“Comparison of I-Gel and Laryngeal Mask Airway blockbuster in the management of difficult airway in post burns contracture patients: A randomized controlled trial”

BACKGROUND AND RATIONALE

Patients with post burn contracture (PBC) of the face and neck region usually have a difficult airway, and intubation failure is an important cause of morbidity and mortality during anesthesia in such patients.

Scarring or fibrosis after burns may result in decreased mouth opening and the oropharyngeal cavity, blocked nasal passages, restricted movement of atlantooccipital joint and a flexed neck, trachea which may be deviated/pulled or compressed, and a noncompliant submandibular space. Alignment of the oral, pharyngeal, and the laryngeal axes is required for direct laryngoscopy (DL), hence the above features can make direct laryngoscopy difficult.¹

Supraglottic devices have been found useful to provide adequate airway management in post burn contracture patients. I-gel was found feasible for emergency airway management in difficult airway situation with reduced neck movement and limited mouth opening in post burn neck contracture. ²

A newer LMA called LMA BlockBuster invented in 2012 (Tuoren Medical Instrument co, Ltd, Changyuan city, China) has been gaining popularity to provide increased safety and quality of anesthesia.

Figure 1a. LMA Blockbuster                                1b. i-gel

Singh J,  et al (2012)² conducted a prospective, crossover, randomized controlled trial was performed amongst forty eight post burn neck contracture patients with limited mouth opening and neck movement. i-gel and cLMA were placed in random order in each patient. Success rate for the i-gel was 91.7% versus 79.2% for the cLMA. i-gel required shorter insertion time (19.3 seconds vs. 23.5 seconds, P=0.000). Airway leak pressure difference was statistically significant (i-gel 21.2 cm H20; cLMA 16.9 cm H₂0; P=0.00). Fiberoptic view through the i-gel showed there were less epiglottic downfolding and better fiberoptic view of the glottis than cLMA. Overall agreement in insertion outcome for i-gel was 22/24 (91.7%) successes and 2/24(8.3%) failure and for cLMA, 19/24 (79.16%) successes and 5/24 (16.7%) failure in the first attempt. The i-gel is cheap, effective airway device which is easier to insert and has better clinical performance in the difficult airway management of the airway in the post burn contracture of the neck. Our study shows that i-gel is feasible for emergency airway management in difficult airway situation with reduced neck movement and limited mouth opening in post burn neck.

Gupta S (2017)⁵ conducted a prospective, randomized comparative study total 60 children, 30  each in i-gelâ„¢ and LMA-Supremeâ„¢ group. Oropharyngeal leak pressure (OPLP) for i-gelâ„¢ was found to be significantly higher in flexion (29.00± 1.95cmH₂O, P <0.001) and lower in extension (21.07±2.08 cmH₂O, P < 0.001) as compared to neutral (24.67±2.08 cmH₂O). Similar results were observed for LMA-Supremeâ„¢ which showed significantly higher OPLP in flexion (24.73±2.26, P < 0.001 respectively) and lower in extension (18.67 ± 1.42 cmH₂O, P <0.001) as compared to neutral (20.87 ± 1.80 cmH₂O). Worsening of fiberoptic view occurs for i-gelâ„¢ and LMA-Supremeâ„¢ in flexion (10/12/5/3/0 and 11/14/2/2/1, P <0.05) as compared to neutral position (17/10/2/1/0 and 15/12/1/1/1), respectively. Significant change did not occur in extension. Ventilation worsening occurred in flexion as compared to neutral position evidenced by significant decrease in exhaled tidal volume (92.90 ± 11.42 and 94.13±7.75 ml, P <0.05) as compared to neutral (100.23± 12.31 and 101.50 ± 8.26 ml) for i-gelâ„¢ and LMA-Supremeâ„¢, respectively. Neck flexion caused a significant increase in leak pressure in both i-gelâ„¢ and LMA-Supremeâ„¢. With deterioration of fiberoptic view and ventilation, both devices should be used cautiously in pediatric patients in extreme flexion.

