Toxicology Screening Testing in Patients Undergoing Spine Surgery: A Prospective Observational Pilot Study.

BACKGROUND: Chronic opioid use and polypharmacy are commonly seen in chronic pain patients presenting for spine procedures. Substance abuse and misuse have also been reported in this patient population. Negative perioperative effects have been found in patients exposed to chronic opioid, alcohol, and recreational substances. Toxicology screening testing (TST) in the perioperative period provides useful information for adequate preoperative optimization and perioperative planning. METHODS: We designed a pilot study to understand this population's preoperative habits including accuracy of self-report and TST-detected prescribed and unprescribed medications and recreational substances. We compared the results of the TST to the self-reported medications using Spearman correlations. RESULTS: Inconsistencies between TST and self-report were found in 88% of patients. Spearman correlation was 0.509 between polypharmacy and intraoperative propofol use, suggesting that propofol requirement increased as the number of substances used increased. CONCLUSIONS: TST in patients presenting for spine surgery is a useful tool to detect substances taken by patients because self-report is often inaccurate. Discrepancies decrease the opportunity for preoperative optimization and adequate perioperative preparation.

Preoperative Risk and the Association between Hypotension and Postoperative Acute Kidney Injury.

BACKGROUND: Despite the significant healthcare impact of acute kidney injury, little is known regarding prevention. Single-center data have implicated hypotension in developing postoperative acute kidney injury. The generalizability of this finding and the interaction between hypotension and baseline patient disease burden remain unknown. The authors sought to determine whether the association between intraoperative hypotension and acute kidney injury varies by preoperative risk. METHODS: Major noncardiac surgical procedures performed on adult patients across eight hospitals between 2008 and 2015 were reviewed. Derivation and validation cohorts were used, and cases were stratified into preoperative risk quartiles based upon comorbidities and surgical procedure. After preoperative risk stratification, associations between intraoperative hypotension and acute kidney injury were analyzed. Hypotension was defined as the lowest mean arterial pressure range achieved for more than 10 min; ranges were defined as absolute (mmHg) or relative (percentage of decrease from baseline). RESULTS: Among 138,021 cases reviewed, 12,431 (9.0%) developed postoperative acute kidney injury. Major risk factors included anemia, estimated glomerular filtration rate, surgery type, American Society of Anesthesiologists Physical Status, and expected anesthesia duration. Using such factors and others for risk stratification, patients with low baseline risk demonstrated no associations between intraoperative hypotension and acute kidney injury. Patients with medium risk demonstrated associations between severe-range intraoperative hypotension (mean arterial pressure less than 50 mmHg) and acute kidney injury (adjusted odds ratio, 2.62; 95% CI, 1.65 to 4.16 in validation cohort). In patients with the highest risk, mild hypotension ranges (mean arterial pressure 55 to 59 mmHg) were associated with acute kidney injury (adjusted odds ratio, 1.34; 95% CI, 1.16 to 1.56). Compared with absolute hypotension, relative hypotension demonstrated weak associations with acute kidney injury not replicable in the validation cohort. CONCLUSIONS: Adult patients undergoing noncardiac surgery demonstrate varying associations with distinct levels of hypotension when stratified by preoperative risk factors. Specific levels of absolute hypotension, but not relative hypotension, are an important independent risk factor for acute kidney injury.

Neostigmine Versus Sugammadex for Reversal of Neuromuscular Blockade and Effects on Reintubation for Respiratory Failure or Newly Initiated Noninvasive Ventilation: An Interrupted Time Series Design.

