The effects of dexmedetomidine on intraoperative neurophysiologic monitoring modalities during corrective scoliosis surgery in pediatric patients: A systematic review.

BACKGROUND: During scoliosis surgery, motor evoked potentials (MEP), and somatosensory evoked potentials (SSEP) have been reported to be affected by the use of higher doses of anesthetic agents. Dexmedetomidine, a sympatholytic agent, an alpha-2 receptor agonist, has been used as an adjunctive agent to lower anesthetic dose. However, there is conflicting evidence regarding the effects of dexmedetomidine on the intraoperative neurophysiological monitoring of MEP and SSEP during surgery, particularly among pediatric patients. OBJECTIVES: This systematic review aimed to determine whether, during spinal fusion surgery in pediatric patients with scoliosis, dexmedetomidine alters MEP amplitude or SSEP latency and amplitude and, if so, whether different doses of dexmedetomidine display different effects (PROSPERO registration number CRD42022300562). METHODS: We searched PubMed, Scopus, and Cochrane Library on January 1, 2022 and included randomized controlled trials, observational cohort and case-control studies and case series investigating dexmedetomidine in the population of interest and comparing against a standardized anesthesia regimen without dexmedetomidine or comparing multiple doses of dexmedetomidine. Animal and in vitro studies and conference abstracts were excluded. RESULTS: We found substantial heterogeneity in the risk of bias (per Cochrane-preferred tools) of the included articles (n = 5); results are summarized without meta-analysis. Articles with the lowest risk of bias indicated that dexmedetomidine was associated with MEP loss and that higher doses of dexmedetomidine increased risk. In contrast, articles reporting no association between dexmedetomidine and MEP loss suffered from higher risk of bias, including suspected or confirmed problems with confounding, outcome measurement, participant selection, results reporting, and lack of statistical transparency and power. CONCLUSION: Given the limitations of the studies available in the literature, it would be advisable to conduct rigorous randomized controlled trials with larger sample sizes to assess the effects of dexmedetomidine use of in scoliosis surgery in pediatric patients.

Multiorgan talks in the presence of brain injury.

PURPOSE OF REVIEW: The brain is the command center of the rest of the body organs. The normal multiorgan talks between the brain and the rest of the body organs are essential for the normal body homeostasis. In the presence of brain injury, the disturbed talks between the brain and the rest of body organs will result in several pathological conditions. The aim of this review is to present the most recent findings for the pathological conditions that would result from the impaired multiorgan talks in the presence of brain injury. RECENT FINDINGS: The brain injury such as in acute ischemic stroke, subarachnoid hemorrhage and traumatic brain injury will result in cascade of pathological talks between the brain and the rest of body organs. These pathological talks could result in pathological conditions such as cardiomyopathy, acute lung and kidney injuries, impaired liver functions, and impaired gut barrier permeability as well. SUMMARY: Better understanding of the pathological conditions that could result from the impaired multiorgan talks in the presence of brain injury will open the doors for precise targeted therapies in the future for myriad of pathological conditions.

Tidal Volume and Positive End-expiratory Pressure and Postoperative Hypoxemia during General Anesthesia: A Single-center Multiple Crossover Factorial Cluster Trial.

