Laryngeal Mask Supreme During Laparoscopic Gynecologic Surgery

This prospective, randomized and double-blind study received permission from "Dokuz Eylül University Medical Faculty Non-Interventional Research Ethics Committee" and after obtaining patients' informed consent, 100 patients with American society of anesthesiologists (ASA) classification group I-II, between 18-65 years, undergoing elective laparoscopic gynecological surgery were included.

Patients were divided into:

Group 1=>ETT (50 patients) Group 2=>LM-S (50 patients) Patients and surgeons performing the operation were not aware of which airway device was used. The patients in the groups were determined by block randomized methods.

Patients taken to the surgical room were given standard monitoring (non-invasive blood pressure measurements, electrocardiogram, and peripheral oxygen saturation measurements) before anesthesia induction. For preoperative sedation 0.02 mg/kg midazolam IV was administered.

Patients were preoxygenated with 6 L/min oxygen for 3 minutes through a face mask.

For anesthesia induction after 2 minutes of 0.2 µg/kg/min remifentanil and 6 mg/kg/hr propofol infusion, IV 1-2 mg/kg propofol was administered. After induction patients were ventilated with 6 L/min 100% fraction of inspired oxygen inspired oxygen fraction oxygen through a face mask. Anesthesia depth was standardized in all patients using bispectral index monitoring. Bispectral index values were held between 40-60. Bispectral index values were maintained in this interval by increasing or decreasing propofol infusion by 1 mg/kg.

Airway devices were inserted by two researchers with more than 5 years experience.

During airway device placement according to patient reactions an extra dose of 0.5 mg/kg propofol was given if necessary.

Anesthetic maintenance was provided by 50% O2/air mixture with 0.1-0.4 µg/kg/min remifentanil and 50-150 µg/kg/hr (3-9 mg/kg/hr) propofol IV infusion.

Before LM-S was inserted, to lubricate the surface in contact with the palate a water-based gel without local anesthetic was applied to completely cover the LM-S cuff. Depending on the patient's body weight For <50 kg, no. 3 Between 50-70 kg, no. 4 Between 70-100 kg, no. 5 LM-S (The Laryngeal Mask Company Limited, Singapore) was inserted.

After LM-S placement the cuff was inflated with air so as to have a pressure below 60 centimeters of water (cuff pressure manometer, Rusch, Germany). Two minutes after LM-S placement, before insufflation, 10 minutes after insufflation and trendelenburg position, before desufflation and before LM-S removal, cuff pressure was measured repeatedly and recorded. At the same time intervals in the ETT group, ETT cuff pressure was measured.

In the ETT group for women no. 7-7.5 tube was used. The ETT cuff was inflated until the leak sound ceased. It was measured with a manometer to remain between 20-30 centimeters of water.

Successful placement of LM or ETT was confirmed by square-shaped waves observed on the capnogram, easy ventilation of the respiration balloon and visible chest movements. After successful placement of the airway device, it was covered to prevent observation of which device was used.

The length of time for successful placement (duration from mouth opening to first successful ventilation), number of tries, and ease of placement were recorded. Ease of placement was evaluated by the anesthetist in charge of the airway as easy, hard or unsuccessful (alternative airway management).

In a situation where airway provision was unsuccessful after 3 tries, patients without placement of LM-S or who could not be intubated were switched to the other group and airway management was provided.

For oropharyngeal leak test after the expiratory valve was closed air was shut off, O2 was reduced to 3 L/min and the first pressure value when a leak sound was heard was recorded as the oropharyngeal leak pressure. To prevent exposure of the lungs to barotrauma, when the peak inspiratory pressure reached 40centimeters of water the expiratory valve was opened and the test was concluded. This test was repeated before peritoneal insufflation, 10 minutes later and immediately before desufflation and was completed by a researcher blind to the type of airway device inserted.

Positive pressure respiration was begun by using a ring system, 2-4 L/min fresh gas flow and 0.5 volume controlled 6-8 ml/kg tidal volume and 10 respirations/min frequency. Positive end expiratory pressure was not administered and I:E ratio was adjusted to 1:2. ETCO2 was held between 35-45 mmHg, if necessary first respiration frequency was increased then tidal volume was increased. Permission was given for CO2 insufflation for the laparoscopic intervention with peritoneal interior pressure of 15 mmHg.

Two minutes after LM-S or ETT placement, before insufflation, 10 minutes after insufflation and trendelenburg position, immediately before peritoneal desufflation and before airway device removal, ventilation parameters were evaluated.

Respiratory measurements to be recorded: Tidal volume (TV), respiration number (RN), peripheral oxygen saturation (SPO2), end-tidal carbon dioxide pressure (PETCO2), peak airway pressure (P peak), mean airway pressure (P mean) and expiration volume per minute (VE).

Hemodynamic measurements to be recorded: (simultaneous to the measurements above and additionally before induction) Systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP) and heart rate (HR).

Evaluation related to gastric tube:

Immediately after airway device placement using either the LM-S drainage tube or in intubated patients using a 14 F orogastric probe within the airway, the stomach was reached and the gastric contents were aspirated. Ease of placement and amount of fluids aspirated were recorded. Ease of placement was classified by the person who inserted the orogastric probe as very easy, easy, difficult and very difficult.

The number of interventions with Verres needle, initial intra-abdominal pressure, duration to reach intra-abdominal pressure of 15 mmHg, and insufflated volume of CO2 were recorded. Sufficiency of pneumoperitoneum (sufficient/insufficient), and quality of airway provision were evaluated by the surgeon who was blind to the airway device used by giving points between 1-4.

Immediately after the intra-abdominal laparoscopic intervention and immediately before peritoneal insufflation was ended, gastric distension was evaluated by a surgeon blind to the airway device used between 0-10 (0=empty stomach, 10=distension obstructing the surgical field) and the difference between the scores at the start and end of the operation was recorded.

When the patient cooperated LM-S or ETT was removed and total anesthesia duration and peritoneal insufflation duration was recorded. Possible complications that could develop during airway device removal (coughing, vomiting, laryngeal stridor, laryngeal spasm or requirement for airway intervention) were recorded.

After laryngeal supra glottic airway device removal the presence of blood was evaluated as

1. no blood
2. trace amounts of blood
3. clear amount of blood Revived patients were taken to the recovery unit and a blind researcher evaluated the patients' throat pain, hoarseness and presence of difficulty swallowing in the 1st and 24th hours. To evaluate throat pain the visual analogue scale was used.