Preschool children have specific anatomical and physiological characteristics which necessitates careful selection of an appropriate airway management device. Supraglottic airway devices can be used in anticipated or unanticipated difficult airway providing continuous oxygenation and ventilation with less hemodynamic stress response and less postoperative complications. So alternative techniques such as SADs have gained prominence in pediatric anesthesia both as primary airway and as a conduit for endotracheal intubation. So this study will evaluate the clinical performance of Laryseal Clear and Ambu Aura40 laryngeal mask airway in preschool children undergoing surgical procedures.

This study will be conducted in the operating theaters of department of anesthesia, intensive Care and pain management in Zagazig University hospitals within 12 months.

Sample size:

Assuming the mean difference of oropharyngeal leak pressure is 24.83±10.52 cm H2O for Ambu Aura40 group and 18.1±5.1 cm H2O for laryseal clear group (SF Bell et al., 2012) (KP Kaur et al.,2024), so the sample size was calculated to be 48 (24 in each group) sample size was calculated using open epi at confidence interval 95% & power 80%. To compensate for the possible drop out the sample size will be increased by 10%.

Study population:

Selected patients will be divided into 2 groups:

• Group L (LarySeal clear Group): The laryseal laryngeal mask will be used as a primary airway management device during the surgical procedure.
• Group A (Ambu Aura40 Group): The Ambu Aura40 Laryngeal Mask will be used as a primary airway management device during the surgical procedure.

The device size selection and insertion procedure will follow the manufacturer's guidelines.

Withdrawal Criteria: Patient's parents or guardians of the first degree have the right to withdraw from the study at any time without any negative consequences on their medical or surgical treatment plan, Failed 3rd attempt of SGAD insertion and need for endotracheal intubation.

Randomization:

All patients will be randomized using computer generated randomization table into 2 equal groups and will be allocated either in Laryseal clear group (group L) or Ambu Aura40 group (group A).

Randomization assignments will be kept in sealed envelopes until the day of surgery, and then they will be opened by the research anesthesiologist immediately prior to the operation.

Operational design:

Preoperative preparation:

All patients will be subjected to:

1. Detailed history taking including personal history, present history of the disease, family history of previous anesthetic complications and history of previous surgery with difficult airway management or any anesthetic complications.

2. Fasting before the operation: 8 hours for solids and 2 hours for free fluids.

3. Complete general and physical examination including thorough airway examination.

4. Laboratory investigations including complete blood picture, liver and kidney functions and coagulation profile.

   Intraoperative management:

   Upon arrival in the operating room, standard monitoring will be applied, including: Electrocardiography (ECG), Pulse oximetry (SpO2), Noninvasive blood pressure (NIBP), Capnogram (ETCO2) after securing the SGAD, Baseline measurement of heart rate, respiratory rate, SpO2 and blood pressure.

   The children will receive premedication 30 minutes before induction of general anesthesia in the form of intramuscular midazolam 0.07 mg/kg and intramuscular atropine 0.02 mg/kg.

   Inhalation induction will be done using sevoflurane up to 8% in 100% oxygen. When the child is asleep, an intravenous line will be secured with appropriate gauge cannula.

5. After securing intravenous access, fentanyl 1 µg/kg and rocuronium 0.6mg/kg will be administered then mask ventilation will be performed for 3 minutes with sevoflurane with MAC(2-8%) to ensure adequate anesthetic depth and muscle relaxation.

   When an appropriate depth of anesthesia and muscle relaxation is achieved (absence of motor response to jaw thrust), insertion of the SGAD will be attempted.

6. Selection of the LMA size will be based on the body weight of the patient (Bennett et al., 1996). The device will be lubricated by a water-based jelly before placement.

7. Group L (LarySeal clear Group): Patient's airway will be secured with the LarySeal laryngeal mask.

   • The head of the patient will be placed in the dorsiflexion sniffing position and a lubricated LMA of appropriate size (LarySeal, Flexicare medical Ltd., UK) will be inserted using the index finger digital method technique according to manufacturers guideline.

8. Group A (Ambu Aura40 Group): Patient's airway will be secured with the Ambu Aura40 laryngeal mask.

   • Patient's head will be in neutral position, a lubricated Ambu® Aura40(Ambu A/S, Copenhagen, Denmark) of appropriate size will be inserted using the non rotational midline approach according to manufacturer's guideline.
   • To ensure optimal inflation of SGAD cuff, it will be inflated with a volume of air according to the manufacturer's guidance (7 ml for size 1.5, 10 ml for size 2, 14 ml for size 2.5, and 20 ml for size 3).

9. Correct placement of the device will be confirmed by square wave capnography, adequate chest movement, easy bag ventilation, auscultation of bilateral air entry, and oxygen saturation greater than or equal to 95%.

10. If the ventilation is inadequate, manipulation will be done to adjust the device position in the form of pushing or pulling the device, head extension or flexion, and jaw thrust or chin lift, and the number of manipulations done will be recorded.

11. Failed insertion attempt is defined as an inability to insert the device or provide sufficient ventilation despite three airway manipulations.

12. A maximum of 3 insertion attempt will be allowed after which, the patient's airway will be secured by an endotracheal tube, and the patient will be withdrawn from the study.

13. Anesthesia will be maintained with 1-2 % of sevoflurane with 100% oxygen. Controlled ventilation will be performed with a tidal volume of 8-10 ml/kg and respiratory rate will be adjusted to keep the end-tidal carbon dioxide (EtCO2) between 35 and 40 mmHg.

14. After the surgical procedure, sevoflurane will be discontinued; atropine 0.01 mg/kg and neostigmine 0.05 mg/kg will be administered to antagonize the residual neuromuscular block.

15. The device will be removed when the child is fully awake evidenced by spontaneous eye opening, facial grimacing, and signs of adequate motor activity such as reaching for the device and adequate respiratory pattern.

16. Complications related to SGAD will be recorded during recovery, such as coughing, laryngospasm, airway obstruction, hypoxia (SpO2<92%), suspicion of regurgitation (presence of gastric fluid in the ventilation tube), blood staining on the removed device, and any lip, tongue, or dental trauma.

17. The patient will be transferred to the PACU to observed by a blinded investigator for any complications related to the SAD such as dysphonia, dysphagia, cough, or stridor.

18. All SGADs insertions will be performed by an anesthesiologist with experience in supraglottic airway devices insertions in clinical practice.

Inclusion Criteria:

• Consent of patient's parents or guardians of the first degree.
• American Society of Anesthesiologists (ASA) Class I or II.
• BMI: 5-85% of the children of the same age and sex.
• Patients with mallampati grade I, II
• Type of anesthesia: general anesthesia expected to last for less than 2 hours.

Exclusion Criteria:

• Emergency surgeries.
• Expected difficult airway.
• Patients with congenital or acquired airway malformations.
• Patients with active upper respiratory tract infection at the time of surgery.
• Patients with history of gastroesophageal reflux disease (GERD).
• Patients with neuromuscular disorders affecting airway tone or respiratory function.