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  1. AMBU BAG –
    1. Artificial manual breathing unit (capacity 1200 ml)
    2. Max. O2 that can be given by AMBU Bag – 100%
  2. Instruments to preserve Humidity
    1. Water content of inhaled air at 37oC – 44 mg/L
    2. Water content of inhaled air at 21oC – 9 mg/L
    3. Water content of 100% O2 – O
    4. Complete caseation of mucociliary activity occurs <22 mg/L
      Various method of preserve humidity are
      1. Heat and moisture exchanger (also called as artificial nose)
      2. Humidifiers
      3. Nebulizers (optimal size 0.5-5 microns)
  3. Scavenging system is used to eliminate the excessive anaesthetic gases
    Max. allowable conc. Of waste gases
    1. N2O <25 ppm
    2. Halogenated agents < 2 ppm
    3. N2O + halogenated agents <25 ppm & <0.5 ppm
  4. Airways
    1. Most commonly used airway – Guedel
    2. Length of airway = Distance between tip of nose & tragus + 1 inch
  5. Laryngoscope
    Commonly used laryngoscope is Macintosh (curved blade) neonates – straight blade (magill)
    Head & neck position for laryngoscope is extension at Atlanto-occipital joint & flexion at cervical spine
    Teeth most vulnerable to damage is upper incisors

E.T. Intubation

Endotracheal intubation is the placement of a tube into the trachea to maintain a patent airway in those who are unconscious or unable to maintain their airway for other reasons. Compared to the use of pharyngeal airways (oropharyngeal or nasopharyngeal), benefits of an endotracheal airway include:
  • Protection against aspiration and gastric insufflation
  • More effective ventilation and oxygenation
  • Facilitation of suctioning
  • Delivery of anaesthetic and other drugs via the endotracheal tube (ETT)

Technique of Intubation

  1. The patient should lie supine.
  2. There should be extension at Atlanto – occipital joint and flexion at lower cervical spine. Position is called morning sniffing position.
  3. This position is achieved by putting a 6 to 8 cm thick pillow under the occiput.
  4. The laryngoscope blade should be inserted from right side of mouth and advanced slowly displacing the tongue to left until epiglottis is visualized.
  5. Once the epiglottis is visualized it is lifted anteriorly to visualize glottis. Once the glottis is seen the endotracheal tube is passed between the cords.
  6. The cuff is inflated and the cuff should be midtracheally and well below vocal cords in adults.
  7. The position of tube is verified by capnography and auscultation over chest for air entry.
  8. The tube should be well secured at the angel of mouth with adhesive tape or bandage.
  9. Reflex response to laryngoscopy and intubation: During laryngoscopy and intubation there may be laryngospasm, bronchospasm, severe hypertension, tachycardia and cardiac arrhythmias.
  10. Blunting of these cardiovascular responses is mandatory in hypertensives and cardiac patients.
  11. Methods applied to blunt these cardiovascular responses are:
    1. Adequate depth of anaesthesia.
    2. Opioids especially fentanyl
    3. Intravenous Lignocaine 2% (1mg/kg) 2 to 3 minutes before intubation.
    4. Local Lignocaine spray.
    5. b Blockers (esmolol).
  12. Cuff Pressure
    1. It should be less than 30 cm H2O to revent tracheal ischemia.
    2. During nitrous oxide inhalation, the nitrous oxide can diffuse in air filled cuff and can increase the cuff pressure.
    3. In children less than 5 years of age uncuffed tubes should be used and there should be slight leak on inspiratory pressure of 30 cm H2O (that means tube should not be so tightly fit).
    4. Cuff should be filled with saline (instead of air) when tube is used for laser surgeries, and when hyperbaric oxygen is used.
    5. The cuff should be 2 to 2.5 cm below vocal cords.

Extra Edge: The cuff pressure during endotracheal intubation in children should not be raised above 30cm. of water or 22mmHg. to prevent ischemic damage to tracheal mucosa.

