Emergency pericardiocentesis

INTRODUCTION — Pericardial effusion and cardiac tamponade represent a spectrum of disease with wide variation in clinical presentation [1,2]. While all significant pericardial effusions are of clinical importance, emergency drainage is needed only for patients with hemodynamic compromise. Cardiac tamponade with hemodynamic collapse is an absolute indication for emergency pericardial drainage via pericardiocentesis or surgical pericardiotomy.

The lethality of pericardial effusions has been recognized for centuries. Riolanus suggested sternal trephination to release pericardial fluid in 1653 and the Spanish physician Romero described intercostal surgical drainage in the early 19^th century [3]. The Viennese thoracic surgeon Franz Schuh performed the first successful blind pericardial aspiration in 1840 via a left parasternal approach [4]. Marfan later described the subxiphoid technique in 1911 [5]. Despite significant complications and safety concerns, this remained the standard approach for blind pericardiocentesis through the late 20^th century. Experience with echocardiography-directed pericardiocentesis paralleled technical advances in ultrasound during the 1970s, and has evolved as the procedure of choice due to its improved safety and efficacy [6-9]. Nonetheless, blind subcostal or parasternal pericardiocentesis remains a standard procedure for emergency pericardial drainage when ultrasound guidance is unavailable.

The indications, contraindications, preparation, equipment, and techniques of emergency pericardiocentesis will be reviewed here. Cardiac tamponade and its related diseases and non-emergency pericardiocentesis are discussed separately. (See "Cardiac tamponade" and "Initial evaluation and management of blunt cardiac injury" and "Constrictive pericarditis: Diagnostic evaluation" and "Pericardial disease associated with cancer: Clinical presentation and diagnosis" and "Pericardial effusion: Approach to management", section on 'Indications for pericardial fluid removal'.)

ANATOMY AND PHYSIOLOGY — The parietal pericardium is a fibrous sac that encloses the heart and the roots of the great vessels (figure 1). The cone-shaped sac rests on the diaphragm and fuses superiorly with the adventitia of the great vessels. The pericardium and heart lie between the pleural sacs. The pericardium is fixed within the thorax by attachments to the anterior diaphragm, the sternum, and the fourth and fifth left costal cartilages. The phrenic nerve innervates the pericardium as its runs between the mediastinal pleura and fibrous pericardium.

In health, the pericardium envelops the heart loosely, but is rigid enough to provide stability within the thoracic cavity and to limit cardiac distention (pericardial constraint). The normal pericardial space contains <50 mL of thin serous lubricating fluid that is an ultrafiltrate of plasma. Lymphatic drainage of the pericardium to mediastinal and tracheobronchial lymph nodes provides the anatomic basis for pericardial involvement in the pathology of these regions.

Within the pericardium, the anterior sternocostal surface of the heart is dominated by low pressure right sided chambers while the left cardiac border and apex represent the left ventricle. The right coronary and left anterior descending coronary arteries course over the anterior surface of the heart where they are vulnerable to inadvertent puncture during pericardiocentesis.

Several other important vessels course along the thoracic cage. Intercostal vessels course in their respective neurovascular bundles at the inferior rib margin. Needle insertion over the superior rib margin avoids these structures. The internal thoracic (mammary) artery and vein courses parallel to the sternum 1 to 3 cm from the bony border before dividing into the superior epigastric and musculophrenic vessels at the sixth intercostal space.

When performing the procedure, clinicians should be aware of the vital structures in proximity to the heart. These include the lungs, liver, and diaphragm (figure 2).

Critical cardiac compression can occur with the accumulation of fluid, pus, blood, clot, or gas in the pericardium. The cardiovascular consequences depend upon the amount and speed of accumulation and the patient's physiologic reserve [10]. Cardiac tamponade represents the decompensated phase of cardiac compression [2].

CONTRAINDICATIONS — There is no absolute contraindication to pericardiocentesis in an emergency. However, more definitive treatments should be considered if circumstances allow. Pericardiocentesis is a temporizing measure in acute traumatic hemopericardium and should not delay a more aggressive approach, such as emergency thoracotomy, when indicated. Such delays may increase mortality in traumatic hemopericardium [11]. (See "Initial evaluation and management of penetrating thoracic trauma in adults" and "Cardiac tamponade".)

