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i-gel vs Endotracheal Tube (ETT): Detailed Comparison

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1. Device Overview

i-gel (Second-Generation Supraglottic Airway Device)

• Introduced clinically in 2007
• Composed of a soft, gel-filled, non-inflatable cuff made of thermoplastic elastomer that conforms to the perilaryngeal anatomy
• Includes an integral bite block, a narrow-bore gastric drain tube, and a buccal cavity stabiliser strap (adult sizes)
• Lies above the glottis (supraglottic) - does NOT enter the trachea
• Classified as a second-generation SAD, like the ProSeal LMA and LMA Supreme

Endotracheal Tube (ETT)

• A cuffed tube passed through the glottis directly into the trachea
• High-volume, low-pressure cuff inflated with air to seal the trachea
• Provides a definitive, sealed airway conduit
• Requires direct or video laryngoscopy for placement in most cases
• Considered the gold standard for definitive airway management

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2. Advantages and Disadvantages - Head to Head

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A. Insertion

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B. Airway Seal and Ventilation

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C. Aspiration Protection

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D. Haemodynamic Response

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E. Postoperative Complications

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F. Specific Clinical Settings

Laparoscopic Surgery

• ETT: Traditionally preferred for laparoscopic procedures, especially in obese patients, as it tolerates higher pressures needed with pneumoperitoneum
• i-gel/2nd gen SADs: Growing evidence supports use in laparoscopic cholecystectomy in non-obese patients; lower pain scores, less PONV, smoother emergence. However, somewhat less effective than ETT in the obese. - Miller's Anesthesia, 10th Ed., p. 9991

Difficult Airway

• ETT: The definitive goal, but insertion may be impossible without aids
• i-gel: Can act as a rescue airway and a conduit for fibreoptic intubation; used in cannot-intubate situations. ILMA version facilitates blind or fibreoptic ETT passage through it.

Emergency/Pre-hospital

• i-gel: Faster, no laryngoscopy, usable by paramedics, lower risk of oesophageal intubation - preferred when advanced airway skills may be limited
• ETT: Definitive, but requires trained provider, risk of unrecognised oesophageal intubation

ENT/Head-Neck Surgery (Shared Airway)

• ETT: Preferred - provides secure, protected airway when the airway is "shared" with the surgeon
• i-gel: More restricted use; cannot provide the same protection in mouth, nose, or laryngopharyngeal surgery where blood from above may soil the lungs. - Scott-Brown's Otorhinolaryngology, 9th Ed., p. 384

Cardiorespiratory Resuscitation

• i-gel: Used widely in CPR - allows hands-free ventilation, faster insertion, acceptable ventilation during resuscitation
• ETT: More definitive but takes time and interrupts compressions

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G. Oxygenation and ETCO₂ Monitoring

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3. Summary Comparison Table

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4. When to Choose Which

• Elective, short-to-medium procedures in fasted, non-obese patients (ASA I-II)
• Spontaneous or low-pressure controlled ventilation required
• Patient has cardiovascular disease/raised ICP (haemodynamic stability important)
• Difficult airway rescue or as a conduit for fibreoptic intubation
• Pre-hospital/emergency setting by less-trained providers
• Reducing postoperative pharyngolaryngeal morbidity is a priority

• Full stomach / risk of regurgitation (RSI setting)
• Obese patients, difficult airway requiring definitive securing
• High airway pressures needed (ARDS, poor compliance, obese, laparoscopic in obese)
• Prolonged surgery or ICU mechanical ventilation
• Head, neck, ENT, or intraoral surgery (shared airway)
• Prone positioning requiring highly secured airway
• Neurosurgery with raised ICP (where hypoventilation from a leak could be catastrophic)

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• Miller's Anesthesia, 10th Ed., pp. 9991-9993
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, 9th Ed., pp. 383-384
• Bailey and Love's Short Practice of Surgery, 28th Ed.
• Kanakaraj et al., Br J Anaesth 2024 - Network meta-analysis of 29 SGAs (PMID: 39406569)
• Clinical Comparison of i-gel and Cuffed ETT for Pressure-Controlled Ventilation, PMC5656161

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Types of Supraglottic Airway Devices (SADs)

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Classification Systems

1. Cook's Generation Classification (Most Widely Used)

2. Brimacombe's Classification

• Presence or absence of a cuff
• Mode of insertion (oral or nasal)
• Anatomic location of the distal portion relative to the hypopharynx

