Comparison of Gastric Insufflation Volume Between LarySeal Pro and Ambu AuraGain Using Ultrasonography In Pediatric Patients Undergoing General Anesthesia With Controlled Ventilation.

Comparison of Gastric Insufflation Volume Between LarySeal Pro and Ambu AuraGain Using Ultrasonography In Pediatric Patients Undergoing General Anesthesia With Controlled Ventilation. A Randomized Controlled Trial.

Gastric air insufflation during insertion of a laryngeal mask airway (LMA) is a known phenomenon and can have important clinical implications, especially in relation to: During positive pressure ventilation or improper insertion technique, air can be forced into the esophagus and stomach or LMAs do not fully seal the esophagus, so high ventilation pressures or incorrect placement may lead to gastric insufflation. Which may lead to Increased risk of regurgitation and aspiration, especially if the gastric contents reach the upper esophagus, Abdominal distension, which can reduce ventilation efficiency, nausea, vomiting, or delayed gastric emptying postoperatively which detected by Epigastric auscultation may reveal gurgling sounds during ventilation, Gastric ultrasound can visualize the extent of gastric insufflation and Capnography sometimes shows altered patterns if regurgitation begins . This complication prevented by:

• Use low-pressure, controlled ventilation (<20 cmH₂O).
• Ensure proper size and positioning of the LMA.
• Use second-generation LMAs (like LarySealPro or Ambu AuraGain LMA) that have gastric drainage ports to relieve air.

Consider gastric ultrasound preoperatively to assess risk . (1)

Several studies have assessed the performance of Ambu AuraGain and LarySeal Pro individually or in comparison with other supraglottic airway devices. Ambu AuraGain, a second-generation device with a gastric drainage channel, has demonstrated high oropharyngeal leak pressures and ease of insertion, making it suitable for positive pressure ventilation. LarySeal Pro has also shown favorable results in terms of low airway resistance and effective sealing in adults. However, direct comparisons between these two devices are limited, especially regarding gastric insufflation volume measured by ultrasonography, which offers objective and quantitative assessment. Although some adult studies have evaluated AuraGain against devices like ProSeal or i-gel, there is a notable lack of pediatric studies directly comparing AuraGain and LarySeal Pro using gastric ultrasound techniques.(2) To date, no published randomized controlled trials have directly compared gastric insufflation volumes between Ambu AuraGain and LarySeal Pro using ultrasonography in pediatric patients under general anesthesia. This represents a critical gap in the literature, given the increased risk of aspiration in children and the growing use of ultrasound to evaluate perioperative gastric content.

Compared to Endotracheal intubation , SADs offer reported advantages such as simplicity in insertion, elimination of neuromuscular blocking agents, enhancement of spontaneous respiration, and avoidance of translaryngeal positioning accompanied by cardiovascular effects and close vocal cord contact. reduced rate of laryngospasm and a lower incidence of postoperative hoarse voice, coughing and sore throat. (3)

Despite this, the use of these device may be associated with various complications as regurgitation and aspiration of gastric contents, compression of vascular structures, trauma, and nerve injury.(4). The LMA can be a useful airway device in pediatric patients as well as adults, despite clear differences between the anatomy of the pediatric and adult airway. Sizes I, 2, and 2 1/2 are available for use in infants and children. In general, children require greater anesthetic depth prior to placement . The LMA can be placed successfully in children after either an inhalational or intravenous induction of anesthesia. (5) Ambu AuraGain and LarySeal Pro are designed with a cuff modified to improve the seal around the glottis and a drainage tube to provide a bypass channel for regurgitated gastric contents, prevent gastric insufflation, and allow the passage of a gastric tube. These features are designed to improve the safety of the mask and broaden its scope, especially when used with positive pressure ventilation.(6) Aim of the work The aim of the study is to compare the gastric insufflation volume between the LarySeal Pro Laryngeal Mask and Ambu AuraGain Laryngeal Mask in pediatric patients undergoing general anesthesia with controlled ventilation.

Objectives:

To assess and compare gastric insufflation volume between LarySeal Pro laryngeal mask and Ambu AuraGain laryngeal mask in pediatric patients using pelviabdominal ultrasound undergoing general anesthesia.

Hypothesis We hypothesize that LarySeal Pro laryngeal mask produce gastric insufflation volume less than Ambu AuraGain laryngeal mask in pediatric patients undergoing general anesthesia.

I. Study design Randomized Controlled Clinical Trial II. Study setting and location The location of where the study will be conducted (Pediatric Specialized Hospital, Cairo University) III. Study population This section should describe the target population, including patients who are between 2-10 years old undergoing general anesthesia with controlled ventilation.