BACKGROUND: Intraoperative mechanical ventilation is a major component of general anesthesia. The extent to which various intraoperative tidal volumes and positive end-expiratory pressures (PEEP) effect on postoperative hypoxia and lung injury remains unclear. We hypothesized that adults having orthopedic surgery, ventilation using different tidal volumes and PEEP levels affect the oxygenation within first hour in the postoperative care unit. METHODS: We conducted a two-by-two factorial crossover cluster trial at the Cleveland Clinic Main Campus. We enrolled patients having orthopedic surgery with general anesthesia who were assigned to factorial clusters with tidal volumes of 6 or 10 ml/kg of predicted body weight and to PEEP of 5 or 8 cm H2O in 1-week clusters. The primary outcome was the effect of tidal volume or PEEP on time-weighted average peripheral oxygen saturation measured by pulse oximetry divided by the fraction of inspired oxygen (Spo2/Fio2 ratio) during the initial postoperative hour. RESULTS: We enrolled 2,860 patients who had general anesthesia for orthopedic surgery from September 2018 through October 2020. The interaction between tidal volume and PEEP was not significant (P = 0.565). The mean ± SD time-weighted average of Spo2/Fio2 ratio was 353 ± 47 and not different in patients assigned to high and low tidal volume (estimated effect, 3.5%; 97.5% CI, -0.4% to 7.3%; P = 0.042), for those assigned to high and low PEEP (estimated effect, -0.2%; 97.5% CI, -4.0% to 3.6%; P = 0.906). We did not find significant difference in ward Spo2/Fio2 ratio, pulmonary complications, and duration of hospitalization among patients assigned to various tidal volumes and PEEP levels. CONCLUSIONS: Among adults having major orthopedic surgery, postoperative oxygenation is similar, with tidal volumes between 6 and 10 ml/kg and PEEP between 5 and 8 cm H2O. Our results suggest that any combination of tidal volumes between 6 and 10 ml/kg and PEEP between 5 versus 8 ml cm H2O can be used safely for orthopedic surgery.

Co-Presentation of Posterior Reversible Encephalopathy Syndrome in a Patient with Post-Dural Puncture Headache.

INTRODUCTION: Post-dural puncture headache (PDPH) is a well-known complication of neuraxial anesthesia, but the occurrence of seizures and vision loss within a few days after dural puncture could be alarming. Posterior reversible encephalopathy syndrome (PRES) is associated with reversible edema and leukoencephalopathy in the posterior parieto-occipital cortex. We report the co-presentation of PRES and PDPH after labor epidural analgesia. CASE PRESENTATION: A 25-year-old multiparous African-American woman was admitted for evaluation of new-onset seizures and headache in the postpartum period. She had a recent history of multiple needle insertion attempts and inadvertent dural puncture during epidural analgesia for delivery. Soon after delivery, she was diagnosed with PDPH and was treated with an epidural blood patch, with no relief of symptoms. Six days later, she developed sudden-onset transient blindness, seizures, and altered sensorium, and magnetic resonance imaging of the brain revealed white matter changes suggestive of PRES. CONCLUSION: PRES is an uncommon complication of cerebrospinal fluid leak and intracranial hypotension. We report the occurrence of PRES in a patient with no known risk factors except a traumatic dural tap. Is it important to expand the differentials for headache after dural puncture to encompass PRES as a possibility, especially in patients with a delayed presentation of seizures and cortical blindness.

Oxygen Saturation and Postoperative Mortality in Patients With Acute Ischemic Stroke Treated by Endovascular Thrombectomy.

