Gas leak and gastric insufflation during controlled ventilation: face maskversus laryngeal mask airway

Abstract

R~.TPurpose: To compare two airway management techniques, face mask (FM) with oropharyngeal airway and laryngeal mask airway (LMA), with respect to the effectiveness of positive pressure ventilation and airway maintenance. Methods: After induction of anaesthesia, two airway management techniques (FM or LMA) and three peak pressures (20, 25 and 30 cm H20 ) were randomly applied during controlled ventilation in 60 patients. Data collected included inspiratory and expiratory volumes and presence of gastro-oesophageal ins~ation. Leak was calculated by subtracting the expiratory from the inspiratory volume, expressed as a fraction of the inspiratory volume. Results: Expiratory volumes (mean _+ SD) at 20, 25 and 30 cm H20 for LMA ventilation were 893 _+ 260, 986 -+ 276 and 1006 +_ 262 respectively, and for FM ventilation 964 + 264, I 100 + 268 and I 116 + 261. Leak fractions at 20, 25 and 30 cm H20 for LMA ventilation were 0.21 + 0.15, 0.24 _+ 0.18 and 0.26 -+ 0.18 respectively, and for FM ventilation 0.14 _+ 0.09, 0.14 _+ 0.09 and 0. 12 _+ 0.08. The frequency of gastro-oesophageal insuft]ation was 1.6%, 5% and 5% for the LMA and 5%, 15% and 26.6% for the FM for ventilation pressures of 20, 25 and 30 cm H20 respectively which was greater with LMA use. Conclusion: Ventilation was adequate in all patients using both techniques. Leak was pressure dependent and greater with LMA use. Most of the leak was vented to the atmosphere via the pharynx. Gastro-oesophage~ insufflation was more frequent with ventilation using the face mask. LMA use with positive pressure ventilation would appear to be a better airway management method than the face mask. Conclusion : La ventilation a 6t6 ad6quate chez tousles patients en utilisant l'une ou rautre technique. La fuite &air plus grande avec le ML, d6pendait de la pression et &alt en grande pattie 6vacu6e dans ratmosph&e par le pharynx. l'insufl]ation gastro-oesophagienne Etait plus frEquente avec I'utilisation du ME ILutilisation du ML Iors de ventilation pression positive semble une meilleure m~thode de maintien des voies a&iennes que I'utilisation du masque facial.

The LMA-ProSeal™ is an effective alternative to tracheal intubation for laparoscopic cholecystectomy

“…Independent laparoscopic assessment of stomach size by our General Surgery colleagues, who were blinded to the airway device being used, enabled us to avoid the use of surrogate auditory markers to detect gas leakage into the stomach. 11,12 Increase in stomach size in this study never interfered with surgical exposure. This was also the finding in our previous study of the LMA-C and ETT, when none of the 53 patients in the LMA-C group required gastric decompression.…”

Gastric distension and ventilation during laparoscopic cholecystectomy: LMA-classic vs. tracheal intubation

“…4 However, neither these studies nor those in which the LMA was used during laparoscopic cholecystectomy 4,7 measured gastric distension or oropharyngeal leak. Investigators who used surrogate markers to detect air entry into the stomach [8][9][10][11] exceeded the manufacturer's recommended range for tidal volumes and airway pressures. 1 2 One group acknowledged that the qualitative, not quantitative, method to detect gastroesophageal insufflation was the weak point of their study.…”

LMA-Classic™ and LMA-ProSeal™ are effective alternatives to endotracheal intubation for gynecologic laparoscopy

“…In the present study, laparoscopic assessment of stomach size by our gynecologist colleagues, who were blinded to the airway device being used, enabled us to avoid the use of surrogate auditory markers to detect gas leakage into the stomach. 23,24 In no patient did change in stomach size interfere with the surgical field.…”