Whereas some lesions are so apical that they do not move with respiration or are so large that they are nearly impossible to miss despite respiratory excursion, many lesions in the 1 to 2 cm range near the diaphragm may take more than 20 minutes of frustrated effort and multiple chest wall punctures attempting to align the biopsy needle with the target lesion prior to entering the lung. CT images for percutaneous lung lesion biopsy are usually only available as axial slices, and the CT machine often only images a 1 cm or so thick slab of tissue. A lesion near the diaphragm may easily move craniocaudal 4 to 5 cm over the course of a standard breath. Just asking the patient to "hold your breath" may not result in success. Even after pinpointing the small lesion within the slab of tissue and then inserting the needle at that level, the patient would need the opportunity to regain his breath so as to hold it again at the time of the needle thrust into the lung. Then the next time the patient holds his breath, he may have moved his torso or diaphragm differently enough that the lesion is no longer visible or that it is visible but a rib, fissure, or diaphragm is now in the line of the site, precluding safe entry. If a new skin entry site is then selected to account for the change, then the patient, not knowing what to do in order to aid the radiologist, may revert back to the first breath hold position on the subsequent breath. This process is made all the more difficult if the patient is sedated. The success or failure of the procedure may devolve into more a matter of chance than of logic or planning while striving for the moment when the needle is properly aligned so as to have a high probability of striking the lesion on the first thrust. Lesions with a higher technical challenge can be addressed in the following ways:

• Training the patient to breathe in a controlled fashion
• Positioning the patient to reduce the likelihood of motion and post-procedure air leak
• Choosing a target with the most desirable features

The Patient as Partner in Promoting a Successful Biopsy

More so than for other types of image-guided biopsies (in which there is neither a biopsy target that moves faster than the imaging machine nor a moderate risk of short-term hospitalization), it may be important prior to the day of the procedure to spend time explaining the usual biopsy experience to the patient and even simulating the experience.

Each patient is slightly different in his or her ability to follow instructions and hold a given position. Patients sent for lung biopsies are often debilitated, dyspneic, arthritic, hard of hearing, and sleep-deprived. Holding the same amount of air in the lungs on command is a feat that usually takes practice, even for healthy, highly intelligent persons. There are no known clinical trials that demonstrate that one technique to facilitate consistent breath holds is superior. Nevertheless, emphasizing to the patient his or her own role in contributing to a successful procedure and having the patient practice breath-holding and prolonged lying in the planned biopsy position theoretically will improve the chance of a successful outcome. Patients with dependence on 100% oxygen infusion, tracheostomies, phobias (such as to lying partially prone), and/or additional factors that would otherwise prevent successful percutaneous lung lesion biopsy can be trained to turn the moving target into a stationary target. Different methods work better for different patients, and detailed discussion of these methods is beyond the scope of this article.

Patient Position Effects

Chest wall motion is minimized by the prone position. The supine position is associated with moderate chest wall motion, while the lateral decubitus position is associated with the maximum chest wall motion.

True prone positioning is challenging unless there is specialized head support that enables comfortable breathing face down. A prone oblique position enables the head to be turned to one side and the arms placed below the level of the shoulders. It may be necessary to move the scapula for access. Prone position during biopsy has been associated with a lower risk for pneumothorax. [6]

Supine patients are often made more comfortable with a wedge under their knees. It may be necessary to tape a breast out of the way.

Lateral decubitus positions are the least desirable. Patients tend to drift out of this position over time, even if the hips and knees are bent for stability.

Patients are more comfortable with their arms at their sides. All positions should seek to eliminate cervical or other joint strain, pressure on "pressure points," and dyspnea, as these are problems that will result in patient motion increasing procedure duration and risks.

Choice of Target Lesion (in the setting of more than one potential target)

Size is often not the most important factor in selecting a target. A 1 cm pleura-based lesion may be safely directly accessed in the upper lung in a cooperative patient because the upper lung moves little with respiration. However, even a 1 cm lesion would be an undesirable target for a direct puncture in the lower lung because of the high likelihood of respiratory misregistration either at the moment of initial pleural puncture or at some point during the course of obtaining subsequent samples.

