Introduction: Evaluation of the hemodynamic status in the critically ill patient is a part of everyday practice in the ICU. The results of this assessment are of crucial importance because of their role in determining the optimal treatment and prediction of its efficacy. Prompt and accurate recognition of patients in shock and identification of its potentially reversible causes is the first step towards successful treatment. Ultrasound provides insight into cardiac function, intravascular volume status and the morphology of the main blood vessels – the three major determinants of hemodynamic status.
The aim of this paper was to emphasize the utility of bedside ultrasound as a non-invasive tool which can offer clinicians valuable information about possible causes of a patient’s hemodynamic instability.
Patients and Methods: In this study we presented four different patients admitted to the medical ICU with a similar initial clinical presentation of hemodynamic instability (hypotension, tachycardia, tachypnea, altered mental status), where point-of-care ultrasound examination with a convex abdominal probe revealed the causes of undifferentiated hypotension and guided further treatment towards specific procedures.
Case 1. A 47 year-old female patient with no previous medical history presented to the ED with dyspnea as her leading symptom. She was orthopneic, hypotensive; ECG showed sinus tachycardia and microvoltage in the limb leads. She was admitted to the ICU for further examination.
Case 2. A 50 year-old female patient was admitted to the ICU due to a massive PE she developed 7 days after hernioplasty of an incarcerated ventral hernia. Enoxaparin in the therapeutic dose was instituted. On the 10th postoperative day she suddenly became dyspneic, with SpO2 < 75% and systolic blood pressure < 90 mm Hg.
Case 3. A 79 year-old female patient with a previous history of severe cardiomyopathy (EF 20%) presented to the ED with acute GI bleeding and consequential renal failure. After initial hemodynamic stabilization with RBC she was transferred to the ICU with the intention to initiate dialysis. Serum creatinine was 455 umol/L, urea was 60.9 mmol/L and potassium was in normal range.
Case 4. A 67 year-old male patient who was hypotensive, febrile, with hypoxemic respiratory failure was admitted due to extensive right sided pneumonia. He was intubated, mechanical ventilation was instituted, but he suffered cardiac arrest.
Results: After ICU admission, all of the aforementioned patients underwent ultrasound examination performed by the attending intensivist.
In the first case, ultrasound revealed an enlarged pericardium, with the collapse of the RA and RV. IVC was dilated with reduced inspiratory collapse. The diagnosis of pericardial effusion was made and immediate pericardiocentesis was performed.
In the second case, ultrasound showed RV strain (RV dilatation with paradoxical septal wall motion), dilated IVC with no inspiratory collapse and thrombus in the right femoral vein. The patient was diagnosed with PE and rTPA was started, leading to normalization of hemodynamics and oxygenation.
In the third case, signs of hypovolemia and impaired cardiac function were observed. Since there were no signs of lung congestion, the strategy of reinstitution of volume status was chosen (instead of immediate dialysis). Reduced heart function limited the possibility of liberal volume replacement. Closely monitoring the signs of extravascular lung water (according to the FALLS protocol), careful volume replacement was performed until the first B lines appeared. Hypotension was corrected, diuresis re-established and renal function gradually improved without the need for dialysis.
In the fourth case, significant absolute hypovolemia together with poor heart performance was the main sonographic finding. It can be assumed that reduced peripheral vascular resistance, induced by sepsis, was also an important contributing factor to hemodynamic instability. Further deterioration was a direct consequence of the negative hemodynamic effects of positive pressure ventilation. Volume restitution was the most important part of resuscitation, but beta-1 agonists and vasopressors were also required in order to stabilize the patient.
Discussion: These four cases demonstrate how completely different conditions can have a similar initial presentation (when assessed only through the numeric values of blood pressure, pulse and respiratory rate). Differentiating shock into cardiogenic, obstructive, hypovolemic or distributive is often a very challenging task for a physician with a great impact on further patient management. Today, the use of invasive hemodynamic monitoring is ubiquitous in the ICU, but often it is not enough for the rapid establishment of the causes of the hemodynamic collapse. The availability of the ultrasound in the ICU, its application in the assessment of shock and helpfulness in guiding therapeutic procedures should make sonographic examination an integral part of the clinical evaluation of every patient admitted to the ICU.
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