CONTENTS
- Rapid Reference 🚀
- Causes of tamponade
- Symptoms
- Physical exam
- EKG
- Radiology
- Echocardiography
- Diagnosis: Overall approach
- Management
- Finer points:
- Podcast
- Questions & discussion
- Pitfalls
Key tests to consider in evaluation of tamponade are listed below:
pulsus paradoxus >10 mm 📖
- Good sensitivity (but false-negatives occur in hypovolemia, LV failure, aortic regurgitation, or mechanical ventilation).
- Nonspecific (also seen in RV dysfunction, asthma, COPD, severe hypovolemia, extreme obesity).
IVC dilation 📖
- Highly sensitive, but may be absent in low-pressure tamponade.📖
- Nonspecific (also seen in RV failure, volume overload).
right atrial collapse 📖
- Any degree of atrial collapse is reasonably sensitive, but nonspecific.
- If the right atrium is collapsed most of the time, this is more specific for tamponade.
right ventricular diastolic collapse 📖
- Very sensitive, but may be absent in coexisting RV dysfunction (e.g., pulmonary hypertension).
- Very specific, but can also be caused by hypovolemia or large pleural effusion.
- Malignancy (most often: lung, melanoma, breast, lymphoma, leukemia).
- Hemopericardium:
- Post-procedure (e.g., cardiac surgery, atrial fibrillation ablation, pacemaker insertion, percutaneous coronary intervention with coronary artery perforation).
- Trauma.
- Aortic dissection.
- Myocardial free wall rupture (most often following MI).
- Supratherapeutic anticoagulation plus another cause of effusion (e.g., uremia).
- Idiopathic pericarditis.
- Uremia.
- Autoimmune:
- Lupus.
- Rheumatoid arthritis.
- Mixed connective tissue disease.
- Post-myocardial infarction pericarditis.
- Radiation-induced pericarditis.
- Hypothyroidism.
- Infection (e.g., bacteria, tuberculosis, EBV, CMV, HIV). (28087158, 29137910)
Symptoms will vary depending on the underlying etiology of tamponade. Some commonly encountered symptoms include the following:
- Dyspnea (66-90%).
- Dyspnea is the most sensitive symptom.
- Chest pain (12-74%).
- Fever (7-70%).
- Abdominal pain (12-61%).
- Orthopnea (23-51%).
- Syncope (3-6%).
- Palpitations (3%). (Numbers from 35696801)
vital signs
- Tachycardia is generally seen (~75% sensitive).
- Tachypnea is generally seen (~80% sensitive)
- Blood pressure can be anything:
- Hypotension occurs in the later stages of tamponade – and if present this is a very concerning finding.
- Hypertension can occur early on, due to a compensatory sympathetic response. If antihypertensives are given to “control” the hypertension, this may be catastrophic.
other physical exam findings which may be noted
- Jugular venous distension (JVD).
- Pulsus paradoxus is the most useful of the traditional physical examination findings. 📖
- Kussmaul's sign.📖
- Eventually, tamponade may progress to frank cardiogenic shock (e.g., cool extremities, oliguria, altered mental status).
definition
- The pulsus is the decrease in systolic blood pressure during inspiration (black arrow in figure below).
- Normally the pulsus is below ~10 mm. During inspiration, increased venous inflow to the right ventricle causes an increase in right ventricle size that stimulates a reciprocal compression of the left ventricle (secondary to pericardial restraint), leading to reduced cardiac output.
- In tamponade, the pulsus is generally >10 mm. However, there is some disagreement about the optimal cutoff value. For patients with severe hypotension, a lower cutoff value will have superior sensitivity. Alternatively, for patients with normotension, a higher cutoff value (e.g., >15 mm) will have greater specificity.
- Pulsus may be useful in a patient with known pericardial effusion, when you're trying to determine whether tamponade is present. This correlates with respirophasic variation in echocardiographic flow velocities.
three methods to measure the pulsus paradoxus
- (1) Examine the arterial line tracing over several respiratory cycles.
- This is the most accurate way to measure the pulsus.
