Show Summary Details
Page of

The larynx 

The larynx
Chapter:
The larynx
Author(s):

Rogan Corbridge

and Nicholas Steventon

DOI:
10.1093/med/9780199550791.003.12
Page of

PRINTED FROM OXFORD MEDICINE ONLINE (www.oxfordmedicine.com). © Oxford University Press, 2016. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use (for details see Privacy Policy and Legal Notice).

Subscriber: null; date: 18 December 2018

  • Structure and function of the larynx [link]

  • The vocal cords [link]

  • Congenital laryngeal lesions [link]

  • Infections of the larynx [link]

  • Cancer of the larynx [link]

  • Treatment of laryngeal cancer [link]

  • Benign lesions of the larynx [link]

  • Differential diagnosis of a hoarse voice [link]

  • Stridor [link]

  • The emergency airway [link]

  • Cricothyroidotomy [link]

  • Tracheostomy care and trache tubes [link]

Structure and function of the larynx

Structure

The larynx is a tube made up of cartilage and bone, held together by membranes, ligaments, and muscles. Above, the larynx connects with the pharynx and oral cavity; below, it connects with the trachea and major airways (The larynx see Fig. 12.1). Behind the larynx is the opening of the oesophagus.

Food and drink are guided from the mouth to the oesophagus, while air passes via the trachea to the lungs. Food passes over the back of the tongue and runs down two channels called the ‘piriform fossae’. These lie slightly behind and to the side of the larynx. They join behind the cricoid cartilage and form the oesophagus (The larynx see Fig. 12.2).

Fig. 12.2 External view of the larynx.

Fig. 12.2
External view of the larynx.

Function

The main function of the larynx is to protect the lower airways from contamination by fluids, liquids, and saliva. The way this happens is as follows: the larynx rises during swallowing, bringing the laryngeal inlet closer to the tongue base and allowing the food bolus to pass on either side. The epiglottis folds down to cover the larynx. The vocal cords and false cords (The larynx see Fig. 12.3) come together.

Fig. 12.3 Internal side view of the larynx.

Fig. 12.3
Internal side view of the larynx.

The vocal cords

Structure

The vocal cords, also called the ‘vocal folds’, and collectively called the ‘glottis’, are suspended in the airway. They divide the larynx in two—the supraglottis lies above the vocal cords and the subglottis lies below.

The cords are made of a stiff central muscle and ligament, and a soft loose cover. They are fixed to the thyroid cartilage at the front and to the arytenoid cartilages at the back. These cartilages can slide away from and towards each other, opening and closing the laryngeal inlet.

Innervation

The sensation of the supraglottis is carried by the internal branch of the superior laryngeal nerve. The external branch carries motor fibres to the cricothyroid muscle. This muscle is important in adjusting the tension of the vocal cord. The vagus nerve gives rise to the recurrent laryngeal nerve, and this in turn carries sensation to the subglottis and is motor to all the other muscles of the larynx. The left recurrent laryngeal nerve has an unusually long course and loops down into the chest, lying close to the hilum of the lung. It is prone to infiltration by tumours of this region. (The larynx See Fig. 12.8.)

Fig. 12.8 Diagram of RLN anatomy and sites of damage.

Fig. 12.8
Diagram of RLN anatomy and sites of damage.

Lymph drainage

The vocal cords are a watershed for lymphatic drainage. Above, the supraglottis drains to the pre-epiglottic and upper deep cervical nodes; below, drainage is to the lower deep cervical and pretracheal nodes. The cords have very poor lymph drainage, so tumours limited to vocal cords have a low risk of lymphatic spread. Tumours of the lymphatic-rich supra- or sub-glottis frequently present with lymph node metastases and consequently will have a worse prognosis (Fig. 12.4).

Fig. 12.4 Lymph drainage of the larynx.

Fig. 12.4
Lymph drainage of the larynx.

Function

The vocal cords are the source of the sound vibration, which we adapt with our mouth, tongue, lips, and teeth to produce speech. As air passes up between the cords the Bernoulli effect draws the mucosa of the cords together. They meet for a fraction of a second and then the pressure rises below the cords, blowing them apart again. This vibration of the cords and the distortion of the mucosa that results from it is known as the ‘mucosal wave’. This causes the voice.

