Prospective study to compare two different technique of Proseal LMA placement.

This is a prospective randomized control trial. Adult consenting ASA 1 and 11 patients (Age 18-80 years) who are planned to receive an LMA for airway management for their surgery under general anaesthesia will be included.

A standard anesthesia protocol for LMA insertion practiced at TMC will be followed and routine monitoring applied (continuous ECG,ETC02,non invasive blood pressure and oxygen saturation monitoring) Patients will administered oxygen for 3 min. Induction of anesthesia was with Fentanyl 2–4 mg/kg and Propofol 2.5–4.0 mg/kg given over 30 s.

Once the jaw is relaxed the mouth will be opened and the PLMA inserted by an anaesthetist well trained in LMA insertion (more than 2 years of anaesthesia training and > 50 LMA insertions) Patients will be randomly allocated to either standard insertion technique using the metal introducer tool (IT) or the novel technique using the plastic stylet (ST) instead of the introducer to preshape the LMA  (determined by opening an opaque sealed envelope)

The IT technique involves attaching the IT,using a single-handed rotational tech-nique to press the PLMA into, and advance it around, the palatopharyngeal curve, and then removing the IT. The ST technique involves introducing the stylet through the drain tube upto the tip of the PLMA and then preshaping the PLMA using the stylet. Insertion technique is similar to that of the IT technique, After placement the stylet will be removed.

The size of proseal LMA used will be as recommended the manufacturer

Weight

PLMA size

|30-50

3

|50-70

4

|70-100

5

 Both techniques will be performed with the cuff fully deflated and using a midline approach. Once the PLMA was inserted into the pharynx, the cuff was inflated with air using the maximum recommended inflation volume. Time taken for the PLMA insertion will be noted. (Time for opening the mouth to completion of LMA insertion (removal of stylet/introducer tool) When insertion will is successful, intracuff pressure will set at 60 cm H2O using cuff pressure monitor and PLMA will be fixed with tube tape. Patients lungs will be ventilated at an inspired tidal volume of 8- 10 mL/kg, a respiratory rate of 12/min and an inspiratory:expiratory ratio of 1:2.

The presence/absence of oropharyngeal air leaks  (detected by listening over the mouth ), gastric air leaks (detected by listening with a stethoscope over the epigastrium ), drain tube air leaks (detected by placing lubricant over the proximal end of the drain tube), or an end-tidal CO2 >45 mm Hg will noted. A well-lubricated 60-cm long, 12-Fr gastric tube was inserted through the drain if there is no air leak up the drain tube. Correct gastric tube placement is assessed by suction of fluid or detection of injected air by epigastric stethoscopy.

Three attempts were allowed before insertion was considered a failure. Failed insertion was defined by any of the following criteria: 1) failed passage into the pharynx; 2) malposition (air leaks or failed gastric tube insertion if pharyngeal placement successful) and 3)ineffective ventilation (maximum expired tidal volume < 8 mL/kg or end-tidal CO2 > 45 mm Hg if correctly positioned).

Once PLMA placement is successful as judged by clinical parameter ,a fiberscope will be quickly inserted through the PLMA (through the ventilating tube) and the placement of the PLMA will be graded (less than 30 seconds) as per Brimacombe classification(Grade I-IV) .This will tell us the exact position of the LMA.

The airway position was scored from the mask aperture bars by using the system proposed by Brimacombe and Berry.

4 = only vocal cords visible;

3 = vocal cords plus posterior epiglottis visible;

2 = vocal cords plus anterior epiglottis visible;

1 = vocal cords not fiberoptically visible;

0 = failure to insert or to function.

Cardiorespiratory data were collected (every minute) for 5 minutes before and after PLMA insertion. Any episodes of bradycardia (HR <40/min), tachycardia >100/min, or systolic hypotension (SBP < 80 mm Hg,hypertension SBP > 160 mm Hg) will be documented,  any episodes of hypoxia (Spo2< 90%) or other adverse events will be noted. Any visible trauma during insertion will be noted. Visible blood staining on the stylet , IT, or PLMA was noted at removal.

Data about failed passage into the pharynx, insertion time, and the etiology of failure were collected by an unblinded observer. Data about malposition, effective ventilation, hypoxic episodes, and blood staining will be collected by an observer blinded to the insertion technique.