This study is a randomized controlled trial that will evaluate the effect of non-invasive auricular vagal nerve stimulation on inflammatory markers, glycemic control, postoperative pain, and inflammation-related clinical outcomes after long-segment spinal fusion surgeries when compared to current accepted management.
Long-segment spinal fusions are effective interventions to relieve pain, neurological compromise, or disability related to a variety of causes of advanced spinal degeneration or spinal deformity. Despite advancements in minimally invasive spine surgery, revision of prior instrumentation, correction of coronal or sagittal imbalance, bony decompression, and multilevel arthrodesis often must be performed via open surgery. While these procedures can produce excellent results with regards to postoperative alignment, neural decompression, and functional improvement, they are long and invasive cases requiring large incisions and extensive soft tissue dissection and osseous manipulation. As such, postoperative adverse events or complications are common (e.g., DVT/PE, wound healing problems, infection, nerve stretch injury, etc.). These patients almost universally experience significant postoperative pain, require postoperative rehabilitation, and are at high-risk for hospital readmissions. Moreover, the sterile trauma from long-segment spinal surgeries is a tremendous systemic inflammatory stimulus that yields downstream sequelae such as hyperglycemia, elevated inflammatory markers (e.g. cytokines), signs of microvascular ischemia, and other stress-related outcomes. Attempts to control this inflammation and reduce the adverse effects of these surgeries are lacking, particularly with respect to non-pharmacologic options. Vagal nerve stimulation (VNS) is a promising emerging modality by which the body's systemic inflammatory response may be attenuated. Importantly, VNS may be successfully applied via noninvasive auricular stimulation. This technique has been trialed as non-pharmacologic pain control adjunct after multiple types of surgeries or painful medical events, but none as traumatic as long-segment spinal fusion. It also has been shown to yield substantial anti-inflammatory effects in numerous animal models. Furthermore, auricular VNS has been extensively studied at Washington University School of Medicine in multiple neurological conditions, including aneurysmal subarachnoid hemorrhage, acute ischemic stroke, and intraparenchymal hemorrhage. The use of noninvasive VNS devices has been shown to be an intervention that is safely administered and does not cause undue distress to patients. Given these promising aspects of VNS, Washington University's particular interest in this treatment modality, and the unmet postoperative care needs for long-segment spinal fusion patients, the investigators propose prospectively studying the effects of auricular VNS in a population of patients at Barnes-Jewish Hospital who have undergone long-segment fusion surgeries. The investigators hypothesize that perioperative VNS will mitigate the systemic inflammatory reaction in these patients as demonstrated by reduced inflammatory markers (both direct and indirect) and improved inflammatory-mediated clinical outcomes. This study will be a randomized controlled trial assessing differences between accepted perioperative care plus auricular VNS (the intervention) as compared to accepted perioperative care plus a sham stimulus. The VNS device will be a noninvasive stimulator applied to the left ear to stimulate the auricular branch of the vagus nerve. All patients will be fitted with the device, and the sham stimulus will not receive the required therapeutic stimulation through the device. Patients will receive stimulation twice on the day of surgery followed by twice daily during the duration of their postoperative hospital admission. Relevant inflammatory cytokines, laboratory tests, pain scores, clinical outcomes, and imaging studies will be obtained for each patient. Post-hospital disposition, delayed adverse outcomes, and hospital readmissions will also be tracked after discharge.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
50
Transcutaneous auricular vagal nerve stimulation
Transcutaneous auricular vagal nerve stimulator applied without utilizing stimulating current.
Washington University School of Medicine
St Louis, Missouri, United States
RECRUITINGInflammatory cytokine levels
The levels of 4 different inflammatory cytokines will be measured: interleukin-6 (IL-6), IL-1, IL-10, and tumor necrosis factor alpha (TNF-a) (all measured in pg/ml). Blood for these tests will be drawn preoperatively, postoperatively, on postop day 3, and postop day 6 (or time of discharge).
Time frame: 5-10 days (depending on hospital admission length)
Pain scores
Patient pain levels will be assessed twice daily using the visual analogue scale (VAS), a validated pain reporting scale that uses a 100-millimeter horizontal line with anchors at "no pain" (0) and "worst possible pain" (100). Patients draw a line along this spectrum to signify their pain level. Higher distance along the spectrum in a left-to-right direction indicates higher pain.
Time frame: 5-10 days (depending on hospital admission length)
blood glucose levels
Glucose measurements will be obtained multiple times daily via bedside point-of-care testing as well as through daily CMP labs (in mg/dL).
Time frame: 5-10 days (depending on hospital admission length)
Postoperative adverse events/complications
Investigators will track the incidence of postoperative adverse events or complications, including temporary radiculopathy or nerve stretch injury, deep vein thrombosis (DVT), pulmonary embolism (PE), acute kidney injury (AKI), ileus, wound healing problems, hospital delirium, transfusion reactions, and infections. All patients will receive screening lower extremity doppler (LED) studies before surgery and at time of hospital discharge.
Time frame: 5-10 days (depending on hospital admission length)
Secondary markers of inflammation
Daily laboratory studies that serve as surrogate markers for the body's degree of systemic inflammation will be obtained. This includes labs such as CRP, cortisol, creatinine, and troponin (all in mg/dL)
Time frame: 5-10 days (depending on hospital admission length)
Post-hospitalization disposition
Investigators will track patients' post-hospitalization disposition (e.g. home versus inpatient rehabilitation).
Time frame: 5-10 days (depending on hospital admission length)
Heart rate
Investigators will continuously monitor patients' heart rates to capture incidences of bradycardia that may be associated with the VNS intervention.
Time frame: Time Frame: 5-10 days (depending on hospital admission length)
Opioid usage
Patients' daily opioid usage will be recorded while hospitalized. Usage will be converted to morphine milligram equivalents (MME).
Time frame: 5-10 days (depending on hospital admission length)
Insulin requirements
Insulin requirements (units insulin) for patients during their hospital stay will be recorded.
Time frame: 5-10 days (depending on hospital admission length)
Erythrocyte sedimentation rate (ESR)
Postoperative ESR will be measured daily (in mm/hr) to assess systemic inflammation.
Time frame: 5-10 days (depending on hospital admission length)
D-dimer levels
D-dimer levels will be obtained postoperatively every other day (in microgram/mL)
Time frame: 5-10 days (depending on hospital admission length)]
Hospital admission length
Length of patient hospital stay after surgery will be recorded.
Time frame: 5-10 days (depending on hospital admission length)
Blood pressure
Tracking of blood pressure and temperature will allow investigators to evaluate the potential influence of VNS on blood pressure control for hypertensive patients and to determine if any hypotensive events are associated with the intervention.
Time frame: 5-10 days (depending on hospital admission length)]
Readmission rates
The incidence of hospital readmission within 30 days and 60 days will be recorded (yes versus no readmissions).
Time frame: 60 days postoperatively
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