISTRATION: ClinicalTrials.gov NCT02300337. Registered: 20 November 2014. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12871-017-0308-4) contains supplementary material, which is available to authorized users.