A large (in the craniocaudal dimension) lesion that either abuts the pleura or is visually distinct from but has adjacent airspace opacification extending to the pleura and which is demonstrated on prior PET-CT to be hypermetabolic is the ideal lesion for percutaneous lung lesion biopsy. The size improves the chance of striking the target. The craniocaudal lesion size is more important than other lesion dimensions (especially if the procedure is performed using a machine that does not have real-time CT fluoroscopy), as that is the dimension that will determine how likely it will be to keep the lesion in the field of view on the imaging monitor during the procedure. A peripheral location in the thorax reduces the chance of striking larger vessels and the chance for needle drift/inadvertent redirection during insertion. The ability to avoid aerated lung on entry diminishes the odds of pneumothorax. A higher metabolic activity increases the chance that viable abnormal tissue will be obtained.

When a lesion large in the craniocaudal dimension is not available as a target, the next most ideal location is one that neither abuts the pleura nor is central (allowing room for needle redirection after a possible inadvertent initial pleural puncture without withdrawing the needle through the pleura, but avoiding proximity to larger central vessels).

The most mobile part of the lung is peridiaphragmatic. The part of the lung most difficult to expand after a pneumothorax is the lung apex. A lesion in the upper region of the lower lobe is preferable to peridiaphragmatic and apical lesions, in that this part of the lung moves little with respiration and because the lower lobe can undergo compression with gravity in the supine position after the procedure to prevent or reduce a pleural air leak.

In a patient with multiple lesions and prior invasive thoracic procedure, the side on which prior surgery was performed should be selected for biopsy. Pleural adherence can increase due to scarring and reduce the chance of a pneumothorax. Puncturing via the thoracotomy scar itself should be avoided, however, because the hard tissue can interfere with needle manipulation.

It cannot be stressed enough that the morphology of the area of concern is a key feature when contemplating lung biopsy. Benign round atelectasis or even "standard non-round atelectasis" can fit of all of the criteria of the optimal "lesion" as described above, including that of being very hypermetabolic on PET, as could a region of parenchymal fibrosis. However, biopsying such abnormalities either with or without an actually associated mass almost never yields clinical benefit. Only true nodules/masses are likely to yield any useful material on pathologic review.

Some scenarios have a probability of failing (with or without the need for emergent surgery) that is more probable than not (i.e., risks outweigh likely benefits).

• Small immediately subpleural lesions make it very difficult to time needle entry so as to pierce these lesions on the first attempt and to keep the introducer needle in the lesion over the course of obtaining multiple samples (increasing risk for pneumothorax).
• Small lesions touching the heart are usually unsuitable for biopsy. Cardiac motion on the lesion increases the risk of missing the lesion while placing the patient at high risk for pericardial/myocardial puncture followed by tamponade and death.
• Nodules along fissures (particularly in the superior portion of the right middle lobe just under the minor dome-shaped fissure) can be difficult to target without puncturing a second lobe (thereby making two additional pleural punctures inadvertently) even with the benefit of an angled CT gantry.
• Small lesions deep in the costophrenic sulci move a great deal. Inadvertent puncture of the diaphragm (which can be very painful even if there is not associated puncture of an immediately underlying structure such as liver or spleen) is a likely sequela.
• Ground glass or largely necrotic lesions where the viable cellular yield is likely to be too low from needle sampling to enable a diagnosis. The smaller the lesion, the more unlikely it is to yield diagnostic material. Nodules as small as 4 mm have yielded enough tissue for a pathologist to feel confident to diagnose nonsmall cell lung cancer [7], but size in and of itself is not a reliable indicator of success. Molecular testing agencies may require at least 100 viable tumor cells (author's experience), and no study has been published that equates a number of viable tumor cells to lesion size.

In these situations, either planning to offer thoracoscopic biopsy post-percutaneous lung lesion biopsy the same day or next day service or proceeding straight to thoracoscopic sampling with all its inherent risks is the proper route.

A coaxial technique of inserting a thinner sampling needle through a larger needle placed at the edge of the lesion has a number of theoretical advantages over tandem punctures. A number of samples can be obtained without re-puncturing the pleura (until such time as the introducer needle lumen develops a high degree of friction from the accumulation of coagulated blood). This theoretically improves speed and reduces pain and puncture-related complications. The depth of the sampling passes can be planned, and the stiffer, larger needle can enable additional torque and better steerability during manipulation. If a pneumothorax does occur, the introducer needle often will remain lodged in the lesion, allowing further samples to be obtained. A properly selected larger-bore needle can be used to obtain a biopsy gun specimen, insert a marker into the lesion for thoracoscopic resection or radiation therapy, or deliver a substance to caulk the tract (discussed below).

