Introduction to Clinical Airway Management

D. John Doyle MD PhD Professor of Anesthesia

Cleveland Clinic

Clinical Airway Management Series

• Part 1 Introduction to Clinical Airway Management

• Part 2 Airway Gadgets / Fiberoptic Intubation

• Part 3 Lessons from the School of Hard Knocks

• Part 4 Some Interesting Airway Cases

Download this four-part talk series at

http://doyleairwaytalks.homestead.com

OUTLINE

• Goals of Clinical Airway Management• The Past• Preoperative Evaluation of the Airway• Airway Management Options• ETT Placement Confirmation• Supraglottic Airway Devices• Awake Intubation• Transtracheal Jet Ventilation• Video Laryngoscopy• Airway Algorithms

Objectives

At the end of this presentation learners should be familiar with the following:

• Key management decisions to make in difficult airway cases

• Three airway situations you must always have a plan for• The notion of an airway management algorithm• Recognizing situations where intubation will be very difficult • The art and science of awake intubation• Routine and specialized equipment for laryngoscopy /

intubation

Airway Facts1.More than 85% of all respiratory-related

malpractice claims in the US involve a brain-damaged or dead patient (Caplan et al 1990).

2.Poor management of the difficult airway accounts for as many as 30% of deaths due to anesthesia (Benumof and Scheller 1989).

References1. Caplan RA, Posner KL, Ward RJ et al. Adverse respiratory events in anesthesia: a

closed claims analysis. Anesthesiology 72: 828-833 (1990).

2. Benumof JL, Scheller MS. The importance of transtracheal jet ventilation in the management of the difficult airway. Anesthesiology 71: 769-778 (1989).

Three Basic Management Choices...to be made for each airway situation

1. Nonsurgical vs surgical airway for the initial approach to intubation

2. Maintenance of spontaneous breathing vs breathing for the patient

3. Awake intubation vs intubation after induction of general anesthesia

Major Techniques of Airway Management

• Bag mask ventilation

• Endotracheal intubation

• Supraglottic airway devices

• Surgical airway management

Goals of Clinical Airway Management

Choice of technique will depend on management goals …

Clinical Airway Management Has Three Goals:

• Maintenance of adequate oxygenation (as measured by PaO2 or SaO2)

• Maintenance of adequate ventilation (as measured by ETCO2 or PaCO2)

• Protection of the airway from injury (avoiding aspiration, barotrauma, infection etc.)

Oxygenation

Oxygenation is controlled principally by adjusting the fraction of inspired oxygen (FI02 ) setting on the ventilator, although PEEP adjustment is equally important to improve oxygenation in patients with acute lung injury

Oxygenation: PEEP• PEEP or positive end expiratory pressure,

is the minimum lung distending pressure over expiration (see parameter 1 in figure)

• It is usually set between 2 and 5 cm H2O in patients with normal lungs

Oxygenation: PEEP

http://www.aic.cuhk.edu.hk/web8/Hi%20res/Self%20inflating%20resuscitator%20PEEP%20valve.jpg

Controlling Ventilation

• Ventilation is determined by adjusting two things on the ventilator:

tidal volume (TV)

and

respiratory rate (RR) • TV typically 10 ml / kg (unless permissive hypercapnea desired)

• RR typically 10 / min

Protection of the Airway From Soiling and Injury

Protection of the airway from soiling due to aspiration of gastric contents is achieved in unconscious patients (due to general anaesthesia or head injury) by using a cuffed endotracheal tube.

Aspiration Pneumonitis

Unintubated patients may develop deadly aspiration pneumonitis if stomach contents spill into the lungs (especially if the pH is < 2.5 or aspirated volume > 25 ml).

http://www.agai.at/eng/museum/default.htm

McCardie (1865 to 1939) mask for application of open-drop inhalational anesthesia.

THE PAST

Zang mouth gag with the end of the arms protected by rubber from the Collection of Anesthesia and Intensive Care Medicine at the Institute for the History of Medicine in Vienna (Austria) [catalog number 3.47].

http://www.adair.at/eng/museum/equip/mouthgag/zang1.htm

THE PAST

Kuhn tracheal intubation set from the Collection of the Instrument Maker Carl Reiner (Vienna, Austria). The manufacturer is unknown.

http://www.adair.at/eng/museum/equip/tracheal/kuhnintubationsetobject01.htm

About 1900, Franz Kuhn (1866 to 1929, German surgeon) developed a tracheal intubation set. Unfortunately, most of his surgical colleagues did not recognize the importance of tracheal intubation since they were influenced by the surgeon Ferdinand Sauerbruch (1875 to 1951) who refused to use this technique.

