CONTENTS

• Rapid Reference: Approach to RV failure 🚀
• Diagnosis of RV failure
  • Defining RV failure
  • Clinical manifestations of RV failure
    • Congestive nephropathy
    • Congestive encephalopathy
    • Congestive hepatopathy
  • Laboratory findings
  • Radiological findings
    • Chest radiograph
    • CT scan
  • ECG
  • Echocardiography
  • POCUS evaluation of venous congestion
    • IVC
    • Femoral vein doppler
    • Portal vein pulsatility
• Causes of right ventricular failure
  • [1] Elevated afterload (pulmonary hypertension)
  • [2] Elevated preload (volume overload)
  • [3] Impaired contractility (RV myocardial dysfunction)
• Treatment
  • 1st Tier: Core treatments for all RV failure patients:
    • Correct any precipitating factors
    • Optimize the lungs
    • Volume management
    • Heart rate & rhythm optimization
    • Establish an adequate MAP
  • 2nd Tier: Often needed:
    • Pulmonary vasodilators
    • Inodilators
• Related/background information:
  • Intubation in RV failure
  • Preamble: Don't forget the right ventricle!
  • Pathophysiology of RV failure
    • RV death spiral
    • RV myocardial perfusion
    • Falling off the Starling curve
    • Occult systemic hypoperfusion
  • High-output heart failure

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rapid reference: approach to RV failure

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correct any precipitating factors 📖

• D/C negative inotropes (e.g., beta-blockers, dexmedetomidine).
• D/C systemic vasodilators (if hypotensive).
• Manage acidosis.
• Treat other active processes (e.g., infection, pulmonary embolism).

optimize the lungs 📖

• Aggressive oxygenation (O2 is a pulmonary vasodilator).
• Treat hypercapnia (but avoid intubation).
• Consider drainage of any substantial pleural effusions.
• If intubated, avoid excess PEEP.

volume management 📖

• Avoid fluid administration unless there is unequivocal hypovolemia.
• Most patients require diuresis (even if on vasopressors).
• Volume management:
  • Invasive strategy: If CVP >>12, may diurese to a target CVP of ~8-12 mm.
  • Noninvasive strategy: POCUS indicators of systemic congestion. ⚡️

heart rate & rhythm optimization 📖

• Manage arrhythmia (e.g., cardioversion of new AF).
• Treat bradycardia or inappropriate normocardia.

establish an adequate MAP 📖

• Target a MAP >65 mm, or perhaps >(60 + CVP).
• Choice of agent?
  • 🏆 Vasopressin may be preferred if central access is available.
  • Mildly unstable: norepinephrine is often effective.
  • Sickest patients: consider 🏆 epinephrine.

inotrope PRN 📖

• Consider for:
  • RV systolic failure.
  • Poor perfusion.
  • Bradycardia or inappropriately low heart rate.
• Options include:
  • 🏆 Milrinone (best pulmonary vasodilation).
  • Dobutamine.
  • Epinephrine.

inhaled pulmonary vasodilators PRN 📖

• Indications may include:
  • Refractory hypoxemia (especially with R ➡️ L shunt).
  • Poor perfusion.
  • High risk of death (e.g., peri-intubation stabilization).
• Main contraindication: Left ventricular failure (inhaled pulmonary vasodilators carry a risk of increasing the pulmonary capillary wedge pressure with worsening of cardiogenic pulmonary edema).
• May combine iNO and epoprostenol for refractory patients.

other pulmonary vasodilators

• Milrinone.
• Chronic PH therapies should be continued.
• Sildenafil may be considered in extreme situations.

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defining RV failure

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getting started

• There is no universal definition of RV failure. (29744563)
• Technically, the RV could fail in two ways:
  • “Forwards failure” – RV fails to generate an adequate cardiac output, leading to cardiogenic shock.
  • “Backwards failure” – RV fails to decongest the systemic venous system, leading to an excessively high central venous pressure with systemic congestion.
• Physiologically, RV failure nearly always involves systemic congestion. (Isolated “forward failure” of the RV is extremely rare in the absence of marked hypovolemia.)

stages of RV failure

• [1] Systemic congestion (“backward failure” of the RV):
  • Markedly elevated CVP (central venous pressure) usually indicates RV failure in the absence of an obvious alternative explanation (e.g., severe hypervolemia, intubation with high airway pressures, abdominal compartment syndrome, pericardial tamponade).
  • Initially, systemic congestion may cause tissue edema without hypoperfusion.
• [2] Hypoperfusion without frank hypotension (“occult systemic hypoperfusion”)
  • Severe congestion can cause organ hypoperfusion without obvious hypotension.
  • The systemic perfusion pressure equals (MAP – CVP).  Patients with markedly elevated CVP and borderline reduced MAP may develop organ hypoperfusion.  For example:
    • Congestive encephalopathy (delirium with agitation, confusion, or drowsiness).
    • Congestive nephropathy with reduced urine output.
• [3] Frank hypotension with shock.
  • This is extremely dangerous because it causes a “double hit” to the systemic perfusion (MAP-CVP) in terms of both an elevated CVP and a reduced MAP.
  • Bowel wall edema may promote bacterial translocation and systemic inflammation, adding a component of vasodilatory shock. (30545979)

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clinical manifestations of RV failure

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most common manifestations of RV failure

history elements that suggest RV failure

• Very substantial weight gain.
• Increasing peripheral edema.
• Early satiety, abdominal fullness, right upper quadrant tenderness.
• Exercise intolerance, dyspnea on exertion. (36947468)

systemic congestion is usually present (unless RV failure is extremely acute)

• Peripheral edema.
• Jugular vein distension.
• Congestive hepatopathy:
  • Ascites.
  • Hepatic distension may cause right upper quadrant pain. (32284101)

shock with hypoperfusion eventually occurs

• Cool and clammy extremities, with poor capillary refill.
• Reduced urine output is an early finding (due to congestive nephropathy).
• Encephalopathy:
  • Isolated left ventricular failure usually doesn't cause delirium until cardiac output is profoundly reduced.
  • Right ventricular failure may cause delirium relatively early in the disease course (congestive encephalopathy, discussed further below ⚡️).

