Abstract
BackgroundRecent 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”.MethodsAfter 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 cmH2O steps until a minimal cuff pressure of 30 cmH2O 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.ResultsAfter initial inflation, the CP ranged from 105 cmH2O [90–120; #5] to 120 cmH2O [110–120; #3]. Lowering the CP to 60 cmH2O 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 cmH2O compared to the initial inflation (44/54 [81%]; p < 0.01). Using a CP between 50 cmH2O and 60 cmH2O, a leakage rate of 3/54 (5%) was observed, compared to a rate of 11/54 (21%) when using a CP lower than 50 cmH2O. The overall success rate was 90%, and airway injury occurred in 7% of patients (4/60).ConclusionWe found significant overinflation of the revised LTS-D using the recommended volume for initial cuff inflation. A CP of 60 cmH2O 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 registrationClinicalTrials.gov NCT02300337. Registered: 20 November 2014.
Highlights
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
Demographics From December 2014 to February 2015, 60 (33 female, 27 male) adult patients undergoing general anesthesia for ophthalmic surgery were included in this trial (Fig. 3)
Using an uncontrolled cuff pressure (CP), ventilation was possible in every patient without detectable leakage (Table 3)
Summary
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”. Compared to the previous version of the LTS-D, which has a 45° curvature of the tube, the revised model has a 60° curvature, producing a more angulated tube that allows easier insertion into the pharynx. The ventilation part of the revised LTS-D is slimmer compared to the previous version. Several studies have reported complications associated with the previous versions of LT, such as a sore throat and blood traces on the cuff [5-7|. Several authors have shown reduced pharyngeal mucosal microcirculation when the CP exceeds > 35 cmH2O [8,9,10,11]
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