Laryngeal mask anesthesia

General anesthesia in patients undergoing diagnostic or therapeutic procedures.

1. Indications

  • General anesthesia of up to 90 – 120 minutes
  • Peripheral procedures
  • Ensuring oxygenation in exceptional cases, e.g., in difficult-to-intubate patients

2. Contraindications

  • Morbid obesity
  • Increased risk of aspiration (e.g., not fasting, GERD)
  • Lateral decubitus and prone procedures
  • Relative: Head and neck soft tissue procedures
  • Intraabdominal and thoracic surgery

 

 

3. Required

  • Detailed informed consent discussion
  • Physical examination and history
  • Possibly additional studies (e.g., lab panel, chest films, cardiological studies)
  • Patient informed consent

4. Workflow description

  • Device check by nurse anesthetist
  • Nursing staff premedicates patient at least 30 minutes before surgery is started, with midazolam oral syrup dosed as suggested below:

> 65 years: 0.1 mg/kg

≦ 65 years: 0.15 mg/kg

≦ 45 years: 0.2 mg/kg

 

Upon transfer of patient to nurse anesthetist:

  • Check name of patient
  • Check surgical field
  • Ask patient if fasting
  • Hook up standard monitoring leads/lines: ECG, NIBP, pulse oximetry
  • IV access and infusion
  • Document baseline measurements in anesthesia record
  • Prepare induction medication and materials needed for ventilation
  • Position patient on OR table
  • Anesthesiologist reviews the documents and checks them for completeness
  • Pre-oxygenate the patient with 100% oxygen via face mask
  • Administer opiate observing blood pressure and time to onset
  • Administer hypnotic until blink reflex lapses
  • Open mouth and check teeth
  • Once anesthesia is deep enough insert laryngeal mask
  • Check for possible leaks, ventilate and auscultate
  • Transport patient into OR
  • Hook up patient to ventilator in the OR
  • Check capnometry
  • Adjust flow, FiO2 and concentration of anesthetic gas
  • Hook up patient to the monitor units
  • Check patient position
  • Maintain patient's core body temperature
  • Administer medications to maintain anesthesia
  • Release patient to OR team
  • Prepare analgesia protocol

 

5. Intraoperative monitoring

  • Single-channel ECG
  • NIBP
  • Pulse oximetry
  • Capnometry
  • Check ventilation settings
  • Measure end-expiratory CO2 concentration
  • Measure inspiratory and expiratory anesthetic gas concentration
  • Measure inspiratory and expiratory oxygen concentration

6. Emergence

  • Check opiate overhang
  • Wash out anesthetic gas through high-flow setting
  • Restore patient's spontaneous breathing
  • Remove the laryngeal mask with blocked or unblocked cuff
  • Oral suction if needed
  • After removal of laryngeal mask observe respiration
  • Check vigilance

7. Hand over to recovery room

  • Hand over patient to nursing staff of recovery room
  • Check drains
  • Check vigilance
  • Hook up to monitor unit
  • Administer oxygen if needed
  • Obtain pain history and administer treatment
  • Anesthesiologist discharges patient from recovery room

8. Hints and notes

If after placing the laryngeal mask the level of anesthesia is not deep enough, the patient may develop hiccups which may not lapse despite deepening anesthesia, requiring a fast-acting relaxant for resolution

Unlike conventional laryngeal masks the Proseal® model allows ventilation with a peak pressure up to 25 mbar, permitting its use in obese patients. Since this dual-lumen mask also allows insertion of a gastric tube, it is possible to suction gastric juice in aspiration-prone patients.

Author: Prof.C. Diefenbach, MD Head, Department of Anesthesiology and Surgical Intensive Care

St. Katharinen-Hospital Frechen GmbH, Germany