ULTRASOUND OF INFERIOR VENA CAVA OBJECTIVES Describe indications

ULTRASOUND OF INFERIOR VENA CAVA

OBJECTIVES Describe indications for using ultrasound at the bedside to image the inferior vena cava. Describe how to performing bedside ultrasound of the inferior vena cava. Use the findings on ultrasound to guide assessment of intravascular volume status. Generate group discussion regarding the potential value of learning this procedure for patient management

CASE 46 M was admitted with alcoholic hepatitis and newly diagnosed cirrhosis with ascites. On exam he had flat JVD in supine position, tense abdominal distension, and moderate leg edema to the knees. He was started on a 28 day Trental protocol Hospital Course Day 1 -9 - 3 paracenteses; - removal of 11 liters of ascitic fluid. Day 10 - JVD flat in supine position - Abdomen still distended but not tense - moderate leg edema - Na = 136, Cr = 1. 0, BUN = 11 - furosemide started at 20 mg QD - spironolactone started at 50 mg QD.

CASE Day 12 Day 19 - JVD flat in supine position - persistent leg edema - apparent increase in abdominal girth on exam - Na = 134, Cr = 0. 7, BUN = 12 - furosemide increased to 40 mg QD - JVD flat in supine position - persistent leg edema - abdominal girth same to slightly decreased - Na = 136, Cr = 0. 8, BUN = 12 - furosemide increased to 80 mg QD - spironolactone increased to 200 mg QD

CASE Day 21 Day 24 - JVD flat in supine position - leg edema the same - Abdominal girth the same - Na = 130, Cr = 0. 9, BUN = 10 - JVD flat in the supine position - leg edema the same - Abdominal girth the same to slightly increased - Na = 127, Cr = 0. 7, BUN = 13, Urine Na < 10 Daily weights and Input/Output measures were collected sporadically and could not be assessed for any trends.

CLASSIC HYPONATREMIA Hypovolemic UNa Euvolemic Hypervolemic UOsm > SOsm UNa > 40 UNa < 10 > 20 YES NO < 10 > 20 Volume Depletion Mineralcorticoid Deficiency SIADH OTHER Cirrhosis Nephrosis CHF CKD Volume Replacement Fluid Restriction plus Diuretics

QUESTION What type of hyponatremia does this patient have and how should it be managed? A. Hypovolemic hyponatremia stop diuretics; begin normal saline infusion; liberalize po fluid intake; monitor Na over the course of the next several days; if Na does not improve or worsens, entertain hypervolemic hyponatremia as the cause A. Hypervolemic hyponatremia increase the diuretics and tighten the fluid restriction; monitor Na over the course of the next several days; if Na does not improve or worsens, entertain hypovolemic hyponatremia as the cause. A. Not sure consult nephrology for an opinion about the hyponatremia

INDICATIONS IVC Ultrasound Spontaneously Breathing Volume Status / CVP Mechanical Ventilation Fluid Responsiveness

INDICATIONS Assessing Intravascular Volume Status / CVP VOLUME DEPLETED STATES - Hyponatremia - Acute Kidney Injury (? Prerenal) - Diuretic therapy - Sepsis VOLUME OVERLOAD STATES -Hyponatremia - Heart Failure -Cirrhosis with ascites - Anasarca

INDICATIONS Assessing Fluid Responsiveness in Shock - IVC diameter does not correlate with right atrial pressure in patients who are intubated with shock - Measuring the variation in IVC diameter in these situations can help determine whether the patient’s blood pressure will respond to fluids or whether inotropic support (i. e. dobutamine) will be needed

Anatomy The inferior vena cava returns blood from the body to the right atrium Formed by the convergence of the illiac veins Retroperitoneal Right of the aorta Normal size <2. 5 cm Varies w respiration

Respiratory variation Expands w/ expiration Contracts w/ inspiration Due to changing intrathoracic pressures.

Respiratory Variation Figure 2: Physiological respiratory variations in IVC diameter in a healthy volunteer breathing quietly. : From: http: //www. pifo. uvsq. fr/hebergement/webrea/index. php? option=com_content&task=view&id=36&Itemid=93 IVC diameter decreases on each inspiration. http: //www. criticalecho. com/content/tutorial-4 -volume-status-and-preload-responsiveness-assessment

Measuring the IVC Diameter Measure IVC 2 cm distal to right atrium

Inspiratory (Minimal) IVC Diameter

Maximum (Expiratory) IVC Diameter

M-Mode IVC Diameters

CAVAL INDEX (CI) maximum (expiratory) diameter CI minimal (inspiratory) diameter = maximum (expiratory) diameter

CAVAL INDEX (CI) 0% Volume Overload 100% Volume Depletion

IVC v CVP Correlation Between IVC Diameter Plus CI and CVP IVC Max Diameter (cm) CI CVP (mm. Hg) < 1. 5 100% (total collapse) 0 -5 1. 5 -2. 5 > 50% 6 -10 1. 5 -2. 5 < 50% 11 -15 > 2. 5 < 50% 16 -20 > 2. 5 0% (no collapse) >20

M-Mode Volume Depletion

M-Mode Volume Overload

IVC v CVP Correlation Between IVC Diameter Plus CI and CVP IVC Max Diameter (cm) CI CVP (mm. Hg) < 1. 5 100% (total collapse) 0 -5 1. 5 -2. 5 > 50% 6 -10 1. 5 -2. 5 < 50% 11 -15 > 2. 5 < 50% 16 -20 > 2. 5 0% (no collapse) >20

PROCEDURE Positioning 1 Supine 2 Degree of head elevation has not been shown to make a significant difference in measurements

