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Background introduction
The celebrated American oto-rhino-laryngologist Chevalier Jackson[1] has been an important player in the field of bronchoscopy since the 1920s. His instrument, with a few modifications, became what is basically the rigid bronchoscope (RB) of today. By the 1950s, bronchoscopy became a well-established procedure, and every trainee thoracic surgeon had to be proficient in diagnostic and therapeutic bronchoscopy, the latter being confined to foreign body (FB) removal, clearing the tracheo-bronchial tree of secretions, cauterization of bleeding tumours and therapeutic bronchial lavage.
The flexible fibreoptic bronchoscope (FFB) was developed in the 1960s, the first instrument being designed by the Japanese, Shigeto Ikeda[2]. Its flexibility allowed examination of segmental bronchi. Until then this had only been possible with the use of straight and right-angled telescopes introduced through the rigid bronchoscope. The ease of FFB bronchoscopy under topical anaesthesia and sedation attracted respiratory physicians, and for thoracic surgeons, the flexible instrument became an important addition to bronchoscopic instrumentation for use independently or in conjunction with the rigid instrument. At present, for the thoracic surgeon, the two instruments are complementary to one another, and skills in both are necessary for the diagnosis of endobronchial lesions and for therapeutic endoscopic interventions.
Instrumentation and general principles of therapeutic bronchoscopy
Rigid bronchoscope (RB)
RB alone, or in conjunction with the FFB, remains the instrument of choice and sine qua non of many therapeutic bronchoscopies. Accessory devices include a range of forceps for grasping, provision of biopsy and/or punching/coring out tumours, dilators and diathermy probes. In addition, operative bronchoscopes have been designed for specific interventions such as lasertherapy[3,4]. Rigid bronchoscopy is performed under general anaesthetic during which ventilation is provided most effectively by hand-operated (Sander’s) injectors or jet ventilation. The author’s preference is the injector, since it allows effective control by the anaesthetist.
Flexible fibreoptic bronchoscope (FFB)
There are now a number of FFBs available with various accessory devices, such as biopsy forceps, needles for injection, aspirators and dilators.
FFB offers a recording system and monitor for live viewing and storing of bronchoscopic events. It can incorporate a fluorescence imaging system for auto-fluorescence bronchoscopy (AFB), which is several times more sensitive than white light in imaging pre- and early neoplastic endobronchial lesions.
FFB is essentially a diagnostic tool, which can be used under local/topical anaesthetic and sedation. Some models provide facilities for delivery devices for some of the therapeutic endoscopic methods. However, its use alone for interventional bronchoscopy, though publicized by some, can be uncomfortable for both patient and operator. Also, it can prove hazardous if there is bleeding which requires rapid clearance or control, and it can hinder a procedure when there are copious bronchial secretions which, in some patients, make the operation akin to an ‘underwater’ undertaking. This is because the suction channel is too narrow to be efficient for serious volume and high-viscosity secretions.
For many therapeutic bronchoscopies, the combined use of RB-FFB under general anaesthetic is the ideal method of practice. This allows comfort for patient and operator, efficient visualization of the lesion using white light and fluorescence bronchoscopy, precise targeting and application of the delivery device undisturbed by cough or bronchial secretion. It is important to note that such a method is not incompatible with treatment being undertaken as a day-case procedure.
Therapeutic bronchoscopic methods
This chapter will describe the most frequently used methods of therapeutic bronchoscopy, particularly those for which important experience is available to be relied upon. Nevertheless, mention is made of methods which are less universally employed. (Table 5.1) Available therapeutic bronchoscopic methods include
Bronchial cleansing and lavage
Retrieval of foreign bodies (FB)
Cryotherapy
Electrocautery
Argon plasma coagulation
Radiofrequency ablation
CO2 laser
Neodymium–yttrium aluminium garnet (Nd:YAG) radiation
Intraluminal radiotherapy/brachytherapy
Photodynamic therapy (PDT)
Stent
The basis for selecting a method for a given patient is governed by
The morphology of the lesion within the bronchial lumen
The histopathology of the lesion
The objective of therapy
The experience of the operator
| i | Mechanical | Cleaning of bronchial tree/bronchial lavage |
| Retrieval of FB | ||
| ii | Thermal | Cryotherapy |
| Electrocautery | ||
| Plasma argon coagulator | ||
| Radiofrequency | ||
| CO2 laser | ||
| Nd:YAG laser | ||
| iii | Biological | Brachytherapy |
| (cancer-specific methods) | PDT | |
| iv | Stents |
Mechanical methods
Bronchoscopic clearing of the airway
This is one of the simplest of procedures, commonly practiced by thoracic surgeons in patients with retention of secretions after pulmonary resection. When seriously tenacious secretions are present, the FFB is often inappropriate and ineffective. Passing a RB down the upper airway of a patient under topical anaesthetic is a simple and easy procedure to master. This is even easier when the patient is sitting up in bed.