Congenital laryngeal lesions

Babies are more prone to breathing difficulties because their larynx differs from an adult’s in the following ways:

  • The airway is smaller both relatively and absolutely.

  • The laryngeal mucosa is less tightly bound down and as a result may swell dramatically.

  • The cartilaginous support for the airway is less rigid than in an adult—this makes it more prone to collapse, especially during inspiration.

Laryngomalacia

Signs of this condition show themselves shortly after birth with inspiratory stridor and feeding difficulties. When breathing in, these babies experience an excessive collapse and indrawing of the supraglottic airways, leading to breathing difficulties.

Usually this condition is mild and self-limiting. When it is severe an aryepiglottoplasty may be performed. This involves dividing the excessively tight aryepiglottic folds, which allows the epiglottis to spring upwards and open up the airway.

Subglottic stenosis

This abnormality is caused by an excessively narrow cricoid cartilage. It is either a birth defect, or it arises as a result of intubation and prolonged ventilation. Subglottic cysts and haemangiomas may present with similar symptoms.

The main sign of this condition is stridor at any age from birth to 2 years. Diagnosis is made by inspecting and measuring the diameter of the subglottis under general anaesthetic. Mild cases may be treated conservatively, but more severe stenoses require surgical invervention and laryngotracheal reconstruction. The larynx See Table 12.1 for Cotton grading of stenosis.

Table 12.1 Congenital laryngeal lesions: cotton grading of tracheal stenosis

Grade 1

≤50% obstruction

Grade 2

51–70% obstruction

Grade 3

71–99% obstruction

Grade 4

No lumen

Laryngeal web

This condition occurs when the vocal cords fuse together and the airway is reduced. Fusion can be minimal, with little effect on the airway; or complete fusion can occur which is incompatible with life.

The main signs of this condition are respiratory difficulties, stridor, and a hoarse cry. Severe cases will require immediate surgical intervention, either via a tracheostomy (when an artificial breathing hole is made in the neck below the cords to bypass the obstruction) or by endoscopic division of the web.

Laryngeal cleft

This condition occurs when the posterior larynx has failed to fuse. At its most severe this will also extend down to involve the posterior wall of the trachea.

The main signs are respiratory problems associated with feeding, as a result of aspiration into the trachea. However, mild cases can be difficult to diagnose. Where there are symptoms, surgical repair may be needed.

Vocal cord palsy

The recurrent laryngeal nerves are long in children and adults, reaching from the skull base down into the chest and back up again to the larynx. Because of their length, they are prone to damage anywhere along their course. Unilateral palsy will cause a weak breathy cry and feeding difficulties as a result of aspiration, and bilateral palsy will present as marked stridor.

Infections of the larynx

Acute laryngitis

Inflammation of the larynx may occur in isolation or as part of a general infective process affecting the whole of the respiratory tract. It is very common, often presenting as a sore throat and loss of voice with a cold.

Signs and symptoms

  • Hoarse voice

  • Pain on speaking and swallowing

  • Malaise

  • Slight pyrexia

  • Examination of the vocal cords will show them to be reddened and swollen

Treatment

Most patients with acute laryngitis either self-medicate or are treated in the primary care setting with supportive therapy such as voice rest, simple analgesia, steam inhalations, and simple cough suppressants.

Voice rest is especially important for any professional voice user. Patients should be advised of this, and of the risk of haemorrhage into the vocal cord, which can produce permanent adverse effects on the voice.

Chronic laryngitis

Chronic laryngitis is a common inflammation of the larynx caused by many different factors. It often begins after an upper respiratory tract infection. Smoking, vocal abuse, chronic lung disease, sinusitis, postnasal drip, reflux, alcohol fumes, and environmental pollutants may all conspire together to maintain the inflammation.

Signs and symptoms

  • A hoarse voice.

  • A tickle in the throat or a feeling of mucus in the throat.

  • A patient who is constantly clearing their throat or coughing—this causes still more inflammation of the cords and establishes a vicious circle.

  • A laryngoscopy which reveals thickened, red, oedematous vocal cords.

The patient should be referred for a laryngeal examination if their symptoms fail to settle within 4 weeks. If any concern remains after this examination, the patient should be admitted for an examination and a biopsy, under general anaesthetic, to exclude laryngeal malignancy.

