Ultrasound measurement of inferior vena cava collapse predicts propofol-induced hypotension

Abstract

Study objectives: Hypotension is a common side effect of propofol, but there are no reliable methods to determine which patients are at risk for significant propofol-induced hypotension (PIH). Ultrasound has been used to estimate volume status by visualization of inferior vena cava (IVC) collapse. This study explores whether IVC assessment by ultrasound can assist in predicting which patients may experience significant hypotension.

Methods: This was a prospective observational study conducted in the operating suite of an urban community hospital. A convenience sample of consenting adults planned to receive propofol for induction of anesthesia during scheduled surgical procedures were enrolled. Bedside ultrasound was used to measure maximum (IVCmax) and minimum (IVCmin) IVC diameters. IVC-CI was calculated as [(IVCmax-IVCmin)/IVCmax × 100%]. The primary outcome was significant hypotension defined as systolic blood pressure (BP) below 90mmHg and/or administration of a vasopressor to increase BP during surgery.

Results: The study sample comprised 40 patients who met inclusion criteria. Mean age was 55years, (95%CI, 49-60) with 53% female. 55% of patients had significant hypotension after propofol administration. 76% of patients with IVC-CI≥50% had significant hypotension compared to 39% with IVC-CI<50%, P=.02. IVC-CI≥50% had a specificity of 77.27% (95%CI, 64.29%-90.26%) and sensitivity of 66.67% (95%CI, 52.06%-81.28%) in predicting PIH. The odds ratio for PIH in patients with IVC-CI≥50% was 6.9 (95%CI, 1.7-27.5).

Conclusion: Patients with IVC-CI≥50% were more likely to develop significant hypotension from propofol. IVC ultrasound may be a useful tool to predict which patients are at increased risk for PIH.