The primary objective of this study is to evaluate the performance of the Acumen™ Assisted Fluid Management (AFM) Feature in its ability to predict a subject's fluid responsiveness.

The primary objective of this study is to evaluate the performance of the Acumen™ Assisted Fluid Management (AFM) Feature in its ability to predict a subject's fluid responsiveness.

Subjects enrolled in the validation study will have their fluid management decisions guided by the AFM Feature.

Inclusion Criteria:

• Be ≥ 18 years of age
• Abdominal, pelvic, major peripheral vascular surgery expected to last >2 hours post anesthesia induction
• Participate or have authorized representative participate in the Informed Consent process and sign/date the IRB approved informed consent form.

Exclusion Criteria:

• Are < 18 years of age
• Emergent or cardiovascular surgical procedure
• Are pregnant
• Participation in any other drug, device, or biologic study concomitantly, or within the last 30 days (which may clinically interfere with this Clinical Study)
• Refusal of patient or authorized representative to sign consent