BACKGROUND: Monitored anesthesia care (MAC) and general anesthesia (GA) with endotracheal intubation are the 2 most used techniques for patients with acute ischemic stroke (AIS) undergoing endovascular thrombectomy. We aimed to test the hypothesis that increased arterial oxygen concentration during reperfusion period is a mechanism underlying the association between use of GA (versus MAC) and increased risk of in-hospital mortality. METHODS: In this retrospective cohort study, data were collected at the Cleveland Clinic between 2013 and 2018. To assess the potential mediation effect of time-weighted average oxygen saturation (Spo2) in first postoperative 48 hours between the association between GA versus MAC and in-hospital mortality, we assessed the association between anesthesia type and post-operative Spo2 tertiles (exposure-mediator relationship) through a cumulative logistic regression model and assessed the association between Spo2 and in-hospital mortality (mediator-outcome relationship) using logistic regression models. Confounding factors were adjusted for using propensity score methods. Both significant exposure-mediator and significant mediator-outcome relationships are needed to suggest potential mediation effect. RESULTS: Among 358 patients included in the study, 104 (29%) patients received GA and 254 (71%) received MAC, with respective hospital mortality rate of 19% and 5% (unadjusted P value <.001). GA patients were 1.6 (1.2, 2.1) (P < .001) times more likely to have a higher Spo2 tertile as compared to MAC patients. Patients with higher Spo2 tertile had 3.8 (2.1, 6.9) times higher odds of mortality than patients with middle Spo2 tertile, while patients in the lower Spo2 tertile did not have significant higher odds compared to the middle tertile odds ratio (OR) (1.8 [0.9, 3.4]; overall P < .001). The significant exposure-mediator and mediator-outcome relationships suggest that Spo2 may be a mediator of the relationship between anesthetic method and mortality. However, the estimated direct effect of GA versus MAC on mortality (ie, after adjusting for Spo2; OR [95% confidence interval {CI}] of 2.1 [0.9-4.9]) was close to the estimated association ignoring Spo2 (OR [95% CI] of 2.2 [1.0-5.1]), neither statistically significant, suggesting that Spo2 had at most a modest mediator role. CONCLUSIONS: GA was associated with a higher Spo2 compared to MAC among those treated by endovascular thrombectomy for AIS. Spo2 values that were higher than the middle tertile were associated with higher odds of mortality. However, GA was not significantly associated with higher odds of death. Spo2 at most constituted a modest mediator role in explaining the relationship between GA versus MAC and mortality.

Association between postoperative haemoglobin and myocardial injury after noncardiac surgery: a retrospective cohort analysis.

BACKGROUND: Myocardial injury after noncardiac surgery (MINS) is common, mostly silent, and a strong predictor of postoperative mortality. MINS appears to result from myocardial supply-demand mismatch. Recent data support restrictive perioperative transfusion strategies that can result in low postoperative haemoglobin concentrations. Whether low postoperative haemoglobin is associated with myocardial injury remains unknown. We therefore tested the hypothesis that anaemia is associated with an increased risk of myocardial injury in adults having noncardiac surgery. METHODS: We conducted a retrospective analysis of adults ≥45 yr old who had routine postoperative troponin T (TnT) monitoring after noncardiac surgery at the Cleverland Clinic (including those enrolled in the PeriOperative ISchemic Evaluation-2 Trial [POISE-2], the Safety of Addition of Nitrous Oxide to General Anaesthesia in At-risk Patients Having Major Non-cardiac Surgery [ENIGMA-II], Vascular Events In Noncardiac Surgery Patients Cohort Evaluation Study [VISION], and Anaesthetic Depth and Complications After Major Surgery [BALANCED] trial). Patients with baseline increase in TnT and non-ischaemic aetiologies for TnT increase were excluded. The association between postoperative haemoglobin concentration during the 3 initial postoperative days and the incidence of MINS (fourth-generation TnT ≥0.03 ng ml-1 judged as attributable to ischaemia) was assessed using a time-varying covariate Cox proportional hazards survival analysis. RESULTS: Among 6141 patients, 4480 were analysed. The incidence of MINS was 155/4480 (3.5%), ranging from 0/345 (0%) among patients whose lowest postoperative haemoglobin exceeded 13 g dl-1 to 52/611 (8.5%) in patients whose minimum postoperative haemoglobin was <8 g dl-1. The confounder-adjusted hazard ratio [95% confidence interval] for having MINS was 1.29 [1.16-1.42] for every 1 g dl-1 decrease in postoperative haemoglobin in a time-varying covariate analysis. Similar associations were identified in sensitivity analyses. CONCLUSION: Lower postoperative haemoglobin values are associated with MINS. Whether this association is modifiable by prevention or treatment of anaemia remains to be determined.

Sugammadex Versus Neostigmine for Reversal of Rocuronium Neuromuscular Block in Patients Having Catheter-Based Neurointerventional Procedures: A Randomized Trial.

