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Ultrasound in the ICU: Case 1 Discussion
Ultrasound Case 1 Answer: Hypovolemia.
Hypotension may be caused by diverse pathophysiologic states that are hard to differentiate by clinical exam. Bedside ultrasound can provide immediate visual information that can help to rapidly make diagnoses of life-threatening conditions, without dependence on radiology with its associated risks during patient transport. The pertinent ultrasound findings in this patient are:
- Right Ventricle and Left Ventricle: small and hyperdynamic, suggesting underfilling.
- RV/LV ratio: normal, arguing against pulmonary embolism.
- Inferior vena cava: small, not overfilled, arguing against PE.
- Lungs: normal ‘A’ profiles, making pneumothorax unlikely.
- Pericardium: no effusion, ruling out cardiac tamponade.
- Significant intraabdominal fluid with varied echogenicity.
The patient suffered a post-operative intraabdominal haemorrhage, likely due to the combination of surgery and low-molecular weight heparin, administered as his usual warfarin had been held.
Bedside ultrasound examination, performed at admission to the ICU, immediately revealed a very small IVC, becoming visible with positive pressure breaths, hyperdynamic cardiac function (see Clip 2) and clear lungs. Significant intraabdominal fluid was noted to have varied echogenicity, and included a sludge-like portion anterior to the liver edge, consistent with haemorrhage with areas of clotting. Figure 1 shows the longitudinal view of the liver and IVC, showing a collapsed IVC and a large fluid collection with echogenic particles in the near field, anterior to the liver.
The predominant hemodynamic ultrasound pattern was of hypovolemic shock. Massive pulmonary embolism and acute coronary syndrome, which should always be considered in a post-operative patient, were immediately ruled out by ultrasound as critical diagnoses causing shock.
An immediate 22 g needle aspiration was performed under ultrasound guidance at the bedside and confirmed the presence of blood. Volume resuscitation with crystalloids and blood products was completed, anticoagulation reversed, and the patient stabilized.
It is important to integrate the physical examination with ultrasound findings of the IVC. The presence of a very tense abdomen (intraabdominal hypertension) may affect the interpretation of the size of the IVC. Studies to delineate a more specific relationship between intraabdominal pressure (IAP) and IVC size are underway, but most experts agree that a small IVC in the presence of a tense abdomen or IAP > 20 mm hg may not reflect a hypovolemic state.
Videos Copyright Philippe Rola and CCUSI.