AIRWAY MANAGEMENT

Ph ton Thesis

All Rights Reserved with Photon. UBN: 015A94510112004

August, 2014

AIRWAY

MANAGEMENT

Dr. Vijay Kumar, India

MAHATMA JYOTIBA PHULE ROHILKHAND UNIVERSITY,

BAREILLY

“AIRWAY MANAGEMENT”

By

Dr. VIJAY KUMAR

Library Dissertation Submitted To Mahatma Jyotiba Phule Rohilkhand

University, Bareilly

In Partial Fulfillment Of The Requirements For The Degree Of

Master of Dental Surgery

In The Subject Of

ORAL AND MAXILLOFACIAL SURGERY

Year - 2011

KOTHIWAL DENTAL COLLEGE AND RESEARCH CENTRE

i

“AIRWAY MANAGEMENT”

By

Dr. VIJAY KUMAR

Library Dissertation Submitted to Mahatma Jyotiba Phule Rohilkhand

University, Bareilly

In partial fulfillment of the requirements for the degree of

Master of Dental Surgery

In The Subject Of

Oral and Maxillofacial Surgery

Under the guidance of:

DR. MANOJ CHAUDHARY

(Professor / HOD)

Department of Oral and Maxillofacial Surgery

Kothiwal Dental College And Research Centre, Moradabad, U.P. , India

Year - 2011

ii

Dedicated

To

My Parents

And

Brother

iii

DECLARATION BY THE CANDIDATE

I hereby declare that library dissertation entitled

“AIRWAY MANAGEMENT”

MANOJ CHAUDHARY, Professor / HOD., Department Of Oral & Maxillofacial Surgery, Kothiwal Dental College & Research Centre, Moradabad, (U.P).

Date: DR. VIJAY KUMAR

iv

CERTIFICATE BY THE SUPERVISOR

This is to certify that the library dissertation entitled

“AIRWAY

MANAGEMENT”

Oral and Maxillofacial Surgery.

SUPERVISOR

DR MANOJ CHAUDHARY

(Professor / HOD)

CO – SUPERVISORS

DR. SANJAY SINGH DR. S. GOKKULAKRISHNAN (Professor) (Professor)

v

ENDORSEMENT BY THE HOD, PRINCIPAL/HEAD OF THE

INSTITUTION

This is to certify that the library dissertation entitled

“AIRWAY

MANAGEMENT”

Oral and Maxillofacial Surgery, Kothiwal Dental College & Research Centre,

Moradabad, (U.P.)

Seal and Signature of the Seal and Signature of the

(HOD) (Principal)

DR. MANOJ CHAUDHARY DR. SWATANTRA AGARWAL

Date: Date:

vi

ACKNOWLEDGEMENT

It is my great privilege and honor to express the most heartfelt

gratitude and ineptness to

Dr. Manoj Chaudhary

Professor / HOD, Department Of Oral and Maxillofacial Surgery, Kothiwal Dental College & Research Centre Moradabad

Dr. Swatantra Agarwal

Principal

Kothiwal Dental College & Research Centre Moradabad

Dr Sanjay Singh

Professor, Dept of Oral and Maxillofacial Surgery, Kothiwal Dental College & Research Centre Moradabad

Dr. Daya shankara Rao J.K. and Dr. Jinendra Jain

Professor

Dr. S. Gokkulakrishnan

Professor, Department of Oral and Maxillofacial Surgery, Kothiwal Dental College & Research Centre Moradabad

Dr. Harsh Jain M.D.S. Sr. lecturer

Dr. Ashwini N. Shanker, Dr. Manpreet Singh and Dr. Ashish Sharma

Sr. lecturer, Department of Oral and Maxillofacial Surgery, Kothiwal Dental College & Research Centre Moradabad

Mr. Krishan Kant Misra

Director

vii

My senior colleagues, my batch mates Dr. Ashish Kumar Shahi, Dr. Abhishek Singh, and my junior colleagues

viii

TABLE OF CONTENTS

S.No. Particulars Page No.

1. INTRODUCTION 1-2

2. HISTORY OF AIRWAY 3-7 4. ANATOMY AND PHYSIOLOGY OF AIRWAY 8-20 5. OXYGEN DELIVERY SYSTEM 21-25 7. AIRWAY ASSESSMENT 26-32 8. OPENING OF AIRWAYS 33-37 9. ARTIFICIAL AIRWAYS 38-47 10. DEFINITIVE AIRWAYS 48-72 11. AIRWAY MANAGEMENT IN TRAUMA 73-89 12. ADVANCED AIRWAY MANAGEMENT: RSI 90-106 13. BIBLOGRAPHY 107-113

AIRWAY MANAGEMENT Page 1

Airway management is most often needed because of inadequate ventilation, which can result from impaired respiratory effort or airway obstruction. Airway interventions may also be needed to manage the patient with inadequate oxygenation and during cardiopulmonary resuscitation.1, 2, 3

Attaining and maintaining an airway is an essential step in the management of any trauma patients and failure to do so results in drastically increased morbidity and mortality.4 The management of trauma revolves around the ABCDE’s; and are attended in that order.5 During the primary survey, life threatening conditions are identified and reversed quickly. Basically primary survey progresses in a logical manner based on the ABCs: airway maintenance with cervical spine control, breathing and adequate ventilation and circulation with control of haemorrhage. Later D and E have also been added: a brief neurologic examination to establish degree of consciousness and exposure of the patient via complete undressing to avoid any missed undiagnosed injures.6 There are such a vast array of techniques and complicating factors that getting past the first two steps of ‘A’ (airway) and ‘B’ (breathing) can be extremely difficult.4 Thus, being adequately trained and skilled in this area of initial trauma management is essential to not only progress through the ABC’s, but to the patient’s life.4, 5

Since 1993, practice guidelines for airway management have been adopted in the U.S., Canada, France and Italy.7 During the evolution of these guidelines, Airway management in the primary survey may be as simple as positioning of the airway using the chin lift or jaw thrust manoeuvres (used when cervical spine instability is a concern). It may also involve the placement of nasopharyngeal or oral airway devices and the application of supplemental oxygen. In cases of obstruction, foreign bodies may need to be dislodged using basic life support manoeuvres or manually with suctioning and Magill forceps.

INTRODUCTION

AIRWAY MANAGEMENT Page 2

Definitive airway intervention, such as oral endotracheal intubation (with or without rapid sequence technique), nasotracheal intubation or a surgical airway (e.g., cricothyroidotomy) may be required.2

AIRWAY MANAGEMENT Page 3

Art of clinical airway management is as old as medicine itself.8 For instance, there is evidence that the tracheostomy operation was performed on Egyptian tablets dating back to 3,600 BC, while reference to the procedure can be found in ancient Hindu scriptures dating from 2000 BC.9 It is also said that Alexander the Great (356-323 BC) saved a soldier from suffocation by making a tracheal incision using the tip of his dagger.10 Later, in 100 AD, Antyllus described tracheotomy as a horizontal incision between 2 tracheal rings to bypass upper airway obstruction while in 160 AD, the Roman physician Galen wrote, If you take a dead animal and blow air through its larynx (through a reed), you will fill its bronchi and watch its lungs attain the greatest dimension.11

Despite such ancient reports, however, according to Sittig and Pringnitz, before 1,800 only 50 life-saving tracheostomy had been described in the entire medical literature.12 In 1833 Trousseau reported on his experience with 200 diphtheria patients treated with tracheostomy.13 In 1871, Trendelenburg performed a tracheostomy to prevent blood inhalation during upper airway surgery. As experience with the tracheostomy operation grew, consideration to less invasive techniques arose. In 1880, in Scotland, William Macewen described how to relieve airway obstruction by passing an oral tube into the trachea.8 He practiced blind, digital intubation using cadaver models and eventually was able to use this technique clinically.