Banerjee G  et al (2018)⁶  conducted a study that total 70 children were randomly assigned to receive PLMA (n = 35) or I-Gelâ„¢ (n = 35) for airway management. Oropharyngeal leak pressure in maximum flexion, maximum extension and the neutral position was taken as the primary outcome. Peak inspiratory pressures (PIPs), expired tidal volume, ventilation score and fibreoptic grading were also assessed.  No significant difference was noted in oropharyngeal leak pressures of PLMA and I-Gelâ„¢ during neutral (P = 0.34), flexion (P = 0.46) or extension (P = 0.18). PIPs mean (standard deviation [SD]) were significantly higher (17.7 [4.03] vs. 14.6 [2.4] cm H₂O, P = 0.002) and expired tidal volume mean [SD] was significantly lower (5.5 [1.6] vs. 6.9 [2] ml/kg, P = 0.0017) with I-Gelâ„¢ compared to PLMA. Fibreoptic grading and ventilation score were comparable in both the groups in all the three head-and-neck positions.  PLMA and I-Gelâ„¢, both recorded similar oropharyngeal leaking pressures in all the three head-and-neck positions. However, higher peak pressures and lower expired tidal volume in maximum flexion of the neck while ventilating with I-Gel may warrant caution and future evaluation.

Endigeri A et al  (2019)⁷ conducted a study that  Sixty patients of age group 20-60 years undergoing general anaesthesia were randomised in 2 groups, of 30 patients each, for tracheal intubation using either BlockBuster^® LMA (Group B) or the Intubating LMA Fastrach^® (Group F). After induction of anaesthesia, LMAs were inserted and on achieving adequate ventilation with the device, fibreoptic scopy was performed to assess the glottis visualisation score. Blind intubation was attempted through the supraglottic airway devices (SAD). The primary objective was first pass successful intubation and secondary outcomes were ease, time for LMA insertion, oropharyngeal seal pressure (OSP), LMA removal time, fibreoptic scoring and complications. Data was analysed using SPSS V22 software.  The first-attempt success rate of tracheal intubation was 90% in Group B and 66.6% in Group F (P = 0.028), while the overall success rate of intubation was 96.6% in Group B and 89.9% in Group F (P = 0.3). The OSP in Group B was 33.7 ± 1.8 and 22.7 ± 1.5 cm H₂O in Group F (P = 0.001). Complications such as sore throat and blood stain were reduced with BlockBuster^® LMA.  BlockBuster^® LMA provides higher first pass success rate of blind tracheal intubation with less complications like sore throat and blood staining.

AIMS AND OBJECTIVES

·        To compare the clinical performance of airway management with i-gel and LMA blockbuster in patients with mild and moderate post burn contractures of neck in adult patients undergoing general anesthesia.

Primary objective:

·        To assess the time taken for insertion of the devices

Secondary objectives:

·        Ease of insertion,

·        Number of attempts (maximum 2),

·        Hemodynamic response and SpO₂ during device insertion and maintenance of General Anesthesia,

·        Airway leak pressures

·        Required attempts for gastric tube placements

·        Any complications

MATERIAL AND METHODS

Study settings:

This prospective randomized controlled study will be conducted in the operating rooms of department of plastic surgery in association with department of anesthesia after obtaining Institutional Ethical clearance and registration of the trial by Clinical Trial Registry of India  (CTRI).

Study type: Prospective Randomized controlled study

Study duration : One year

Sample size: We are planning a study to compare the insertion time of i-gel and LMA for airway management in patients with mild to moderate post-burn contractures. In a previous study, Singh et al. (2012)² reported the insertion time for i-gel and LMA to be 19.4 and 23.5 seconds (Mean difference = 4.1 seconds) respectively in post-burn neck contractures. In present study we will also target a similar difference. The sample size was calculated using the following formula suggested by Charan and Biswas (2013):

n= (r+1) *2(Zα/2+Zβ)2 SD2/d2

where, n: Sample size

r = ratio of study groups = 1:1 = 1; SD: Pooled standard deviation = 5 seconds (Assumed); d: Difference in the means (effect size) = 4.1 seconds

Zα/2 : critical value of z at 95% confidence = 1.96; Zβ: critical value of z at 80% power = 10.84

n = (1+1) * 2*(1.96+0.84)2 * 52 /4.12

= 46.639 » 47

Thus, the calculated sample size is only 47. After adding for a contingency provision of 20% and rounding off to the nearest tenth value we target a sample size of 60 divisible into two equal groups of 30 cases each.

Validation: Projected time of insertion in I-gel group (n=30)= 19.4±5 seconds; Projected time of insertion in LMA group (n=30) = 23.5±5 seconds. Comparison of two using ‘t’-test results in a ‘t’-value of 3.178 with a ‘p’ value 0.002, thus showing that if results projected in index article are replicated then they will be statistically significant too at the estimated sample size.