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congestive nephropathy

pathophysiology involves a vicious cycle

• Renal hypoperfusion causes sodium retention, leading to worsening systemic congestion (in a vicious cycle).
• Additional contributing factors may include:
  • Elevated intra-abdominal pressure may contribute to poor renal function.
  • Ascites accumulation can be involved.
  • Renal dysfunction may eventually cause anuria, promoting further fluid accumulation.

clinical features of congestive nephropathy

• Heart failure:
  • Especially heart failure involving the right ventricle.
  • However, renal venous congestion can occur even in the absence of detectable right ventricular dysfunction on echocardiography. (33258308)
• Clinical features of systemic venous congestion (discussed above).
• Renal function may be improved by decongestion and/or drainage of ascites.
• Brain natriuretic peptide levels may be substantially elevated.
• Proteinuria can occur. (33258308)

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congestive encephalopathy

epidemiological causes

• Right heart failure with systemic congestion is probably the most common cause (although the vast majority of cases are undiagnosed).
• AV fistula formation for the management of renal failure is the most commonly reported etiology (onset may occur years later). (33791065)
• Dural arteriovenous shunts.

clinical presentation

• [1] Other features of systemic congestion are present.
• [2] Neurological features:
  • This generally manifests as delirium (with fluctuating encephalopathy).
  • Asterixis or diffuse myoclonus is often reported. (32624312)
  • Seizures may occur.
  • Headache may be reported.
  • Intracranial pressure may be elevated (e.g., revealed by retinal nerve POCUS).
• [3] Clinical features may overlap with congestive hepatopathy (e.g., ammonia level can be elevated). (38682080)

imaging findings

• Vascular imaging studies may reveal prominent/dilated cerebral veins.
• Secondary intracranial hemorrhage can occur. (33791065)

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congestive hepatopathy

clinical features

• Congestive hepatopathy is generally asymptomatic. However, symptoms may include:
  • Jaundice (reflective of hyperbilirubinemia).
  • Right upper quadrant pain due to hepatomegaly.
  • Anorexia, early satiety. (33321947)
• Other features of right ventricular failure (e.g., peripheral edema) often dominate the clinical presentation. However, obvert ascites or peripheral edema can be absent. (33321947)

laboratory findings

• Hyperbilirubinemia is often the most prominent liver function abnormality.
  • Bilirubin is mostly unconjugated.
  • Among stable patients, bilirubin is usually <3 mg/dL. (33321947)
  • Acute RV failure may cause striking hyperbilirubinemia.
• Alkaline phosphatase is usually normal or only slightly elevated in acute heart failure, but it may eventually elevate in chronic congestive hepatopathy. The absence of substantial elevation in alkaline phosphatase may help differentiate congestive hepatopathy from obstructive jaundice. (31041066)
• Transaminases are usually normal or mildly elevated. However, marked elevation of transaminases may be seen in patients with a combination of congestive hepatopathy plus ischemic hepatitis (i.e., elevated CVP plus reduced cardiac output).
• Hypoalbuminemia is often seen but rarely <2.5 mg/dL. (33032979) This seems to reflect protein-losing gastroenteropathy rather than synthetic hepatic failure.
• Brain natriuretic peptide levels are generally elevated.
• Lactate may be elevated.
• Ascites chemistries: ascites usually occurs in the absence of cirrhosis, with the following features:
  • Serum-ascites albumin gradient is >1.1 g/dL.
  • Protein level >2.5 g/dL (higher than in cirrhotic ascites). (33321947)

imaging findings are discussed below in the section on CT imaging ⚡️

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laboratory findings in RV failure may include

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• Congestive nephropathy with elevated creatinine.
• Congestive hepatopathy: ⚡️
  • Bilirubin elevation, with or without mild elevation of alkaline phosphatase.
  • Transaminases are often mildly elevated.
  • Mild hypoalbuminemia.
• Ischemic hepatitis: The combination of reduced cardiac output plus systemic congestion may promote malperfusion with markedly elevated transaminases (aka, shock liver). This can occur despite the absence of frank hypotension.
• BNP (brain natriuretic peptide) is generally elevated, but this is nonspecific.
• Lactate elevation may occur.

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radiological findings in RV failure: chest radiography

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radiological findings in RV failure: CT scan

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Reviewing archival CT images can also help sort out acute versus chronic RV failure. Findings may include the following:

contrast reflux in the IVC

• Contrast reflux is a sign of RV failure due to various etiologies (e.g., pulmonary embolism, tricuspid regurgitation, pericardial disease).
• Performance depends on how rapidly contrast is injected (31731905)
  • <3 ml/s (routine scan): 31% sensitive, 98% specific.
  • >3 ml/s (CT angiography): 81% sensitive, 69% specific.

right ventricular dilation

• [Right ventricle > left ventricle] suggests RV dilation. The maximal dimension of both ventricles should be measured (which often will not occur within a single CT cut).
  • Limitation: May be insensitive among patients with left ventricular enlargement.
• Transverse diameter >57 mm (♀) or >60 mm (♂). (33778499, 30240288)
  • The diameter is measured in a plane perpendicular to the septum.
  • Performance: sensitivity ~65%, specificity ~92%.
• Bowing of the interventricular septum may be seen in acute pulmonary embolism or chronic pulmonary hypertension. (26024596)

pulmonary artery dilation 

• Cutoffs:
  • [Pulmonary artery > Aorta] suggests pulmonary artery enlargement.
  • Pulmonary artery diameter >3 cm suggests enlargement. (36017548)
• Significance of PA dilation:
  • PA dilation reflects both the severity and duration of pulmonary hypertension.
  • Dilation may be absent in acute right ventricular failure. (33402372)

right ventricular wall thickness

• The normal right ventricular wall is thin (up to ~3 mm) and barely noticeable on CT scan (figure above). (26024596)
• Right ventricular outflow tract thickness >6 mm may suggest chronic pulmonary hypertension.(32342182)

pericardial effusion

• Pericardial effusion can have numerous etiologies, but in the context of right ventricular failure, this suggests chronic, severe pulmonary arterial hypertension.
• Pericardial effusion is discussed further below in the section on echocardiography.

CT evidence of congestive hepatopathy

• Basic imaging findings (seen on CT or ultrasound):
  • Hepatomegaly is often seen (which can be massive), but splenomegaly is usually absent. However, in advanced disease, this may transition to cirrhosis with a small, nodular liver.
  • Ascites occurs in ~25% of cases but usually isn't clinically significant. (31041066, 33032979) Ascites generally occurs in the absence of cirrhosis. (33321947)
• CT scan:
  • A speckled heterogeneous enhancement pattern may be seen in the parenchymal or portovenous phases of contrast. (33032979)
  • There is a greater prevalence of hypervascular nodules that behave similarly to focal nodular hyperplasia (with homogeneous arterial enhancement followed by subsequent isodensity). However, patients are also at increased risk of hepatocellular carcinoma, so caution is required with this diagnosis. (33032979)
• Portosystemic shunts are generally absent (since venous pressure is elevated everywhere). (33032979)

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electrocardiographic findings in RV failure

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Findings of acute and chronic right ventricular strain can be quite similar.  Prior EKGs and clinical context may be needed to differentiate between these two possibilities.  

(1) Acute right ventricular strain (usually due to PE, but may be due to any cause of acute pulmonary hypertension – such as acute asthma)

• Right bundle branch block (complete or incomplete).
• Terminal right-axis deviation:
  • Prominent terminal S-wave in Lead I.
  • Prominent S-wave in V6 (normally, V6 has no S-wave).
• T-wave inversion:
  • Right precordial leads.
  • Inferior leads (III > aVF).
• Severe cases may cause ST changes in various patterns:
  • STE in III and aVF, +/- anteroseptal leads.
  • Diffuse ST depression with ST elevation in aVR.
  • Right precordial ST depression can mimic a posterior MI.

