Abstract
BACKGROUND: Internal jugular vein respiratory variation (IJVV) has been proposed as a dynamic predictor of fluid responsiveness. However, its utility is limited in patients with low tidal volume (Vt) ventilation in the prone position. We conducted this study to determine whether a transient increase in Vt from 6 to 8 ml kg(-1) of the predicted body weight (PBW), which is the "tidal volume challenge (TVC)", improves the feasibility of the IJVV in patients undergoing posterior lumbar surgery ventilated with a low Vt. METHODS: This was a prospective study conducted in the operating room. Patients were studied at baseline (a Vt of 6 ml kg(-1) PBW), during a 1 min increase in the Vt to 8 ml kg(-1) of the PBW, during a 1 min shift to the Trendelenburg maneuver, and after fluid administration. Baseline values of the IJVV, pulse pressure variation (PPV), and stroke volume variation (SVV) [IJVV(6), PPV(6), and SVV(6), respectively], and the changes in the IJVV during a TVC (ΔIJVV(6-8)) were measured. The change in cardiac index during a Trendelenburg maneuver (ΔCI(trend)) was also recorded. Volume responsiveness was defined by a ΔCI(trend) ≥ 8%. The primary outcome was determination of the ΔIJVV(6-8) in predicting volume responsiveness during low Vt ventilation in the prone position. The secondary outcomes included an estimation of the IJVV(6), PPV(6), and SVV(6) diagnostic performances in predicting volume responsiveness in this surgical setting. RESULTS: Sixty-one patients were included in the study, 31 (50.82%) of whom were deemed volume responsive. The ΔIJVV(6-8) predicted volume responsiveness with area under the receiver operating characteristic curve (AUC) of 0.96 (95% CI 0.88-0.99; P < 0.001), with a sensitivity of 96.77% and a specificity of 86.67%. In addition, the AUC for ΔIJVV(6-8) was significantly higher than that for IJVV(6), PPV(6), and SVV(6), as confirmed by DeLong's test (P = 0.04, P < 0.001, and P = 0.01, respectively). CONCLUSIONS: In patients undergoing posterior lumbar surgery with low Vt ventilation, changes in IJVV during a TVC effectively predict volume responsiveness and are more reliable than IJVV, PPV, and SVV in this surgical context.