- Decreasing the sweep speed on the monitor allows for observing the blood pressure during several respiratory cycles.
- The obvious drawback is that this requires placement of an arterial line.
- (2) Auscultation with a manual blood pressure cuff
- Inflate the cuff pressure above the systolic blood pressure, then deflate the cuff extremely slowly.
- When you hear the first Korotkoff sound you are at a pressure corresponding to the upper red line in the above figure.
- Subsequently, you will hear Korotkoff sounds only intermittently (during expiration). At this point you are between the two red lines.
- Eventually, you will hear Korotkoff sounds throughout all phases of respiration. At that point you have reached the lower red line.
- (3) Manual palpation – In severe tamponade the pulsus may approach 30 mm, which may be palpable. (29025544) Indeed, the initial description of pulsus paradoxus in 1873 was based upon the disappearance of any palpable pulse during inspiration. (12057571)
sensitivity
- An elevated pulsus is reasonably sensitive, with sources quoting sensitivity rates of 75-98%. (30037442)
- However, there are several causes of a falsely normal pulsus despite the presence of tamponade:(29025544)
- Severe hypotension (blood pressures are too low to generate an absolute >10 mm differential).
- Marked elevation in LV filling pressures (e.g., severe left ventricular dysfunction).
- Severe aortic regurgitation.
- Any cause of impaired right ventricular filling (e.g., right ventricular hypertrophy).
- Large atrial septal defect.
- Mechanical ventilation (especially with low tidal volumes). (28087158)
- Low-pressure tamponade.
- Arrhythmias.
specificity – other causes of elevated pulsus include:
- Right ventricular dilation (e.g., pulmonary embolism, chronic pulmonary hypertension).
- Constrictive pericarditis, restrictive cardiomyopathy.
- Wide swings in intrathoracic pressure:
- Obstructive lung disease (asthma, COPD).
- Marked dyspnea of any etiology.
- Mechanical ventilation with large tidal volumes.
- Tension pneumothorax.
- Severe hypovolemia. (23891285)
- Extreme obesity. (28087158)
preterminal inspiratory-dependent cardiac output (PIDCO)
- In the most extreme case of tamponade, cardiac output and blood pressure may drop to close to zero – except for when the patient is inhaling. Blood flow occurs only during inspiration (because inspiration is needed to reduce the pressure in the right heart, allowing for venous return). (29025544)
- This may resemble pulsus paradoxus, but it's not the same thing:
- In pulsus paradoxus, blood flow decreases during inspiration.
- In preterminal inspiratory-dependent cardiac output (PIDCO), blood flow increases during inspiration.
- If encountered, this represents an extremely precarious situation, wherein the cardiac output is being maintained solely by negative-pressure inspiration. Cardiopulmonary arrest may occur if the patient stops breathing, or if the patient is intubated. Immediate pericardial drainage is mandatory.
definition
- Normally, jugular venous pressure (JVP) decreases during inspiration (due to negative intrathoracic pressure causing an increase in venous return).
- Kussmaul's sign refers to a paradoxical increase in JVP during inspiration (video below).
- Ultrasonographic Kussmaul's sign: A linear ultrasound probe is placed very lightly over the jugular vein in a transverse orientation (without exerting any pressure on the vein). The probe should ideally be placed near the apex of the jugular vein distension (in a location where significant collapsibility occurs with respiration). Ultrasonographic Kussmaul's sign is present if the cross-sectional area of the jugular vein is seen to enlarge during inspiration.
physiological basis of Kussmaul's sign
- During inspiration, downward diaphragmatic excursion compresses the abdominal contents. This increases return of venous blood from the abdomen into the thorax.
- If the right ventricle is unable to accommodate this influx of blood, then increased blood entry into the chest will cause intrathoracic venous congestion which, in turn, increases the jugular vein pressure. Thus, the pathophysiological basis of Kussmaul's sign is a right ventricle which is unable to dilate and accept increased preload.