THE PAST

http://www.adair.at/eng/museum/equip/tracheal/kuhnintubationsetobject01.htm

THE PAST

Major Techniques of Airway Management

• Bag mask ventilation

• Endotracheal intubation

• Supraglottic airway devices

• Surgical airway management

Key Questions

Is a supraglottic airway appropriate?

Is there a significant aspiration risk?

Will the patient tolerate an apneic period?

Current Airway Management

Options

Option 1 Avoid GA

Avoid general anaesthesia - do case under local or regional anesthesia with patient breathing spontaneously.

Option 2 GA with SV

General anesthesia (e.g. propofol infusion) with patient breathing spontaneously with an unprotected airway and only an oxygen mask.

Option 3 GA with SV General anesthesia with patient

breathing spontaneously with an unprotected airway using a nasopharyngeal airway.

Option 4 SGA with SV

Laryngeal mask airway or other SGA with patient breathing spontaneously (airway still unprotected against aspiration.)

Option 5 SGA with PPV

Positive pressure ventilation (PPV) using the laryngeal mask airway (LMA) or other SGA.

Option 6 ETT with SV Spontaneous breathing with an

airway protected using an endotracheal tube (ETT). An uncuffed ETT was once popular with children, but provides less complete protection against aspiration.

Option 7 ETT with PPV

Positive pressure ventilation (PPV) with an endotracheal tube (ETT). This is the most common option, at least for big cases

Option 8 Surgical Airway

A surgical airway (e.g. tracheostomy under local anesthesia, emergency cricothyroidotomy) may be required in exceptional circumstances.

Transtracheal Jet Ventilation

Preoperative Airway Evaluation

The Difficult Airway is something you anticipate,

The Failed Airway is something you experience.

(Walls, 2002)

Airway Evaluation

• History – interview / records

• Physical exam

• Imaging

Some Clinical Tests

Presence of facial dysmorphic features Atlanto-occipital mobility Mouth opening Visibility of oropharyngeal structures Thyromental distance Sternomental distance Dentition TMJ mobility

Table 1. Components of the Preoperative Airway Physical Examination. This table displays some findings of the airway physical examination that may suggest the presence of a difficult intubation.

Mallampati scoring system - 1983

• MP class I – uvula, soft palate, faucial pillars are noted

• MP class II – part of the uvula, soft palate, faucial pillars are noted

• MP class III – only soft palate and the base of the uvula are visualized

• MP class IV – soft palate is not visualized

Mallampati / Samsoon–Young classification of the oropharyngeal view.

Class I: uvula, faucial pillars, soft palate visible;

Class II: faucial pillars, soft palate visible;

Class III: soft and hard palate visible;

Class IV: hard palate visible only (added by Samsoon and Young).

From

Paul G. Barash, Bruce F. Cullen, Robert K. StoeltingClinical Anesthesia 2001

Mallampati Score Significance

• Poor sensitivity, specificity, PPV (positive predictive value)

• Interobserver variability • Phonation improves specificity, but increases

the false negative results• Poor correlation with difficult bag mask

ventilation• Improved PPV when combined with other clinical

tests

Table 1. Components of the Preoperative Airway Physical Examination. This table displays some findings of the airway physical examination that may suggest the presence of a difficult intubation.

Probability of experiencing a difficult intubation for the combination of risk factors: Mallampati class I, II, III, or IV, short neck (SN), protruding maxillary incisors (PI), or receding mandible (RM). Data were obtained from 1500 patients undergoing cesarean delivery with general anesthesia. Rocke et al.

DL prediction is not VL prediction

Tremblay et al. recorded demographic and morphometric factors for 400 patients undergoing tracheal intubation (TI).

After induction, TI using the GS was performed after the recording of CL grade at DL.

They found a high CL grades at DL, a high upper lip bite test score, and a short sterno-thyroid distance as predictors of difficult GS TI.

Obviously only the last two factors can be assessed at the bedside.

