Bronchoscopic argon plasma coagulation in the management of airway disease in adults

INTRODUCTION — Argon plasma coagulation (APC) is an electrosurgical, noncontact thermal ablation technique that uses argon gas that is ignited into a plasma which is used to cauterize and devitalize tissue (for debridement and debulking), and/or to achieve hemostasis, which, in turn, can be used to debride and debulk tissue and/or to achieve hemostasis. While its use was originally focused on achieving surgical hemostasis and debulking gastrointestinal tumors, APC has since been used during bronchoscopy for similar purposes.

In this topic review, the indications, contraindications, procedural technique, and complications of bronchoscopic APC for the management of airways disease are presented. Other bronchoscopic techniques used to manage airway obstruction and the use of APC in the management of gastrointestinal bleeding are described separately.

●(See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults".)

●(See "Endobronchial electrocautery".)

●(See "Endobronchial photodynamic therapy in the management of airway disease in adults".)

●(See "Airway stents".)

●(See "Flexible bronchoscopy balloon dilation for nonmalignant airway strictures (bronchoplasty)".)

●(See "Endobronchial brachytherapy".)

●(See "Bronchoscopic laser in the management of airway disease in adults".)

●(See "Bronchoscopic cryotechniques in adults".)

PRINCIPLES OF ARGON PLASMA COAGULATION — Contrary to a common misconception, APC is not a laser. Argon gas is expelled from a probe which then contacts a high-voltage electric current at the probe tip. When the argon gas contacts the electric current, it becomes ionized into a plasma and conducts a monopolar electric current that "grounds" itself to the nearest target lesion (picture 1) [1]. Thermal energy is delivered with a depth of penetration of roughly two to three mm. The heat produced denatures protein and evaporates intra- and extracellular water with the net effect of tissue destruction and coagulation.

Due to these features, APC is a useful modality for the treatment of almost all lesions within the airway, especially those that are highly vascular or bleeding. Although the shallow depth of penetration compared with laser means that it is not as efficient at debulking tissue, it can still be used successfully for this purpose. In contrast with laser, the plasma coagulates both linearly and tangentially; thus, when ionized gas travels linearly, it coagulates the lesion in direct view of the bronchoscope, but, as it travels to the point of nearest grounding, it can be applied laterally to treat lesions around folds or bends that are not clearly in view. (See "Bronchoscopic laser in the management of airway disease in adults", section on 'Principles of laser resection'.)

Argon gas is nonflammable and inexpensive to refill, making it one of the cheaper bronchoscopic ablative techniques available to interventional bronchoscopists.

INDICATIONS AND EFFICACY — In general, bronchoscopic APC is an immediate-acting therapy used to relieve/palliate symptomatic central airway obstruction (CAO; trachea and main stem bronchi) due to malignant or benign conditions. It is ideally suited to treating short, flat, intraluminal obstructing and/or bleeding lesions, as well as those at or around bifurcations in the airway (eg, proximal segments of upper or lower lobe airways), though can be used for almost all intrinsic obstructing airway lesions. It is not suitable for lesions causing CAO from extrinsic compression, for treating airway stenosis unrelated to an endobronchial lesion, or tracheobronchomalacia. The outcome is best if the airway lumen can be visualized beyond the obstruction and the distal lung is still functional; however, obstructions in lobar or segmental bronchi or large, extensive lesions where an airway is not easily identified may be more amenable to APC than laser or electrocautery. (See "Bronchoscopic laser in the management of airway disease in adults" and "Endobronchial electrocautery".)

The management of patients with CAO and choice of modality used to treat this population, including locally ablative bronchoscopic techniques, are discussed separately (table 1 and table 2). (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults".)

Central airway obstruction — Lesions associated with CAO that may be amenable to bronchoscopic APC can be either malignant or nonmalignant.