- Kussmaul's sign is thus an internal version of testing for hepatojugular reflux (a test wherein the examiner compressed the liver, to determine whether increased venous return from the abdomen would increase the jugular venous pressure).
causes of Kussmaul's sign
- Constrictive pericarditis or restrictive cardiomyopathy.
- Pericardial tamponade.
- Right ventricular failure (either acute or chronic), for example:
- Right ventricular myocardial infarction.
- Pulmonary embolism.
- Tricuspid valve stenosis.
clinical utilization of Kussmaul's sign
- (1) Diagnostic value: If noticed, this sign should direct investigation towards causes of right ventricular dysfunction (as listed above).
- (2) Therapeutic value: Kussmaul's sign reflects an inability of the right ventricle to handle additional preload (analogous to an endogenous fluid challenge). This might theoretically imply that additional volume administration will not be beneficial. (29137910)
- EKG is neither sensitive nor specific for tamponade. Findings which may be encountered include:
- Low voltage – seen more often.
- Electrical alternans (varying QRS amplitude from beat to beat) – rarely encountered.
- If these EKG features are seen, a bedside echocardiogram should be performed without delay.
- These EKG findings are caused by large effusions. Given that the patient is still alive, such effusions must be either subacute or chronic. In acute tamponade (e.g., due to post-procedure hemopericardium), the only EKG finding which can possibly occur is tachycardia.
chest radiograph
- A large pericardial effusion may be suggested by an enlarged and globular heart.
CT scan 🌊
- Chest CT scan is highly sensitive for a pericardial effusion. This may also be noticed on CT scans of the abdomen that include the apex of the heart.
- CT scan should not be obtained with the intention of evaluating for tamponade (but rather, echocardiography is utilized for that). However, you may find effusions when obtaining a CT scan to evaluate for other pathology.
- CT scan may reveal the presence of posterior loculated effusion or clot, which may not be visible via transthoracic echocardiography (e.g., following cardiothoracic surgery). However, in most scenarios, transesophageal echocardiography may be the diagnostic test of choice to evaluate for postoperative loculated effusion.
three cornerstone findings
pericardial effusion
- Size doesn't necessarily correlate with the presence of tamponade:
- Rapid development of a small effusion may cause tamponade.
- Gradual development of a large effusion may not cause tamponade.
- Size does relate to the safety and ease of draining the effusion.
- Size is estimated based on thickness in diastole:
- Postoperative patients may have a focal clot in the pericardium that may be difficult to diagnose. Especially in patients status post cardiothoracic surgery, transesophageal echocardiography may be necessary to evaluate for a posterior loculated effusion/clot.
dilated inferior vena cava (IVC)
- IVC dilation is ~95% sensitive for tamponade. (30471929) However, a small or normal IVC size could occur in the context of low-pressure tamponade (which represents a hybrid of hypovolemia and mild tamponade). 📖
- A dilated inferior vena cava is not specific for tamponade, as this is commonly encountered in a variety of other conditions (e.g., volume overload, right ventricular dysfunction, positive pressure mechanical ventilation).
right ventricular (RV) diastolic collapse
- RV diastolic collapse is the hallmark echocardiographic finding of tamponade. The best views to see this are the parasternal long-axis view or any four-chamber view (either apical or subcostal).
- Initially, RV diastolic collapse may be most noticeable in the right ventricular outflow tract and during expiration.
- It's essential to sort out right ventricular diastolic collapse (which is pathological) versus right ventricular systolic collapse (which is normal). There are two ways to do this:
- (#1) Capture a video and then review it in slow motion. If the right ventricle collapses when the mitral valve opens, there is diastolic collapse. If you're not sure how to record video loops and watch them in slow motion using an ultrasound machine, this can easily be done using a smartphone instead (figure above).
- (#2) Apply M-mode in a parasternal long axis, with the M-mode beam cutting through the mitral valve and the right ventricular outflow tract. In tamponade, the right ventricular outflow tract will be compressed when the mitral valve opens (during diastole; figure below).
