Chapter 36. Pericardiocentesis

Pericardiocentesis is the removal of fluid from the pericardial space surrounding the heart. The fluid is usually aspirated with a needle and syringe. Occasionally, a catheter is placed within the pericardium or a surgical approach is used. This may be performed for diagnosis, to obtain pericardial fluid; to relieve a pericardial effusion and improve cardiac output; or as a lifesaving measure to relieve a cardiac tamponade. The technique is relatively simple to perform yet has a significant rate of complications.

Since humanity's earliest times, penetrating cardiac injuries have held a dramatic place in both romantic and medical literature.1–8 In 1649, Riolanus first described pericardial tamponade.3 He noted that an abundance of moisture is collected therein [the pericardium], which causes suffocation, and overwhelms the heart. In 1827, Thomas Jowett described the first use of pericardiocentesis as an intervention for pericarditis.4 In 1829, Baron Larrey, Napoleon's Surgeon, is reported to have performed the first successful pericardiocentesis.5 By 1939, Bigger had suggested that some patients with cardiac tamponade could be managed with pericardial tubes alone, with prompt operation for recurrence.7

Anatomy of the Heart and Pericardium

The pericardium is an inverted cone-shaped sack surrounding the heart and lying on top of the diaphragm (Figure 36-1). The inner portion, or visceral pericardium, is a single layer of mesothelial cells covering the epicardium. The outer layer is composed of a dense outer fibrous tissue with an inner layer of mesothelial cells known as the parietal pericardium. The fibrous pericardium is attached to the central tendinous portion of the diaphragm inferiorly. Superiorly, the outer fibrous layer blends with the sheath covering the great vessels. Anteriorly, it attaches to the posterior surface of the sternum. Posteriorly, it is attached to the thoracic vertebral column, esophagus, bronchi, and aorta.

The heart is contained within the pericardial sac (Figure 36-1B). Numerous portions of the heart are exposed behind the anterior chest wall (Figure 36-2). This includes the right ventricle, left ventricle, right atrium, left atrium, aorta, pulmonary artery, and inferior vena cava (IVC). These structures are vulnerable to injury behind the anterior chest wall9,10 (Table 36-1). The surface area that each of these structures contributes to the anterior cardiac silhouette is also listed in this table. These numbers reflect, roughly, the anatomic incidence of injury with cardiac trauma.11 Traumatic injury to any of these structures can result in a pericardial effusion and cardiac tamponade.

The pericardial cavity is a potential space between the visceral and parietal layers of the pericardium. Up to 50 mL of fluid is normally contained within this space. The fluid acts as a lubricant to the motion of the heart. Accumulation of fluid in the pericardial space requiring drainage can have a variety of etiologies. From a review of several retrospective series, the estimated causes and relative frequencies of pericardial effusions are listed in Table 36-2.12–18

Cardiac tamponade is a life-threatening condition that must be diagnosed and treated emergently. The diagnosis of cardiac tamponade is primarily clinical. It may easily be overlooked unless a high index of suspicion is maintained in both medical and trauma patients. Sauer and Murdock describe a “danger zone” for penetrating torso trauma19 (Figure 36-3). The superior border is bounded by a line through the sternal notch. The lateral borders are bound by a line through the midclavicle. The inferior border is identified by a line through the epigastric area. Any penetrating injury in the danger zone or through it has the potential to cause a cardiac injury and pericardial tamponade.

Pathophysiology of Cardiac Tamponade

The clinical effects of cardiac tamponade occur due to accumulation of fluid under pressure in the pericardial space. This space can become quite large over time. In some chronic disease states, pericardial effusions of 1 to 2 L can occur without signs of cardiac tamponade.14,20 The ability of the pericardial sac to acutely stretch is limited. Estimates of the volume of fluid required to acutely accumulate and produce a cardiac tamponade range from 60 to 200 mL.

Cardiac tamponade should always be considered as a cause of shock in the medical patient. This includes patients who are taking oral or parenteral anticoagulants, have known cancer, have known pericardial disease, are suspected of having an aortic dissection, or have had a recent myocardial infarction. Cardiac tamponade can also be due to iatrogenic causes, including central venous line placement, transthoracic cardiac pacing, transvenous cardiac pacing, and cardiopulmonary resuscitation.

