Management of

Difficult Airway

SLCOA National Guidelines

Contents
List of Contributors 08

Introduction 09

Objectives 09

Definitions 10

Assessment and preparation for tracheal

intubation 11

Difficult airway drills 17

Adult non-obstetric difficult airway management drill 17

Obstetric difficult airway management drill 26

Management of acute upper airway obstruction 32

Management of desaturation under anaesthesia 37

Extubation & Follow up 41

References 44

List of Contributors
Dr. Deepthi Attygalle
Dr. Hemantha Rajapakse
Dr. Kalum Ranatunge
Dr. Nalini Rodrigo
Dr. Nilmini Wijesuriya

SLCOA National Guidelines

2 Management of difficult airway
2.1 Introduction
The incidence of difficult tracheal intubation following induction
of general anaesthesia is rare and has been estimated at 3-18%. It
is the most critical emergency that an anaesthetist can be faced
with and may lead to hypoxaemic anaesthetic death, brain damage
or serious soft tissue damage. When the junior anaesthetist is
confronted with an unanticipated difficult tracheal intubation
especially out of hours he should concentrate on maintenance of
oxygenation and prevention of airway trauma until senior help
arrives.
These guidelines will address the following aspects:

These guidelines are constructed with regard to the culture, skill

and equipment available in Sri Lanka. Therefore some equipment
that are mentioned in standard text books or guidelines formulated
in other countries may not be included. That does not preclude the
anaesthetist to use them if and when available and if adequately
experienced in using them. Wall charts have been produced to use
in conjunction with these guidelines for quick reference.

2.2 Objectives
These guidelines are formulated to help the non-specialist
anaesthetic medical officers to manage different clinical scenarios
associated with unanticipated difficult tracheal intubation in adults.
Although these scenarios may be multifactorial, a structured
sequence of actions would detect most of the causes. Children
with unpredicted difficult airways should be managed by a
consultant at an early stage. Management of predicted difficult
airway is not within the scope of the non-specialist anaesthetist
and he should always discuss such cases with the consultant
anaesthetist. When specialist opinion is not available the patient
should be transferred to the nearest hospital where a consultant is
available, preferably after discussion and stabilization.

SLCOA National Guidelines / Difficult Airway 9

2.3 Definitions
2.3.1 Difficult airway: the clinical situation in which a
conventionally trained anesthetist experiences difficulty with face
mask ventilation, laryngoscopy, tracheal intubation or fails to
intubate the trachea.
A difficult airway may be caused by several factors:

• patient factors
• clinical setting
• skills of the practitioner

2.3.2 Difficult face mask ventilation: Inability of an unassisted

anaesthetist to maintain oxygen saturation (SpO2) more than 90%
with positive pressure mask ventilation using 100% oxygen in a
patient whose oxygen saturation (SpO2) was more than 90% before
induction and/or it is not possible to prevent or reverse signs of
inadequate ventilation with positive pressure mask ventilation.

• This may occur due to one or more of the following

problems: inadequate mask seal, excessive gas leak, or excessive
resistance to the ingress or egress of gas.

• Signs of inadequate face mask ventilation: absent or

inadequate chest movement, absent or inadequate breath sounds,
auscultatory signs of severe obstruction, cyanosis, gastric air entry
or dilatation, decreasing or inadequate oxygen saturation (SpO2),
absent or inadequate exhaled carbon dioxide, and haemodynamic
changes associated with hypoxaemia or hypercarbia (e.g.,
hypertension, tachycardia, arrhythmia).

• 2.3.3 Difficult laryngoscopy: Inability to visualize any

portion of the vocal cords after multiple attempts at conventional
laryngoscopy. (Cormack and Lehane laryngoscopy grade 3 or 4)

10 SLCOA National Guidelines / Difficult Airway

• 2.3.4 Difficult tracheal intubation: Tracheal intubation
which requires more than 3 attempts, or more than 10 minutes
with a conventional laryngoscope.

• 2.3.5 Failed intubation: Placement of the endotracheal

tube fails after multiple intubation attempts.

2. 4 Assessment and preparation for tracheal

intubation following routine induction of
general anaesthesia in a non-obstetric patient

2.4.1 Pre-operative Assessment of the airway

All patients should undergo an airway evaluation pre-surgery
and this should be recorded on the anaesthesia record. But
this assessment is imperfect in predicting problems always,
so an airway strategy should be drawn up for each patient to
cover the entire period of anaesthetic care, particular at the
start and end of anaesthesia.

History
• Intubation problems during previous
anaesthetics
• Neonates, elderly, pregnant women
• Facial/maxillary trauma, cervical spine injury,
previous surgery
• Snoring and sleep apnoea
• Infection or inflammation, orofacial or neck
oedema
• Rheumatoid disease or surgery of the neck or
degenerative spinal diseases
• Tumours, radiation-related scarring, burns

SLCOA National Guidelines / Difficult Airway 11

 Physical examination: Any factor which interferes
with the line of vision

• Buck teeth, missing or loose teeth, especially upper

left incisors)
• Inability to extend the head in the erect position
• Short neck
• Receding mandible (anterior larynx)
• Inability to protrude the lower jaw

Special tests
• Mallampati grade, (also checks the degree of mouth
opening, size and mobility of the tongue and other
structures in the mouth; Grade e” 3)
• Thyromental distance (< 6.5 cm or < 3 finger
breaths)
• Sterno-mental distance < 12.5 cm
• Delikan’s sign

See Reference pp. 4-4 for more details (with permission)

If preoperative assessment indicates the possibility of a difficult

airway, aspiration prophylaxis should be given and the
consultant anaesthetist should be consulted. Junior medical
officers should not handle a predicted difficult airway in the
absence of a consultant anaesthetist.