- Sensitivity of RV diastolic collapse is high (perhaps ~75%), but this may be absent if there are other pathologies which increase right-sided pressures (e.g., pulmonary hypertension, right ventricular myocardial infarction, tricuspid regurgitation). In this situation, collapse of the left atrium may become a useful diagnostic sign. (28087158)
- Specificity of RV diastolic collapse is high, but this may also be seen in hypovolemia (i.e., low-pressure tamponade 📖) or in patients with a large left pleural effusion. (28087158) If either of these conditions is present, it should be treated immediately (e.g., with volume loading or drainage of the pleural effusion). If right ventricular diastolic collapse persists, that is more indicative of tamponade.
other echocardiographic findings
right atrial collapse
- The right atrium is the first chamber to experience collapse (developing prior to right ventricular diastolic collapse).
- This is best seen in the apical four-chamber view or the or subcostal four-chamber view.
- Collapse of the right atrium is sensitive, but not specific for tamponade. Transient buckling of the right atrium is often seen in patients without tamponade. Collapse which persists for more than a third of the cardiac cycle is more specific for tamponade (but pragmatically speaking, this precise distinction lies beyond the scope of critical care POCUS).
- From a pragmatic standpoint:
- Absence of any diastolic collapse of the right atrium would argue against the presence of tamponade.
- If the right atrium is collapsed most of the time, this supports the diagnosis of tamponade.
Doppler variation in blood flow across cardiac valves (echocardiographic pulsus paradoxus)
- Exaggerated respirophasic variation in blood flow across cardiac valves supports a diagnosis of tamponade. This is the echocardiographic equivalent of a pulsus paradoxus.📖
- Tamponade will cause increased respirophasic variation across all the cardiac valves. Cutoff values for the normal degree of flow variation varies between valves:
- Mitral flow normally varies <30%.
- Tricuspid flow normally varies <60%. (35696801)
- It may be difficult to measure Doppler flows accurately and reproducibly. This is especially challenging in patients with limited apical windows, or patients who are tachypneic.
- Echocardiographic pulsus paradoxus is less sensitive and less specific for tamponade than chamber collapse. (29025544) The causes of false-positive or false-negative results are essentially the same as for pulsus paradoxus.📖
the continuum of tamponade
- Tamponade is often referred to as a binary dichotomy (present/absent), but in reality there is a gradual continuum of severity. (29025544) Stages of progressively worsening tamponade may be roughly conceptualized as the following:
- (#1) Abnormal fluctuations in respirophasic blood flow across cardiac valves (echocardiographic pulsus paradoxus).
- This is a very sensitive finding, which may occur before changes in cardiac output or right atrial chamber collapse.
- If this is detected as an isolated finding, the patient often won't have clinical signs of tamponade. However, these patients are at risk of deteriorating into clinically significant tamponade.
- (#2) Pathological collapse of right-sided chambers:
- Cardiac output may start to decrease.
- Blood pressure is often initially maintained due to an endogenous vasopressor response. Narrow pulse pressure (<25% SBP) may be an early sign of reduced cardiac output.
- (#3) Hypotension and shock:
- Hypotension is often a relatively late finding in tamponade.
- Organ hypoperfusion is a very late finding (e.g., poor mental status, renal failure).
diagnostic maneuvers if the diagnosis is debatable
- The presence or absence of tamponade is frequently subject to vigorous debate. Depending on the clinical context, some ways to clarify the diagnosis may include:
- (#1) STAT formal echocardiogram
- This is an option if echocardiography is readily available and the patient is clinically stable. Alternatively, for patients who are clinically unstable, drainage of the pericardium should not be delayed to obtain a formal echocardiogram.
- 🛑 Beware that patients with borderline tamponade can deteriorate rapidly. The patient may not be in tamponade at the time of the echocardiogram, but they may subsequently deteriorate and transition into tamponade later on. So a “negative” echocardiogram performed several hours previously doesn't provide reassurance that the patient is not currently in tamponade.
- (#2) Arterial line placement for continuous monitoring of pulsus paradoxus.
- This is a safe, fast procedure which is readily available.
