Comparison of the Conox (qCON) and Sedline (PSI) depth of anaesthesia indices to predict the hypnotic effect during desflurane general anaesthesia with ketamine.

Comparison of two depth of anesthesia indices, qCON (Conox) and PSI (Sedline), during desflurane sedation and their sensitivity to random ketamine boluses in patients undergoing routine surgery. The performance of desflurane and ketamine on both indices was analyzed for 11 patients, and the ketamine sensitivity was compared with another group of 11 patients under sevoflurane and propofol.The MOAA/S was used to determine sedation level and pain. Different boluses of ketamine ranging from 10 to 30 mg where randomly administered in both groups and the effect on the indexes were measured after 4 min.The indices were recorded during the whole surgery, and their correlations with the desflurane concentration and the discrimination between awake and anesthetized states were evaluated with the prediction probability statistic (Pk). The Pk values, mean (se), discriminating between awake and anesthetized states were 0.974(0.016) for the qCON and 0.962(0.0123) for the PSI, while the 1-Pk statistic for the qCON and the PSI with respect to the desflurane concentration were 0.927(0.016) and 0.918(0.018), respectively, with no statistically significant differences.The agreement between both depth of hypnosis parameters was assessed under the Bland-Altman plot and the Spearman correlation, rs = 0.57(p < 0.001).During the sevoflurane-propofol anesthesia, which served as a control group, both indices experienced a similar behavior with a no significant change of their median values after ketamine. However, during desflurane anesthesia the qCON index did not change significantly after ketamine administration, qCON (before = 33 (4), after = 30 (17); Wilcoxon, p = 0.89), while the PSI experienced a significant increase, PSI (before = 31(6), after = 39(16) Wilcoxon, p = 0.013).This study shows that qCON and PSI have similar performance under desflurane with good discrimination between the awake and anesthetized states. While both indices exhibited similar behavior under ketamine boluses under a sevoflurane-propofol anesthesia, the qCON index had a better performance under ketamine during desflurane anesthesia.

Optimizing the use of point of care testing devices for screening patients.

Point of Care Testing (POCT) devices are regularly used to improve clinical workflows in the hospital setting despite generally having inferior performance when compared to standardized laboratory analyzers. We describe a method to improve the efficacy of using a POCT device as a screening test when the laboratory values occur over a continuum and applied this methodology to the process of International Normalized Ratios (INR) screening on day of surgery. Following IRB approval, laboratory INR values on the day of surgery were extracted from the University of Vermont Medical Center operating room's electronic health record. Two separate theoretical POCT device values were simulated from the performance characterized by two prior publications (Jacobson and Hur). The sensitivities and specificities of the two theoretical devices were calculated over a range of values, in order detect an INR value greater or equal than 1.5 and 1.8. Subsequently, the percentage of the population with an INR value over each threshold was also calculated. Laboratory data from March 2008 to December 2016 were collected, and 9320 discrete INR values were compiled ranging from 0.8 to > 20. Two POCT devices were simulated using that dataset. The sensitivities and specificities over a range of values were determined, and the optimal cutoff values were identified for each device separately. Calculating the sensitivities and specificities over a range of values can optimize the clinical efficacy of a POCT device. By optimizing the use of POCT devices, hospitals may be able to improve clinical processes and reduce costs.

Pain monitor: reality or fantasy in ambulatory patients.

PURPOSE OF REVIEW: In an unconscious patient, there can be significant challenges to monitoring nociception and proper dosing of analgesic medications. The traditional measures of intraoperative nociception have poor sensitivity and specificity with little predictive value in postoperative outcomes such as postoperative pain, opioid-induced side effects, length of stay or incidence of opioid use disorder. To date, several monitoring modalities are in development to establish objective measures of the balance between nociception and analgesia with the goal of guiding anesthesiologists and improve patient outcomes. In this review, some of the most promising monitoring modalities are discussed with the most recent findings. RECENT FINDINGS: Multiple modalities are beginning to demonstrate utility compared with traditional care. Most, but not all, of these studies show decreased intraoperative opioid use and some show lower pain scores and opioid requirements in the postanesthesia care unit. SUMMARY: Recent evidence points to promising efficacy for these monitoring modalities; however, this field is in its infancy. More investigation is required to demonstrate differences in outcome compared with traditional care, and these differences need to be of sufficient import to achieve widespread adoption.

Improving patient safety during procedural sedation via respiratory volume monitoring: A randomized controlled trial.

