1

What are the principles of cervical mediastinoscopy (Figure 1)?

The procedure is performed under general anaesthesia with muscle relaxation and often with intravenous access in the lower limbs, in case of major haemorrhage.

The use of a videomediastinoscope provides excellent, safe visualisation and facilitates training.

The patient is placed supine with the neck slightly extended and a roll below the shoulders.

The neck and anterior chest are prepared, in case immediate access for sternotomy is required.

The head is draped to allow the operating surgeon to stand at the top of the table.

A 2-3cm horizontal skin incision is made 1-2cm above the jugular notch (Figure 1A).

Following incision into platysma, the vertical midline raphe between the strap muscles is divided to expose the trachea below (Figure 1B).

Blunt dissection, using a finger or mediastinoscope, is then continued along the pretracheal plane to a level just above the carina, where the pulsation of the aortic arch is palpable anteriorly (Figure 1C).

Identification of the carina provides a landmark from which the position of major vascular structures can be obtained.

The recurrent laryngeal nerve on the left must be carefully preserved.

Blunt dissection of lymph node stations 2 and 4 bilaterally, and station 7 is undertaken with the suction device. Once clearly identified and mobilised, the lymph nodes are biopsied.

Following haemostasis, local anaesthetic is instilled and the strap muscles, platysma and skin are closed with fine absorbable sutures.

Minor bleeding, if encountered, can usually be controlled by simple pressure. Diathermy is useful but should be avoided near the recurrent laryngeal nerves.

Although major bleeding is rare, if it occurs, visibility can be lost very quickly, as the mediastinoscope fills with blood.

Immediate management is to pack the wound with gauze swabs, which can control small injuries. If not, clarify where the bleeding is coming from (azygos vein, superior vena cava, pulmonary artery or other), repack to minimise blood loss and open the chest to control the injury.

A right thoracotomy will provide access to most injuries, while a sternotomy can provide access to the more proximal injuries, such as the innominate artery or vein.

2

What structures are at risk during a cervical mediastinoscopy (Figure 2)?

Innominate artery and aortic arch – which can be palpated anteriorly, whilst passing in the pretracheal plane.

Main pulmonary artery – which is located just beyond the tracheal bifurcation.

Left recurrent laryngeal nerve – which runs close to the trachea.

Azygos vein and superior vena cava – which are visible just proximal to the origin of the right main bronchus.

Pleural membranes – which can be breached laterally, particularly in thin patients.

Oesophagus – which may be encountered when obtaining biopsies of deep subcarinal lymph nodes (station 7).

3

What are the alternatives to mediastinoscopy for mediastinal lymph node sampling (Figure 3)?

Transoesophageal endoscopic ultrasound (EUS) – which can provide fine needle aspiration (FNA) samples for the posterior lymph node stations (7, 8, 9).

Endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) – which uses a convex ultrasound probe mounted on a fibreoptic bronchoscope to obtain FNA samples. Lymph node stations 2, 4, 7 and 10 (and occasionally station 5) are accessible.

The sensitivity and specificity of EUS and EBUS for lung cancer staging are similar to mediastinoscopy but with a significantly lower risk of major bleeding and other injury.

4

What are the principles of an anterior mediastinotomy (Figure 4)?

An anterior mediastinotomy, which is also known as the Chamberlain procedure, is a minimal access procedure to biopsy masses in the anterior mediastinum, including lymph node stations 5 and 6.

The patient is placed supine.

A 4-5cm incision is made in the 2nd intercostal space, 2-3cm lateral to the sternal margin. The exact position should be made with reference to a recent thoracic computed tomography (CT) scan.

The 2nd intercostal muscle is divided on the superior edge of the 3rd rib, taking care to avoid the:

a)

intercostal neurovascular bundle – which runs on the inferior margin of the 2nd rib;

b)

internal thoracic vessels – which run 1cm lateral to the costal margin.

Excision of part of the rib is not usually required.

The mediastinal fat is dissected until the lymph node or mass is identified.

A mediastinoscope can be used to help visualisation.

Although opening the pleura is common, care should be taken to avoid injury to the great vessels or phrenic nerves.