A few years later, in the USA, Joseph O’Dwyer developed a metal tube system that could be passed blindly to relieve airway obstruction in children suffocating from the pseudo membrane formed with diphtheria infections. Later, George Fell developed an apparatus that could be attached to the O’Dwyer tube system to allow for positive pressure ventilation.14 This combination was used by Fell and others to provide temporary respiratory support in some patients who were apneic from respiratory depressant drugs

HISTORY OF AIRWAY

AIRWAY MANAGEMENT Page 4

such as morphine. The combination was also used to treat patients with pneumothoraces and to allow for thoracic surgical procedures. Across the ocean in Germany, Hans Kuhn modified O’Dwyer’s tube system to create a flexometallic endotracheal tube with matching introducer intended for blind insertion. One important problem with the O’Dwyer intubation system and its variants was that they had to be placed blindly.15 The next important development in clinical airway management was thus the development of direct laryngoscopy, which allowed visualization of the glottic structures. Manual Garcia (1805-1906), in London, England is commonly credited with the discovery of laryngoscopy. In 1855, he described how he could perform autolaryngoscopy through the use of a dental mirror in combination with a second, larger mirror used to direct sunlight into his mouth.16 In this arrangement operator see his larynx and trachea because absent of gag reflex.

Earlier, Benjamin Guy Babington created a glottiscope in 1829.17 Unfortunately, the invention did not have the impact it deserved. A number of years later, towards the end of the 19th century, Kirstein developed an instrument he called an autoscope.18 The idea for this instrument came to Kirstein after he learned how an endoscope intended for esophagoscopy had inadvertently slipped into the trachea. His design was subsequently modified by Jackson by providing distal illumination with a tungsten light bulb and other modifications.

The 1940s saw the development of the Miller and MacIntosh laryngoscopes in common clinical use today. In 1941, Robert Miller described his straight laryngoscope blade,19 while in 1943 Robert MacIntosh described his curved blade.20 At the same time, in Montreal, Canada in 1942, Harold Griffith introduced curare as a muscle relaxant with a

AIRWAY MANAGEMENT Page 5

view to facilitating abdominal surgery and other procedures.21 As a result, tracheal intubation became routine in major surgical procedures.

Although 60 years later variations of the MacIntosh and Miller laryngoscopes are still in common use, because both occasionally fail to provide adequate glottic views, efforts to improve on their designs have continued. The result has been a continuing series of innovations in laryngoscope design, including developments such as fiberoptic bronchoscopes optimized for intubation, the Bullard laryngoscope and its variants, the McCoy articulating laryngoscope, various optical stylettes, and video laryngoscopes such as the GlideScope and the McGrath video laryngoscope.

Finally, any history of airway management would be incomplete without mentioning supraglottic airway devices such as the Laryngeal Mask Airway (LMA). Dr. Archie Brain, the inventor of the LMA, went through a considerable variety of prototype designs before the clinical launch of the LMA in the 1980s. Many people are unaware, however, that other supraglottic airway were in clinical use long before the invention of LMA, although these devices were eventually eclipsed by the popularization of tracheal intubation following the popularization of curare.

HISTORY OF AIRWAY

AIRWAY MANAGEMENT Page 6

Important landmarks in clinical airway management

Biblical Times Death from airway obstruction recognized (trauma, strangulation, leprosy, abscesses)

1700s Metal and leather tubes inserted blindly into the trachea for treatment of drowning.

1842 Crawford Long discovers ether anesthesia.

1854 Garcia, a professor of singing, develops indirect laryngoscopy.

1878 Chloroform administered through tracheal tube (MacEwen).

1885 O’Dwyer popularizes intubation for diphtheria.

1895 Kirstein develops direct laryngoscopy.

1900 Kuhn develops a flexometallic tracheal tube.

World War I Many casualties requiring head and neck surgery adds impetus to widespread use of intubation in military hospitals; Magill introduces tracheal tube with

inflatable cuff.

1920 Chevalier Jackson designs improved laryngoscope.

AIRWAY MANAGEMENT Page 7

1942 Griffiths introduces curare into clinical practice.

1946 Mendelson describes aspiration pneumonitis.

1950s Popularization of the use of tracheal tubes for general anesthesia.

1960s Advent of electronic patient monitoring.

1962 Sellick maneuver and rapid-sequence induction developed.

1940s-1970s Continuing improvements in laryngoscope and tube designs; use of plastic,

1970s Development of implant-tested low-irritation, low-cuff pressure disposable tracheal tubes.

1980s Popularization of fiberoptic intubation. Introduction of pulse oximetry and capnography as non-invasive means of assessing oxygenation and ventilation.

1990s Popularization of laryngeal mask airway, rigid fiberoptic laryngoscopes and ASA Practice Guidelines for Management of the Difficult Airway. Increased

awareness of the special challenges of the (difficult extubation) patient.

ANATOMY AND PHYSIOLOGY OF AIRWAY

AIRWAY MANAGEMENT Page 8

Successful airway management requires an understanding of upper and lower airway structure and function.22

A. UPPER AIRWAY:

Upper airway consists of the structures above the vocal cords

The human airway has two openings: the nose and the mouth. The nose leads to the nasopharynx and the mouth leads to the oropharynx. Separated anteriorly by the palate, these two passages join posteriorly in the pharynx. At the base of the tongue, the epiglottis separates the oropharynx and the laryngopharynx. The larynx then extends to become the trachea lying parallel in front of the oesophagus.

Nasopharynx: The nasopharynx is situated behind the nasal cavity, above the soft palate.

It contains the pharyngeal tonsils in its posterior wall.

Oropharynx: The oropharynx is encompassed by the soft palate above and the epiglottis

below. It contains the palatine tonsils.

Palate: The palate forms the roof of the mouth and the floor of the nasal cavity. The hard

palate forms the anterior four-fifths of the palate and is a bony framework covered with a mucous membrane. The soft palate is a fibromuscular fold that moves posteriorly against the pharyngeal wall to close the nasopharyngeal cavity when swallowing or speaking.

Pharynx: The pharynx is a U-shaped fibromuscular structure located between the oral

and nasal cavities and posterior to the larynx. It is subdivided into the nasopharynx, oropharynx, and laryngopharynx/hypopharynx. It extends from the base of the skull to the inferior border of the cricoid cartilage anteriorly (at the entrance of the oesophagus) and the inferior border of the C6 vertebra posteriorly. The pharynx conducts food to the

AIRWAY MANAGEMENT Page 9 oesophagus and air to the larynx, trachea and lungs. It opens anteriorly into the nasal cavity, mouth and larynx (naso- , oro-, and laryngo- pharynx, respectively) and to the oesophagus inferiorly. The wall of the pharynx is composed of two layers of pharyngeal muscles: the external circular layer consists of constrictors and the internal longitudinal layer consists of muscles that elevate the larynx and pharynx during swallowing and speaking.