STUDY OBJECTIVE: Assess the utility of a respiratory volume monitor (RVM) to reduce the incidence of low minute ventilation events in procedural sedation. DESIGN: Randomized control trial SETTING: Endoscopy suite PATIENTS: Seventy-three total patients (ASA Physical Status 1-3) undergoing upper endoscopies were analyzed. INTERVENTION: Patients were randomized into two groups using a computer generated randomization table: Control (n=41): anesthesia provider was unable to see the screen of the RVM; RVM (n=32): anesthesia provider had access to RVM data to assist with management of the case. MEASUREMENTS: Minute ventilation (MV), tidal volume, and respiratory rate were continuously recorded by the RVM. MV is presented as percent of Baseline MV (MVBaseline), defined during a 30s period of quiet breathing prior to sedation. We defined Low MV as MV<40% MVBaseline, and calculated the percentage of procedure spent with Low MV. Patients in the RVM group were stratified based on whether the anesthesiologist rated the RVM as "not useful", "somewhat useful", or "very useful" during the case. MAIN RESULTS: Control patients experienced twice as much Low MV compared to RVM patients (15.3±2.8% vs. 7.1±1.4%, P=0.020). The "not useful" (13.7±3.8%) group showed no improvement over the Control group (p=0.81). However, both the "very useful" (4.7±1.4%) and "somewhat useful" (4.9±1.7%) groups showed significant improvement over the "not useful" group (p<0.05). CONCLUSIONS: Patients in the Control group spent more than double the amount of time with Low MV compared to the RVM group. This difference became more pronounced when the anesthesiologist found the RVM useful for managing care, lending credibility to the usage of minute ventilation monitoring in procedural sedation.

Monitoring minute ventilation versus respiratory rate to measure the adequacy of ventilation in patients undergoing upper endoscopic procedures.

Endoscopic procedures performed under conscious sedation require careful monitoring of respiratory status to prevent adverse outcomes. This study utilizes a non-invasive respiratory volume monitor (RVM) that provides continuous real-time measurements of minute ventilation (MV), tidal volume and respiratory rate (RR) to assess the adequacy of ventilation during endoscopy. Digital respiratory traces were collected from 51 patients undergoing upper endoscopy with propofol sedation using an impedance-based RVM. Baseline MV for each patient was derived from a 30 s period of quiet breathing prior to sedation (MVBASELINE). Capnography data were also collected. Because RR from capnography was frequently unavailable, the RVM RR's were used for analysis. RR rate values were compared the MV measurements and sensitivity and specificity of RR to predict inadequate ventilation (MV <40 % MVBASELINE) were calculated. Initial analysis revealed that there is a weak correlation between an MV measurement and its corresponding RR measurement (r = 0.05). If MV is an actual indictor of respiratory performance, using RR as a proxy is grossly inadequate. Simulating a variety of RR alarm conditions [4-8 breaths/min (bpm)] showed that a substantial fraction of low MV measurements (MV <40 % MVBASELINE) went undetected (at 8 bpm, >70 % low MV measurements were missed; at 6 bpm, >82 % were missed; and at 4 bpm, >90 % were missed). A cut-off of 6 bpm had a sensitivity of only 18.2 %; while <40 % of all RR alarms would have coincided with a low MV (39.4 % PPV). Low RR measurements alone do not reflect episodes of low MV and are not sufficient for accurate assessment of respiratory status. RVM provides a new way to collect MV measurements which provide more comprehensive data than RR alone. Further work is ongoing to evaluate the use of MV data during procedural sedation.

Cognitive outcome after spinal anesthesia and surgery during infancy.

BACKGROUND: Observational studies on pediatric anesthesia neurotoxicity have been unable to distinguish long-term effects of general anesthesia (GA) from factors associated with the need for surgery. A recent study on elementary school children who had received a single GA during the first year of life demonstrated an association in otherwise healthy children between the duration of anesthesia and diminished test scores and also revealed a subgroup of children with "very poor academic achievement" (VPAA), scoring below the fifth percentile on standardized testing. Analysis of postoperative cognitive function in a similar cohort of children anesthetized with an alternative to GA may help to begin to separate the effects of anesthesia from other confounders. METHODS: We used a novel methodology to construct a combined medical and educational database to search for these effects in a similar cohort of children receiving spinal anesthesia (SA) for the same procedures. We compared former patients with a control population of students matched by grade, gender, year of testing, and socioeconomic status. RESULTS: Vermont Department of Education records were analyzed for 265 students who had a single exposure to SA during infancy for circumcision, pyloromyotomy, or inguinal hernia repair. Exposure to SA and surgery had no significant effect on the odds of children having VPAA. (mathematics: P = 0.18; odds ratio 1.50, confidence interval (CI), 0.83-2.68; reading: P = 0.55; odds ratio = 1.19, CI, 0.67-2.1). There was no relationship between duration of exposure to SA and surgery and performance on mathematics (P = 0.73) or reading (P = 0.57) standardized testing. There was a small but statistically significant decrease in reading and math scores in the exposed group (mathematics: P = 0.03; reading: P = 0.02). CONCLUSIONS: We found no link between duration of surgery with infant SA and scores on academic achievement testing in elementary school. We also found no relationship between infant SA and surgery with VPAA on elementary school testing, although the CIs were wide.

