Advanced techniques in local anaesthetic thoracoscopy

Chapter 21


Advanced techniques in local anaesthetic thoracoscopy


Rahul Bhatnagar1,2, Rachel Jones3 and Nick Maskell1,2


1Academic Respiratory Unit, University of Bristol, Southmead Hospital, Bristol, UK. 2North Bristol Lung Centre, Southmead Hospital, Bristol, UK. 3Intensive Care Unit, Musgrove Park Hospital, Taunton, UK.


Correspondence: Rahul Bhatnagar, Academic Respiratory Unit, University of Bristol, Learning and Research Building, Southmead Hospital, Southmead Road, Bristol, BS10 5NB, UK. E-mail: Rahul.Bhatnagar@Bristol.ac.uk



Interventional pulmonologists are increasingly using local anaesthetic thoracoscopy to diagnose and treat pleural diseases. Within this technique, there are a range of applications that may be considered more advanced and are thus usually performed by those practitioners with additional experience or a research interest. This chapter discusses the evidence and practicalities behind advanced thoracoscopic procedures, including cryoprobe biopsy, the use of diathermy, talc pleurodesis, and the management of pneumothorax and pleural infection.


Cite as: Bhatnagar R, Jones R, Maskell N. Advanced techniques in local anaesthetic thoracoscopy. In: Herth FJF, Shah PL, Gompelmann D, eds. Interventional Pulmonology (ERS Monograph). Sheffield, European Respiratory Society, 2017; pp. 307–324 [doi.org/10.1183/2312508X.10004317].


Endoscopic examination of the thoracic cavity was once the sole domain of those with formal surgical training. The last few decades, however, have seen the increasingly widespread introduction of local anaesthetic thoracoscopy (LAT), typically undertaken by pulmonologists with an interest in intervention or pleural disease. Interchangeably referred to as medical thoracoscopy or medical pleuroscopy, LAT is becoming available to an ever-growing proportion of the world’s medical professionals and patients [1, 2], and now forms a vital part of many services’ pleural effusion pathways. The reasons for LAT becoming more popular are numerous and vary from region to region, but are likely to include lower costs and reduced waiting times (when compared with thoracic surgery), and less strict exclusion criteria due to general anaesthetic not being required. In general, however, centres with ready access to thoracic surgical colleagues are perhaps less likely to need to develop LAT services.


As skills, experience and confidence have progressed in some of those centres that have adopted LAT, the line between traditionally “surgical” procedures and those undertaken by physicians has become blurred. Similarly, a spectrum within LAT appears to be emerging, with a greater distinction between “basic” LAT, performed by the majority, and “advanced” LAT, which is usually confined to tertiary or research-focused centres.


The British Thoracic Society (BTS) guidelines divide thoracoscopy practitioners into levels I, II and III, with level III referring to VATS techniques beyond the remit of most physicians and the scope of this chapter (table 1) [3]. The definitions of “basic” and “advanced” LAT are not universal, however, and may vary according to the procedure(s) performed and/or the indication for which LAT is being attempted. For those who perform LAT infrequently, anything beyond routine (stripping) biopsies in a patient with a moderate to large effusion is likely to be considered “advanced”, whereas those with relatively more experience may develop competence to attempt more invasive or less straightforward procedures.



Table 1. Summary of the British Thoracic Society thoracoscopy expertise levels I, II and III
































Level I (basic)


Level II (advanced)


Level III (thoracic surgeon)


Sedation


Light, physician controlled


Deep, either physician or anaesthetist controlled (general anaesthetic in select centres)


General anaesthetic


Effusion


Intervention in large, simple effusions


Intervention in small effusions/no effusion if induced pneumothorax possible or those with early fluid complexity


Any


Biopsy


Basic pleural stripping or nodule sampling


Cryobiopsy (parietal), diathermy (parietal, visceral or pinch lung biopsy)


Any


Intervention


Simple adhesiolysis, talc poudrage for effusion


Mature adhesiolysis using diathermy (e.g. pleural infection), talc poudrage for pneumothorax, nerve chain lysis in very select centres


Any, including lung resection


Information from [3].


