- Introduction: Assessment of fluid responsiveness (FR) is used to guide volume resuscitation; however, the reliability and accuracy of the passive leg raise (PLR) and fluid bolus (BOLUS) techniques are undefined in the emergency department (ED) setting. Hypothesis: Using the NICOM monitor, we assessed the reproducibility and accuracy of PLR and BOLUS in predicting FR in spontaneously breathing ED patients. Methods: Prospective, observational study of ED patients. Inclusion criteria: IV fluid bolus part of treatment, age >18, and ability to tolerate protocol. Patients were excluded if clinical acuity precluded participation. The hospital IRB approved the study. We used the NICOM monitor (Cheetah Medical, Tel Aviv, Israel) to assess stroke volume (SV) and obtained 4 measurements in sequence: PLR1, PLR2, BOLUS1 separated by 10 minutes, BOLUS2 was initiated immediately after BOLUS1. For PLR, the head of the bed was changed from semi-recumbent to supine position and the patients’ legs were raised to 45° for 3 minutes. Maximum increase in SV was recorded. BOLUS was defined as 5cc/kg NS infusion over 10-15 minutes; the maximal increase in stroke volume was recorded. FR was defined as increase in SV >10% from baseline. We calculated kappa statistic, correlation coefficients and operating characteristics with 95% confidence interval. Results: There were 88 patients enrolled in the study. The two PLRs were highly correlated (r=0.88, p<0.001), with a kappa for FR of 0.6. In contrast, the two BOLUSES had a correlation of 0.12 and k=0.2 for FR. When we calculated the operating characteristics for predicting FR>10% to a subsequent fluid infusion, we found that the sensitivity for each technique was similar (80% and 81%, respectively), but the specificity had a higher point estimate for PLR compared to BOLUS (64%, 95% CI 44–79% vs 41%, 34-59%). PLR had an overall accuracy of 76% (65-84%) compared to 61% (50-70%) for the BOLUS technique in predicting FR to a subsequent fluid challenge. Conclusions: The PLR method of assessing FR using the NICOM was reasonably reproducible and accurate. While additional patient recruitment is warranted, initial data suggests that PLR measured by NICOM is a promising technique of FR assessment in the ED.