Several relative contraindications to pericardiocentesis exist. Coagulopathy is an important consideration with any invasive procedure. However, the risk of bleeding may be overestimated and does not preclude emergency lifesaving procedures, such as emergency pericardiocentesis for cardiac tamponade with shock [12]. Anticoagulation and coagulopathy are not associated with significant rates of major bleeding in patients undergoing echo-guided pericardiocentesis by experienced proceduralists [13]. Similarly, thrombocytopenia is not associated with an increase in major bleeding complications [13,14]. Blood product transfusion may be performed to reverse coagulopathy if time allows, but this may not reduce the risk of bleeding [15,16]. The subxiphoid approach may be associated with higher bleeding risk in coagulopathic patients and is often avoided if another approach is feasible.

Pericardiocentesis is relatively contraindicated when the effusion is associated with aortic dissection or myocardial rupture due to the potential risk of aggravating the dissection or rupture via rapid pericardial decompression and restoration of systemic arterial pressure [17,18]. However, such concerns are secondary if an alternative life-saving solution is not immediately available. Controlled small-volume pericardiocentesis to relieve critical tamponade has been reported as a successful bridge to emergency surgery in case series of tamponade associated with aortic dissection [19,20].

MONITORING AND PREPARATION — Monitor all critically ill patients continuously with both pulse oximetry and cardiac tracings. Before pericardiocentesis, provide airway and respiratory support as clinically indicated. Necessary interventions may range from supplemental oxygen to intubation and mechanical ventilation. Beware that a sudden decrease in preload and vasomotor tone, as occurs with rapid sequence intubation and positive-pressure ventilation, can cause acute hemodynamic decompensation, including cardiac arrest, in patients with tamponade physiology [21,22]. Life-support medications should be available during the procedure given the critical nature of the condition and the hemodynamic changes that can occur with successful pericardial puncture and decompression. It may be prudent to obtain emergency surgical consultation in case immediate surgical drainage is needed.

Monitoring the electrocardiograph (ECG) tracing while advancing the pericardiocentesis needle, enables the clinician to detect needle contact with the epicardium, to prevent cardiac puncture. To do this, attach an alligator clip to the base of the pericardiocentesis needle and monitor it via a precordial (V) lead of an ECG machine set to continuous rhythm display. In this configuration, the pericardiocentesis needle acts as an exploring electrode.

Contact of the needle with the epicardium is signaled by immediate ST and PR segment elevation with ventricular and atrial contact, respectively [23,24]. Should this occur, withdraw the needle immediately. ECG monitoring of the needle is not critical, and the practice may be omitted in an emergency, in the absence of essential equipment, or when there is concern for arrhythmias due to incomplete electrical grounding of the exploring electrode [2,25,26]. Ultrasound guidance obviates the need for ECG monitoring.

MATERIALS — A 7 to 9 cm, 18 gauge spinal needle and large volume (60 to 80 mL) syringe are the minimum supplies needed for blind pericardiocentesis. In infants and small children, a 20 gauge spinal needle is recommended and in older children, a 4 cm (1.5 inch) 16 to 18 gauge over the needle catheter may suffice. If the need for pericardiocentesis is anticipated, all equipment necessary to optimize the procedure should be prepared. An equipment list is provided in (table 1).

Insertion of a pericardial drain is always preferred. If time allows, be sure to assemble these additional materials prior to performing the procedure. Preassembled pericardiocentesis sets are commercially available. Alternatively, a number of common six to eight French sterile catheters, including a pigtail catheter, introducer sheath, or single or multi-lumen central venous catheter, may be substituted as a pericardial drain. Prepackaged central venous catheter sets provide most of the supplies needed for emergency pericardiocentesis. Unlike a spinal needle, the thin-walled 18 gauge introducer needle included in pericardiocentesis and central venous access kits accommodate a standard J-tip guidewire for subsequent drain deployment via Seldinger technique.

When using two-dimensional (2D) ultrasonography to guide pericardiocentesis, turn on the machine and allow it to warm up, and then adjust it to the appropriate parameters. The procedure is typically performed with a 2 to 4 megahertz (MHz) probe. A standard curvilinear probe works well for subcostal views but a small footprint curved transducer improves intercostal imaging.

