Office Based Total Intravenous General Anesthesia with Laryngeal Mask Airway: Pump vs. Bump Technique
Office Based Total Intravenous General Anesthesia with Laryngeal Mask Airway: Pump vs. Bump Technique
Saturday, September 15, 2012: 8:00 AM
Statement of the Problem: There are many ways to perform office based general anesthesia, but the ability to control the patient’s airway remains critical to patient safety. In the past, use of an LMA has been used with inhalation anesthetics and a ventilator. A ventilator is costly and may not be available in every practitioner’s office. Also, malignant hyperthermia (MH) becomes a risk when using inhalation anesthetics or succinylcholine. We compare two techniques that may be used in-office for total IV GA with an LMA.
Materials and Methods: 20 cases were retrospectively reviewed, 10 cases using the manual bump injection technique and 10 cases using the automated pump technique. Cases were performed using an LMA with IV agents midazolam, propofol and remifentanil. All cases were performed on patients with ASA 1 or 2, and with Malampatti scores 1, 2 or 3. Patients were pre-oxygenated with nasal canula oxygen at 3 L/minute. 4 to 5 mg of midazolam was used to pre-medicate before induction. Patients were then subsequently induced with a mixture of propofol:remifentanil (10mg:3 mcg per mL) and the induction dose was 1 to 2 mg/kg (dosing was based on the propofol concentration). Following adequate induction, an LMA size 3 or 4 was inserted with standard insertion technique. The patient was then ventilated with an ambu bag with oxygen delivered at 10 liters/minute connected to the LMA until spontaneous ventilation began.
Bump Technique: Anesthesia was sustained by using a mixture of propofol:remifentanil at 10 mg:5 mcg per mL. This was used in an IV push or “bump” method. 1 to 3 mL was administered intermittently in order to maintain adequate anesthesia and adjusted based on patient response.
Pump Technique: Anesthesia was sustained by using a mixture of propofol:remifentanil at 10 mg:5 mcg per mL on a Baxter infusion pump at an infusion rate of 0.15 mg/kg/min:0.075 mcg/kg/min and rate was adjusted during the procedure based on patient response.
For both techniques the ambu bag with oxygen being delivered maintained connected to the LMA throughout procedure to allow oxygen at a rate of 8 liters/minute.
Methods of Data Analysis: Subjective analysis of 20 cases regarding anesthetic and post anesthetic complications. The two techniques were then objectively compared using 3 parameters. 1) Average amount of anesthetic used 2) Average length of procedure 3) Cost effectiveness per technique. Cost effectiveness was determined by analyzing the average amount of anesthetic used per kg/minute.
Results of Investigation:
Average Length of Procedure: 44.29 minutes for Pump and 32.5 minutes for Bump
Average amount of propofol:remifentanil per procedure: 437.14mg:177.71mcg for Pump and 237mg:92.6mcg for Bump.
Average amount of propofol:remifentanil per kg/minute: 0.16mg/kg/min:0.07mcg/kg/min for Pump and 0.13mg/kg/min:0.05mcg/kg/min for Bump.
Incidence of laryngospasm was 5%, there were no occurrences of chest rigidity, significant bradycardia, hypotension necessitating treatment or insufflation of the stomach resulting in vomiting.
Conclusion: Use of the LMA provides the advantages of a more protected airway with fewer desaturations. Toleration of the LMA did not require an inhalational anesthetic, yet maintained spontaneous ventilation while providing the patient with adequate anesthesia for the procedure. The bump technique proved more cost effective by not requiring the use of a pump, using 46% less propofol and 48% less remifentanil and using 15% less mg/kg/minute of propofol and 22% less mg/kg/minute of remifentanil. Both techniques eliminate the use of a ventilator and inhalational anesthetic which provides significant cost savings and decrease risks.
References:
Bennett, et al. Use of the laryngeal mask airway in oral and maxillofacial surgery. J Oral Maxillofac Surg. 1996;54:1346
Todd DW. The laryngeal mask airway for general anesthesia: the case for its use. J Oral Maxillofac Surg. 2004;62(6):736-738
Materials and Methods: 20 cases were retrospectively reviewed, 10 cases using the manual bump injection technique and 10 cases using the automated pump technique. Cases were performed using an LMA with IV agents midazolam, propofol and remifentanil. All cases were performed on patients with ASA 1 or 2, and with Malampatti scores 1, 2 or 3. Patients were pre-oxygenated with nasal canula oxygen at 3 L/minute. 4 to 5 mg of midazolam was used to pre-medicate before induction. Patients were then subsequently induced with a mixture of propofol:remifentanil (10mg:3 mcg per mL) and the induction dose was 1 to 2 mg/kg (dosing was based on the propofol concentration). Following adequate induction, an LMA size 3 or 4 was inserted with standard insertion technique. The patient was then ventilated with an ambu bag with oxygen delivered at 10 liters/minute connected to the LMA until spontaneous ventilation began.
Bump Technique: Anesthesia was sustained by using a mixture of propofol:remifentanil at 10 mg:5 mcg per mL. This was used in an IV push or “bump” method. 1 to 3 mL was administered intermittently in order to maintain adequate anesthesia and adjusted based on patient response.
Pump Technique: Anesthesia was sustained by using a mixture of propofol:remifentanil at 10 mg:5 mcg per mL on a Baxter infusion pump at an infusion rate of 0.15 mg/kg/min:0.075 mcg/kg/min and rate was adjusted during the procedure based on patient response.
For both techniques the ambu bag with oxygen being delivered maintained connected to the LMA throughout procedure to allow oxygen at a rate of 8 liters/minute.
Methods of Data Analysis: Subjective analysis of 20 cases regarding anesthetic and post anesthetic complications. The two techniques were then objectively compared using 3 parameters. 1) Average amount of anesthetic used 2) Average length of procedure 3) Cost effectiveness per technique. Cost effectiveness was determined by analyzing the average amount of anesthetic used per kg/minute.
Results of Investigation:
Average Length of Procedure: 44.29 minutes for Pump and 32.5 minutes for Bump
Average amount of propofol:remifentanil per procedure: 437.14mg:177.71mcg for Pump and 237mg:92.6mcg for Bump.
Average amount of propofol:remifentanil per kg/minute: 0.16mg/kg/min:0.07mcg/kg/min for Pump and 0.13mg/kg/min:0.05mcg/kg/min for Bump.
Incidence of laryngospasm was 5%, there were no occurrences of chest rigidity, significant bradycardia, hypotension necessitating treatment or insufflation of the stomach resulting in vomiting.
Conclusion: Use of the LMA provides the advantages of a more protected airway with fewer desaturations. Toleration of the LMA did not require an inhalational anesthetic, yet maintained spontaneous ventilation while providing the patient with adequate anesthesia for the procedure. The bump technique proved more cost effective by not requiring the use of a pump, using 46% less propofol and 48% less remifentanil and using 15% less mg/kg/minute of propofol and 22% less mg/kg/minute of remifentanil. Both techniques eliminate the use of a ventilator and inhalational anesthetic which provides significant cost savings and decrease risks.
References:
Bennett, et al. Use of the laryngeal mask airway in oral and maxillofacial surgery. J Oral Maxillofac Surg. 1996;54:1346
Todd DW. The laryngeal mask airway for general anesthesia: the case for its use. J Oral Maxillofac Surg. 2004;62(6):736-738