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 50mg QD.
CASE
Day 12
- 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 40mg QD
Day 19
- JVD flat in supine position
- persistent leg edema
- abdominal girth same to slightly decreased
- Na = 136, Cr = 0.8, BUN = 12
- furosemide increased to 80mg QD
- spironolactone increased to 200mg QD
CASE
Day 21
- JVD flat in supine position
- leg edema the same
- Abdominal girth the same
- Na = 130, Cr = 0.9, BUN = 10
Day 24
- 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
UNa
UOsm > SOsm
UNa > 40
UNa
< 10
> 20
YES
NO
< 10
> 20
Volume
Depletion
Mineralcorticoid
Deficiency
SIADH
OTHER
Cirrhosis
Nephrosis
CHF
CKD
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 2cm 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
(mmHg)
< 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
(mmHg)
< 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 1-2cm 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
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
SonoSite 180 Plus
SonoSite 180 Plus
SonoSite 180 Plus
Changing and Inserting
the Transducer
SonoSite 180 Plus
Insert the transducer
Twist lock counterclockwise
SonoSite 180 Plus
Fold lock down
SonoSite 180 Plus
Ready to power-up
machine
SonoSite 180 Plus
Power
Button
SonoSite 180 Plus
SonoSite 180 Plus
SonoSite 180 Plus
SonoSite 180 Plus
Wrong Transducer is
Connected
Correct Transducer Menu
-GYN
-OB
-Abdominal
SonoSite 180 Plus
2D View (default)
M-Mode
SonoSite 180 Plus
GAIN
Changes the contrast
on the screen
SonoSite 180 Plus
SonoSite 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
(mmHg)
< 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
1500cc to 1000cc/d
- Continued current diuretic dosing to
remove free water
Result:
In 3 days, the patient’s Na progressively increased
to 136
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DISCUSSION