BACKGROUND: Pulmonary complications related to residual neuromuscular blockade lead to morbidity and mortality. Using an interrupted time series design, we tested whether proportions of reintubation for respiratory failure or new noninvasive ventilation were changed after a system-wide transition of the standard reversal agent from neostigmine to sugammadex. METHODS: Adult patients undergoing a procedure with general anesthesia that included pharmacologic reversal of neuromuscular blockade and admission ≥1 night were eligible. Groups were determined by date of surgery: August 15, 2015 to May 10, 2016 (presugammadex), and August 15, 2016 to May 11, 2017 (postsugammadex). The period from May 11, 2016 to August 14, 2016 marked the institutional transition (washout/wash-in) from neostigmine to sugammadex. The primary outcome was defined as a composite of reintubation for respiratory failure or new noninvasive ventilation. Event proportions were parsed into 10-day intervals in each cohort, and trend lines were fitted. Segmented logistic regression models appropriate for an interrupted time series design and adjusting for potential confounders were utilized to evaluate the immediate effect of the implementation of sugammadex and on the difference between preintervention and postintervention slopes of the outcomes. Models containing all parameters (full) and only significant parameters (parsimonious) were fitted and are reported. RESULTS: Of 13,031 screened patients, 7316 patients were included. The composite respiratory outcome occurred in 6.1% of the presugammadex group and 4.2% of the postsugammadex group. Adjusted odds ratio (OR) and 95% confidence intervals (CIs) for the composite respiratory outcome were 0.795 (95% CI, 0.523-1.208) for the immediate effect of intervention, 0.986 (95% CI, 0.959-1.013) for the difference between preintervention and postintervention slopes in the full model, and 0.667 (95% CI, 0.536-0.830) for the immediate effect of the intervention in the parsimonious model. CONCLUSIONS: The system-wide transition of the standard pharmacologic reversal agent from neostigmine to sugammadex was associated with a reduction in the odds of the composite respiratory outcome. This observation is supported by nonsignificant within-group time trends and a significant reduction in intercept/level from presugammadex to postsugammadex in a parsimonious logistic regression model adjusting for covariates.

Intraoperative Lung-Protective Ventilation Trends and Practice Patterns: A Report from the Multicenter Perioperative Outcomes Group.

BACKGROUND: The use of an intraoperative lung-protective ventilation strategy through tidal volume (TV) size reduction and positive end-expiratory pressure (PEEP) has been increasingly investigated. In this article, we describe the current intraoperative lung-protective ventilation practice patterns and trends. METHODS: By using the Multicenter Perioperative Outcomes Group database, we identified all general endotracheal anesthetics from January 2008 through December 2013 at 10 institutions. The following data were calculated: (1) percentage of patients receiving TV > 10 mL/kg predicted body weight (PBW); (2) median initial and overall TV in mL/kg PBW and; (3) percentage of patients receiving PEEP ≥ 5 cm H2O. The data were analyzed at 3-month intervals. Interinstitutional variability was assessed. RESULTS: A total of 330,823 patients met our inclusion criteria for this study. During the study period, the percentage of patients receiving TV > 10 mL/kg PBW was reduced for all patients (26% to 14%) and in the subpopulations of obese (41% to 25%), short stature (52% to 36%), and females (39% to 24%; all P values <0.001). There was a significant reduction in TV size (8.90-8.20 mL/kg PBW, P < 0.001). There was also a statistically significant but clinically irrelevant difference between initial and overall TV size (8.65 vs 8.63 mL/kg PBW, P < 0.001). Use of PEEP ≥ 5 cm H2O increased during the study period (25%-45%, P < 0.001). TV usage showed significant interinstitutional variability (P < 0.001). CONCLUSIONS: Although decreasing, a significant percentage of patients are ventilated with TV > 10 mL/kg PBW, especially if they are female, obese, or of short stature. The use of PEEP ≥ 5 cm H2O has increased significantly. Creating awareness of contemporary practice patterns and demonstrating the efficacy of lung-protective ventilation are still needed to optimize intraoperative ventilation.

Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy: a report from the multicenter perioperative outcomes group.

BACKGROUND: Research regarding difficult mask ventilation (DMV) combined with difficult laryngoscopy (DL) is extremely limited even though each technique serves as a rescue for one another. METHODS: Four tertiary care centers participating in the Multicenter Perioperative Outcomes Group used a consistent structured patient history and airway examination and airway outcome definition. DMV was defined as grade 3 or 4 mask ventilation, and DL was defined as grade 3 or 4 laryngoscopic view or four or more intubation attempts. The primary outcome was DMV combined with DL. Patients with the primary outcome were compared to those without the primary outcome to identify predictors of DMV combined with DL using a non-parsimonious logistic regression. RESULTS: Of 492,239 cases performed at four institutions among adult patients, 176,679 included a documented face mask ventilation and laryngoscopy attempt. Six hundred ninety-eight patients experienced the primary outcome, an overall incidence of 0.40%. One patient required an emergent cricothyrotomy, 177 were intubated using direct laryngoscopy, 284 using direct laryngoscopy with bougie introducer, 163 using videolaryngoscopy, and 73 using other techniques. Independent predictors of the primary outcome included age 46 yr or more, body mass index 30 or more, male sex, Mallampati III or IV, neck mass or radiation, limited thyromental distance, sleep apnea, presence of teeth, beard, thick neck, limited cervical spine mobility, and limited jaw protrusion (c-statistic 0.84 [95% CI, 0.82-0.87]). CONCLUSION: DMV combined with DL is an infrequent but not rare phenomenon. Most patients can be managed with the use of direct or videolaryngoscopy. An easy to use unweighted risk scale has robust discriminating capacity.

