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Middle-Aged Woman With Shock FREE TO VIEW

Siddharth Dugar, MD; Phani Kantamneni, MD; Charles R. Lane, MD; Ajit Moghekar, MD
Author and Funding Information

CORRESPONDENCE TO: Ajit Moghekar, MD, Deptartment of Critical Care, Respiratory Institute, Cleveland Clinic, 9500 Euclid Ave, L2, Cleveland, OH 44195


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;149(2):e45-e47. doi:10.1016/j.chest.2015.08.025
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Published online

A middle-aged woman with a medical history of COPD on 3 L of home oxygen, idiopathic thrombocytopenic purpura status postsplenectomy, and hypothyroidism presented to the ED with fever and change in mental status. On presentation, she was febrile (temperature 39.6°C), tachycardic (heart rate, 130-140 beats/min), and hypotensive (blood pressure, 89/57 mm Hg). Her respiratory rate was 24 to 26 breaths/min and oxygen saturation of 84% on room air, which improved to 95% on 40% Venti mask. Physical examination revealed a middle-aged woman who was unresponsive, moaning, and grunting. She had labored breathing with bilateral crackles. Cardiac examination revealed tachycardia with a collapsed jugular vein.

Laboratory evaluation on admission revealed leukocytosis (WBC count, 19,840 cells/μL; 99% neutrophils), anemia (hemoglobin, 9.2 g/dL), and a serum lactate level of 6.5 mmol/L and central venous oxygen saturation of 59%. Troponin T levels were < 0.010 ng/mL and remained negative throughout the patient’s stay. She was started on vancomycin, ceftriaxone, and ampicillin for suspected meningitis and was intubated for airway protection given her mental status. The patient received antibiotics and 1 L of crystalloid in the ED, but she continued to remain hypotensive and was started on norepinephrine.

A point-of-care echocardiogram was performed on admission to the ICU, which revealed a hyperdynamic left ventricle. There was a small pericardial effusion anteriorly, but no right ventricular diastolic collapse or right atrial systolic collapse was present. The inferior vena cava was 1.4 cm and collapsed completely with inspiration (Video 1). The cause of her shock was assumed to be hypovolemia and sepsis. She was given 3 L of crystalloid solution. Her vital signs and lactate levels normalized in 10 h.

On day 2, the patient had increasing vasopressor requirements; her lactate level increased to 4.9 mmol/L and central venous oxygen saturation dropped to 46%. A repeat beside echocardiogram was performed (Video 1).

Question: Based on the clinical course and echocardiographic images, what would be the next view you would like to obtain?

Answer: The next view to obtain in a patient with low cardiac output and elevated lactate level is an apical five-chamber or apical three-chamber view to determine the left ventricular outflow tract (LVOT) velocity time integral (VTI). The LVOT VTI is used as a surrogate for stroke volume to guide management of shock with inotropic medication and/or fluids.

The second echo in Video 1 demonstrates a hypocontractile left ventricle. The left ventricular systolic function is globally reduced, and the inferior vena cava is dilated with <50% collapsibility. There is sluggish flow through the inferior vena cava, suggestive of low flow state.

Echocardiograms are commonly used in the ICU as a diagnostic tool to rule out life-threatening conditions and ascertain the source of hemodynamic instability. With time, the sphere of the point-of-care echocardiogram has expanded to the field of hemodynamic monitoring., Repeat echocardiogram with Doppler indices can be used to noninvasively guide our management of patients in shock by measuring stroke volume and volume status. In 2015, the American Society of Echocardiography published guidelines on using echocardiography as a method to monitor therapeutic interventions.

In the absence of any significant valvular abnormality, stroke volume can be calculated by measuring the cross-sectional area (CSA) of the LVOT and the velocity of the blood flowing through the LVOT.

The aortic annulus is circular with little variability during systole and hence is an appropriate site for measuring VTI. The LVOT diameter is obtained in the parasternal long-axis view by measuring the LVOT at mid-systole just below the aortic annulus toward the left ventricle. It is measured from the junction of the aortic leaflets with the septal endocardium to the junction of the leaflet with the mitral valve posteriorly, using inner edge to inner edge. CSA is calculated by using the formula CSA = πr2 (r is the radius of LVOT in centimeters). As noticed, any inaccuracy in measurement of LVOT diameter is “squared”; appropriate care should therefore be exercised when measuring it. Using a zoomed-in view of LVOT in the parasternal long-axis for a more exact reading may help. The CSA is expressed in centimeters squared. For ensuing measurement of stroke volume, only VTI is usually measured because CSA fluctuates little over time.

The LVOT VTI is measured in the apical five-chamber view or the apical three-chamber view using a pulsed wave Doppler with the sample volume placed 5 mm proximal to the aortic annulus toward the left ventricle. The LVOT VTI is the area under the curve and is expressed in centimeters. The stroke volume is CSA * LVOT VTI and is expressed in cubic centimeters (ie, cm3 or cc).

An average of three to five VTI measurements are taken for calculation of stroke volume. For an irregular rhythm (eg, atrial fibrillation), an average of five to 10 LVOT-VTI readings is recommended to accurately estimate the stroke volume. Basic knowledge of Doppler physics is essential for accurate measurement of LVOT-VTI. This skill can be easily obtained by the intensivist and most bedside ultrasound machines offer doppler ultrasound to measure the VTI.