(2) Chronic right ventricular hypertrophy (RVH)

• Tall R-wave in V1:
  • The most classic finding of RVH.
  • Defined in terms of R>S or R>7 mm.
  • Highly specific for RVH but insensitive.
• Terminal right-axis deviation:
  • Prominent terminal S-wave in Lead I (in some cases, S>R).
  • Prominent S-wave in V6 (normally, V6 has no S-wave).
• RV strain pattern: ST depression +/- T-wave inversion in V1-V4 and to a lesser degree in the inferior leads.
• Right atrial abnormality (especially increased P-wave amplitude in Lead II).

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echocardiography in RV failure

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IVC dilation

• This is an expected finding for most patients with RV failure.
• IVC evaluation is discussed further below: ⚡️

RV dilation

• RV dilation is generally seen in RV failure, with some suggesting that RV dilation should be part of the definition of RV failure. (37155123) However, RV failure can occur in the absence of RV dilation due to extrinsic compression of the RV (e.g., pericardial effusion or chronic constrictive pericarditis).  
• RV dilation is best appreciated in the subcostal four-chamber view in diastole:
  • Normally, the RV is <~60% the size of the LV.
  • Moderate RV dilation: RV is ~60-100% the size of the LV.
  • Severe RV dilation: The RV is larger than the LV.

RV septal flattening (“D” sign)

• The D-sign refers to septal flattening observed in short-axis views of the heart (either via the parasternal or subcostal window).
• D-configuration in diastole suggests volume overload.
• D-configuration in systole suggests pressure overload (i.e., pulmonary hypertension).
• D-configuration throughout the cardiac cycle suggests a combination of both volume and pressure overload (as is often seen in advanced pulmonary hypertension).

TAPSE (tricuspid annular plane systolic excursion)

• TAPSE is the best single indicator of RV systolic function at the bedside.
• TAPSE is most precisely assessed via M-mode from an apical four-chamber view (if possible). However, visual estimation from other views may be used as well (e.g., subcostal).
• Grading:
  • Normal TAPSE: >17 mm. (33853435)
  • Mild RV dysfunction: 10-17 mm.
  • Moderate RV dysfunction: 5-10 mm.
  • Severe RV dysfunction: <5 mm.

TR jet & PASP (PA systolic pressure)

PASP = CVP + 4(max TR jet in m/s)²

• Tricuspid regurgitant jet:
  • The tricuspid regurgitant jet can be measured by using a continuous wave doppler (CW) placed across the tricuspid valve. The advantage of focusing on the tricuspid regurgitant jet is that this is directly measurable, thereby avoiding ambiguities involved in the estimation of CVP.
  • Peak tricuspid regurgitant velocity <2.8 m/s: pulmonary hypertension is unlikely.
  • Peak tricuspid regurgitant velocity 2.9-3.4 m/s: grey zone (pulmonary hypertension is likely if there are other echocardiographic features of right ventricular dysfunction).
  • Peak tricuspid regurgitant velocity ≧3.4 m/s: pulmonary hypertension is highly likely. (33853435)
• PA systolic pressure (PASP):
  • Can be estimated based on the central venous pressure plus the maximal tricuspid regurgitant (TR) jet velocity, as shown above.
  • PA systolic pressure >35 mm suggests pulmonary hypertension. (26342901)
  • In one ICU study, PA systolic pressure could be estimated in only 60% of patients due to technical limitations. (33853435) In the absence of transesophageal echocardiography, this technique cannot be relied upon to be helpful in all patients.

signs of chronic pulmonary hypertension

• (1) RV wall thickening (>~5 mm measured at end-diastole) suggests chronic pulmonary hypertension. This is best measured via parasternal long axis or subcostal windows. However, wall thickening may increase within 48 hours, so this can develop rapidly in the context of acute pulmonary hypertension. RV wall thickening >10 mm suggests that the PA pressure may be approaching systemic pressures. (28024557)
• (2) PA systolic pressure >60 mm suggests chronicity since a hypertrophied right ventricle is required to generate this much pressure (an acute increase in PASP >60 mm in an unconditioned right ventricle is probably inconsistent with survival).
• (3) A pericardial effusion is often an indicator of severe, chronic pulmonary arterial hypertension. (36116812)
  • Pericardial effusion results from elevated venous pressures, which impair the drainage of lymph via the coronary sinus.
  • ⚠️ Pericardial drainage can worsen RV dilation and intraventricular septal flattening, precipitating cardiovascular collapse.  Consequently, chronic pulmonary arterial hypertension is a relative contraindication to pericardiocentesis. Management should focus on global hemodynamic optimization (if filling pressures can be improved, the effusion will eventually resolve). (37973349)

bedside echo bubble study to evaluate severe hypoxemia

• Patients with pulmonary hypertension may suddenly develop severe hypoxemia due to opening up a patent foramen ovale (PFO), with subsequent intracardiac shunting of deoxygenated blood into the systemic circulation.
• Echocardiography during injection of agitated saline may rapidly evaluate for a right-to-left shunt in patients with right ventricular failure and severe hypoxemia. The appearance of bubbles in the left ventricle within <6 beats after the appearance of bubbles in the right ventricle indicates an intracardiac shunt (whereas delayed shunting may result from pulmonary arteriovenous malformations). (33853435)
• The presence of a right-to-left shunt should serve as a stimulus for more aggressive reduction of pulmonary artery pressures (e.g., inhaled pulmonary vasodilators, vasopressors to increase the systolic/pulmonary pressure gradient, diuresis).

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POCUS evaluation of venous congestion

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basic concepts: evaluation of venous congestion

• Traditionally, venous congestion has been assessed based on either the IVC or the CVP (central venous pressure). This is an excellent starting point (e.g., if the IVC is small, then significant venous congestion is largely excluded). However, the addition of other indices may help confirm and quantify the degree of venous congestion.
• The primary indices that have been studied include hepatic vein Doppler, portal vein Doppler, interlobar renal venous flow, and femoral vein flow (figure below).

