The annual incidence of geriatric hip fractures in the United States is 325,000 and is projected to rise given the aging population.1 The mainstay of treatment is cemented hip hemiarthroplasty. Bone cement implantation syndrome (BCIS) is a serious perioperative complication unique to cemented arthroplasty characterized by hypoxia, hypotension, cardiac arrhythmias, and in severe cases, cardiac arrest. BCIS is associated with significantly higher rates of unplanned intubation, vasopressor use, prolonged hospitalization, and 30-day mortality.

Given the rising incidence of hip fractures, the identification of readily modifiable risk factors for BCIS such as anesthetic regimen is crucial to reduce morbidity and mortality. However, a prospective study comparing the rate of BCIS development between general and neuraxial anesthesia is currently lacking. Additionally, no studies have examined how the anesthetic regimen affects histamine and complement levels. Therefore, this pilot study aims to investigate the effect of anesthetic regimen on BCIS development as well as on histamine and complement levels in patients undergoing cemented hemiarthroplasty for hip fracture. The investigators hypothesize that neuraxial anesthesia will be associated with lower rates of BCIS as well as lower histamine and complement levels compared to general anesthesia.

The primary objective of this pilot study is to compare the effect of general and neuraxial anesthesia on the incidence and severity of BCIS in patients undergoing cemented hemiarthroplasty for hip fracture.

Secondary objectives include examining postoperative outcomes associated with BCIS, such as cardiac arrhythmias, unplanned intubation, hypoxia necessitating supplemental oxygen, altered mental status, and in-hospital mortality.

Additional objectives include comparing histamine and complement levels between anesthetic regimens as well as between patients with and without BCIS

This study will be a prospective, randomized pilot study involving adult patients undergoing cemented hemiarthroplasty for hip fracture within the Johns Hopkins healthcare system. In total, 20-24 participants will be randomly assigned to receive either general anesthesia or neuraxial anesthesia with sedation. The use of general or neuraxial anesthesia in this study is consistent with the current standard of care for hip hemiarthroplasty. Randomization will be performed via computer-generated sequences and allocation concealment will be maintained. Blinding patients, anesthesiologists, and orthopedic surgeons to the anesthetic regimen is not possible, but the investigator(s) conducting the statistical analyses will be blinded to the anesthesic regimen.

Patients presenting to the Johns Hopkins system with a hip fracture will be screened for possible participation. If eligible for inclusion, informed consent will be obtained from the patient preoperatively. Patients will subsequently undergo a cemented hip hemiarthroplasty with an orthopedic surgeon under either general or neuraxial anesthesia. Intraoperative vital signs will be monitored in standard fashion and used to detect development of BCIS based upon previously established criteria.

Histamine and complement levels will be measured via blood samples collected at three timepoints: pre-operation, post-induction of anesthesia, and post-cementation. The collection of these labs is for research purposes only and is not part of routine care. Postoperative complications within 30-days of the index surgery will be identified via chart review. Thus, the study duration is 30 days for each patient and requires one visit (hospitalization with index surgery).

Patients that are randomly assigned to neuraxial anesthesia but require conversion to general anesthesia due to unsuccessful spinal or epidural will be considered a treatment failure. These patients will be analyzed per protocol.

Inclusion Criteria:

• Patients >18 years old that are indicated for cemented hemiarthroplasty for hip fracture.

Exclusion Criteria:

• Patients with medical comorbidities that preclude randomization to an anesthetic regimen (e.g., severe aortic stenosis contraindicating general anesthesia or therapeutic anticoagulation contraindicating neuraxial anesthesia) or
• a severe cognitive impairment that precludes the ability to provide informed consent.