Predicting and Measuring Fluid Responsiveness
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1. A 75-year-old man presents to the Emergency Department complaining of fever and shortness of breath. Laboratory evaluation reveals white blood cell (WBC) count of 21,000/mm3 and a serum lactate level of 4.2 mmol/L. Chest X-ray demonstrates a left lower lobe infiltrate. During these tests, his BP drops to 80/60 mm Hg and he becomes somnolent. A bolus of 30 mL/kg of lactated Ringer’s solution is rapidly administered, and repeat BP measurement is 82/65 mm Hg. His oxygen saturation is also noted to decrease from 94% to 89% while on 2 L oxygen by nasal cannula. Point-of-care lung ultrasound ( Video 49.1) shows a representative image of his anterior lung fields—ultrasound findings were identical bilaterally.
What is the most appropriate next step?
A. Repeat 30 mL/kg intravenous fluid bolus
B. Provide supplemental oxygen via non-rebreather mask
C. Begin infusion of dopamine
D. Begin infusion of norepinephrine
1. Correct Answer: D. Begin infusion of norepinephrine
Rationale: Intravascular volume resuscitation is a core competency among healthcare providers managing acutely ill patients. Unfortunately, there are few definitive answers to questions such as when to infuse fluids and how much to administer to a hypotensive patient. Furthermore, increasing evidence of harm from over-resuscitation suggests that a more judicious approach to volume resuscitation may be appropriate. There is no single monitor or metric that is invariably predictive—thus, integrating data from different sources is often the most useful approach. Ultrasound-guided fluid resuscitation, in the context of other commonly used indices of predicting fluid responsiveness, may help guide volume resuscitation. This patient presented with severe sepsis (life-threatening organ dysfunction caused by a dysregulated host response to infection). Volume resuscitation is recommended as the initial intervention to improve perfusion by the Surviving Sepsis Guidelines, specifically, at least 30 mL/kg of crystalloid within the first 3 hours of presentation. However, some key pieces of information should cause us to pause before further volume resuscitation—the fact that his BP has not changed after intravenous volume expansion, and that his oxygen saturation is decreasing (Option A is incorrect). In the absence of a detailed past medical history (history of heart failure or chronic kidney disease, for example) and without further examination, it is difficult to define whether his desaturation is from pulmonary edema (either cardiogenic or noncardiogenic) or from decreased alveolar ventilation in the setting of increasing drowsiness and respiratory fatigue. The presence of a bilateral anterior B-line profile on lung ultrasound suggests significant extravascular lung water (EVLW). A bilateral B-line profile has been suggested to correlate with a PCWP >18 mm Hg, but this is not invariably true. While it is possible to have a bilateral B-line profile in noncardiogenic pulmonary edema, given his decreasing oxygen saturation and clear evidence of worsening EVLW, starting the patient on norepinephrine (the initial vasoactive medication of choice in severe sepsis or septic shock) is reasonable while a more detailed assessment is carried out regarding further therapy. Dopamine is associated with worse outcomes for sepsis when compared to norepinephrine (Option C is incorrect). While supplemental oxygenation is not unreasonable, there is no indication for a non-rebreathing mask—the degree of hypoxemia (SpO2 89% on room air) does not warrant a non-rebreather (Option B is incorrect).
1. Bentzer P, Griesdale DE, Boyd J, MacLean K, Sirounis D, Ayas NT. Will this hemodynamically unstable patient respond to a bolus of intravenous fluid? JAMA 2016;316:1298-1309.
2. De Backer D, Aldecoa C, Njimi H, Vincent JL. Dopamine versus norepinephrine in the treatment of septic shock: a meta-analysis. Crit Care Med. 2012;40(3):725-730.
3. De Backer D, Biston P, Devriendt J, et al. Comparison of dopamine and norepinephrine in the treatment of shock. N Engl J Med. 2010;362(9):779-789.
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6. Price S, Platz E, Cullen L, et al. Echocardiography and lung ultrasonography for the assessment and management of acute heart failure. Nat Rev Cardiol. 2017;14:427-440.
7. Rhodes A, Evans LE, Alhazzani W, et al. Surviving sepsis campaign: international guidelines for the management of sepsis and septic shock: 2016. Crit Care Med. 2017;45:486-552.
8. Singer M, Deutschman CS, Seymour CW, et al. The third international consensus definitions for sepsis and septic shock (sepsis 3). JAMA. 2016;315(8):801-810.
9. Volpicelli G, Skurzak S, Boero E, et al. Lung ultrasound predicts well extravascular lung water but is of limited usefulness in the prediction of wedge pressure. Anesthesiology. 2014;121:320-327.
2. You are evaluating the patient in Question 1 to determine additional interventions. Which of the following findings would be the most reliable indicator to withhold further fluid administration?
