From the Guidelines
The patient's IVC diameter of 1.3 cm with respiratory variation greater than 50% and low RA pressure of approximately 3 mmHg suggests adequate volume status and no need for fluid expansion, as indicated by experts' opinion on management of hemodynamics in ARDS patients 1.
Key Findings
- The IVC diameter and respiratory variation are consistent with normal cardiac filling pressures and euvolemia.
- The significant respiratory variation in IVC diameter occurs due to increased venous return to the right heart during inspiration, causing the IVC to collapse partially.
- This degree of collapse in a normal-sized IVC suggests the patient is not volume overloaded.
Clinical Implications
- These findings would indicate no need for diuresis and would be reassuring in patients being evaluated for conditions like heart failure, where elevated right-sided pressures might be concerning.
- The use of norepinephrine and respiratory settings adaptation, such as limiting hypercapnia and prone position, may be considered to manage hemodynamic failure in ARDS patients 1.
- Early identification of sepsis and prompt administration of intravenous fluids and vasopressors are always mandatory, with a goal of restoring a mean systemic arterial pressure of 65 to 70 mmHg 1.
From the Research
Respiratory Variation in Inferior Vena Cava Diameter
- The respiratory variation in inferior vena cava diameter (DeltaD(IVC)) has been studied as a guide to fluid therapy in mechanically ventilated patients 2.
- A study found that DeltaD(IVC) was greater in responders to volume loading than in non-responders, and a 12% DeltaD(IVC) cut-off value allowed identification of responders with positive and negative predictive values of 93% and 92%, respectively 2.
- However, a systematic review and meta-analysis found that respiratory variation in IVC diameter has limited ability to predict fluid responsiveness, particularly in spontaneously ventilating patients 3.
Prediction of Fluid Responsiveness
- The prediction of fluid responsiveness is crucial in patients with acute circulatory failure, as it allows fluid resuscitation to be administered to those most likely to benefit 3.
- A study found that high respiratory variation in IVC diameter values (>40%) are usually associated with fluid responsiveness in spontaneously breathing patients with acute circulatory failure, while low values (<40%) do not exclude fluid responsiveness 4.
- However, another study found that respiratory variation of inferior vena cava diameter fails to predict fluid responsiveness in mechanically ventilated patients with isolated left ventricular dysfunction 5.
Clinical Implications
- The optimal choice of infusate should be guided by the cause of hypovolemia, the cardiovascular state of the patient, the renal function, as well as the serum osmolality and the coexisting acid-base and electrolyte disorders 6.
- Clinicians should be aware of any coexisting disorders in patients with hypovolemia and guide their choice of infusate treatment based on the overall picture of their patients 6.
- The use of Lactated Ringer's infusate should be considered, as it is a balanced solution that can help correct acid-base and electrolyte disorders 6.