TECHNIQUE OVERVIEW

General preparation — Most patients experiencing hemodynamic collapse from cardiac tamponade are supine. Awake patients may experience dyspnea and orthopnea and require upright or semi-recumbent positioning for comfort [27,28]. Positioning at 30 to 45 degrees increases dependent pooling of pericardial fluid and brings the heart closer to the chest wall. Sedation is rarely required and is not recommended in hemodynamically compromised patients due to the risk of acute decompensation. If sedation is used in awake patients without obvious hemodynamic compromise, short-acting medications (eg, ketamine, fentanyl, midazolam) are preferred.

The optimal approach to pericardial drainage depends upon patient habitus, the distribution of pericardial fluid, and the availability of ultrasound. Ultrasound, or echocardiography, is the most common means of confirming a pericardial effusion and enables safer and more reliable percutaneous drainage compared with a blind approach [29,30]. However, blind pericardial drainage may be necessary for patients with suspected deterioration from cardiac tamponade and when ultrasound is unavailable. A high-quality video demonstrating emergency pericardiocentesis is available in the following reference [31].

Despite the difficulties encountered in emergency circumstances, every effort should be made to use aseptic technique when performing emergency pericardiocentesis.

●Prepare the skin by applying a chlorhexidine-based solution to the chest and upper abdomen and drape the region to maintain sterility during hardware manipulation. Don a sterile gown, gloves, mask, and hat.

●Anesthetize the puncture site and needle track in alert patients via infiltration of local anesthetic (eg, 1 to 2 percent lidocaine). The pericardium is very sensitive and should also be anesthetized.

●Perform pericardiocentesis at the selected site. (See 'Selecting the approach for pericardiocentesis' below.)

Simple needle aspiration provides immediate hemodynamic benefit, but secondary placement of a pericardial drain is recommended to ensure continuous access. The Seldinger guidewire technique is preferred. Access to the pericardial space is gained using a 7 cm, 18 gauge, thin-walled introducer needle or sheathed catheter over needle assembly.

Selecting the approach for pericardiocentesis — Pericardial fluid is not always circumferential or equally distributed within the pericardial sac. Loculation occurs in up to one-third of nontraumatic effusions [32,33]. Also remember that the critical volume sufficient to cause tamponade is much smaller when pericardial fluid has accumulated rapidly [7].

Ultrasound determination of the ideal drainage site and needle trajectory has supplanted estimation based upon palpation and percussion. Systematic ultrasound assessment is performed using several windows (subcostal, parasternal, and apical). Observational studies of pericardial effusion distribution suggest that left chest access points are often superior to the traditional subxiphoid approach [34]. Uncontrolled echocardiography-directed studies confirm successful aspiration from these sites in patients selected using ultrasound guidance [8,29,35-37]. Among potential chest sites, the left parasternal, and apical approaches are most commonly used (figure 3). The parasternal and apical approaches have not been studied in infants or children.

Subcostal (subxiphoid) — The extrapleural subcostal pericardiocentesis approach is performed as follows (figure 4) [2,9,26,38,39]:

●Introduce the needle substernally 1 cm inferior to the left xiphocostal angle. Once beneath the cartilage cage, lower the needle so it approximates a 30-degree inclination with the chest wall [40].

●Aim the needle toward the left mid-clavicle and advance it slowly while continuously aspirating. If no fluid is aspirated, the needle should be withdrawn promptly and redirected. In the absence of ultrasound guidance, withdraw the needle to the skin and redirect it along a deeper slightly posterior trajectory. The required depth of insertion is affected by the patient's anatomy. In most cases, a 7 to 9 cm needle is adequate, but longer needles (up to 12 cm) may be needed for patients with more anterior thoraco-abdominal soft tissue (eg, class 2 or 3 obesity). In infants and small children, 4 cm (1.5 inch) needles are sufficient.

●If no fluid is aspirated on the second attempt, withdraw the needle to the skin and redirect it 10 degrees to the patient's right of the last dry needle aspiration path. Perform systematic redirected aspirations by working from the patient's left to right until the needle is aimed toward the right neck.

Ultrasound guidance generally enables the clinician to avoid inserting the needle into other organs. However, interposition of the left liver lobe is often recognized on subcostal imaging and the lobe may be traversed intentionally during pericardiocentesis, if an alternative site is not available.

Parasternal — The left sternal border is the landmark for a parasternal approach (figure 5). Left parasternal access is most frequently used.

●Insert the needle perpendicular to the skin and over the cephalad border of the fifth or sixth rib immediately adjacent to the sternal margin. The cardiac notch of the left lung exposes the pericardium at this site.