The pressure–volume relationship between the size of the pericardial effusion and the pressure imposed on the cardiac chambers is exponential. The initial accumulation of fluid produces little or no clinical effect. The initial physiologic strategies of compensation include an increase in the systemic venous pressure, catecholamine release, and tachycardia. At some point, the ability of the pericardial space to distend and accommodate more fluid is overwhelmed. From this point on, even small amounts of fluid generate significant and increasing pressure on the heart chambers. As the pericardial pressure rises, venous filling of the right heart is drastically impaired. The interventricular septum bulges into the left ventricle. Left ventricular filling becomes compromised from the lack of flow from the right ventricle and the bulging inward of the interventricular septum. Eventually, cardiac perfusion decreases, the heart suffers injury, and the patient goes into a state of shock.

A progressive decline in cardiac output occurs as pericardial fluid accumulates and intrapericardial pressure increases.21 Initially, the right atrial pressure is greater than the intrapericardial pressure as the body compensates by increasing venous return. This is followed by the equilibration of the right atrial and intrapericardial pressures. Eventually, as the heart chambers cannot achieve a pressure lower than the surrounding pericardial fluid pressure, equilibration of diastolic pressure in each heart chamber occurs and produces the greatest drop in cardiac output. As the intrapericardial pressure continues to increase, the cardiac chambers collapse, resulting in intractable hypotension and death. The disproportionate effects of the later accumulation of small amounts of fluid explain why withdrawal of even a small amount of fluid from the pericardial cavity can produce dramatic temporary improvements in the clinical status of the patient. It also explains why “monitoring” patients for the evolution of cardiac tamponade with central venous pressure lines is dangerous, as the patient will proceed from stable and compensated to profoundly unstable quite suddenly.

Patient Evaluation

Several clinical findings are associated with cardiac tamponade. Beck's triad of muffled heart sounds, hypotension, and jugular venous distention is associated with cardiac tamponade. Almost all patients with cardiac tamponade will have at least one of these signs. Unfortunately, very few patients with cardiac tamponade will have all three signs. Beck's triad has been found in only up to 40% of patients with cardiac tamponade.22 These findings may be absent if the patient is hypovolemic due to hemorrhage. Restlessness, fatigue, tachycardia, and tachypnea are often present. These can progress to shock, coma, and eventually death.

Changes in the jugulovenous waveforms may be seen in cardiac tamponade. Instead of the normal systolic X descent and diastolic Y descent, only the systolic X descent occurs in cardiac tamponade. This is a result of the increased diastolic pressure being exerted by the accumulating pericardial fluid. The only time the right heart can fill is during systole, when the internal volume of the heart is reduced. The changes in the jugulovenous waveforms cannot be evaluated in the supine and/or immobilized trauma patient.

Kussmaul's two signs, paradoxical increase of the jugulovenous pressure during inspiration and pulsus paradoxus, may be seen in patients with cardiac tamponade. Pulsus paradoxus is a drop in systolic blood pressure of ≥10 mmHg during inspiration. To measure this, inflate the blood pressure cuff until the cuff pressure is greater than the patent's systolic pressure. Slowly release the cuff pressure until beats are heard only during expiration. Keep deflating the cuff pressure until beats are heard continuously in both inspiration and expiration. The difference between these two physiologic points is the amount of pulsus paradoxus. This normal physiologic finding is exaggerated by the accumulation of pericardial fluid, forcing the right heart and interventricular septum into the left ventricle.

Electrocardiographic and radiographic signs of cardiac tamponade are often not present. Changes on the electrocardiogram (ECG) may be present in patients with cardiac tamponade. A pericardial effusion surrounding the heart, if large enough, can result in a “low voltage” ECG tracing. Electrical alternans is a change in the morphology or amplitude of the QRS complexes on the ECG as the heart swings to and fro within the pericardial fluid (Figure 36-4). It may be associated with pericardial tamponade but is not pathognomonic. Pulseless electrical activity (PEA) in the absence of hypovolemia or a tension pneumothorax is highly suggestive of cardiac tamponade. Opinions differ as to the clinical significance of these findings. The finding of an enlarged cardiac silhouette on a chest radiograph may be useful in chronic pericardial effusions but is usually absent or nonspecific in the acute setting.

