Chapter 16
Ultrasound-guided procedures
John P. Corcoran1,2, Mark Hew3, Fabien Maldonado4 and Coenraad F.N. Koegelenberg5,6
1Interventional Pulmonology Service, Dept of Respiratory Medicine, Plymouth Hospitals NHS Trust, Plymouth, UK. 2University of Oxford Respiratory Trials Unit, Churchill Hospital, Oxford, UK. 3Dept of Respiratory Medicine, The Alfred Hospital, Melbourne, Australia. 4Vanderbilt University Medical Center, Tennessee, Nashville, TN, USA. 5Division of Pulmonology, Dept of Medicine, Stellenbosch University, Cape Town, South Africa. 6Tygerberg Academic Hospital, Cape Town, South Africa.
Correspondence: John P. Corcoran, Dept of Respiratory Medicine, Derriford Hospital, Plymouth, PL6 8DH, UK. E-mail: jpcorcoran@doctors.org.uk
It is in the field of interventional pulmonology and as an adjunct to pleural procedures that TUS has gained its greatest foothold over the past decade, and where the evidence base for its continued use is undoubtedly strongest. There are many advantages to using TUS as a guide for invasive procedures, including a reduction in the risk of iatrogenic complications, increased diagnostic yield, patient and clinician satisfaction, cost savings and the avoidance of ionising radiation. This chapter will provide the reader with an overview of the published data underpinning current established practice in this field, alongside expert opinion from across the world on less commonly used techniques and how future research may potentially have an impact on clinical care and the way we work in the longer term.
Cite as: Corcoran JP, Hew M, Maldonado F, et al. Ultrasound-guided procedures. In: Laursen CB, Rahman NM, Volpicelli G, eds. Thoracic Ultrasound (ERS Monograph). Sheffield, European Respiratory Society, 2018; pp. 226–243 [https://doi.org/10.1183/2312508X.10007317].
As the technology has become more portable and reliable over the past two decades, TUS has become an indispensable tool for any physician managing patients with respiratory disease. Nowhere is this more evident than in the field of interventional pulmonology and pleural procedures, with post-graduate training documents increasingly focused on competency in this area of clinical practice [1–5]. The increasing familiarity of physicians with TUS means the range of pleural interventions being offered to patients has grown rapidly in recent years [6, 7], and has allowed physicians to take control of a diagnostic and therapeutic pathway that might previously have required the support of a radiologist or thoracic surgeon [8]. As a result, procedures are now being performed in a variety of settings around the hospital with increasing frequency, and on both an in- and outpatient basis.
It could be argued that long-recognised concerns around patient safety in the context of pleural intervention have been the single greatest driving force behind the widespread uptake of TUS by physicians [9, 10]. At this point in time, the evidence that the appropriate use of TUS reduces the risk of iatrogenic complications from pleural procedures in comparison with unguided (blind) intervention is so overwhelming that the authors would regard a failure to carry out a TUS examination prior to any intervention for suspected pleural fluid as being indefensible, except in the most exceptional circumstances (e.g. when operating in a resource-poor country or remote environment) [11–15]. A reduction in iatrogenic complications has obvious benefits for patients, but in turn reduces the burden and costs that might otherwise also be incurred for healthcare providers through increased length of stay and additional remedial interventions [13, 15].
The use of TUS as a diagnostic tool for a variety of lung parenchymal and pleural pathologies has been discussed at length in earlier chapters in this Monograph. The primary goal of this chapter is to look at how the use of TUS can, when appropriate, facilitate and enhance a diagnostic and/or therapeutic procedure in the context of different respiratory conditions. The chapter will also consider some of the technical aspects of performing an individual procedure and will, where necessary, direct readers to other resources; it does not aim to provide a step-by-step guide on how a particular intervention might or should be performed. In taking this approach, this chapter hopes to provide the reader with an understanding of key concepts relating to the use of TUS for procedural work including: 1) the practicalities of using TUS in a procedural setting (e.g. optimising patient positioning and safety during procedures, and technical considerations including probe choice, orientation and US modality), 2) the indications for and published data supporting the use of TUS during basic interventions (e.g. thoracocentesis, tube thoracostomy) for pleural fluid, 3) the indications for and published data supporting the use of TUS guidance during more advanced interventions (e.g. pleural, lung parenchymal and other related biopsies, and medical thoracoscopy), 4) the role of TUS as a predictor of clinical outcomes before and after pleural intervention and 5) the potential implications for training standards in TUS as an adjunct to procedural work.
