Rapid Ultrasonography in Shock: A Lifesaving ED Tool

Rapid Ultrasonography in Shock:  Is this really useful?

Caring for patients with undifferentiated hypotension, causes anxiety for most health care providers.  This is natural.  Fear, however, must not lead to hesitation or poor decision-making.  Therapies chosen early in shock disproportionately impact mortality.  For example, giving fluids to a patient in cardiogenic shock may worsen the outcome, but aggressively giving fluids to a patient in septic shock has proven to be lifesaving.  Being able to properly classify a patient’s shock is critical, but patients are often too unstable to wait for confirmatory lab tests or undergo diagnostic imaging such as CT scans.  Point of care ultrasound allows physicians to expand diagnostic capabilities at the bedside, and in real time, collect information that will favorably affect outcomes.

The Rapid Ultrasonography in Shock (RUSH) exam, was developed to give providers a framework for managing hypotensive medical patients.  In brief, the exam focuses on three physiologic parameters, the pump, the tank and the pipes.  Examining the heart (pump) from four basic positions, identifies the presence of pericardial fluid, abnormal left ventricular contractility and acute right ventricular strain.  Measuring the diameter and respiratory change of the inferior vena cava (tank), provides an estimate of volume status-and more importantly volume responsiveness.  Assessment of the abdominal aorta (pipe), identifies dissection or aneurysmal dilatation, and finally compressing the deep veins of the legs (more pipes), detects deep vein thromboses.  See the original article on RUSH by Dr. Perera for details on how these exams are completed.¹

Are we as emergency providers capable of learning the RUSH exam? 

A significant body of evidence supports the proficiency of emergency medicine and hospital medicine providers in using point of care ultrasound to complete the various parts of the RUSH exam.  For example, compared to cardiologists reading formal echocardiograms, emergency physicians with 2 days of training accurately predicted ejection fraction as normal, moderately depressed or severely depressed 84% of the time. ²  Calculation of the IVC distensibility index ((largest IVC diameter-smallest IVC diameter)/smallest IVC diameter) accurately predicts fluid responsiveness in critically ill patients.  A distensibility index greater than 18% predicted a rise in cardiac index of greater than 15% with greater than 90% sensitivity and specificity.³  In a study evaluating accuracy of aortic diameter measurements, 3^rd year emergency medicine residents had near perfect correlation with formal ultrasonography. ⁴ Finally, emergency physicians with one hour of training were able to exclude DVT with 95% negative predictive value using compression venography.  Each physician performed five supervised exams in training prior to participating in the study. ⁵

How will this change what I do in the ED?

Recently, a 58 year-old woman from out of town came to our ER with substernal chest pain.  The EKG showed left bundle branch block.  With no comparison EKGs to review, we performed a limited bedside echo and saw septal hypokinesis.  This information influenced the cardiologist to take the patient for cardiac catheterization despite negative cardiac enzymes.  A 90% lesion of the left anterior descending artery was discovered.  A 73 year-old woman hospitalized a week earlier with a UTI, had syncope during physical therapy.  She was profoundly hypotensive, and with bedside ultrasound had a large right ventricle, a septum bowing to the left, a full IVC and an uncompressible common femoral vein.  She was given thrombolytics and her shock resolved within 30 minutes.  A 48 year-old cirrhotic patient had a cardiac arrest on arrival to the emergency department.  After resuscitation, his bedside ultrasound showed a hyperdynamic heart, a flat IVC and large amount of peritoneal fluid.  On peritoneal aspiration, the fluid was bloody not ascitic.  The patient was rushed to the OR and found to have a bleeding mesenteric varix. 

Rapid Ultrasonography in Shock is a bedside physiologic assessment using point of care ultrasound.  The exam can be performed competently with limited training and practice, and provides invaluable information in managing the sickest patients in the emergency department.

1.  Perera, et al.  The RUSH Exam:  Rapid Ultrasound in Shock in the Evaluation of the Critically Ill, Emerg Med Clin N Am 28 (2010) 29-56.

2.  Moore, MD et al.  Determination of Left Ventricular Function by Emergency Physician Echocardiography of Hypotensive Patients, Acad Emerg Med, March 2002, Vol 9, No 3.

