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.

Hypoxemia Within the First 3 Postoperative Days Is Associated With Increased 1-Year Postoperative Mortality After Adjusting for Perioperative Opioids and Other Confounders.

BACKGROUND: Postoperative hypoxemia (POH) is common and primarily treated with temporary oxygen supplementation. Because the clinical impact of POH is sometimes presumed as minor, efforts to better understand and minimize it have been limited. Here, we hypothesized that, after adjusting for opioids received perioperatively and other confounders, the frequency of POH events (POH%) reported within the first 3 postoperative days (PODs) is associated with increased postoperative 1-year mortality. METHODS: With prior institutional review board (IRB) approval, the Epic Clarity database was queried for all adult inpatient anesthesia encounters performed at our health system (1 academic and 2 community hospitals) from January 1, 2012 to March 31, 2016. Patients with multiple hospitalizations or subsequent surgeries within the same hospitalization were excluded. We classified patients based on the presence (POH) or not (No-POH) of ≥1 documented peripheral saturation of oxyhemoglobin (SpO2) ≤85% event of any duration occurring between the discharge from the postanesthesia care unit (PACU) until POD 3. Demographics, comorbidities, surgery duration, morphine milligram equivalents (OMME) administered perioperatively, respiratory therapies, intensive care unit (ICU) admission, and hospital length of stay (LOS) were also collected. Logistic regression was used to characterize the association between POH and 1-year postoperative mortality after adjusting for perioperatively administered opioids and other confounding factors. RESULTS: A total of 43,011 patients met study criteria. At least 1 POH event was reported in 10,727 (24.9%) patients. Of these, 7179 (66.9%) had ≥1 hypoxemic event on POD 1, 5340 (49.8%) on POD 2, and 3455 (32.3%) on POD 3. Patients with ≥1 POH event, compared to No-POH patients, were older, had more respiratory and other comorbidities, underwent longer surgeries, received greater opioid doses on the day of surgery and POD 1, and received more continuous pulse oximetry monitoring. POH patients required more frequent postoperative oxygen therapy, noninvasive ventilation (NIV), intubation, and ICU admission. One-year postoperative mortality occurred in 4.4% of patients with ≥1 POH and 3.0% of No-POH patients (P < .001). After adjusting for confounding factors, for every 10% increase in the frequency of SpO2 ≤85% readings, the odds of postoperative 1-year mortality were 1.20 (95% confidence interval [CI], 1.11-1.29; P < .001). Perioperative opioids were not independently associated with increased 1-year mortality. CONCLUSIONS: After adjusting for perioperative opioids and other confounders, moderate/severe POH within the first 3 PODs was independently associated with increased 1-year postoperative mortality. Increased efforts should be directed to understand if efforts to detect and reduce POH lead to improved patient outcomes.

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.

Preoperatively Screened Obstructive Sleep Apnea Is Associated With Worse Postoperative Outcomes Than Previously Diagnosed Obstructive Sleep Apnea.