Epiglottis: The epiglottis is a spoon shaped plate of elastic cartilage that lies behind the

tongue. It prevents aspiration by covering the glottis – the opening of the larynx - during swallowing.

Laryngopharynx/Hypopharynx: The laryngopharynx/hypopharynx extends from the

upper border of the epiglottis to the lower border of the cricoid cartilage.

Larynx: It is a tubular structure that connects the laryngopharynx with the trachea. They

serve as the organ of phonation and a valve to protect the lower airways from the contents of the alimentary tract. It lies anterior to the 4th, 5th and 6th cervical vertebrae in the adult. It is involved in respiration, phonation, deglutition and effort closure.

Interior of the larynx: The entrance of larynx bounded anterior by the epiglottis and the

median epiglottis ligament. The lateral boundaries are defined by the aryepiglottic folds, which enclose aryepiglottis muscle and the cuneiform and corniculate cartilages. The posterior border is the interaretenoid fold of mucous membrane enclosing transverse arytenoids muscle. The piriform fossae are the depressions between the aryepiglottic folds and the lateral wall of the pharynx. Beyond the inlet of larynx lie the ventricular (false cords) and vocal folds. The vocal folds contain vocal ligaments and vocal process of arytenoids cartilage.

AIRWAY MANAGEMENT

Framework of larynx: It is formed by single thyroid, cricoid and paired arytenoids, corniculate and cuneiform cartilage.

signet ring. It forms two joints (with thyroid and arytenoid cartilage). Involvement of these joints causes hoarseness of voice and

Sensory innervations: The internal branch of superior laryngeal nerve (SLN) branch of

vagus nerve that supplies mucous membrane till vocal folds. After it pierces thyrohyoid membrane, it lies just below the mucosa

laryngeal nerve innervates the mucous membrane below the vocal folds.

Cricoid cartilage Thyroid (laryngeal) cartilage

Hyoepiglottic ligament

ANATOMY AND PHYSIOLOGY OF AIRWAY

It is formed by single thyroid, cricoid and epiglottis cartilages and the paired arytenoids, corniculate and cuneiform cartilage. The cricoid cartilage is shaped like signet ring. It forms two joints (with thyroid and arytenoid cartilage). Involvement of these joints causes hoarseness of voice and occasionally difficulty with intubation.

The internal branch of superior laryngeal nerve (SLN) branch of vagus nerve that supplies mucous membrane till vocal folds. After it pierces thyrohyoid membrane, it lies just below the mucosal surface of the piriform fossa. The recurrent laryngeal nerve innervates the mucous membrane below the vocal folds.

Cricoid cartilage Thyroid (laryngeal) cartilage Hyoepiglottic ligament Hyoid bone

Epiglottis Vallecula

Major nasal airway Inferior turbinate

ANATOMY AND PHYSIOLOGY OF AIRWAY

Page 10 epiglottis cartilages and the The cricoid cartilage is shaped like signet ring. It forms two joints (with thyroid and arytenoid cartilage). Involvement of

occasionally difficulty with intubation.

The internal branch of superior laryngeal nerve (SLN) branch of vagus nerve that supplies mucous membrane till vocal folds. After it pierces thyrohyoid l surface of the piriform fossa. The recurrent laryngeal nerve innervates the mucous membrane below the vocal folds.23, 24

Epiglottis Vallecula

Major nasal airway Inferior turbinate

AIRWAY MANAGEMENT Page 11

Laryngeal Variations in the infant

Head

Infant Adult

Relatively larger Relatively smaller

Tongue Relatively larger Relatively smaller

Epiglottis Long thin, stiff ‘U’ shaped 45 degree to

trachea

Shorter, wider, flat flexible, parallel to

trachea

Laryngeal inlet Level of C3 – C4 Junction

Level of C4 – C5 junction

Cricoid Level of C4 – C5 Junction

Level of C6

ANATOMY AND PHYSIOLOGY OF AIRWAY

AIRWAY MANAGEMENT Page 12

B. LOWER AIRWAY

Lower airway consists of the respiratory structures below the larynx

The Conducting Zone: At the carina, the trachea bifurcates into the right and left main

bronchi. The right and left main bronchi further branch into increasingly smaller bronchi and finally the terminal bronchioles, which are the smallest airways without alveoli. The conducting airways serve to lead inspired air to the gas-exchanging regions downstream. The conducting airways contain NO ALVEOLI and, thus, do not take part in gas exchange. The conducting zone of the airway constitutes the anatomical ‘dead space’ (150ml).

Trachea: The trachea begins at the inferior border of the cricoid cartilage (C6) and continues about 9-15 cm in length until it bifurcates into the right and left main bronchi at the level of the sternal angle (junction of T4 and T5). It is composed of 16-20 incomplete cartilaginous rings that open posteriorly. These incomplete rings prevent the trachea from collapsing and allow for changes in calibre, which can be important in changing airway resistance and in generating a cough.

Carina: The carina is a downward and backward projection of the last tracheal cartilage.

It forms a ridge that separates the opening of the right and left main stem bronchi. It occurs at the sternal angle, the junction of T4 and T5.

Right and Left Main Bronchus: The right and left main bronchi pass inferolaterally

from the bifurcation of the trachea to the lungs. They are supported by cartilaginous rings. The right main bronchus is wider, shorter, and more vertical than the left, and thus is the more common side of aspiration and foreign body obstruction. Both main bronchi

AIRWAY MANAGEMENT Page 13 accompany the pulmonary arteries into the hila of the lungs and branch within the lung to form the bronchial tree.

Bronchopulmonary Segment: The bronchopulmonary segment is the anatomical,

functional, and surgical unit/subdivision of the lung and refers to the portion of the lung supplied by each segmental/tertiary bronchus and segmental/tertiary artery. It consists of the segmental/tertiary bronchus, a segmental branch of the tertiary artery (branch of pulmonary artery), a segment of the lung tissue, and the surrounding connective-tissue septum. The bronchopulmonary segment is important because a surgeon can remove one segment without seriously disrupting surrounding segments.

Diaphragm: The Diaphragm is the most important muscle for inspiration. When the

diaphragm contracts, the abdominal contents are pushed downward, increasing the volume and decreasing the pressure in the thoracic cavity. Remember the pneumonic: C3, C4, C5 keep the diaphragm alive – referring to the level of origin of the phrenic nerves in the cervical spine.

Thoracic Cage: The muscles of the thoracic cage lift the ribs upwards and outwards. The

external intercostals and the accessory muscles are used only during exercise/exertion, not during normal quiet breathing. If they are sucked inwards by forcible inspiration, this often indicates increased work of breathing and impending respiratory failure.

Surfactant: Surfactant is a surface-active lipoprotein complex that formed by type

II alveolar cells. Surfactant contains a hydrophilic region and a hydrophobic region. These two regions play an important role at the time of air-water adsorption. Here hydrophilic head groups face towards the water and hydrophobic tails facing towards the air. The main lipid component of surfactant is Dipalmitoyl phosphatidylcholine (DPPC) and it main function is to reduce surface tension. Role of surfactant during airway

AIRWAY MANAGEMENT maintenance is: to increase

lung) at the end of expiration and to facilitate recru

Compliance: Compliance is the ability of the lung to stretch; its distensibility. It

represents the change in volume that occurs for a given change in pressure.