Bronchoscopy and suction of copious secretions in patients with collapse (atelectasis) of the residual lobe or even the whole lung is attended by immediate expansion of the lung if sputum retention is recognized early enough before pneumonic consolidation sets in.
Bronchial lavage (synonym: whole lung lavage)
Classically, in this procedure, a large volume (several litres) of normal saline is introduced into the bronchial tree and aspirated. The procedure has been identified for treatment of pulmonary alveolar proteinosis[5,6]. A modification of the technique has also been used for other broncho-pulmonary conditions in which copious purulent secretions teeming with antibiotic-resistant bacteria or fungal organisms cause repeated pulmonary infection (e.g. cystic fibrosis and extensive bronchiectasis). In such cases, lavage, using saline or a suitable aqueous mild antiseptic solution, is instilled into the bronchial tree by repeated injection of 50 ml of solution at body temperature, followed by aspiration. The aim is to thoroughly clear the bronchial tree from debris or purulent and thick secretion.
Foreign-body (FB) retrieval
A variety of FBs have been removed from patients of all ages. The rigid bronchoscope remains the instrument of choice for the purpose, to be used under general anaesthesia. Occasionally, the fibreoptic instrument needs to be used if the FB is in a lobar or segmental bronchi, inaccessible to the rigid instrument.
In theory, the thoracic surgeon should be in a position to introduce a range of rigid scopes which match the size/age of the patient. In practice, however, the contemporary trainee surgeon is not exposed to such a range of patients and should at least be accustomed to adults of either sex, adolescents and teenagers.
Thermal methods
Cryotherapy
Cryotherapy is a treatment which deploys freezing to achieve necrosis of pathological tissues. The method is based on a rapid freeze of less than −40°C, within seconds, followed by a slow thawing, which leads to destruction of the targeted tissue[7].
The mechanism involves the formation of ice crystals both within the cell and in the extracellular compartment.
In addition, there are also vascular effects: vasoconstriction followed by vasodilatation and vascular thrombosis within 6–10 hours. This effect is induced via a probe delivering nitrous oxide (N2O) which is passed through the bronchoscope.
There are a variety of flexible and rigid cyroprobes to match the FFB or RB.
Indications: Cryotherapy has been used for
Locally advanced endobronchial tumours, either benign or malignant. In the latter the aim is palliation of symptoms such as dyspnoea or haemoptysis.
Superficial endobronchial malignant tumours in patients ineligible for surgical resection, where the treatment is undertaken with curative intent.
Cryotherapy can also be used in association with chemo/radiation[8].
Instrumentation/equipment: Bronchoscopic cryotherapy requires
Bronchoscope: it can be performed under topical anaesthesia using a flexible bronchoscope and flexible cryoprobe[8]. However, many practitioners prefer and advocate the use of general anaesthetic with rigid bronchoscope and a rigid cryoprobe[9].
Cryotherapy device: This has three components:
○ Cryoprobe: This is the delivery device which targets the tissue to be treated. The rigid probe has an added heating device that the flexible probe does not have.
○ Transfer line: Connects the cryoprobe to the cooling agent (gas cylinder) and the command counsel.
○ The cooling agents: Most often liquid nitrogen (LN2) or nitrous oxide (N20). The latter is most often used.
Following cryotherapy the patient needs to have repeat bronchoscopy 8–10 days later in order to
Evaluate the extent of tissue damage/destruction
Remove debris/slough
Undertake possible additional treatment cycles
Complications: Reactive oedema leading to respiratory complications, haemorrhage and pneumothorax. Overall, it has been reported in 7–10% of cases[10].