BACKGROUND: Catheter-based endovascular neurointerventions require deep neuromuscular blocks during the procedure and rapid subsequent recovery of strength to facilitate neurological evaluation. We tested the primary hypothesis that sugammadex reverses deep neuromuscular blocks faster than neostigmine reverses moderate neuromuscular blocks. METHODS: Patients having catheter-based cerebral neurointerventional procedures were randomized to: (1) deep rocuronium neuromuscular block with posttetanic count 1 to 2 and 4-mg/kg sugammadex as the reversal agent or (2) moderate rocuronium neuromuscular block with train-of-four (TOF) count 1 during the procedure and neuromuscular reversal with 0.07-mg/kg neostigmine to a maximum of 5 mg. Recovery of diaphragmatic function was assessed by ultrasound at baseline before the procedure and 90 minutes thereafter. The primary outcome-time to reach a TOF ratio ≥0.9 after administration of the designated reversal agent-was analyzed with a log-rank test. Secondary outcomes included time to successful tracheal extubation and the difference between postoperative and preoperative diaphragmatic contraction speed and distance. RESULTS: Thirty-five patients were randomized to sugammadex and 33 to neostigmine. Baseline characteristics and surgical factors were well balanced. The median time to reach TOF ratio ≥0.9 was 3 minutes (95% confidence interval [CI], 2-3 minutes) in patients given sugammadex versus 8 minutes (95% CI, 6-10 minutes) in patients given neostigmine. Sugammadex was significantly faster by a median of 5 minutes (95% CI, 3-6 minutes; P < .001). However, times to tracheal extubation and diaphragmatic function at 90 minutes did not differ significantly. CONCLUSIONS: Sugammadex reversed deep rocuronium neuromuscular blocks considerably faster than neostigmine reversed moderate neuromuscular blocks. However, times to extubation did not differ significantly, apparently because extubation was largely determined by the time required for awaking from general anesthesia and because clinicians were willing to extubate before full neuromuscular recovery. Sugammadex may nonetheless be preferable to procedures that require a deep neuromuscular block and rapid recovery.

Deep Hypothermic Circulatory Arrest in the Pediatric Population Undergoing Cardiac Surgery With Electroencephalography Monitoring: A Systematic Review and Meta-Analysis.

OBJECTIVE: Cardiac surgery for repair of congenital heart defects poses unique hazards to the developing brain. Deep hypothermic circulatory arrest (DHCA) is a simple and effective method for facilitating a bloodless surgical field during congenital heart defect repair. There are, however, some concerns that prolonged DHCA increases the risk of nervous system injury. The electroencephalogram (EEG) is used in adult and, to a lesser extent, pediatric cardiac procedures as a neuromonitoring method. The present study was performed to assess outcomes following DHCA with EEG monitoring in the pediatric population. DESIGN: In this systematic review and meta-analysis, the PubMed, Cochrane Central Register of Controlled Trials, Scopus, Institute of Science Index, and Embase databases were searched from inception for relevant articles. A fixed- or random-effects model, as appropriate, was used. SETTING: Surgical setting. PARTICIPANTS: Pediatric population (≤18 y old). INTERVENTIONS: DHCA (18°C) with EEG monitoring. MEASUREMENTS AND MAIN RESULTS: Nineteen articles with 1,267 pediatric patients ≤18 years were included. The event rate of clinical and EEG seizures among patients who underwent DHCA was 12.9% and 14.9%, respectively. Mortality was found to have a 6.3% prevalence. A longer duration of DHCA was associated with a higher risk of EEG seizure and neurologic abnormalities. In addition, seizures were associated with increased neurologic abnormalities and neurodevelopmental delay. CONCLUSIONS: EEG and neurologic abnormalities were common after DHCA. A longer duration of DHCA was found to lead to more EEG seizure and neurologic abnormalities. Moreover, EEG seizures were more common than clinical seizures. Seizures were found to be associated with increased neurologic abnormalities and neurodevelopmental delay.