Each puncture site has a certain pressure above which air will leak into the pleural space. Performing a single puncture decreases the chances that one will leak at a relatively low intrathoracic pressure and cause a pneumothorax. Most small puncture wounds to the pleura leak at 10-40 mm Hg. A coughing fit will generate pressure in excess of 100 mm Hg, due to which all nonpatched and probably most patched punctures would leak. Visible tearing of the pleura allows leakage at a pressure of 1-2 mm Hg. [8]

A single puncture non-coaxial approach should be considered for high-risk circumstances, such as for a transcaval or trans brachiocephalic vein approach for lesions known to have hemorrhaged or suspected to be at high risk for hemorrhage and lesions with an associated prominent internal air-bronchogram in which there is an increased risk of air embolism.

Breath Holding

Respiratory volume should remain within the range of normal, quiet breathing. A puncture during a deep inspiration or expiration results in tension on the needle when the lung returns to its more normal status. This theoretically places greater stress on the pleura at the puncture site increasing the likelihood of a pleural tear. During sampling, care should be made not to create tension on the needle; ideally, the patient holds his/her breath while the radiologist is sampling. Patients are better able to hold a breath in inspiration than in expiration. Once a person can no longer hold breath, the tendency is to exhale if an inspiration was held but to inhale if an expiration was held. The latter is more likely to cause an air embolism.

Precautions

Minimizing the time that a needle is crossing the pleural space

If the needle is allowed to move with the motion of normal respiration, usually, no harm occurs. However, as the duration of the procedure increases, patients are eventually bound to move due to discomfort, to cough, or to place themselves at risk from needle motion otherwise. Delays, such as prolonging time to review the adequacy of tissue samples, from imaging to detect clinically silent intrathoracic complications or from personnel in the room not having proper radiation safety equipment, should be reduced to the absolute minimum.

Cough Suppression

Forceful coughing is likely to tear the pleura. Dramatic negative intrathoracic pressure occurs during inspiration prior to a cough, and high positive intrathoracic pressure occurs during a cough. This places the patient at risk for pneumothorax and for air embolism should the needle be uncovered with the tip in a vein. Procedure progress is halted during coughing episodes. Cough suppressant medication should be administered, or the irritant addressed. Otherwise, the procedure should be terminated.

Lung/Pleural Patch Technique

This technique entails caulking the pleural defect via the introducer needle at the completion of the procedure to prevent puncture site gas leakage. Different materials may be used, but the traditional approach involves using the patient’s own blood. If aerated lung has not been violated, a blood patch is not necessary. If multiple punctures have been made or a pneumothorax has already developed, then a blood patch theoretically is of lesser value. While the technique has been effective in lung biopsy models and and in real patients [8], no randomized trials comparing different types of blood patch techniques have been performed.

Post Procedure 

After blood patch placement and needle removal, some physicians roll the patient into the puncture-site-down position. This initial repositioning event should be performed by as many assistants as necessary to ensure that the patient remains passive and does not strain or perform a Valsalva maneuver. A forceful Valsalva maneuver is less likely to occur if the roll is performed while the patient lets his or her breath out. The needle removal and the rolling should take no more than a few seconds. Puncture-site-down positioning was first suggested by Zidulka in 1982. [9] It may work from a physiologic and/or mechanical mechanism. Physiologically, it makes the periphery of the dependent lung atelectatic, which should reduce local aeration. Mechanically, it tamponades the tract by creating visceral-parietal pleural apposition.

It is theoretically beneficial to prevent all activities that may elevate intrathoracic pressure, such as any type of breathing requiring the use of accessory muscles (e.g., laughing) or straining (e.g., sitting up in bed without assistance).

Oxygen saturation should be monitored. Supplemental oxygen interferes with this method of following the clinical impact of a small pneumothorax, so it should only be used when necessary. If a pneumothorax is known to be present, oxygen may be administered to facilitate resorption of the existing pneumothorax. The premise for how this may help is that a higher partial pressure of oxygen speeds diffusive resorption of trapped pleural air, which is comprised mostly of nitrogen (and carbon dioxide).

Follow-up Imaging

No chest radiograph need be obtained immediately after the biopsy unless symptoms or a falling oxygen saturation level suggest that a pneumothorax is present. Despite the best intentions of the technologist, the performance of a radiograph will probably entail at least some degree of patient straining or Valsalva maneuver. Oxygen saturation levels provide enough clinical information to delay the acquisition of the first image.