- An arterial line may be useful to allow for continuous monitoring of a patient who is in borderline tamponade. This could potentially allow for early detection of a deterioration into frank tamponade. However, limitations of the pulsus must be borne in mind (including several causes of false-negative values). 📖
- (#3) Diagnostic & therapeutic pericardiocentesis
- This is the gold standard diagnostic test: Drain the effusion and determine if there is clinical improvement. If the patient improves, then tamponade is diagnosed. If the patient doesn't improve, then tamponade is excluded and additional evaluation is needed for an alternative cause of hemodynamic instability. Even if drainage doesn't improve the patient, this procedure may be helpful by allowing clinicians to confidently move past their concern regarding tamponade – cognitively freeing them to search for alternative diagnoses.
- For patients who are shocked and deteriorating with probable tamponade, drainage should not be delayed pending proof of tamponade. Drainage is the diagnostic test of choice in this scenario.
Venous Inflow = (CVP) – (RA pressure)
RA pressure ~ Pericardial pressure
Venous Inflow ~ [(CVP) – (Pericardial pressure)]
general concept
- Low-pressure tamponade is essentially a shock state due to a combination of hypovolemia and elevated pericardial pressure. The crux of cardiac failure in tamponade is a reduction in cardiac filling due to a decrease in the pressure gradient between the central venous pressure and the pericardial pressure (equations above). Low pressure tamponade reflects a combination of low central venous pressure (CVP) and elevated pericardial pressure – both of which contribute to impaired venous inflow into the heart.
- Patients who gradually develop a pericardial effusion will tend to compensate by retaining volume – so their CVP will increase and they will never develop low pressure tamponade. Low pressure tamponade may occur in the following situations:
- (1) Rapid accumulation of a pericardial effusion (e.g., acute hemorrhagic pericardial effusion).
- (2) Subacute pericardial effusion plus acute volume loss (e.g., hemorrhage, gastroenteritis, or fluid removal at dialysis).
diagnosis of low pressure tamponade
- The diagnosis of low pressure tamponade is generally similar to that of other patients with tamponade, but with a few salient differences:
- (1) The central venous pressure will not be elevated (e.g., the inferior vena cava won't be dilated).
- (2) Pulsus paradoxus may be absent.📖
- (3) There may be a clinical precipitant cause of volume loss (e.g., gastrointestinal hemorrhage, gastroenteritis, diuresis, or dialysis).
management of low pressure tamponade
- The first step is volume resuscitation (e.g., crystalloid or blood – depending on the context). This may have one of two general consequences:
- (#1) The patient stabilizes, and no longer has any significant tamponade. Such patients remain at risk for subsequently developing tamponade, but they don't represent an immediate emergency.
- (#2) The central filling pressures increase, but this doesn't cause clinical improvement. At this point, the patient has transitioned to a typical state of tamponade (aka, “high-pressure tamponade”).
The key management of tamponade is drainage of the effusion – and that should be the priority. However, in some situations it may not be possible to immediately drain the pericardium. While awaiting definitive therapy, the following interventions may be useful:
fluid loading
- Patients who are volume depleted are particularly susceptible to tamponade (“low-pressure tamponade”). Such patients can be stabilized by fluid administration.📖
- Most patients with tamponade will initially respond favorably to fluid administration. However, excess fluid may over-distend the right side of the heart, thereby compressing the left ventricle and impairing cardiac output. Thus, fluid administration should be carefully monitored and discontinued if it appears that additional fluid is not helping.
- Kussmaul's sign reflects that the right ventricle is unable to accept additional fluid, theoretically suggesting that additional fluid loading is unhelpful.📖
vasopressor support (e.g., norepinephrine)
- Pressors may be used as a bridge to pericardiocentesis.
accelerate the heart rate if necessary
- Tamponade creates a limitation on diastolic filling and stroke volume. This causes the cardiac output to become strongly dependent on heart rate (remember that cardiac output equals the heart rate multiplied by the stroke volume).
- Most patients will naturally develop a compensatory tachycardia. However, tachycardia may be absent in patients on negative chronotropes (e.g., beta-blockers) or in patients with conduction system disease.