Pre-procedural considerations
The importance of adequate preparation prior to any intervention must not be underestimated. Careful consideration should be given in turn to the working environment, patient factors, available equipment and supporting staff. Since the majority of procedures are likely to be delivered on a planned basis (i.e. outpatient or semi-elective inpatient), the operator should have sufficient time to be prepared for all eventualities. This experience can then be translated and adapted, where necessary, to suit the emergent setting; even in this less controlled environment, there are ways of mitigating risk through, for example, the use of algorithms and pre-prepared bespoke procedural kits that maintain safety and efficiency of working practices.
Patient factors
The decision to undertake any medical intervention involves balancing the risk of complications against the indications for and benefits of the procedure. As a minimum, this requires the operator to exercise due diligence with respect to those factors that might complicate or increase the risk of any given procedure. These will include, for example, clotting studies and/or use of anticoagulation [16], patient comorbidities including cognitive function and body habitus, and acuity of illness. Unless a procedure is being undertaken in the context of a life-threatening emergency, written informed consent should be obtained as standard, with appropriate time provided to discuss any potential complications associated with the intervention (table 1). The advance provision to the patient of an information leaflet outlining the benefits and risks of the procedure can simplify this process.
Table 1. Common and important complications associated with thoracic interventions that should be discussed with the patient when obtaining informed consent
Procedure | Complications | |
|---|---|---|
All transthoracic interventions | Failure to make a diagnosis or provide symptomatic relief (where applicable), pain, bleeding, superficial soft tissue infection, pleural infection, damage to the chest wall structures and/or underlying viscera including lung, difficulty breathing and/or re-expansion pulmonary oedema (where large-volume drainage of fluid or air is expected to occur) | |
Procedure-specific complications in addition to the above | ||
Tube thoracostomy (chest-drain insertion) | Tube malposition, s.c. emphysema | |
Indwelling pleural catheter insertion | Tube malposition, s.c. emphysema, development of chest pain requiring drain removal, infection of s.c. drain tunnel, unintentional dislodgement of tube, blockage of tube, development of septated fluid with subsequent failure of drainage, metastatic seeding at drain site and/or along s.c. tunnel (if malignant pleural disease), tube fracture on or prior to removal | |
Image-guided transthoracic biopsy (pleural, lung) | Early (immediate) or delayed (up to 24 h) pneumothorax following biopsy | |
Medical thoracoscopy | Tube malposition, s.c. emphysema, cardiac arrhythmia in association with procedure and/or use of analgosedation, failure of pleurodesis (if talc poudrage performed), adult respiratory distress syndrome and severe hypoxaemia (if talc poudrage performed), death | |
Information from [17–24]. | ||
Taking time to optimise the patient’s position for both TUS examination and the subsequent planned intervention is critical, yet often underappreciated. This should be considered in advance whenever possible, and guided by the area(s) of greatest interest as determined from prior imaging (e.g. chest radiograph, CT). The posterior chest is most easily examined with the patient in a seated upright position, resting their arms on a table or other support placed in front of them. It is worth highlighting that if a patient is leant too far forwards onto their support, it may be difficult to keep a needle perpendicular to the chest wall and create a situation whereby the path of the needle heads superiorly in the rib space towards the neurovascular bundle. The lateral and anterior chest can be examined with the patient either semi-supine or in lateral decubitus, while the superior sulcus, supraclavicular fossa and neck can be inspected in a seated, semi-supine or supine position. Regardless of the position thought to be optimal from the operator’s perspective, the patient must be able to tolerate remaining in that position throughout the TUS examination and subsequent procedure.
Available equipment
The operator should ensure they are familiar with all the equipment that might be required during any intervention. This includes the procedural kit itself and the US machine being used. Most US machines offer a variety of modalities, of which conventional brightness (B)-mode will be sufficient for the majority of interventions; however, motion (M)-mode and colour flow Doppler scanning may provide additional information to those practitioners confident with their use and limitations.
