Airway Assessmentby

Dr (Mrs) Abikoye, feb.4, 2013

Outline• Introduction• Definition• Importance of Airway to Anaesthetist

• Causes of Airway Compromise• Airway Assessment• History• Examination

• Predictive Airways Tests

• Special considerations in Pediatrics and Diabetes Mellitus• Investigations• Acronyms

• Conclusions / Recommendations

Introduction

• Airway • In its day-to- day use usually refers to the upper airway

which may be defined as the extra-pulmonary air passage consisting of the nasal and oral cavities, pharynx, larynx, trachea and large bronchi.

• Evaluation of the airway is done in accident and emergency room, intensive care unit, during pre-anaesthesia visit, on the wards or in designated difficult airway clinics.

• Airway assessment predicts the ease of ventilation either with facemask, tracheal intubation or both.

• A number of intraoperative anesthetic complications resulting in patient morbidity and mortality has been attributed to ill judgement and insufficient evaluation of airway.

Anatomy of upper airway

Definitions by the ASA Difficult Airway

The clinical situation in which a conventionally-trained anaesthetist experiences difficulty with mask ventilation, tracheal intubation or both.

Difficult VentilationThe inability of a trained anaesthetist to maintain the oxygen saturation >90% using a facemask for ventilation and 100% inspired oxygen, provided that the pre-ventilation oxygen saturation level was within the normal range.

Difficult Intubation• More than 3 attempts• Longer than 10 minutes• Failure of optimal best attempt

Conditions causing airway compromise

ACQUIRED Trauma• Facial Injuries - hematoma , unstable fracture of maxilla and mandible.• C-spine injuries• Laryngeal/tracheal trauma

• Acute burns• -oedema of airway Neoplasm -cystic hygroma , adenoma ,goitre , nasopharyngeal and laryngeal tumours , nasal tumours. - stenosis or distortion of the airway ,fixation of larynx or adjascent tissues due to infilteration or fibrosis from radiation Obesity - short thick neck, redundant tissue in the airway , sleep apnea Acromegaly- Macroglossia , prognath

Conditions causing airway compromise

Causes of airway compromise contd Infections• Supraglottis , croup -laryngeal oedema,hyperactive airway• Abscesses e . g intraoral, retropharyngeal -cause distortion of airway • Ludwig angina -cause distortion of airway Arthritis• Rheumatoid arthritis - temporomandibular joint ankylosis ,cricoarythenoid arthritis, restricted mobility of cervical spine Ankylosing spondylitis - ankylosis of cervical spine ,TMJ , lack of mobility of cervical spine Pregnancy -upper airway oedema,breast enlargement,weight gain,upward displacement of diaphragm

Assessment History will include but not limited to the following:

• Review old records whenever possible e.g. history of difficult

airway and interventions.• Hoarseness of the voice• Presence of dental bridges, caps, fillings, dentures, loose teeth. • Snoring, obstructive sleep apnoea syndrome, nasal blockage• Catarrh, cough, wheezing, asthma, COPD, smoking. • Joint diseases like osteo-arthritis, rheumatoid arthritis,

ankylosing spondylitis and other connective tissue disorders affecting temporo-mandibular and atlanto-occipital joints.

• Bleeding abnormalities especially before nasal intubation. • Diabetes Mellitus

Physical Examination• General Examination• Airway Examination• Systemic Examination

General Examination

• Level of consciousness• Abnormal facie (pointer to congenital abnormalities

or malformations)• Body Mass Index >26kg/m²• Respiratory distress • Presence or absence of cyanosis• Pregnancy

Airway Examination

• Outline• Head• Neck• Mouth• Predictive Airway Tests

Airway Examination (contd.)

• Face and Head• Facial features may suggest a syndrome or disease state

e.g. Downs syndrome, Pierre-Robin syndrome, acromegaly, hydrocepahlus

• long face, prognatism, retrognatism • Contractures from burns injury, surgery or radiotherapy• Facial tumours e.g. maxillary, mandibular, parotid,

Burkitt’s , Ludwig’s angina.• Facial injuries evidenced by oedema, hematoma,• Unstable jaw(as in jaw fracture)• Beards and moustaches• Hair dos and attachments (occipital hump)• Cosmetic attachments nose-piercing, tongue piercing

Airway Examination (contd.)