A. A central venous pressure (CVP) of 8 cm H2O
B. An inferior vena cava (IVC) maximal diameter of 2.3 cm, with >50% variation in respiration, measured by point-of-care ultrasound (POCUS)
C. No change in the velocity-time integral (VTI) obtained at the left ventricular (LV) outflow tract (LVOT) following a passive leg raise maneuver
D. An ejection fraction (EF) of 45% by point-of-care echocardiography
2. Correct Answer: C. No change in the velocity-time integral (VTI) obtained at the left ventricular (LV) outflow tract (LVOT) following a passive leg raise maneuver
Rationale: Frequent assessment of the patient’s clinical status should drive fluid administration, particularly as over-resuscitation has been shown to be associated with adverse consequences. A CVP of 8 cm H2O does not discriminate effectively between patients that will or will not benefit from additional intravascular volume expansion. The value of respiratory variation in IVC diameter in spontaneously breathing patients to determine fluid responsiveness is unclear. The EF by itself is not particularly useful in identifying patients who will increase their cardiac output following a fluid bolus. The change in the VTI at the LVOT in response to a passive leg raise maneuver can be used to predict volume responsiveness, by “autotransfusing” intravascular volume from the lower extremities into the central circulation and evaluating the change in stroke volume. Since the LVOT diameter remains constant in a given patient, stroke volume is directly proportional to the LVOT VTI. Given the information available, the absence of an increase in the VTI in response to passive leg raise predicts a lack of volume responsiveness (Figure 49.6). In this context, additional intravascular volume is unlikely to provide a hemodynamic benefit and more likely to exacerbate deleterious effects.
1. Airapetian N, Maizel J, Alyamani O, et al. Does inferior vena cava respiratory variability predict fluid responsiveness in spontaneously breathing patients? Crit Care. 2015;19:400.
2. Marik PE, Cavallazzi R. Does the central venous pressure predict fluid responsiveness? An updated meta-analysis and a plea for some common sense. Crit Care Med. 2013;41:1774-1781.
3. Vignon P, Repessé X, Bégot E, et al. Comparison of echocardiographic indices used to predict fluid responsiveness in ventilated patients. Am J Respir Crit Care Med. 2017;195:1022-1032.
3. A patient with septic shock is sedated and mechanically ventilated in the intensive care unit (ICU) and is becoming progressively more hypotensive. The patient’s arterial line tracing shows >30% pulse pressure variation. A rapid, focused, POCUS examination is performed to further investigate the cause of the pulse pressure variation. Which of the following ultrasound findings would argue against additional fluid resuscitation as the next step in care?
A. End-systolic effacement of LV walls (“kissing ventricle”) at the mid-papillary level on a parasternal short-axis window and an IVC with a maximum diameter of 0.8 cm
B. The presence of pericardial fluid in the subcostal long-axis view and a finding of diastolic inversion of the right ventricular (RV) free wall
C. An S′ velocity at the tricuspid annulus of 6 cm/s and diastolic flattening of the interventricular septum in the parasternal short-axis mid-papillary view
D. All the above findings suggest volume responsiveness
3. Correct Answer: C. An S′ velocity at the tricuspid annulus of 6 cm/s and diastolic flattening of the interventricular septum in the parasternal short-axis mid-papillary view.
Rationale: The findings in Option A are consistent with significant intravascular hypovolemia, which could present as pulse pressure variation and would likely respond to volume resuscitation. Echocardiographic features described in Option B are consistent with pericardial tamponade. Rapid volume expansion is a key supportive measure while definitive management (drainage or evacuation of the effusion) is being arranged, particularly in hypotensive patients (systolic BP <100 mm Hg). The findings described in Option C are consistent with RV dysfunction and volume overload of the right ventricle. RV dysfunction can also present with pulse pressure variation due to ventricular interdependence. One well-validated echocardiographic marker of RV systolic function is tissue Doppler interrogation (TDI) of the tricuspid annulus velocity (S′). An S′ velocity <10 cm/s is consistent with RV dysfunction (Figure 49.7). In the setting of RV dysfunction, further fluid administration should be undertaken with caution, if at all. A focused point-of-care echocardiography examination can rapidly differentiate between these three key causes of pulse pressure variation and, if available, should be considered in the evaluation of all hemodynamically unstable patients.
1. Magder S. Further cautions for the use of ventilatory-induced changes in arterial pressures to predict volume responsiveness. Crit Care. 2010;14(5):197.
2. Mahjoub Y, Pila C, Friggeri A, et al. Assessing fluid responsiveness in critically ill patients: false-positive pulse pressure variation is detected by Doppler echocardiographic evaluation of the right ventricle. Crit Care Med. 2009;37:2570-2575.
3. Rudski LG, Lai WW, Afilalo J, et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr. 2010;23(7):685-713.
4. Sagrista-Sauleda J, Angel J, Sambola A, Permanyer-Miralda G. Hemodynamic effects of volume expansion in patients with cardiac tamponade. Circulation. 2008;117:1545-1549.
4. A 64-year-old man presents with fevers, hypotension, and altered mental status. Blood cultures have grown methicillin-resistant Staphylococcus aureus (MRSA). An echocardiogram reveals a large vegetation on his mitral valve (see Video 49.2), with moderate to severe mitral regurgitation. He is deeply sedated and mechanically ventilated.
A pulmonary artery catheter is placed, and the pulmonary capillary wedge pressure (PCWP) is noted to be 16 mm Hg. With point-of-care echocardiography, the VTI at the LVOT is noted to vary by 25% with respiration. His blood lactate concentration is 7 mmol/L, and he is oliguric. Which of the following statements is most accurate?
A. Given his oliguria and lactic acidosis, renal replacement therapy with continuous venovenous hemofiltration (CVVH) should be initiated.