2.4.2 Preparation for difficult airway

management
Anaesthetists should be ready to deal with difficulties in
intubation at any time. The correct equipment, drugs and trained
personnel must be immediately available. This will include:

12 SLCOA National Guidelines / Difficult Airway

2.4.2 (a) Personnel
• A trained anaesthetist (conventionally trained for 6 months
and approved by a consultant anaesthetist to be satisfactory).
Intubation with a bougie should be practiced simulating a
Lehane & Cormack Grade 3.
• A trained assistant: as there are no trained operating
department assistants in government hospitals, a nurse or a
suitable minor employee should be trained for this purpose
when the anaesthetist is on his own.
2.4.2 (b) Recommended equipment for routine airway
management
The following list of equipment is recommended for routine
intubation.

• Adjustable operating table or trolley

• Wee’s detector (Oesophageal detector device)
• ECG, pulse oximetry, NIBP, capnography,
stethoscope
• Oxygen source and tubing
• Anaesthetic breathing system / Ambu bag
• Reliable suction equipment
• Facemasks
• Oropharyngeal/ Nasopharyngeal airways: three sizes
• Laryngeal Mask Airways
• Two working laryngoscope handles with a selection
of blades
• A variety of endotracheal tubes in a range of sizes,
and tape or ties for securing the ETT
• Tracheal tube introducer (“gum-elastic” bougie)
• Magill’s forceps
• Malleable stylet
• A cricothyroidotomy kit

SLCOA National Guidelines / Difficult Airway 13

2.4.2 (c) Drugs
• Appropriate induction/sedative/ paralytic agents
• Essential emergency drugs

2.4.2 (c) Difficult intubation trolley

• A cart containing the following equipment should be
located no more than a couple of minutes from every
location where anaesthesia is administered.
• All anaesthetists and anaesthetic assistants should be
familiar with the contents and location of the trolley.
• Equipment should be pre assembled & ready to use.
• Equipment should be arranged sequentially in a specially
designed trolley with clearly labeled difficult intubation
drills displayed

All equipment should be sequentially arranged as follows if

possible:

14 SLCOA National Guidelines / Difficult Airway

1. Top drawer- • Laryngoscopes
Difficult intubation Mackintosh blade (standard & left
equipment handed)
Sizes 3, 4
Miller sizes 2, 3
McCoy sizes 3, 4
Short handle
• Malleable stylet
• ET tubes of all sizes (cuffed &
uncuffed)
• Light wand Trachlight (if
available)

2.Side • Gum elastic bougies,

compartment • Suction catheters
• Magill’s forceps
• Cook exchange catheters
• Fiberoptic accessories(Bermann
airways/ swivel connectors)
3. 2nd drawer - • Guedel/nasopharyngeal airways
Difficult ventilation • Special ET tubes -armoured/
equipment microlaryngeal

4. 3rd drawer • LMA Classic (Sizes3,4,5)

• Proseal with introducer
• ILMA- intubating LMA
• Combitube (if available)

SLCOA National Guidelines / Difficult Airway 15

 5. 4th drawer -
Pre assembled • Cricothyroidotomy equipment
invasive airway
equipment Home made - scalpal blade No20 with
handle/ tracheal dilators, ET tubes
size 4 mm internal diameter

Manufactured
4mm internal diameter

6. Surfaces of Top – fiberoptic bronchoscope/

the trolley monitor
FOB module, airway topicalisation
equipment (lignocaine spray, needles,
catheters)
Documents:
Clearly labeled difficult airway drills
displayed

GRADE X Recommended
GRADE Y Desirable
GRADE Z Optional

16 SLCOA National Guidelines / Difficult Airway

2.5 Difficult airway drills

2.5.1 Adult non-obstetric difficult airway

management drill

2.5.1.1
Unanticipated difficult laryngoscopy/intubation after
routine induction of anaesthesia

Activate PLAN A

PLAN A: Correct possible causes GRADE X

• If there is a difficulty in inserting laryngoscope, consider
and correct possible causes:

Poor head position - adjust pillows

Breast in the way - retract breast and/or use short
handle or polio blade
Use BURP (Backward, Upward, Rightward Pressure)
Relaxation sub optimal - wait

Difficult intubation:
Cormack and Lehane Grade 3 or 4 after optimal positioning,
adequate muscle relaxation and best attempt.
• Send for skilled help (nurse to phone)
• Use external laryngeal manipulation or BURP manoeuvre
(Backward, Upward and Rightward Pressure on the thyroid
cartilage)
• If grade 4 view:
– maintain oxygenation with mask ventilation with or without
an oral airway
– send a nurse to call consultant
– awaken patient

SLCOA National Guidelines / Difficult Airway 17

 • If grade 3 (only epiglottis seen)
– maintain oxygenation with mask ventilation with or without
an oral airway
– maintain anaesthesia with inhalational agent

• Use a gum elastic bougie or an alternative laryngoscope if

available

• Use of a bougie – Pass the bougie along the under surface

of the epiglottis. This technique should be practiced on a normal
airway by simulating a Grade 3 laryngoscopy view.