Traumatic cardiac tamponade can be caused by a variety of agents and etiologies. This includes bullets, knives, ice picks, displaced fractured ribs, central venous line placement, pacemaker insertion, pericardiocentesis, intracardiac injection, surgery, migrating pins or needles, nails ejected from machinery, and venous bullet embolization. Cardiac tamponade is the most common presentation of penetrating cardiac injuries overall. It occurs in 80% to 90% of stab wounds and 20% of gunshot wounds.11

Cardiac ultrasound has become the diagnostic procedure of choice to identify cardiac tamponade (Table 36-3). A prospective study showed that bedside ultrasound performed by Emergency Physicians and Trauma Surgeons was 96% accurate and 90% sensitive.23 Cardiac ultrasonography performed on trauma patients can be 98% to 100% accurate and sensitive in diagnosing pericardial fluid and cardiac tamponade.22,24–27 The series of 261 patients had no false negatives. Other studies have demonstrated false-negative rates in the range of 5% to 40%.19,28,29

Bedside ultrasound can rapidly confirm a suspected pericardial effusion or cardiac tamponade and guide drainage. Blind pericardiocentesis has a complication rate as high as 50%, and an associated mortality.15,16,30 Ultrasound-guided pericardiocentesis can decrease the rate of complications by allowing visualization and avoidance of adjacent anatomic structures. This increased safety factor is supported by multiple studies from the cardiology literature.31–33

Other ultrasonographic findings in pericardial tamponade include a swinging heart, collapse of the right and left ventricular chambers, and marked inspiratory changes in ventricular dimensions.10 Some authors advocate using transesophageal echocardiography, even in unstable patients, because of its superior imaging when compared to transthoracic echocardiography.34 Other methods of imaging the pericardium include computed tomography (CT), helical CT, and magnetic resonance imaging. These modalities should be used only for stable patients in whom the diagnosis of a pericardial effusion and not cardiac tamponade is being considered.

Significant controversy exists over the role of pericardiocentesis.9 The only indication for emergent pericardiocentesis would be in a patient in whom the life-threatening physiologic changes of cardiac tamponade were present and the diagnosis was consistent with known prior disease, a traumatic mechanism of injury, or a bedside Emergency Department ultrasound demonstrating a pericardial effusion and/or cardiac tamponade. Pericardiocentesis is also performed in the cardiac catheterization laboratory or the intensive care unit to obtain pericardial fluid for diagnostic testing. It may also be performed in a cardiac arrest patient with PEA when other etiologies for PEA have been ruled out or a pericardial effusion is seen on ultrasonography.

There are no absolute contraindications to performing a pericardiocentesis in the unstable patient with signs of cardiac tamponade. Uncorrected bleeding disorders in a stable medical patient would be an absolute contraindication to performing the procedure. Small, loculated, or posteriorly located effusions in a stable patient are also considered contraindications. It is also contraindicated in cardiac tamponade associated with an aortic dissection.35

While the dramatic beneficial effects of withdrawing even a small amount of pericardial fluid are well documented, many authors feel that there is little or no role for pericardiocentesis in the trauma patient. These authors argue that once the diagnosis of a pericardial effusion is made, the patient should receive a prompt sternotomy.11 If the patient is too unstable for transport to the operating room, an emergent thoracotomy should be performed. Aggressive fluid replacement with crystalloid and blood products, as well as performing a needle thoracostomy (Chapter 38) to rule out a tension pneumothorax before a pericardiocentesis is contemplated in the trauma patient.36