If only one probe is available, this should be a low-frequency (2–5 MHz) curvilinear or phased array transducer, which allows a balance to be struck between image quality and the tissue penetration required for most thoracic work. A higher-frequency (6–12 MHz) linear probe sacrifices depth of view but provides high-resolution detail that can be of benefit when evaluating proximal chest wall structures (e.g. ribs, parietal pleura) and cervical or supraclavicular lymph nodes [17, 25, 26]. Again, if default modes are provided by the machine, these should be selected to suit the TUS examination being undertaken. “Abdominal” settings will suit work where more distal structures (e.g. pleural fluid, lung, mediastinum) must be assessed, whereas “vascular”, “musculoskeletal” or “thyroid” settings will favour proximal examinations.
The authors would encourage the reader to position the US probe parallel to the intercostal spaces when preparing for and performing interventions. While many clinicians hold the transducer in a longitudinal (vertical) plane across a number of rib spaces due to the advantages this provides in point-of-care TUS diagnostics (e.g. potentially greater sensitivity for detecting pneumothoraces), scanning in an individual rib space allows superior visualisation of the pleura and peripheral lung tumours. This parallel approach is also necessary to facilitate real-time (direct TUS) guidance of any transthoracic procedure. Regardless of the approach taken, it is crucial that any examination is systematic and allows the operator to build a three-dimensional model of the chest from images acquired in multiple sonographic planes [17, 25, 26]. Operators should report their TUS examination and any subsequent procedure in a structured fashion consistent with local recommendations and policy, as well as ensuring that a suitable number of labelled TUS images and/or clips have been recorded as supporting material.
Working environment and support staff
Interventional TUS and procedures will usually take place in a dedicated area (e.g. theatre, clean room) with staff who are familiar with each other and the interventions being performed. Standard operating procedures and bespoke safety checklists (figure 1) are likely to be in use as part of a wider risk-management strategy. This is rarely the case in emergency interventions undertaken on a ward and/or at the patient’s bedside; in these circumstances, the lead operator must consider the impact that the available space, monitoring facilities, sterility of the environment and expertise of support staff may have on procedural outcomes. In certain cases, a swift judgement may have to be made as to whether the risk posed by the immediate setting outweighs that of any delay incurred by moving the patient to a more familiar working environment.
Figure 1. Example of a pleural procedural safety checklist based on the World Health Organization (WHO) surgical safety checklist model. Figure provided by N.M. Rahman and J. Wrightson (Oxford University Hospitals NHS Foundation Trust, Oxford, UK).
Procedural technique
Following appropriate site selection, the practitioner must decide whether to perform a procedure using TUS in “real time” (i.e. under continuous direct sonographic vision, utilising either a bespoke needle guide mounted on the probe or a free-hand technique) or as an “US-assisted” intervention (i.e. marking a safe site as identified by TUS immediately prior to intervention). This choice is likely to depend on factors including operator expertise with either technique, and the size or complexity of the pleural collection being accessed. While there is no robust evidence that a “real-time” TUS technique improves either patient safety or procedural success when compared with an “US-assisted” approach, it does allow the operator to place their needle, guidewire and/or drain into a specific location. This can be of particular benefit in more complex septated collections where accessing the largest pocket of fluid possible is most desirable (figure 2).
Figure 2. a–d) Sonographic images demonstrating the use of real-time TUS guidance to access a septated pleural collection. US guidance is used to sequentially place the introducer needle (solid arrows) (b), the guidewire (dashed arrows) with J-tip (circled) (c) and the drain into the largest and most distal pocket. An agitated saline flush (d) can then be used to confirm the drain position as hyperechoic bubbles of air (circled) are seen entering and circulating within the pleural space. Figure reproduced with the kind permission of N.M. Rahman (Oxford University Hospitals NHS Foundation Trust, Oxford, UK).
“Real-time” procedures can be undertaken either out of plane (short axis), where the needle enters the skin away from the TUS probe and only the tip is aimed at and visualised within the plane of the sonographic window, or in plane (long axis), where the needle enters the skin at the side of the probe and traverses the sonographic plane, allowing the whole shaft to be visualised as the needle approaches the target area (figure 3). Either approach can be utilised by an experienced single operator holding the TUS probe in their nondominant hand and the needle in the other; sterile probe sheaths are also available that can help stabilise the needle’s position in relation to the probe during any intervention. The authors would encourage the use of an in-plane approach if possible, since it provides a clearer view throughout and therefore greater precision.