1. Confirm the position of the bougie:

• If the bougie is in the trachea clicks will be felt by the tip

of it hitting the tracheal cartilages.

• If no clicks, gently advance to a maximum of 45 cm. If

there is slight resistance to further advancement bougie is held
up in the bronchial tree, so proceed with intubation. Patient
may cough if not fully paralyzed which also indicates correct
placement.

2. Passing the endotracheal tube

• The tube can be either loaded on to the bougie initially or

it can be railroaded later especially if the oral cavity is small.

• Railroad the tube with laryngoscope in the mouth keeping

the larynx in view and rotating the tube 900 anticlockwise.

• If neither clicks, nor resistance nor coughing, the bougie

may be in the oesophagus, remove and reattempt, provided
saturation is above 90%.

• An additional attempt by an experienced anaesthetist can

be justified.

18 SLCOA National Guidelines / Difficult Airway

 GRADE X

PRIORITY – MAINTAIN OXYGENATION

• Send for help early
• Do not attempt laryngoscopy > 3 times
• Attempt only if an improvement on the first attempt
is made
• Stop earlier if saturation < 90%

ACTIVATE PLAN B IF FAILED TO INTUBATE

PLAN B : Use of an upper airway device which keeps the

airway open maintaining oxygenation and ventilation
while facilitating tracheal intubation Grade X

• Insert a LMA (Laryngeal Mask Airway) or intubating LMA

(ILMA) if available. Do not attempt more than twice. Cricoid
pressure may need to be reduced.
• Confirm satisfactory positioning, oxygenate and ventilate
through LMA and maintain anaesthesia.
• If satisfactory oxygenation and ventilation can be achieved
with a LMA, the decision to proceed or postpone surgery has
to be taken by the consultant anaesthetist.
• Intubation through LMA/ILMA: blind intubation may be
attempted by an experienced anaesthetist (consultant) through
an ILMA. But blind intubation through a conventional LMA
is not recommended.
• Fibreoptic intubation through LMA or ILMA has high
success rates in experienced hands.

SLCOA National Guidelines / Difficult Airway 19

 GRADE X

PRIORITY – MAINTAIN
OXYGENATION WITH A LMA
• Decision to proceed or postpone by
consultant anaesthetist
• Activate plan c if saturation < 90%
with LMA

ACTIVATE PLAN C IF FAILED TO OXYGENATE:

Saturation < 90% with 100% Oxygen via LMA/ILMA

Failed Plan A & B
PLAN C : Maintainance of oxygenation, ventilation,
postponement of surgery and awakening the patient
GRADE X

• Try to maintain oxygenation and ventilation through LMA.

• Discontinue anaesthetic gases and try to wake up the
patient.
• If oxygenation is impossible with LMA, remove and
maintain airway with oral/nasal airway and ventilate with
a facemask.
• Implement plan D immediately if ventilation is impossible
and serious hypoxaemia is developing [ Can’t Intubate,
Can’t Ventilate – CICV situation].

PRIORITY – MAINTAIN OXYGENATION

• Oxygenate and ventilate with a LMA / face
mask
• Try to awaken the patient

ACTIVATE PLAN D IF FAILED TO INTUBATE AND

VENTILATE WITH INCREASING HYPOXAEMIA

20 SLCOA National Guidelines / Difficult Airway

PLAN D : Immediate invasive life-saving interventions

GRADE X

Can’t Intubate Can’t Ventilate situation

Incidence: 0.01–2 cases per 10,000 anaesthetics.
• Immediate invasive intervention if severe hypoxaemia is
developing rapidly, especially if associated with bradycardia.
• Emergency tracheostomy is not an option in this situation.
• Options for emergency interventions:
a) Cannula cricothyroidotomy
b) Surgical cricothyroidotomy

Cannula cricothyroidotomy
• Insertion of a cannula through the cricothyroid membrane
with high pressure ventilation.
• The oxygen flush system of the anaesthetic machine and
ventilation through a 2 ml syringe connected to 4 mm ETT
connector and catheter mount does not provide sufficient
pressure for effective ventilation.

Highly dangerous in unskilled hands, therefore

not recommended

Surgical cricothyroidotomy
Low pressure ventilation can be used with this technique.

SLCOA National Guidelines / Difficult Airway 21

 CALL THE SURGEON FOR HELP

Technique
• Identify cricothyroid membrane after optimal
positioning by extending the head.
• Ask the surgeon to make a stab incision through
skin and membranes (short and rounded scalpel No 20 or
minitrach scalpel if available).
• Perform blind dissection to enlarge the incision with
scalpel handle, forceps or dilator.
• Insert a 4 mm endotracheal tube and inflate the cuff
avoiding endobronchial intubation.
• Check for correct placement and ventilate with a
breathing system/Ambu bag.
• For difficult cases eg: obese patients, use a bougie
through the incision or a tracheostomy retractor to pull
the cricoid cartilage downwards.

• Every anaesthetist should be able to perform

invasive rescue airway interventions
• Invasive airway access is a temporary
measure to restore oxygenation
• Convert to a formal tracheostomy within 24
hours

2.5.1.2
Unanticipated difficult intubation during rapid sequence
induction (RSI) in a non-obstetric patient
• These patients are at risk of vomiting or regurgitation
and subsequent pulmonary aspiration of gastric contents.
Laryngoscopy and insertion of a bougie or LMA may
prove difficult due to cricoid pressure.
• All patients undergoing RSI should be preoxygenated and
cricoid pressure applied as consciousness is lost. The
recommended force is 30 N, which should be reduced if
laryngoscopy is difficult or airway obstruction occurs.