Pericardiocentesis

• Povidone iodine or chlorhexidine solution
• Sterile gloves and gown
• Face mask with eye shield or goggles
• Local anesthetic solution (1% lidocaine)
• 25 gauge needle, 5/8 in. long
• 18 gauge needle, 1½ in. long
• Syringes (10, 20, and 60 mL)
• Sterile drapes
• Towel clips
• 16 to 18 gauge spinal needle or catheter-over-the-needle, 7.5 to 12.5 cm long
• 18 to 20 gauge spinal needle or catheter-over-the-needle, 3.75 cm long
• #11 scalpel blade
• 4 × 4 gauze squares
• Alligator clips connected by a wire
• Collection basin
• ECG monitor
• J-tipped guidewire, 0.035 mm in diameter
• Size 6 to 10 French flexible multihole catheter, 5 to 6 in long, with or without a pigtail
• Three-way stopcock
• Plastic tubing
• Ultrasound machine
• 3.5 to 5.0 MHz phased-array or curvilinear ultrasound probe
• Sterile ultrasound probe cover (can be a sterile glove)
• Sterile ultrasound gel
• Variable-angle needle guide attachment if available
• Nasogastric tube

Subxiphoid Pericardial Window

• Electrocautery set
• Forceps
• Small retractor
• Small rib spreaders
• Sutures, 2-0 Vicryl and 3-0 nylon
• Sterile suction device
• Yankauer suction catheter
• Suction tubing

Most Emergency Departments do not have single guidewires and 6 to 10 French flexible catheters readily available to use for a pericardiocentesis. A commercially produced pericardiocentesis kit is available from numerous manufacturers and contains all the required equipment (e.g., Merit Medical, South Jordan, UT; Boston Scientific, Natick, MA). In an emergency situation, a 6 to 10 French single-lumen central venous line access kit may be substituted.

Explain the procedure, its risks, and benefits to the patient and/or their representative if time and the patient's clinical condition permit. A signed consent is not necessary as this is an emergent procedure. If possible, place the patient semirecumbent at a 30° to 45° angle (Figure 36-5). This position brings the heart closer to the anterior chest wall. The supine position is an acceptable alternative. Assess the patient for any mediastinal shift by physical examination and chest radiography (if time permits). Apply the cardiac monitor, pulse oximeter, and supplemental oxygen to the patient. While the placement of an arterial line is ideal, such a line may not be available. Place the noninvasive blood pressure cuff on the patient's arm. Insert a nasogastric tube to decompress the stomach and decrease the possibility of gastric perforation during the procedure.

Identify the anatomic landmarks necessary to perform this procedure. The needle can be inserted at numerous sites (Figure 36-6). These include the following: below the xiphoid process, at the right sternocostal margin, at the left sternocostal margin (subxiphoid approach), in the left or right fifth intercostal space parasternally (parasternal approach), or in the left fifth intercostal space at the midclavicular line (apical approach). The most commonly used site is at the left sternocostal margin or the subxiphoid approach. This is the approach described throughout the “Techniques” section of this chapter.

Surgically prepare the xiphoid and subxiphoid areas. Clean any dirt, debris, and fluid from the area. Apply povidone iodine or chlorhexidine solution to the xiphoid and subxiphoid areas and allow it to dry. Apply sterile drapes to delineate a sterile surgical field. Reidentify the anatomic landmarks. If the patient is awake, anesthetize the needle tract with local anesthetic solution. Place a subcutaneous wheal of local anesthetic solution at the site chosen to insert the needle. Inject local anesthetic solution through the skin wheal and into the subcutaneous and muscular tissues of the wall of the torso.

Prepare the equipment. Set up a sterile field on a bedside table. Open all required equipment and place it on the sterile field. The Emergency Physician should wear full personal protective equipment to protect themselves from contact with the patient's blood and body fluids. While time is of the essence and this is an emergent procedure, aseptic technique should be followed. Attach the spinal needle onto a 20 mL syringe containing 5 mL of sterile saline.