Increases in electroencephalogram and electromyogram variability are associated with an increased incidence of intraoperative somatic response.

BACKGROUND: sBIS, the variability of the Bispectral Index (BIS), sEMG, the variability of facial electromyogram power (EMG), and the Composite Variability Index (CVI) are 3 new measures of electroencephalogram and EMG variability. CVI is a single measure of the combined variability in BIS and EMG. We investigated whether increases in these variables are associated with intraoperative somatic responses. METHODS: This multicenter study included 120 patients undergoing elective, noncardiac surgery from 4 different sites. General anesthesia was maintained using propofol and remifentanil at 2 of the sites and sevoflurane and remifentanil at the 2 other sites. Propofol or sevoflurane was adjusted to maintain BIS between 45 and 60. Clinicians were blinded to CVI (v2.0) at all times, and remifentanil infusions were adjusted at the discretion of the clinician. The times of all intraoperative somatic events, defined as movement, grimacing, or eye opening, were recorded. Offline, the maintenance phase of each case was divided into consecutive, nonoverlapping, 10-minute segments. Segments were identified as containing a somatic event or containing no events. For each segment, mean sBIS, sEMG, and CVI and the heart rate (HR) range and mean arterial blood pressure range were calculated. To quantify how effectively each variable discriminated between somatic event segments and nonevent segments, we computed the area under the receiver operating characteristic (ROC) curve for each variable. Finally, we observed the time course of sBIS, sEMG, CVI, and the HR range before each somatic event and characterized the earliest time before the somatic event at which each variable was able to discriminate between the somatic events and a specified set of nonevents. RESULTS: The analysis included 33 somatic event segments and 829 nonevent segments from 105 surgical cases. The areas under the ROC curve (±SE) for sBIS, sEMG, and CVI were 0.83 ± 0.04, 0.92 ± 0.02, and 0.89 ± 0.03, respectively. The areas under the ROC curve for HR range and mean arterial blood pressure range were 0.77 ± 0.03 and 0.68 ± 0.05, respectively. CVI, sBIS, and sEMG all demonstrated higher average values before upcoming somatic events when compared with nonevents. HR range only showed a difference within a few seconds before the somatic event. CONCLUSION: sBIS, sEMG, and CVI, measures of electroencephalogram and EMG variability, increased when intraoperative somatic events occurred. sBIS, sEMG, and CVI discriminated between 10-minute segments that contained a somatic event and those segments that did not contain an event better than changes in HR and mean arterial blood pressure. Furthermore, CVI increases before somatic events began earlier than HR changes and may provide caregivers with an early warning of potentially inadequate antinociception.

Can remifentanil replace nitrous oxide during anesthesia for ambulatory orthopedic surgery with desflurane and fentanyl?

BACKGROUND: The administration of nitrous oxide (N2O) may be associated with side effects and toxicities. Remifentanil shares characteristics with N2O, including MAC-reducing and antinociceptive effects and a rapid decrease in clinical effect when discontinued. We compared the outcome after ambulatory orthopedic surgery with desflurane and fentanyl supplemented with clinically equivalent doses of either N2O or remifentanil. METHODS: Seventy patients undergoing ambulatory orthopedic surgery were studied. Thirty-five received 66% N2O and 35 received remifentanil 0.085 microg x kg(-1) x min(-1) in addition to desflurane, titrated to a bispectral index (BIS) value of 50, and a fentanyl infusion. The principle outcome measure was time to awakening to verbal stimulation. Secondary outcome measures included neuropsychological testing, time to orientation, hemodynamic values, pain and nausea visual analog scores, discharge times, and satisfaction scores. The average end-tidal desflurane concentration and fentanyl effect-site concentration were determined. RESULTS: The median time (interquartile range) to awakening to verbal stimulation, 3.0 min (3.0-5.0 min) in the remifentanil group and 4.6 min (3.0-8.1 min) in the N2O group was not significantly different. Median time to orientation was significantly faster in the remifentanil group: 6.0 min (5.0-8.5 min) compared with 8.0 min (5.0-12.8 min) for the N2O group. There was no difference between groups in desflurane or fentanyl administration, neuropsychological testing, or any other outcome measure. CONCLUSIONS: This study demonstrates that a remifentanil infusion of 0.085 microg x kg(-1) x min(-1) may be substituted for 66% N2O during desflurane/fentanyl anesthesia without any clinically significant change in outcome.

Bispectral index-derived facial electromyography-guided fentanyl titration in the opiate-exposed patient.

IMPLICATIONS: A 34-yr-old man, possibly opiate tolerant, underwent the second part of a scoliosis repair. We describe a narcotic titration protocol by using facial electromyography data derived from the bispectral index monitor that resulted in a good clinical outcome.