managing the difficult airway

by DR. BERNARD FIIFI BRAKATU

DIFFICULT AIRWAY- ASSESSMENT AND

MANAGEMENT

INTRODUCTIONRELEVANT ANATOMYASSESSMENT OF THE AIRWAYMANAGEMENT

OUTLINE

Clinical situation in which a conventionally trained anesthesiologist experiences difficulty with face mask ventilation of the upper airway, difficulty with tracheal intubation, or both.

(Practice Guidelines for Management of the Difficult Airway; Anesthesiology 2003; 98: 1269)

It represents a complex interaction between patient factors, the clinical setting and the skills of the practitioner

INTRODUCTION-What is “difficult airway”?

Explicit descriptions that can be categorized or expressed as numerical values are encouraged and includes(but not limited to):

1. Difficult face mask ventilation – a)inadequate mask seal, excessive gas leak or

excessive resistance to the ingress or egress of gasb) Signs of inadequate face mask ventilation – absent

or poor chest movement, absent or inadequate breath sounds, auscultatory signs or severe obstruction, cyanosis, gastric air entry or dilatation, decreasing or inadequate SpO2, absent or inadequate exhaled CO2, absent or inadequate spirometric measures of exhaled gas flow, hemodynamic changes associated with hypoxemia or hypercarbia(e.g. hypertension, tachycardia, arrhythmia).

Descriptions…

2. Difficult laryngoscopy – inability to visualize any portion of the vocal cords after multiple attempts at conventional laryngoscopy

3. Difficult/failed tracheal intubation – requiring multiple attempts, in the presence or absence of tracheal pathology

Death!!Brain injuryCardiopulmonary arrestUnnecessary tracheostomyAirway traumaDamage to teeth

Possible adverse outcome

Anatomy

April 11, 2023 7

Anatomy-Pediatric nuancesLarge tongue short neck(esp neonate)Larynx is cephaladNarrower cricoid cartilageEpiglottis is U-shaped and stiffGlottic opening is anterior in a neonate

Results in difficulty in aligning the oral, pharyngeal and glottic axes and elevation of epiglottis for full exposure of glottic opening thus resistance to passage of tubes through the glottic opening.

Comprehensive history and physical exam

HISTORY- identify risk group and risk factors for the patient- PMH and past surgical hxCheck records on previous anesthesia if available

PHYSICAL EXAMINATION-General exam- note hoarseness, stridor or prev

tracheostomy scar suggests possible tracheal stenosis -Systemic examination

ASSESSMENT

Inspect from both ant and lat views – facial features for bony and soft tissue abnormalities, receding chin, mandibular and maxillary fractures

MOUTH OPENING – Score acc to Mallampati’s classification Check for: TMJ mobility –space btn mandibular condyle and tragus shd admit

one finger Aperture btn incisors shd admit 2 fingers -intra-oral tumors -dentition- loose teeth, prostheses, dental abnormalities Can patient protrude the tongue maximally?

NECK -Inspect for neck swellings, tracheal deviation and scarring -Check for full flexion, extension, rotation and the thyromental

distance on full extension(difficulty if <6.5cm or 3fingerbreadths)

P.E

Recent Imaging studies eg CT or MRI scans may help define difficult anatomy and guide mngt

**Occipito-atlanto-axial disease(R/O in RA or ankylosing spondylitis) is more predictive of difficult laryngoscopy than disease below C2

**Plain Lateral X-rays may show flexion/extension deformities and subluxation

Investigations

PATIENTS WITH POTENTIALLY DIFFICULT AIRWAYAnatomical anomalies eg. Micrognathia(Pierre-

Robbin’s), Macroglossia(Down’s, acromegaly, congenital hypothyrodism, amyloidosis), Burns and contractures involving head and neck

Obese patients – shorter neck and reduced motion at C-spine

Pregnant patients – ecclampsia(laryngeal edema)Upper airway obstruction- tumors, infections,

maxillofacial trauma, large goiterC-spine pathologies-fracture, subluxation/dislocation,

Rheumatoid arthritis, ankylosing spondylitisPMH of difficult intubation during prev anaesthesia

MALLAMPATI’S CLASSIFICATIONCORMACK AND LEHANE CLASSIFICATION

CLASSIFICATION

Done during pre-op assessmentPredicts difficulty of intubationPatient sits up with Anesthetist at eye level,

opens mouth as wide as possible and protrudes the tongue

Pharyngeal structures are identical w/o the pt phonating

Results influenced by ability to open the mouth, sizee and mobility of tongue and other intra-oral structures