3.  Barbier, et al.  Respiratory changes in inferior vena cava diameter are helpful in predicting fluid responsiveness in ventilated septic patients.  Inten Care Med (2004) 30:1740-1746.

4.  Costantino TG, et al.  Accuracy of Emergency Medicine Ultrasound in the Evaluation of Abdominal Aortic Aneurysm.  J of Emerg Med. Vol. 29, 2005. No 4;455-460.

5.  Frazee, et al.  Emergency Department Compression Ultrasound to Diagnose Deep Vein Thrombosis, J Emerg Med, 2001 Feb:20 (2):107-12.

Ultrasound-Guided Peripheral IVs: An Alternative to Central Venous Catheters?

One of the most common indications for placing a central venous catheter is “no IV access”.  I certainly have placed numerous central lines for this reason.  Unfortunately, this practice is not without consequences.  In addition to patient discomfort and mechanical complications, central line associated blood stream infections (CLABSI) occur in U.S. hospitals approximately 250,000 times per year.  By conservative estimates each CLABSI lengthens hospital stay by two weeks, increases cost by $30,000 and carries a mortality that ranges from 12 to 25%.  CLABSIs can be reduced by adhering to proven practices during insertion and maintenance of central lines.  However, there is also a direct correlation between CLABSI rates and a hospital’s device utilization ratio, defined as the number of central line days divided by the number of patient days in a hospital.  Wouldn’t it be nice if we could just insert fewer central lines?

The use of ultrasound guidance for peripheral IV insertion has been described as early as the 1970s but has increased in the last eight years with the rise of point of care ultrasound.¹  Most patients with difficult venous access lack visible, palpable veins near the surface of the skin.  Edema, obesity, dehydration, IVDA and frequent venipuncture can all cause this problem.  The ultrasound machine can be used to visualize veins deeper beneath the surface of the skin that are often larger, less mobile and have not been previously punctured.  Ultrasound-guided peripheral IVs may be placed by physicians or nurses, can be learned quickly and have high success rates. In an ER setting, Bauman et al saw an 87% success rate among nurses placing ultrasound-guided peripheral IVs for difficult access patients.¹ Gregg et al showed that in a mixed ICU over a 6 month period, 148 requests were received to place ultrasound-guided peripheral IVs after traditional IV access failed, and ultrasound-guided peripheral lines were placed successfully in 147 of those cases.²  While early studies showed low rates of “IV survival” when placed under ultrasound guidance, this problem has largely been eliminated by the use of longer IV catheters, with more of their length within the actual vein.  Infection rates have been shown to be low and comparable to traditional IV insertion using standard aseptic technique.  Finally patient satisfaction with this technique is high.³  Schoenfeld and colleagues surveyed patients who underwent ultrasound-guided peripheral IV insertion and found that the study population, 62% of whom had a central line placed in the past year, had an average satisfaction score of 9.2 out of 10.4⁴

In my practice, I have found an important role for ultrasound-guided IV access.  In the emergency department, the technique has allowed us to avoid placing central venous catheters in patients who otherwise wouldn’t need them.  In the intensive care unit, ultrasound-guided lines are placed so that existing central lines may be removed.  Both doctors and nurses have learned the technique and are inserting lines with high success rates.  To learn more about ultrasound-guided peripheral IV insertion visit us at www.hospitalprocedures.org.

1.  Bauman et al.  Ultrasound-guidance vs. standard technique in difficult vascular access patients by ED technicians.  Am J Emerg Med. 2009 Feb;27(2):135-40.

2.  Gregg et al.  Ultrasound-guided peripheral intravenous access in the intensive care unit.  J Crit Care. 2010 Sep;25(3):514-9.

3.  Adhikari et al.  Comparison of infection rates among ultrasound-guided versus traditionally placed peripheral intravenous lines. J Ultrasound Med. 2010 May;29(5):741-7.

4.  Schoenfeld et al.  Ultrasound-guided peripheral venous access in the emergency department:  A patient centered survey.  Western Journal of Emerg Med.  Nov, 2011:475-77.

Dargin et al.  Ultrasonography-guided peripheral intravenous catheter survival in ED patients with difficult access.  Am J Emerg Med. 2010 Jan;28(1):1-7