Inclusion criteria:

·        After obtaining informed consent, 100 ASA physical status I or II patients, 18–60 years of age, having mild or moderate contracture of the neck (Onah’s classification³ Type 1 and Type 2) , with Mallampatti grade I or II and a mouth opening of at least 3 cm, planned for elective surgery under general anesthesia, will be included.

Exclusion Criteria:

·        Patients with any neck pathology other than the scar,

·        Body mass index (BMI) >30 kg/m²,

·        Reactive airway,

·        Gastroesophageal reflux disease,

·        Neck circumference >40 cm, and

·        Pregnant patients will be excluded.

Methodology:

Patients will be randomized using a computer-generated random number and the sealed envelope technique to two groups: group I and group B.

Group I (n=30):– we will use i-gel

Group B(n=30) : we will use the blockbuster LMA.

A thorough pre anesthetic evaluation will be done a day before the procedure and all patients will be advised nil by mouth (NBM) for 8 hours prior to surgery. On the day of surgery, an intravenous access will be established and slow infusion of crystalloids will be commenced. Noninvasive monitors like electrocardiogram, Noninvasive blood pressure (BP), pulse oximetry will be instituted and baseline values of heart rate (HR), BP, oxygen saturation SpO₂ will be recorded and IV cannula of 20G will be placed.

While preoxygenating using 100% oxygen, intravenous injection glycopyrrolate 10 µg/kg, midazolam 0.03 mg/kg, fentanyl 1 µg/kg will be administered. Anesthesia will be induced intravenously with 1% propafol (2 mg/kg). Once an adequate depth of anesthesia will be achieved (loss of eye lash reflex), LMA Blockbuster or i-gel will be inserted. The appropriate size of LMA will be selected according to body weight and manufacturers recommendations.

Adequate placement of the airway device will be assessed by squeezing the reservoir bag and observing the end-tidal CO₂ waveform and movement of the chest wall.

If ventilation will be inadequate, the following manipulations will be done: gentle pushing or pulling the device, chin lift, jaw thrust, head extension, or neck flexion. The ease of LMA placement will be assessed using a subjective scale of 1-4 (1-no resistance, 2-mild resistance, 3-moderate resistance, and 4-inability to place the device). ⁴ Time of insertion will be measured from pickup of device till visible square wave capnograph (with acceptable leak pressures).

The airway will be  manipulated after each attempt if a secure airway will not be achieved. Intervention required on the airway will be graded as either minor [changing neck position/adjusting head (changing depth of inspiration)] or major (requiring jaw thrust, re-insertion/change of device).

Anesthesia will be maintained with 1.5-2.5% Sevoflurane, along with injection Vecuronium intermittently.  After completion of surgery and resumption of adequate spontaneous breathing, the patient would be reverted and the supraglottic device will be removed.  The time of insertion will be measured from the pickup of supraglottic device till visible etCO2 graph and with adequate chest rise and acceptable leak pressure (proper ventilation). The oropharyngeal leak pressures will be measured and compared.

Effective ventilation will be defined as proper chest expansion or square wave capnograph trace, absence of audible leak and lack of gastric insufflations. The total time of placement from grasping of the device to observing a square wave capnograph trace (the insertion time) and the numbers of attempts will be recorded. Airway leak pressure tests will be then performed. The oropharyngeal leak pressure will be measured by closing the expiratory valve of the circle system at a fixed gas flow of 3 litters per minute and noting the airway pressure (maximum allowed 40 cm H₂O). The position of the device will be assessed and graded by the investigators using a fiberoptic bronchoscope (2.8 mm: Olympus, Tokyo, Japan) for the view of glottis. If both the devices failed then fiberoptic bronchoscope will be kept as backup plan for intubation. 

REFERENCES

1)    Prakash S, Mullick P. Airway management in patients with post burn contractures of the neck. Burns. 2015;41:1627–35.

2)    Singh J, Yadav MK, Marahatta SB, Shrestha BL. Randomized crossover comparison of the laryngeal mask airway classic with i-gel laryngeal mask airway in the management of difficult airway in post burn neck contracture patients. Indian J Anaesth. 2012;56:348–52.

3)    Onah II. A classification system for post burn mentosternal contracture. Arch Surg. 2005;140:671–5.

