The purpose of this study is to determine whether Hemospan is superior to Voluven for treatment of hypotensive episodes during the perioperative period (from induction of spinal anesthesia until 6 hours after skin closure), and for reducing the incidence of operative and postoperative complications including organ dysfunction and failure until follow-up at one month following surgery. An independent Data Safety Monitoring Board (DSMB) will periodically evaluate the safety data collected during this trial

Hemospan is a novel hemoglobin-based oxygen carrier developed to perfuse and oxygenate tissue at risk for ischemia and hypoxia. As a result of its molecular size and oxygen binding characteristics, Hemospan selectively off-loads oxygen in tissues predisposed to low oxygen tension. Preclinical evidence suggests that Hemospan provides rapid and effective plasma expansion and tissue perfusion, and that the properties of Hemospan target oxygen release in the microcirculation.

Spinal anesthesia is the preferred choice for hip arthroplasty procedures in elderly patients, but is associated with a functional hypovolemia due to loss of vascular tone that frequently causes acute hypotensive episodes. Hypotension represents a surrogate marker of hypovolemia that may be further exacerbated by surgical bleeding, which can result in decreased cardiac output, insufficient perfusion and inadequate tissue oxygenation. Ischemia resulting from hypotension can adversely affect vital organ function and may result in complications and postoperative morbidity. As the population ages and more patients become candidates for orthopedic reconstruction or joint replacement surgery, the number of patients at risk is increasing. The ideal IV solution for treating hypovolemia-associated hypotension and improving hemodynamic stability would be an effective plasma expander that promotes tissue perfusion and delivers oxygen to ischemic or marginally hypoxic tissue.

Preclinical animal studies have shown that Hemospan may be well-suited to this application and may even be better than blood in some situations. Data from Sangart's Phase II orthopedic surgery study (No. 6055), published recently by Olofsson et al. (Anesthesiology 2006; 105(6):1153-63) support the safety and potential benefit of Hemospan for preventing and treating hypotension in orthopedic surgery patients undergoing hip replacement surgery under spinal anesthesia.

Inclusion Criteria:

• Patients scheduled to undergo elective primary hip arthroplasty (based on an osteoarthritis diagnosis) under spinal anesthesia
• Adult male or female (surgically sterile or post-menopausal), aged 50 years or older
• American Society of Anesthesiology (ASA) Class II or III
• Physical examination, laboratory status, vital signs, and ECG within acceptable limits for the planned surgery, as judged by the investigator
• Have been given written and verbal information by the investigator about Hemospan and the protocol, and have had the opportunity to ask questions about the study
• Patients must sign an Informed Consent form that has been reviewed and approved by the independent Ethics Committee

Exclusion Criteria:

• Hip fracture patients and nail/pin extraction procedures
• Clinical evidence of uncontrolled cardiovascular, infectious, psychiatric, metabolic or systemic disorders including diabetes and rheumatoid arthritis
• Evidence of significant hypertension with SBP >180 mmHg, or a difference in SBP obtained in each arm that is >15 mmHg (measured in the supine position in both arms, at screening)
• Recent history or evidence of MI or stroke (within 6 months)
• Known alcohol or drug dependency
• Currently taking oral anti-coagulant therapy; except for low-dose aspirin (acetylsalicylic acid), <200 mg/day
• History of coagulopathy
• Involved in any investigational drug or device trial within 30 days prior to this study
• Professional or ancillary personnel involved with this study