B. A PCWP of 16 mm Hg contraindicates further volume administration, as it is likely to induce pulmonary edema.
C. Epinephrine would be preferred over the combination of norepinephrine and dobutamine to support his cardiac output and BP.
D. Given a VTI variation of 25%, his cardiac output is likely to increase with a fluid bolus.
4. Correct Answer: D. Given a VTI variation of 25%, his cardiac output is likely to increase with a fluid bolus.
Rationale: Although the patient is oliguric and has lactic acidosis, there is not enough information to determine whether renal replacement therapies should be initiated immediately (Option A). If, for instance, his cardiac output improves with a fluid bolus, his lactic acidosis may decrease and urine output increase. A PCWP of 16mm Hg does not reliably discriminate between volume responders and nonresponders (Option B). It is important to remember that the static indices of volume status (e.g., PCWP, CVP, or EF) are of very limited value in defining patients who are volume responsive. Dynamic indices of fluid responsiveness, on the other hand, look at the effect of a physiologic perturbation of venous return and its influence on cardiac output. This may involve respirophasic variation or assessing response to small fluid boluses or passive leg raising, among others. Variation in LVOT VTI >20% with controlled respiration predicts volume responsiveness, although the sensitivity of this finding may be reduced in patients being ventilated with low tidal volumes (<8 mL/kg); however, lower tidal volumes are likely to underestimate volume responsiveness. It is unclear whether epinephrine is better than a combination of norepinephrine and dobutamine (Option C). The CATS trial addressed this question in patients with septic shock and found that the two approaches were largely equivalent, with the exception of a higher incidence of lactic acidosis with epinephrine.
1. Annane D, Vignon P, Renault A, et al. Norepinephrine plus dobutamine versus epinephrine alone for management of septic shock: a randomised trial. Lancet. 2007;370:676-684.
2. Bentzer P, Griesdale DE, Boyd J, MacLean K, Sirounis D, Ayas NT. Will this hemodynamically unstable patient respond to a bolus of intravenous fluid? JAMA 2016;316:1298-1309.
3. De Backer D, Fagnoul D. Intensive care ultrasound: VI. Fluid responsiveness and shock assessment. Ann Am Thorac Soc. 2014 11:129-136.
4. Marik PE, Monnet X, Teboul JL. Hemodynamic parameters to guide fluid therapy. Ann Intensive Care. 2011;1:1.
5. A 47-year-old woman is admitted to the ICU with septic shock and is intubated and mechanically ventilated. She is hypoxemic, with a P:F ratio of 125. A central line has been placed, and she is receiving norepinephrine and vasopressin to support her BP. Her CVP is 10 mm Hg. With POCUS, her maximal aortic velocity variation by pulsed-wave Doppler is 18%, and lung ultrasound shows bilateral consolidations. Which of the following statements is most true regarding her management?
A. A crystalloid bolus of 500 mL over 15 minutes is likely to increase her cardiac output.
B. Diuresis should be initiated to improve her oxygenation.
C. A CVP of 10 mm Hg predicts a lack of fluid responsiveness.
D. CVP readings have very little clinical utility in modern critical care medicine.
5. Correct Answer: A. A crystalloid bolus of 500 mL over 15 minutes is likely to increase her cardiac output.
Rationale: Although many critical care physicians use the CVP to make decisions regarding fluid administration, the CVP is a poor tool for this purpose (Option C). Like measuring changes in VTIs with respiration, changes in maximal aortic velocity >12% can predict fluid responsiveness, that is, an increase in cardiac output by 10-15% in response to a crystalloid bolus. An additional advantage of this technique is that it is quicker to measure the maximal velocity compared to tracing the VTI envelope. Although initiating diuresis (Option B) in patients on vasopressors who are grossly volume overloaded is not unreasonable, in the absence of those indications diuresis is often initiated after patients are no longer vasopressor dependent, as in the Fluid and Catheter Treatment Trial (FACTT). While the CVP is not particularly helpful in identifying patients who are fluid responsive, it can be very helpful in many contexts, including as a measure of RV dysfunction.
1. Cannesson M, Pestel G, Ricks C, Hoeft A, Perel A. Hemodynamic monitoring and management in patients undergoing high risk surgery: a survey among North American and European anesthesiologists. Crit Care. 2011;15:R197.
2. Feissel M, Michard F, Mangin I, Ruyer O, Faller JP, Teboul JL. Respiratory changes in aortic blood velocity as an indicator of fluid responsiveness in ventilated patients with septic shock. Chest. 2001;119:867-873.
3. National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network, Wiedemann HP, Wheeler AP, Bernard GR, et al. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006;354:2564-2575.
6. A 70-year-old woman presents to the Emergency Department with a 2-day history of high fever, flank pain, and dysuria. She has a history of paroxysmal atrial fibrillation (AF) and elevated body mass index (BMI). An electrocardiogram (ECG) shows AF with a rapid ventricular response (HR 134 bpm), and she becomes diaphoretic and hypotensive soon after arrival. POCUS shows normal RV function and moderately depressed LV function. Her lactate is 3.2 mmol/L. A resident prepares to administer a crystalloid bolus of 1 L, but is stopped by the attending physician, who points out that with her reduced LV ejection fraction (LVEF), rapid volume administration may precipitate pulmonary edema and may require intubation. Which of the following maneuvers would most reliably predict a beneficial effect from volume administration?