22 SLCOA National Guidelines / Difficult Airway

 Plan of action for difficult laryngoscopy at first attempt
after RSI

ACTIVATE MODIFIED PLAN A

MODIFIED PLAN A: Correct possible causes

GRADE X
• Adjust position, technique; use BURP (backward,
upward, rightward pressure).
• If poor view: reduce cricoid force, but maintain,
use a bougie or alternative techniques if available.
• Maintain oxygenation and anaesthesia with face
mask oral/nasal airway during attempts.

PRIORITY – MAINTAIN
OXYGENATION

• Call for help early

• Do not attempt laryngoscopy > 3 times
• Maintain cricoid pressure
• Maintain oxygenation and anaesthesia
with face mask during attempts

ACTIVATE MODIFIED PLAN C IF FAILED TO INTUBATE

Main problems are risk of aspiration and spasm associated with

wearing off of suxamethonium. Therefore, in this case scenario,
if it is not emergency surgery, failure of intubation

SLCOA National Guidelines / Difficult Airway 23

 PRIORITY – MAINTAIN OXYGENATION
& AWAKEN THE PATIENT

• Oxygenate and ventilate with a LMA

• Try to awaken the patient

activates a plan of ‘wake-up’. A laryngeal mask airway

(LMA) should not be attempted at this stage.

MODIFIED PLAN C
• Maintain oxygenation and ventilation with one or two
person mask technique with or without oral/nasal
airway.
• Maintain cricoid pressure
• Postpone surgery and awaken the patient.
• If condition is immediately life-threatening continue
anaesthesia with face mask or LMA.
• Consider reducing cricoid pressure if ventilation is
difficult or insertion of LMA is difficult.

GRADE X

PRIORITY – MAINTAIN OXYGENATION & AWAKEN

THE PATIENT
• Maintain oxygenation with face mask +/- oral/nasal
airway
• Do not put the patient in lateral position
• Do not give further doses of suxamethonium
• Discontinue anaesthesia and awaken the patient

Failed oxygenation (SpO2 < 90% with 100% O2 via face

mask)

24 SLCOA National Guidelines / Difficult Airway

 • Insert a LMA if unable to maintain saturation >90%
with face mask ventilation.
• Reduce cricoid force if difficult to insert LMA.
• Discontinue anaesthesia and awaken the patient.
• If condition life-threatening discuss with the
consultant and proceed with deep inhalational
anaesthesia.

GRADE X

PRIORITY – MAINTAIN OXYGENATION &

AWAKEN THE PATIENT

• Maintain oxygenation with LMA if

oxygenation is impossible with face mask
• Reduce cricoid force during insertion of LMA
• Proceed with deep inhalational anaesthesia if
condition life-threatening

ACTIVATE PLAN D IF FAILED TO VENTILATE AND

OXYGENATE AFTER RSI (CICV situation)

PLAN D: Immediate invasive life-saving interventions

GRADE X
Surgical cricothyroidotomy
SEE above for details

SLCOA National Guidelines / Difficult Airway 25

2.5.2 Obstetric difficult airway management drill

INTRODUCTION
• Although frequency of general anaesthesia in obstetric is
declining, it still remains the single most frequent anaesthetic cause
for maternal morbidity and mortality. Hypoxic brain damage and
death due to failure of maintaining adequate oxygenation at the
time of induction and intubation are the most dreaded
complications. Anatomical and physiological changes in pregnancy
and emergency intervention in inadequately assessed patients make
the situation more challenging. The incidence of failed intubation
is almost 10 times higher in obstetric population than in the general
surgical population. Therefore regional anaesthesia should be
considered first in every case. This guideline is intended for use in
adult obstetric patient who are undergoing general anaesthesia.
This guideline is not intended for use in non-obstetric adult patients.

OBJECTIVES

• To avoid general anaesthetic related maternal morbidity

and mortality by providing definitive guidelines so that
recommended techniques will be used at every stage of general
anaesthesia.
• To assess and evaluate pregnant mothers early with regard
to anticipated difficult airway and formulate plans for intubation.

COMPETENCY/TRAINING

All qualified anaesthetists who are involved in obstetric anaesthesia

must initially complete a six month in house training in non-
obstetric rapid sequence induction and difficult airway management
and should obtain competency before embarking on general
anaesthesia in obstetrics. Training and post-training period should
include at least 10 general anaesthetics in obstetric patients under
supervision before working unsupervised.

26 SLCOA National Guidelines / Difficult Airway

2.5.2.1 Airway assessment in obstetric patients

• All obstetric patients who may require surgical intervention

must have a detailed airway evaluation in order to detect
possible difficulties and allow adequate time for planning
of technique, resources and expert/senior help.
• Use the following tools collectively in addition to airway
history:
Mallampati score
Thyromental distance
Mouth opening
Neck mobility
Facial oedema- especially in PET
Because of poor predictive value, anesthetists should not
completely rely on one or two airway assessment tools.
• Explain the procedure and risks/benefits and obtain
informed consent for general anaesthesia.
• All mothers predicted to have a high risk of airway
problems and needing elective surgical intervention should
be evaluated by a consultant anaesthetist in advance.
• Adequate training should be provided to all anaesthetists
to manage a difficult obstetric airway. All theatre personnel
and obstetric teams must be educated regarding this
anaesthetic complication to obtain all possible help in the
event of an emergency.
• All obstetric theatre suites should be equipped with a
difficult airway trolley See: Difficult intubation trolley
in the previous guideline.
• The suggested algorithm should be followed in the event
of unanticipated difficult airway. Adherence to a specific
algorithm avoids/minimizes confusion regarding possible
next safe step during crisis and improves out come of the
patient.