Treatment

Any agents that are causing the chronic laryngitis should be removed. The patient may require the skills of a speech therapist. Patients will also respond well to explanation and reassurance that they do not have a more serious condition.

Reinke’s oedema

This is a specific form of chronic laryngitis found in smokers. The vocal cords become extremely oedematous and filled with a thin jelly-like fluid. The oedema fails to resolve due to poor lymph drainage of the vocal cord. Stopping smoking and speech therapy are helpful in removing the causes of this condition. In many cases microlaryngeal surgery is required to incise the cord and suck out the oedema. It is important to avoid any damage to the free edge of the vocal cord when performing this operation, as it can permanently affect the mucosal wave and hence the voice.

Epiglottitis and supraglottitis

This is an inflammation of the epiglottis or supraglottic tissues that affects children and adults. Epiglottitis is now rare in children in the UK (as a result of the haemophilus influenza type b (HIB) vaccination). It is seen more often in adults, where it tends to affect the whole of the supraglottic tissues (and is called ‘supraglottitis’). Most ENT departments see one case per month in the winter.

The causative agent is usually Haemophilus influenzae.

Signs and symptoms

  • Difficulty in swallowing leading to drooling of saliva.

  • Change in the voice, described as a muffled or ‘hot potato voice’ or change in the child’s cry.

  • Dramatic swelling of the supraglottic tissues.

  • Pools of saliva seen collected around the larynx on endoscopy.

This condition should not be underestimated. It may start with features similar to any other respiratory tract infection, but it can rapidly progress to total airway obstruction within hours of onset. Consider this diagnosis early on, and get expert help.

Management

  • Admit the patient and keep them upright. Laying the patient flat could obstruct their airway.

  • Do not attempt to examine the mouth, as this may obstruct the patient’s breathing.

  • No X-rays—they do not add much to the diagnosis and remove the patient from immediate expert assistance should they need it.

  • Call for senior help—an ENT surgeon and an anaesthetist.

Treatment

If epiglottitis or supraglottitis is suspected, stop further investigations. Escort the patient calmly and quickly to an operating theatre where an experienced paediatric anaesthetist and scrubbed consultant ENT surgeon are standing by with the appropriate equipment (laryngoscope, ventilating bronchoscope, and tracheostomy set).

Where possible, the patient should be intubated and treated with the appropriate antibiotics. However, oral intubation may be difficult and the ENT surgeon may be asked to secure the airway surgically.

Croup

This infection is common in children. It affects the whole of the upper respiratory tract (URT), hence the more descriptive name, ‘acute laryngotracheobronchitis’. It is usually viral in origin, but a bacterial infection with H. influenzae is sometimes seen. The speed of onset of croup is slower than in epiglottitis, but it can be extremely serious and even life-threatening.

Signs and symptoms

  • Mild preceding upper respiratory tract infection

  • Rising pyrexia

  • Stridor

  • Malaise

Treatment

  • Admission to hospital may be necessary in all but the most minor cases

  • Intravenous antibiotics

  • Nebulized adrenaline

  • Ventilatory support where required

Cancer of the larynx

The vast majority of laryngeal cancers are squamous cell carcinomas. Smoking is the risk factor for laryngeal cancer, although smoking and drinking in combination puts the patient at even more risk. It is the most common neck and head malignancy.

Since the whole of the upper aerodigestive tract has been exposed to the same risk factor (that is, smoke), there is a widespread field change throughout this mucosa. These patients therefore have an increased risk of developing another cancer in the mouth, pharynx, larynx, or oesophagus. Some 5% of patients with one head and neck cancer will present with a second primary tumour elsewhere in the head or neck. This may be silent and cause no symptoms at all!

Signs and symptoms

The patient’s symptoms will depend upon which site(s) within the larynx is affected. A tumour on the vocal cord will cause a hoarse voice, and a patient in this situation will usually present early. However, a tumour in the supraglottis may present few symptoms until much later and a patient may present with advanced disease. All patients with a lump in the neck must be referred for an ENT examination.