IV. Eligibility Criteria

1. Inclusion criteria

   • Age: pediatrics (2-10 years )
   • Patients with a Mallampati score of I - II
   • Elective surgeries
   • Short procedure expected to last for 1 hour or less .
   • ASA I - II

2. Exclusion criteria • Age: below 2 years and above 12 years

   • Patient with airway masses
   • Active upper respiratory tract infections, pneumonia, COPD & exacerbated bronchial asthma.
   • Patient with gastroesophgeal reflux ( hiatus hernia , achalasia )
   • Patient with abnormal airway anatomy
   • Coagulation disorders.
   • Patients with any cardiac conditions (IHD, RHD, decompensated heart failure and arrhythmia).

V. Study Procedures

1. Randomization

   Randomization will be done by computer generated numbers and concealed by serially numbered, opaque and sealed envelopes. The details of the series will be unknown to the investigators and the group assignment will be kept in asset of sealed envelopes each bearing only the case number on the outside, and divided into 2 equal groups:

   Group A in which LarySeal Pro will be used for ventilation. Group B in which Ambu AuraGain will be used for ventilation.

2. Study Protocol

1. Pre-operative : On the day before surgery, patients will undergo a through pre-anesthetic check-up, including routine preoperative investigations. They will be instructed to fast before surgery. (Table 1) Intake Type Minimum Fasting Duration Clear liquids 2 hours Breast milk 4 hours Infant formula 6 hours Non-human milk 6 hours Solid food (light meal) 6 hours Fatty or heavy meal 8 hours Table 1: Pre-operative fasting hours in pediatric patients. (7)

After being accepted into the study according to inclusion criteria, the patients were admitted into the pre-operative room and Routine monitoring devices were connected to the patients (Electrocardiography, noninvasive blood pressure, pulse oximetry for O2 saturation ), proper airway assessment of the patients will be done.

2. Intra operative : Before induction of anesthesia, a gastric antrum ultrasound will be performed to assess gastric air volume by measuring the cross-sectional area of the gastric antrum in a supine position. (Fig 1.) This will be done using a portable sonographic system (GE/Vivid T8/1.3-4 MHz) with a curved array transducer, and anatomical landmarks will be used to identify the gastric antrum which will be in the sagittal to right parasagittal plane using the left lobe of the liver, the pancreas, abdominal aorta or inferior vena cava. Important vascular landmarks including the aorta, inferior vena cava (IVC) and either the superior mesenteric artery or vein will be used to standardize a scanning plane through the antrum. The measurements will be taken between antral contractions to provide an accurate baseline value.

Figure 1: gastric antral cross-sectional area (CSA) in the supine position.(8)

In operation room, routine monitoring is established before induction of anesthesia (Electrocardiography, noninvasive blood pressure, pulse oximetry for O2 saturation) and all patient recieved Midazolam 0.05mg/kg for anxiety .

Patients will be randomly allocated to one of two groups. Either Group A, receiving the LarySeal Pro laryngeal mask and Group B, receiving the Ambu Aura laryngeal mask.

Induction of general anesthesia will be achieved by inhalation induction by sevoflurane then securing IV access by proper sized cannula then all patients will received Fentanyl 1ug/kg, Propofol 2mg/kg and,tracium 0.5mg/kg. Ventilation will be carried out using manual mask ventilation ( by < 15 cmH2O ) conducting oxygen 100% , 2 minimum alveolar concentration of Sevoflurane and intravenous fluids are started .

Mechanical ventilation will be employed with the following parameters: tidal volume (Vt) set between 6-8 milliliters per kilogram of ideal body weight, respiratory rate maintained at 14-16 breaths per minute to achieve an end-tidal carbon dioxide (EtCO2) concentration of 35-40 mmHg. An inspiratory to expiratory ratio (I: E) of 1:2 will be used, and the peak airway pressure (pmax) will be kept below <15 centimeters of water (cmH2O) to avoid gastric insufflation (air entering the stomach & reduce aspiration risk . The proper size of the device is selected according to manufacturer's recommendations. Proper positioning will be confirmed by inspection of chest inflation bilaterally, auscultation of the chest bilaterally, auscultation of the neck for abnormal respiratory sounds, absence of any leak sounds from the device, adequate tidal volume and capnography readings of six successive waves. If not properly positioned, minimal manipulation may be done, if not properly positioned yet, removal and re-insertion of the selected device according to each group, if after three attempts, the device is not properly positioned, endotracheal intubation will be done and those patients are excluded from the study. The vital signs (heart rate and mean blood pressure) will be recorded; just prior to device insertion and after connection to capnography , to assess the pressor response during device insertion.