VExUS

• VExUS (venous excess ultrasound score) is a combination of IVC diameter with hepatic vein Doppler, portal vein Doppler, and interlobar renal venous flow (as shown below).
• VExUS illustrates a general approach to the evaluation of venous congestion:
  • [#1] Start with the IVC.  If the IVC appears normal, congestion is largely excluded.
  • [#2] If the IVC appears congested, secondary indices may be used to confirm the presence of congestion and grade its severity.
• The evidentiary basis for VExUS includes:
  • VExUS grade 3 has a high sensitivity (~100%) and specificity of 85% for detecting patients with a right atrial pressure >12 mm. (37237315)
  • VExUS of 2-3 outperforms isolated CVP as a predictor of the risk of acute kidney injury. (35707749)
• In practice, the components of the VExUS score are often challenging to obtain in patients who are unable to hold their breath. Renal vein Doppler is especially difficult. Hepatic vein Doppler may be uninterpretable in the absence of simultaneous ECG leads (which are frequently not included with basic ultrasound machines).
• Evaluation of the IVC, femoral vein, and portal vein may be used as an alternative to VExUS (since these are technically easier to obtain and interpret). Ultimately, clinical judgment is required at the bedside to evaluate each component granularly and reach a conclusion regarding volume status.

limitations to POCUS evaluation of venous congestion

• The following conditions will often confound the evaluation of venous congestion:
• [1] Elevated intraabdominal pressure (including pregnancy, Valsalva maneuver, and end-inspiratory breath hold that may inadvertently cause a Valsalva maneuver).
• [2] IVC pathology (e.g., stenosis, thrombosis).
• [3] Marked respiratory distress with the use of accessory muscles for respiration.
• [4] Cirrhosis (may cause false-negative portal vein pulsatility).
• [5] Severe tricuspid regurgitation. (36464836)
  • Severe tricuspid regurgitation causes flow reversal in the hepatic vein Doppler sonography. However, flow reversal in the femoral vein seems to be less common due to isolated tricuspid regurgitation (without systemic congestion). (33985881) The explanation may be that in the absence of congestion, the IVC is distensible and doesn't transmit pressures to the femoral vein.

clinical utilization of venous congestion

Venous congestion = RV failure

Venous congestion ≠ Needs diuresis

• Venous congestion reveals right ventricular failure, but the presence of venous congestion doesn't explain why the right ventricle is failing or how this should be treated:
  • Venous congestion doesn't necessarily indicate that the patient should be diuresed. Many patients with venous congestion should be diuresed, but other patients require other treatments for right ventricular failure (e.g., pulmonary vasodilators or pericardial drainage for treatment of tamponade).
• 💡 Venous congestion should always be interpreted and acted upon in the context of global hemodynamic assessment (with a focus on right ventricular abnormalities, as discussed earlier in this chapter).
• Patients with chronic pulmonary hypertension may always have a high VExUS score, so this doesn't necessarily indicate aggressive diuresis. (36464836) Normalization of portal vein pulsatility might be a more useful therapeutic target in the context of chronic pulmonary hypertension (whereas IVC dilation and abnormal waveforms of the hepatic and femoral veins are irreversible). (35707749)

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IVC

basic technique

• IVC is assessed ~2 cm below the right atrial junction.
• Both short and long-axis views should ideally be examined. The short axis is preferred to avoid being confused by an oblong IVC.
• (⚠️ M-mode examination of the IVC is easily confounded by respiratory effort, which causes the IVC to move in and out of the ultrasound plane. M-mode adds little useful information beyond a careful examination of the longitudinal and short axis of the IVC.)

interpretation

• Normal IVC diameter is <2 cm with respirophasic variation. If seen, a normal IVC excludes systemic congestion (so the remainder of the VExUS scan is unnecessary).
• IVC diameter >2 cm suggests elevated CVP, especially if respirophasic variation is lacking.
• A circular vessel (rather than an elliptical shape) usually indicates elevated CVP. (38815571)

limitations 

• Athletes may have IVC dilation without elevated right atrial pressure. (36464836)
• Elevated intra-abdominal pressure may cause IVC collapse (despite elevated right atrial pressure). (36464836)
• Lower body surface area may correlate with a lower cutoff value (e.g., ~1.7 cm). (38815571)

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femoral vein

basic technique

• The common femoral vein is insonated using a vascular ultrasound probe with the patient in a supine position.
• PW (pulse wave) Doppler in the short axis (without angle correction) may provide a qualitative tracing of the flow. If the probe angle is dropped down to <30 degrees, then the flow velocities will be only mildly reduced (<25% reduction).
• PW (pulse wave) Doppler in the long axis with angle correction provides quantitative flow rates.
• A Doppler scale of +/- 20 cm/s may be useful.

interpretation

• [A] Absent flow during inspiration:
  • This suggests the collapse of the IVC with inspiration.
  • This pattern may be seen with hypovolemia and/or vasodilation.
• [B] Continuous flow:
  • Description:
    • Flow is mostly continuous, but there may be mild respirophasic variations.
    • The mean velocity is normally ~10 m/s. (36599030, 10924377)
    • The stasis index is zero (there is no reversal of flow).
  • Clinical significance: Right atrial pressure is likely to be normal, and right ventricular dysfunction is unlikely.
  • Note that a complete lack of respirophasic variation suggests proximal venous obstruction (e.g., due to iliac vein DVT, pregnancy, or a mass lesion). (33063023)
• [C] Phasic flow:
  • Description:
    • PRV (peak retrograde velocity) is <10 cm/s or <33-50% of the antegrade velocity.
    • A small retrograde “a” wave <5 cm/s is probably within the range of normal. (33063023)
    • The stasis index may be ~0-30% (the fraction of time blood flows retrograde). (35604591)
  • Clinical significance: this is mildly abnormal.
• [D] Bidirectional flow:
  • Description:
    • PRV (peak retrograde velocity) is >33-50% of the antegrade velocity. (37165284)
    • The stasis index may be >30% (the fraction of time blood flows retrograde). (35604591)
    • PRV (peak retrograde velocity) may be >10 cm/s.
    • Doppler flows may have a sinusoidal pattern. (33063023)
  • Clinical significance: This is severely abnormal.

limitations

• IVC pathology (either intrinsic or extrinsic compression) will alter waveforms.
• Deep vein thrombosis may blunt waveforms.

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portal vein Doppler

basic technique

• PW (pulse-wave) Doppler is used to evaluate the portal vein.
• The mid-axillary transhepatic window is often useful, with a slight upward tilt. (36464836)
• The portal vein pulsatility index (PVPi) is defined as [Vmax-Vmin]/Vmax. (32624312)
  • <30% pulsatility is normal.
  • 30-50% pulsatility is mildly abnormal.
  • >50% pulsatility is severely abnormal.

interpretation

• Normally, there is monophasic flow or minimal fluctuations.
• Systemic congestion causes greater pressure transmission across the hepatic sinusoids, causing the portal vein to develop pulsatility.

technical pitfalls

• Pseudo-pulsatility may result from the vein intermittently coming out of the plane of the ultrasound beam during respiration. In contrast, the true pulsatility of the portal vein should be synchronous with the patient's pulse (not respiration). (38815571)

limitations

• [1] Thin patients may have portal vein pulsatility without elevated right atrial pressure. (36464836)
• [2] Cirrhosis with portal hypertension:
  • This may cause portal pulsatility to be falsely absent despite the presence of venous congestion.
  • Portal pulsatility may occur without congestion (since the pressure reflects local pressure changes rather than the right atrial pressure). (35707749)
• [3] Portal vein thrombosis.