For the purposes of this chapter, we have chosen to largely define advanced LAT in line with the BTS level II standard, relating to procedures carried out by physicians on patients under sedation. We also discuss thoracoscopic poudrage, what we consider to be rarer or more technically challenging biopsy techniques and those interventions that remain confined to the experimental or research arenas. Such techniques, save perhaps talc poudrage, are not required by the majority of LAT practitioners and are usually only adopted following many years of practice at a basic level. Many of these diagnostic and therapeutic procedures are discussed in other chapters throughout this Monograph [4].


Finally, in general, the evidence base in this area is lacking, as most research relating to LAT comes in the form of expert opinion, case series or retrospective analyses of practice. That being said, literature quoted in this chapter emanates from across Europe (where LAT was first developed) and the rest of the world, and as such we believe what follows will be of value to a wide audience.


Pre-procedure


Hospital environment


A major appeal of LAT is that it may be performed safely in hospital environments outside of the operating theatre, such as an endoscopy suite. Indeed, data would suggest that the incidence of complication, major or otherwise, is extremely low and this is demonstrated in table 2 [3, 5]. However, as a practitioner begins to perform increasingly invasive, and thus theoretically riskier, thoracoscopic procedures, it becomes more important that these risks are appropriately mitigated. To accomplish this, several factors should be considered and first among these is the more general hospital environment. We would advocate ready emergency access to either onsite thoracic surgical cover or experienced interventional radiology (ideally both) to intervene in the event of significant vascular or visceral damage. To complement these, there should also be appropriate anaesthetic and intensive care support available.



Table 2. Local anaesthetic thoracoscopy complications and mortality reported in large retrospective series within the last 25 years









































































First author [ref.]


Year


Total patients N


Mortality %


Major complication rate n/N (%)#


MATURU [6]


2015


264


0.4


16/264 (6.1)


AGARWAL [7]


2014


128


0


2/128 (1.6)


GAO [8]


2014


215


0


0/215 (0)


METINTAS [9]


2013


355


0.3


50/355 (14.1)


METINTAS [10]


2010


124


0


3/124 (2.4)


MEDFORD [11]


2009


124


0.8


5/124 (4.0)


SAKURABA [12]


2006


138


0


0/138 (0)


HANSEN [13]


1998


146


0


3/146 (2.1)


MACHA [14]


1993


687


0


4/687 (0.6)


BOUTIN [15]


1993


188


0


4/188 (2.1)


#: major complications include pneumonia, empyema, extensive surgical emphysema, prolonged air leak, bleeding, venous thromboembolic events, cardiovascular insufficiency, respiratory failure and re-expansion pulmonary oedema. Reproduced and modified from [5] with permission.


The procedural environment must also be optimised. An appropriate number of support staff must be available, adequately trained and versed in the procedures being undertaken, as well as the potential risks and the protocols to be followed in the event of emergency. Although LAT can often be performed with a single operator, it may also be prudent to provide for additional medical support. However, whether this extends to include direct anaesthetic involvement is somewhat contentious.


Sedation and analgesia


LAT can typically be accomplished with relatively light intravenous sedation and analgesia, using benzodiazepine and opiate medications that are familiar to the pulmonologist (e.g. midazolam and fentanyl) [3]. With these drugs, it is common practice for the primary operator to oversee the patient’s conscious level alongside the intervention itself. In some centres, however, the role of monitoring this aspect of the procedure is delegated to an anaesthetist. Although such arrangements may liberate the operator to focus on more invasive procedures and have been used to excellent effect by surgeons [16], an attraction of LAT to many is the reduced resources required compared with VATS. Nonetheless, the use of certain anaesthetic agents, especially propofol, is attractive to pulmonologists due to an encouraging evidence base in bronchoscopy [17, 18] and their rapidity of onset and offset, with a feasibility study suggesting this may be a reasonable approach for LAT [19].


The question of whether physician-led propofol could replace standard sedation was addressed in a randomised trial of 90 patients in 2014. GRENDELMEIER et al. [20] concluded that, although no procedure had to be abandoned and no patients required treatment escalation, the use of propofol was associated with a significantly higher rate of hypoxaemia. This led GRENDELMEIER et al. [20] to conclude that this regimen should not be considered first line and triggered the early cessation of a similar study in South Africa [21]. This approach is still advocated by some, however, who argue that, with intensive, anaesthetist-led training for all involved in LAT (something that was not used in the GRENDELMEIER et al. [20] study), high standards and safety can be achieved routinely [19, 22].