Blind Insertion Technique

Puncture the skin with a # 11 scalpel blade between the xiphoid process and the left costal margin. Grasp the syringe with the dominant hand. Insert the spinal needle through the skin incision and at a 45° angle to the midsagittal plane (Figure 36-7A) and at a 45° angle to the abdominal wall (Figure 36-7B). Aim the tip of the spinal needle toward the patient's left shoulder (Figure 36-7A). Alternatively, the spinal needle can be aimed toward the patient's left midclavicle, right midclavicle, or sternal notch to theoretically lessen the chance of iatrogenic damage to the coronary arteries.

Advance the spinal needle 4 to 5 cm while applying negative pressure to the syringe and observing the cardiac monitor. Inject 0.25 to 0.50 mL of saline occasionally to ensure that the needle remains patent while advancing the needle. Continue advancing the spinal needle while applying negative pressure until there is a return of blood, cardiac pulsations are felt, or an abrupt change in the ECG waveform occurs. If the ECG waveform shows an injury pattern, withdraw the needle in 1 to 2 mm increments until the ECG pattern normalizes. This indicates that the needle is touching or has penetrated the myocardium. Stop advancing the needle.

Aspirate with the syringe. If a large volume of blood is quickly and easily withdrawn, it often means that the tip of the spinal needle is within the ventricle. Techniques to confirm the intraventricular placement of the needle tip have been described and include the following: observing that the aspirate does not form a clot, comparing the patient's hemoglobin to that of the aspirate, injecting fluorescein and looking for a fluorescent flush under the skin of the eyelids, or injecting 3 mL of dehydrocholic acid (decholin) and asking whether the patient experiences a bitter taste. These are time-consuming and less reliable than ultrasound, if available.

When the pericardial space is entered and fluid is aspirated, there should be a marked improvement in the patient's clinical status. The procedure can be terminated at this point. Alternatively, the Emergency Physician may want to withdraw as much fluid as possible. When the syringe is filled with fluid, stop withdrawing the plunger. Stabilize the spinal needle against the patient's torso and remove the syringe. Replace the syringe with a new one and continue the procedure. Alternatively, attach a three-way stopcock between the spinal needle and the syringe. Attach intravenous extension tubing to the stopcock. An assistant can open and close the stopcock while the physician aspirates fluid and ejects it through the intravenous extension tubing and into a basin. As the pericardial space is drained, the epicardium will approach the needle tip. If an injury pattern appears on the cardiac monitor, withdraw the needle slightly and continue to aspirate fluid. Remove the needle when fluid can no longer be aspirated.

ECG-Monitored Technique

The purpose of ECG monitoring is to prevent accidental ventricular puncture with the spinal needle. Attach one alligator clip to the base of the spinal needle and the other to the V1 lead of the ECG machine or cardiac monitor (Figure 36-8). The V1 lead will serve as an active electrode based at the tip of the spinal needle. As the spinal needle is advanced, an injury pattern noted by ST-segment elevation will be seen if the myocardium is contacted or penetrated by the spinal needle. The presence of a premature ventricular contraction or a ventricular arrhythmia can also signify contact with the myocardium.

Prepare the patient as previously described. Prepare the equipment (Figure 36-8). Turn on the ECG machine or cardiac monitor. Insert and advance the spinal needle, as described previously, while observing the ECG monitor or cardiac monitor. If an injury pattern or premature ventricular complexes are seen, withdraw the needle in 1 to 2 mm increments until the injury pattern disappears. Aspirate the pericardial fluid as described in the preceding section.

Seldinger Technique

An indwelling catheter may be placed in the pericardial cavity to drain the pericardial fluid (Figure 36-9). This may be done in cases of medical or traumatic pericardial effusions, since the pericardial fluid often reaccumulates. An indwelling catheter allows intermittent drainage of pericardial fluid without the potential complications associated with repeated needle sticks from a pericardiocentesis. This procedure can “buy time” if an operating room and/or a Surgeon is not immediately available to perform a pericardial window.

The technique is similar to that of placing an indwelling central venous line. Clean and prepare the patient. Insert the spinal needle, blindly or with ECG monitoring, as described in the previous sections (Figure 36-7). Aspirate to confirm that the tip of the spinal needle is within the pericardial cavity (Figure 36-9A). It is imperative that the tip of the spinal needle be within the pericardial cavity and not within the cardiac chamber. If intracardiac placement of the needle is suspected, the position of the needle must be verified by one of the methods described in the section on “Blind insertion technique,” by fluoroscopy, or using ultrasonography.

