Summary Management of fluid administration is of major importance in the intensive care unit (ICU). While hypovolemia may lead to organ dysfunction positive cumulative fluid balance is associated with an increase in both morbidity and mortality. Patients and Methods: The selected patients mechanically ventilated using the volume-controlled mode; the tidal volume adjusted to 8 ml/kg (based on the patient's predicted body weight). We gave muscle relaxant (cisatracurium 0.1mg/kg) to prevent spontaneous breathing activity. The hemodynamic variables included (heart rate, mean arterial pressure (MAP), central venous pressure (CVP), diameter of LVOT (cm²), VTI (cm) and Vmax (cm\sec) measurements were recorded before, at the end of a 15-sec end expiratory occlusion maneuver (within less than 1 minute) and just after fluid challenge by performed using 500 mL of saline 0.9% over 15 minutes. Fluid responders were identified when cardiac output increased more than 15% after fluid challenge. End Expiratory Occlusion maneuver performed by interrupting the mechanical ventilation at end-expiration (just before next insufflation) over 15 sec using the software function “expiratory hold “to prevent next breath. - Results: A total of 48 shocked patients were enrolled in this study. Twenty -six (54.1%) patients were fluid responders. A 15 sec EEO maneuver induced a significant increase in VTI (13.86 ± 4.85% in responders versus 6.19±2.58% in non-responders), in Vmax (10.13± 4.36% in responders versus 5.72± 2.64% in non-responders) and an increase in stroke volume (13.86±4.85% in responders versus 6.19±2.58% in non-responders). - It was able to determine fluid responsiveness with an increase in VTI >9.55 % (best cut-off) with accuracy (92.0%), sensitivity and specificity was 84.6% and 95.5% respectively (p< 0.001) EEO or with an increase in Vmax >8.69 % (best cut-off) with accuracy (79.50%), sensitivity and specificity was 57.7% and 90.9% respectively (p< 0.001). The AUROC curve generated for changes in VTI was significantly higher than the one generated for changes in Vmax (0.922 versus 0.795, respectively, P < 0.001). Conclusion: Our study suggested that in mechanically ventilated and sedated ICU patients, a 15-second EEO can reliably predict fluid responsiveness. An increase in VTI of >9.55% or Vmax >8.69% was able to predict fluid responsiveness. Change in VTI was able to predict fluid responsiveness and performed better than change in Vmax.