Signs of advanced laryngeal cancer are:

  • Pain—often referred to the ear

  • Voice change—the voice is muffled rather than hoarse, unless the tumour also extends to involve the true vocal cords

  • Breathing difficulties and stridor

  • Difficulty swallowing or inhaling

  • Lymph node enlargement in the neck—this is often the only presenting feature

Investigations

Although a clinical diagnosis can often be made after examination of the larynx, a biopsy is essential. This is because conditions such as laryngeal papillomas, granulomas, and polyps may mimic laryngeal cancer. All patients should also undergo examination of the whole of the upper aerodigestive tract (panendoscopy) to check for a second primary tumour.

All patients must have at least a CXR. A CT scan of the chest is routine practice in many centres. CT/MRI scanning of the neck is also mandatory, particularly looking for thyroid cartilage erosion and enlarged lymph nodes in the deep cervical chain.

Staging

TNM staging is applied to head and neck cancers in a similar way to other sites (The larynx see Boxes 12.1–12.3):

  • The T stage is determined by the anatomical site/sites affected.

  • The N stage refers to the local nodal spread.

  • The M stage is determined by the presence or absence of distant metastases.

Treatment of laryngeal cancer

Treatment is with surgery or external beam radiotherapy. Early laryngeal tumours are satisfying to treat, since more than 90% can be cured.

If a patient is too unfit to undergo radical treatment, palliative radiotherapy or chemotherapy may be used to shrink the tumour. This can reduce symptoms and improve the patient’s quality of life.

Although practice does vary slightly between different units and countries, in general, treatment is as follows:

  • Small tumours (stage T1 and T2) are treated with radiotherapy—surgery is used only if they recur afterwards.

  • Big tumours (stage T4) are treated with radical excision—a partial or total laryngectomy.

  • The treatment of T3 tumours is controversial—some opt for primary surgery and others advocate radiotherapy, holding surgery in reserve for radiation failures.

Each patient should be assessed individually and treatment decisions must be made in a multidisciplinary team setting, with the knowledge and consent of the patient.

Surgery for laryngeal cancer

The decision as to which type of surgery is performed largely depends on the size and extent of the tumour. Surgery may either be performed endoluminally—with endoscopes from the inside—usually with the aid of a laser, or the radical excision of part of, or the entire, larynx may be needed. In general, smaller tumours (T1 and T2) are more easily treated with endoscopic laser surgery, and patients with larger T3 and 4 tumours are offered radical excisional surgery. (The larynx See ‘Laryngectomy’, p. [link].)

Radical radiotherapy for laryngeal cancer (Box 12.4)

A total dose of 50–70Gy is given over 4–6 weeks, Monday to Friday.

Each treatment only lasts a few minutes but the patient has to wear a custom-made Perspex mask, rather like a neck brace. This holds the patient in exactly the same position each day, ensuring that the radiotherapy fields are directed accurately onto the tumour and immediate area. This spares the uninvolved areas of the head and neck.

Towards the end of treatment the patient will suffer with painful mucositis. Swallowing can become difficult, and the patient may need to be admitted for enteral feeding and analgesia.

Laryngectomy

Several different types of partial laryngectomy have been described. These are collectively known as ‘less than total’ and are beyond the scope of this book.

Total laryngectomy

This was first described at the beginning of the last century, but it remains a reliable and effective treatment. During a total laryngectomy the larynx is removed and the trachea is brought to the skin as an end-stoma in the neck. The pharynx is opened and repaired to reconstitute the swallowing mechanism (Fig. 12.5). A neck dissection is often performed in combination with this procedure. This is because patients with advanced or recurrent laryngeal disease are at considerable risk of having nodal metastases, which may either be palpable or hidden.

Fig. 12.5 Diagram of pre- and postlaryngectomy anatomy.

Fig. 12.5
Diagram of pre- and postlaryngectomy anatomy.

Voice restoration after laryngectomy

(The larynx see also ‘Speech and language therapists’, p. [link].)

Oesophageal speech (The larynx see Fig. 12.6a)

In those who can achieve it, oesophageal speech offers near-normal verbal communication. The basic principle is that air is swallowed into the stomach and then regurgitated into the pharynx. This causes vibration of the pharyngo-oesophageal segment (PE segment) similar to a belch. This can be modified with the lips and teeth into intelligible speech.