Accessing the small pleural space


One of the primary differentiators between a basic and advanced LAT practitioner is the size of the effusion or pleural space that they might consider safe for intervention. Even with thoracic ultrasound guidance, a small collection may present a significantly higher risk of visceral or diaphragmatic damage compared with a moderate or large effusion.


Reducing the size of instrumentation may help to alleviate some of this risk. So-called “mini-thoracoscopy” (figure 1) uses instruments with diameters of up to 5–6 mm to try to achieve this, with diagnostic yield in one small series being comparable to that seen with larger devices [23]. Modern mini-thoracoscopes offer a wide range of interventional options and are seen by some authors as an ideal way to expand the reach of LAT [24].



ERM-0043-2017.01.tif

Figure 1. Example of a mini-thoracoscope designed for single port use (Richard Wolf, Knittlingen, Germany).


Perhaps the more usual method for approaching the small pleural space, however, is the induction of an artificial pneumothorax. This technique had a place in pulmonology for many decades [25], but became less familiar to most modern practitioners with the success of antituberculous medications. Due to the negative pressure within the pleural cavity, creating an open connection to the atmosphere will result in a pneumothorax. Doing so will cause the lung to “fall away” from the internal chest wall and thus create a space that can be dissected into at LAT. This effect is enhanced further by placing the patient in the typical lateral decubitus position. An artificial pneumothorax is usually induced in a controlled fashion by inserting a blunt, wide-bore needle into the small pleural effusion. Although this is often achieved with a Boutin trochar system, it may just as easily be performed using the Veress needle (with its spring-loaded safety device) more commonly used to induce a pneumoperitoneum prior to abdominal surgery (figure 2). Following insertion of the needle, the patient should be encouraged to take 15–20 slow deep breaths to facilitate lung collapse. Regardless of the device, direct ultrasound guidance should be considered for all such procedures.



ERM-0043-2017.02.tif

Figure 2. a) Boutin trochar needle. Reproduced with kind permission of Novatech (La Ciotat, France) ©Novatech S.A. France. b) Veress insufflator needle. Reproduced with kind permission of Genicon (Winter Park, FL, USA).


Some centres choose to attempt induction of a pneumothorax “on the table”, immediately prior to the procedure. While this runs the risk of having to abandon a LAT if the lung is excessively adhered, evidence would suggest that an assessment of pleural “sliding” on ultrasound can reliably predict those lungs that will collapse as intended [26]. This means that, even in patients with the smallest of pleural effusions, careful blunt dissection may be sufficient to allow LAT to take place (figure 3). An alternative approach is to induce a pneumothorax ∼2 h before a LAT and to confirm its size using a lateral decubitus chest radiograph. This approach minimises the likelihood of encountering a lung that has been unable to reduce in volume due to the presence of unseen, mature, parietovisceral adhesions. However, in the scenario of a “failed” LAT such as this, switching immediately to an ultrasound-guided cutting needle biopsy may be enough to achieve sufficient tissue in the large majority of cases, thus obviating the need for more invasive intervention [27].



ERM-0043-2017.03.tif

Figure 3. Ultrasound image of a small pleural effusion for which induced pneumothorax prior to thoracoscopy would be appropriate.


Induced pneumothorax has been shown to be safe when performed by expert centres. One group described 77 consecutive ultrasound-guided pneumothorax inductions, which comprised just over a third of the total number of LAT cases undertaken over a 3-year period. Encouragingly, no significant complications were reported [26].


Advanced diagnostic techniques


Cryoprobe biopsy


Obtaining sufficient tissue during pleural biopsy is of paramount importance. In cases of clear malignant infiltration, it is usually sufficient to sample a selection of nodules to obtain a definitive histological diagnosis. Certain diseases, however, tend to be more challenging to sample, especially if they cause diffuse parietal pleural thickening rather than nodular change. Among these may be malignant mesothelioma, which also often requires histological evidence of fat invasion to be definitively diagnosed [28]. Standard pleural biopsy techniques, which involve the indentation and subsequent progressive stripping of sections of tissue layers, may fail more readily in such cases due to difficulty in achieving adequate sampling depth, difficulty gaining purchase on a hardened smooth surface or the presence of crush artefacts degrading sample quality [29, 30].