In the current case, the clinical course, in addition to a globally reduced left ventricular contraction, was pointing toward sepsis-induced cardiomyopathy being the driving factor for her clinical worsening. The point-of-care echocardiogram showed an aortic diameter of 2.16 cm (Video 2) and an LVOT VTI of 8.8 cm (Video 2). The stroke volume and cardiac output were calculated to be 32.3 cc and 2.3 L/min, respectively. The patient was started on dobutamine, and a point-of-care echocardiogram was repeated to determine its impact on stroke volume. On 5 μg/min, the LVOT VTI and stroke volume were augmented to 19 cm and 69.8 cc. We titrated the dobutamine drip to maintain LVOT VTI > 18 cc, which was achieved with 5 μg/min of dobutamine. Her lactate levels and vital signs normalized in 24 h. A repeat echocardiogram conducted when the patient was not taking any vasoactive/inotropic medication for 24 h showed complete resolution of her left ventricular dysfunction, affirming the diagnosis of septic cardiomyopathy.

The scope of echocardiogram use in critical care has transcended to noninvasive hemodynamic monitoring. Point-of-care echocardiograms can be used to serially measure hemodynamic parameters, assess response to fluids and medications, and titrate medications accordingly. In the current case, with repeated measures of the VTI, we were able to titrate the dose of dobutamine to maintain an adequate stroke volume, as evidenced by the normalization of central venous oxygen saturation and lactate levels.

  • 1.

    Conducting a point-of-care echocardiogram is an easily obtainable skill and is becoming a standard practice for the intensivist.

  • 2.

    The stroke volume can be measured noninvasively by calculating the LVOT VTI and CSA of LVOT.

  • 3.

    The echocardiogram can be used as a primary tool to titrate fluids, diuretic agents, or inotropic agents based on various hemodynamic parameters.

  • 4.

    Sepsis is a dynamic process; the echocardiogram should be repeated to answer different questions at different stages of the disease process.

Financial/nonfinancial disclosures: None declared.

Other contributions:CHEST worked with the authors to ensure that the Journal policies on patient consent to report information were met.

Additional information: To analyze this case with the videos, see the online version of this article.

Mandeville J.C. .Colebourn C.L. . Can transthoracic echocardiography be used to predict fluid responsiveness in the critically ill patient? A systematic review. Crit Care Research Prac. 2012;2012:513480- [PubMed]journal
 
Porter R.T. .Shillcutt S.K. .Adams M.S. .et al Guidelines for the use of echocardiography as a monitor for therapeutic intervention in adults: a report from the American Society of Echocardiography. J Am Soc Echocardiogr. 2015;28:40-56 [PubMed]journal. [CrossRef] [PubMed]
 
Chimot L. .Legrand M. .Canet E. .Lemiale V. .Azoulay E. . Echocardiography in hemodynamic monitoring. Chest. 2010;137:501-502 [PubMed]journal. [CrossRef] [PubMed]
 
Quinones M.A. .Otto C.M. .Stoddard M. .et al Recommendations for quantification of Doppler echocardiography: a report from the Doppler quantification task force of the nomenclature and standard committee of the American Society of Echocardiography. J Am Soc Echocardiogr. 2002;15:167-184 [PubMed]journal. [CrossRef] [PubMed]
 
Narasimhan M. .Koenig S.J. .Mayo P.H. . Advanced echocardiography for the critical care physician: part 2. Chest. 2014;145:135-142 [PubMed]journal. [CrossRef] [PubMed]
 
Ristow B. .Na B. .Ali S. .Whooley M.A. .Shiller N.B. . Left ventricular outflow tract and pulmonary artery stroke distances independently predict heart failure hospitalization and mortality: the Heart and Soul Study. J Am Soc Echocardiogr. 2011;24:565-572 [PubMed]journal. [CrossRef] [PubMed]
 
Vieillard-Baron A. . Septic cardiomyopathy. Ann Intensive Care. 2011;1:6- [PubMed]journal. [CrossRef] [PubMed]
 

Figures

Tables

References

Mandeville J.C. .Colebourn C.L. . Can transthoracic echocardiography be used to predict fluid responsiveness in the critically ill patient? A systematic review. Crit Care Research Prac. 2012;2012:513480- [PubMed]journal
 
Porter R.T. .Shillcutt S.K. .Adams M.S. .et al Guidelines for the use of echocardiography as a monitor for therapeutic intervention in adults: a report from the American Society of Echocardiography. J Am Soc Echocardiogr. 2015;28:40-56 [PubMed]journal. [CrossRef] [PubMed]
 
Chimot L. .Legrand M. .Canet E. .Lemiale V. .Azoulay E. . Echocardiography in hemodynamic monitoring. Chest. 2010;137:501-502 [PubMed]journal. [CrossRef] [PubMed]
 
Quinones M.A. .Otto C.M. .Stoddard M. .et al Recommendations for quantification of Doppler echocardiography: a report from the Doppler quantification task force of the nomenclature and standard committee of the American Society of Echocardiography. J Am Soc Echocardiogr. 2002;15:167-184 [PubMed]journal. [CrossRef] [PubMed]
 
Narasimhan M. .Koenig S.J. .Mayo P.H. . Advanced echocardiography for the critical care physician: part 2. Chest. 2014;145:135-142 [PubMed]journal. [CrossRef] [PubMed]
 
Ristow B. .Na B. .Ali S. .Whooley M.A. .Shiller N.B. . Left ventricular outflow tract and pulmonary artery stroke distances independently predict heart failure hospitalization and mortality: the Heart and Soul Study. J Am Soc Echocardiogr. 2011;24:565-572 [PubMed]journal. [CrossRef] [PubMed]
 
Vieillard-Baron A. . Septic cardiomyopathy. Ann Intensive Care. 2011;1:6- [PubMed]journal. [CrossRef] [PubMed]
 
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