3. Miller's Classification

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FIRST-GENERATION SADs

1. Classic LMA (cLMA)

• Invented by Dr. Archie Brain (UK), introduced ~1983
• Oval inflatable cuff attached to an airway tube; cuff inflates to seal around glottic opening
• First SGA ever used clinically; transformed anaesthesia practice
• Placement: lubricated cuff advanced blindly along hard palate into oropharynx until resistance felt, then cuff inflated
• OLP (oropharyngeal leak pressure): ~18-20 cmH₂O
• Advantage: Reliable airway maintenance, low trauma, usable by non-anaesthetists, suitable for spontaneous and low-pressure ventilation
• Disadvantage: No gastric drain, no protection from aspiration, unsuitable for high-pressure ventilation
• Sizes: 1 (neonates) to 6 (large adult)

2. LMA-Unique

• Disposable single-use version of the cLMA
• Same design, avoids risk of cross-contamination
• Widely used in routine elective surgery

3. Flexible LMA (Reinforced LMA / Wire-reinforced)

• Armoured, flexible wire-reinforced shaft that can be moved without displacing the cuff
• Resistant to kinking and compression
• Can be positioned away from the surgical field (ENT, dental, head-neck procedures)
• Advantage: Tube can be repositioned; doesn't obstruct surgical access
• Disadvantage: More difficult to insert than cLMA; flexible shaft makes it harder to guide during placement

4. CobraPLA (Perilaryngeal Airway)

• Wide, cobra-shaped distal tip that sits in the oropharynx
• Provides a wider airway channel
• Used in short procedures, less commonly available now

5. Laryngeal Tube (LT) / King LT

• Tube with two cuffs (pharyngeal and oesophageal) that together isolate the larynx
• Popular in pre-hospital/EMS setting
• Variants: LT-D (disposable), King LTS-D (second gen with gastric access)

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SECOND-GENERATION SADs

• A gastric drain tube for decompression and suction
• Improved cuff seal (higher OLP, better positive pressure ventilation)
• Integral bite block to prevent occlusion
• Better protection against aspiration compared to first-generation

1. LMA ProSeal (PLMA)

• Two cuffs: anterior cuff (same as cLMA) + additional posterior cuff that pushes mask against glottis from behind
• Integral gastric drain tube for decompression or NGT passage
• OLP: 29-30 cmH₂O (significantly higher than cLMA)
• Advantage: Better seal, suitable for laparoscopy, better aspiration protection, ideal for prone patients
• Disadvantage: Requires introducer or digital technique; heavier, reinflatable cuff needs careful management; not suitable for blind intubation

2. LMA Supreme

• Single-use, pre-curved rigid design (fits anatomical curve of oropharynx)
• Integral gastric drain tube + bite block
• OLP: ~24-28 cmH₂O
• Easier to insert than ProSeal (no introducer needed); good first-attempt success
• Advantage: Quick insertion, disposable, suitable for moderate-pressure ventilation
• Disadvantage: Pre-curved rigid shaft less adaptable; not for prolonged use

3. i-gel (Intersurgical, 2007)

• Non-inflatable thermoplastic elastomer cuff that conforms anatomically to the perilaryngeal structures
• Narrow-bore gastric drain tube + integral bite block + buccal stabiliser strap
• OLP: ~24-27 cmH₂O (intermediate between 1st and 2nd gen SADs)
• No inflation required - no syringe, no pilot balloon
• Advantage: Fastest insertion, no inflation errors, less pharyngeal trauma, low sore throat rate (6-12%), usable by paramedics; acts as conduit for fibreoptic intubation
• Disadvantage: Limited seal at pressures >20 cmH₂O; cuff not adjustable; less effective in obese patients

4. Combitube (Oesophageal-Tracheal Combitube)

• Dual-lumen tube with two cuffs (pharyngeal and oesophageal)
• Can ventilate whether placed in oesophagus (most common) or trachea
• Useful in emergency, pre-hospital settings or when intubation fails
• Advantage: Can ventilate regardless of insertion site; protects from regurgitation
• Disadvantage: Bulky, difficult to use, largely replaced by newer SADs; not suitable for paediatrics