Malignant

Patient or tumor characteristics — Symptomatic CAO (eg, CAO with hemoptysis, dyspnea, cough, postobstruction pneumonia) from bronchogenic carcinoma is the most common indication for bronchoscopic APC (table 3) [2-5]. It is generally a palliative therapy used in patients for whom other first-line treatment modalities are not feasible, as well as in patients who require immediate relief from serious, life-threatening intraluminal obstruction and/or hemoptysis. Occasionally, it is used adjunctively before salvage chemotherapy, radiation, or resection. Ideal lesions suited to APC are those that are intraluminal, short (<4 cm), vascular, and/or superficial with a flat or polypoid shape (eg, papillomatosis (picture 2)), as well as those that are located around bifurcations of airways. Ideally, functional lung beyond the obstruction should be visually evident. Its effects are generally temporary such that it is usually combined with other therapies (eg, stenting, dilation, brachytherapy, or external beam irradiation); alternatively, it can be repeated for palliative purposes. (See "Endobronchial electrocautery" and "Airway stents" and "Flexible bronchoscopy balloon dilation for nonmalignant airway strictures (bronchoplasty)" and "Endobronchial brachytherapy" and "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults" and "Bronchoscopic cryotechniques in adults".)

Non-small cell lung cancer (NSCLC) is the most common malignancy treated with this modality since NSCLC is the most common cancer to affect the airway. However, case reports of successful management of other types of malignancy have been described, including endobronchial carcinoid (especially polypoid lesions) and metastatic tumors affecting the bronchus (eg, lung, breast, or colon) [6,7]. APC in conjunction with other techniques has been used to treat bronchial mucoepidermoid carcinoma in children [8].

Efficacy — Support for the use of APC in patients with malignant CAO is mostly derived from small, observational case series. As examples:

●In one prospective cohort study of 364 patients, 90 percent of whom had cancer and 50 percent of whom had obstruction, bronchoscopic APC (mostly rigid bronchoscopy; 482 interventions) resulted in airway patency in two-thirds of the treated population [2].

●In a retrospective cohort study of 60 patients, 90 percent of whom had bronchogenic carcinoma, treatment with bronchoscopic APC (mostly flexible bronchoscopy; 70 procedures) resulted in an overall decrease in the degree of airway obstruction from 76 to 18 percent [4]. All patients with obstructive lesions who survived also experienced symptom improvement (eg, dyspnea, hemoptysis, cough, postobstructive pneumonia).

●A similar study of 47 patients who underwent repeated APC (an average of more than three sessions per patient) reported successful outcome (obstruction and/or symptoms) in 92 percent of patients, which was maintained over a mean follow-up of 6.7 months [3].

Comparison with other techniques — Although there are no high-quality studies comparing the use of APC with other bronchoscopic ablative therapies, the use of APC when combined with mechanical debridement has been associated with higher rates of airway patency and symptom palliation (hemoptysis, dyspnea, or cough) [9,10]. A study comparing APC with mechanical tumor extraction to cryorecanalization suggested improved efficacy with APC [9]. Our experience supports a database report of therapeutic bronchoscopy procedures that suggested that APC has replaced laser resection as the most commonly used thermal ablation modality [10]. One retrospective review of bronchoscopic treatment of benign endobronchial tumors reported that there was no difference in efficacy between diode laser and APC, at times in combination with cryotherapy [11].

However, choosing which therapy to use in patients with airway tumors is dependent upon the tumor and patient characteristics, as well as local expertise, and should therefore be individualized for each patient. In addition, in practice, a combination of local therapies is used to optimize and maintain patency. As an example, initial tumor debulking with forceps, (ie, mechanical debridement) or removing surface eschar with cryoprobe can be utilized prior to APC (for further debulking). Among these modalities, only APC, electrocautery, and laser resection can destroy tissue rapidly and, therefore, have an immediate effect. APC may be more efficient than electrocautery or laser resection at achieving hemostasis but is less efficient at debulking tissue. The advantages and disadvantages of each bronchoscopic modality and choosing among the therapeutic options (both immediate-acting and maintenance therapies) in patients with CAO are discussed in detail separately (table 1 and table 2). (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults", section on 'Choosing among modalities' and "Endobronchial electrocautery" and "Airway stents" and "Flexible bronchoscopy balloon dilation for nonmalignant airway strictures (bronchoplasty)" and "Endobronchial brachytherapy" and "Bronchoscopic cryotechniques in adults".)