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hepatic vein Doppler

basic technique

• PW (pulse-wave) Doppler is performed 1 cm within the hepatic vein.
• An end-expiratory breath hold is helpful if possible.

interpretation

• Normal waveform:
  • A-wave: Small retrograde wave due to atrial contraction (immediately after P-wave on ECG).
  • S-wave: Occurs during systole, as the downward motion of the tricuspid annulus sucks blood into the atrium (immediately after R-wave on ECG). (35707749) Greater tricuspid annulus excursion may correlate with a larger S-wave so that a large S-wave may reflect a healthy RV. 
  • V-wave: may sometimes be seen due to the tricuspid annulus moving back upwards to its normal position (which increases the RA pressure). (36464836) Normally, the V-wave may be above or below the baseline. (35707749)
  • D-wave: occurs during diastole due to blood flow through the tricuspid valve (immediately after T-wave on ECG). Normally, the D-wave is smaller than the S-wave.
• Mildly abnormal:
  • D-wave becomes larger than the S-wave.
• Severely abnormal:
  • S-wave reversal.

limitations

• Tricuspid regurgitation: S-wave reversal may occur without significant systemic venous congestion. (36464836)
• Waveforms may be blunted by the following conditions: (36464836)
  • Cirrhosis or fatty infiltration of the liver; hepatic lymphoma.
  • Valsalva maneuver or end-inspiratory breath hold. (38815571)
  • Abdominal compartment syndrome.
  • IVC stenosis.
• Atrial fibrillation causes:
  • Loss of the A-wave.
  • The S-wave becomes smaller than the D-wave (since the S-wave depends partially on atrial relaxation). (36464836, 35707749)

technical pitfalls

• Without ECG leads, differentiating different waveform components is often impossible.
• A high wall filter setting on the ultrasound (which can be the default for some cardiac probes) may eliminate some components of the waveform. (38815571)

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renal vein Doppler

basic technique

• Evaluate the interlobar veins (between the medullary pyramids).
• This is often challenging, especially if the patient is unable to hold their breath.
• Tips:
  • A curvilinear transducer in the abdominal preset may be helpful.
  • Power Doppler may be more useful than color Doppler (since this is more sensitive to lower flow rates).
  • Ask the patient to hold their breath if they can.
  • Adjust the Doppler scale (usually 20 cm/s or less). (38815571)

interpretation

• Normally, the renal vein flow is continuous.
• Mild congestion produces S and D waves (similar to the hepatic vein).
• Severe congestion causes S-wave reversal (which will seem to disappear since it merges into the arterial waveform).

pitfalls/limitations

• Evaluation of the hilar vessels may show pulsatility (even in the absence of systemic congestion).
• Obstructive nephropathy may cause discontinuous intrarenal flow patterns. (33258308)
• Chronic kidney disease stage IV-V might cause pulsatility in the absence of congestion. (38815571)

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causes of right ventricular failure

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Right ventricular failure is usually partially or entirely due to excessive afterload (i.e., pulmonary hypertension). Unlike the left ventricle, the right ventricle tolerates increases in afterload poorly. (38031338) However, an individual patient will often have multifactorial RV failure. Identifying and treating all causative factors is essential.  A review of prior right ventricle imaging (if available) may help clarify whether there is a substantial component of chronic pulmonary hypertension.

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#1/3: excessive afterload (pulmonary hypertension)

chronic pulmonary hypertension

• Group 1: Pulmonary Arterial Hypertension (PAH)
  • 1.1 Idiopathic.
  • 1.2 Hereditary.
  • 1.3 Drug and toxin-induced (e.g., cocaine, chemotherapy).
  • 1.4 Pulmonary Arterial Hypertension associated with:
    • 1.4.1 Connective tissue disease (e.g., SLE, scleroderma).
    • 1.4.2 HIV.
    • 1.4.3 Portal hypertension.
    • 1.4.4 Congenital right-to-left shunt (e.g., atrial septal defect).
  • 1.5 Long-term responders to calcium channel blockers.
  • 1.6 Pulmonary veno-occlusive disease / pulmonary capillary hemangiomatosis.
• Group 2: Left heart disease (e.g., systolic failure, diastolic failure, valvular disease).
• Group 3: Lung disease and/or hypoxemia (e.g., COPD, interstitial lung disease, obesity hypoventilation syndrome).
• Group 4: Pulmonary artery obstruction.
  • 4.1 Chronic thromboembolic pulmonary artery hypertension (CTEPH).
  • 4.2 Other pulmonary artery obstructions.
• Group 5: Unclear/multifactorial:
  • Hematologic disorders (e.g., myeloproliferative disorders, splenectomy, sickle cell anemia).
  • Sarcoidosis.
  • External compression of the pulmonary arteries.
  • End-stage renal disease requiring dialysis. (32740380, 32115291)

acute pulmonary hypertension

• PE (pulmonary embolism)
  • Massive PE can cause acute-onset pulmonary hypertension. 📖
  • Moderate-size PE may cause decompensation among patients with chronic pulmonary hypertension.
• Lung disease (e.g., any cause of hypoxemia and/or hypercapnia). (28024557)
  • ARDS
    • ~25% of patients with ARDS may have RV dysfunction. (29744563)
    • Risk factors for RV dysfunction include:
    • (1) Severe hypoxemia (e.g., PaO2/FiO2 < 150).
    • (2) Hypercapnia (e.g., PaCO2 > 48 mm).
    • (3) High airway pressures.
    • (4) Pneumonia.(33853435, 29744563)
  • Pneumonia.
  • Lung overdistension: excessive PEEP or autoPEEP.
  • Lung underdistention: atelectasis, pleural effusion, pneumothorax.
  • Sickle cell acute chest syndrome (~20% incidence of RV failure).(29744563)
• Alpha-agonists:
  • Excessive doses of phenylephrine or norepinephrine.
  • Oral decongestants (e.g., neosynephrine) may exacerbate chronic PH.
• Nonadherence with pulmonary hypertension therapy.

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#2/3: excessive preload (volume overload)

• Hypervolemia is a common precipitant of RV failure.
• Tricuspid regurgitation (e.g., tricuspid endocarditis).
• Pulmonic regurgitation.
• VSD (ventricular septal defect).
• High-output heart failure. ⚡️

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#3/3: impaired contractility (primary RV myocardial dysfunction)

• Negative inotropic medications:
  • Beta-blockers.
  • Diltiazem, verapamil.
  • Dexmedetomidine.
• Arrhythmia (e.g., atrial fibrillation, bradycardia).
• Septic cardiomyopathy
  • Cytokine release may increase the pulmonary vascular resistance and reduce right ventricular contractility. (33541609, 32740380)
  • Roughly a third of patients may have RV dysfunction.
  • Recognition of RV dysfunction may be especially important because this may be exacerbated by many treatments of septic shock (e.g., large-volume fluid administration).
• Post-cardiac arrest myocardial dysfunction.
• Right ventricular myocardial infarction (RVMI). 📖
• Status post cardiac surgery.
• Myocarditis (usually in combination with LV dysfunction; RV dysfunction on CMRI is a strong predictor of mortality). (36947468, 37155123)
• Rare:
  • ARVC (arrhythmogenic right ventricular cardiomyopathy).
  • Sarcoidosis (rarely may cause predominant right ventricular dysfunction). (36947468)

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correct any precipitating factors

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Any factors promoting pulmonary hypertension should be treated if possible, for example:

• Discontinuing medications, e.g.:
  • Negative inotropes.
  • Systemic vasodilators.
  • Alpha-agonists.
  • Dexmedetomidine.
• Treat any metabolic acidosis.