The Respiratory Zone: The terminal bronchioles divide into respira

have occasional alveoli budding from their walls. These terminate into the alveoli/alveolar sacs. There are over 300 million alveoli in the human lung and each alveolus is covered in an extensive network of capillaries for air/gas exc

respiratory zone makes up most of the lung (2.5

APPLIED ANATOMY OF AIRWAY

In managing the airway,

assist the laryngoscopist in a number of ways. It is important to apply this understanding in overcoming airway obstruction during loss of consciousness, in providing adequate

ANATOMY AND PHYSIOLOGY OF AIRWAY

o increase pulmonary compliance, to prevent atelectasis lung) at the end of expiration and to facilitate recruitment of collapsed airways.

Compliance is the ability of the lung to stretch; its distensibility. It represents the change in volume that occurs for a given change in pressure.

The terminal bronchioles divide into respiratory bronchioles that have occasional alveoli budding from their walls. These terminate into the alveoli/alveolar sacs. There are over 300 million alveoli in the human lung and each alveolus is covered in an extensive network of capillaries for air/gas exc

respiratory zone makes up most of the lung (2.5-3L).

APPLIED ANATOMY OF AIRWAY

In managing the airway, knowledge of anatomic structures and their relationships can assist the laryngoscopist in a number of ways. It is important to apply this understanding in overcoming airway obstruction during loss of consciousness, in providing adequate

ANATOMY AND PHYSIOLOGY OF AIRWAY

Page 14 atelectasis (collapse of the itment of collapsed airways.

Compliance is the ability of the lung to stretch; its distensibility. It represents the change in volume that occurs for a given change in pressure.

tory bronchioles that have occasional alveoli budding from their walls. These terminate into the alveoli/alveolar sacs. There are over 300 million alveoli in the human lung and each alveolus is covered in an extensive network of capillaries for air/gas exchange. The

knowledge of anatomic structures and their relationships can assist the laryngoscopist in a number of ways. It is important to apply this understanding in overcoming airway obstruction during loss of consciousness, in providing adequate

AIRWAY MANAGEMENT Page 15 exposure of the glottis during direct laryngoscopy, and in the application of various tools and adjuncts when direct laryngoscopy proves difficult or impossible.

Externally, important landmarks include the hyoid bone, cephalad to the larynx, and the large, unpaired cartilages of the larynx. These consist of the shield-shaped thyroid cartilage and the signet ring-shaped cricoid cartilage below it. Between these cartilages lies the cricothyroid interval, through which several emergency airway devices can be placed. Below the cricoid cartilage, the tracheal rings are palpable.

During direct laryngoscopy, while viewing the glottis from above, several features are apparent. The vestibular folds, or false cords, lie above the true vocal folds. The vocal folds, or true cords, may or may not be well-visualized when the glottic opening is exposed.

In a sagittal and a coronal cross-section of the larynx, it can be seen that the vocal ligaments traverse the distance between the thyroid cartilage, anteriorly, and the arytenoid cartilages, which are perched atop the cricoid cartilage, posteriorly. The arytenoids serve as a point of origin for several intrinsic laryngeal muscles, which move the true vocal cords to produce phonation. Inferior to the vocal folds is the circumferential ring of the cricoid cartilage. Its inferior aspect marks the proximal tracheal lumen.

In the supine position, during unconsciousness, relaxation of the muscles supporting the airway frequently leads to upper airway obstruction. This occurs primarily at the level of the soft palate and tongue, and can usually be overcome by jaw thrust, chin lift, or insertion of an oropharyngeal or nasopharyngeal airway.25

A number of structures may obstruct the laryngoscopist's view of the laryngeal inlet. A cadaver specimen sectioned in the sagittal plane that makes evident of difficulty. Mouth

ANATOMY AND PHYSIOLOGY OF AIRWAY

AIRWAY MANAGEMENT Page 16

opening at the temporomandibular joint, oral cavity size, dental structures, and tongue size are immediately apparent as obstructions to visualization of the glottis. Furthermore, the angle at which one attempts to bring the airway entrance into view is of importance. In neutral position, the line of sight reaches the posterior pharynx, uvula, and soft palate. With extension, it is possible to view the hypopharynx, the area just cephalad to the glottic opening. When the patient's head is placed in the sniffing position (flexion of the cervical spine and extension of the atlanto-occipital joint), the axes of the airway are better aligned. This has become the standard patient position for optimizing the view of the airway during direct laryngoscopy.

Innervation of the key airway structures:- The internal branch of the superior laryngeal

nerve innervates the laryngeal mucosa above the vocal folds, including that of the laryngeal surface of the epiglottis. Above this level, the glossopharyngeal nerve is responsible for sensation in the posterior tongue, vallecula, and pharynx, while the lingual nerve, a branch of Cranial Nerve VII, supplies sensation to the anterior tongue.

The afferent limb of the gag reflex is primarily served by the glossopharyngeal nerve, and the muscles of the pharynx is innervated by the vagus nerve that also play an important role in gag reflex through efferent limb.

Below the level of the vocal cords, the recurrent laryngeal nerves supply sensation. All of the intrinsic muscles of the larynx are innervated by the recurrent laryngeal nerve, with the exception of the cricothyroid muscles, which are innervated by the external branch of the superior laryngeal nerve. Understanding these innervation patterns is useful when providing topical anesthesia or nerve blocks for awake intubation utilizing a fiberoptic bronchoscope.

AIRWAY MANAGEMENT Page 17 C. AIRWAY PHYSIOLOGY:

Respiration occurs primarily to provide oxygen to cells for aerobic metabolism. Effective oxygenation based on these three mechanisms:

1. Oxygenation at the lungs; 2. Transport of oxygen; and

3. Release of oxygen at the cellular level.

A breakdown of any these tasks can result in hypoxia/ischemia.

Gas exchange occurs primarily at the surface of the alveoli (the respiratory bronchioles also engage in gas exchange but too much lesser extent than the alveoli). Oxygen crosses fairly freely into the blood, providing a partial pressure (Pao2) in the blood of about 80-100 mm Hg. The venous circulation has a Pao2 of about 40 mm Hg.

While most instances of poor oxygenation produce cyanosis, carbon monoxide (CO) poisoning is the exception. Haemoglobin’s affinity for carbon monoxide is about 240 times that of oxygen. Carbon monoxide quickly binds to hemoglobin at the sites usually reserved for oxygen. This causes the hemoglobin to reflect a bright red hue typical of full oxygen saturation. While CO poisoning is indeed responsible for severe oxygen depletion, the patient presents without cyanosis (white skinned people become a cherry red). Treatment includes the provision of high flow oxygen.

Several disease processes can impair gas exchange. This includes airway obstruction, respiratory failure, carbon monoxide poisoning and low oxygen gradient (i.e. high altitude where atmospheric Pao2 is low). For example, emphysema restricts the flow of air into

ANATOMY AND PHYSIOLOGY OF AIRWAY

AIRWAY MANAGEMENT Page 18

and out of the lungs, impairing gas exchange at the alveoli. The pulse oximeter is a simple, non-invasive device used to measure the blood oxygen saturation.

Ventilation and Changing Pressures: Air moves from an area of high pressure to an

area of lower pressure. A lung air pressure that is lower than atmospheric pressure causes air to flow into the lungs. This is accomplished by increasing the volume of the closed thoracic cavity (inspiration). By increasing the lung volume, air pressure within the lung drops.