MALLAMPATI’S CLASSIFICATION

Class 1: Full visibility of tonsils, uvula, and soft palate

Class 2 Visibility of hard and soft palate and, upper portion of tonsils and uvula

Class 3: Visibility of soft and hard palate and base of the uvula

Class 4: Visibility of only hard palate

Schema

…putting it togetherGrade 1 or 2 predicts an easier intubation

Grade 3 or 4 predicts a more difficult intubation

This system of grading is based on actual direct laryngoscopic views

Grade 1-complete glottis visibleGrade 2- visualize only the posterior portion of laryngeal apertureGrade 3- visualize only the epiglottisGrade 4- visualize only the soft palate

CORMACK AND LEHANE CLASSIFICATION

ANTICIPATED DIFFICULT AIRWAY-Discuss with senior colleagues in advance-Test equipment before procedure-Senior help backup-Plan A for ventilation and intubation-Definite Plan B and option of awake

intubation-Ideally, surgery team standby

MANAGEMENT

INTUBATION TROLLEY

Positioning the patient- combines cervical flexion and AO extension(sniffing position)

Opening the patients mouth –scissors maneuver

Technique of tracheal intubation

- Adv tip to base of the tongue by rotating tip around tongue(shd follow natural curve of oropharynx and tongue

-Insert blade to the rt of the tongue’s midline, moving tongue to the lt

-Once the tip of the blade lies at the base of the tongue(just above the epiglottis), apply firm, steady upward and forward traction to the laryngoscoe(45o from the horizontal)

Avoid rotating the laryngoscope, once it is at the base of the tongue to avoid damage to the maxillary teeth

**Stooping limits power in the arms, making it more technically difficult

Performing laryngoscopy

In grade 3 or 4 larynx, epiglottis can be used as landmark for guiding ETT through the hidden vocal cords

Pass tip of ETT underneath epiglottis and anterior to esophagus whiles an assistant applies cricoid pressure(moves larynx posteriorly and helps bring vocal cords into view)

A malleable stylet(has a distal anterior J curve) helps in guiding ETT through the vocal cords

Insertion of the ETT through the vocal cords and removal of the laryngoscope

Ford’s maneuver- Downwards pressure on ETT prior to withdrawing of laryngoscope displaces glottis posteriorly

Note length of ETT at the lips; usually 21-24cm for adult males and 18-22 in adult females(compare with 25cm in nasally intubated cases)

Inflate ETT cuff with enough air to create a seal around ETT during positive pressure ventilation

Absolute confirmation is by observing capnographObserve chest rise and fall with IPPV Listen to apex of each lung field for breath sounds

Confirmation of correct placement and securing the ETT tube

Special trolley with range of euipment such as gum elastic bougie, variety of laryngoscopes and tracheal tubes and cricothyrotomy needles

“ Difficult intubation trolley”

Lighted stylette

bougie guided intubation

Nasopharyngeal airway

LMAGum elastic

bougiesLaryngoscopesMagill’s forcepsFiberoptic scopesLightwands, etc

Airway adjuncts

Manipulation of patient’s airwayUse different blades of laryngoscopeUse of LMA or combitubeCricothyrotomy/Tracheostomy

Options

ASA ALGORITHM

ASA ALGORITHM

Indicated when intubation is deemed not possible or all the above options are unsuitable

Done under local anaesthesia ± iv sedation before induction

Give oxygen and monitor patient closely during procedure

TRACHEOSTOMY

Ensure that the patient is fully conscious prior to extubation. Safer to leave the endotracheal tube in situ if there is any doubt about airway patency post- extubation

Closely observe in the recovery ward for signs of respiratory distress and intervene

Document clearly in the patients case history and anaesthetic record stating the reasons for the difficult intubation and methods used to overcome the problem

Visit the patient post- op and explain about the difficulty in intubation and instruct the patient to inform the next anaesthetist if further anaesthesia is required

POST-OP

Anaesthesia for Medical Students; Pat Sullivan M.D. 1999 Edition; Chapter 6

Difficult Airway Society guidelines for management of the unanticipated difficult intubation; J. J. Henderson,1 M. T. Popat,2 I. P. Latto3 and A. C. Pearce4

Mallampati SR, Gatt SP, Gugino LD, et al: A clinical sign to pre- dictdifficulttrachealintubation: A prospective study. Can J Anaesth 32:429,1985.

Medscape

Practice Guidelines for Management of the Difficult Airway; 2003 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc; Anesthesiology 2003; 98:1269 –77

Samsoon GLT, Young JRB: Diffi- cult tracheal intubation: A retro- spective study. Anaesthesia 42:487,1987.

http://www.airwaycam.com

References

QUESTIONS?????