Nonmalignant — In patients with significant CAO from nonmalignant airway disease, bronchoscopic APC is generally a second-line therapy used for those who decline or are not candidates for first-line therapies such as curative surgical resection (table 3). Similar to patients with malignancy, nonmalignant lesions best suited to bronchoscopic APC resection are short (ie, <4 cm), flat, polypoid, intraluminal masses, particularly those associated with significant hemoptysis. Patients with extrinsic compression from nonmalignant extraluminal conditions (eg, large goiter, sarcoid-related lymphadenopathy) are not candidates for APC. (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults".)

Data to support treating this population with bronchoscopic APC are derived from isolated cases reports or case series that report success (ie, relief or airway obstruction and/or symptom palliation) with this modality [2,6,11-22]. Examples include:

●Nonmalignant strictures/obstruction due to granulation tissue from stents or anastomoses (eg, following lung transplant)

●Nonmalignant polyp or tumor removal (eg, benign metastasizing leiomyoma, subglottic hemangioma, lipoma, hamartoma, chondroma, papillomatosis, airway fibroepithelial polyposis)

●Central airway obstruction by various infections

●Fistula repair (rare indication as tissue destruction can enlarge the fistula)

●Dieulafoy disease (vascular lesions of the airway; rare indication)

●Lung abscess drainage (rare indication)

In a retrospective review of 10 patients with nonmalignant endobronchial tumors, all patients achieved tumor regression when bronchoscopic APC was used in combination with other locally ablative techniques, electrocautery, or cryotherapy [12]. Most were performed using moderate sedation and flexible bronchoscopy.

Controlling airway bleeding — Bronchoscopic APC has been reported as successfully achieving high rates of hemostasis in patients with significant hemoptysis due to visible endobronchial lesions. In most cases, it is a palliative therapy administered when other treatments have failed (eg, correcting coagulopathy). However, the role of APC in treating massive, life-threatening hemoptysis is probably limited. As examples:

●In one prospective cohort study of 364 patients (most with bronchogenic carcinoma), APC resulted in hemostasis in the one-third of the cohort that presented with hemoptysis [2].

●In a retrospective cohort study of 60 patients with bronchogenic carcinoma who underwent APC, all patients who presented with hemoptysis experienced a resolution of bleeding immediately after APC [4]. No patients had recurrent hemoptysis during the following three months.

●Successful treatment of recurrent hemoptysis resistant to other therapies (eg, bronchial artery embolization) has been reported in lung transplant patients with hemorrhagic polypoid lesions and patients with Dieulafoy disease [16,19].

The etiology and management of hemoptysis is discussed separately. (See "Evaluation of nonlife-threatening hemoptysis in adults" and "Etiology of hemoptysis in adults" and "Evaluation and management of life-threatening hemoptysis".)

Early airway lung cancer not amenable to surgery — Whether APC can cure microinvasive radiographically occult lung cancer (ROLC) in patients who are not eligible for surgical cure is not fully established. While no large, prospective trials have rigorously compared APC with other bronchoscopic modalities, case reports suggest that locally ablative therapies, including APC, have the potential to be effective as a treatment for early lung cancer that is limited to the airways [5,23].

In one retrospective study, endobronchial therapies were successfully used to treat patients with ROLC [5]. However, electrocautery was the most common modality used in this study, and APC was only used in two patients. This study is discussed in detail separately. (See "Endobronchial electrocautery", section on 'Malignant tumors'.)