On the other hand, if an initially subclinical problem does exist, it is best to know about it before discharge. After several hours in the puncture-site-down position, the patient should be permitted to test activities similar to those that he or she would perform at home. A chest x-ray is then obtained. Upright expiratory images in at least two views (e.g., frontal and oblique) provide the most sensitive method for detecting interpleural air via plain film radiography. In the absence of serial images, new or continuing leakage cannot be distinguished from leakage that occurred immediately after the procedure and then stopped. Thus, follow-up imaging after the initial discovery of a pneumothorax should be made to determine leak stability.

Patient Discharge

The decision to discharge a patient, as opposed to admitting for observation or treatment, depends on the patient's condition, home situation, and home location. If there is more than a trivial pneumothorax or minor physical symptoms or signs, then only the following patients are candidates for discharge, given the small risk of death (e.g., from tension pneumothorax):

• Can tolerate a larger pneumothorax,
• Have a responsible family member who will be staying the night with the patient, and
• Lives within range of transport to a medical facility or arrival of an ambulance within 10 to 15 minutes of symptom onset.

Percutaneous lung lesion biopsy is among the highest complication rate procedures performed by radiologists. The SIR suggests a threshold of up to 45% and 20% for pneumothorax rate and a chest tube insertion rate, respectively, prior to the trigger of a departmental review for creating a plan to lower the frequency of these complications. [4] The creators of the Johns Hopkins Surgical Risk Scale deemed percutaneous lung lesion biopsy a level 2 procedure due to it being a higher risk procedure than bronchoscopic biopsy, which is level 1. Not only is the chance of pneumothorax and hemorrhage lower with bronchoscopic biopsy, but the patient's airway is already secured from obstruction, which is not the case with percutaneous lung lesion biopsy. Percutaneous lung lesion biopsy is often performed on persons who are obese, elderly, highly emphysematous, and/or are ASA category 4 patients (e.g., patients who are unable to walk up a flight of stairs). Pre-notification of consultant medical specialists (e.g., an interventional pulmonologist or respiratory therapist) to be available on call at the first sign of trouble is prudent in cases where patients have these risk factors.

Deaths have occurred from percutaneous lung lesion biopsy. The mechanism of death is usually secondary to hemorrhage (all comer rate of about 1%, air embolism (all comer rate of less than 1%), cardiac event, or tension pneumothorax. [10] The SIR recommends a less than 3% threshold for "prolonged" hospital admission, having to exchange the chest tube, and/or pleurodesis [4], even though these decisions are usually outside of the radiologist's unilateral choice.

Pneumothorax

Pain from pneumothorax is not a consistent phenomenon across patients. Patients often experience pleuritic chest pain with a new even relatively small pneumothorax, although some patients are asymptomatic until a fairly impressive pneumothorax develops. The size of pneumothorax necessary to cause shortness of breath is extremely variable and depends on the underlying condition of the lungs. 

If a pneumothorax occurs prior to completion of tissue retrieval, the lung may need to be reinflated as the next step. Even notwithstanding a patient's clinical deterioration, if the no-longer-fixed-in-position lung does not move in a predictable manner, it may be impossible to anticipate the target lesion's future position at the time of next needle advancement. Also, the lung only may be able to be balloted, rather than punctured, by needle thrusts.

If air leakage is discovered during procedure follow-up, a minimum additional hour of puncture site-down positioning should be performed. Once imaging has shown that leakage has stopped, a period of upright positioning should be tried, followed either by discharge if no leakage occurs or repeating the cycle if leakage recurs. The cycle continues until the patient

1. Can be discharged or
2. Requires pleural drainage due to

• Symptoms,
• A pneumothorax exceeding about 30% [8], or
• A recurring pattern of leakage.

Visual-only estimates of percent pneumothorax tend to be unreliable. The actual percent stenosis should be estimated using calipers and an evidence-based formula. [11] A pneumothorax that tracks down the lateral aspect of the chest will likely require evacuation.

Aspiration only of a pneumothorax may prevent chest tube placement in at least some patients with a substantial pneumothorax. Small gauge catheters (as small as 4 French) can be used inserted either via Seldinger or trocar technique. Alternatively, a large gauge needle (e.g., a Hawkins-Akins needle, which is a non-sharp needle with a sharp trocar) can be used. A pneumothorax can be evacuated most quickly via wall suction. Aspiration can also be used intentionally only to re-expand the lung temporarily (such as in the case of posterior-approach percutaneous lung lesion biopsy) thereby allowing for a catheter to be placed under less emergent conditions in a separate predetermined location for long-term use.