A. A 25% variation between her maximum and minimum IVC diameter on ultrasound assessment
B. An increase of 15% in her pulse pressure on performing a passive leg raising test
C. A change in pulse pressure of more than 10% with respiration
D. A measured CVP of 5 mm Hg
6. Correct Answer: B. An increase of 15% in her pulse pressure on performing a passive leg raising test.
Rationale: Many of the dynamic indices of fluid responsiveness require stable ventilation with large tidal volumes (>8 mL/kg) to induce a sufficient perturbation in venous return that can reliably modify cardiac output. Similarly, most tests require the patient to be in a sinus rhythm. An important exception is the passive leg raising test, which has been shown to accurately predict fluid responsiveness in a broad range of patient conditions, including assisted or spontaneous ventilation, reduced lung compliance, and arrhythmias.
Ideally, the passive leg raise maneuver should be coupled with a measure of cardiac output or its surrogate (such as the VTI or aortic maximum velocity). If the expertise to measure VTI is unavailable, the pulse pressure variation (>12%) is an acceptable alternative. It is important to keep in mind that while changes in pulse pressure induced by passive leg raising are relatively specific, they are not very sensitive, which is why a metric of cardiac output is preferable.
Both IVC diameter variation (Option A) and pulse pressure changes with respiration (Option C) are not well-validated in spontaneously breathing patients and AF, although at least one study suggests that IVC diameter variation may remain valid in patients with dysrhythmias. While IVC collapse of >40-50% in spontaneously breathing patients is a specific predictor of fluid responsiveness, IVC collapsibility has poor sensitivity in this population, limiting its overall value. In any case, the IVC variation in this example is only 25%. As discussed earlier, CVP is not very useful in predicting volume responsiveness. It is also worth emphasizing that, while the respiratory variation in pulse pressure is not accurate in spontaneously breathing patients or in patients with arrhythmias, pulse pressure variation in response to passive leg raise may be. Note that, since this patient has AF, the change in pulse pressure should be averaged over a few heartbeats to improve accuracy.
1. Bortolotti P, Colling D, Colas V, et al. Respiratory changes of the inferior vena cava diameter predict fluid responsiveness in spontaneously breathing patients with cardiac arrhythmias. Ann Intensive Care. 2018;8(1):79.
2. Monnet X, Bleibtreu A, Ferré A, et al. Passive leg raising and end-expiratory occlusion tests perform better than pulse pressure variation in patients with low respiratory system compliance. Crit Care Med. 2012;40:152-157.
3. Monnet X, Marik P, Teboul JL. Passive leg raising for predicting fluid responsiveness: a systematic review and meta-analysis. Intensive Care Med. 2016;42:1935-1947.
4. Monnet X, Rienzo M, Osman D, et al. Passive leg raising predicts fluid responsiveness in the critically ill. Crit Care Med. 2006;34:1402-1407.
7. A 42-year-old man with severe H1N1 influenza and acute respiratory distress syndrome (ARDS) is intubated and ventilated in the ICU. Lung-protective ventilator settings (tidal volume <8 mL/kg, plateau pressures <30 cm H2O, and appropriate positive end-expiratory pressure [PEEP]) are used. However, to maintain a plateau pressure <30 cm H2O, the tidal volume is reduced to 5 mL/kg ideal body weight, and the respiratory rate (RR) is increased to 24 breaths/min. The patient is sedated and paralyzed to eliminate ventilator-patient dyssynchrony. Assessment of the patient’s fluid responsiveness is carried out by measuring the IVC diameter at end-inspiration and end-expiration, calculating the IVC collapsibility index, which is found to be 0% (Figure 49.1).
Which of the following statements is most accurate regarding intravascular volume management for this patient?
A. An IVC collapsibility index <12% indicates a lack of fluid responsiveness. Therefore, this patient should not get any additional fluid.
B. Colloid-based resuscitation fluids are preferred in patients with ARDS, because increasing the oncotic pressure decreases pulmonary edema.
C. The IVC collapsibility index has not been validated in patients being ventilated with the tidal volumes being used in this case.
D. The IVC collapsibility index corresponds to the CVP and does not predict the likelihood of fluid responsiveness.
7. Correct Answer: C. The IVC collapsibility index has not been validated in patients being ventilated with the tidal volumes being used in this case.
Rationale: The IVC collapsibility index is defined as: [(Maximum IVC diameter – Minimum IVC diameter)/Minimum IVC diameter] or [(Maximum IVC diameter – Minimum IVC diameter)/Mean IVC diameter]. Depending on which method is used, the cutoff values for predicting volume responsiveness are 18% or 12%, respectively. Importantly, both studies were among mechanically ventilated patients with tidal volumes >8 to 10 mL/kg ideal body weight. In patients being ventilated by small tidal volumes, as in this case, the sensitivity of the index is much lower. Therefore, the IVC collapsibility index cannot be used to reliably evaluate volume responsiveness in this patient and is likely to underestimate volume responsiveness. Early studies of IVC diameter variation were conducted in spontaneously breathing patients with the purpose of estimating CVP and are the source of the American Society of Echocardiography’s guidelines for estimating CVP. However, in sedated ventilated patients with large tidal volumes and a lack of spontaneous breathing, the IVC index is a reasonable predictor of fluid responsiveness. There is no convincing evidence that colloid-based resuscitation is superior to crystalloid-based resuscitation in ARDS.