●Avoid puncturing more laterally (greater than 1 cm) to prevent injury to the internal thoracic (mammary) vessels.

An analogous right parasternal approach is occasionally used when ultrasound predicts superior access at this site.

Apical — The apical pericardiocentesis approach reduces the risk of cardiac complications by taking advantage of the proximity to the thick walled left ventricle and the small apical coronary vessels (figure 6). However, proximity to the left pleural space increases the risk for pneumothorax [41].

The apical insertion site is at least 5 cm lateral to the parasternal approach within the fifth, sixth, or seventh intercostal space. Advance the needle over the cephalad border of the rib and towards the patient's right shoulder.

Ultrasound-guided pericardiocentesis technique — In contrast to the high rates of procedure related complications associated with blind aspiration [4,7,42-44], multiple observational studies of ultrasound-guided pericardiocentesis report improved safety, clinician satisfaction, and success (greater than 97 percent) [35,36,45,46]. Ultrasound remains the principal diagnostic test to confirm critical pericardial effusion and is therefore often available to guide aspiration (figure 5 and figure 6). A high-quality video demonstrating emergency pericardiocentesis is available in the following reference [31].

Perform ultrasound-directed pericardiocentesis as follows:

●Prepare the patient and assemble the necessary equipment. (See 'General preparation' above.)

●Using ultrasound, determine the presence and distribution of pericardial fluid. Systematically examine the heart and look for effusions at each imaging window (subcostal, parasternal, apical, and any additional views).

●Select the best entry site. The optimal site contains the largest pericardial fluid accumulation that is closest to the chest wall and can be entered without puncturing any adjacent vital organs. Patient repositioning (eg, reverse Trendelenburg) may redistribute pericardial fluid and affect the target window. Relevant vascular structures to avoid, such as the internal mammary artery, can be identified during this evaluation.

●Select a target fluid layer (distance from pericardium to epicardium) of at least 1 cm to avoid cardiac puncture. Ultrasound does not traverse air so the lung is avoided if the needle trajectory mirrors the approach delineated by ultrasound.

One of three techniques may be employed for ultrasound-guided pericardiocentesis:

●Static imaging uses ultrasound guidance for procedure planning, but does not provide real-time ultrasound imaging during the procedure.

●Remote guidance uses ultrasound to view the heart and effusion during the procedure but rarely provides direct observation of needle penetration.

●Dynamic guidance uses real time ultrasound imagery to view and guide the needle during the approach and pericardial puncture.

There are little controlled data to support any one technique, and the clinician should determine the best approach based on experience and available resources.

Static imaging using pre-procedure ultrasound to assess the puncture site and angle is the traditional method. With static imaging, the skin puncture site and trajectory are outlined with two skin marks. The needle trajectory mirrors the transducer angle during ultrasonography of the target effusion. Note this angle carefully while imaging the effusion. Measure the distance from the skin to the pericardium overlying the target effusion; the distance is typically 2 to 4 cm. Contrast injection and fluid removal may be monitored from a remote transducer position. An observational study of this technique reported successful placement in all 21 patients with no observed complications [47].

For the dynamic approach, orient and insert the needle parallel to the localizing ultrasound beam to obtain an in-plane approach [48]. At the parasternal site, this may require a 45-degree angled medial-to-lateral or lateral-to-medial needle trajectory [49,50]. Real-time ultrasound visualization of needle passage is optimal, but continuous visualization of the needle tip may be difficult. Misinterpretation of the ultrasound image can result in inadvertent needle misdirection outside of the predetermined trajectory. Use of a needle guide affixed to the ultrasound probe helps align the needle for continuous needle visualization [37,51].

Pericardiocentesis technique without ultrasound guidance — When ultrasound is not available, perform emergency pericardiocentesis as follows:

●Prepare the patient and necessary equipment as above. (See 'General preparation' above.)

●Slowly advance the pericardiocentesis needle in the predetermined trajectory with continuous aspiration of the attached syringe. Move the needle along a single in-and-out vector only; side to side movement of the needle tip can lacerate tissue.

●Increased resistance to the needle, followed by a distinct give or pop, suggests penetration of the pericardium [10,26]. Patients may experience acute, sharp pain with penetration. Stop advancing the needle once fluid is freely aspirated.

