OBJECTIVESDescribe indications for using ultrasound at thebedside to image the inferior vena cava.Describe how to performing bedside ultrasound ofthe inferior vena cava.Use the findings on ultrasound to guide assessmentof intravascular volume status.Generate group discussion regarding the potentialvalue of learning this procedure for patientmanagement
CASE46 M was admitted with alcoholic hepatitis and newly diagnosedcirrhosis 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 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.
CASEDay 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 - 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
CASEDay 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 - leg edema the same - Abdominal girth the same to slightly increased - Na = 127, Cr = 0.7, BUN = 13, Urine Na < 10Daily weights and Input/Output measures were collectedsporadically and could not be assessed for any trends.
CLASSIC HYPONATREMIA UNa UOsm > SOsm UNa UNa > 40 < 10 > 20 YES NO < 10 > 20 Volume Mineralcorticoid SIADH OTHER Cirrhosis CKDDepletion Deficiency Nephrosis CHF
QUESTIONWhat type of hyponatremia does this patient have and how should itbe 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 causeA. 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 AssessingIntravascular 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 inpatients who are intubated with shock- Measuring the variation in IVC diameter in these situationscan help determine whether the patient’s blood pressure willrespond to fluids or whether inotropic support (i.e.dobutamine) will be needed
AnatomyThe 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
Respiratory VariationFigure 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=93IVC 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
PROCEDURE LandmarksAproach #1 – Xiphoid View1 Most common approach2 Place probe longitudinally just below the xiphoid process with the probe marker to the patient’s head3 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
PROCEDURE LandmarksAproach #2 – Anterior Mid-Axillary View1 Place probe longitudinally in right anterior mid-axillary line with marker towards the head2 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.
PEARLS Bowel Gas1 May impede visualization in the xiphoid view2 Gentle graded pressure may help move bowel out of way3 Don’t press too hard or will collapse IVC causing false measurements4 Consider anterior mid-axillary view
CASEAn 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)
CASE Correlation Between IVC Diameter Plus CI and CVP IVC Max Diameter CI CVP (cm) (mmHg) 100% < 1.5 0-5 (total collapse) 1.5-2.5 > 50% 6-10 1.5-2.5 < 50% 11-15 > 2.5 < 50% 16-20 0% > 2.5 >20 (no collapse) Interpretation: Mixed hyponatremia(intravascular volume depletion plus free water excess from cirrhosis)
CASETreatment:- 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 waterResult:In 3 days, the patient’s Na progressively increasedto 136
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