Changes in internal jugular vein respiratory variation during tidal volume challenge predict volume responsiveness in lumbar surgery under protective ventilation: a prospective cohort study.

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) [IJVV₆, PPV₆, and SVV₆, 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 IJVV₆, PPV₆, and SVV₆ 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 IJVV₆, PPV₆, and SVV₆, 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.