- If the patient's heart rate is inappropriately normal or bradycardic, use of an inotrope to accelerate the heart rate may be beneficial. (29137910) Epinephrine may be a reasonable choice to accelerate heart rate, without causing systemic vasodilation.
reduce intrapericardial pressure
- Some adjunctive interventions may indirectly reduce the pericardial pressure: (29137910)
- Drainage of a large pleural effusion.
- Reduction of intra-abdominal pressure.
- Avoiding excessively high PEEP (among intubated patients).
anticoagulation reversal
- Potential benefits:
- (1) Anticoagulation reversal may increase the safety of pericardiocentesis.
- (2) For patients with hemopericardium, anticoagulation reversal may be especially critical.
- More on anticoagulation reversal here.📖
avoid intubation if possible
- The combination of positive-pressure ventilation and sedation may cause hemodynamic collapse within the context of tamponade.
- If the patient requires intubation for some other reason, it's generally preferable to drain the pericardium before intubation.
Ideally, drainage will typically be performed by cardiology (usually with placement of a pericardial drain) or cardiothoracic surgery (with creation of a pericardial window in some patients). However, patients in shock who cannot immediately receive these procedures will require emergent drainage. This section discusses emergent pericardiocentesis, with the caveat that this isn't the ideal procedure for most patients.
contraindication to pericardiocentesis
- There are no absolute contraindications to pericardiocentesis in a patient with no other immediate treatment options who is in progressive shock.
- If the ultrasound shows only clotted blood within the pericardium, this generally isn't amenable to needle drainage – either cardiothoracic surgery or thoracotomy may be needed.
- Coagulopathy may be a relative contraindication. However, in a large case series from the Mayo clinic, neither elevated INR nor thrombocytopenia correlated with increased risk of bleeding. (31959530)
- Hemopericardium due to myocardial wall rupture or aortic dissection is a relative contraindication, as this is ideally repaired in the operating room. However, if immediate surgery isn't possible and the patient is actively dying, a pericardial drain should be attempted as a bridge to surgical intervention.
kit
- Various options include the following. (30037442, 27826210) In emergent situations, it may be preferable to use a kit that you're used to.
- (1) Drain insertion using a central line or pigtail catheter kit.
- Insertion of a drain may be preferable in a situation where rapid reaccumulation is possible (e.g., post-procedure hemopericardium, or a patient with coagulopathy).
- (2) Therapeutic drainage only (without placement of a drain) using a long angiocatheter. The angiocatheter may be connected to a three-way stopcock and tubing, to allow for ongoing removal of fluid from the effusion.
positioning & optimal location
- Elevating the head of the bed may cause fluid to shift into a more anterior distribution, facilitating pericardiocentesis from a parasternal or apical approach.
- Different patients may accumulate the deepest pockets of fluid in variable locations.
- Parasternal or apical approaches (through the chest wall) may allow fluid to be reached more easily.
- If a parasternal approach is taken, avoid the internal mammary artery, which often runs vertically a few centimeters lateral to the sternum. Ideally, the internal mammary artery may be identified using Doppler ultrasonography with a linear probe and specifically avoided.
- The subxiphoid approach may generally be less desirable, for the following reasons:(32572594)
- (1) The needle needs to traverse a longer distance (especially in obese patients). This may make it impossible to reach the effusion using the finder needle from a central line or pigtail catheter kit. A lumbar puncture (LP) needle may be needed to remove fluid from the subxiphoid position (but this generally doesn't allow passage of a guidewire through it).
- (2) A subxiphoid approach introduces a risk of liver laceration causing hemoperitoneum.
needle insertion & location confirmation
- The needle should be inserted just above a rib in order to avoid the neurovascular bundle (similar to a thoracentesis).
- Needle insertion should ideally be performed with direct visualization (using an in-plane approach). Continuous negative pressure should be used to aspirate fluid as soon as the needle punctures the pericardium. The tip of the needle should ideally be seen entering the pericardial space.
- If amber fluid returns, then fluid may be therapeutically aspirated (or a wire & catheter may be inserted).