Electrocautery/electrodiathermy
This method uses an electric current to generate and deliver heat via a probe in order to coagulate or vaporize the tissue[11]. There are two types of probes: monopolar and bipolar. The later carries high voltage and needs to be used through the RB to achieve vaporization/cutting effect; the monopolar probe can be used through the FFB with a low voltage for hemostasis. The bipolar system can deliver a mixed cutting and coagulation current.
Elecrocautery has been used in patients with haemoptysis; a 70% success rate has been reported[12,13]. It has also been used to vaporize obstructive lesions of the airway. However, the procedure is time-consuming when there is a bulky obstructing tumour within the bronchus.
Argon plasma coagulation (APC)
APC uses high-frequency electric current delivered via ionized argon gas (plasma). The process involves emission of a jet of argon gas which is ionized by a high-voltage discharge (approximately 6 kV). High-frequency electric current is then conducted through the jet of gas resulting in thermal coagulation. There is no physical contact with the lesion, thus enhancing the safety of the procedure. The depth of coagulation is usually only a few millimetres.
Indications: The indication par excellence is coagulation at a distance where the electrodiathermy probe and catheter cannot reach[14]. The second line indication is disposal of superficial and obstructing endoluminal tumours[12,13]. However, for bulky lesions, coagulation needs to be used in conjunction with piecemeal removal. APC is particularly attractive to practitioners wanting to use FFB under topical anaesthetic and sedation.
Equipment: The basic APC system is composed of an argon gas source, a computer-controlled high-frequency electrosurgical generator and the endoscopic probe.
Results: Control of haemoptysis is achieved in over 97% of patients[14]. Recurrence is to be expected in cancer cases, and long-term complete response is rare. Also, the relief of endobronchial obstruction is less effective, requiring a long session and repeat treatment.
Complications: APC is relatively safe and complications are rare. Nevertheless, haemorrhage, perforation, fire and gas embolism have been reported even in some experienced centres.[15]
Radiofrequency ablation (RFA)
Radiofrequency ablation (RFA) is a treatment modality employing an electromagnetic wave with the same frequency band as an electric scalpel commonly used in surgery and a radiofrequency interchange with an electric current. It is a minimally invasive modality. The insertion of the radiofrequency electrode into a tumour generates heat with the effect of tissue heating which induces coagulative necrosis and cell death. The method has been used in hepatic tumours and also peripheral lung tumours under CT guidance[16]. The bronchoscopic use has not had thorough clinical evaluation.
Bronchoscopic laser
The term LASER is an acronym for light amplification by stimulated emission of radiation. In essence, lasers are specific wavelengths of light. However, the term is now more generally used in reference to devices which produce a laser light, which is
Monochromatic, denoting that the emitted light comprises a single wavelength output;
Coherent, defining a close phase relationship between all components of the emitted light;
Collimated, meaning that the radiation propagation is a narrowly confined beam with low divergence.
Different lasers can generate and emit light across a broad range of the electromagnetic spectrum, but it is only those within the ultraviolet, visible light and infrared spectral regions that have found clinical application.
Classification: Lasers may be classified in a number of ways:
According to wavelength
Based on their effect on tissue (e.g. thermal/non-thermal)
Depending on their ‘gain medium’, that is, the element which generates the laser light
Currently, thermal bronchoscopic laser therapy is performed exclusively with the use of neodimium–yttrium aluminium garnet (Nd:YAG), although CO2 laser is used by ear nose and throat surgeons for the upper airway.
The basic Nd:YAG laser machine comprises a generator emitting light of 1064 nm (infrared) accommodated within the control console. The emitted light is colourless and, therefore the emission is coupled with a helium-neon aiming beam emitting 630 nm red light. In this way, the Nd:YAG beam can be visibly directed via an appropriate delivery optical fibre. This needs to be coupled with a cooling system.
The mechanism of action is thermal coagulative necrosis and vaporization (ablation) of the tumour using high power at 30–50 watts and pulses of 10–20 seconds.
Indications[17–20]: Bronchoscopic laser is used for
Benign tumours of major airways, when complete cure can be expected.
Locally advanced primary endobronchial malignant tumours (i.e. central lung cancer).
In these, anatomical and functional integrity of the airway is rapidly restored. The method has been, and continues to be, the most important indication in malignant endoluminal obstructive lesions of the airway needing immediate/urgent relief.
Primary early central lung cancer. This indication has not received general acceptance since the advent of PDT.
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