Parietal pleural cryobiopsy has the potential to alleviate some or all of these issues but, despite being first described in 1989 (and its increasing importance in diagnosing ILD at bronchoscopy), it still remains a relatively infrequently used technique at thoracoscopy [31, 32]. The apparatus usually consists of a freezing unit connected to a flexible cryoprobe, which is passed down the channel of a thoracoscope with a dedicated working channel. Practically, this usually means either a rigid mini-thoracoscope or, more commonly, a semirigid thoracoscope. The tip of the cryoprobe is rapidly cooled for ∼5 s, which flash-freezes any adjacent tissue and causes it to stick to the tip of the probe. By then removing the scope and probe together, the biopsy sample is separated from the sampling area and can be prepared for analysis (figure 4). Cryobiopsy techniques are discussed in more detail elsewhere in this Monograph [34].



ERM-0043-2017.04.tif

Figure 4. Use of pleural cryobiopsy to diagnose mesothelioma. a) Candle wax parietal pleural abnormalities; b) cryoprobe biopsy of target area; c) size of pleural biopsies (left: cryoprobe; right: forceps). Reproduced and modified from [33] with permission.


Several authors have reported success using pleural cryobiopsy, often comparing the size and quality of biopsy samples to those taken using standard flexible forceps during the same procedure [29, 30, 33, 3537]. In general, these series reported significantly larger biopsy sizes and a dramatic reduction in crush artefacts [29, 30] when using the cryoprobe, with no apparent increase in the rate of procedural complications [29, 30, 3537]. In one case report, a patient with challenging sarcomatoid mesothelioma was able to be diagnosed using cryobiopsy after failure of the more conventional approach [33]. Only one series has compared rigid biopsies with both flexible and cryoprobe biopsies. The authors concluded that, although rigid sampling remains the gold standard for tissue volume and improving depth (being significantly better than either of the other approaches), cryoprobe biopsies are themselves significantly better than standard flexible biopsies [35].


Improving videoscopic appearance


The typical thoracoscopy, much like bronchoscopy or endoscopy, involves the use of “white” light, giving the operator a visual representation of the pleural landscape akin to using their own eyes in natural light. In some circumstances, however, differentiating between normal, inflammatory and malignant tissue areas can be extremely challenging using this method.


A number of attempts have been made to try and overcome this by altering the images sent back to the LAT operator. Broadly speaking, this involves adapting the wavelengths of light detected by the thoracoscopy camera system based on the behaviours of different types of tissue under varying conditions. The different techniques may be broken down into photosensitiser-enhanced fluorescence, autofluorescence and NBI. The first relies on both the prior administration of a fluorescing agent and a suitably stimulating light generator, the second on just the light generator, and the third on the use of specific light wavelengths that are known to be well absorbed by vascular structures. MYERS and LAM [38] provide a more detailed description of some of these specific techniques in the context of early lung cancer detection.


Following small animal studies, the first description of such an approach was published in 2004 [39] and was followed up in 2006 by a small series from the same centre [40]. NOPPEN et al. [40] asked 12 patients with primary spontaneous pneumothoraces (and 17 controls) to inhale a solution of 10% fluorescein prior to LAT. Under “blue” light, areas of subpleural photosensitiser accumulation were seen in areas that were not otherwise picked up with conventional white light, suggesting that there may be a role for improving targets for visceral intervention (figure 5). Some groups have used 5-aminolaevulinic acid as the photosensitiser, this time pre-administered orally, and concluded that there was a subjective improvement in being able to identify areas for pleural biopsy as areas of suspected malignancy were highlighted as bright red. The effect was particularly useful in cases of mesothelioma as up to 57% of patients could be upstaged due to the identification of additional lesions [41, 42].


Mar 8, 2018 | Posted by in RESPIRATORY | Comments Off on Advanced techniques in local anaesthetic thoracoscopy
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