The main problem is that not all patients can manage to achieve this type of speech, and even if they do, only small amounts of air can be swallowed. This means that the resultant speech can only be made up of short phrases at best.

Tracheo-oesophageal puncture (The larynx see Fig. 12.6b)

This is when artificial communication is created between the back wall of the trachea and the front wall of the pharynx/oesophagus. This is usually done at the time of the initial surgery (primary puncture) but can be performed at anytime thereafter (secondary puncture).

A one-way valve is inserted into this tract which allows the passage of air from the trachea to the oesophagus, vibrating the PE segment as above. In order to activate the valve, the patient must occlude their stoma and try to breathe out. This may be done with a finger, or by using a second manually operated valve which sits over the stoma as part of a heat and moisture exchanger (HME). The HME also filters the inhaled air and prevents excess water vapour being lost from the respiratory tract—in effect this replaces some of the functions of the nose.

Artificial larynx (Servox)

Some patients cannot achieve either of the above forms of speech, and require an external vibrating source. The vibrating end of this device is held firmly onto the patient’s neck, floor of their mouth or cheek, and this causes these tissues to vibrate. As a result, the air within the pharynx and oral cavity vibrates and sound is produced. The voice produced does sound rather unnatural but this is a simple and effective means of communication (The larynx see Fig. 12.7).

Benign lesions of the larynx

These are lesions of the vocal cords which are not cancer. Signs of a benign lesion—such as a hoarse voice—can be indistinguishable from those of laryngeal cancer. It is therefore imperative that any patient with a change in their voice lasting more that 4 weeks is referred to an ENT surgeon to exclude a laryngeal malignancy.

Vocal cord polyp/cyst

These lesions are indistinguishable histologically from each other. They usually arise spontaneously, but may be associated with previous laryngeal inflammation. Symptoms are a sore throat and/or a hoarse voice.

The cysts are intracordal, whereas polyps are pedunculated and may be difficult to see because they sometimes hang down on their stalk to sit below the cords. Treatment is with microsurgical excision, taking care to avoid iatrogenic damage to the free edge of the vocal cord, and hence the mucosal wave and voice.

Vocal cord granuloma

This lesion is usually unilateral and affects the posterior aspect of the vocal cord. As a result, it can have quite a minimal effect on the voice. Vocal cord granuloma arises as a result of inflammation of the arytenoid cartilage (perichondritis). It is most often seen as a result of intubation trauma or excessive coughing. The patient usually complains of pain in their larynx. Reflux is a commonly associated feature.

The lesion requires a biopsy as SCC can present with similar features. Treatment may include surgical excision, speech therapy, and the treatment of acid reflux.

Singer’s nodules

These nodules—also known as ‘screamers’ nodules’—occur as a result of prolonged voice abuse or misuse. They are common in children, amateur actors, and singers—they give a characteristic huskiness to the voice.

They are always bilateral and occur at the junction of the anterior one-third and posterior two-thirds of the vocal cords. Early or ‘soft’ nodules will resolve with speech therapy and good vocal habits, but long-established ‘hard’ nodules may require surgery.

Papillomata

These non-cancerous growths are most commonly seen in children, but may also occur in adults. Papillomas arise as a result of HPV (human papillomavirus) infection. The route of transmission is thought to be through inhalation. There may also be some defect in the host immune system, as some individuals are affected and others are not. Spontaneous resolution tends to occur in children around puberty, but this is less common in adults.

In its most severe form, a papilloma may result in significant airway obstruction in the larynx, trachea, and major bronchii. If the patient’s airway is obstructed, surgical debulking of the papilloma is required. Removal of every last papilloma is not advised, since this will cause scarring of the vocal cords and they often recur. A tracheostomy may be required, but even then papillomas may grow around the stoma.

Malignant transformation may occur in adults, especially with subtypes 7 and 11. Systemic treatment with interferon is effective, but rebound growth may be dramatic when it is stopped.

Muscle tension dysphonia

This is a common problem seen in general and ENT practice. Symptom is a hoarse voice which tires easily and may vary in pitch. Patients sometimes say their voice ‘cracks’ or ‘gives out’ and the quality of the voice varies from day to day and moment to moment. Occasionally the patient may present with aphonia.