SLCOA National Guidelines / Difficult Airway 27

 Procedure for Rapid sequence induction in an obstetric
patient

• Ensure availability of cross-matched blood and

provision of acid prophylaxis.
• Ensure wide bore i.v. access, preferably 14G or 16G
• Establish full monitoring (ECG, Pulseoxymetry,
NIBP, Capnography)
• Make sure mother is in optimum intubation position,
which includes placing one or two pillows under
her head with 15 degree left lateral tilt to avoid
aorto-caval compression.
• Method of induction must be rapid sequence
irrespective of fasting status of the mother.
• Ensure adequate preoxygenation (breathing100%
oxygen through breathing attachment/circuit with
good sealed mask for 3-5 minute or 3 good vital
capacity breaths.) before intravenous induction.

• Apply and maintain cricoid pressure with loss of

eyelid reflex and administer suxamethonium.
Attempt insertion of laryngoscope once full muscle
relaxation is established.
• Visualize glottis following successful laryngoscopy
and insert the endotracheal tube and confirm with
capnography. Make sure both lungs are being
ventilated equally with chest expansion and
auscultation and then secure the tube.

28 SLCOA National Guidelines / Difficult Airway

2.5.2.1 Unanticipated difficult laryngoscopy/
intubation after rapid sequence induction in an
obstetric patient

ACTIVATE MODIFIED PLAN A

MODIFIED PLAN A GRADE X

• If there is a difficulty in inserting laryngoscope,
consider following possibilities and apply suggested
corrective measures:
Poor head position - adjust pillows
Breast in the way - retract breast and/or use
short handle or polio blade
Cricoid hand in the way - reposition but maintain,
use BURP (Backward, Upward, Rightward Pressure)
Relaxation sub optimal - wait
Muscle rigidity or anatomical abnormality -
abandon procedure and call for help

• Consider use of gum-elastic bougie and/or McCoy

blade to intubate if the glottic view is either Lehane-
cormack grade II or III. Follow steps in the previous
section regarding the use of bougie.

Failed intubation / Lehane- Cormack Grade 4

following RSI in an obstetric patient (Failed plan A)

The mother is at risk of aspiration of gastric contents and

airway spasm can occur due to wearing off of
suxamethonium. Therefore, a plan of ‘wake-up’ should
be activated unless there is an immediate life-threatening
condition with need to continue surgery.

SLCOA National Guidelines / Difficult Airway 29

 ACTIVATE MODIFIED PLAN C (FAILED
INTUBATION DRILL)

MODIFIED PLAN C

• Do not panic.
• Call for senior help. Send somebody other than the
involved anaesthetist.
• Maintain oxygenation with 100% oxygen and cricoid
pressure with one or two person mask technique with
or without oral /nasal airway. Provision of adequate
oxygenation must be the priority at this stage.

• Attempt gentle positive pressure ventilation while

maintaining cricoid pressure to provide/maintain
oxygenation and to protect airway.
• Do not repeatedly attempt to insert laryngoscope or to
visualize glottis.
• Do not give second dose of suxamethonium.
• Do not turn the mother to a side as this makes
maintenance of airway and oxygenation more difficult.
But maintain the left lateral tilt.
• If adequate positive pressure ventilation is possible, and
oxygenation is adequate (SpO 2 >93% ) determine
whether there is urgency/need to proceed with the
planned operation.
• If surgery is not life-saving, awaken the patient:

Discontinue inhalation agent, maintain airway with

100% oxygen until patient is awake.
Turn to lateral position once awake.
Decision to proceed with surgery at this stage using
spinal/epidural or CSE should be made after
discussing with the consultant anaesthetist.
GRADE X
If regional anaesthesia is contra-indicated consider
local infiltration anaesthesia by the surgeon.

30 SLCOA National Guidelines / Difficult Airway

 The degree of anaesthesia and analgesia may be sub
optimal and therefore mother should be fully informed
about the technique. GRADE X

If regional techniques are not indicated, awake fiber-optic

intubation followed by general anaesthesia may be
considered when facilities and expertise is available.
GRADE Y

• If surgery is life-saving, continue anaesthesia with

SPONTANEOUSLY BREATHING TECHNIQUE:

Deepen anaesthesia with inhalational agent in 100%

oxygen while allowing the mother to breathe
spontaneously.
Maintain airway with existing method. Maintain
saturation > 93%.
Provide adequate analgesia /hypnosis / amnesia once the
baby is born. Consider fentanyl, alfentanil, midazolam,
propofol.
Start an infusion of syntocinon to overcome uterine
relaxation caused by high dose of inhalational agents.