●Stabilize or attach a surgical clamp to the needle shaft at the skin surface to brace the needle and prevent inadvertent movement during the ensuing steps. A ticking sensation signifies needle contact with the epicardium. If this occurs, withdraw the needle slightly [52].

●If a catheter-over-needle assembly is used for initial access, insert the needle an additional 2 mm after initial fluid aspiration, and advance the catheter over the core needle into the pericardial space [8].

●If drain insertion is intended, aspirate several milliliters to confirm free flowing pericardial fluid, but do not withdraw a large amount of fluid in an attempt to drain the pericardium completely as this may hinder subsequent guidewire deployment.

Intrapericardial needle confirmation — Aspiration of fluid does not always confirm pericardial drainage, as pleural and peritoneal collections may be traversed during pericardiocentesis. Similarly, withdrawal of bloody fluid may represent hemopericardium or accidental cardiac puncture, which can be difficult to discriminate. Hemodynamic improvement following aspiration of bloody fluid is more consistent with pericardial aspiration [53]. Monitoring fluid removal from a remote transducer position can be helpful.

Ultrasound localization of the needle tip may be difficult and bubble contrast injection through the exploring needle is a useful adjunct to confirm needle position [9,49,54-57]. Agitated saline bubble contrast can be prepared by rapidly mixing 9 mL of saline with 1 mL of air between two syringes, connected via a three-way stopcock, immediately before injection. Layering of contrast outside the heart confirms pericardial localization. Rapid contrast washout or intracardiac swirling varies with the patient's cardiac output, but both signify myocardial perforation [58]. Ultrasound visualization of the deployed guidewire within the pericardial space is another confirmatory method.

Drain placement — Pericardial drain insertion provides easy access for serial fluid removal and reduces recurrence and the need for subsequent pericardiocentesis.

●Exchange the needle (or catheter, if a catheter-over-needle assembly was used) for a more robust drain via the Seldinger technique. Following confirmatory aspiration of pericardial fluid, pass a flexible tipped guidewire through the needle into the pericardial sac. Remove the needle while securing the guidewire in place to maintain pericardial access.

●Make a small stab skin incision at the entry site. Dilate the chest wall passage and pericardium with a tissue dilator prior to drain insertion.

●Advance the drain into position over the indwelling guidewire. Estimate or measure the distance to the target pericardial collection and advance the drain such that the proximal drain is just beyond this depth to avoid inserting the drain too deep. Then, withdraw the guidewire. Confirm proper drain placement by aspirating pericardial fluid.

●Secure the drain in place on the chest wall with sutures and place a dry sterile dressing over the site.

Catheter drainage and care — The volume of pericardial fluid required to relieve tamponade varies significantly among patients depending upon their position on the pericardial pressure-volume curve. Once the catheter is in place, aspirate pericardial fluid rapidly using a large syringe (60 to 80 mL) until cardiopulmonary compromise is relieved. Hemodynamic improvement generally occurs after the removal of 200 to 300 mL of fluid. Place a three-way stopcock between the catheter and aspirating syringe to aid in serial aspirations while maintaining sterility.

Limit acute total drainage of large effusions to less than 500 mL to avoid pericardial decompression syndrome [9,59,60]. Keep the catheter connected to a sterile closed drainage system after initial aspiration. Do not use continuous negative high-pressure systems or vacuum containers.

Anticipate pericardial reaccumulation after initial decompression. Avoid continuous drainage because of the high rate of catheter occlusion; intermittent drainage optimizes drain patency. Flush the indwelling catheter with 5 mL of sterile or heparinized saline between aspirations, performed every four to six hours or as clinically indicated [8]. Inadequate initial drainage or reaccumulation despite a functioning drain indicates the need for immediate surgical drainage [61].

Prophylactic antibiotics are not indicated for acute indwelling pericardial drains.

COMPLICATIONS — Large observational studies of non-emergency echocardiography-guided pericardiocentesis report major complication rate of <2 percent [35,36,61,62]. However, delayed clinical decompensation following attempted and successful pericardiocentesis may also reflect procedural complications.

The most serious and immediate mechanical complications of pericardiocentesis are myocardial puncture or laceration, vascular injury (coronary, intercostal, internal mammary, or intraabdominal), pneumothorax, tension pneumopericardium, air embolism, and arrhythmia (ventricular and supraventricular). Myocardial and coronary puncture may be initially silent and present with delayed hemopericardium that is poorly responsive to needle or catheter aspiration.