Intraoperative autologous transfusion of hemolyzed blood.

During two cases of lumbar spine surgery with instrumentation, we used intraoperative autologous transfusion (IAT), resulting in hemolysis during collection and hemoglobinuria and coagulation abnormalities after transfusion. Hemolysis during IAT collection can lead to hemoglobinuria and binding of nitric oxide, leading to vasoconstriction. The literature suggests that stroma from damaged cells and contact of the blood with the IAT device can lead to coagulation abnormalities and other morbidities, including adult respiratory distress syndrome.

Electrophysiologic monitoring during surgery to repair the thoraco-abdominal aorta.

Prevention of paraplegia during the repair of thoraco-abdominal aortic aneurysms and dissections present a substantial challenge to the operative team. The value of intraoperative electrophysiological monitoring (IOM) is to identify spinal cord ischemia that occurs during the procedure and guide the intraoperative management to reduce the risks of paralysis. The usefulness of IOM techniques requires an understanding of spinal cord blood flow and the spinal cord physiology, the surgical technique and their interaction. This paper will integrate these factors to review the laboratory and clinical experience with somatosensory evoked responses (SSEP) and motor evoked potentials (MEP) during thoraco-abdominal aorta surgery.

Neurophysiologic monitoring in neurosurgery.

This article focuses on the application of neurophysiologic monitoring in uniquely neurosurgical procedures. Neurophysiologic monitoring provides functional testing and mapping to identify neural structures. Once identified, the functionality of the central and peripheral nervous system areas at risk for neurosurgical injury can be monitored. It discusses the use of motor-evoked potentials, sensory evoked potentials, electromyography and electroencephalography to assess neurologic change.

Electrophysiologic monitoring in neurosurgery.

Electrophysiologic techniques have become common in the neurosurgical operating room. This article reviews the methods used for mapping neural structures or monitoring during surgery. Mapping methods allow identification of target structures for surgery, or for identifying structures to allow avoidance or plot safe pathways to deeper structures. Monitoring methods allow for surgery on nearby structures to warn of encroachment, thereby reducing unwanted injury.

Using EEG to monitor anesthesia drug effects during surgery.

The use of processed electroencephalography (EEG) using a simple frontal lead system has been made available for assessing the impact of anesthetic medications during surgery. This review discusses the basic principles behind these devices. The foundations of anesthesia monitoring rest on the observations of Guedel with ether that the depth of anesthesia relates to the cortical, brainstem and spinal effects of the anesthetic agents. Anesthesiologists strive to have a patient who is immobile, is unconscious, is hemodynamically stable and who has no intraoperative awareness or recall. These anesthetic management principles apply today, despite the absence of ether from the available anesthetic medications. The use of the EEG as a supplement to the usual monitoring techniques rests on the observation that anesthetic medications all alter the synaptic function which produces the EEG. Frontal EEG can be viewed as a surrogate for the drug effects on the entire central nervous system (CNS). Using mathematical processing techniques, commercial EEG devices create an index usually between 0 and 100 to characterize this drug effect. Critical aspects of memory formation occur in the frontal lobes making EEG monitoring in this area a possible method to assess risk of recall. Integration of processed EEG monitoring into anesthetic management is evolving and its ability to characterize all of the anesthetic effects on the CNS (in particular awareness and recall) and improve decision making is under study.

Monitoring of the brain and spinal cord.

IOM has become commonly used by many surgeons to enhance their intraoperative decision making and reduce the morbidity and mortality of selected procedures. The ability to perform these tests rests on the anesthesiologist's ability to provide the patient with an anesthetic plan that provides comfort and monitoring. When events occur, the anesthesiologist's knowledge and ability to manipulate the patient's physiologic condition become integral to the decision making. A good understanding of the neural anatomy, impact of physiology, and anesthetic medications can allow effective IOM and good team decision making when changes in IOM occur.