Inferior vena cava diameter as a guide in hypotensive patients for appropriate saline therapy: An observational study

Knowledge of intravascular volume (IV) status of a hypotensive patient is of utmost importance. Clinical evaluation and central venous pressure (CVP) measurement are routinely used as a guide for evaluation of IV in these patients. However, clinical assessment may be inaccurate, and CVP measurement is invasive. Moreover, CVP changes slowly with saline therapy, which is unfavorable for fluid resuscitation.

Our aim is to find the correlation and sensitivity of inferior vena cava (IVC) diameter measured by ultrasound to provide a noninvasive method for evaluation of IV among patients with hypotension and hypovolemia in the emergency department (ED).

We measured the IVC diameter of hypotensive patients before and after saline therapy. As all of the patients had central venous line (CV-line) in place, CVP was also measured before and after. Using MedCalc and SPSS software the correlation between these two was determined as expressed with "r." Then, receiver operating characteristic (ROC) curve was sketched.

Ninety-nine patients, 49 (49.5%) males, were evaluated. Mean systolic blood pressure was 90 mmHg with a mean hazard ratio about 104. IVC diameter was 7.44 ± 5.13 mm before and 9.84 ± 5.29 after (P = 0.002) saline therapy. There was a high correlation between IVC diameter and CVP (r = 0.941, P < 0.0001 before saline therapy and r = 0.95, P < 0.0001 after saline therapy). ROC curve for IVC diameter shows a very high sensitivity for all criteria values.

IVC diameter measurement using ultrasonography has excellent correlation with CVP. This method is very sensitive to rapid IV changes thus useful to guide saline therapy in hypotensive patients referred to ED. However, its use in certain subsets of patients' needs further studies.