CONTRAINDICATIONS

Patients with extrinsic compression — Because heat needs to be applied directly to the lesion for efficacy, patients with central airway obstruction (CAO) solely due to extrinsic compression or due to a cartilaginous disorder (eg, tracheobronchomalacia or stenosis) are not suitable for bronchoscopic APC. However, obstructive intraluminal components of extrinsic lesions may be subjected to APC, if necessary.

Patients requiring high oxygen supplementation — Since oxygen is combustible, patients requiring a fraction of inspired oxygen >0.4 are at risk of airway fire, and APC, as such, is not typically advised, unless necessary and it is assessed that the benefits outweigh the risk of fire. (See 'Complications' below.)

Other — Nonmetallic airway stents (usually silicone), the covering on metallic stents, and endotracheal (ET) tubes are at risk of melting or igniting. However, this risk may be lower than for bronchoscopic laser and electrocautery. Thus, some experts cautiously use APC to dissect out granulation tissue or recurrent tumor in-growth in such stents for palliative purposes. On the other hand, APC is not as precise as some laser modalities. Metallic stents generally do not ignite/melt. (See "Airway stents" and 'Complications' below.)

APC may be less effective in patients with extensive (>4 cm in length) lesions. However, the depth of beam penetration when compared with laser and electrocautery is more shallow, such that some experts use APC cautiously in this population when the benefits of airway patency are assessed to outweigh the risk of airway perforation. (See 'Complications' below and "Bronchoscopic laser in the management of airway disease in adults", section on 'Complications' and "Endobronchial electrocautery", section on 'Complications'.)

Bronchoscopic APC involves either flexible or rigid bronchoscopy. Thus, contraindications to bronchoscopy, general anesthesia, and/or moderate sedation are also considered contraindications to bronchoscopic APC. These are reviewed separately. (See "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications", section on 'General considerations and precautions' and "Flexible bronchoscopy in adults: Indications and contraindications", section on 'Contraindications' and "Overview of anesthesia", section on 'Risk assessment'.)

Patients with any implanted electrical device (eg, defibrillator, pacemaker) are potentially at risk of adverse outcomes from APC. In general, discussion with a subspecialty service (eg, cardiac electrophysiology) and/or the manufacturer of the device is suggested prior to performing APC in this population [24]. Because the types and characteristics of implantable electrical devices differ, the indication for the device for each patient varies, and the potential for a complication real and avoidable, we feel it is best to discuss the case with healthcare provider managing this aspect of the patient's care and perhaps with the manufacturer if the provider deems it best, well before starting the case. This should ensure handling the device properly during and after the case and having any needed equipment on hand.    

EQUIPMENT AND PROCEDURE — Bronchoscopic APC should only be performed by bronchoscopists experienced in performing the procedure. It requires a bronchoscope (flexible or rigid), an APC probe, an electrical generator, an argon gas source, and a grounding pad that is placed on the patient's lower back or flank.

Equipment settings — Prior to the procedure, the equipment should be checked and its settings confirmed. Initial settings vary depending upon the operator and the target lesion. We suggest using the following:

●An applied power of 15 to 25 watts

●An argon flow rate as low as possible (ie, 0.2 to 0.4 L/min)

●An application time of one to two seconds

Adjusting the power setting and the application time affects how much tissue is destroyed. The higher the power and the longer the time, the more the tissue gets destroyed but, in general, with less control of depth of penetration. Also, higher power generates eschar/char that can obstruct the gas exit from the probe and thus limits the APC effect by blocking access to fresh tissue. Likewise, the eschar increases tissue impedance and ‘self-limits’ the depth of APC penetrations. Higher gas flow rates tend to produce a "longer" flame, which, in theory, can cover more tissue. However, at airway bifurcations or with a large endobronchial tumor that prevents seeing the airway beyond the lesion, this longer flame will "bend" around the surface, resulting in treating tissue that is not visible, thereby increasing the risk of perforation. In addition, although higher flow rates tend to clear the field of debris and blood better than lower rates, they may carry a higher risk of gas embolism. General settings to which the operator may advance are:

