Surgeon-performed bedside ultrasound to assess volume status: a feasibility study.

Purpose: Rapid assessment of volume status in children is often difficult. The purpose of this study was to evaluate the feasibility of surgeon-performed ultrasound to assess volume status in patients with hypertrophic pyloric stenosis.

Methods: Ultrasounds were performed on admission and before operation. The diameters of the inferior vena cava (IVC) and aorta (Ao) were measured and IVC/Ao ratios were calculated. Electrolytes were measured on admission and repeated if warranted. Logistic regression was used to associate the clinical outcome, defined as CO2 ≤30 mEq/L, with IVC/Ao ratios. Predictive capacity was estimated from the logistic regression for IVC/Ao ratios. Linear regression was used to estimate associations between CO2 values and IVC/Ao ratios.

Results: Thirty-one patients were enrolled. The IVC/Ao ratio is highly associated with actual CO2 values (P < 0.001) and the clinical outcome (P = 0.004). For every 0.05 unit increase in IVC/Ao ratio, predicted CO2 decreased 1.1 units. For every 0.05 unit increase in the IVC/Ao ratio, the odds of having a CO2 ≤30 mEq/L increased 48% [OR = 1.48, 95% CI (1.13,1.94)]. Predictive capacity is maximized at an IVC/Ao ratio of 0.75 as 83.9 % of subjects were correctly classified and specificity and PPV = 100%.

Conclusions: Surgeon-performed ultrasound to determine IVC/Ao ratio is feasible. An IVC/Ao ratio of 0.75 predicted adequate resuscitation.