- If bloody fluid returns, there may be some confusion regarding whether the needle is in the pericardium or the ventricle. This can be rapidly sorted out by injecting agitated saline with ultrasound guidance. Ideally the bubbles will show up within the pericardium, confirming intrapericardial location.
How to Perform a Pericardiocentesis_A Parasternal Approach from Cameron Kyle-Sidell
basic labs to consider in pericardial fluid analysis
- Cell count and differential.
- Glucose.
- Protein.
- LDH.
- Cytology.
- Gram stain and culture for bacteria.
- Acid-fast bacillus smear & culture (if TB possible).
CT-guided pericardiocentesis
- The location of pericardial fluid is variable. In some cases, fluid may accumulate in unusual locations that make bedside drainage challenging.
- Depending on patient anatomy, pericardial drainage may be optimally achieved by interventional radiology with CT guidance.
cardiothoracic surgery
- Indications for cardiothoracic surgery may include the following:
- Type A aortic dissection.
- Myocardial free wall rupture (usually following myocardial infarction).
- Recent chest trauma.
- Recent cardiothoracic surgery with pericardial clot.
- Failure or inability to achieve nonoperative drainage.
- Chest compressions alone are likely to be futile in this situation.
- The only pathways to survival include:
- (1) Immediate pericardiocentesis.
- (2) Immediate thoracotomy.
- Available resources and clinical context may dictate the optimal approach. Although counterintuitive, drainage of the pericardium should probably be prioritized ahead of chest compressions.
There is no single gold-standard test or diagnostic criteria to determine the presence or absence of tamponade (indeed, tamponade actually exists on a spectrum, rather than as a single dichotomous variable!). Perhaps the closest thing to a gold standard would be clinical improvement after therapeutic drainage. For obvious reasons, this gold standard cannot be applied to most studies of tamponade.
Therefore, it's largely impossible to obtain any accurate numbers regarding the sensitivity and specificity of any test for tamponade. This chapter does provide some numbers quoted in the literature, but these only provide a rough concept of the performance of various tests. Given varying patient populations and varying clinical definitions used in different studies, it's probably not valid to directly compare numbers from different studies.
acute vs. subacute effusions causing tamponade
- Over time, the pericardium can stretch to accommodate a greater volume.
- Subacute tamponade (e.g., due to malignancy) may occur with very large effusions (e.g., 1-2 liters).
- Acute tamponade (e.g., due to traumatic hemopericardium) may occur with ~50 ml of pericardial blood, because the pericardium doesn't have time to stretch.
- 💡 Don't assume that tamponade will always be associated with a huge effusion that is easily visualized on ultrasonography.
relationship of pericardial volume versus pressure
- The physiological effect of the effusion depends on the pressure of the effusion – not the volume.
- As the volume of the pericardial effusion increases, the pressure initially rises slowly. However, at a certain point the pericardium can't expand further – so any increase in volume causes a large increase in pressure (the “steep” portion of the curves above).
- The clinical significance of this:
- (1) Removing a relatively small amount of fluid may be sufficient to cause hemodynamic stabilization (e.g., removal of 50 ml from a 500-ml effusion, or alternatively, removal of 5 ml from a 50-ml effusion).
- (2) Patients may rapidly deteriorate following small increases in pericardial fluid.
Central venous pressure (CVP) versus pericardial pressure
Venous Inflow = (CVP) – (RA pressure)
RA pressure ~ Pericardial pressure
Venous Inflow ~ [(CVP) – (Pericardial pressure)]
- The crux of pericardial tamponade is that the effusion increases pressure in the right atrium (RA pressure). This impairs venous inflow into the heart (which is driven by the pressure gradient between the central venous pressure and the right atrial pressure; formula above).
- Initially, increased pericardial pressure can be compensated for with increased central venous pressure (e.g., following volume administration).
- If the pericardial pressure rises high enough, it becomes impossible to compensate with an increased central venous pressure, for a few reasons:
- Excessive increase in central venous pressure causes venous congestion, which impairs systemic perfusion.
