OBJECTIVE: Intraoperative neuromonitoring may be valuable for predicting postoperative neurological complications, and transcranial motor evoked potentials (TcMEPs) are the most reliable monitoring modality with high sensitivity. One of the most frequent problems of TcMEP monitoring is the high rate of false-positive alerts, also called “anesthetic fade.” The purpose of this study was to clarify the risk factors for false-positive TcMEP alerts and to find ways to reduce false-positive rates.METHODS: The authors analyzed 703 patients who underwent TcMEP monitoring under total intravenous anesthesia during spinal surgery within a 7-year interval. They defined an alert point as final TcMEP amplitudes ≤ 30% of the baseline. Variations in body temperature (maximum − minimum body temperature during surgery) were measured. Patients with false-positive alerts were classified into 2 groups: a global group with alerts observed in 2 or more muscles of the upper and lower extremities, and a focal group with alerts observed in 1 muscle.RESULTS: False-positive alerts occurred in 100 cases (14%), comprising 60 cases with global and 40 cases with focal alerts. Compared with the 545 true-negative cases, in the false-positive cases the patients had received a significantly higher total propofol dose (1915 mg vs 1380 mg; p < 0.001). In the false-positive cases with global alerts, the patients had also received a higher mean propofol dose than those with focal alerts (4.5 mg/kg/hr vs 4.2 mg/kg/hr; p = 0.087). The cutoff value of the total propofol dose for predicting false-positive alerts, with the best sensitivity and specificity, was 1550 mg. Multivariate logistic analysis revealed that a total propofol dose > 1550 mg (OR 4.583; 95% CI 2.785–7.539; p < 0.001), variation in body temperature (1°C difference; OR 1.691; 95% CI 1.060–2.465; p < 0.01), and estimated blood loss (500-ml difference; OR 1.309; 95% CI 1.155–1.484; p < 0.001) were independently associated with false-positive alerts.CONCLUSIONS: Intraoperative total propofol dose > 1550 mg, larger variation in body temperature, and greater blood loss are independently associated with false-positive alerts during spinal surgery. The authors believe that these factors may contribute to the false-positive global alerts that characterize anesthetic fade. As it is necessary to consider multiple confounding factors to distinguish false-positive alerts from true-positive alerts, including variation in body temperature or ischemic condition, the authors argue the importance of a team approach that includes surgeons, anesthesiologists, and medical engineers.

Transcranial motor evoked potential (TcMEP) monitoring may be valuable for predicting postoperative neurological complications with a high sensitivity and specificity, but one of the most frequent problems is the high false-positive rate. The purpose of this study was to clarify the differences in the risk factors for false-positive TcMEP alerts seen when performing surgery in patients with pediatric scoliosis and adult spinal deformity and to identify a method to reduce the false-positive rate. The authors retrospectively analyzed 393 patients (282 adult and 111 pediatric patients) who underwent TcMEP monitoring while under total intravenous anesthesia during spinal deformity surgery. They defined their cutoff (alert) point as a final TcMEP amplitude of ≤ 30% of the baseline amplitude. Patients with false-positive alerts were classified into one of two groups: a group with pediatric scoliosis and a group with adult spinal deformity. There were 14 cases of false-positive alerts (13%) during pediatric scoliosis surgery and 62 cases of false-positive alerts (22%) during adult spinal deformity surgery. Compared to the true-negative cases during adult spinal deformity surgery, the false-positive cases had a significantly longer duration of surgery and greater estimated blood loss (both p < 0.001). Compared to the true-negative cases during pediatric scoliosis surgery, the false-positive cases had received a significantly higher total fentanyl dose and a higher mean propofol dose (0.75 ± 0.32 mg vs 0.51 ± 0.18 mg [p = 0.014] and 5.6 ± 0.8 mg/kg/hr vs 5.0 ± 0.7 mg/kg/hr [p = 0.009], respectively). A multivariate logistic regression analysis revealed that the duration of surgery (1-hour difference: OR 1.701; 95% CI 1.364–2.120; p < 0.001) was independently associated with false-positive alerts during adult spinal deformity surgery. A multivariate logistic regression analysis revealed that the mean propofol dose (1-mg/kg/hr difference: OR 3.117; 95% CI 1.196–8.123; p = 0.020), the total fentanyl dose (0.05-mg difference; OR 1.270; 95% CI 1.078–1.497; p = 0.004), and the duration of surgery (1-hour difference: OR 2.685; 95% CI 1.131–6.377; p = 0.025) were independently associated with false-positive alerts during pediatric scoliosis surgery. Longer duration of surgery and greater blood loss are more likely to result in false-positive alerts during adult spinal deformity surgery. In particular, anesthetic doses were associated with false-positive TcMEP alerts during pediatric scoliosis surgery. The authors believe that false-positive alerts during pediatric scoliosis surgery, in particular, are caused by “anesthetic fade.”

