High-risk spine surgery refers to a surgical procedure with prolonged duration and large anticipated volume of blood loss, or one who is performed on a patient that has significant medical comorbidity prior to surgery. For example, revision surgery and surgery to correct adult spinal deformity are frequently considered high-risk spine surgeries.

These surgeries represent the pinnacle of complexity in spine surgery and are known to be accompanied by a number of risks. The complication rate for adult scoliosis surgery, for example, has been quoted to be between 37 percent and 86 percent. These risks include significant blood loss, postoperative infection, neurologic deficit, myocardial infarction, pneumonia, pulmonary embolism, blindness, and death.

After two poor patient outcomes in rapid succession following adult spinal deformity surgery, surgeons at Northwestern Memorial Hospital decided to postpone further high-risk spine procedures until we could implement a program to more effectively manage these complex patients.

The first step was a root cause analysis to identify risk factors associated with poor outcomes following this type of surgery. Next, a multidisciplinary team interpreted the data, performed an exhaustive literature review, and developed a plan to manage patients undergoing high-risk spine surgery. The team involved orthopaedic spine surgeons, neurosurgeons, anesthesiologists, perioperative medicine specialists, hematologists, and operating room (OR) nursing staff as well as the hospital’s chief medical officer and members of the quality assurance team.

Ultimately, a protocol was developed and recently published that judiciously selects operative candidates and minimizes their operative risk by identifying and optimizing medical comorbidities. The protocol also provides an algorithm for intraoperative and postoperative management of these patients.

Defining high-risk patients
The first portion of the protocol is designed to define which patients are considered high risk (Table 1). Both surgical and medical risk factors are assessed.

Surgical risk factors include an anticipated surgery time of more than 6 hours or planned surgery on greater than 6 spine levels. Surgeries that involve staged approaches, anterior and posterior surgeries, and procedures that, in the subjective judgment of the surgeon, expose the patient to an increased level of surgical risk are also considered high-risk surgeries.

Medical inclusion criteria, determined by internists, include a history of coronary artery disease, congestive heart failure, cirrhosis, dementia, emphysema, renal insufficiency, pulmonary hypertension, or stroke, and age older than 80 years. If the patient meets any of these criteria, the “High-Risk Spine Protocol” is initiated.

Once a high-risk patient is identified, the surgeon initiates a formalized patient work-up and designates a level of surgical risk. Patients are then assigned to a perioperative internist and undergo a series of preoperative tests, including standard preoperative labs as well as tests to evaluate the cardiac and pulmonary status.

An anesthesiologist who specializes in high-risk spine surgery then reviews the surgeon’s work-up and all test results. The anesthesiologist prepares recommendations and presents them at a multidisciplinary preoperative conference. The surgeon, internist, and anesthesiologist not only review test results, they also develop a specific intraoperative plan for the patient. Following this discussion, they make a joint decision to either cancel or proceed with the surgery.

Intraoperative management

Anesthesiology and nursing staff who cover these cases have been trained in the protocol and have taken an active role in educating others about this initiative. In addition to the formal training, staff benefit from a placard posted in all high-risk spine surgery ORs.

Once the patient enters the OR, a specific protocol is initiated. (See the online version of this article, available at www.aaosnow.org, for a copy of the OR protocol.) It includes guidelines for lab tests, transfusion therapy (cryoprecipitate and platelet guidelines), neurologic testing, temperature (room, patient, fluids, anesthesia), and equipment.

The placard posted in the OR lists the intraoperative management protocol and may be referenced by the primary anesthesiologist and any other anesthesiologist who may provide temporary coverage.

The temperature in the OR is set at approximately 70 degrees Fahrenheit and is maintained until the patient exits the room. The patient’s temperature, vital signs, blood loss, coagulation factors, and neurologic status are monitored throughout the procedure.

During the surgery, the anesthesiologist and the surgeon maintain verbal communication and conduct a brief, formalized communication hourly per protocol. During this interaction, the anesthesiologist reports vital signs, cumulative blood loss, lab results (including coagulation factor levels), and any other potential concerns. Likewise, the surgeon reports observed blood loss, clotting, and any unusual anatomic findings that may affect the course of the procedure.

The anesthesiologist has a strict protocol regarding the patient’s temperature, drawing of labs, and monitoring for thresholds to transfuse blood or replete coagulation factors.

Our experience shows that patients have a propensity to develop a consumptive coagulopathy approximately 6 hours into the surgical procedure. Therefore, at the 6-hour mark, specific focus is directed to the patient’s coagulation factor levels and cumulative blood loss, and protocol-driven corrections are implemented.

Postoperative care
Postoperatively, all high-risk spine patients are accompanied by the anesthesiologist during routine transfer to the neurosurgical intensive care unit (ICU). This is done so the anesthesiologist can meet and report directly to the critical care physician and unit nurse. The patient’s internist is also notified of the patient’s arrival in the ICU.

During the patient’s stay in the ICU, coagulation factors are monitored and corrected regularly to minimize any episodes of hypotension or cardiopulmonary compromise. Intensivists following these patients wean the patient from the ventilator according to the protocol. The protocol is maintained as the patient is transferred to the floor and continues until discharge.

Excellent communication is a priority during any transfer of the patient between services or location within the hospital, and when transitioning the patient back to the care of his or her internist upon discharge.

Preliminary results
Stratifying certain spine patients as high-risk patients has become an important part of our surgical plan. Identifying and optimizing modifiable risk factors can decrease the risk of surgical morbidity and mortality. A standard protocol involving a multidisciplinary approach to high-risk patients may ultimately lead to improved patient outcomes. Although data collection and analysis is ongoing, preliminary data of patients assigned to the high-risk spine protocol have shown an improvement in clinical outcomes.

Disclosure information: Dr. Schafer—AAOS Now; Journal of Bone & Joint Surgery–American; Spine; Dr. Murray—no conflicts.

Michael F. Schafer, MD, is professor of orthopaedic surgery at Northwestern University-Feinberg School of Medicine, and chair of the department of orthopaedic surgery at Northwestern Memorial Hospital. Michael R. Murray, MD, is a resident in orthopaedic surgery at Northwestern University-Feinberg School of Medicine.

References:

1. Ganocy TK, Ohtomo M, Boachie-Adjei O: Complication rates for combined anterior-posterior adult deformity surgery. SRS Meeting, Quebec City, Quebec, Canada, 2003.
2. Lapp MA, Bridwell KH, Lenke LG, et al: Long-term complications in adult spinal deformity patients having combined surgery: A comparison of primary to revision patients. Spine 2001;26:973–983.
3. Swank S, Lonstein JE, Moe JH, et al: Surgical treatment of adult scoliosis: A review of two hundred and twenty-two cases. J Bone Joint Surg Am 1981;63:268–287.
4. Halpin RJ, Sugrue PA, Gould RW, et al: Standardizing care for high-risk patients in spine surgery: The Northwestern High-Risk Spine Protocol. Spine 2010;35:2232–2238.