FAILED OXYGENATION (SpO2 < 90%) VIA FACE

MASK.
Maintain tight seal with face mask and apply oxygen
with closed breathing system valve.
Ease cricoid pressure to allow adequate ventilation. If
the ventilation is possible without cricoid pressure,
allow the patient to wake up if surgery is not life-saving.
If operation is life-saving consider spontaneous
breathing technique as above.
Insert a laryngeal mask airway (LMA) if ventilation is
difficult / impossible even without cricoid pressure.
If ventilation is possible with the laryngeal mask
airway, consider waking up or continuing deep
anaesthesia depending on the urgency as above.

SLCOA National Guidelines / Difficult Airway 31

 ACTIVATE PLAN D IF VENTILATION IS
IMPOSSIBLE AND SATURATION IS < 90%

PLAN D: Immediate invasive life-saving interventions

to rescue the mother
GRADE X
a) Cannula cricothyroidotomy
b) Surgical cricothyroidotomy

SEE Page 20 for details

MATERNAL CARDIAC ARREST

Perform Caesarean section and deliver the baby as soon

as possible.
CPR will be otherwise unsuccessful as the gravid uterus
impedes the cardiac output.

• In each successfully managed difficult airway

situation, recovery should be very cautious as premature
extubation could lead to serious complications again.

2.5.3 Management of acute upper airway

obstruction

2.5.3.1 Introduction
Obstruction of the airway occurs quite commonly in association
with general anaesthesia. The anaesthetist is often called to stabilize
and intubate patients who present with acute airway obstruction in
the ETU/ICU or ward set up.
Airway management is a fundamental anaesthetic responsibility
and skill. Airway obstruction demands a rapid and organised
approach to its diagnosis and management and undue delay usually
results in desaturation and a potential threat to life.
32 SLCOA National Guidelines / Difficult Airway
An uncomplicated pre-learned sequence of airway rescue
instructions is an essential part of every anaesthetist’s clinical
practice requirements.

2.5.3.2 Definition
It is a potentially life-threatening event caused by a blockage of
the upper airway, which can be in the trachea, larynx or oropharynx.

2.5.3.3 Common causes

1. Upper airway
• Oropharyngeal : tumours, haematoma, infection (epiglottitis,
croup), foreign bodies, sleep apnoea, obesity, facial oedema,
burns
• Lesions in and around the larynx : malignancy, infections,
laryngospasm, laryngeal oedema, inhalational injury

2. Mid-tracheal obstruction
• Retrosternal goitre
• Tracheal stenosis

3. Lower tracheal and bronchial obstruction

• Tumours

2.5.3.4 Presentation

2.5.3.4 a) Partial airway obstruction-

• Stridor-
Inspiratory –obstruction at or above upper trachea
Expiratory - obstruction of the lower trachea or
bronchi.
• Increased work of breathing –suprasternal, intercostal and
subcostal retraction along with an increased use of accessory
muscles of respiration. Paradoxical ‘see-saw’ movement of
abdomen and chest.

SLCOA National Guidelines / Difficult Airway 33

 • Choking – sudden onset associated with coughing and
aphonia indicates foreign body inhalation.
• Wheezing
• Agitation, panic, changes in consciousness or
unconsciousness
• Desaturation, hypercapnia

2.5.3.4 b) Complete airway obstruction-

• Cyanosis
• Inability to speak or breathe
• Severe desaturation associated with bradycardia,
cardio-respiratory arrest

2.5.3.4 c) Upper Airway Obstruction under anaesthesia-

Breathing spontaneously:
• Poor movement of the reservoir bag with or
without above signs
On IPPV :
• Increased airway pressure with decreased chest movement
• Noisy respiration
• Wheezing

2.5.3.5 Management
2.5.3.5 a) Life threatening upper airway obstruction in the
ETU/ICU/Ward
- Send for senior help; ask a nurse to phone.
- Do not disturb the patient or delay for investigations, i.v. cannulation
etc.
- Do not change the patient’s preferred position.
- Administer 100% humidified O2 via facemask, attach pulse oximeter.
- Nebulized adrenaline 1: 1000 5mg (400 mcg/kg up to a maximum of
5mg for children)
- Take the patient to the theatre. Induce anaesthesia with halothane or
sevoflurane in oxygen and intubate with a small ETT. Have the ENT
surgeon ready to intervene if necessary (tracheostomy or rigid
ventilating broncoscopy)
- Do not give i.v. induction agents, sedatives or muscle relaxants before
intubation as these may lead to catastrophic CICV (Can’t Intubate
Can’t Ventilate) situation.

34 SLCOA National Guidelines / Difficult Airway

 2.5.3.5 b) Options for immediately life threatening
events and senior help not available

Severe cases: Perform cricothyroidotomy or tracheotomy

under local anaesthesia if intubation is not possible.
Less severe cases: Perform intubation or tracheostomy
under deep inhalational anaesthesia with face mask or LMA
if not improving with nebulized adrenaline.
Children and uncooperative patients: Administer deep
inhalational anaesthesia with preservation of spontaneous
breathing. Apply a moderate degree of CPAP which is
effective at keeping the airway open. Local anaesthetic spray
to the larynx may be helpful once the patient is deep and
stable and give atropine to prevent bradycardia in children.

2.5.3.5 c) Acute upper airway obstruction under anaesthesia

Laryngospasm : Acute glottic closure by the vocal cords

This is a common cause for acute airway obstruction in the peri-
operative period.
It is a potentially life-threatening condition which, if poorly
managed can cause severe hypoxaemia, pulmonary aspiration and
post-obstructive negative pressure pulmonary oedema.