Grasp and stabilize the spinal needle with the nondominant hand. Gently remove the syringe from the spinal needle with the dominant hand. Insert the guidewire through the needle and into the pericardial cavity (Figure 36-9B). Advance the guidewire until approximately one-third of its length is within the patient. Stabilize the guidewire with the nondominant hand. Remove the needle over the guidewire while leaving the guidewire within the pericardial cavity (Figure 36-9C).

Stabilize the guidewire with the nondominant hand. Advance the dilator over the guidewire and into the pericardial cavity (Figure 36-9D). If the guidewire is within the heart, dilating a tract through the myocardium can result in cardiac tamponade and/or exsanguination. It is therefore imperative to know that the guidewire is within the pericardial cavity and not within the heart. Remove the dilator while leaving the guidewire within the pericardial cavity. Advance the soft multihole catheter over the guidewire and into the pericardial cavity (Figure 36-9E). Remove the guidewire while leaving the catheter within the pericardial cavity (Figure 36-9F). Secure the catheter at the skin with the nondominant hand. Attach a syringe to the catheter and aspirate pericardial fluid. This should cause a rapid improvement in the patient's clinical status. Detach the syringe and attach a three-way stopcock to the catheter.20 Secure the catheter to the skin with nylon sutures.

Ultrasound-Guided Technique

Many authors feel that ultrasound-guided pericardiocentesis is now the standard of care.14,20,37,38,44 The heart is best scanned with the patient in the semierect or left lateral position if no contraindications exist. Use the 3.5 to 5.0 MHz phased-array or curvilinear ultrasound probe. Examine the heart and pericardial space in 2D and Doppler mode to determine the extent of the pericardial effusion and the area with the largest pericardial effusion.39,40 This is usually around the apex of the heart. There are established ultrasonographic findings that help to distinguish a pericardial effusion from a cardiac tamponade (Table 36-3).35

View the heart and pericardial space using the three standard cardiac ultrasound views. These are the subxiphoid or subcostal view, the parasternal long axis view, and the apical four-chamber view. Refer to Chapter 29 for a more complete discussion on cardiac ultrasonography. Pericardial fluid is anechoic, appears black on ultrasound, and will collect in a dependent location. Thus, small pericardial effusions will be first seen in the posterior pericardium. Large pericardial effusions appear circumferential, extending around the heart.

The decision to use a parasternal (Figure 36-10) or an apical (Figure 36-11) window depends on which ultrasound views of the pericardial effusion and heart are able to be obtained. The ideal site is where the pericardial effusion is most superficial, has a large stripe or thickness, and where no other structures (e.g., lung or liver) are in the path from the skin to the heart.33,41 The subxiphoid window (Figures 36-12 & 36-13) is not recommended for ultrasound-guided pericardiocentesis. This view commonly includes the left lobe of the liver in the anterior portion of the ultrasound image. Under these conditions, the needle might puncture the liver on the way into the pericardial cavity.

Ultrasonographic features that suggest cardiac tamponade are noted in Table 36-3. This includes right ventricular diastolic collapse (Figure 36-14), right atrial systolic collapse, large pericardial effusion, and dilatation of the IVC. Evaluate the IVC. Place the ultrasound probe in the subxiphoid region, with the probe marker pointing toward the patient's head. The IVC runs parallel with and to the right of the aorta. Use M-mode to measure the diameter of the IVC. The normal IVC ranges from 1.5 to 2.5 cm in diameter and displays respiratory variation. In cardiac tamponade, the IVC is dilated, measuring >2.5 cm in diameter, and does not display respiratory variation.