BACKGROUND: Obstructive sleep apnea (OSA) affects up to 26% of US adults, is often undiagnosed, and increases perioperative morbidity. We hypothesized that patients screened on the day of surgery as moderate/high risk for OSA (S-OSA) present similar perioperative respiratory complications, hospital use, and mortality than patients with previously diagnosed OSA (D-OSA). Second, we hypothesized that both OSA groups have more respiratory complications than No-OSA patients. METHODS: The electronic medical database from 1 academic and 2 community hospitals was retrospectively queried to identify adults undergoing nonemergent inpatient surgery (January 1, 2012, to December 31, 2014). Based on the day-of-surgery preoperative assessment and STOP-BANG (Snoring, Tiredness, Observed apnea during sleep, high blood Pressure, Body mass index >35, Age >50 years, thick Neck, Gender male) score, they were classified as D-OSA, S-OSA, or No-OSA. Perioperative respiratory events and interventions, hospital use, and mortality were measured. The primary outcome composite (adverse respiratory events [AREs]) included perioperative hypoxemic events and difficult airway management. Hypoxemic event was defined as peripheral saturation of oxygen (SpO2) <90% by continuous pulse oximetry for ≥3 minutes, or if validated and/or manually entered into the medical chart. Hypoxemia was classified as mild (lowest SpO2 86%-89%) or moderate/severe (lowest SpO2 ≤85%). Secondary outcomes included postoperative respiratory interventions, intensive care unit admission, hospital length of stay, and 30-day and 1-year all-cause mortality. Outcomes were compared using linear and logistic regression analyses. RESULTS: A total of 28,912 patients were assessed: 3432 (11.9%) D-OSA; 1546 (5.3%) S-OSA; and 23,934 (82.8%) No-OSA patients. At least 1 ARE was present in 68.0% of S-OSA; 71.0% of D-OSA; and 52.1% of No-OSA patients (unadjusted P < .001), primarily ≥1 moderate/severe hypoxemic event after discharge from the postanesthesia care unit (PACU; 39.9% in S-OSA; 39.5% in D-OSA; and 27.1% in No-OSA patients). S-OSA patients compared to D-OSA patients presented lower rates of moderate/severe hypoxemia in the PACU but similar intraoperatively and postoperatively, higher difficult mask ventilation rates, and similar difficult intubation reports. After adjusting for demographic, health, and surgical differences and hospital type, the likelihood of ≥1 ARE was not different in S-OSA and D-OSA patients (adjusted odds ratio 0.90 [99% confidence interval, 0.75-1.09]; P = .15). S-OSA patients compared to D-OSA patients had significantly increased postoperative reintubation, mechanical ventilation, direct intensive care unit admission after surgery, hospital length of stay, and 30-day all-cause mortality. CONCLUSIONS: Patients classified as S-OSA have similar rates of AREs to D-OSA patients, but increased postoperative respiratory interventions, hospital use, and 30-day all-cause mortality. These worse postoperative outcomes in S-OSA patients than D-OSA patients could reflect the lack of awareness and appropriate management of this bedside S-OSA diagnosis after PACU discharge. Multidisciplinary interventions are needed for these high-risk patients.

Success of Intubation Rescue Techniques after Failed Direct Laryngoscopy in Adults: A Retrospective Comparative Analysis from the Multicenter Perioperative Outcomes Group.

BACKGROUND: Multiple attempts at tracheal intubation are associated with mortality, and successful rescue requires a structured plan. However, there remains a paucity of data to guide the choice of intubation rescue technique after failed initial direct laryngoscopy. The authors studied a large perioperative database to determine success rates for commonly used intubation rescue techniques. METHODS: Using a retrospective, observational, comparative design, the authors analyzed records from seven academic centers within the Multicenter Perioperative Outcomes Group between 2004 and 2013. The primary outcome was the comparative success rate for five commonly used techniques to achieve successful tracheal intubation after failed direct laryngoscopy: (1) video laryngoscopy, (2) flexible fiberoptic intubation, (3) supraglottic airway as part of an exchange technique, (4) optical stylet, and (5) lighted stylet. RESULTS: A total of 346,861 cases were identified that involved attempted tracheal intubation. A total of 1,009 anesthesia providers managed 1,427 cases of failed direct laryngoscopy followed by subsequent intubation attempts (n = 1,619) that employed one of the five studied intubation rescue techniques. The use of video laryngoscopy resulted in a significantly higher success rate (92%; 95% CI, 90 to 93) than other techniques: supraglottic airway conduit (78%; 95% CI, 68 to 86), flexible bronchoscopic intubation (78%; 95% CI, 71 to 83), lighted stylet (77%; 95% CI, 69 to 83), and optical stylet (67%; 95% CI, 35 to 88). Providers most frequently choose video laryngoscopy (predominantly GlideScope [Verathon, USA]) to rescue failed direct laryngoscopy (1,122/1,619; 69%), and its use has increased during the study period. CONCLUSIONS: Video laryngoscopy is associated with a high rescue intubation success rate and is more commonly used than other rescue techniques.