Hemoptysis 

Hemoptysis may be more likely to occur if puncturing a pulmonary cavity or enlarged bronchus, which are both associated with bronchial artery hypertrophy. Unusually bloody specimens, blood dripping out the introducer needle, and the formation of ground-glass attenuation in the lung prognosis the possible development of clinically significant hemoptysis.

If these findings develop, then less aggressive biopsy manipulations are recommended. Oxygen should be applied. The patient can be placed biopsy side down to prevent blood dripping through the bronchi into the other lung. Intubation if necessary should be performed with a dual lumen tube. If these maneuvers do not work, then consultation should be obtained for bronchoscopic tamponade of the lobar bronchus. Other therapies to consider include bronchial artery embolization, pulmonary artery embolization, and surgery.

If the patient had a decreased hemoglobin level or fluid volume to begin with, then administration of blood and/or IV fluids should be performed.

Air Embolism

Air embolism may occur from inspiration by the patient when the trocar has been removed from a needle tip located in a pulmonary vein and/or 2) iatrogenic creation of a bronchovenous fistula. The patient may become unconscious, have signs of a stroke, or undergo a seizure. 

The patient should be placed in the left lateral decubitus and/or Trendelenburg position to prevent air from exiting the left atrium prior to dissolving. Oxygen should be given to facilitate absorption of nitrogen in the bubbles.

Intubation and positive pressure ventilation may worsen venous air introduction in a bronchopleural fistula. Although most hospitals do not have decompression/hyperbaric chambers, if one were available this would be an appropriate time to use it.

The Centers for Disease Control (CDC) the United States 2015 Cancer Statistics cites lung cancer as, by far, the most common cause of cancer death in the United States. Multiple society guidelines recommend that cancer treatment decisions be based on tumor histologic type and molecular markers. Although exceptions can be made, tissue diagnosis is the general rule prior to both curative and palliative therapy.

However, just as it is good medical care for physicians to see patients as persons and not as diseases, it is important for clinicians to understand that in order for tissue diagnosis to be obtained, biopsy procedures often require special considerations regarding the person undergoing the biopsy. The patient may not be able to lie still long enough to create an accessible avenue for the needle, may not be able to hold his/her breath consistently enough to enable access to the moving lesion given limitations in a hospital's CT fluoroscopy equipment, or may warrant specialist consultation to optimize pre-biopsy and post-biopsy care to prevent prolonged hospitalization or even severe permanent injury secondary to complications.

For these reasons and because most experienced interventional radiologists can reach a target of at least 5 mm diameter and less than 15 depth, the commonly asked question "Can the lesion be biopsied?" is generally not an appropriate question. The following three questions are more appropriate to decision making for patient care:

• "Has the lesion reached a size allowing a reasonable chance at a tissue yield or is it more reasonable to wait to allow the lesion to grow in anticipation that a diagnosis will still likely be achieved prior to potential metastasis?"
• "Assuming that biopsy now appropriate, how should the physicians and patient work together to optimize the patient medically and psychologically to improve the likelihood of a safe and successful biopsy?"
• "Anticipating that the biopsy attempt may not yield an adequate amount of tissue, what will plan B be?"

HEALTHCARE TEAM

A percutaneous lung lesion biopsy is usually performed by a radiologist, but complete care of the patient also involves nurses and radiologic technologists and may involve surgeons, pulmonologists, and other medical specialists assisting the surgeon in preparation and education of the patient. During and after the procedure, the specialty-trained radiology nurse assists the radiologist and monitors the patient reporting any destabilization of vital signs. The nurse should also assist in providing coordinated patient education. A team approach to the care of these patients will lead to the best outcomes. [Level 5]

OUTCOMES SUMMARY

Percutaneous lung lesion biopsies have a high likelihood of diagnostic success and in most cases are without complication.  However, a sizeable number of patients will experience one or more complications and/or failure of the procedure.  Hence, patients should be educated in advance about such possibilities and ways they can help reduce the possibilities, and patients must be closely monitored during and after the procedure.

The role of the nurse is important after the procedure. Because there is always a risk for a hemothorax or pneumothorax, the nurse should assess the pulmonary status in the recovery room. In addition, if there is a Heimlich valve or a drainage tube, the nurse should ensure that it is patent and functioning. Any drainage should be recorded. The nurse should look at the chest x-ray report to determine if there is a pneumothorax present.

Vitals signs including pulse oximetry should be monitored for several hours after the procedure. The chest should be auscultated and output from any chest drain should be recorded. Patients who are discharged with a Heimlich valve should be educated on how to maintain it and when to return back to the surgeon.