Position the patient. Determine the location to perform the pericardiocentesis. Clean, prep, and drape the patient as described previously. Apply a sterile probe cover over the ultrasound probe. Apply sterile ultrasound gel over the prove cover. Reidentify and confirm the proper ultrasound probe position.41 This is usually the point where the pericardial effusion is closest to the chest wall.39,40 Insert the spinal needle under ultrasound guidance into the chest wall (Figure 36-15). Insert the needle over the superior border of the rib to avoid the neurovascular intercostal bundle under the inferior edge of the rib. Aspirate as the needle tip is carefully advanced under direct ultrasound visualization into the pericardial space (Figure 36-16).

If there is any question as to whether the needle tip is in the pericardial space, or if bloody fluid is aspirated, use agitated saline to confirm proper needle placement.39–42,46 This requires two 5 mL syringes, one filled with sterile saline and the other filled with air. Attach the syringes to a three-way stopcock. Rapidly move the sterile saline back and forth through the two syringes, creating an aerated saline solution. Rapidly inject the aerated solution through the spinal needle. The identification of hyperechoic “bubbles” on the ultrasound image confirms the location of the needle. An alternative to this technique is to use color Doppler to localize the needle tip.45

Subxiphoid Pericardial Window

A pericardial window will minimize false-negative results seen with a pericardiocentesis, iatrogenic bleeding, and cardiac tamponade from myocardial injury by the pericardiocentesis needle. Prepare the patient as previously described. Inject local anesthetic solution subcutaneously from the xiphoid process across the confluence of the lower ribs and 6 cm down the midline (Figure 36-17A). Inject local anesthetic solution into the muscular layers in the midline over the xiphoid process and continue approximately 8 cm inferiorly.

Make a midline longitudinal incision from the xiphisternal junction to about 8 cm below the tip of the xiphoid process (Figure 36-17A). Incise down to the linea alba. Bluntly dissect the space behind the xiphoid and lower sternum to separate the anterior diaphragm from the sternum. Lift the lower sternum with a retractor (Figure 36-17B). Use an electrocautery unit, if available, for hemostasis. Bluntly divide the fatty tissue and retrosternal attachments of the diaphragm to reveal the pericardium beneath the angle of the xiphoid and the left costal margin.47 It will often appear blue in color due to underlying blood.

Grasp the pericardium with a forceps. Incise the pericardium with a scissors or with shallow strokes of a scalpel (Figure 36-17B). Fluid should rush out rapidly. Remove a piece of the pericardium to make sure that it remains open. Gently explore the pericardial space digitally and with the suction catheter to remove any clot and fluid. Allow the skin to stay open to permit free drainage of the pericardial space. Alternatively, place a 28 French chest tube in the pericardial space and secure it with a purse-string suture through the pericardium (Figure 36-17C). The chest tube may exit the skin incision or a separate incision in the skin. Attach the chest tube to a suction source. Close the linea alba with interrupted 2-0 Vicryl sutures. Close the subcutaneous tissue and skin with 3-0 nylon sutures.

Catheter‐over‐the-Needle Technique

A long catheter-over-the-needle mounted on a syringe may be used, if available, instead of a spinal needle mounted on a syringe. Use a 16 to 18 gauge, 7.5 cm or longer catheter-over-the-needle for older children, adolescents, and adults. Use an 18 to 20 gauge, 3.75 cm catheter-over-the-needle for infants and small children. The procedure is the same as using a spinal needle up to the point of the needle entering the pericardial space. Stop advancing the catheter-over-the-needle once the pericardial space is entered. Securely hold the syringe so it does not move inward or pull outward. Advance the catheter over the needle and into the pericardial cavity. Continue to advance the catheter until its hub is against the skin. Securely hold the catheter hub against the skin. Remove the syringe and needle as a unit. Attach a 20 mL syringe to the catheter hub and aspirate. The remainder of the procedure is as described previously.

Alternative Approaches

The subxiphoid approach is the classic or traditional approach, and has been described previously. The use of bedside ultrasonography is changing the technique to a more apical approach.31,42 This area tends to be closer to the anterior chest wall and where the pericardial effusion is the largest; both of which make the procedure easier to perform under ultrasound guidance.