Causes
Surgical stimulation or airway instrumentation or
removal under light anaesthesia
Regurgitation, vomiting or aspiration
Blood or secretions in the pharynx
Irritant volatile agent and exacerbation of a soiled
airway
Children are more prone to laryngospasm and become
cyanosed more rapidly than adults. Hypoxia associated
with severe bradycardia is a preterminal event in them.

SLCOA National Guidelines / Difficult Airway 35

 Presentation
Inspiratory stridor/airway obstruction/absent
inspiratory sounds if complete obstruction.
Increased respiratory efforts, tracheal tug
Paradoxical chest/abdomen (“see-saw) movements
Desaturation, bradycardia, central cyanosis

Immediate management
Call for help
Stop stimulation
Remove oral airway/LMA if cause for laryngospasm
Clear the airway
Open the airway (head tilt, chin lift and jaw thrust)
Give 100% oxygen (with inhalational agent if
appropriate)
Deepen anaesthesia if appropriate (propofol 1-2 mg/
kg iv bolus) or allow to wake up
Insert oral /nasal airway if depth of anaesthesia
adequate
Apply CPAP (close the expiratory valve and maintain
a tight seal by holding the mask with two hands) and
gently ventilate while looking for a cause
If all above measures fail give suxamethonium 0.25 -
0.5 mg/kg IV or 2-4 mg/kg IM if access is not
available. Use early in complete airway obstruction
as IPPV exacerbates the condition by inflating the
stomach and forces the arytenoids and false cords
against the true vocal cords. Give atropine 10mcg/kg
for children or if associated with bradycardia.
Intubate and ventilate if necessary

Subsequent management
Monitor in the recovery until stable, or in a HDU
or ICU depending on the condition
Exclude pulmonary aspiration, negative pressure
pulmonary oedema
Explain what happened and reassure the patient as
awareness is possible.

36 SLCOA National Guidelines / Difficult Airway

2.5.4 Management of Desaturation under anaesthesia

2.5.4.1 Introduction
Desaturation under anaesthesia (SpO2 < 93%) is a
potentially life-threatening event that can result from many
causes. Inability to recognize the cause and manage it
promptly may lead to hypoxic brain injury or death.
Correct use of a structured drill has been shown to identify
99% of possible causes for desaturation within 40-60
seconds.
Persistent desaturation should be managed with hand
ventilation using 100% oxygen, return to a supine position
and completion of a checklist of possible causes (COVER-
ABCD). Blood gases, chest X-ray and bronchoscopy may
be required if no apparent cause can be found.

2.5.4.2 Causes for desaturation under anaesthesia:

I Equipment problems

a) Anaesthetic machine – related :

Hypoxic gas mixture
Anaesthetic machine error
No gas flow during preoxygenation
Disconnection, leaks,
Breathing system : damage to inner tube in Bain
system, obstruction of tubings, catheter mount,
connectors, filter
Monitor error
b) Endotracheal tube –related:
Leaks, kinking, obstruction
Misplacement- oesophageal, endobronchial,
accidental extubation
Failed intubation / failed ventilation

SLCOA National Guidelines / Difficult Airway 37

 II Patient problems

a) Airway - obstruction if unintubated- secretions,

blood or debris, gastric contents, foreign body,
laryngospasm
b) Breathing – hypoventilation, bronchospasm, lobar
collapse, pneumo- or haemothorax, gaseous
distension of the abdomen (esp. in infants)
c) Circulation – cardiac arrest, haemodynamic
instability, congestive cardiac failure with pulmonary
oedema, obstruction to circulation from excessive
intrathoracic pressure(inadvertent PEEP), pulmonary
embolism, cardiac tamponade, reversal of a shunt
d) Other – worsening of pre-existing conditions,
obesity, sepsis
e) Drugs – anaphylaxis, malignant hyperpyrexia

2.5.4.3 Desaturation drill

• Confirm diagnosis: check pulse oximeter waveform
• Exclude cardiac arrest
• Call for help
• Administer 100% oxygen and hand ventilate
• Complete “COVER ABCD” algorithm if intubated or
“AB COVER CD” if breathing spontaneously to
identify the cause for desaturation.

“COVER ABCD”

C1 Circulation
Check rate, rhythm and volume of the central pulse.
Check ETCO2 which indicates cardiac output.
Initiate CPR if no central pulse.

38 SLCOA National Guidelines / Difficult Airway

C2 Colour
Give 100% oxygen; ensure that only oxygen flow
meter is operating. Look for central cyanosis. Check
pulse oxymeter.

O1 Oxygen
Check flow meter settings to ensure that mixture is
not hypoxic.

O 2 Oxygen analyzer
Check that the oxygen analyser shows a rising oxygen
concentration distal to the common gas outlet.

V1 Ventilation
Ventilate the lungs by hand to assess breathing circuit
integrity, check the patency of the catheter mount,
connector and filter*, airway patency, chest
compliance and air entry by “feel” and careful
observation and auscultation.
Also inspect capnography trace.

V2 Vaporiser
Note settings and levels of agents. Check all vaporiser
filler ports, seatings and connections for liquid or gas
leaks during pressurisation of the system.
Consider the possibility of the wrong agent being in
the vaporiser.