These problems are caused by laryngeal muscular tension abnormalities. They are associated with voice misuse, psychological stress, and psychiatric disease.

Globus-type symptoms are frequent. These include a feeling of a lump in the throat, a feeling of mucus in the throat, and frequent throat clearing. The treatment is reassurance and explanation, with speech therapy for patients who do not respond well.

Vocal cord palsy

Palsy or paralysis of the vocal cords will mean that the patient may have a weak breathy voice rather than the harsh hoarse voice of laryngeal cancer. They will have a poor, ineffective cough and aspiration is common. (The larynx See Box 12.5.)

The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve and has a long course (The larynx see Fig. 12.8). This makes it susceptible to damage in a variety of sites.

Investigation

Remember the rule of thirds below:

  • ⅓ idiopathic

  • ⅓ surgery

  • ⅓ neoplasia

Where there is no history of recent surgery, order:

  • CXR—if it is negative proceed to:

  • CT scan—skull base to hilum

  • ± USS thyroid

  • ± oesphagoscopy

If the above are negative then postviral neuropathy is the most likely cause. The causes of vocal cord immobility (fixation rather than palsy) include rheumatoid arthritis, laryngeal trauma, prolonged intubation, and carcinoma affecting the cricoarytenoid joint. An endoscopy, together with palpation of the joint, is necessary to confirm this abnormality.

Treatment

Where there is a small gap between the cords, speech therapy may be all that is needed to strengthen the mobile cord and aid compensation. When there is a larger gap, the paralysed cord can be medialized, either by an injection technique or via a thyroplasty (The larynx see Figs 12.10 and 12.11). Poor function of the cords may lead to aspiration and chest infections. Dietary modifications, tube feeding, and even a tracheostomy may be required to protect the airway from soiling.

Neurological laryngeal conditions

Any condition which affects the brainstem (CVA, trauma, or tumour) will affect the function of the vagus nerve, and as such the recurrent laryngeal nerve. With these conditions, the voice problems may be less a cause for concern than the lack of protection of the airway, which can lead to life-threatening aspiration. Any systemic neurological or neuromuscular condition, such as multiple sclerosis or muscular dystrophy, may also affect the voice. But it is rare for these conditions to present first to an ENT surgeon as voice problems.

Differential diagnosis of a hoarse voice

Voice problems are common: the majority are due to URTI and will settle with little or simple supportive treatment. However, failure to improve should raise the suspicion of laryngeal pathology and any patient with constant hoarse voice (i.e. where the voice never returns to normal) for more than 4 week should be referred urgently to the ENT clinic for laryngoscopy in order to examine the vocal cords and exclude a laryngeal cancer or other pathology. Many patients will present with a minor and fluctuating hoarseness and here the most likely diagnosis is a muscle tension or functional dysphonia. The problem is usually well treated with a course of speech therapy. The important and common causes of vocal problems and the most typical features are shown in Table 12.2 p. [link].

Table 12.2 Common causes of dysphonia

Diagnosis

Voice quality

Duration

Special features

Treatment

Laryngeal cancer

Hoarse/gruff

Constant >4/52 progressive

Smoking historyNeck lump? Referred otalgia

RT/surgery

Vocal cord palsy

Weak/breathy

Poor ‘bovine’ cough

Constant >4/52

Smoking history.

Frequently due to lung cancer

Exclude lung cancer.

Consider thyroplasty to improve the voice

Vocal cord nodules

Husky

Usually variable

Poor singing technique, shouting, or voice abuse

Speech and language therapist (SALT), rarely surgery

Functional dysphonia

Mildly husky

Varies, i.e. periods when the voice is normal

Voice tires easily, worse in the evenings, often associated with stress/life events

SALT & reassurance

Reinke’s oedema

Gruff and deep. Women often say they sound like a man

Constant—non-progressive

Smoking history hypothyroid

Stop smoking SALT Surgery

Neurological causes

Variable, difficulty with pitch control. Often associated also with dysarthria

Variable

Other neurological signs & symptoms. Frequently also mild dysphagia

Refer to neurology SALT

Stridor

Stridor is a high-pitched noise caused by a restricted airway. It is most common in children, due to the anatomical differences between the paediatric and the adult larynx (The larynx see ‘Congenital laryngeal lesions’, p. [link]).

