This study investigates the effect of 4 different methods of rapid sequence induction (RSI) in morbidly obese patients on the amount of air insufflation into the stomach.
100 adult patients with a body mass index \> 40 undergoing elective laparoscopic surgery will be included. Patients with a history of previous bariatric surgery or with an anticipated difficult airway will be excluded. The randomization will be 1:1:1:1 stratified for gastro-esophageal reflux disease. All groups will receive standardized preoperative continuous positive airway pressure (CPAP) therapy. In the operation theater, Group one will receive pre-oxygenation for 3 minutes via a tight fitting face mask without positive end-expiratory pressure (PEEP). Induction agents will be administered as quick boluses (Propofol 2,5mg/kg total body weight, max 350mg, Fentanyl 250mcg, Rocuronium 1,2mg/kg ideal body weight) and tracheal intubation will be performed after 1 minute. No bag mask ventilation will be performed in-between. Group 2 will receive pre-oxygenation via a tight face mask with a PEEP of 10 mbar for 3 minutes. The same induction agents as in group one will be administered. PEEP via facemask will be continued for one minute and tracheal intubation will be performed. Group 3 will receive pre-oxygenation via a tight fitting facemask with a PEEP of 10 mbar with additional pressure support of 8 mbar and a back up ventilation frequency will be set to 10/min. After the same induction agents are given as in group 1, patients will receive non-invasive ventilation via ventilator at the settings described earlier for group 3. Group 4 will receive the same induction as group 3, in addition a cricoid pressure will be applied during the non invasive ventilation.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Preoxygenation via face mask, no ventilation with no PEEP until intubation
Preoxygenation via facemask with PEEP of 10 mbar. PEEP will be continued until intubation.
Preoxygenation via facemask with 10 mbar PEEP and 8 mbar pressure support. Backup frequency set at 10/min. Ventilation via anesthetic machine until intubation.
Medical University of Vienna
Vienna, Austria
Amount of air aspirated with a gastric tube
The amount of air that can be aspirated via a nasogastric tube at the beginning of laparoscopy. A nasogastric tube will be inserted at the beginning of laparoscopy and the air from the stomach will be aspirated with a syringe. The amount of air will be measured in ml.
Time frame: at the beginning of the laparoscopy
Gastric inflation
The impression of gastric inflation at laparoscopy. At the beginning of laparoscopy, images of the stomach will be recorded. These images will afterwards be reviewed in a blinded fashion by three different investigators. The investigators will rate their impression of gastric inflation (empty, mildly inflated, inflated, very inflated).
Time frame: at the beginning of laparoscopy
partial pressure of oxygen in arterial blood (paO2)
Arterial blood gases will we drawn at different time points to investigate oxygenation during the procedure. Blood gases will be taken before pre-oxygenation, before anesthesia induction, before laryngoscopy, after intubation.
Time frame: before pre oxygenation, before anesthesia induction, before laryngoscopy, immediately after intubation when the cuff of the tracheal tube is inflated
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Preoxygenation via facemask with 10 mbar PEEP and 8 mbar pressure support. Backup frequency set at 10/min. Ventilation via anesthetic machine until intubation.
Cricoid Pressure will be applied during RSI until laryngoscopy
Induction agents will be administered as quick boluses (Propofol 2,5mg/kg total body weight, max 350mg, Fentanyl 250mcg, Rocuronium 1,2mg/kg ideal body weight).
A nasogastric tube will be inserted at the beginning of laparoscopy and the air from the stomach will be aspirated with a syringe. The amount of air will be measured in ml.
The impression of gastric inflation at laparoscopy. At the beginning of laparoscopy, images of the stomach will be recorded.
Arterial blood gases will we drawn at different time points to investigate oxygenation during the procedure. Blood gases will be taken before pre-oxygenation, before anesthesia induction, before laryngoscopy, immediately after intubation when the cuff of the tracheal tube is inflated.