Does ultrasonographic measurement of the inferior vena cava diameter correlate with central venous pressure in the assessment of intravascular volume in patients undergoing gastrointestinal surgery?

BACKGROUND: Ultrasonography has been suggested as a useful noninvasive tool for the detection of hypovolemia in critically ill patients. Hypovolemia after preoperative fasting and bowel preparation may compromise hemodynamic function during gastrointestinal surgery. However, there are few data comparing ultrasonographic examination of the inferior vena cava (IVC) diameter with central venous pressure (CVP) measurement in patients undergoing gastrointestinal surgery in the assessment of intravascular volume status.

MATERIALS AND METHODS: Forty American Society of Anesthesiologists I-II patients who underwent elective gastrointestinal surgery and 32 healthy volunteers were enrolled in the study. The IVC diameters, both during expiration (IVCe) and inspiration (IVCi), and right ventricle (RV) were measured with ultrasonography in patients both before and after fluid resuscitation. Volunteers were also measured during the time they participated in the study.

RESULTS: Forty patients (mean age 51 y; 45% female) and 32 volunteers (mean age 46 y; 44% female) underwent IVC and RV sonographic measurements. The diameters of the IVCe, IVCi, and RV in patients (1.83, 1.34, and 3.23 cm) were significantly lower compared with those of healthy volunteers (1.18, 0.62, and 2.71 cm). After fluid resuscitation, IVCe, IVCi, and RV in hypovolemic patients (1.75, 1.25, and 3.27 cm) significantly increased. The pre-IVCe and the post-IVCe were closely correlated to the CVP (r = 0.585 and r = 0.609, respectively). Similarly, the pre-RV and the post-RV were correlated to the CVP (r = 0.347 and r = 0.439, respectively).

CONCLUSIONS: Our data demonstrate that the IVC and RV diameters are consistently low in patients undergoing gastrointestinal surgery when compared with healthy subjects. Ultrasonographic measurements of the IVC and RV diameters are useful supplement of CVP for the evaluation of preoperative patients with hypovolemia.