The timing of the stridor in respiration tells you the obstruction or restriction site:

  • Laryngeal stridor = inspiratory

  • Tracheal stridor = expiratory—a wheeze

  • Subglottic stridor = biphasic—occurs when breathing in or out

A small reduction in the diameter of the airway leads to a dramatic increase in the airway resistance and hence the work of breathing (Poiseuille’s law of resistance = r4).

Causes of stridor

Congenital

  • Laryngomalacia

  • Vocal cord web

  • Bilateral vocal cord palsy

  • Subglottic stenosis

Acquired

  • Trauma

  • Foreign body

  • Epiglottitis/supraglottitis

  • Croup

  • Carcinoma

  • Airway compression, e.g. thyroid

Assessment

Stridor is an ominous sign. Even if the patient appears to be coping, be sure that they are closely observed and that facilities to secure the airway are readily at hand. Patients may suddenly decompensate with devastating consequences.

  • Take a rapid history

  • Measure O2 saturation

  • Take temperature

  • Check respiratory rate

In children, pyrexia, drooling, dysphagia, and a rapid progression of the illness, suggests epiglottitis. Take the patient to a place of safety such as a resuscitation room or operating theatre, and call for a senior ENT surgeon and experienced anaesthetist.

A similar history in adults suggests supraglottitis. This diagnosis can usually be confirmed by a careful nasolaryngoscopy. (The larynx See also ‘The emergency airway’, p. [link].)

The emergency airway

Remember to keep calm!

The following questions should be answered first:

  • Will admission and observation be sufficient for the time being, or do you need to intervene to secure the airway?

  • If intervention is required do you need to do something now, or do you have time to wait for senior help to arrive?

Assessment

Assessment should follow three stages—Look, listen, and observe.

Look

  • What is the patient’s colour—are they blue?

  • Is there any intercostal recession or tracheal tug?

  • What is the patient’s respiratory rate?

Listen

  • Can the patient talk in sentences, phrases, words, or not at all?

  • Do they have stridor? Is it inspiratory, expiratory, or mixed?

  • What history can the patient give?

Observation

  • Is the patient’s respiratory rate climbing?

  • Is the patient feverish?

  • What is the patient’s O2 saturation? Is it falling?

Interventions

Consider the following options:

  • Oxygen via a face mask or nasal prongs

  • Broad-spectrum antibiotics, such as co-amoxiclav (check the patient is not allergic)

  • Nebulized adrenaline (1ml of 1:1000 with 1ml saline)

  • Heliox—this is a mixture of helium and oxygen that is less dense than air. It is easier to breathe, and it buys you time, during which you can take steps to stabilize the airway

Endotracheal intubation

This should be the first line of intervention where possible. If it proves difficult or impossible, move on quickly.

Tracheostomy

A surgical hole is made in the trachea below the cords. In an emergency, a longitudinal incision is made in the midline of the neck and deepened to the trachea, dividing the thyroid. Brisk bleeding is to be expected. The blade is plunged into the airway and twisted sideways to hold the tracheal fenestration open. A cuffed tracheostomy or ET tube is inserted into the airway and the bleeding thyroid is dealt with afterwards.

Cricothyroidotomy

The larynx See Fig. 12.13.

Fig. 12.13 Diagram of tracheostomy tubes. (a) Cuffed fenestrated tube; () non–cuffed, non-fenestrated tube; (c) paediatric tube.

Fig. 12.13
Diagram of tracheostomy tubes. (a) Cuffed fenestrated tube; () non–cuffed, non-fenestrated tube; (c) paediatric tube.

Indications

Upper airway obstruction when endotracheal intubation is not possible, e.g. irretrievable foreign body, facial oedema (burns, angio-oedema), maxillofacial trauma, infection (epiglottitis).

Procedure

  • Lie the patient supine with their neck extended.

  • Run your index finger down the neck anteriorly in the midline. First you will find the notch in the upper border of the thyroid cartilage (the Adam’s apple). Just below this you will come to a depression—the cricothyroid membrane which feels slightly spongy. It lies just above the prominence of the cricoid cartilage.

NB: Needle and Mini-Trach® are temporary measures pending formal tracheostomy.