1. Barbier C, Loubières Y, Schmit C, et al. Respiratory changes in inferior vena cava diameter are helpful in predicting fluid responsiveness in ventilated patients. Intensive Care Med. 2004;30:1740-1746.
2. Feissel M, Michard F, Faller JP, Teboul JL. The respiratory variation in inferior vena cava diameter as a guide to fluid therapy. Intensive Care Med. 2004;30(9):1834-1837.
8. A 24-year-old woman presents to the Emergency Department after a motor vehicle collision. She is awake and coherent, but clearly in significant pain, specifically in her left flank area. Her BP is 105/40 mm Hg, and her HR is 95 bpm. A POCUS examination shows an IVC with a maximum diameter of 1.5 cm, which collapses completely on inspiration, and some fluid is seen in the splenorenal space (see Videos 49.3 and 49.4).
Based on this ultrasound examination, which of the following statements about the patient’s volume status and management is most accurate?
A. She is likely to be volume responsive and should get 1 L crystalloid infused rapidly over 15 minutes.
B. She is likely to be volume responsive, but should not get rapid volume resuscitation.
C. She is not likely to be volume responsive and should get maintenance crystalloid infusion at 100 mL/h.
D. She is not likely to be volume responsive and should not get fluid (bolus or maintenance).
8. Correct Answer: B. She is likely to be volume responsive, but should not get rapid volume resuscitation.
Rationale: This patient has a mechanism for intra-abdominal hemorrhage. The fluid in the lienorenal (or splenorenal) space, together with her mechanism of injury, raises the suspicion of splenic injury. Given this predisposition to hypovolemia, an IVC maximal diameter of 1.5 cm is consistent with hypovolemia, and she would likely be volume responsive. However, the principles of damage control resuscitation advise against volume resuscitation, as long as perfusion to critical organs is maintained.
1. Cap AP, Pidcoke HF, Spinella P, et al. Damage control resuscitation. Mil Med. 2018;183(suppl_2):36-43.
2. Schmidt GA, Koenig S, Mayo PH. Shock: ultrasound to guide diagnosis and therapy. Chest. 2012;142(4):1042-1048.
9. Which of the following statements is most true regarding the measurement of superior vena cava (SVC) diameter variation with respiration as an indicator of volume responsiveness in intubated, mechanically ventilated patients?
A. Transesophageal echocardiography (TEE) is required to assess the SVC.
B. It is less specific than pulse pressure variation in predicting volume responsiveness.
C. It can be used effectively in spontaneously breathing patients.
D. All of the above.
9. Correct Answer: A. Transesophageal echocardiography (TEE) is required to assess the SVC.
Rationale: Like the IVC, variations in SVC diameter can also be used to predict volume responsiveness. Although the SVC can be visualized by transthoracic echocardiography (TTE), it is inconsistently visible, and TTE-based SVC evaluation has not been well studied. SVC variation using transesophageal echo (Option A) has been well-validated in mechanically ventilated patients. It is more sensitive and specific than either IVC diameter variation or pulse pressure variation (Option B). Like the IVC collapsibility index, it is not well-validated in patients on assisted breathing modes (Option C).
1. Vignon P, Repessé X, Bégot E, et al. Comparison of echocardiographic indices used to predict fluid responsiveness in ventilated patients. Am J Respir Crit Care Med. 2017;195(8):1022-1032.
10. A 46-year-old African American man with a history of heart failure with reduced EF presents to the Emergency Department with 2 days of fever, dysuria, left flank pain, and foul-smelling urine. He reports dizziness when getting up from his bed that morning. His temperature is 39°C, BP 80/55 mm Hg, HR 110 bpm, RR 28/min, and SpO2 95% on room air. Serum lactate is elevated (5.4 mmol/L). A presumptive diagnosis of pyelonephritis with severe sepsis is made. Given his history of heart failure, a point-of-care echocardiographic examination is performed, and some of the clips are shown ( Videos 49.5 and 49.6).
Based on the patient’s history and ultrasound findings, which of the following statements is most accurate?
A. Given the severely reduced LVEF demonstrated in these images, fluid resuscitation is contraindicated due to the risk of precipitating pulmonary edema.
B. The images demonstrate mildly reduced LV systolic function, and the patient should receive 30 mL/kg crystalloid bolus as recommended by the Surviving Sepsis Guidelines.
C. Severely reduced LV systolic function does not, contraindicate fluid resuscitation, but the volume of fluid used should be carefully determined by repeated assessment of volume responsiveness to minimize the risk of complications.
D. The patient should be started on dobutamine to improve LV systolic function.
10. Correct Answer: C. Severely reduced LV systolic function does not, contraindicate fluid resuscitation, but the volume of fluid used should be carefully determined by repeated assessment of volume responsiveness to minimize the risk of complications.
Rationale: This patient presents with signs and symptoms consistent with the current definition of sepsis, but also has a documented history of heart failure with a reduced EF. POCUS examination shows severely decreased LVEF in apical three-chamber and apical two-chamber views ( Videos 49.5 and 49.6).