  1. Complication
    • Laryngoscopy:
      • Mechanical
        • Damage to teeth, lips, gums or other soft tissues.
        • Oedema of tissues (usually the result of multiple intubation attempts).
        • Coughing, laryngospasm, bronchospasm, vomiting (with a risk of aspiration).
        • Hyperextension cervical injury.
        • Temporomandibular joint dislocation.
      • Physiological
        • Cardiovascular responses - hypotension, hypertension, tachyarrhythmias, bradyarrhythmias in children.
        • Respiratory responses - coughing, laryngospasm, bronchospasm.
        • Raised intracranial pressure.
        • Hypoxaemia / hypercarbia - especially with difficult intubation or prolonged attempts.
    • Tracheal Intubation
      • Failed intubation and hypoxaemia:
        • Can ventilate with a mask - seek senior help, defer intubation or consider an alternative.
        • Can't ventilate - call for urgent assistance; if bag and mask ventilation is maintaining oxygen saturations above 90% and there is adequate time, consider other options such as the use of a bougie to guide ETT placement; or alternatives such as the use of LMA or Combitube or fibreoptic induction or, if not, cricothyoidotomy. See example of a failed airway algorithm.
      • Misplaced intubation – oesophageal or right mainstem intubation
      • Obstruction - kinking of endotracheal tube, cuff over inflation or herniation, presence of blood, mucus or foreign body.
      • Mechanical damage - to pharynx, larynx, vocal cords, trachea, or oesophagus (including oesophageal dissection and perforation).
      • Aspiration and post-intubation pneumonia.
      • Pneumothorax
Deciding the size of endotracheal tube
  1. In a normal healthy male usually 9 number (means internal diameter 9 mm) tube is used and for normal healthy female usually 8 number tube is used. In children the size is of endotracheal tube (in mm internal diameter (ID) is as follows:
    a. Prematures : 2.5 mm ID
    b. 0 to 6 months : 3 to 3.5 mm ID
    c. 6 months to 1 year : 3.5 to 4 mm ID
  2. In children the size is calculated as follows:
    1. For children between 1 year to 6 year,
      The size is calculated by formula
       + 3.5 mm ID
    2. For children above 6 year,
      The size is calculated by formula

       + 4.5 mm ID
    3. For example for a 5 year old child the tube size required will be
       + 3.5 = 1.6 + 3.5 = 5.1 (means 5 number tube)
  3. Remember the following features of infant larynx in contrast to adult larynx (MCQs):
    1. Epiglottis is long and leafy.
    2. Subglottic region is the narrowest portion of larynx.
    3. Larynx is placed at a higher level (in adults, it is placed at the level of C3-C6 vertebrae).
    4. Smallest size of tube available is 2.5 mm and the largest size 10.5 mm
  4. For calculating the length of tube
    Clinically the length is considered adequate at which the air entry is equal on both sides of chest. Usually it is 23 cm in adult males and 21 cm in adult females (or in other words tip of the tube should lie 4 to 5 cm above the carina because distance between incisors and carina is 26 to 28 cm). A rough guide is that length is twice the length from tip of nose to ear lobule.
    • In children, the length of oral tube is calculated by formula:
       + 12 cm
  5. For calculating length for nasal intubation 3 cm is added to oral length:
    1. For 5 year old child length will be

Other types of tubes in common use

  1. R. A. E. preformed tubes (R.A.E. after the name of 3 scientists Ring, Adair and Elwyn):
    1. South facing: Used for upper cleft lip and cleft palate surgery
    2. North facing: used for lower lip surgery.
  2. Spiral embedded (also called as flexometallic armored tube):
    These are non kinkable. Non collapsible so used for head and neck surgeries. Where acute flexion of neck is required.
  3. Microlaryngeal and laryngotracheal surgery tube
    (MTNL, LTS tubes): Used for micro laryngeal surgeries.
  4. Coles tube: Used for children, the distal end of tube has narrow diameter (because in children narrowest part is subglottis)
  5. Endotrol tube: Angle of tip can be changed, so excellent for nasal intubation.
  6. Double lumen tubes: Robertshaw’s and carlens, used for thoracic surgery where one lung anaesthesia is required.
  7. Combitube: It is double lumen tube used for providing patent airway in emergency and difficult intubation

Checking the position of endotracheal tube

  1. Direct visualization,
  2. Chest Wall motion,
  3. Sounds of Air around the tube,
  4. Moisture Condensation in the Tracheal Tube,
  5. Oxygenation,
  6. Palpation of Suprasternal Notch,
  7. Tactile Confirmation,
  8. Ultrasound,
  9. Tracheal Palpation during the intubation,
  10. Exhaled Carbon Dioxide
  11. Feel of the reservoir bag
  12. Auscultation
  13. Epigastric Distention
  14. Gastric Contents in Tracheal Tube
  15. Chest X-Ray
  16. Use of Fiberscope
  17. Esophageal Detector Devices
  18. Passing Introducer through Tracheal Tube
  19. Pressure and flow volume loops
confirmation of correct placement of DOUBLE LUMEN tube is by fibreoptic bronchoscope


Note: Sudden decrease in end-tidal CO2 as shown by capnography suggests accidental extubation.