PROCEDURE Probe Selection 1 Low frequency 2 -5 MHz 2 Curvalinear probe

PROCEDURE Approach #1 – Xiphoid View

PROCEDURE Landmarks Aproach #1 – Xiphoid View 1 Most common approach 2 Place probe longitudinally just below the xiphoid process with the probe marker to the patient’s head 3 Look for IVC going into right atrium – may need to move probe 1 -2 cm to patient’s right and then tilt it slightly towards the heart

IVC Longitudinal

PROCEDURE Approach #2 – Anterior Mid-Axillary View

PROCEDURE Landmarks Aproach #2 – Anterior Mid-Axillary View 1 Place probe longitudinally in right anterior mid-axillary line with marker towards the head 2 Look for IVC running longitudinally adjacent to liver crossing the diaphragm. 3 Track superiorly until it enters right atrium confirming that it is the IVC and not the aorta.

IVC Anterior Mid-Axillary View

PEARLS Bowel Gas 1 May impede visualization in the xiphoid view 2 Gentle graded pressure may help move bowel out of way 3 Don’t press too hard or will collapse IVC causing false measurements 4 Consider anterior mid-axillary view

PEARLS Plethoric (dilated/sluggish) IVC 1 2 3 4 Volume overload Cardiac tamponade Mitral regurgitation Aortic stenosis

PEARLS Mechanical Ventilation 1 Causes reversal of IVC changes with respiration 2 Maximum diameter with inspiration, minimum diameter with expiration

PEARLS IVC v Aorta IVC Thick, echogenic walls Pulsatile High flow velocity Not compressable No respiratory variation Above vertebral bodies Thin walls Usually not pulsatile Low flow velocity Compressable Respiratory variation Right of vertebral bodies

Aorta – Longitudinal View

Sono. Site 180 Plus

Sono. Site 180 Plus

Sono. Site 180 Plus Changing and Inserting the Transducer

Sono. Site 180 Plus Insert the transducer Twist lock counterclockwise

Sono. Site 180 Plus Fold lock down

Sono. Site 180 Plus Ready to power-up machine

Sono. Site 180 Plus Power Button

Sono. Site 180 Plus

Sono. Site 180 Plus

Sono. Site 180 Plus

Sono. Site 180 Plus Wrong Transducer is Connected Correct Transducer Menu -GYN -OB -Abdominal

Sono. Site 180 Plus 2 D View (default) M-Mode

Sono. Site 180 Plus GAIN Changes the contrast on the screen

Sono. Site 180 Plus

Sono. Site 180 Plus

CASE An IVC Ultrasound was performed at the bedside. Maximum IVC diameter during expiration = 1. 10 cm. The Minimum IVC diameter during inspiration = 0 cm. Caval Index = 100% (total collapse)

CASE Correlation Between IVC Diameter Plus CI and CVP IVC Max Diameter (cm) CI CVP (mm. Hg) < 1. 5 100% (total collapse) 0 -5 1. 5 -2. 5 > 50% 6 -10 1. 5 -2. 5 < 50% 11 -15 > 2. 5 < 50% 16 -20 > 2. 5 0% (no collapse) >20 Interpretation: Mixed hyponatremia (intravascular volume depletion plus free water excess from cirrhosis)

CASE Treatment: - one liter of normal saline IV to expand intravascular volume - reduced free water oral intake from 1500 cc to 1000 cc/d - Continued current diuretic dosing to remove free water Result: In 3 days, the patient’s Na progressively increased to 136

REFERENCES -De Lorenzo RA, Morris MJ, William JB, et al. Does a simple bedside sonographic measurement of the inferior vena cava correlate to central venous pressure? J. Emer. Med. 2011; 42(4); 429 -436. -Kosiak W, Swieton D, Piskunowicz M. Sonographic inferior vena cava/aorta diameter index, a new approach to the body fluid status assessment in children and young adults in emergency ultrasound preliminary study. Acad. J. Emerg. Med. 2008; 26: 320 -5 -Blehar DJ, Dickman E, Gaspari R. Identification of congestive heart failure via respiratory variation of inferior vena cava diameter. Am. J. Emerg. Med. 2009; 27: 71 -5. -Chen L, Santucci KA, Kim Y. Use of ultrasound measurement of the inferior vena cava diameter as an objective tool in the assessment of children with clinical dehydration. Acad. Emerg. Med. 2007: 14: 841 -5. -Feissel M, Michard F, Faller JP, et al. The respiratory variation in inferior vena cava diameter as a guide to fluid therapy. Intensive Care Med. 2004; 30: 1834 -7. -Fields JM, Lee PA, Jenq KY, et al. The interrater reliability of inferior vena cava ultrasound by bedside clinician sonographers in emergency department patients. Acad. Emerg. Med. 2011; 18: 98 -101. -Kircher BJ, Himelman RB, Schiller NB. Noninvasive estimation of right atrial pressure from the inspiratory collapse of the inferior vena cava. Am J. Cardiol. 1990; 66: 493 -6. -Randazzo MR, Snoey ER, Levitt MA, et al. Accuracy of emergency physician assessment of left ventricular ejection fraction and central venous pressure using echocardiography. Acad. Emerg. Med. 2003; 10: 973 -7. -ACEP Policy Statement on Emergency Ultrasound Guidelines. Ann. Emerg. Med. 2009; 53: 550 -70 -Nagdev AD, Merchant RC, Tirado-Gonzalez A, et al. Emergency department bedside ultrasonographic measurement of the caval index for noninvasive determination of low central venous pressure. Ann. Emerg. Med. 2010; 55: 290 -5.

DISCUSSION