5. King LTS-D (Laryngeal Tube Suction - Disposable)

• Dual-cuff design (similar to laryngeal tube) + gastric drain access
• Popular in EMS/paramedic use
• Good seal pressure; easy insertion

6. AuraGain (Ambu)

• Second-generation SAD with gastric drain tube and reinforced tip
• Can function as intubating conduit (allows ETT passage)
• Increasing popularity due to intubation capability

7. air-Q (Intubating SAD)

• Wide-bore airway shaft designed specifically as an intubating conduit
• No epiglottic bars (common in classic LMA), allowing ETT passage
• Self-pressurizing cuff design (3rd gen feature claimed by some)
• Both disposable (air-Q sp) and reusable versions
• Used in difficult airway algorithms as a bridge to intubation

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INTUBATING SADs (Separate Functional Category)

1. ILMA / LMA Fastrach

• Invented by Dr. Archie Brain (1997); first intubating SGA
• Rigid, curved metal handle; wide airway tube with epiglottic elevating bar
• Allows blind or fibreoptic tracheal intubation through the device
• Specially designed silicone ETT (wire-reinforced) passes through ILMA
• Insertion technique uses "Chandy manoeuvre" (two-step adjustment for optimal position)
• OLP: ~24 cmH₂O
• Advantage: Permits ventilation between attempts; high blind intubation success; suitable for unexpected difficult airway
• Disadvantage: Significant learning curve; rigid design causes high tissue pressure - should be removed promptly after intubation; not reusable for long durations

2. Classic LMA as intubation conduit

• Not designed for intubation but can be used with a fibreoptic scope
• Requires microlaryngeal tube (narrow) due to long/narrow shaft
• Or used with Aintree Intubation Catheter + FIS for ETT exchange

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THIRD-GENERATION SADs (Emerging)

1. Baska Mask

• Novel gastric drain design with a non-inflatable, self-pressurizing cuff (passive inflation by respiratory pressure)
• Very high OLP (~35+ cmH₂O); among highest of any SAD
• Separate drain tubes; integral bite block
• Best-ranking SAD for OLP in the 2024 BJA Network Meta-analysis (12,045 patients)

2. SaCoVLM (Video Laryngeal Mask)

• Second-generation SAD body + integrated reusable videoscope in a dedicated channel
• Three channels: ventilation, gastric drainage, visual/video
• Allows real-time visualisation of the glottis AND fibreoptic intubation under vision
• Reduces blind tube placement risk

3. SafeLM Video Laryngeal Mask System

• Similar design to SaCoVLM with flexible-tipped videoscope
• Enables visually guided intubation through the SAD

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Summary Overview Table

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Key Anatomical Principle

1. Maintaining airway patency without laryngoscopy
2. Allowing spontaneous or assisted ventilation
3. Permitting gas exchange at pressures below the oropharyngeal leak pressure (OLP)

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Types of Supraglottic Airways - Quick Summary

1st Generation - Simple airway, no aspiration protection

• Classic LMA, LMA-Unique, Flexible (Reinforced) LMA, CobraPLA, Laryngeal Tube (King LT)

2nd Generation - Adds gastric drain + better seal + bite block

• i-gel, LMA ProSeal, LMA Supreme, Combitube, King LTS-D, AuraGain, air-Q

Intubating SADs - Primary function is tracheal intubation

• LMA Fastrach (ILMA), air-Q, AuraGain

3rd Generation - Adds dynamic seal or integrated video

• Baska Mask, SaCoVLM (Video LMA), SafeLM VLMS

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• Cuff type and design
• Oropharyngeal leak pressure (OLP)
• Advantages and disadvantages
• Key clinical indications
• A full comparison table

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Types of Supraglottic Airway Devices (SADs)

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🔹 First Generation — Simple airway tube, NO aspiration protection

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🔹 Second Generation — Gastric drain tube + better seal + bite block

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🔹 Intubating SADs — Designed primarily as conduit for tracheal intubation

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🔹 Third Generation — Dynamic seal OR integrated video

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Key Principle

All SADs: distal tip in proximal oesophagus → cuff seals around arytenoids/perilaryngeal structures → lumen aligns with glottis

• LMA protects from pharyngeal secretions but NOT gastric regurgitation
• Only 2nd gen devices (with gastric drain) offer improved (not complete) aspiration protection
• Ventilation is effective only when peak inspiratory pressure < oropharyngeal leak pressure (OLP)

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