4)    Jagannathan N, Sohn LE, Sawardekar A, Gordon J, Shah RD, Mukherji II et al. A Randomised trial comparing the Ambu Aura-i with air-q^â„¢ intubating LMA as a conduit for tracheal intubation in children. Paediatr Anaesth 2012; 22:156-60

5)    Gupta S, Dogra N, Chauhan K. Comparison of i-gelâ„¢ and Laryngeal Mask Airway Supremeâ„¢ in different head and neck positions in spontaneously breathing pediatric population. Anesth Essays Res 2017;11:647-50

6)    Banerjee G, Jain D, Bala I, Gandhi K, Samujh R. Comparison of the ProSeal laryngeal mask airway with the I-Gelâ„¢ in the different head-and-neck positions in anaesthetised paralysed children: A randomised controlled trial. Indian J Anaesth 2018;62:103-8

7)    Endigeri A, Ganeshnavar A, Varaprasad B V, Shivanand Y H, Ayyangouda B. Comparison of success rate of BlockBuster® versus Fastrach® LMA as conduit for blind endotracheal intubation: A prospective randomised trial. Indian J Anaesth 2019;63:988-94

INFORMED CONSENT

Title of project: Comparison of I-Gel and Laryngeal Mask Airway blockbuster in the management of difficult airway in post burns contracture patients: A randomized controlled trial

Investigators:

Dr Manish Kumar Tripathi, JR-1, Department of Anaesthesiology, KGMU, Lucknow.

Mob No. 9670986299; email ID: tripathi.manish81@gmail.com

Chief Supervisor: Dr. Tanmay Tiwari, Associate Professor,  Department of Anaesthesiology, KGMU, Lucknow

Co-supervisors: Dr. Divya Narain Upadhyay, Additional Professor,  Department of Plastic Surgery, KGMU, Lucknow

Dr.Prem Raj Singh, Associate Professor,  Department of Anaesthesiology, KGMU, Lucknow

Subject’s Full Name ________________________________________________

 Date of Birth/Age_________________________________________________

Address _________________________________________________________

Patient/Parent/Guardian Consent PART 1

Purpose of the study- To compare the clinical performance of airway management with i-gel and LMA blockbuster in patients with mild and moderate post burn contractures of neck in adult patients undergoing general anesthesia.

Study Procedure:  Prospective Randomized control study  

Risk from the study-None

Benefits from the study-  This study to assess the time taken for insertion of the devices; Ease of insertion, Number of attempts (maximum 2),  Hemodynamic response and SpO₂ during device insertion and maintenance of General Anesthesia, Airway leak pressures, Required attempts for gastric tube placements and  Any complications.

Complications–None

Compensation-none

Confidentiality- all the information and clinical documents of subjects of the study will be kept strictly confidential and will be shown only to the investigator, supervisor and co- investigators of the study. The result of study will be used for clinical and academic purpose and the name of the subject would not be disclosed.

Rights of the participants- Participation in the study is voluntary. Refusal to participate will not influence the care of patient in this hospital in any way.

Alternatives to participation in the study-None

PART 2

Consent

1        I confirm that I have read and understood the information sheet dated ___________for the above study and have had the opportunity to ask questions.

OR

I have been explained the nature of the study by the Investigator and had the opportunity to ask questions

2        I understand that my participation in the study is voluntary and that I am free to withdraw at any time, without giving any reason and without my medical care or legal rights being affected.

3        I understand that the sponsor of the clinical trial/project, others working on the Sponsor’s behalf, the Ethics Committee and the regulatory authorities will not need my permission to look at my health records both in respect of the current study and any further research that may be conducted in relation to it, even if I withdraw from the trial. However, I understand that my Identity will not be revealed in any information released to third parties or published.

4        I agree not to restrict the use of any data or results that arise from this study provided such a use is only for scientific purpose(s)

5.  I agree to take part in the above study

Signature (or Thumb impression) of the Subject/Legally Acceptable Representative:___________________

Signatory’s Name:______________________________

Date:_____________________________

Relationship with subject:_______________________________

Investigator’s statement:-

I, the undersigned have explained to the parent/guardian in a language she/he understands the procedures to be followed in the study and risks and benefits.

Signature of the Investigator:                                                       Date:

Name of the Investigator:

Signature of the Witness:                                                               Date:

Name of the Witness:

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