- Eventually, patients with tamponade develop left atrial collapse with impaired inflow of blood into the left side of the heart. Increasing the central venous pressure may preserve venous inflow into the right atrium, but it cannot restore blood flow into the left atrium. Indeed, excessive elevation of the CVP could theoretically cause dilation of the right atrium and right ventricle – further impairing the filling of the left heart.
final cause of death in pericardial tamponade
- The precipitating cause of death may be a drop in arterial pressure below a level that allows perfusion of the coronary arteries. This causes a rapid spiral of cardiovascular collapse.
- Terminal cardiovascular collapse may be precipitated by a vagal reaction (a phenomenon referred to as the “last drop”). (29025544)
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- Failing to perform bedside echocardiography on every shock patient.
- Delaying pericardial drainage in a crashing patient in order to perform a more complete echocardiogram.
- Tamponade due to acute bleeding into the pericardium may occur with a small-moderate effusion, because the pericardium hasn't had time to stretch open. This may not be obvious on a brief bedside echocardiogram.
- Post-CABG tamponade may occur due to a focal clot within the pericardium that may be impossible to see with some echocardiographic views.
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References
- 09665212 McGee SR. Physical examination of venous pressure: a critical review. Am Heart J. 1998 Jul;136(1):10-8. doi: 10.1016/s0002-8703(98)70175-9 [PubMed]
- 12057571 Bilchick KC, Wise RA. Paradoxical physical findings described by Kussmaul: pulsus paradoxus and Kussmaul's sign. Lancet. 2002 Jun 1;359(9321):1940-2. doi: 10.1016/S0140-6736(02)08763-9 [PubMed]
- 23809089 Nagdev A, Mantuani D. A novel in-plane technique for ultrasound-guided pericardiocentesis. Am J Emerg Med. 2013 Sep;31(9):1424.e5-9. doi: 10.1016/j.ajem.2013.05.021 [PubMed]
- 23891285 Argulian E, Messerli F. Misconceptions and facts about pericardial effusion and tamponade. Am J Med. 2013 Oct;126(10):858-61. doi: 10.1016/j.amjmed.2013.03.022 [PubMed]
- 25564921 Mansoor AM, Karlapudi SP. Images in clinical medicine. Kussmaul's sign. N Engl J Med. 2015 Jan 8;372(2):e3. doi: 10.1056/NEJMicm1310957 [PubMed]
- 28087158 McCanny P, Colreavy F. Echocardiographic approach to cardiac tamponade in critically ill patients. J Crit Care. 2017 Jun;39:271-277. doi: 10.1016/j.jcrc.2016.12.008 [PubMed]
- 29025544 Appleton C, Gillam L, Koulogiannis K. Cardiac Tamponade. Cardiol Clin. 2017 Nov;35(4):525-537. doi: 10.1016/j.ccl.2017.07.006 [PubMed]
- 29137910 Kearns MJ, Walley KR. Tamponade: Hemodynamic and Echocardiographic Diagnosis. Chest. 2018 May;153(5):1266-1275. doi: 10.1016/j.chest.2017.11.003 [PubMed]
- 30037442 Honasoge AP, Dubbs SB. Rapid Fire: Pericardial Effusion and Tamponade. Emerg Med Clin North Am. 2018 Aug;36(3):557-565. doi: 10.1016/j.emc.2018.04.004 [PubMed]
- 30471929 Alerhand S, Carter JM. What echocardiographic findings suggest a pericardial effusion is causing tamponade? Am J Emerg Med. 2019 Feb;37(2):321-326. doi: 10.1016/j.ajem.2018.11.004 [PubMed]
- 32572594 Flint N, Siegel RJ. Echo-Guided Pericardiocentesis: When and How Should It Be Performed? Curr Cardiol Rep. 2020 Jun 22;22(8):71. doi: 10.1007/s11886-020-01320-2 [PubMed]
- 35696801 Alerhand S, Adrian RJ, Long B, Avila J. Pericardial tamponade: A comprehensive emergency medicine and echocardiography review. Am J Emerg Med. 2022 Aug;58:159-174. doi: 10.1016/j.ajem.2022.05.001 [PubMed]