However, poor LV systolic function or high filling pressures (central venous or pulmonary capillary wedge) do not preclude fluid administration (Option A). Nonetheless, the tolerance of patients with poor LV function for large volumes of fluid may be limited. The best response would be to administer relatively small fluid boluses (250-500 mL) and reassess for evidence of fluid responsiveness (Option C). The videos show severely reduced LV systolic function, so Option B is incorrect. There is not enough data to determine whether this patient will need an inotrope such as dobutamine, certainly not as the next step in management (Option D).
1. Singer M, Deutschman CS, Seymour CW, et al. The third international consensus definitions for sepsis and septic shock (sepsis 3). JAMA. 2016;315(8):801-810.
2. Vincent JL, Weil MH. Fluid challenge revisited. Crit Care Med. 2006;34(5):1333-1337.
11. A patient with severe ARDS is paralyzed and mechanically ventilated with tidal volumes of 6 mL/kg ideal body weight. The patient’s lung compliance is poor (19 mL/cm H2O), and P:F ratio is 95 mm Hg. Bedside echocardiography is performed to measure the VTI from an apical five-chamber view. While performing an end-expiratory occlusion test (EEOT), the VTI is noted to increase by 15%. Which of the following statements is most true when considering the EEOT?
A. Poor lung compliance makes the EEOT invalid in this population.
B. End-expiratory occlusion is a static maneuver and therefore not very useful in predicting fluid responsiveness.
C. An EEOT should be carried out for 5 seconds to determine fluid responsiveness.
D. Combining EEOT with an end-inspiratory occlusion test (EIOT) can improve the sensitivity of the technique when using echocardiography.
11. Correct Answer: D. Combining EEOT with an end-inspiratory occlusion test (EIOT) can improve the sensitivity of the technique when using echocardiography.
Rationale: The EEOT is based on the principle that a sustained (>15 seconds) interruption in positive pressure ventilation can increase venous return and consequently increase cardiac output in volume-responsive patients. Conversely, in volume-replete patients, there is a minimal difference in venous return with interruption of ventilation, and therefore no change in cardiac output. In practice, EEOT can be performed with a prolonged expiratory hold in sedated and paralyzed patients. The EEOT has been shown to be useful in patients with poor lung compliance, unlike pulse pressure variation (Option A). It is not a static maneuver, as it relies on altering venous return in response to intrathoracic pressure changes (Option B). Combining EEOT with EIOT allows the incorporation of the decrease in VTI with a sustained inspiratory hold. EIOT is maintained for 15 seconds (as with EEOT), with 1 minute between measurements. If the total change in VTI (increase with EEOT + decrease with EIOT) is >13%, the patient is likely to be fluid responsive (see Figure 49.8). While the test can be carried out in patients who have some spontaneous respiratory activity, the patient should be able to tolerate a 15-second breath-hold without taking a spontaneous breath. In practice, this limits its use in spontaneously breathing patients.
Figure 49.8 Change in velocity-time integral (VTI) at baseline, during an end-expiratory hold, and after end-inspiratory occlusion.
1. Jozwiak M, Depret F, Teboul JL, et al. Predicting fluid responsiveness in critically ill patients by using combined end-expiratory and end-inspiratory occlusions with echocardiography. Crit Care Med. 2017;45:e1131-e1138.
2. Monnet X, Osman D, Ridel C, Lamia B, Richard C, Teboul JL. Predicting volume responsiveness by using the end-expiratory occlusion in mechanically ventilated intensive care unit patients. Crit Care Med. 2009;37:951-956.
12. A clinician is performing point-of-care echocardiography on an intubated, ventilated patient with septic shock. The patient is being ventilated on volume-controlled ventilation using 6 mL/kg ideal body weight, but is relatively lightly sedated and “overbreathing” the ventilator. The patient is on 10 µg/min of norepinephrine but has warm extremities with bounding pulses. The clinician is trying to determine whether the patient should be given a fluid bolus. Which of the following findings would be most reliable to predict fluid responsiveness based on the current literature?
A. The IVC diameter at end-inspiration is 1.8 cm, and at end-expiration is 1.3 cm.
B. The LVEF is 65%.
C. The VTI at the LVOT increases by 20% with a passive leg raise.
D. There is >10% variation in the maximal LVOT velocity with respiration.
12. Correct Answer: C. The VTI at the LVOT increases by 20% with a passive leg raise.
Rationale: The passive leg raise test has proven to be useful in identifying fluid responsiveness in patients under a diverse set of conditions. To be most effective, the passive leg raise should be coupled with measurement of cardiac output. One of the ways to do this is to acquire an LVOT VTI by echocardiography before and after the maneuver. It should be noted that although this is a well-validated method, it requires advanced echocardiographic skills. While the IVC distensibility index is approximately 33% for this patient, the IVC index has not been validated in patients on assisted (but not passive) ventilation. Similarly, changes in LVOT maximal velocity have not been shown to be predictive in patients on assisted ventilation. The EF can appear normal in patients with severe diastolic dysfunction and low stroke volume, as well as with severe valvular regurgitant lesions, and adds little value in predicting fluid responsiveness.