●Applied power – Up to 80 watts

●Argon flow rate – As low as possible (start with 0.2 L/min)

●Application time – Up to three seconds but can apply as long as desired (eg, five seconds)

Procedure — Bronchoscopic APC can be performed using a rigid or flexible bronchoscope, the latter being more common. For those suitable for flexible bronchoscopy (eg, patients with a stable airway and mild obstruction), the procedure can be performed under moderate sedation, while sicker patients, particularly those with an unstable airway, may be more suitable for rigid bronchoscopy, which is performed under general anesthesia. Some experts prefer to perform this procedure using a secure airway since it involves frequent passes of the bronchoscope for debulking and removing devitalized tissue. Once the patient is sufficiently sedated or anesthetized, bronchoscopy is performed, and the target lesion is visually identified. (See "Flexible bronchoscopy in adults: Overview" and "Flexible bronchoscopy in adults: Indications and contraindications" and "Rigid bronchoscopy: Instrumentation" and "Rigid bronchoscopy: Intubation techniques" and "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications".)

A flexible probe, which can be 1.5 up to 3.2 mm in diameter and 150 up to 330 cm in length, is then passed through the instrument channel of the bronchoscope or through the open barrel of a rigid bronchoscope and advanced until the location of its tip meets the following criteria (picture 3 and picture 1). There may be little difference in effect between the different diameter probes; however, the smaller probes allow their use with bronchoscopes with smaller diameter working channels. Additionally, using a smaller diameter probe with a larger working channel allows suctioning of smoke and debris around the probe, allowing for visualization of the field.  

●The probe tip should be several centimeters beyond the bronchoscope's tip to ensure that the bronchoscope will not be burned. Based on personal experience, we feel >2 cm is satisfactory.

●The probe tip should be several centimeters beyond the endotracheal (ET) tube or a covered metal or nonmetallic stent before firing to prevent damage or fire.

●The probe tip should be within 1 to 3 mm of the target lesion, in our experience, but preferably not in contact with the lesion. The electric current will not be conducted if the probe is too far away from the target lesion (ie, the electrical circuit will be open). In contrast, when the probe is in contact with tissue when fired, char often develops quickly on the probe tip, which blocks gas exit and current generation, thereby limiting APC effectiveness.

To debulk an obstructing lesion, the surface eschar is removed (eg, with forceps or a cryotherapy probe), and, then, APC is applied systematically to the underlying fresh tissue in one- to three-second bursts until the obstructing lesion is debulked sufficiently. The bronchoscopist starts at the initial settings and then incrementally increases the power (up to 80 watts) and time (up to three seconds, occasionally longer), according to the observed effect (see 'Equipment settings' above). The depth and volume of tissue impacted depend upon the applied power and the application time and perhaps, to a lesser degree, the gas flow rate. Thus, small, shallow lesions typically require less power and application time, while larger and deeper lesions require greater amounts of power and time. During the procedure, fragments of tissue should be aggressively removed manually, using a forceps, suction, or cryotherapy, so that fresh tumor can be ablated.

To achieve hemostasis, firing APC in short bursts (a few seconds) while moving the probe back and forth, "painting the airway," is often effective.

The probe should not be fired outside the airway to avoid shocking or burning staff, the patient, or the operator.

In our experience, the procedure should take no longer than one hour to achieve the target goal (eg, decrease obstruction, achieve hemostasis).

One commercially available device is a probe which combines APC and an electrocautery snare (picture 4) (see "Endobronchial electrocautery"). This allows the operator to switch conveniently between modalities as deemed appropriate. Several lengths are available (eg, 160 cm and 230 cm). The probe diameter is 2.5 mm, so a bronchoscope with a working channel large enough is needed. The settings for each modality can be adjusted independently. A power generator that accommodates both modalities is also necessary.

COMPLICATIONS — Specific complications of bronchoscopic APC are infrequent (typically less than 1 percent of procedures) but range from 0.5 to 4 percent, the most common of which are airway fire and airway perforation [2,4,25-28].