After 3 minutes of adequate oxygenation with 100% oxygen and ventilation and oxygen saturation was 100%, The airway pressure will be assessed in (cmH2O) for each device, with fresh gas flow adjusted at 3 L/min.

to evaluate the seal quality of a supraglottic airway device (LMA). After device insertion and cuff inflation, fresh gas flow is set to 3 L/min, and the adjustable pressure-limiting (APL) valve is closed up to 30 cmH₂O. The pressure at which an audible leak is heard at the mouth or neck, a pressure plateau is observed, or gastric gurgling is detected over the epigastrium is recorded as the OLP. If no leak is detected at 30 cmH₂O, the OLP is noted as ≥30 cmH₂O. This measurement helps determine the safety of using positive pressure ventilation and guides device selection in pediatric anesthesia.(9) A ''puffing'' sound was heard near the patient's mouth (release of pressure) indicating the airway leak pressure .

Anesthesia maintenance will be achieved through the randomly assigned supraglottic device for each group which will be inserted, 2 minimum alveolar concentration of sevoflurane and mixture of gases in proportion 50% oxygen and 50% air.

Postinsertion gastric antral cross-sectional area (CSA) in the supine position will be measured using ultrasound after laryseal pro and ambu aura LMA insertion. The surgery will be allowed to proceed after ensuring proper positioning and sealing of the device.

Then record readings pre and post insertion then compare between 2 devices regarding gastric antral volume.

3.Post operative : The device will be removed and checked for any blood streaked mucous as a sign of airway trauma. Post-operative sore throat or hoarseness of voice will be assessed at 0, 2 and 4h. Any regurgitation, pulmonary aspiration, bronchospasm, hypoxemia will also recorded.

3. Measurement tools

1. LarySeal Pro Laryngeal Mask
2. Ambu AuraGain Laryngeal Mask
3. Syringe for inflation of cuff and insertion of anesthesia drugs
4. Ventilator for supplying with oxygen and gas analyser
5. Monitor to follow vital data of patient
6. Pulse oximeter for measuring Spo2%
7. Capnogram for measuring etco2
8. Anesthesia drugs (propofol)
9. Muscle relaxant (atracurium)
10. Cannula for insertion of drugs
11. Ultrasound
12. Tools:

American Society of Anesthesiologists (ASA) score (Appendix 1) Airway assessment data (Mallampati score) (Appendix 2)

VI. Study outcomes

1. Primary outcome gastric antrum cross-sectional area (CSA) was measured before induction of general anesthesia, before supraglottic airway devices (SAD) insertion, and at the end of surgery before SAD removal.
2. Secondary outcome(s)

1. Incidence of complications (vomiting, bleeding, aspiration, bronchospasm and hoarseness of voice).

2. Time of insertion of supraglottic airway devices 3. Percentage of Failure rate for each device. 4. Monitoring the intraoperative hemodynamics HR and BP every 3 min . 5. Monitoring the intraoperative Oropharyngeal leak pressure. 6. Number of attempts for insertion. Statistical Analysis I. Sample size Based on primary outcome of comparing the gastric insufflation volume between the LarySeal Pro and Ambu AuraGain Laryngeal Masks, a previous study (2) revealed that gastric volume at the end of surgery was 5.91 ml (±9.68 ml) in Ambu AuraGain group and 12.28 ml (±13.05 ml) in the LMA ProSeal group (p= 0.001). Sample size was calculated using G power 3.1.9.7 software using t-test in order to detect the mean difference between groups. A minimum number of 106 patients (53 patients per group based on a two group1:1 design) will be needed to have a study power of 80% and alpha error of 0.05. The number will be increased to 116 patients (58 patients in each group) to compensate for possible 10% dropout rate.

II. Statistical analysis Data will be coded and entered using the statistical package for social science SPSS version 26. Data will be checked for normality using Shapiro-Wilk test. Data will be summarized using number and percent for qualitative variables, mean and standard deviation for quantitative normally distributed variables while median and interquartile range for quantitative not normally distributed variables. Comparison between groups will be done using Chi-square test or fisher's exact test where appropriate for qualitative variables, independent samples T-test and one-way ANOVA for independent comparisons of quantitative normally distributed variables while paired samples T-test and repeated measurements ANOVA for dependent comparisons of quantitative normally distributed variables. For comparing quantitative variables which are not normally distributed; non parametric Mann-Whitney test and Krusskal-Wallis tests will be used for independent comparison and Wilcoxon-signed rank test and Freidman test will be used for dependent comparisons. Correlation will be used for testing linear relations between variables. P value less than or equal to 0.05 will be considered as statistically significant.

Inclusion Criteria:

• • Age: pediatrics (6-12years )

  • Patients with a Mallampati score of I - II
  • Elective surgeries
  • Short procedure expected to last for 1 hour or less .
  • ASA I - II

Exclusion Criteria:

• • Age: below 6 years and above 12 years

  • Patient with airway masses
  • Active upper respiratory tract infections, pneumonia, COPD & exacerbated bronchial asthma.
  • Patient with gastroesophgeal reflux ( hiatus hernia , achalasia )
  • Patient with abnormal airway anatomy
  • Coagulation disorders.
  • Patients with any cardiac conditions (IHD, RHD, decompensated heart failure and arrhythmia).