1. Brun C, Zieleskiewicz L, Textoris J, et al. Prediction of fluid responsiveness in severe preeclamptic patients with oliguria. Intensive Care Med. 2013;39(4):593-600.
13. Which of the following statements is most true regarding the least significant change (LSC) that can be reliably measured by echocardiography when measuring VTI changes under dynamic conditions, such as with mechanical ventilation?
A. The LSC in measuring the VTI in two sequential examinations is the same whether a single operator performs both examinations or the examinations are performed by different operators.
B. The LSC in the VTI that can be reliably measured by a single operator is about 11%.
C. The LSC in the VTI that can be measured by a single observer is lower in mechanically ventilated patients than in spontaneously breathing patients.
D. In most clinical situations, a change in VTI of 5% can be reliably detected by echocardiography.
13. Correct Answer: B. The LSC in the VTI that can be reliably measured by a single operator is about 11%.
Rationale: For most dynamic measures of fluid responsiveness, measuring cardiac output or its surrogates (such as VTI) is more reliable than measuring the pulse pressure variation. Since the echocardiographic assessments of VTI are commonly used to assess fluid responsiveness, it is important to assess the accuracy, precision, and the LSC that can be reliably detected. There is a paucity of studies that address this question; however, recent work by Jozwiak, et al. has provided some guidance. The authors found that sequential measurements of VTI were able to detect a smaller change in the VTI when the examinations were performed by the same operator than when different operators performed the examinations (Option A is incorrect). The median LSC that can be detected by a single examiner was found to be 11% (Option B is correct). Interestingly, the LSC was similar for both spontaneously breathing and mechanically ventilated patients (Option C is incorrect). Finally, given that the LSC in sequential VTI measurements is around 11%, smaller changes are unlikely to be reliably detected by echocardiography (Option D is incorrect).
1. Jozwiak M, Mercado P, Teboul JL, et al. What is the lowest change in cardiac output that transthoracic echocardiography can detect? Crit Care. 2019;23(1):116.
2. Monnet X, Marik P, Teboul JL. Passive leg raising for predicting fluid responsiveness: a systematic review and meta-analysis. Intensive Care Med. 2016;42(12):1935-1947.
14. When considering fluid management questions, POCUS is typically used to assess fluid responsiveness. However, POCUS can also be helpful in identifying patients who have systemic venous congestion and would benefit from fluid removal. One such index that can be clinically useful is the portal venous pulsatility index (PVPI). Which of the following statements about the PVPI is most true?
A. Since IVC measurements provide a reliable estimation of right atrial pressure (RAP) in mechanically ventilated patients, there is no need to assess PVPI if a reliable RAP estimate can be obtained.
B. The portal vein is typically assessed from the subxiphoid view using a cardiac (phased-array) probe.
C. The portal vein is only pulsatile in patients with severe cirrhosis and portal hypertension.
D. The portal vein is typically nonpulsatile—a PVPI >50% is a useful indicator of systemic congestion and RV dysfunction.
14. Correct Answer: D. The portal vein is typically nonpulsatile—a PVPI >50% is a useful indicator of systemic congestion and RV dysfunction.
Rationale: Systemic congestion can have detrimental effects on organ function, inducing acute kidney injury and congestive hepatopathy. In ventilated patients, the value of IVC measurements in inferring CVP measurements can be poor (Option A is incorrect). Assessing portal venous pulsatility can be a valuable technique for detecting systemic venous congestion and RV dysfunction. The portal vein can be imaged with a 2.5 to 5 MHz transducer (cardiac or abdominal) at the posterior axillary line, allowing the IVC, the hepatic vein, and the portal vein to be visualized (Option B is incorrect). The walls of the portal vein are relatively more hyperechoic than the walls of the hepatic vein. Blood flow in the portal vein is normally nonpulsatile, and significant pulsatility (a PVPI >50%) indicates RV dysfunction or systemic congestion (Option D). While other causes of portal hypertension (cirrhosis, portal venous thrombosis) can also cause a high PVPI, cardiac dysfunction (e.g., tricuspid regurgitation) can also be a cause (Option C is incorrect). (See Figure 49.9.)
1. Beaubien-Souligny W, Bouchard J, Desjardins G, et al. Extracardiac signs of fluid overload in the critically ill cardiac patient: a focused evaluation using bedside ultrasound. Can J Cardiol. 2017;33(1):88-100.
2. Denault AY, Azzam MA, Beaubien-Souligny W. Imaging portal venous flow to aid assessment of right ventricular dysfunction. Can J Anaesth. 2018;65(11):1260-1261.
3. Jue J, Chung W, Schiller NB. Does inferior vena cava size predict right atrial pressures in patients receiving mechanical ventilation? J Am Soc Echocardiogr. 1992;5(6):613-619.
4. Styczynski G, Milewska A, Marczewska M, et al. Echocardiographic correlates of abnormal liver tests in patients with exacerbation of chronic heart failure. J Am Soc Echocardiogr. 2016;29(2):132-139.
15. A 64-year-old man with severe ARDS (P:F ratio 92 mm Hg) is intubated, sedated, and paralyzed, mechanically ventilated with volume control ventilation. To reduce plateau and driving pressure, his tidal volume has been reduced to 5 mL/kg ideal body weight. In order to assess whether he is fluid responsive, a point-of-care echocardiogram is performed to measure the changes in VTI with respiration. The percent change in the VTI is noted to be 6%. Which of the following statements is most true?