A small chest drain can be sited at the end of the procedure.

Video-assisted thoracoscopic surgery (VATS) techniques now offer an alternative approach, particularly for access to lymph node stations 5 and 6, with the potential benefit of improved visualisation, inspection of the pleura and smaller scars.

5

What are the principles of a thymectomy (Figure 5)?

Thymectomy can be performed via a:

a)

sternotomy;

b)

transcervical incision – often with thoracoscopic assistance to better visualise the inferior poles of the thymus;

c)

video-assisted thoracoscopic surgery (VATS) – which is possible from both the left and right.

Superiorly, the upper parts of the thymus extend above the innominate vein and are usually ligated at the base of the neck.

Inferiorly, all tissue between the phrenic nerves anterior to the pericardium is excised.

Accessory thymic tissue is occasionally encountered in the fat pads anterior to the pericardium, which is also excised.

6

Which structures are at risk during a thymectomy (Figure 6)?

Thymic veins – which may be avulsed from the innominate vein and require conversion from a minimal access approach.

Phrenic nerve – which may be injured on either side, especially in minimal access thymic surgery. A contralateral thoracoscope port can be used to directly visualise the phrenic nerve.

Superior vena cava and azygos vein (uncommon).

7

What are the important considerations prior to an open tracheostomy?

Clear communication with the anaesthetic team is essential, as there is a joint responsibility for the airway.

If very high ventilator support (FiO₂ >0.7 or high peak airway pressures) is required, the patient may not tolerate the brief loss of ventilation and positive end-expiratory pressure (PEEP) that is necessary during tube change.

Endotracheal (ET) tube dislodgement prior to placement of the tracheostomy tube may require immediate reintubation.

In cases of difficult intubation, the use of a fibreoptic bronchoscope is invaluable.

Previous surgery, including mediastinoscopy or oesophageal mobilisation, and fixed flexion deformities of the cervical spine may limit access.

The size of the ET tube, as well as patency and competency of the cuff, should be checked by inflation before opening the trachea.

Tracheal suction catheters and a flexible bronchoscope should be readily available.

8

What are the principal steps in an open tracheostomy (Figure 7)?

The patient is placed supine and the neck extended, with the drapes positioned to expose from the chin to the manubrium.

A 4cm transverse skin incision is made midway between the cricoid cartilage and the suprasternal notch.

Meticulous haemostasis prevents contamination of the airway with blood.

Following incision of platysma, the vertical midline raphe between the strap muscles is divided to expose the trachea below (Figure 7A).

Any subthyroid veins obstructing the view are ligated (Figure 7B).

The thyroid isthmus is ligated and divided, allowing the soft tissues to be retracted laterally (Figure 7C).

The spaces between the 2nd and 4th tracheal rings are identified, as an incision above or below these can cause a subglottic stenosis or tracheo-innominate fistula, respectively.

The ET tube is then drawn back to just below the vocal cords and a transverse incision is opened between the rings. An alternative is to make an inverted C-shaped incision to create a flap (Figure 7D).

The lubricated tracheostomy tube can then be inserted and the cuff inflated (Figure 7E).

It is important to avoid over-inflation of the cuff, as this may cause late tracheal stenosis.

The lateral ends of the incision are sutured and the tracheostomy tube is secured, either with a tracheostomy tape or by direct suture to the skin.

Suction via the tracheostomy tube helps to remove any blood or clots from the airway.

It is important to ensure correct positioning of the tracheostomy tube into the trachea (as opposed to the pretracheal plane or oesophagus). Failed intubation can be detected by checking the end-tidal CO₂ and appropriate chest excursion. A flexible bronchoscope can also be passed via the tracheostomy tube to visualise the trachea and suction any blood or secretions. Hypoxia is a very late sign of failed intubation.

9

What are the important considerations prior to a rigid bronchoscopy?

Rigid bronchoscopy is an essential skill for thoracic surgeons, as it can secure a tenuous airway and greatly facilitates interventional bronchoscopy.

A clear plan should be agreed before starting the procedure and should be communicated with the anaesthetic team.