• Neck • Short in some congenital abnormalities e.g Kippel-

Feil syndrome and Down’s syndrome• Short thick neck in obese• Swellings –goitre, cystic hygroma, Ludwid’s angina,

oedema, subcutaneuos emphysema. • Contractures post burns or radiotherapy• Surgical scars e.g. previous tracheostomy scar

Mouth Mouth opening.

• Normal should admit 3 fingers of the patient vertically in the midline or inter-incisors gap >4cm.

• limited in temporo-mandibular joint disease, masseter spasms, contracture from burns injury

Teeth• Arrangement: normal or anarchy as in oral tumours and Burkitt’s

lymphoma• Prominent upper incisors, protruding teeth(buck)• Edentulous (problem of mask seal during bag mask ventilation because of

distortion of the contours of the face.• Gaps in between teeth• Missing tooth

Palate• High arched palate or a long narrow mouth may present difficulty.

Mouth (contd.)

Tongue• Enlarged in tumours, oedema following injury, congenital

malformation with macroglossia e.g Down’s syndrome, acromegaly

• Cosmetic; Tongue-splitting, tongue rings, studs etc. Tonsils and adenoids• Enlarged in children• Snoring and sleep apnea• Bleeding during nasal intubation• Careful intubation to avoid tonsilar bleeding

Pharynx• Tumours and masses, secretions, blood, foreign bodies,

false membrane in diphtheria, retro-pharyngeal abscess, acute epiglottitis.

Predictive Airway Tests• These are tests done to predict the ease of face

mask ventilation and intubation.1. Inter-incisor Distance2. Mallampati Test3. Mandibular protrusion Test4. Mandibulo-Hyoid Distance5. Thyromental Distance, Patil’s Test6. Sternomental Distance7. Atlanto-occipital Joint Extension8. Prayer Sign9. Palm Print Test10. Comark and Lehane Test

Inter-incisors distance• It’s a test of temporo-mandibular joint (TMJ)

mobility.• Measures the distance between the upper and

lower incisors.• 3 finger breadths of patient is placed vertically in

the mouth in the midline.• Normal->4cm(40-60mm) or 3 finger breadth. If

less than 30mm,indicates TMJ dysfunction, and patient with less than 25mm is likely to have difficult laryngoscopy.

Mallampati Test• Designed by S. Rao Mallampati an indian- born

Boston anaesthetist.• Classification was modified by Samson and

Young in 1987. • Further evaluated by Tham who discovered

through his study that phonation produced marked improvement of view and a more favourable classification.

Mallampati Test (contd.) • Access the size of the tongue to pharyngeal size.• Its performed with the patient sitting up, head in

neutral position, looking straight ahead with anaesthetist at the same level with patient.

• The mouth is wide open with the tongue protruding to its maximum without phonating.

• Classification is based on the extent to which the base of the tongue is able to mask the visibility of pharyngeal structures.

Mallampati classification

Mallampati Original• Class 1-visualisation of the soft palate, fauces ,uvula, anterior

and posterior pillars • Class 2-visualisation of the soft palate, fauces and uvula• Class 3-visualisation of soft palate and base of uvula

Modified• By Samson and Young in 1987• Class 4-only the hard palate is visible• Classes 3 and 4 are predictive of difficult intubation

Mandibular Protrusion Test• Assess temporo-mandibular joint function• Patient is told to advance the mandible as far as

possible.1. Class A- lower incisors can be protruded beyond

the upper incisors2. Class B- the lower incisors can only be advanced to

the level of upper incisors.3. Class C- lower incisors cannot reach the level of

upper incisors• Classes B and C predicts difficult mask

ventilation and tracheal intubation

Mandibulo-hyoid distance

• Measures the mandibular length from the chin to the hyoid bone.

• Distance should be at least 4cm or 3 fingers breadth.

Thyro-mental Distance(Patil’s test)• It measures mandibular space.• Defined as the distance from the mentum to the

thyroid notch while the patient’s neck is is fully extended.

• Helps in determining how readily the laryngeal axis will fall in line with the pharyngeal axis when atlanto-occipital joint is extended.

• Greater than 6cm is normal in adult, less than 6cm or 3 finger breadth predicts difficulty.