A. Since the patient’s VTI variation is <10%, he is unlikely to be fluid responsive.
B. No technique for evaluating fluid responsiveness has been shown to be reliable in patients being ventilated with <6 mL/kg ideal body weight.
C. The combination of low tidal volumes and poor lung compliance in this patient makes VTI variation with respiration relatively unpredictable.
D. None of the above.
15. Correct Answer: C. The combination of low tidal volumes and poor lung compliance in this patient makes VTI variation with respiration relatively unpredictable.
Rationale: This patient has severe ARDS with low lung compliance, reflected in the need to reduce his tidal volumes to 5 mL/kg to keep plateau pressure and driving pressure within recommended limits. In such patients, airway pressure changes may not be reliably transmitted from the lung parenchyma to the extrapulmonary intrathoracic space, and therefore have unpredictable effects on preload. Because of this, the effects of changes in cardiac output, VTI, or pulse pressure variation with respiration can be unpredictable (Option C is correct). Therefore, the lack of significant VTI variation with respiration is not sufficient to define this patient as being fluid unresponsive (Option A is incorrect). It is important to recognize that the test retains its specificity—a large VTI variation would imply volume responsiveness in the setting of poorly compliant lungs/small tidal volumes. A number of dynamic indices of fluid responsiveness lose sensitivity in the setting of low-tidal-volume ventilation/poor lung compliance. Those which do not rely on changes in intrathoracic pressure, such as passive leg raise, do not. Measuring the change in VTI in response to a passive leg raise maneuver is a good technique to assess fluid responsiveness in this situation (Option B is incorrect).
1. Charron C, Fessenmeyer C, Cosson C, et al. The influence of tidal volume on the dynamic variables of fluid responsiveness in critically ill patients. Anesth Analg. 2006;102(5):1511-1517.
2. De Backer D, Fagnoul D. Intensive care ultrasound: VI. Fluid responsiveness and shock assessment. Ann Am Thorac Soc. 2014 11:129-136.
3. Monnet X, Marik PE, Teboul JL. Prediction of fluid responsiveness: an update. Ann Intensive Care. 2016;6(1):111.
4. Vignon P, Repessé X, Bégot E, et al. Comparison of echocardiographic indices used to predict fluid responsiveness in ventilated patients. Am J Respir Crit Care Med. 2017;195(8):1022-1032.
16. The following statements regarding the use of esophageal Doppler probes for goal-directed resuscitation in the operating room are true except:
A. Studies suggest that the use of esophageal Doppler probes during major surgery to guide resuscitation can reduce the incidence of postoperative complications.
B. An increase in the stroke distance in the esophageal Doppler signal after a fluid challenge suggests improving cardiac output.
C. The esophageal Doppler signal detects flow in the ascending aorta and therefore reflects the total LV stroke volume.
D. Esophageal Doppler signals can be used to diagnose aortic regurgitation and pericardial tamponade.
16. Correct Answer: C. The esophageal Doppler signal detects flow in the ascending aorta and therefore reflects the total LV stroke volume.
Rationale: The esophageal Doppler probe is placed transorally into the esophagus to a depth of about 35 to 40 cm, capturing the flow signal from the descending thoracic aorta (Option C is false, and therefore the correct answer). Therefore, only a part of the LV stroke volume is accessible, and manufacturers use algorithms to extrapolate that value into the cardiac output. The use of these probes in goal-directed resuscitation during major surgery has been found to reduce the incidence of postoperative complications in some studies (Option A). The stroke distance on the Doppler signal is directly proportional to the stroke volume (Option B), and changes in the morphology of the Doppler signal can be used to detect aortic regurgitation and cardiac tamponade (Option D).
1. Singer M. Oesophageal Doppler. Curr Opin Crit Care. 2009;15(3):244-248.
2. Wakeling HG, McFall MR, Jenkins CS, et al. Intraoperative oesophageal Doppler guided fluid management shortens postoperative hospital stay after major bowel surgery. Br J Anaesth. 2005;95:634-642.
17. A 67-year-old woman with a history of heart failure with reduced EF and elevated BMI (42 kg/m2) is admitted to an ICU with acute decompensated heart failure. Her temperature is 36°C, HR 95 bpm, BP 105/75 mm Hg, RR 105/min, and SpO2 84% on room air. On physical examination, she is noted to have cool extremities with 2+ pitting edema and crackles at both lung bases. POCUS shows severely depressed LV function, mildly depressed RV function, and pathologic “B-lines” in bilateral anterior lung fields. She is intubated for increasing hypoxemia and started on an epinephrine infusion to support her cardiac output and BP. Renal replacement therapy with CVVH is initiated for severe volume overload and diuretic resistance. Which of the following statements is most true regarding the assessment of her volume status with ultrasound?
A. Volume removal will increase her stroke volume, by reducing LV size and bringing the heart to a more physiologic position on the Starling curve.
B. The number and severity of B-lines will decrease as fluid is removed.
C. Chest X-ray is more sensitive than lung ultrasound when assessing extravascular lung water (EVLW).
D. B-lines are specific for the presence of EVLW.
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