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.

Implementation of a Standardized Protocol for Recurrent Laryngeal Nerve Monitoring Reduces False Negative Results During Neck Surgery: A Quality Control Case Study.

Recurrent laryngeal nerve (RLN) injury during neck surgery can cause significant morbidity related to vocal cord (VC) dysfunction. VC electromyography (EMG) is used to aid in the identification of the RLN and can reduce the probability of inadvertent surgical injury. Errors in the placement of specialized EMG endotracheal tubes (ETT) can result in unreliable signals, false-negative responses, or no response when stimulating the RLN. We describe a novel educational protocol developed to optimize uniformity in the placement of ETTs to improve the reliability of RLN monitoring. An intraoperative neuromonitoring database was queried for all neck surgeries requiring RLN monitoring. Data points extracted for all cases requiring EMG monitoring for neck procedures. Free running and stimulated EMG were monitored and continuously recorded by a certified technologist. Alerts were compared between 2013-14 and 2015-18 using a two-sample test of proportions. Significant reductions in alerts were demonstrated after protocol implementation (7.5% pre-implementation to 2.1% post). Alerts were compared between 2013-14 (overall alert rate of 1.8%, pre-implementation period) and 2015-18 (overall alert rate of 2.8%, post-implementation period). Protocolization for placement of EMG-ETT improved accuracy in EMG monitoring. In the follow-up cohort of 1,080 patients, use of this protocol continued to reduce the rate of alerts related to ETT malposition, confirming the sustainability of this intervention through routine education. The risk of nerve injury is reduced when the rate of alerts is minimized. Scheduled or continuous protocol education of anesthesia personnel should continue to ensure compliance with protocol.

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.

Transient cardiac asystole during vagus nerve stimulator implantation: A case report.

Background: Vagal nerve stimulation (VNS) is a Food and Drug Administration approved therapy for seizures with a suggested mechanism of action consisting of cortical desynchronization, facilitated through broad release of inhibitory neurotransmitters in the cortex and brainstem. The vagus nerve contains visceral afferents that transmit sensory signals centrally, from locations that include the heart and the aorta. Although the vagus nerve serves a role in cardiac function, electrical stimulation with VNS has rarely resulted in adverse cardiac events. Here, we report a case of a cardiac event during left-sided VNS implantation. Case Description: A 22-year-old male with an 8-year history of absence seizures and a 3-year history of medically refractory generalized tonic-clonic seizure was planned for surgical implantation of a VNS device. In the operating room, the patient underwent left-sided VNS implantation. An initial impedance check was performed with subsequent wound irrigation; following a few seconds of irrigation, a 5 s complete cardiac pause was noted. A repeated impedance check, which included turning on the stimulation, did not replicate the cardiac pause. No further pauses or cardiac events were noted and the case continued to completion without issue. The patient was later activated without any further complications. Conclusion: This report describes the initiation of a cardiac event, unlikely resulting from VNS, but instead time linked to intraoperative irrigation directly on the vagus nerve.

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.

Multimodality monitoring of the central nervous system using motor-evoked potentials.

PURPOSE OF REVIEW: This review was conducted to examine the role of motor-evoked potential monitoring in spine and central nervous system surgery to determine whether other monitoring modalities such as the wake-up test or somatosensory-evoked potentials can be eliminated. RECENT FINDINGS: The current literature suggests that motor-evoked potential, despite some advantages, still requires that other monitoring modalities such as somatosensory-evoked potentials or electromyography be used to provide optimal monitoring. SUMMARY: The literature supports the use of multimodality monitoring using all of the electrophysiological techniques that can provide intraoperative information about the neural structures at risk during the surgery.

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.