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optimize the lungs

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Any pulmonary dysfunction will increase the pulmonary vascular resistance, thereby increasing the afterload on the right ventricle.

[#1] liberal oxygen

• Oxygen is the original pulmonary vasodilator.
• Aggressive oxygen may reduce pulmonary vascular resistance and improve cardiac output.

[#2] optimize lung function, for example: 

• Drainage of moderate/large pleural effusion.
• CPAP/BiPAP for management of atelectasis, COPD, or OHS (obesity hypoventilation syndrome).

[#3a] if not intubated: avoid intubation

• Avoid intubation if possible, as this is an extremely high-risk procedure in the context of right ventricular failure (more on the intubation procedure below).
• A high-flow nasal cannula may be a safe and noninvasive strategy to improve oxygenation and ventilation (among patients who don't have an indication for CPAP or BiPAP).

[#3b] if intubated: optimize ventilator settings

• (a) Maintain an adequate oxygen saturation, with generous oxygen administration as above.
• (b) Avoid hypercapnia as able:
  • CO2 is a pulmonary vasoconstrictor.
  • Hypercapnia should be treated, if possible, with a goal of normocapnia.
• (c) Avoid using excessive PEEP or mean airway pressure. However, using adequate PEEP to prevent atelectasis remains beneficial, as this will recruit lung tissue and thereby reduce pulmonary vascular resistance.

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volume management

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optimizing volume status in RV failure

• Fluid administration is rarely beneficial for patients with RV failure. It should not be administered unless there is definite volume depletion.
• Hypervolemia is generally present and usually requires diuresis (physiology discussed below: 📖).

decongestion as a diuresis target

• CVP:
  • CVP is generally not very helpful in the ICU because we often try to use it as a surrogate for left-sided filling pressures (something the CVP is awful at). However, in right heart failure, we are actually interested in right-sided filling pressures, so the CVP actually measures what we need.
  • Consensus suggests that a reasonable target might be a CVP of ~8-12 mm (i.e., slightly elevated filling pressures). (32740380, 32411259, 24828526, 30190155, 38031338)  The optimal role of the CVP here is as a tool to encourage diuresis (rather than to stimulate fluid administration).
  • 💡 If the CVP is >>12, this may provide reassurance that diuresis is likely safe.
• POCUS indices of systemic venous congestion may also help guide volume optimization:
  • POCUS evaluation of venous congestion
    • IVC
    • Femoral vein doppler
    • Portal vein pulsatility

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heart rate & rhythm optimization

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• Atrial fibrillation:
  • AF is especially problematic because atrial contraction accounts for >40% of RV filling. (37155123)
  • When possible, the optimal treatment may be the restoration of normal sinus rhythm.
  • Beta-blockers or diltiazem should be avoided, given their negative inotropic properties.
  • For patients who cannot be cardioverted, digoxin may be a good option for providing rate control and positive inotropy. More on the management of critical AF here.
• Bradycardia is often very poorly tolerated and suggestive of imminent death in some contexts. This must be treated aggressively (as discussed here).
• Inappropriate normocardia: Heart rate within a “normal” range (e.g., 80-90 b/m) in the context of cardiogenic shock may represent an inappropriate compensatory response. Such patients might theoretically benefit from a positive inotrope to improve heart rate and cardiac output (e.g., dobutamine infusion).

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establish an adequate MAP

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why maintaining an adequate MAP is important:

1. An adequate MAP will promote adequate perfusion of the right ventricular myocardium.
2. An adequate MAP is necessary to perfuse the kidneys (allowing for diuresis, if needed).
3. A higher MAP will increase the LV afterload, which may counteract septal flattening and thereby promote normal cardiac geometry. (33541609)
4. Among patients with a patent foramen ovale and right-to-left shunting, elevation of left-sided pressures may help reduce the amount of shunting.

optimal target MAP?

• MAP >65 mm is a reasonable place to start.
• MAP >(60 mm + CVP)
  • Patients with markedly elevated CVP might need a higher MAP target to achieve adequate systemic perfusion pressures.
  • A reasonable target MAP might be >(60 mm + CVP).
  • Patients with systemic congestion and low MAP may require a combination of simultaneous vasoconstrictors plus diuresis (to promote decongestion and optimization of right ventricular preload).
  • When in doubt, it may be reasonable to trial an elevated MAP to determine if this causes clinical improvement (e.g., improved urine output)(figure below).
  • Once the patient has been adequately decongested, vasoconstrictors can often be weaned. At this point, the patient may be able to clinically tolerate a lower MAP without hypoperfusion (because, due to the lower CVP, the systemic perfusion pressure is now adequate at a lower MAP).
• SBP > RVSP
  • To ensure RV perfusion, the systemic systolic blood pressure should be kept well above the RV systolic blood pressure (SBP >> RVSP).
  • This usually isn't difficult to achieve, but for patients with chronic, severe pulmonary hypertension, it may be an issue. (32284101) 

choice of agent

• 🏆 Vasopressin is arguably the ideal agent since it offers the ability to increase MAP while simultaneously reducing pulmonary vascular resistance. (33541609) The limitations of vasopressin include that it is difficult to titrate, it is not safe for peripheral administration, and it will often be insufficient among patients with profound hypotension (because it is typically not titrated above 0.06 units/min).
• Epinephrine is a good choice among the sickest patients. At lower doses, epinephrine may function more as an inotrope, whereas at increasing doses, it will function more as a vasoconstrictor. The beta-agonist activity of epinephrine will reduce pulmonary vascular resistance and support right ventricular function, thereby improving the MAP without worsening RV afterload.
• Norepinephrine is a reasonable choice that is commonly used. Norepinephrine is easy to titrate and safe for peripheral administration. It is immediately available in most contexts. However, norepinephrine does function predominantly as an alpha-agonist, so it may increase pulmonary vascular resistance (especially at higher doses). (32740380)

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pulmonary vasodilators

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inhaled pulmonary vasodilators