Tremblay MH, Williams S, Robitaille A, Drolet P. Poor visualization during direct laryngoscopy and high upper lip bite test score are predictors of difficult intubation with the GlideScope videolaryngoscope. Anesth Analg. 2008 May;106(5):1495-500

VL DI prediction

Airway Management in the Field

CPR Masks

Laerdal Pocket Mask

Miniature CPR Barrier Masks

The Ambu Res-Cue Key is an inexpensive barrier with a one-way valve that prevents direct mouth-to-mouth contact

The MDI CPR Microkey

OXYLATOR® FR-300

The OXYLATOR® FR-300 limits the maximum airway pressure to 20 cm H2O and maintains a low constant flow rate of 30 liters per minute.

Emergency Suction

Laerdal V-Vac Suction Unit

replacement cartridge

Airway Obstruction

Complete Airway Obstruction

Complete airway obstruction is usually managed by prompt intubation, but surgical airways are sometimes needed as a last resort when neither intubation nor ventilation is possible.

http://images.webmd.com/static54/images/hwstd/medical/pulmonol/n5551303.jpg

Posterior Displacement of Tongue and Soft Palate

Commonly, obstruction occurs, at least in part, when the tongue base falls back posteriorly to obstruct the oropharynx.

Movement of the soft palate may also contribute to airway obstruction.

http://images.webmd.com/static54/images/hwstd/medical/pulmonol/n1573.jpg

Head Tilt

http://www.brooksidepress.org/Products/OperationalMedicine/DATA/operationalmed/Manuals/HM32/Chapter04/fig04-03.gif

Jaw Thrust / Chin Lift

http://www.brooksidepress.org/Products/OperationalMedicine/DATA/operationalmed/Manuals/HM32/Chapter04/fig04-04.gif

Things that Make Mask Ventilation More Difficult

• facial obesity• big, thick beard• large jaw• no teeth• massive facial dressings• recent nasal surgery• delicate skin

(burns, skin grafts, epidermolysis bullosa)

Langeron O, Masso E, Huraux C, Guggiari M, Bianchi A, Coriat P, Riou B: Prediction of difficult mask ventilation. Anesthesiology 2000; 92:1229–36

Airway Adjuncts

Airway adjuncts are often helpful in reducing airway obstruction in spontaneously breathing patients. These include oropharyngeal airways (usually adult sizes 8, 9, 10), nasopharyngeal airways (“nasal trumpets” inserted into one or both nostrils) or a supraglottic airway such as the laryngeal mask airway (LMA).

Oropharyngeal Airway

Nasopharyngeal Airway

Supraglottic Airway Devices

Laryngeal Mask Airway

Laryngeal Mask Airway

Flexible Laryngeal Mask

Proseal Laryngeal Mask

Intubating Laryngeal Mask

http://spaceline.usuhs.mil/current2005/11-04/parabolic_intubation.jpg

Why Intubate?• As part of general anesthesia• Protect airway against aspiration• Allow positive pressure ventilation (PPV)• Allow airway suctioning (toilet)

• Allow drugs to be given in a “code blue” where

IV access is not yet available *–epinephrine– lidocaine–atropine

Methods of Tracheal Intubation

• Blind methods (including digital)

• Use of a laryngoscope

– Macintosh (curved blade)

– Miller (straight blade)

– Videolaryngoscopes

• Trachlight™ and similar methods

• Fiberoptic Intubation

From

Paul G. Barash, Bruce F. Cullen, Robert K. StoeltingClinical Anesthesia 2001

(A) With the patient supine and no head support, the oral, pharyngeal, and tracheal axes do not overlap.

(B) The “sniff” position maximally overlaps the three axes.

Intubation of obese patients can be greatly facilitated by stacking blankets so as to achieve the "head-elevated laryngoscopy position” (HELP)

Troop Elevation Pillow         Patent # US 6,751,818 B1(Mercury Medical)

An Aid To Airway Management For Obese Patients

Normal Glottis

Photo Credit: Dr John Sherry II

Cherry Red Epiglottis (Epiglottitis)

Photo Credit: Dr John Sherry II

Cormack-Lehane Grading System

Grade I: most of glottis is seen Grade II: only posterior portion of glottis can be seen (May not be ASA Task Force "difficult" if some part of the vocal cords are seen.) Grade III: only epiglottis may be seen (none of glottis seen)(ASA Task Force "difficult.") Grade IV: neither epiglottis nor glottis can be seen (ASA Task Force "difficult.")