Elderly patients with hip fracture are at risk for cardiac complications. N-terminal pro-brain type natriuretic peptide (NT-proBNP) has been shown to predict cardiac complications in surgical patients; however, to our knowledge, only two studies have evaluated the utility of this test in patients with hip fracture. We believe it is important to assess a more accurate cutoff value of NT-proBNP with exclusion of patients with renal failure. To assess the association between preoperative NT-proBNP and cardiac complications after hip fracture surgery. We performed 450 surgical procedures in patients with hip fractures between January 2011 and December 2014. Exclusion criteria were renal dysfunction and inadequate laboratory tests. The final study population consisted of 328 patients (mean age, 83 years; 80% women). Preoperatively, measurement of NT-proBNP level was performed. The primary endpoint was the occurrence of cardiac complications within 14 days after surgery based on a chart review. The predictive value of NT-proBNP was assessed using multivariate logistic regression analysis, controlling for relevant confounding variables such as age, gender, body weight, and renal function; we also performed receiver operating characteristic (ROC) curve analysis. Postoperative cardiac complications were encountered in 7% of patients (24 of 328). The median preoperative NT-proBNP level was higher in patients with complications than in those without (1090 [interquartile range, 614-3191 pg/mL] vs 283 pg/mL [interquartile range, 137-507 pg/mL], p < 0.001). The cutoff level of NT-proBNP determined by ROC curve analysis was 600 pg/mL, with a sensitivity, specificity, positive predictive value, and negative predictive value of 79%, 81%, 25%, and 98%, respectively, and the area under the ROC curve was 0.87 (95% CI, 0.80-0.94; p < 0.001). After controlling for potentially relevant confounding variables, we found a preoperative NT-proBNP greater than 600 pg/mL was associated with an increased risk of cardiac complications (odds ratio, 13; 95% CI, 4-38; p < 0.001) compared with those with NT-proBNP less than 600 pg/mL. Preoperative NT-proBNP greater than 600 pg/mL is independently associated with postoperative cardiac complications in patients with hip fracture without renal dysfunction. NT-proBNP measurement provides additional information and is clinically useful for predicting cardiac complications during the early phase after hip fracture surgery. Future studies might develop a simple index for prediction of postoperative cardiac complication including cutoff values of NT-proBNP. Level III, diagnostic study.

Study design: Retrospective longitudinal cohort study. Objective: To investigate postoperative medical complications in patients with malnutrition after cervical posterior surgery. Methods: A total of 256 patients were participated and divided into PNI < 50 group (group L) or PNI ≥ 50 (group H). Patient data, preoperative laboratory data, surgical data, hospitalization data, JOA score, complication data were measured. Results: Group L and group H were 127 and 129 patients, each PNI was L: 44.8 ± 4.3, H: 54.6 ± 4.0, P < 0.01. There was significant difference in mean age (L: 72.2 years vs H: 64.8 years, P < 0.01), BMI (23.1 vs 24.7, P < 0.01), serum albumin (L: 3.9 ± 0.4 g/dl vs H: 4.4 ± 0.3 g/dl, P < 0.01), total lymphocyte count (L: 1.3 ± 0.5 10³/µL vs H: 2.1 ± 0.7 10³/μL, P < 0.01), hospital stay (L: 25.0 days vs H: 18.8 days, P < 0.05), discharge to home (87.5% vs 57.5%, P < 0.01), delirium (L: 15.9% vs H: 3.9%, P < 0.01), medical complications (L: 25.2% vs H: 7.0%, P < 0.01), pre- and post- operative JOA score (L: 11.3 ± 2.8 vs H: 12.4 ± 2.6, P < 0.01; L: 13.3 ± 3.0 vs H: 14.1 ± 2.4, P = 0.02). Multiple logistic regression analysis showed that significant risk factors for medical complications were PNI<50 (P = 0.024, odds ratio [OR] 2.746, 95% confidence interval [CI] 1.143–6.600) and age (P = 0.005, odds ratio [OR] 1.064, 95% confidence interval [CI] 1.020–1.111). Conclusion: Medical complications are significantly higher in patients with PNI < 50 and higher age. The results showed that PNI is a good indicator for perioperative medical complications in cervical posterior surgery. Improvement of preoperative nutritional status is important to avoid medical complications. Level of evidence: 3

OBJECTIVE: Surgical site infection (SSI) after posterior spinal surgery is one of the severe complications that may occur despite administration of prophylactic antibiotics and the use of intraoperative aseptic precautions. The use of intrawound vancomycin powder for SSI prevention is still controversial, with a lack of high-quality and large-scale studies. The purpose of this retrospective study using a propensity score–matched analysis was to clarify whether intrawound vancomycin powder prevents SSI occurrence after spinal surgery. METHODS: The authors analyzed 1261 adult patients who underwent posterior spinal surgery between 2010 and 2018 (mean age 62.3 years; 506 men, 755 women; follow-up period at least 1 year). Baseline and surgical data were assessed. After a preliminary analysis, a propensity score model was established with adjustments for age, sex, type of disease, and previously reported risk factors for SSI. The SSI rates were compared between patients with intrawound vancomycin powder treatment (vancomycin group) and those without (control group). RESULTS: In a preliminary analysis of 1261 unmatched patients (623 patients in the vancomycin group and 638 patients in the control group), there were significant differences between the groups in age (p = 0.041), body mass index (p = 0.013), American Society of Anesthesiologists classification (p < 0.001), malnutrition (p = 0.001), revision status (p < 0.001), use of steroids (p = 0.019), use of anticoagulation (p = 0.033), length of surgery (p = 0.003), estimated blood loss (p < 0.001), and use of instrumentation (p < 0.001). There was no significant difference in SSI rates between the vancomycin and control groups (21 SSIs [3.4%] vs 33 SSIs [5.2%]; OR 0.640, 95% CI 0.368–1.111; p = 0.114). Using a one-to-one propensity score–matched analysis, 444 pairs of patients from the vancomycin and control groups were selected. There was no significant difference in the baseline and surgical data, except for height (p = 0.046), between both groups. The C-statistic for the propensity score model was 0.702. In the score-matched analysis, 12 (2.7%) and 24 (5.4%) patients in the vancomycin and control groups, respectively, developed SSIs (OR 0.486, 95% CI 0.243–0.972; p = 0.041). There were no systemic complications related to the use of vancomycin. CONCLUSIONS: The current study showed that intrawound vancomycin powder was useful in reducing the risk of SSI after posterior spinal surgery by half, without adverse events. Intrawound vancomycin powder use is a safe and effective procedure for SSI prevention.