In a closed system, pressure is inversely related to volume: In other words, in a closed

system pressure decreases when volume increases. Conversely, pressure increases as volume decreases. Therefore, by increasing lung volume, intrapleural (lung) pressure drops below atmospheric pressure and air rushes into the lungs. This negative pressure ventilation - better known as breathing spontaneously - is how we move air into our lungs.

To review, inspiration causes the pleural cavity to increase, intrapleural pressures become negative, and air moves from an area of higher pressure (the atmosphere) to an area of lower pressure (the alveoli). During expiration the intrapleural pressures are increased in relation to atmospheric pressure as the closed thoracic cavity decreases in size. This causes air to flow back out to the atmosphere.

For patients who require assistance breathing, a ventilator or bag valve mask (BVM) delivers air forcefully into the lungs. The air pressure created by the action of these devices is higher than the air pressure in the lungs. This is positive pressure ventilation (PPV) and it has many benefits in cardiovascular emergencies. For example, PPV can help expand collapsed alveoli or cause fluids to be forced out of the lungs and into the blood stream i.e. pulmonary edema.

AIRWAY MANAGEMENT Page 19 Positive pressure ventilation does have its disadvantages. Positive pressure ventilation can rupture the lung causing a tension pneumothorax. Also, positive pressure ventilation can increase the positive end expiratory pressure (PEEP) within the lungs. Additional PEEP increases the pressure on the pulmonary vasculature and reduces the venous return (preload) to the heart. While the reduction of preload may benefit those in left ventricular failure, those who are critically dependent on preload (i.e. acute right ventricular infarction or low cardiac output states) may deteriorate with high PEEP.

D. LUNG VOLUMES AND CAPACITIES:

Remember: Capacities are always the summation of volumes.

Tidal Volume (VT): The volume of gas moved into or out of the lung in a single normal

inspiration or expiration

Inspiratory Reserve Volume (IRV): Maximum volume that can be inspired over the

inspiration of a tidal volume/normal breath. Used during exercise/exertion.

Expiratory Reserve Volume (ERV): Maximal volume that can be expired after the

expiration of a tidal volume/normal breath.

Residual Volume (RV): Volume that remains in the lungs after a maximal expiration.

Cannot be measured by spirometry.

Inspiratory Capacity (IC): Volume of maximal inspiration: IRV + VT

Functional Residual Capacity (FRC): Volume of gas remaining in lung after normal

expiration, cannot be measured by spirometry because it includes residual volume: ERV + RV

ANATOMY AND PHYSIOLOGY OF AIRWAY

AIRWAY MANAGEMENT Page 20

Vital Capacity (VC): Volume of maximal inspiration and expiration: IRV + VT + ERV

= IC + ERV

Total Lung Capacity (TLC): The volume of the lung after maximal inspiration. The

sum of all four lung volumes cannot be measured by spirometry because it includes residual volume: IRV+ VT + ERV + RV = IC + FRC

Dead Space: Volume of the respiratory apparatus that does not participate in gas

exchange, approximately 300 ml in normal lungs.

Anatomic Dead Space: Volume of the conducting airways, approximately

150 ml

Physiologic Dead Space: The volume of the lung that does not participate

in gas exchange. In normal lungs, is equal to the anatomic dead space (150 ml). May be greater in lung disease.

AIRWAY MANAGEMENT Page 21 There are three types of oxygen delivery system:

(A)Low flow devices (B)High flow devices

(C)Fraction of inspired oxygen - FiO2

(A) LOW FLOW DEVICES: It delivers oxygen at rates less than inspiratory flow rate,

so room air is also breathed in. The inspired oxygen delivery is variable (FiO2 = Fraction of inspired oxygen). Low flow devices deliver less than 30litres/minute.

(a) Nasal cannula (b) Simple face masks (c) Non rebreathing mask (d) Tusks

(a) Nasal cannula: They are Lightweight and generally comfortable for patient while

eating or drinking. Indicated in case of COPD and proven CO2 retention. Its appropriate flow rate is < 5L/min for adults and very low flows in children. Flow rate is >4L/min cause painful drying of the nasal mucosa. If flow rates are 1-2L/min then FiO2 lies in between 24-28% while flow rate is 2-4L/min then FiO2 is 28-34%.22,26

OXYGEN DELIVERY SYSTEM

AIRWAY MANAGEMENT Page 22

(b) Simple face masks: It increases oxygen reservoir but may be uncomfortable,

claustrophobic, and hot on face along with drying irritation to eyes and airway. Fit as tightly as possible for appropriate functioning. Multiple holes present on either side of simple face mask that causes entrain room air and release exhaled gases while taping holes will not increase concentration of oxygen delivered but addition of ‘tusks’ or a reservoir bag will increase oxygen levels.

If flow rates are 5-6L/min then it provides 40% FiO2 and 7-8L/min then FiO2 is 60% but use of more than 10L/min does not increase FiO2. More than 5L/min flow rates is used to prevent accumulation of exhaled gases.

(c) Non-rebreathing mask: It provides highest oxygen concentration that is about 80%

oxygen at flow rates of 10-15L/min. Patient breathes from mask and one way valve opens to allow breath to come from reservoir bag so no room air is taken. The mask fitting and breathing pattern affect the amount of gas delivered and the amount of room air entrained. Ensure the reservoir bag remains at least a quarter filled at all times. It is commonly used in critically ill patients.26

AIRWAY MANAGEMENT Page 23 (d) Tusks: It is a poor man’s version of rebreathing system. It differs from

Non-rebreathing mask in tusk wide bore tubing added to holes on mask that acts as reservoir. (B) HIGH FLOW DEVICES: It Deliver fixed flow rates that meet inspiratory requirements by entraining room air to deliver fixed concentrations of oxygen.

(a) Venturi mask (b) Aqua paks

High flow devices are fixed performance masks and deliver 30 – 40 L/min of gas with fixed oxygen concentration. That achieved by dilution of oxygen by air through venturi valve. Concentration of oxygen fixed depending on valve used irrespective of oxygen flow. Later on heat and humidity may be added to improve patient comfort.

(a).Venturi mask: It is similar to simple face mask but has jet adaptor with graduated

FiO2 measurement and corresponding flow rates. If requirement of oxygen is more than 40% venturi mask may not have enough total flow to meet high inspiratory demands because here oxygen flows through restricted orifice (smaller the orifice the greater the

OXYGEN DELIVERY SYSTEM

AIRWAY MANAGEMENT Page 24

pressure drops). It provides more accurate prediction of FiO2 and indicated in cases of COPD and accurately control inspired oxygen level is required.22,26

(b).Aqua Paks: It was a FiO2 regulator and uses along with venturi system. It required additional humidification to system that prevents airway drying mobilises secretions and warms air.

Venturi mask

AIRWAY MANAGEMENT Page 25 (C) FRACTION OF INSPIRED OXYGEN - FiO2: FiO2 mainly depends upon three factors like patient ventilation, mask seal and peak inspiratory flow rate.

Oxygen flow rate L/min Approximate FiO2

Room air 21%

4L/min 35%

6L/min 50%

8L/min 55%

10L/min 60%

12L/min 65%

AIRWAY ASSESSMENT

AIRWAY MANAGEMENT Page 26

Careful assessment of the airway is an essential component of every preoperative visit. Difficulty in airway management is the single most important cause of anaesthesia-related morbidity and mortality. It has been estimated that as many as 30% of deaths totally attributable to anaesthesia are associated with inadequate airway management.