Pre-operative checks should include:

a)

review of recent computed tomography (CT) scans;

b)

review of previous bronchoscopy reports;

c)

assessment of dentition and mouth opening.

All necessary equipment to secure the airway and perform the procedure should be readily available, including:

a)

rigid bronchoscope (Figure 8). An 8.5mm diameter scope is usually suitable for most adults, although a larger scope may be required for interventional procedures;

b)

Sanders jet ventilator;

c)

0° and 90° bronchoscopy telescopes;

d)

light source and camera stack;

e)

rigid suction catheter;

f)

endobronchial forceps to remove foreign bodies or tumours;

g)

diathermy, noradrenaline-soaked pledgets or endobronchial laser, if bleeding is anticipated;

h)

variety of endobronchial stents, if stenting is anticipated.

10

What are the principles of rigid bronchoscopy (Figure 9)?

The patient is placed supine with the neck slightly flexed (not extended), using a pillow, and the jaw slightly forwards.

One fingertip is placed on the hard palate and the bronchoscope is pivoted on the operator’s thumb, keeping the scope in the midline.

It is important to protect the superior incisors and lip, as they are at risk of injury from the bronchoscope.

There are three basic views to achieve whilst passing the rigid bronchoscope:

a)

by lifting the tongue forwards, the epiglottis can be visualised anteriorly;

b)

by gently lifting the epiglottis using the tip of the bronchoscope, the vocal cords become visible as two vertical white ‘curtains’ (Figure 9A);

c)

by rotating the scope 90° clockwise or counter-clockwise, the scope tip is passed between the vocal cords to enter the trachea, where the tracheal rings can be visualised anteriorly and the longitudinal trachealis muscle fibres visualised posteriorly (Figure 9B).

Access to the left main bronchus can be facilitated by rotating the patient’s head gently to the right, which brings the trachea and left main bronchus almost into alignment.

11

Describe the important landmarks visualised at bronchoscopy (Figures 10 and 11)

A routine diagnostic bronchoscopy should visualise the entire proximal airways from the vocal cords to at least the segmental orifices distally.

Carina – which lies at the distal end of the trachea and can be identified as a sharp vertical ridge. Widening of the carina may indicate underlying subcarinal lymphadenopathy.

Right main bronchus (RMB) – which is almost in line with the trachea and is short.

Right upper lobe (RUL) bronchial orifice – which comes off just distal to the carina on the lateral bronchial wall at 90° to the RMB and is visualised with the 90° telescope at rigid bronchoscopy. It trifurcates early into the segmental bronchial orifices, which appear like the ‘leaves of a clover’:

a)

apical segmental bronchus;

b)

anterior segmental bronchus;

c)

posterior segmental bronchus.

Bronchus intermedius – which is the continuation of the RMB beyond the origin of the RUL. After 2-3cm, it trifurcates into three orifices for the:

a)

right middle lobe (RML) bronchus – which is the most anterior;

b)

common basal trunk – which is in the middle and gives off the four right lower lobe (RLL) basal segmental bronchi;

d)

apical RLL segmental bronchus – which is the most posterior.

Left main bronchus (LMB) – which is much longer (4-6cm) than the RMB, sits at an angle to the trachea and divides into the two lobar bronchi.

Left upper lobe (LUL) bronchus – which gives off the two lingula segmental orifices early, before curving upwards to the superior three segmental orifices of the LUL.

Left lower lobe (LLL) bronchus – which continues inferiorly and gives off the:

a)

apical segmental bronchus;

b)

common basal trunk – which divides into the three LLL basal segmental bronchi.

12

What techniques are available to debride an airway tumour?

A rigid bronchoscope and large biopsy forceps can be used to debulk central airway tumours.

Laser can be used with good effect, with its cutting and coagulation properties. An example is neodymium-doped yttrium aluminium garnet (Nd-YAG, wavelength 1064nm) laser.

Airway stents may be used if the stenosis is likely to recur.

Equipment to control airway haemorrhage must also be available, including:

a)

rigid suction catheters – which are also used to remove debris and secretions;

b)

diathermy;

c)

noradrenaline-soaked pledgets.