Types

●Bronchoscopy or sedation related – Many of the complications associated with bronchoscopic APC are related to the bronchoscopy and/or the sedation. These complications are discussed separately. (See "Rigid bronchoscopy: Intubation techniques", section on 'Complications' and "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications", section on 'Anticipating and mitigating Complications' and "Flexible bronchoscopy in adults: Overview" and "Flexible bronchoscopy in adults: Preparation, procedural technique, and complications", section on 'Complications' and "Overview of anesthesia", section on 'Risk assessment'.)

●APC related – Common complications of bronchoscopic APC that are shared with many ablative techniques (laser, electrocautery) include [2,4,25-28]:

•Airway fire/burns

•Airway perforation (resulting in pneumomediastinum, subcutaneous emphysema, pneumothorax, and fistula formation)

Less common complications include gas embolism and melting of stents or endobronchial tubes. Severe hemorrhage, electrical shock, burning of equipment, and death are rare.

Based upon the principles of other thermally-ablative bronchoscopic procedures (eg, laser electrocautery), airway fires can theoretically be minimized by avoiding high-flow oxygen (ie, avoiding fraction of inspired oxygen >0.4) during APC firing, limiting the applied power (less than 80 watts), and reducing the application time (less than three seconds). In addition, keeping the probe tip several centimeters away from any combustible material, such as an endotracheal (ET) tube, a nonmetallic stent, or a covered metallic stent, may minimize this risk (metal stents rarely ignite/melt); the exact distance that is safe is undetermined, and the recommendation is based on experience. Fire-safety procedures and management of airway burns are discussed separately. (See "Fire safety in the operating room" and "Inhalation injury from heat, smoke, or chemical irritants".)

Airway perforation is probably less common than with bronchoscopic laser because of the limited depth of penetration of APC. We have not encountered an APC-generated perforation. Perforation-related pneumothorax or pneumomediastinum should be managed accordingly, the details of which are discussed separately. (See "Complications of the endotracheal tube following initial placement: Prevention and management in adult intensive care unit patients", section on 'Tracheoesophageal fistula' and "Treatment of secondary spontaneous pneumothorax in adults".)

Most cases of hemorrhage can be treated locally due to the coagulant effect of APC itself. When brisk bleeding complicates the procedure, increasing the argon flow rate may blow blood away from the source, thereby providing better visualization of the culprit lesion. As with the other ablative techniques, perforating a large vessel can occur, with a serious adverse outcome. Care in selecting the target, the APC settings, and in applying the technique should minimize this risk. Should uncontrollable hemorrhage occur, intubation is necessary (if not already performed) so that other measures can be taken to achieve hemostasis, the details of which are discussed separately. (See "Evaluation and management of life-threatening hemoptysis".)

Gas may enter through the bronchial veins (bronchial lesions) to result in left heart gas embolism or through systemic veins (tracheal lesions) to result in right heart gas embolism [25,26]. Although the rate of argon flow was not considered high in reported cases, we prefer to maintain flow at less than 2 L/min to lessen the chance of gas embolism. Patients with gas embolism may present with sudden-onset cardiovascular collapse or neurologic changes suggestive of stroke. The procedure should be stopped immediately should embolism be suspected. The manifestations and treatment of patients with suspected embolism are presented separately. (See "Air embolism".)

One study has reported that the risk of igniting or melting nonmetallic stents (such as silicone) or covered metallic stents may be limited by keeping the power at 40 watts or less, the fraction of inspired oxygen at 0.4 or lower, and the argon flow rate at less than 0.8 L/min [28].

In our experience, keeping the probe tip several centimeters away from the bronchoscope tip and the ET tube most likely prevents the bronchoscope and ET tube from being burned. In addition, placing a grounding pad on the patient and keeping the probe tip away from conducting material decreases the chance of electrical shock to the patient.

Bacteremia was shown not to be an issue in one study [27].