Complications of endotracheal tube

  1. Trauma,
  2. Esophageal intubation,
  3. Airway perforation,
  4. Leakage,
  5. Bacteremia,
  6. Failure to achieve a satisfactory seal
  7. Bronchial Intubation
  8. Murphy eye choking
  9. Accidental Extubation
  10. Postoperative sore throat

Note: Restricted TM joint mobility, short mandible and laryngeal webs - all can cause difficulty in intubation.


Double lumen tube – Robertshaw and White and Carlen,

Causes of inadequate ventilation

  1. Disconnection in the circuit, 
  2. Kinking of the circuit,
  3. Empty cylinder,
  4. Chest wall rigidity
  5. Obstruction in the circuit
  6. Inadequate gas supply
  7. Bronchospasm and Laryngospasm

Sterilization of anaesthesia equipments

  1. Laryngoscope stylets magill forceps can be autoclaved
  2. Other for all instruments ethylene oxide gas sterililzation is best
  3. 2nd choice – 2% Glutraldehyde
  4. 3rd Choice – ethyl alcohol 70%

Laryngeal mask airway 

The laryngeal mask airway (LMA) is a supraglottic airway device developed by British Anesthesiologist Dr. Archi Brain. It has been in use since 1988. Initially designed for use in the operating room as a method of elective ventilation, it is a good alternative to bag-valve-mask ventilation, freeing the hands of the provider with the benefit of less gastric distention. Initially used primarily in the operating room setting, the LMA has more recently come into use in the emergency setting as an important accessory device for management of the difficult airway.
The LMA is a good airway device in many settings, including the operating room, the emergency department, and out-of-hospital care, because it is easy to use and quick to place, even for the inexperienced provider. It has a success rate of nearly 100% in the operating room, although this may be lower in the emergency setting. Its use results in less gastric distention than with bag-valve-mask ventilation, which reduces but does not eliminate the risk of aspiration. This may be particularly pertinent in patients who have not fasted before being ventilated.
Laryngeal mask airways come in several types.
  • The LMA Classic is the original reusable design.
  • The LMA Unique is a disposable version, making it ideal for emergency and prehospital settings.
  • The LMA Fastrach, an intubating LMA (ILMA), is designed to serve as a conduit for intubation. Although most LMA designs can serve this purpose, the LMA Fastrach has special features that increase the rate of successful intubation and do not limit the size of the endotracheal tube (ETT). These features include an insertion handle, a rigid shaft with anatomical curvature, and an epiglottic elevating bar designed to +--lift the epiglottis as the ETT passes.
  • The LMA Flexible has softer tubing. It is not used the in the emergency setting.
  • The LMA ProSeal has the addition of a channel for the suctioning of gastric contents. It also allows for 50% higher pressures without a leak. However, it does not permit blind intubation and is not currently used in the emergency setting.
  • The LMA Supreme, which is a newer design, is similar to the ProSeal and has a built-in bite block.
  • Another newer design is the LMA CTrach, which inserts like the LMA Fastrach and has built-in fiberoptics with a video screen that affords a direct view of the larynx.

Advantage and disadvantage of LMA over Endotracheal tube



Supraglottic airway device

Infraglottic airway device

Easy to insert even by inexperienced hand

Needs more expertise to insert

Fast to insert

Needs more time

Less airway response

More sympathetic stimulation

Needs lesser depth of anaesthesia

Deeper plane of anaesthesia required

Less invasive

More invasive

More chances of aspiration

Less chances of aspiration


Proseal LMA- It is the best variant of LMA. It is comparable to endotracheal tube in preventing aspiration. It is very frequently nowerdays being used for laproscopic surgery and abdominal surgery.
Recommended Size guidelines for classical LMA:
  1. Size 1: under 5 kg
  2. Size 1.5: 5 to 10 kg
  3. Size 2: 10 to 20 kg
  4. Size 2.5: 20 to 30 kg
  5. Size 3: 30 kg to 50kg
  6. Size 4: 50-70kg
  7. Size 5: >70 kg
  8. Size 6: >100kg

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