13

What are the principles of tracheobronchial stenting?

The rigid bronchoscope is passed through the vocal cords, allowing the tumour or stenosis to be inspected.

If the lesion is distal to the carina, the patency of the contralateral (normal) bronchial tree is checked first.

Endobronchial tumours are usually debulked under direct vision using biopsy forceps, diathermy or laser, and samples are sent for histopathological analysis.

During the debulking procedure, it is important to remain within the lumen of the airway and avoid damage to any neighbouring structures.

The size of the stent is chosen according to the airway dimensions measured on the CT scan, with two different types of stent available, including:

a)

self-expandable metallic stents (such as Ultraflex™, Boston Scientific, Boston, MA) – which are commonly used for malignant obstruction. These can be either covered or uncovered;

b)

non-metallic stents – which are often made of silastic rubber, for example, the Dumon^® stent (Novatech, France). They are held in place by their natural elasticity and external studs that grip the airway wall. They are easier to remove than metallic stents, as they resist overgrowth by granulation tissue.

Image intensifier control can help direct guidewire placement and stent deployment.

The stent is opened and deployed under direct vision, with patency immediately confirmed visually (Figure 12). The stent can be moved using endobronchial forceps, if required.

Any residual blood, secretions or debris are suctioned from the airway before removing the bronchoscope.

14

What are the potential complications of airway stenting?

Displacement of the stent, with possible airway obstruction.

Haemoptysis.

Sputum retention and subsequent respiratory tract infection, due to poor transit of secretions across the stent.

Halitosis, secondary to bacterial colonisation of the stent.

Cough, due to local irritation.

Recurrent airway obstruction, especially at the proximal and distal ends of the stent, secondary to reactive granulation tissue or tumour progression. Once this has occurred, the stent can be difficult to remove.

Vascular injury, due to erosion of the metal stent into vascular structures. In view of this, the use of metal stents for benign disease is contraindicated.

15

What approaches are available for tracheal resection?

Anterior cervical collar incision – which can be used for resections of the superior third of the trachea and avoids the pain of a thoracotomy.

Right thoracotomy – which can be used for resection of the inferior third of the trachea and carina.

Cervical incision with a superior sternal split – which can be used for lesions in the middle third of the trachea

16

What are the principles of tracheal resection?

A recent CT of the thorax and neck is reviewed, as well as pre- and intra-operative bronchoscopy.

Distal ventilation is required during the surgery and can be achieved by:

a)

placing a small endotracheal tube with the balloon inflated distal to the operated area; or

b)

cross-table ventilation – where a tracheostomy or standard ET tube is placed in the distal airway and ventilated using sterile ventilator tubing in the operative field.

Mobilisation of the trachea anteriorly and posteriorly aids construction of a tension-free anastomosis.

A release procedure may also be required for longer segment resections, including:

a)

right hilar release – which involves division of the pericardium around the right pulmonary veins;

b)

suprahyoid release – which involves division of the suprahyoid muscles from the hyoid bone.

Before dividing the airway, the distal end is secured with stay sutures to avoid retraction into the mediastinum.

The anastomosis is performed using 4/0 PDS^® or a similar suture. It is facilitated by placing two stay sutures at the membrano-cartilagenous junctions to orientate the airway.

A continuous suture is used for the membranous trachea, followed by interrupted sutures to the cartilaginous trachea, which reduces the risk of stenosis from over-tight suturing.

Once the anastomosis is complete, it is important to check for an air leak. If necessary, the anastomosis can be reinforced with a local pedicled flap, such as an intercostal flap.

To avoid over-distraction of the anastomosis postoperatively, a loose suture can be placed between the chin and skin over the manubrium, to prevent extension of the neck, often known as a ‘Grillo stitch’. While effective, it can be uncomfortable for the patient.

17

Describe the different types of thoracotomy commonly performed

Posterolateral thoracotomy – which involves a curved incision through latissimus dorsi and serratus anterior.

Anterolateral thoracotomy – which involves a transverse incision anterior to latissimus dorsi.