Endotracheal tube placed fiberoptically through the right orbit, which communicates with the larynx. Sander M. Lehmann C. Djamchidi C. Haake K. Spies CD. Kox M D WJ. Fiberoptic transorbital intubation: alternative for tracheotomy in patients after exenteration of the orbit. Anesthesiology. 97:1647, 2002

http://www.nets.org.au/main/Intub1.jpg

http://www-personal.umich.edu/~bwudcock/Guatemala/Intubation.jpg

Laryngoscopes

Articulating Blade Laryngoscopes

McCoy LaryngoscopeFlexiblade by Arco Medic Ltd.

Macintosh Lighted Stylet

In 1957, Sir Robert Reynolds Macintosh and Harry Richards (Oxford, England, UK) reported on a malleable introducer for tracheal tubes which had an illuminated tip. The proximal end was connected to a pocket battery (Anaesthesia 12:223-225, 1957).

Berman Lighted Stylet

In 1959, Robert A Berman (Far Rockaway, New York, USA) described a malleable introducer for tracheal tubes with an illuminated tip (Anesthesiology 20:382-383, 1959).

http://www.adair.at/eng/museum/equip/stylets/default.htm

Lighted Stylets

Trachlight

Special ETTs

EMT (Emergency Medicine Tube) Endotracheal Tubes

The EMT tracheal tube allows one to administer medications into the patient's lungs without interrupting CPR or disconnecting the tube.

Endotrol® (Trigger Tube)The Endotrol® tracheal tube is designed to facilitate intubation of patients where aid is needed in controlling the direction of the tip of the tube. The operator controls the direction of the tip via a ring loop located near the external connector.

Beck Airway-Airflow Monitor

Magnifies airway-airflow sounds

Activated by patient's respiration

No moving parts

Simple to use

Disposable

The Parker Flex-TipTM tubes are available in sizes 6.5, 7.0, 7.5, and 8.0mm ID.

The tapered, centered, flexible tip of the Parker Flex-TipTM Endotracheal Tube is designed for:

•Better tip visibility

•Gentle sliding off of delicate anatomical structures in the airway

•Easier insertion through narrow glottic openings

•Snag-free "railroading" along fiberoptic scopes

•Gentle "skiing" down tracheal walls

Intubation Bougies

The Eschmann Bougie is a yellow colored, 60 cm, 15 French, stiff stylet marketed by Portex as Catalog Number 103014 and manufactured in England by Eschmann Health Care. It is fabricated from a braided polyester base with a resin coating. It costs around $75 each and can be reused.

Eschmann Bougie

I have found this stylet to be invaluable when faced with a difficult intubation. The technique is simple. If the tip of the epiglottis is visible, slide the upward angled end of the bougie along the bottom of the epiglottis, feeling gently for the unseen glottic opening. It is unlikely that the bougie will be directed into the more posterior esophagus if care is taken to maintain contact with the bottom of the epiglottis. Once the tip is thought to be through the cords, continue to push it into the trachea. With experience, a positive confirmation of tracheal placement can be made by feeling the "clicks" as the angled tip of the bougie passes over the tracheal rings. A 6 or 7 mm endotracheal tube is then passed over the stylet (the modified Seldinger technique for intubation). If the tube hangs up at the cords, simple twisting of the tube will usually allow it to pass.

http://www.calsocanes.com/Bulletins/vol%2047-4/tips984.pdf

If you can’t ventilate or intubate, call for help and open the neck!

Spontaneous breathing is generally safer than paralysis with positive pressure ventilation by mask, especially in cases of airway obstruction

The “awake” airway is the safest airway to manage

Have a low threshold for waking up the elective patient you are having trouble intubating

Fiberoptic intubation is usually ill-advised in dire emergency cases, even with experience. This is especially true with an edematous, bloody airway.

If your first intubation attempt fails ---think about what to do differently for attempt number two.

If you can’t intubate, ventilate! If you cannot intubate in two or three tries, go back to the bag-mask-valve system and contemplate your backup plan

If you can’t ventilate, intubate!

Patients die from failure to oxygenate not from failure to intubate.

If you never use special airway devices in elective cases, you'll definitely not be elegant and slick when you try to use it in an emergency.