E1 Endotracheal tube
Systematically check the endotracheal tube (if in use).
Ensure that it is patent with no leaks or kinks or
obstructions.
Check capnograph for tracheal placement and oximeter
for possible endobronchial position.
If necessary, adjust, deflate cuff, pass a catheter, or
remove and replace.
SLCOA National Guidelines / Difficult Airway 39
 E2 Elimination

Eliminate the anaesthetic machine and ventilate with self-

inflating (e.g. Ambu) bag with 100% oxygen (from alternative
source if necessary).
Retain gas monitor sampling port if available (but be aware of
possible problems).

R1 Review monitors
Review all monitors in use (preferably oxygen analyser,
capnograph, oximeter, blood pressure, electrocardiograph (ECG),
temperature and neuromuscular junction monitor). For proper use,
the algorithm requires all monitors to have been correctly sited,
checked and calibrated.

R2 Review equipment
Review all other equipment in contact with or relevant to the
patient (e.g. diathermy, humidifiers, heating blankets, endoscopes,
probes, prostheses, retractors and other appliances).

A Airway
Check patency of the unintubated airway.
Consider laryngospasm or presence of foreign body, blood,
gastric contents, nasopharyngeal or bronchial secretions.
Mucus plugs or bronchial secretions can causes marked
desaturation especially in young children.

B Breathing
Assess pattern, adequacy and distribution of ventilation.

Consider, examine and auscultate for bronchospasm,

pulmonary oedema, lobar collapse, pneumo- or haemothorax
and impaired ventilation due to retractors.

40 SLCOA National Guidelines / Difficult Airway

 C Circulation
Repeat evaluation of peripheral perfusion, pulse, blood
pressure, ECG and filling pressures (where possible) and
hypovolaemia or any possible obstruction to venous return such
as embolism, raised intrathoracic pressure (e.g. inadvertent PEEP),
sepsis, myocardial depression and poor cardiac output or direct
interference to (e.g. stimulation by central line) or tamponade of
the heart.

Note any trends on records.

D Drugs

Review intended (and consider possible unintended) drug or

substance administration.

Consider whether the problem may be due to unexpected

effect (anaphylaxis, malignant hyperpyrexia), a failure of
administration or wrong dose, route or manner of administration
of an intended or “wrong drug”.

Review all possible routes of drug administration.

2.6 Extubation & Follow up

When the airway has proved difficult to manage a difficult airway
follow-up should be initiated in the postoperative period.

2.6.1 Strategy for Extubation of the Difficult Airway

The strategy should depend on the surgery, the condition of the
patient, and the skills and preferences of the anaesthetist.

Take the following into consideration before extubation:

GRADE X
SLCOA National Guidelines / Difficult Airway 41
 1. Risks and benefits of awake extubation versus deep
extubation with the use of a nasopharyngeal airway or LMA.

2. Extubate with the expiratory valve tightly closed to produce

a cough.

3. Presence of any general clinical factors that may impair

ventilation after extubation.

4. Short-term use of a device that can serve as a guide for

reintubation if necessary. Eg : Cook airway exchanger – it is
usually inserted through the lumen of the tracheal tube and
into the trachea before the tracheal tube is removed. It is
rigid to facilitate intubation and hollow to facilitate
ventilation and administer oxygen.

5. Give prophylactic dexamethasone if there is a risk of

laryngeal oedema and monitor closely in the post-operative
period.

2.6.2 Follow-up Care GRADE X

Document the presence and nature of the airway difficulty

and management strategy in the anaesthetic record.

Explain to the patient or responsible person the difficulty,

and the importance of informing the next anaesthetist of the
problem.

Evaluate and follow up complications of difficult airway

management: sore throat, difficulty in swallowing, pain or
swelling of the face, bleeding, tracheal and esophageal
perforation, chest pain, pneumothorax, aspiration, and dental
damage. ENT referral if necessary. Express regret for
morbidity.

42 SLCOA National Guidelines / Difficult Airway

 2.6.3 COMPLETE A DIAGNOSIS CARD AND
HAND OVER TO THE PATIENT- this is a useful way of
making certain that you have documented events properly.

Equipment used:
Other information:
Reasons/comments
Difficult mask Is awake Yes
intubation
/ necessary in the future?
ventilation? Complications
No :
Difficult direct Yes /
laryngoscopy? No
Name of anaesthetist:
Difficult YES /
tracheal intubation? Grade: NO Date:
Laryngoscopy grade If
1 / you
2 / 3 /require
4 further information please contact the
Anaesthetic Department.

SLCOA National Guidelines / Difficult Airway 43

 References
1. Management of difficult and failed intubation in obstetrics-
BJA/CPDE, vol1, No4, 2004

2. Airway management in obstetrics. - Indian J Anesth 2005;

49(4): 325-338

3. Difficult airway society guidelines for management of

unanticipated difficult intubation –Anaesthsia
2004,53,p675-694

4. Hand Book of Anaesthesia 3rd Edition 2004

5. American Society of Anesthesiologists Task Force on

Management of the Difficult Airway. Practice guidelines
for management of the difficult airway: an updated report
by the American Society of Anesthesiologists Task Force
on Management of the Difficult Airway.
Anesthesiology 2003 May;98(5):1269-77.

6. Prediction and Management of Difficult Tracheal

Intubation. Update in Anaesthesia WFSA Issue 9 (1998)
Article 9: Page 2 of 4

44 SLCOA National Guidelines / Difficult Airway