Muscle-sparing thoracotomy – where the incision preserves both serratus anterior and latissimus dorsi.

These thoracotomies can be rib-sparing, but division or removal of a rib is occasionally required to increase exposure.

18

What are the principles of a posterolateral thoracotomy (Figure 13)?

The patient is placed in a lateral decubitus position, with the table flexed at the midpoint of the thorax to spread the ribs.

A ‘bean-bag’ or padded braces and straps are used to secure the patient on their side.

The skin is prepped from the spine to beyond the nipple, and from the axilla to upper abdomen.

The inferior angle of the scapula is marked (Figure 13A) and a curved incision is made in the line of the 6th rib:

a)

starting 3cm anterior to the spinous processes of the spine;

b)

passing 2cm below the angle of the scapula;

c)

ending beyond the anterior border of latissimus dorsi.

The subcutaneous tissues are separated, exposing latissimus dorsi, which is then divided using electrocautery (Figure 13B).

A second layer of areolar tissue, which fuses anteriorly with serratus anterior, is divided (Figure 13C).

Serratus anterior can then either be retracted anteriorly (serratus-sparing thoracotomy) or divided.

The scapula is retracted superiorly (Figure 13D) to count the exposed ribs by palpation, starting from the 1st rib, which is relatively flat.

For lung resections, the 5th intercostal space is usually entered.

The ipsilateral lung is deflated and an incision is made along the superior border of the rib, using electrocautery or a periosteal elevator, from erector spinae to the margin of serratus anterior.

The parietal pleura is then opened and the lung is allowed to drop away.

The pleural space is swept with a finger to check for adhesions, before placing a Finochietto retractor, which is spread cautiously to avoid rib fractures.

Mobilisation of the intercostal neurovascular bundle from the superior rib (thus avoiding direct pressure on the nerve by the rib retractor), division of the costotransverse ligament and muscle-sparing approaches are variations on the standard posterolateral thoracotomy.

19

What are the principles of thoracic stapling (Figure 14)?

Although there are a large number of stapling devices available, they can broadly be divided into closed/anvil staplers or open-jaw devices.

Closed or anvil staplers generally have a bar or pin to prevent extrusion of tissue from between the jaws. The bulk of the stapler head means that they are mostly used in open surgery. The Covidien TA™ and Ethicon TX ranges are used for closing vessels and bronchi.

Open-jaw devices (including the Covidien Endo GIA^™ series and the Ethicon Echelon Endopath^™ series) can be used for dividing lung parenchyma, bronchi or blood vessels, and are the mainstay of minimal access thoracic surgery. In the case of the bronchus and blood vessels, it is important to cleanly dissect out the structure to be stapled from surrounding lymph nodes and tissue.

The open jaw staples are available in a variety of lengths. It is important to choose the correct length staple to make sure that the structure is within the staple jaws with a clear margin (5-10mm) before firing, as there is some extrusion of tissue out of the stapler jaws as it fires.

These staplers seal both sides of the divided structure before cutting, meaning that back bleeding from the distal vessels or contamination from bronchial secretions is controlled.

A variety of staple cartridges are manufactured to allow for different tissue thickness, with the Ethicon Endopath^® range colour-coded based on staple length (Table 1). The Covidien Tri-Staple™ range, however, uses three staple rows on each side of the blade, each of a different staple height, in order to reduce stress on the outermost staple line and to improve tissue perfusion.

As stapler design has evolved, newer technology has been introduced, including:

a)

roticulating staplers (Figure 14) – which allow rotation of the stapler head on the body of the stapler. This makes orientation to structures easier and is particularly useful in thoracoscopic surgery;

b)

powered staplers (such as the powered Ethicon Echelon™ stapler and Covidien iDrive™, Figure 15) – which can make the firing of the staple smoother (important when stapling delicate vascular structures) but is at the expense of an increased handle bulk;

c)

curved tip staples (Figure 16) – which may be easier to manoeuvre around structures to be stapled.

In general, choosing the right staple is important, as an undersized staple is likely to tear or misfire, whilst an oversized staple may not be haemostatic or airtight.