Metal-Bound Methisazone; Novel Drugs Targeting Prophylaxis and Treatment of SARS-CoV-2, a Molecular Docking Study.

SARS-CoV-2 currently lacks effective first-line drug treatment. We present promising data from in silico docking studies of new Methisazone compounds (modified with calcium, Ca; iron, Fe; magnesium, Mg; manganese, Mn; or zinc, Zn) designed to bind more strongly to key proteins involved in replication of SARS-CoV-2. In this in silico molecular docking study, we investigated the inhibiting role of Methisazone and the modified drugs against SARS-CoV-2 proteins: ribonucleic acid (RNA)-dependent RNA polymerase (RdRp), spike protein, papain-like protease (PlPr), and main protease (MPro). We found that the highest binding interactions were found with the spike protein (6VYB), with the highest overall binding being observed with Mn-bound Methisazone at -8.3 kcal/mol, followed by Zn and Ca at -8.0 kcal/mol, and Fe and Mg at -7.9 kcal/mol. We also found that the metal-modified Methisazone had higher affinity for PlPr and MPro. In addition, we identified multiple binding pockets that could be singly or multiply occupied on all proteins tested. The best binding energy was with Mn-Methisazone versus spike protein, and the largest cumulative increases in binding energies were found with PlPr. We suggest that further studies are warranted to identify whether these compounds may be effective for treatment and/or prophylaxis.

Timing of Tracheostomy in Pediatric Patients: A Systematic Review and Meta-Analysis.

OBJECTIVES: Tracheostomy is a very common clinical intervention in critically ill adult patients. The indications for tracheostomy procedures in pediatric patients with complex conditions have increased dramatically in recent years, but there are currently no guidelines on the optimal timing of tracheostomy in pediatric patients undergoing prolonged ventilation. DATA SOURCES: We performed a systematic search of the existing literature in MEDLINE via PubMed and Embase databases and the Cochrane Library to identify clinical trials, observational studies, and cohort studies that compare early and late tracheostomy in children. The date of the last search was August 27, 2018. Included articles were subjected to manual searching. STUDY SELECTION: Studies in mechanically ventilated children that compared early with late tracheostomy were included. DATA EXTRACTION: Data were extracted into a spreadsheet and copied into Review Manager 5.3 (The Cochrane Collaboration, Copenhagen, Denmark). DATA SYNTHESIS: Data were meta-analyzed using an inverse variance, random effects model. Continuous outcomes were calculated as mean differences with 95% CIs, and dichotomous outcomes were calculated as Mantel-Haenszel risk ratios with 95% CIs. We included eight studies (10 study arms). These studies were all retrospective cohort studies. Early tracheostomy was associated with significant reductions in mortality, days on mechanical ventilation, and length of intensive care and total hospital stay, although the lack of randomized, controlled trials limits the validity of these findings. Although variance was imputed for some studies, these conclusions did not change after removing these studies from the analysis. CONCLUSIONS: In children on mechanical ventilation, early tracheostomy may improve important medical outcomes. However, our data demonstrate the urgent need for high-quality, randomized controlled trials in the pediatric population.

Association between Use of Angiotensin-converting Enzyme Inhibitors or Angiotensin Receptor Blockers and Postoperative Delirium.

