Major spinal surgery procedures have increased significantly 1) 2) for three main reasons: the increased age demographic of the general population, the introduction of minimally invasive methods including percutaneous procedures, and improved outcomes including reduced hospital stay and return to desirable lifestyle. Lumbar and cervical fusion are the main reported procedures on the spine and these numbers seems to be significantly increase because of life style variations 3) 4).
Although spine fusions are now considered minimally invasive techniques, the aggregate costs related to these surgeries has increased since the complexity of spinal involvement and number of levels to be fused have increased 5).
A metaanalysis on the effectiveness of minimally invasive techniques for lumbar spinal stenosis has revealed that there was no difference in terms of improved outcome for the most commonly used surgical techniques 6). Other important factors to be considered in complex spinal surgeries include length of the procedure and anaesthesia time, prolonged prone positioning and blood loss which can contributors to postoperative adverse events.
One of the medical fields that has intensively utilized the most advanced technologies is complex spinal surgery. A multitude of novel types of instrumentation, implants, navigation and biologics have recently become available for the use in complex spine surgery 7). However, critics point out that technologically advanced treatments may offer little or no clinical benefit compared to traditional treatment strategies 8).
Predictive clinical decision support is having an increasing impact in the field of risk stratification in complex spine surgery. Researchers are building accurate multivariate predictive models that can be applied to clinical practice in the form of decision support systems (DSS). Bekelis et al. created a statistical model to predict complications in spine surgery based on data from 13,660 patient cases. The model’s outcome variables included 30-day postoperative risk of stroke, myocardial infarction (MI), wound infection, urinary tract infection (UTI), death, deep vein thrombosis (DVT), pulmonary embolism, and unplanned return to surgery. Predictors were preoperative patient characteristics. The model was able to successfully discriminate between cases that did and did not experience complications. Areas under the receiver operating characteristics curves for each of the outcome variables ranged from moderate to high 9).
In a retrospective cohort analysis, we considered adults who had complex spine surgery between January 2005 and September 2014 at the Cleveland Clinic Main Campus. Our primary outcome was postoperative estimated glomerular filtration rate. Secondarily, we evaluated renal function using Acute Kidney Injury Network criteria. We obtained data for 1814 surgeries, including 689 patients (38%) who were given intraoperative vasopressors infusion for ≥30 minutes and 1125 patients (62%) who were not. Five hundred forty patients with and 540 patients without vasopressor infusions were well matched across 32 potential confounding variables.
In matched patients, vasopressor infusions lasted an average of 173 ± 100 minutes (SD) and were given a median dose (1st quintile, 3rd quintile) of 3.4-mg (1.5, 6.7 mg) phenylephrine equivalents. Mean arterial pressure and the amounts of hypotension were similar in each matched group. The postoperative difference in mean estimated glomerular filtration rate in patients with and without vasopressor infusions was only 0.8 mL/min/1.73 m (95% CI, -0.6 to 2.2 mL/min/1.73 m) (P = .28). Intraoperative vasopressor infusion was also not associated with increased odds of augmented acute kidney injury stage.
Clinicians should not avoid typical perioperative doses of vasopressors for fear of promoting kidney injury. Tolerating hypotension to avoid vasopressor use would probably be a poor strategy 10).