Device malfunction from an implanted electrical device (eg, defibrillator) is a potential adverse outcome that has not been reported or encountered by our group.

Frequency — Rates of complications vary from series to series and depend upon operator experience, as well as individual tumor and patient characteristics. In one retrospective case series of 364 patients that underwent 482 interventions, the complication rate was reported as 3.7 percent [2]. In contrast, another series of 60 patients who underwent 70 procedures reported no complications directly related to the procedure and one death due to sepsis not related to the procedure [4].

POSTOPERATIVE CARE — Bronchoscopic APC does not require any particular, immediate follow-up care in the absence of complications, other than that required routinely for bronchoscopy. Patients usually can return home the same day when performed as an outpatient procedure. The follow-up of patients who undergo bronchoscopy, as well as patients who undergo treatment for central airway obstruction (CAO), is discussed separately. (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults", section on 'Follow-up' and "Flexible bronchoscopy in adults: Overview" and "Flexible bronchoscopy in adults: Preparation, procedural technique, and complications", section on 'Postprocedure monitoring'.)

SUMMARY AND RECOMMENDATIONS

●Principles – Bronchoscopic argon plasma coagulation (APC) is an electrosurgical, noncontact, thermal ablation technique that uses argon gas to generate heat, which, in turn, can be used to debride and debulk airway tissue and/or to achieve hemostasis. It should only be performed by bronchoscopists experienced in performing the procedure. (See 'Introduction' above and 'Principles of argon plasma coagulation' above.)

●Indications – Bronchoscopic APC is an immediate-acting therapy used to relieve/palliate symptomatic central airway obstruction (CAO) due to malignant or nonmalignant conditions. (See 'Indications and efficacy' above.)

•It is ideally suited to treating short, intraluminal obstructing and/or bleeding lesions, as well as those at or around bifurcations in the airway. (See 'Central airway obstruction' above.)

•Bronchogenic carcinoma, particularly non-small cell lung carcinoma (NSCLC), is the most common indication for bronchoscopic APC (table 3). (See 'Malignant' above.)

Other indications include the treatment of benign conditions associated with CAO (eg, polyp removal, debridement of granulation tissue around endobronchial stents), airway bleeding, and microinvasive radiographically occult lung cancer (ROLC). (See 'Nonmalignant' above and 'Controlling airway bleeding' above.)

●Contraindications – Bronchoscopic APC is not suitable for treating lesions causing CAO from extrinsic compression or stenosis unrelated to endobronchial tumor or tracheobronchomalacia. In addition, patients on high-flow oxygen (fraction of inspired oxygen >0.4) are not good candidates for bronchoscopic APC. While patients with nonmetallic or covered metallic airway stents or patients with extensive endobronchial lesions are also not ideal candidates, some experts perform APC in select patients in these groups when the benefits are assessed by the bronchoscopist to outweigh the risks. (See 'Contraindications' above.)

●Equipment and procedure – APC can be delivered using a flexible or rigid bronchoscope, the former being more common. Once the target lesion is bronchoscopically identified, a flexible APC probe is passed through the bronchoscope and advanced until the probe tip is several centimeters beyond the bronchoscope's tip and within 1 to 3 mm, but preferably not contacting, the target lesion. The argon gas then conducts an electrical current to the target lesion, which causes tissue destruction and hemostasis. (See 'Equipment and procedure' above.)

●Complications – Complications of bronchoscopic APC are infrequent (typically less than 1 percent of procedures) but range from 0.5 to 4 percent. They can be related to the bronchoscopy, sedation, or anesthesia or to the APC itself. The most common APC-related complications are airway fire, gas embolism, and airway perforation. Additional complications include melting of nonmetallic stents or endobronchial tubes, severe hemorrhage, electrical shock, burning of equipment, and death. (See 'Complications' above.)

●Postoperative care – Bronchoscopic APC does not require any particular immediate follow-up care in the absence of complications, other than that required routinely for bronchoscopy. (See 'Postoperative care' above.)