A Comparison of the Blind Intubation and the Fiberscope-guided Intubation Techniques via Laryngeal Mask Airway / 대한마취과학회지

BACKGROUND: The laryngeal mask airway (LMA) has an established role in difficult airway management as a ventilatory device and airway intubator. It is ease to view the laryngeal aperature with a fiberscope through a laryngeal mask airway, so it offers a route to obtaining rapid access to the larynx. The objective of this study was to evaluate a narrowing degree of LMA by the epiglottis and to compare the intubation time and success rate of the blind intubation techinique with the fiberscope-guided intubation techinique through the laryngeal mask airway. METHODS: The LMA (#4) was placed into the hypopharynx after induction of anesthesia and muscle paralysis. The fiberscopic findings through the lumen of the LMA were recorded after the LMA placements. The degree of narrowing of the LMA by the epiglottis was estimated as 0%, 1 25%, 26 50%, 51 75%, or 76 100%. The breathing circuit of the anesthesia circle system was then disconnected from the LMA and a well-lubricated, cuffed, 5.5 mm ID endotracheal tube was inserted into the trachea through the lumen of the LMA either by the blind techiniques or fiberscope-guided techniques, and then intubation time and success rate were measured. RESULTS: The most frequent incidence (44/60, 73.3%) of narrowing by epiglottis in both groups was 76 100%. The success rate for fiberscope-guided intubation was 100%, while the success rate for blind intubation was 20%. The average intubation time of fiberscope-guided intubation was 26.0 s, while the average intubation time of blind intubation was 17.7 s. CONCLUSIONS: The fiberscope-guided tracheal intubation technique through the LMA is a more reliable method than the blind intubation technique through the LMA.

A Comparison of the Blind Intubation and the Fiberscope-guided Intubation Techniques via Laryngeal Mask Airway / 대한마취과학회지

BACKGROUND: The laryngeal mask airway (LMA) has an established role in difficult airway management as a ventilatory device and airway intubator. It is ease to view the laryngeal aperature with a fiberscope through a laryngeal mask airway, so it offers a route to obtaining rapid access to the larynx. The objective of this study was to evaluate a narrowing degree of LMA by the epiglottis and to compare the intubation time and success rate of the blind intubation techinique with the fiberscope-guided intubation techinique through the laryngeal mask airway. METHODS: The LMA (#4) was placed into the hypopharynx after induction of anesthesia and muscle paralysis. The fiberscopic findings through the lumen of the LMA were recorded after the LMA placements. The degree of narrowing of the LMA by the epiglottis was estimated as 0%, 1 25%, 26 50%, 51 75%, or 76 100%. The breathing circuit of the anesthesia circle system was then disconnected from the LMA and a well-lubricated, cuffed, 5.5 mm ID endotracheal tube was inserted into the trachea through the lumen of the LMA either by the blind techiniques or fiberscope-guided techniques, and then intubation time and success rate were measured. RESULTS: The most frequent incidence (44/60, 73.3%) of narrowing by epiglottis in both groups was 76 100%. The success rate for fiberscope-guided intubation was 100%, while the success rate for blind intubation was 20%. The average intubation time of fiberscope-guided intubation was 26.0 s, while the average intubation time of blind intubation was 17.7 s. CONCLUSIONS: The fiberscope-guided tracheal intubation technique through the LMA is a more reliable method than the blind intubation technique through the LMA.

Assessment of Positive Pressure Controlled Ventilation with the Laryngeal Mask Airway / 대한구급학회지

BACKGOUND: Cuff overinflation may cause premature rejection of the laryngeal mask airway (LMA) or provocation of incomplete and ineffective reflex responses. Therefore a previous report recommends that the cuff is inflated to a pressure of 60 cmH2O to minimize side effects. The objective of this study was to assess the possibility of controlled positive pressure ventilation in adults when intra-cuff pressure of LMA was set to 60 cmH2O. METHODS: We studied 20 adult patients who received general inhalational anesthesia with LMA and mechanical positive pressure ventilation for gynecological operations. The following variables was determined during anesthesia at two time points 3 min after endotracheal intubation and 5 min before neuromuscular blockade: pop-off pressure, tidal volume, peak-air way pressure, plateau pressure, compliance, SpO2, and ETCO2. RESULTS: Mean compliances measured were normal. Mean airway pressures (peak, plateau) were 13.6 and 15.1 cmH2O at two time points respectively while setting the tidal volume with 10 ml/kg. However, pop-off pressure were 18.3 and 20.1 cmH2O, respectively. Mean tidal volumes without gas leak around the LMA cuff were 14.5 and 14.5 ml/kg, respectively. Mean SpO2 and mean ETCO2 were measured 99.0 and 99.2%, 31.3 and 30.3 mmHg in two time points, respectively. CONCLUSIONS: The study suggested that controlled mechanical positive pressure ventilation using the laryngeal mask airway with 60 cmH2O intra-cuff pressure were be adequate when pulmonary compliance and airway resistance were normal.