• These offer numerous benefits:
  • (1) Improvement in oxygenation and ventilation due to improved ventilation-perfusion matching.
  • (2) Reduced pulmonary vascular resistance, which improves right ventricular failure.
  • (3) Administration via inhalation generally doesn't cause systemic vasodilation or systemic hypotension (because the drug selectively vasodilates the pulmonary vasculature).
• The main contraindication to inhaled pulmonary vasodilators is severe left ventricular failure or pulmonary veno-occlusive disease. By increasing blood flow through the right ventricle, pulmonary vasodilators may increase the left ventricular preload. This could precipitate cardiogenic pulmonary edema among patients with left ventricular dysfunction.
• The exact indication for pulmonary vasodilators in right ventricular failure is unknown. Potential indications include:
  • (1) Refractory hypoxemia (especially in the presence of a right-to-left shunt due to a patent foramen ovale).
  • (2) Stabilization in the peri-intubation period.
  • (3) RV failure patients with a high risk of mortality.
  • (4) Failure to respond to less aggressive treatments, as listed above.
• In the direst situations, multiple different pulmonary vasodilators may be used simultaneously to utilize different mechanisms of action on the pulmonary vasculature (e.g., nitric oxide plus epoprostenol).
• (For further discussion, see the chapter on inhaled pulmonary vasodilators.)

milrinone

• Discussed in the section below 👇.

nitrates

• Nitroprusside 💉 causes pulmonary vasodilation, but its utility may be limited by its effects on systemic vascular resistance.
• Nitroglyercine 💉 seems to be a less potent pulmonary vasodilator, but it may have a superior safety profile compared to nitroprusside. (16387672, 15947535)

intravenous prostacyclins

• Intravenous pulmonary vasodilators (e.g., epoprostenol) should always be continued for patients who were previously on them.
• Rarely, IV epoprostenol might be initiated in the ICU for a patient with known pulmonary arterial hypertension (Type-1 pulmonary hypertension). The use of intravenous pulmonary vasodilators is trickier than inhaled pulmonary vasodilators for three reasons:
  • (1) Intravenous pulmonary vasodilators may cause systemic vasodilation, reducing the systemic blood pressure.
  • (2) Intravenous pulmonary vasodilators will impair ventilation-perfusion matching, which may worsen oxygenation and ventilation.
  • (3) Intravenous pulmonary vasodilators may function as a bridge to long-term intravenous pulmonary vasodilator use. Thus, they may be most suitable for patients who are candidates for long-term intravenous pulmonary vasodilator therapy.

sildenafil

• Enteral sildenafil appears to be safe and effective in reducing pulmonary pressures. It has predominantly been investigated following cardiothoracic surgery. (30685151, 24987174, 24613188, 22057829, 21513610) The dose studied has often been ~20 mg q8hr.
  • Oral sildenafil can help facilitate the withdrawal of inhaled pulmonary vasodilators if there is difficulty weaning off them, although there isn't robust evidence to support this. (15620942, Dabbagh 2018, Sundt 2022)
• Sildenafil has not been well studied among the general ICU population. This might be considered in a context where all other therapies are failing. There is a risk that nonspecific pulmonary vasodilation could worsen ventilation/perfusion matching and thereby exacerbate hypoxemia. (20130830)

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inotrope

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benefits

• (1) Positive inotropy may improve RV function.
• (2) Vasodilation of the pulmonary vasculature may reduce the RV afterload.
• (3) Increased heart rate may increase cardiac output (for patients with relatively slow heart rate).

risks/contraindications

• (1) There may be a risk of tachyarrhythmia (especially atrial fibrillation).
• (2) Increasing contractility may exacerbate relative ischemia of the right ventricle.
• (3) Systemic vasodilation may promote hypotension.

clinical indications to consider inotropic therapy may include: 

• (1) Systolic failure of the right ventricle (e.g., reduced TAPSE).
• (2) Inadequate systemic perfusion (especially if this occurs despite other measures – such as pulmonary vasodilators, volume optimization, and/or vasoconstrictor support).
• (3) Bradycardia, or a heart rate that seems inappropriately low (given the current level of physiological stress).

three options to add inotropy

• Epinephrine:
  • Epinephrine functions mainly as an inotrope, especially at lower doses. However, it does have enough alpha activity to prevent hypotension, making it an attractive single agent for patients requiring substantive inotropy and vasoconstriction.
  • For patients on norepinephrine who require inotropic activity, the norepinephrine may be switched to epinephrine. Using epinephrine as a single agent may be a simple and practical approach.
  • Epinephrine stimulates cardiac beta-1 and beta-2 receptors, which may make it a more powerful inotrope than dobutamine (which selectively affects beta-1 receptors).
• Dobutamine: The usual dose range is 2-10 mcg/kg/min (at higher doses, there may be more significant systemic vasodilation causing hypotension). (33541609)
• 🏆 Milrinone: This is more difficult to titrate than dobutamine due to its longer half-life, especially in renal dysfunction. However, a larger body of evidence supports milrinone's ability to function as a pulmonary vasodilator.

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intubation in severe pulmonary hypertension

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Intubation is fraught with peril for the patient with substantial RV failure. Patients may respond poorly to hypoxemia, hypercapnia, positive pressure, and sedation. Patients and families should be informed regarding these risks and participate in informed consent when possible.

There are a variety of different ways to approach this. The ideal way is arguably a hemodynamically neutral intubation, but this may be difficult to achieve on an emergent basis in many units.

A more accessible strategy is roughly as follows:

• The more you can optimize the patient prior to intubation, the better. If there are fixable processes, it's ideal to fix these prior to intubation. For example:
  • Chest tube to drain a pneumothorax or pleural effusion.
  • Systemic thrombolysis for a submassive or massive PE.
  • Management of DKA (try to delay intubation as long as possible to allow more time for this).
• Stabilize the blood pressure with RV-friendly agents (e.g., vasopressin plus epinephrine). Target a moderately elevated MAP prior to intubation (e.g., ~80 mm) if possible, with the anticipation that the MAP will decrease following intubation.
• Consider the insertion of an arterial catheter.
• Plan the insertion depth of your endotracheal tube using MDCalc here.
• Place the patient on BiPAP with 100% FiO2. Gradually increase the BiPAP settings to a moderate amount of support (e.g., 18 cm/12 cm). Follow hemodynamics carefully and titrate vasopressors as needed to maintain a healthy blood pressure. BiPAP allows you to ease the patient onto positive pressure ventilation slowly and in a reversible fashion. BiPAP is also a great modality to preoxygenate the patient and avoid derecruitment during intubation.
• Consider the administration of a nebulized pulmonary vasodilator prior to intubation. Also, a pulmonary vasodilator at the bedside should be ready to be administered through the endotracheal tube as soon as the patient is intubated.
• Induce the patient with hemodynamically stable agents (e.g., ketamine plus rocuronium). Set the BiPAP device to provide apneic ventilation as the patient begins to become sedated until you are about to insert the endotracheal tube (e.g., as described here).
• Intubate the patient as quickly as possible and immediately connect the patient to the ventilator. Provide cautious, lung-protective ventilation. Avoid aggressively bagging the patient, as this may increase intrathoracic pressure and precipitate cardiac arrest.
  • Insert the ETT to the preplanned depth. Verify that it is not in the right mainstem bronchus.
• Immediately following intubation, initiate a pulmonary vasodilator at maximal dosage.
• Follow the patient's hemodynamics and capnographic waveform very closely for the following 15-30 minutes. This is a critical juncture when many patients may insidiously slip into an RV death spiral. Don't hesitate to aggressively escalate the epinephrine infusion if the blood pressure falls.
• Check a blood gas and avoid hypercapnia (if possible).