BACKGROUND: Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers improve cognitive function. The authors therefore tested the primary hypothesis that preoperative use of angiotensin inhibitors is associated with less delirium in critical care patients. Post hoc, the association between postoperative use of angiotensin system inhibitors and delirium was assessed. METHODS: The authors conducted a single-site cohort study of adults admitted to Cleveland Clinic critical care units after noncardiac procedures between 2013 and 2018 who had at least one Confusion Assessment Method delirium assessment. Patients with preexisting dementia, Alzheimer's disease or other cognitive decline, and patients who had neurosurgical procedures were excluded. For the primary analysis, the confounder-adjusted association between preoperative angiotensin inhibitor use and the incidence of postoperative delirium was assessed. Post hoc, the confounder-adjusted association between postoperative angiotensin system inhibitor use and the incidence of delirium was assessed. RESULTS: The incidence of delirium was 39% (551 of 1,396) among patients who were treated preoperatively with angiotensin system inhibitors and 39% (1,344 of 3,468) in patients who were not. The adjusted odds ratio of experiencing delirium during critical care was 0.98 (95% CI, 0.86 to 1.10; P = 0.700) for preoperative use of angiotensin system inhibitors versus control. Delirium was observed in 23% (100 of 440) of patients who used angiotensin system inhibitors postoperatively before intensive care discharge, and in 41% (1,795 of 4,424) of patients who did not (unadjusted P < 0.001). The confounder-adjusted odds ratio for experiencing delirium in patients who used angiotensin system inhibitors postoperatively was 0.55 (95% CI, 0.43 to 0.72; P < 0.001). CONCLUSIONS: Preoperative use of angiotensin system inhibitors is not associated with reduced postoperative delirium. In contrast, treatment during intensive care was associated with lower odds of delirium. Randomized trials of postoperative angiotensin-converting enzymes inhibitors and angiotensin receptor blockers seem justified.

Association Between Perioperative Hypotension and Delirium in Postoperative Critically Ill Patients: A Retrospective Cohort Analysis.

BACKGROUND: Postoperative delirium is common in critically ill patients, with a reported incidence of 11%-43%, and is associated with significant morbidity and cost. Perioperative hypotension and consequent brain hypoperfusion may contribute. We, therefore, tested the hypotheses that intraoperative and postoperative hypotension are associated with critical care delirium. METHODS: We included 1083 postoperative patients who were admitted directly from an operating room to the surgical intensive care unit. Delirium was assessed with the Confusion Assessment Method for Intensive Care Unit patients at 12-hour intervals. We used a confounder-adjusted Cox proportional hazard survival model to assess the association between the amount of intraoperative hypotension, which was measured as the time-weighted average of mean arterial pressure <65 mm Hg, and delirium while in critical care. Thereafter, we used a Cox model with the lowest mean arterial pressure on each intensive care day as a time-varying covariate to assess the relationship between critical care hypotension and delirium, adjusted for confounders and amount of intraoperative hypotension. RESULTS: Three hundred seventy-seven (35%) patients had delirium within the first 5 postoperative days in the surgical intensive care unit. Intraoperative hypotension was moderately associated with higher odds of postoperative delirium. The adjusted hazard ratio associated with 1 mm Hg increase in time-weighted average of mean arterial pressure <65 mm Hg was 1.11 (95% confidence interval [CI], 1.03-1.20; P = .008). Postoperatively, a 10 mm Hg reduction in the lowest mean pressure on each day in the critical care unit was significantly associated with a higher hazard of delirium, with an adjusted hazard ratio 1.12 (95% CI, 1.04-1.20; P = .003). CONCLUSIONS: Both intraoperative and postoperative hypotension are associated with delirium in postoperative critical care patients. The extent to which these relationships are causal remains unknown, but to the extent that they are, hypotension prevention may help reduce delirium and should be studied in prospective clinical trials.

Antistasis Retrograde Flow Vascular Catheter: A Novel Solution to Thrombogenicity: A Computational Fluid Dynamics Study.