Figure 3. Demonstration of the relative positions of an US probe and needle during a) out-of-plane (short axis) and b) in-plane (long axis) procedures under real-time TUS guidance (insets). Figure reproduced with the kind permission of C.F.N. Koegelenberg (Tygerberg Academic Hospital, Cape Town, South Africa).
If an “US-assisted” technique is employed, any delay between TUS marking and subsequent pleural intervention should be kept to an absolute minimum (i.e. no more than a few minutes) with the patient’s position kept constant throughout. The use of a temporally and geographically remote “X marks the spot” approach for TUS assessment (e.g. in a radiology department) and subsequent pleural procedure (e.g. on a separate ward) is considered unsafe and strongly discouraged by the authors in light of published data suggesting that this is no better than a blind intervention [27, 28].
Basic interventions
For the purposes of this chapter, basic interventions are considered those that will be performed by the vast majority of, if not all, TUS practitioners, i.e. thoracocentesis (pleural aspiration) and tube thoracostomy (chest-drain insertion) for pleural fluid only. While there are published data to support a diagnostic role for TUS with respect to pneumothorax (PTX) (discussed in another chapter in this Monograph [29]), including as an iatrogenic complication of transthoracic interventions [30–32], it remains a largely binary test that cannot necessarily guide a clinician with respect to size or relative need for therapeutic intervention. As widely accepted guidelines do not advocate the use of TUS prior to intervention in the context of spontaneous PTX [17, 33–35], it is not felt to be appropriate for consideration in this chapter.
Initial considerations and site selection
There is a vast body of evidence demonstrating that the use of TUS prior to intervention for suspected pleural fluid substantially reduces the risk of either a failed “dry tap” or iatrogenic complications, including PTX or other visceral puncture; indeed, in expert hands, this risk approaches almost zero [11, 13, 14, 36]. Practitioners should, however, be alert to the possibility that TUS may instil false confidence and encourage them to stray outside the anatomical safe triangle (bordered anteriorly by the lateral edge of the pectoralis major, laterally by the lateral edge of the latissimus dorsi, inferiorly by the line of the fifth intercostal space and superiorly by the base of the axilla). With a patient sitting upright, a posterior intervention site may be considered more easily accessible due to the thoracic anatomy, which allows a greater apparent depth of fluid to be visualised under TUS as it accumulates in the costodiaphragmatic recess. However, this approach risks injuring the intercostal vessels, which may become exposed in the middle of the rib space with increasing proximity to the spine [37, 38]. There are published data to suggest that practitioners can sonographically screen for vulnerable vessels within individual rib spaces using colour Doppler, thereby potentially minimising the risk of causing an iatrogenic intrapleural bleed [39–41]; however, this work has not been either replicated on a larger scale or proven to improve patient outcomes in the context of what is already an infrequent complication. Neither does the use of US screening obviate good practice and anatomical landmarks; a needle should always be introduced immediately superior to the rib for safety reasons.
With the patient comfortably positioned, a thorough TUS examination should be undertaken in order to characterise the size and nature of the pleural collection to be sampled. A safe site for intervention should be identified, usually where there is a sufficient depth of fluid and no obvious incursion by either the lung or diaphragm during respiration. The distance between the skin surface and pleural space should be measured, particularly in more obese or oedematous patients, so that appropriate measures can be put in place where necessary. Whenever possible, thoracocentesis and tube thoracostomy should be undertaken in the anatomical safe triangle, or otherwise as laterally as the pleural collection will allow. If a more posterior approach is unavoidable, the patient’s consent should be obtained for the additional risk of vascular injury associated with this, and consideration given to the use of colour Doppler to screen for vulnerable intercostal vessels.
An aseptic (sterile) technique should be employed with the appropriate use of gowns, drapes, gloves and cleaning materials. Local anaesthetic should be administered to the chest wall, with particular attention paid to the skin and pleural surface where innervation is greatest; the use of a “real-time” technique allows the operator to confirm this visually on TUS as opposed to relying on informed guesswork. The point of entry to the pleural space should then always be immediately superior to the rib to minimise the risk of injury to the neurovascular bundle. Following any procedure, a further TUS assessment should be performed as standard and the findings documented. This allows the operator to exclude both iatrogenic PTX (identified as a loss of sonographic visualisation due to free air in the pleural space, with the subsequent absence of normal lung sliding or B-line artefacts) and intrapleural bleeding at the site of intervention (figure 4) [30–32, 42].