1 Emergency needle cricothyroidotomy:

  • Pierce the membrane with a large-bore cannula (14G) attached to a syringe: withdrawal of air confirms position; lidocaine may or may not be required).

  • Advance the cannula at 45° to the skin superiorly in the sagittal plane.

  • Use a Y-connector or improvised connection to the O2 supply at 15L/min: use your thumb on the Y-connector to allow O2 in over 1s and CO2 out over 4s (‘transtracheal jet insufflation’). This is the preferred method in children <12yrs. However, this will only sustain life for 30–45min before CO2 builds up.

2 Mini-Trach II®:

  • This contains a guarded blade, introducer, 4mm uncuffed tube (slide over introducer) with ISO connection and binding tape.

  • The patient will have to be ventilated via a bag, as the resistance is too high to breathe spontaneously.

  • This will sustain life for 30–45min.

3 Surgical cricothyroidotomy:

  • Smallest tube for prolonged ventilation is 6mm.

  • Introduce high-volume, low-pressure cuff tracheostomy tube through a horizontal incision in the membrane. Take care not to cut the cricoid cartilage.

Complications

  • Local haemorrhage

  • Aspiration

  • Posterior perforation of the trachea ± oesophagus

  • Subglottic stenosis if the cricoid is damaged

  • Tube blockage

  • Tube misplacement due to anterior subcutaneous tunnelling

Further reading

This section is substantially based on the advice to be found in the Oxford Handbook of Clinical Medicine, 7th edition, Oxford University Press, and is used with thanks.

Tracheostomy care and trache tubes

Tracheostomy operation

In an elective tracheostomy, the incision is usually placed horizontally. The strap muscles are separated in the midline, and the thyroid isthmus is carefully divided and oversewn. The trachea is opened at the 3rd or 4th tracheal ring, and a window of tracheal cartilage is removed. A tracheostomy tube of the right size (three-quarters of the diameter of the trachea) is inserted and the cuff is inflated.

Tracheostomy tubes (The larynx See Figs 12.13 and 12.14.)

The choice of tubes may seem bewildering, but the basic principles are as follows:

Trache tubes with inner tubes

The inner tube is slightly longer than the outer, and crusting tends to occur at the distal end and on the inner tube. The inner tube can easily be removed, cleaned, and replaced without removing the outer tube. Any patient who is likely to require a tracheostomy for more than 1 week is probably best fitted with a trache tube with an inner.

Cuffed and non-cuffed tubes

The cuff, as in an endotracheal tube, is high volume and low pressure. This prevents damage to the tracheal wall. The cuff prevents fluid and saliva leaking around the tube and into the lungs. In addition, it makes an airtight seal between the tube and the trachea, so allowing for positive pressure ventilation. Most tubes are cuffed, but when a tracheostomy is in place long term, a non-cuffed tube may be used to prevent damage to the trachea.

Metal tubes

Metal tubes are non-cuffed and are used only for patients with permanent tracheostomies. They have the advantage of being inert and ‘speaking valves’ can be inserted.

Fenestrated tubes

Most tubes are non-fenestrated. The advantage of a fenestrated tube (one with a hole in its side wall) is that air can pass through the fenestration, through the vocal cords, and enable the patient to talk. The disadvantage is that saliva and liquids may penetrate through the fenestration into the lower respiratory tree.

Post-tracheostomy care

In the first few days after a tracheostomy operation, special care needs to be taken. The patient should be nursed by staff familiar with tracheostomy care. The patient should be given a pad and pencil with which to communicate.

Precautions

  • The tube should be secured with tapes, and knotted at the side of the neck until a tract is well established.

  • The tapes should be tied with the neck slightly flexed.

  • Cuff should not be over-inflated—to prevent ischaemic damage to the tracheal wall. Use a pressure gauge to check the cuff’s pressure.

  • The patient must be given humidification for at least the first 48h to reduce tracheal crusting.

  • Regular suctioning of the airway to clear secretions may be needed.

  • A spare tracheostomy tube and an introducer should be kept by the patient’s bed in case of accidental displacement of the tube.

  • Tracheal dilators should also be close by for the same reason.

Fig. 12.14 Diagram of tracheostomy tube position (note fenestration).

Fig. 12.14
Diagram of tracheostomy tube position (note fenestration).