• Positive in patients with short mandible, protruding upper incisors, reduced intra and submandibular space.

Diagram of thyromental distance

Sterno-mental distance• Proposed by Sauva in 1948• Also a measure of mandibular space• Estimation of the distance from the suprasternal

notch to the mentum with the head fully extended on the neck and the mouth closed.

• Normal is 12.5cm. Less than this predicts difficult intubation.

Sternomental distance

Atlanto –occipital joint extension• Assess the ease to assume a sniffing or Magil’s

position for intubation i.e. alignment of oral, pharyngeal and laryngeal axes in an arbitrary straight line.

• Patient holds the head erect, looking straight ahead and he is asked to maximally extend the head.

• Grade 1- > 35 degrees (normal)• Grade 2- 22-34 degrees• Grade 3- 12-21 degrees• Grade 4- < 12 degrees

Atlanto-axial joint extension

Airway Assessment in Diabetes Mellitus

• Diabetics have limited joint mobility due to glycosylation of tissue proteins and collagen.

• The same process affect the spine, temporo-mandibular joint and larynx.

• Incidence is about 30-40% in IDDM• Two tests are used• Palm print• Prayer sign

• The two tests have higher sensitivity for diabetics

Prayer Sign• Patient is asked to bring both palms together.• Its categorized as follows;

Positive-when there is a gap between the palms Negative-when there is no gap.

Palm Print• Patient is made to sit. • Palms and fingers are painted with ink.• Patient presses hand firmly against a white

paper placed on a hard surface.• Grade 0-All the phalangeal areas are seen• Grade 1-Deficiency in the inter-phalangeal areas

of the 4th& 5th digits• Grade 2-Deficiency in inter-phalangeal areas of

2nd-5th digits• Grade 3-only the tips of the digits are seen

Airway Assessment in PaediatricsFactors responsible for difficult airway • Large head and tongue• Narrow nasal passages• Anterior and proximal larynx• Long epiglottis• Short trachea and neck• Prominent adenoids and tonsils• Teeth eruption• Loose tooth

Laryngoscopy Indirect• Usually done otolaryngologists• Visualising the larynx through a series of mirrors

and head lamp• Detects vocal cord paralysis, masses and other

lesions Direct• Conventional• Cormack-Lehane Grading of View on laryngoscopy

• Rigid• Fibreoptic

Cormack-Lehane Classification

• Its used to describe laryngeal view on direct visualization at conventional laryngoscope.

• Class 1- most of the glottis is visible• Class 2- only the posterior glottis is visible• Class 3- only the epiglottis is visible• Class 4- the epiglottis is not seen

Limitations-• Inadequate knowledge of the grading system– Poor intra-observer and fair inter-observer reliability– Validity questioned

Mallampati and Comack-Lehane classification

Investigations• Radiological• Plain radiographs of neck , thoracic inlet and chest

(AP and lateral)• Mandibulo-hyoid distance• Atlanto-occipital gap• Anterioir/posterioir depth of mandible• Cervical ribs• Abnormal curvature of cervical spine

• Fluoroscopy for dynamic imaging• Cord mobility• Airway malacia• Emphysema

Investigations (contd.)• Ultrasonography• Mediastinal mass, lyphadenopathy, cyst, abscess etc

• Computerized Tomography• Magnetic Resonance Imaging

Acronyms LEMON Airway Assessment OBESE Uses• For rapid assessment in emergency situations

Acronyms LEMON Airway Assessment L- Look externally(facial trauma,large incisors,beard/moustache,large tongue). E- Evaluate the 3-3-2 rule(incisors distance-3 finger breadth,hyoidmental distance-3 finger breadth,thyromental distance-2 finger breadths. M-Mallam Patti(score 0f 3 and above) O- Obstruction (conditions like epiglottitis,peritonsillar abcess,trauma) N-Neck mobility( limited neck mobility)

maximum score of 10 with 1 point for each criteria

Predictors of face mask ventilation

O-the Obese(body mass index >26kg/m2)B- BeardedE- the Elderly(older than 55yrs)S- the SnorersE- the Edentulous

Conclusion

• Airway assessment helps to identify patients with difficult airway or those with potential airway problems and to decide on the appropriate method of ventilation.

• This will help to reduce complications occuring due to airway problems.

Thank you for

listening