The site and nature of the proposed surgery, the type of anaesthetic selected and patient factors will determine a plan for airway management by the anaesthetist. It may be obvious that a patient's airway will be difficult (e.g. masses, abscesses, anatomical abnormalities, etc.), but most catastrophes happen when unexpected difficulty occurs. Assessment of the airway involves taking a history, examination, and the use of a few simple bedside tests.

History: Ask about previous anaesthetics and scrutinize previous anaesthetic records.

Check for previous airway problems. If the patient was intubated there should be a comment about the best view obtained of the glottis as graded by Cormack and Lehane. Record previous airway or intubation problems and rule out is the underlying problem still present? Is there a history of dental damage or severe sore throat with previous anaesthetics?

Ascertain whether the patient has had previous head and neck surgery, radiotherapy to the head and neck, or has medical conditions that may predispose to difficult tracheal intubation-diabetes mellitus, acromegaly, rheumatoid arthritis, cervical arthropathy, morbid obesity, or obstructive sleep apnoea. Patients with Down's syndrome or degenerative cervical spine disease are at increased risk of atlantoaxial instability. An occasional patient may have written notification of previous airway problems.

AIRWAY MANAGEMENT Page 27

Physical examination: In assessing patient 4 areas should be evaluated properly for signs

that may suggest difficulty.

a. Limited volume or displacement of tongue during laryngoscopy. a) Short muscular neck with full set of teeth

b) Receding mandible with obtuse mandibular angle.

c) Long narrow mouth (usually associated with high arched palate)

d) Thyroid cartilage to mental distance of less than 6 cm (3 finger’s breadth). b. Limitation to inserting laryngoscope or obtaining straight line of sight to the

glottis.

a) Maxillary prognathism

b) Large breasts/extreme truncal obesity

c) Increased distance from mandibular alveolar ridge to lower mental boarder requiring wide mouth opening.

c. Limitation of mouth opening: a) Arthritis of bone b) Trismus

c) < 4 cm (2 finger breadth) between incisors on mouth opening. d. Limitation of mobility of cervical spine.

AIRWAY ASSESSMENT

AIRWAY MANAGEMENT Page 28

b) Lack of ability to flex or extend head atlanto occipital joint. c) Symptoms cervical nerve encroachment on head extension.

d) Reduction of distance between the occipital bone and spinous process of C1 on lateral neck X-ray.

Clinical tests:

These are used in an attempt to predict difficult laryngoscopy (i.e. Cormack and Lehane grades 3 and 4), which occurs in approximately 1–2% of the surgical population. Ideally, these tests should have a high specificity (the ability to correctly identify normal patients as normal) and a high sensitivity (to detect true difficult intubations).

No single test can be used to predict difficult laryngoscopy with certainty. Combining two or more tests improves the positive predictive value (the percentage of difficult laryngoscopies correctly predicted as difficult) and increases the specificity, but decreases the sensitivity.

Prediction of difficult laryngoscopy is imprecise. The tests described have high specificities (that is they are good at predicting when laryngoscopy will be easy). Since the same factors are involved in easy laryngoscopy and successful airway maintenance with a mask (extension at the craniocervical junction and mandibular protrusion), predicting easy laryngoscopy is also a prediction of successful control of the airway changes associated with induction of anaesthesia.

If several of the tests are positive the clinician should have a high index of suspicion that direct laryngoscopy will be difficult and consider securing the airway before inducing anaesthesia.

AIRWAY MANAGEMENT

Cormack and Lehane classification:

Cormack and Lehane classification of glottic visualization

Grade I: Most of the glottis is seen

Grade 2: Only posterior portion of glottis can be seen

Grade 3: Only epiglottis seen (none of glottis seen)

Grade 4: Neither epiglottis nor glottis can be seen

Interincisor gap:

Ask the patient to open their mouth as wide as possible.

Less than two finger breadths (3 cm) distance between the incisor teeth is associated with difficulty in conventional laryngoscopy.

An interincisor gap of less than 3 cm reduced the prevalence of easy intubation from 95% to 62% in one large series.

Protrusion of the mandible:

Ask the patient to protrude their mandible. Look at the position of the lower teeth in relation to the upper teeth. Classes B and C are associated with difficult laryngoscopy:

mack and Lehane classification:

Cormack and Lehane classification of glottic visualization

Most of the glottis is seen

Only posterior portion of glottis can be seen Only epiglottis seen (none of glottis seen)

piglottis nor glottis can be seen

Ask the patient to open their mouth as wide as possible.

Less than two finger breadths (3 cm) distance between the incisor teeth is associated with difficulty in conventional laryngoscopy.

interincisor gap of less than 3 cm reduced the prevalence of easy intubation from 95% to 62% in one large series.

Protrusion of the mandible:

Ask the patient to protrude their mandible. Look at the position of the lower teeth in . Classes B and C are associated with difficult laryngoscopy:

Page 29

Cormack and Lehane classification of glottic visualization

Less than two finger breadths (3 cm) distance between the incisor teeth is

interincisor gap of less than 3 cm reduced the prevalence of easy intubation

Ask the patient to protrude their mandible. Look at the position of the lower teeth in . Classes B and C are associated with difficult laryngoscopy:

AIRWAY MANAGEMENT

Class A: the lower incisors can be protruded anterior to the upper incisors. Class B: the lower incisors can be brought ‘edge to edge’ with the upper incisors. Class C: the lower incisors cannot

Mallampati test (Samsoon and Young modification)

Mallampati test (with Samsoon and Young's modification):

Sit in front of the patient who should be sitting up with their head in the neutral position. Ask the patient to open th

phonating.27 Note which of the following structures are visible:

Class 1: Faucial pillars (palatoglossal and palatopharyngeal folds), soft palate, and uvula visible.

Class 2: Faucial pillars and soft p Class 3: only soft palate visible. Class 4: soft palate not visible.

NOTE: Class 3 and 4 views are associated with difficulty. When used in isolation the Mallampati test correctly identifies about 50% of

AIRWAY ASSESSMENT

Class A: the lower incisors can be protruded anterior to the upper incisors. Class B: the lower incisors can be brought ‘edge to edge’ with the upper incisors. Class C: the lower incisors cannot be brought ‘edge to edge’.

Mallampati test (Samsoon and Young modification)

Mallampati test (with Samsoon and Young's modification):

Sit in front of the patient who should be sitting up with their head in the neutral position. Ask the patient to open their mouth maximally and protrude their tongue without

Note which of the following structures are visible:

Class 1: Faucial pillars (palatoglossal and palatopharyngeal folds), soft palate,

Class 2: Faucial pillars and soft palate visible. Uvula masked by base of tongue. Class 3: only soft palate visible.

Class 4: soft palate not visible.

NOTE: Class 3 and 4 views are associated with difficulty. When used in isolation the Mallampati test correctly identifies about 50% of difficult intubations.

AIRWAY ASSESSMENT

Page 30

Class A: the lower incisors can be protruded anterior to the upper incisors. Class B: the lower incisors can be brought ‘edge to edge’ with the upper incisors.