The blind technique can also be performed using the parasternal, intercostal, or periapical approaches. It was previously recommended to insert the needle perpendicular to the skin and 3 to 4 cm lateral to the sternum for the parasternal approach to avoid the internal mammary artery. Needle insertion just lateral to the sternal border will also avoid the internal mammary artery.48 The intercostal approach should not be blindly used as it increases the risk of lung penetration by the needle and a subsequent pneumothorax. A blind apical approach is also not recommended. The lingula of the left lung and the pleural space are close to this site. A needle can puncture the lung or aspirate a pleural effusion.

It must be emphasized that the lack of blood return does not rule out the diagnosis of cardiac tamponade. False-negative aspirations from a pericardiocentesis are well documented and are described at rates as high as 80%.36 The occurrence of false-negative aspirations is often due to clotted blood in the pericardial space that cannot be aspirated or from failure to enter the pericardial space.

A dramatic improvement in the patient's clinical status should be observed after the successful drainage of the pericardial space. This is true even if only a small volume of 15 to 20 mL is drained. The patient's blood pressure and cardiac output should increase while intracardiac pressure and intrapericardial pressure decrease. Obtain a chest radiograph after the procedure to rule out a hemothorax and/or pneumothorax. Obtain an ECG to look for changes consistent with coronary artery injury from the needle.

A pericardiocentesis is often performed in the nontraumatic medical patient. In these cases, send the pericardial fluid for chemical, cytologic, and microbial analyses to determine the etiology of the pericardial effusion. Routine laboratory analysis should include the appearance of the fluid, a cell count and differential, glucose level, lactate dehydrogenase (LDH) level, pH, and total protein level. Cytology may reveal a malignant etiology of the effusion. The microbiology lab should perform a gram stain, acid-fast stain, aerobic and anaerobic bacteria cultures, fungal cultures, and viral cultures.

Secure the catheter with sutures to the skin and check for stability. If not already done, consult a Surgeon for definitive care of trauma patients. Prepare these patients for rapid transport to the Operating Room. Monitor patients for reaccumulation of pericardial fluid and for hemodynamic instability. If fluid reaccumulates, the procedure should be repeated or the stopcock opened (if placed) and the pericardial space reaspirated. Flush with sterile saline after each aspiration to maintain the patency of the catheter. Consult a Thoracic Surgeon if purulent fluid is aspirated in medical patients. All patients must be admitted to an intensive care unit for further monitoring, evaluation, and treatment.

Complication rates vary from 4% to 40%.14,43 The complication rates of ultrasound-guided aspirations have been reported to be less than 5%.14 Death may result from recurrence or occurrence of tamponade, bleeding, or dysrhythmias. Few if any deaths have been reported with ultrasound-guided aspirations. Reaccumulation of pericardial fluid may occur in up to 70% of blind aspirations.14 Continuous drainage with a pericardial catheter can reduce this to 25%.14 Bleeding, hemothorax, and/or cardiac tamponade can occur due to injury of the myocardium, coronary arteries, pericardial vasculature, or internal mammary vessels by the spinal needle. To minimize injury, do not rock the spinal needle or change its direction once it is inserted into the patient. A pneumothorax or pneumopericardium can form from penetration of the lung by the spinal needle. Dysrhythmias, ventricular fibrillation, ventricular tachycardia, or asystole can occur if the needle penetrates the myocardium. Hepatic damage leading to leakage of bile or blood can be seen if the needle penetrates the liver. If the patient is awake and alert, a vasovagal reaction can occur. False-negative aspirations (i.e., a dry tap) occur if the blood in the pericardial cavity is clotted or if the needle is not within the pericardial cavity. False-positive aspirations may be seen if the needle is within the heart chamber or a vascular structure.

Pericardiocentesis is an infrequently performed procedure. It can be lifesaving when a patient has a pericardial tamponade. The procedure is relatively simple yet has a significant rate of complications, morbidity, and mortality. The use of bedside Emergency Department ultrasonography to assist in making the diagnosis and in guiding the placement of the pericardiocentesis needle dramatically reduces false diagnoses and complications. The exact role of pericardiocentesis in trauma remains controversial, but it may be lifesaving in the unstable patient before they are able to receive definitive surgical therapy.