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preamble: don't forget the right ventricle!

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The right ventricle is sometimes called the forgotten ventricle. Many textbooks on critical care cardiology are written almost entirely about left ventricular failure. Likewise, nearly all evidence surrounding heart failure is with regard to the left ventricle. There is nearly no high-quality evidence regarding the management of right ventricular failure in the ICU.

Nonetheless, right ventricular failure is quite common in the ICU, occurring in perhaps about a third of patients with ARDS or septic shock. Our most important task in the ICU is identifying patients with RV failure and providing them with a basic RV-friendly resuscitation. Simple interventions can go a long way in these patients if we can merely understand their precarious physiology.

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pathophysiology of RV failure

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Four concepts are especially useful clinically.

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vicious spirals of RV failure

• RV failure tends to produce a set of vicious spirals, which tend to cause progressively worse failure (figure above). This is extremely dangerous because if left untreated, RV failure will tend to spiral out of control.
  • These spirals explain why patients with RV failure can sometimes suddenly die (a phenomenon often seen in patients with massive pulmonary embolism or following intubation).
• A central feature of RV failure is RV dilation, which causes shifting of the interventricular septum, as well as functional tricuspid regurgitation.

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RV myocardial perfusion

RV systolic perfusion pressure = (Systolic Bp) – (Pulmonary Artery Systolic Pressure)

• Unlike the left ventricle, the RV is normally perfused during both systole and diastole. Since the RV pressure is relatively low, the systemic pressure is greater than the RV pressure throughout the cardiac cycle – allowing perfusion to occur continuously. (32284101)
• Systolic perfusion of the right ventricle depends on the pressure gradient between the coronary arteries (the systolic blood pressure) and the right ventricle pressure (which is equal to the pulmonary artery systolic pressure) – as shown above.
• In RV failure, systemic hypotension may cause the systolic blood pressure to fall to levels close to the pulmonary artery systolic pressure. This will impair RV perfusion during diastole.
• Defending the RV myocardial perfusion depends on maintaining the RV systolic perfusion pressure, as shown above. This requires interventions that increase the systolic blood pressure and decrease the pulmonary artery systolic pressure.

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RV failure patients can fall off the Starling curve

• Traditionally, it has been taught that excess volume administered to patients with heart failure may cause ventricular dilation, leading to ineffective systolic contraction and a reduction in cardiac output. This is referred to as “falling off the Starling curve.”
• This phenomenon probably doesn't really occur acutely in patients with isolated left ventricular failure because the left ventricle is a thick-walled chamber with a fairly fixed volume. Thus, the left ventricle doesn't dilate acutely in response to volume overload.
• The phenomenon of falling off the Starling curve does occur in patients with right ventricular failure:
  • (1) Excess volume loading can cause acute dilation of the thin-walled right ventricle that leads to impaired right ventricular function and functional tricuspid regurgitation.
  • (2) RV dilation may compress the LV, leading to left-sided diastolic dysfunction.  In extreme cases, this may induce LV outflow tract obstruction (LVOTO).
  • (3) Systemic congestion impairs systemic organ perfusion (discussed in the section below).

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occult systemic hypoperfusion

Systemic Perfusion Pressure = (MAP – CVP)

• In isolated left ventricular failure, volume overload results in pulmonary edema. This causes overt hypoxemia, dyspnea, and pulmonary edema on chest X-ray – an obvious problem that demands immediate attention.
• In right ventricular failure, volume overload instead results in systemic congestion (with an elevated central venous pressure). Since systemic congestion doesn't result in any vital sign abnormality or dramatic symptomatology, it is often ignored until it is profound (leading to anasarca).
• Systemic congestion with elevated central venous pressure may lead to organ malperfusion because it reduces the systemic perfusion pressure (formula above). For example, a patient with a MAP of 60 mm and a CVP of 25 mm may have an extremely low systemic perfusion pressure (35 mm). This cannot be detected based on usual vital signs, so it may lead to occult organ failure. Organs that are particularly affected include the kidneys, liver, brain, and bowel.
• If patients deteriorate further and develop overt hypotension, visceral organs will suffer a “double hit” due to both the reduced MAP plus the elevated central venous pressure.

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high-output heart failure

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causes

• Chronic anemia.
• Thyrotoxicosis.
• Cirrhosis.
• Obesity (BMI >35 kg/m2).
• Pregnancy.
• Multiple myeloma.
• Thiamine deficiency (beri-beri).
• AV fistulas:
  • Shunt for hemodialysis.
  • Congenital AV fistula.
  • AV fistula 2/2 vascular intervention or trauma.
  • HHT (hereditary hemorrhagic telangiectasia).
• Other causes:
  • Paget disease.
  • Carcinoid syndrome.
  • Myeloproliferative hematologic disorders. (34353268)

clinical presentation

• Hemodynamics:
  • Warm extremities.
  • LV systolic function is (initially) preserved.
  • Wide pulse pressure due to reduced SVR (systemic vascular resistance).
  • Cardiac output is >8 L/min (or cardiac index >4 L/min/m2).
  • Mixed venous saturation >70-75%.
• Clinical manifestations may include:
  • Pulmonary congestion (tachypnea, pulmonary rales).
  • Systemic congestion (elevated CVP, peripheral edema).

echocardiography

• Ventricular function is initially preserved. Over time, this may progress to a dilated cardiomyopathy.
• Systemic congestion may be present (e.g., IVC dilation).

management

• ⚠️ Standard guideline-directed medical therapies for HFrEF may be dangerous in these patients (e.g., beta-blockade, ACE inhibitors).
• [1] Ideally, identification and reversal of the underlying process will treat the heart failure.
• [2] Vasoconstrictors may be considered to increase systemic vascular resistance (at least as a temporary stabilizing measure).
• [3] For patients with significant systemic congestion, diuresis may be beneficial. (18990720)

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questions & discussion

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To keep this page small and fast, questions & discussion about this post can be found on another page here.

• Don't leave the room within 10 minutes of intubating a patient with pulmonary hypertension. This is when they usually crash: once the ETT is in, everyone thinks that they're all set.
• Don't give fluid to a pulmonary hypertension patient unless you have an exceptionally good reason.
• If a pulmonary hypertension patient is chronically on an intravenous vasodilator, ensure that this is never interrupted.
• Don't ignore pulmonary hypertension. You don't need to be a rocket scientist to treat this, but you do need to try.

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