Mallampati test (Samsoon and Young modification)

Sit in front of the patient who should be sitting up with their head in the neutral position. eir mouth maximally and protrude their tongue without

Class 1: Faucial pillars (palatoglossal and palatopharyngeal folds), soft palate,

alate visible. Uvula masked by base of tongue.

AIRWAY MANAGEMENT Page 31

Flexion/extension at the craniocervical junction:

This is best assessed by asking the patient to maximally flex their neck. The examiner's hand is then placed on the back of the patient's neck to prevent movement of the cervical spine and the patient is asked to nod their head. Alternatively a pen can be held against the forehead whilst maximally flexing and extending the neck. Greater than 90° of movement should be possible. Reduced movements are associated with difficult laryngoscopy.

The thyromental distance (Patil's test):

The distance from the tip of the thyroid cartilage to the tip of the mandible, with the neck fully extended. This should be greater than 6.5 cm (three finger breadths) and estimates the potential space into which the tongue can be displaced on laryngoscopy. A distance of less than 6 cm is associated with difficult laryngoscopy and predicts 75% of difficult laryngoscopies.

The sternomental distance:

The distance from the upper border of the manubrium to the tip of the mandible with the neck fully extended. A distance of less than 12.5 cm is associated with difficult laryngoscopy in adults.

Other tests:

Radiographs of mandibular length and depth have been used to predict difficult intubation. These are time consuming and are probably no better than the above clinical tests.

AIRWAY ASSESSMENT

AIRWAY MANAGEMENT Page 32

With cervical spine disease (e.g. ankylosing spondylitis, rheumatoid arthritis, Klippel—Feil abnormality) flexion/extension views are useful to determine the stability of the odontoid peg, the mobility of the atlantoaxial—occipital complex and the presence of fracture dislocations. Patients with disease that involves the atlantoaxial-occipito complex have a higher prevalence of difficult laryngoscopy than those with disease below C2.

Adults with a partially obstructed airway may, if time allows, be investigated with CT scanning. The scan will show the site of the lesion, the dimensions of the trachea, the relationship of the lesion to the carina and in the case of malignancies, whether or not the tracheal wall has been invaded.

Successful airway management is dependent on careful patient assessment. If there is a high likelihood that mask ventilation and/or direct laryngoscopy will be difficult, consideration should be given to securing the airway with the patient awake.

AIRWAY MANAGEMENT Page 33

Failure to maintain a patent airway in the unconscious patient will result in death from asphyxiation.28 Remember to protect the cervical spine if injury is suspected, however the airway always takes precedence over any injury including spinal. Assess airway patency and air exchange.

Look for:

Tongue obstruction Loose teeth

Foreign bodies

Facial and oral bleeding Vomitus

Listen for:

Air movement at nose, mouth and lung fields

Inspect oropharynx for:

Foreign objects causing obstruction

Observe for:

Intercostal and supra clavicular muscle retractions

Manual airway clearance:

Position patient on side using gravity to assist drainage Open mouth and visually check – remove foreign objects Perform airway clearance manoeuvre as indicated

AIRWAY MANAGEMENT

Airway patency may be impaired by the loss of normal muscle tone or by obstruction. In the unconscious patient relaxation of the tongue, neck and pharyngeal muscles causes soft tissue obstruction of the supraglottic airway. This may be corrected by simple manual airway clearance procedures like;

and suction.

(1) Chin lift

Use: It provides an open airway when patient lying on side or on back during Expired Air

Resuscitation (EAR).

Technique: Support the jaw at the point of the chin in such a way that there is no

pressure on the soft tissues of t

this assists in opening of the airway. The chin is supported at the point by the knuckle of the middle finger, with the little and ring fingers clear of the soft tissues of the neck. The index finger lies along the line of the jaw. The thumb is placed along the front of the lower jaw between the lower lip and point of the chin and is used to open the mouth slightly. This manoeuvre should not hyperextend the neck. This is useful for trauma patients by not compromising the cervical spine.

OPENING OF AIRWAY

Airway patency may be impaired by the loss of normal muscle tone or by obstruction. In unconscious patient relaxation of the tongue, neck and pharyngeal muscles causes soft tissue obstruction of the supraglottic airway. This may be corrected by simple manual airway clearance procedures like; chin left, jaw thrust, cervical spine considerati

It provides an open airway when patient lying on side or on back during Expired Air

Support the jaw at the point of the chin in such a way that there is no pressure on the soft tissues of the neck. Because the tongue is attached to the lower jaw, this assists in opening of the airway. The chin is supported at the point by the knuckle of the middle finger, with the little and ring fingers clear of the soft tissues of the neck. The r lies along the line of the jaw. The thumb is placed along the front of the lower jaw between the lower lip and point of the chin and is used to open the mouth slightly. This manoeuvre should not hyperextend the neck. This is useful for trauma

not compromising the cervical spine.22, 29

Chin lift

OPENING OF AIRWAYS

Page 34

Airway patency may be impaired by the loss of normal muscle tone or by obstruction. In unconscious patient relaxation of the tongue, neck and pharyngeal muscles causes soft tissue obstruction of the supraglottic airway. This may be corrected by simple manual

chin left, jaw thrust, cervical spine consideration

It provides an open airway when patient lying on side or on back during Expired Air

Support the jaw at the point of the chin in such a way that there is no he neck. Because the tongue is attached to the lower jaw, this assists in opening of the airway. The chin is supported at the point by the knuckle of the middle finger, with the little and ring fingers clear of the soft tissues of the neck. The r lies along the line of the jaw. The thumb is placed along the front of the lower jaw between the lower lip and point of the chin and is used to open the mouth slightly. This manoeuvre should not hyperextend the neck. This is useful for trauma

AIRWAY MANAGEMENT (2) Jaw Thrust

Use: It provides an open airway when patient lying on side or on back during EAR as an

alternative to head tilt or chin lift.

Technique: In jaw thrust procedure position of

operator’s 3rd, 4th and 5th fingers is around the angle of the mandible while index fingers are placed on the body of the mandible and thumbs are placed over the zygoma bilaterally. Then apply pressure with the

bend in the jaw just below the ear) to thrust the jaw forward along with backward head tilt is used to opens the airway. Used with face mask on a bag

good seal and adequate ventila

Check for signs of breathing:

Look for rise and fall of the chest Listen for air movement

Feel for air movement at the mouth and/or nose

It provides an open airway when patient lying on side or on back during EAR as an alternative to head tilt or chin lift.