Purposeful or inadvertent transperitoneal needle passage can traverse intraabdominal organs. The liver is most commonly involved but is associated with low risk of significant hemorrhage. Perforation of a hollow viscus is theoretically possible but rarely reported.

Vasovagal bradycardia response to pericardial decompression occurs in up to 25 percent of patients and may be severe [42,45].

The pericardial decompression syndrome refers to paradoxical cardiopulmonary deterioration following relief of cardiac tamponade [59,60,63-65]. Manifestations may occur following initial clinical improvement and include acute pulmonary edema; acute right, left, or biventricular heart failure; and/or cardiogenic shock unrelated to anatomic injury. Pericardial decompression syndrome occurs in up to 5 percent of cases and is associated with rapid pericardial decompression. As such, the condition may be preventable by limiting immediate pericardial fluid drainage to restore hemodynamics to no more than 500 mL, followed by controlled slower drainage of the remaining effusion [66]. Supportive care is the treatment for pericardial decompression syndrome.

Lastly, pericardiocentesis may fail to relieve tamponade. Loculated effusion and acute hemopericardium are factors associated with unsuccessful catheter drainage [32,35,36,45].

SUMMARY AND RECOMMENDATIONS

●Pathophysiology and indications – Pericardial effusion and cardiac tamponade represent a spectrum of disease with wide variation in clinical presentation. The cardiovascular consequences of pericardial effusion depend upon the amount of fluid, the speed of accumulation, and the patient's physiologic reserve. Emergency drainage is needed only for patients with hemodynamic compromise. Cardiac tamponade with hemodynamic collapse is an absolute indication for immediate pericardial drainage via pericardiocentesis or surgical pericardiotomy. (See "Cardiac tamponade" and 'Anatomy and physiology' above and 'Contraindications' above.)

●Monitoring and preparation – Monitoring is performed with pulse oximetry and standard cardiac monitoring. Monitoring the electrocardiogram tracing while advancing the pericardiocentesis needle can help prevent cardiac puncture, but is not essential, especially when ultrasound guidance is used. Before pericardiocentesis, provide airway and respiratory support as clinically indicated. Beware that a sudden decrease in preload, as occurs with tracheal intubation and positive-pressure ventilation, can cause acute decompensation, including cardiac arrest, in patients with cardiac tamponade. (See 'Monitoring and preparation' above.)

●Equipment – The materials needed to perform emergency pericardiocentesis are described in the text and listed in (table 1). Insertion of a percutaneous pericardial drain via Seldinger technique requires use of a large bore, thin-walled introducer needle to accommodate a guidewire. (See 'Materials' above.)

●Approach and ultrasound guidance – The optimal approach to pericardial drainage depends upon patient habitus, the distribution of pericardial fluid, and the availability of ultrasound. Pericardial fluid is not always circumferential or equally distributed within the pericardial sac. Loculation occurs in up to one-third of nontraumatic effusions. Ultrasound is the most common means of confirming a pericardial effusion and enables safer and more reliable percutaneous drainage compared with a blind approach. However, blind pericardial drainage may be necessary for patients with suspected deterioration from cardiac tamponade and when ultrasound is unavailable. (See 'General preparation' above.)

The performance of both ultrasound-guided and blind emergency pericardiocentesis is described in the text. (See 'Ultrasound-guided pericardiocentesis technique' above and 'Pericardiocentesis technique without ultrasound guidance' above.)

●Site of entry – Observational studies of pericardial collection distribution suggest that several anterior chest access sites are frequently superior to the traditional subxiphoid approach. Ultrasound often demonstrates the left parasternal and apical sites as optimal approaches. (See 'Selecting the approach for pericardiocentesis' above.)

●Drainage – Insertion of a pericardial drain is preferred to simple aspiration. Simple needle aspiration provides immediate hemodynamic benefit, but placement of a pericardial drain is recommended to ensure continuous access. (See 'Drain placement' above.)

Limit immediate effusion drainage to restore hemodynamics to less than 500 mL in large effusions to avoid pericardial decompression syndrome. Avoid continuous drainage because of the high rate of catheter occlusion; intermittent drainage optimizes drain patency. Flush the indwelling catheter with 5 mL of sterile or heparinized saline between aspirations, performed every four to six hours or as clinically indicated. (See 'Catheter drainage and care' above.)