2OBJECTIVESDescribe 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
3CASE46 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 protocolHospital CourseDay 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.
4CASE 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 QDDay 19- abdominal girth same to slightly decreased- Na = 136, Cr = 0.8, BUN = 12- furosemide increased to 80mg QD- spironolactone increased to 200mg QD
5CASE Day 21 - JVD flat in supine position - leg edema the same - Abdominal girth the same- Na = 130, Cr = 0.9, BUN = 10Day 24- JVD flat in the supine position- Abdominal girth the same to slightly increased- Na = 127, Cr = 0.7, BUN = 13, Urine Na < 10Daily weights and Input/Output measures were collected sporadically and could not be assessed for any trends.
7QUESTIONWhat type of hyponatremia does this patient have and how should it be managed?Hypovolemic hyponatremiastop 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 causeHypervolemic hyponatremiaincrease 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.Not sureconsult nephrology for an opinion about the hyponatremia
9Intravascular Volume Status / CVP INDICATIONSAssessingIntravascular Volume Status / CVPVOLUME DEPLETED STATES- HyponatremiaAcute Kidney Injury (? Prerenal)Diuretic therapySepsisVOLUME OVERLOAD STATESHyponatremiaHeart FailureCirrhosis with ascitesAnasarca
10Fluid Responsiveness in Shock INDICATIONSAssessingFluid 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
11AnatomyThe inferior vena cava returns blood from the body to the right atriumFormed by the convergence of the illiac veinsRetroperitonealRight of the aortaNormal size <2.5 cmVaries w respiration
18CAVAL INDEX (CI) CI = maximum (expiratory) diameter minimal (inspiratory) diameterCI =maximum (expiratory) diameter
19CAVAL INDEX (CI)0%100%VolumeOverloadVolumeDepletion
20Correlation Between IVC Diameter Plus CI and CVP IVC v CVPCorrelation Between IVC Diameter Plus CI and CVPIVC Max Diameter(cm)CICVP(mmHg)< 1.5100%(total collapse)0-5> 50%6-10< 50%11-15> 2.516-200%(no collapse)>20
23Correlation Between IVC Diameter Plus CI and CVP IVC v CVPCorrelation Between IVC Diameter Plus CI and CVPIVC Max Diameter(cm)CICVP(mmHg)< 1.5100%(total collapse)0-5> 50%6-10< 50%11-15> 2.516-200%(no collapse)>20
24PROCEDURE Positioning Supine Degree of head elevation has not been shown to make a significant difference in measurements
25PROCEDUREProbe SelectionLow frequency 2-5 MHzCurvalinear probe
27PROCEDURE Landmarks Aproach #1 – Xiphoid View Most common approach Place probe longitudinally just below the xiphoid process with the probe marker to the patient’s headLook 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
30PROCEDURE Landmarks Aproach #2 – Anterior Mid-Axillary View Place probe longitudinally in right anterior mid-axillary line with marker towards the headLook for IVC running longitudinally adjacent to liver crossing the diaphragm.Track superiorly until it enters right atrium confirming that it is the IVC and not the aorta.
32PEARLS Bowel Gas May impede visualization in the xiphoid view Gentle graded pressure may help move bowel out of wayDon’t press too hard or will collapse IVC causing false measurementsConsider anterior mid-axillary view
52CASE An IVC Ultrasound was performed at the bedside. Maximum IVC diameter during expiration = 1.10 cm. TheMinimum IVC diameter during inspiration = 0 cm.Caval Index = 100% (total collapse)
53Correlation Between IVC Diameter Plus CI and CVP CASECorrelation Between IVC Diameter Plus CI and CVPIVC Max Diameter(cm)CICVP(mmHg)< 1.5100%(total collapse)0-5> 50%6-10< 50%11-15> 2.516-200%(no collapse)>20Interpretation:Mixed hyponatremia(intravascular volume depletion plus free water excess from cirrhosis)
54CASE Treatment: one liter of normal saline IV to expand intravascular volume- reduced free water oral intake from1500cc to 1000cc/d- Continued current diuretic dosing toremove free waterResult:In 3 days, the patient’s Na progressively increased to 136
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