In jaw thrust procedure position of operator at the top of the head. Position of operator’s 3rd, 4th and 5th fingers is around the angle of the mandible while index fingers are placed on the body of the mandible and thumbs are placed over the zygoma bilaterally. Then apply pressure with the fingers behind the angles of the jaw (the sharp bend in the jaw just below the ear) to thrust the jaw forward along with backward head tilt is used to opens the airway. Used with face mask on a bag-valve device assists with a good seal and adequate ventilation.22

Check for signs of breathing:

Look for rise and fall of the chest Listen for air movement

Feel for air movement at the mouth and/or nose

Jaw Thrust

Page 35

It provides an open airway when patient lying on side or on back during EAR as an

operator at the top of the head. Position of operator’s 3rd, 4th and 5th fingers is around the angle of the mandible while index fingers are placed on the body of the mandible and thumbs are placed over the zygoma fingers behind the angles of the jaw (the sharp bend in the jaw just below the ear) to thrust the jaw forward along with backward head tilt valve device assists with a

OPENING OF AIRWAYS

AIRWAY MANAGEMENT Page 36

(3) CERVICAL SPINE CONSIDERATIONS

Remember - the airway is more important than cervical spine

Stabilise cervical spine if trauma or concern regarding the neck; Manage patient in supine aligned position

Rigid collar, head support, tape

Rigid collar should stay in place until C spine ‘cleared’ Unable to ‘clear’ the c-spine without X-ray/CT if

GCS < 15 Patient intubated

Affected by drugs or alcohol Painful distracting injuries Don’t forget pressure care

AIRWAY MANAGEMENT Page 37 (4) SUCTION

Equipment for suction clearance of the oropharynx is essential for the provision of life support. Yankauer sucker (for mouth) Y-suction catheter (for naso and oropharynx)29:

Attach to suction tubing

Position conveniently near patients head Turn on control device

Open patient’s mouth and insert sucker into lower corner of mouth gently

Occlude control hole for no greater than 5 seconds whilst withdrawing sucker

Move tip of sucker within the oral cavity gently to remove secretions and foreign objects as required

Repeat as required

Remember:

Excessive suctioning may traumatise airway mucosa Hypoxia may result from prolonged suctioning

Suctioning may cause coughing, gagging and vomiting, all of which may raise intracranial pressure.

Suctioning may stimulate the vagus nerve, leading to bradycardia and hypotension.

ARTIFICIAL AIRWAYS

AIRWAY MANAGEMENT Page 38

If simple manual airway clearance procedures are not effective, then switch to artificial airways to maintain adequate airway. Artificial airways are as follows:

(1) Oropharyngeal airway (2) Nasopharyngeal airway

(3) Ventilation (pocket) masks airway (4) Bag – valve – masks airway

(5) Laryngeal mask airway

(6) Criciod pressure (Sellick’s manoeuvre) airway

(1).Oropharyngeal airway:

Use: This is one of the simplest artificial airways designed to prevent the tongue from

obstructing the airway by falling back against the posterior pharyngeal wall. This airway may also prevent teeth clenching.

Insertion: Oropharyngeal tube is measure from the earlobe to the corner of the mouth. If

the airway is too long it may compress the epiglottis against the laryngeal opening causing complete airway obstruction. If the airway is too short it may impact on the tongue posteriorly and cause further airway obstruction. After selection of appropriate tube lubricate it with water or patients saliva then inserted into the mouth behind the tongue and hold by the flange. Insert the tip at the side of the mouth, aiming the concave tip at the ear then rotate 90 degrees over the tongue and advance until fully inserted. In children, use tongue blade to depress tongue and insert airway over tongue –do not push tongue backward as it may obstruct the airway. Insert until flange rests against patients lips (check to ensure lower lip is not pinched between teeth and airway). Not indicated in cases conscious patient because it causes gagging, vomiting, aspiration.22

AIRWAY MANAGEMENT (2). Nasopharyngeal airway

Use: This airway provides airway patency similar to that in a correctly performed chin lift

manoeuvre. This airway may be better tolerated, than the oropharyngeal airway, in the semi conscious patient. It is useful in the patien

(trismus).

Insertion: Nasopharyngeal tube is measure from corner of nose to earlobe and its

diameter should be slightly smaller than nostril opening. Before inserting tube inspect nostrils for any obstruction then lubricate t

finally insert into a nostril that looks clear and is the wider. Gently advance, directing the tip along the floor of the nose toward the nasopharynx (90degrees to patients face) and if resistance felt - STOP –

anticlockwise 45 degrees whilst advancing. If further resistance felt, withdraw, relubricate and try other nostril or a smaller size tube. The flared external end should sit in the nasal orifice when in final position; tip may be seen in the posterior oropharynx. It provide better tolerated in responsive patient, less likely to induce vomiting. Precaution taken during suspected base of skull fracture or facial fractures. May be used to assist suctioning by passing an appropriate suction catheter down the airway

(2). Nasopharyngeal airway

This airway provides airway patency similar to that in a correctly performed chin lift manoeuvre. This airway may be better tolerated, than the oropharyngeal airway, in the semi conscious patient. It is useful in the patient whose mouth cannot be opened

Nasopharyngeal tube is measure from corner of nose to earlobe and its diameter should be slightly smaller than nostril opening. Before inserting tube inspect nostrils for any obstruction then lubricate the airway with water or lubricating jelly and finally insert into a nostril that looks clear and is the wider. Gently advance, directing the tip along the floor of the nose toward the nasopharynx (90degrees to patients face) and if DO NOT force the tube. Tube is gently rotate clockwise and anticlockwise 45 degrees whilst advancing. If further resistance felt, withdraw, relubricate and try other nostril or a smaller size tube. The flared external end should sit in the nasal hen in final position; tip may be seen in the posterior oropharynx. It provide better tolerated in responsive patient, less likely to induce vomiting. Precaution taken during suspected base of skull fracture or facial fractures. May be used to assist

oning by passing an appropriate suction catheter down the airway.

Page 39

This airway provides airway patency similar to that in a correctly performed chin lift manoeuvre. This airway may be better tolerated, than the oropharyngeal airway, in the t whose mouth cannot be opened

Nasopharyngeal tube is measure from corner of nose to earlobe and its diameter should be slightly smaller than nostril opening. Before inserting tube inspect he airway with water or lubricating jelly and finally insert into a nostril that looks clear and is the wider. Gently advance, directing the tip along the floor of the nose toward the nasopharynx (90degrees to patients face) and if DO NOT force the tube. Tube is gently rotate clockwise and anticlockwise 45 degrees whilst advancing. If further resistance felt, withdraw, relubricate and try other nostril or a smaller size tube. The flared external end should sit in the nasal hen in final position; tip may be seen in the posterior oropharynx. It provide better tolerated in responsive patient, less likely to induce vomiting. Precaution taken during suspected base of skull fracture or facial fractures. May be used to assist

AIRWAY MANAGEMENT

(3). Ventilation (pocket) masks

Use: Is best used in conjunction with oro or naso pharyngeal airways. The mask is placed

on the patient’s nose and mouth, using two hands to gain a seal.

blown into whilst maintaining a jaw thrust manual manoeuvre. To size a face mask ensure that the top sits on the bridge of the nose and the bottom fits into the space between the lower lip and the chin.

(4). Bag-valve-mask (BVM)

Use: To provide positive pressure ventilation. Supplemental oxygen should be attached to

the bag at a flow rate of at least 12

ARTIFICIAL AIRWAYS

(3). Ventilation (pocket) masks

Is best used in conjunction with oro or naso pharyngeal airways. The mask is placed on the patient’s nose and mouth, using two hands to gain a seal. The valve of the mask is blown into whilst maintaining a jaw thrust manual manoeuvre. To size a face mask ensure that the top sits on the bridge of the nose and the bottom fits into the space between the

mask (BVM)

To provide positive pressure ventilation. Supplemental oxygen should be attached to the bag at a flow rate of at least 12-15 litres/minute.

ARTIFICIAL AIRWAYS

Page 40

Is best used in conjunction with oro or naso pharyngeal airways. The mask is placed The valve of the mask is blown into whilst maintaining a jaw thrust manual manoeuvre. To size a face mask ensure that the top sits on the bridge of the nose and the bottom fits into the space between the