BACKGROUND: Catheter-related thrombosis (CRT) is a serious complication of vascular catheters. Retrograde catheter insertion has been shown to decrease pericatheter hemostasis and thrombosis, but it is technically challenging. The current in silico trial is an analytical approach to evaluating different approaches to designing retrograde flow into a vascular catheter. METHODS: The novel catheter design aims to provide antistasis retrograde flow (ASRF) of fluid through multiple backward-directed side openings, with a self-closing terminal opening to facilitate standard insertion. Four different models of the catheter were evaluated by computational fluid dynamic studies, with retrograde-angled openings of 15°, 30°, 45°, and 60° to the long axis of the catheter. RESULTS: ASRF successfully reduced the areas of fluid stagnation in models with 15° and 30° openings. Models with 45° and 60° did not significantly reduce stagnation. ASRF is reversed by the main bloodstream after a few millimeters. The novel catheter design achieved a slightly higher saline flow rate compared with the standard catheter (89.75, 91.72, 94.13, and 94.26 mL/min for 15°, 30°, 45°, and 60° designs, respectively, versus 86.93 mL/min for the standard catheter). CONCLUSIONS: The novel ASRF vascular catheter reduces pericatheter fluid stasis and has the potential to reduce CRT. Further in vitro and in vivo trials are warranted to validate these findings and evaluate clinical efficacy.

Triple-low Alerts Do Not Reduce Mortality: A Real-time Randomized Trial.

BACKGROUND: Triple-low events (mean arterial pressure less than 75 mmHg, Bispectral Index less than 45, and minimum alveolar fraction less than 0.8) are associated with mortality but may not be causal. This study tested the hypothesis that providing triple-low alerts to clinicians reduces 90-day mortality. METHODS: Adults having noncardiac surgery with volatile anesthesia and Bispectral Index monitoring were electronically screened for triple-low events. Patients having triple-low events were randomized in real time, with clinicians either receiving an alert, "consider hemodynamic support," or not. Patients were blinded to treatment. Helpful responses to triple-low events were defined by administration of a vasopressor within 5 min or a 20% reduction in end-tidal volatile anesthetic concentration within 15 min. RESULTS: Of the qualifying patients, 7,569 of 36,670 (20%) had triple-low events and were randomized. All 7,569 were included in the primary analysis. Ninety-day mortality was 8.3% in the alert group and 7.3% in the nonalert group. The hazard ratio (95% CI) for alert versus nonalert was 1.14 (0.96, 1.35); P = 0.12, crossing a prespecified futility boundary. Clinical responses were helpful in about half the patients in each group, with 51% of alert patients and 47% of nonalert patients receiving vasopressors or having anesthetics lowered after start of triple low (P < 0.001). There was no relationship between the response to triple-low events and adjusted 90-day mortality. CONCLUSIONS: Real-time alerts to triple-low events did not lead to a reduction in 90-day mortality, and there were fewer responses to alerts than expected. However, similar mortality with and without responses suggests that there is no strong relationship between responses to triple-low events and mortality.

Vasopressor Infusion During Prone Spine Surgery and Acute Renal Injury: A Retrospective Cohort Analysis.

BACKGROUND: Hypotension is associated with acute kidney injury, but vasopressors used to treat hypotension may also compromise renal function. We therefore tested the hypothesis that vasopressor infusion during complex spine surgery is not associated with impaired renal function. METHODS: In this 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. RESULTS: 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. CONCLUSIONS: 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.

The relative effects of dexmedetomidine and propofol on cerebral blood flow velocity and regional brain oxygenation: A randomised noninferiority trial.

BACKGROUND: Dexmedetomidine constricts cerebral blood vessels without a concomitant reduction in cerebral metabolic oxygen consumption. Its safety as a sedative in patients with neurological diseases thus remains uncertain. OBJECTIVE: Our primary objective was to test the hypothesis that dexmedetomidine is noninferior to propofol as regards cerebral blood flow (CBF) velocity and brain oxygenation. DESIGN: Unblinded randomised trial. SETTING: Cleveland Clinic Hospital, Cleveland, from November 2010 to July 2013. PATIENTS: Forty-four patients scheduled for insertion of a deep-brain stimulating electrodes. INTERVENTIONS: Patients were randomised to receive either dexmedetomidine or propofol sedation during deep-brain stimulating electrode insertion. MAIN OUTCOME MEASURES: Intraoperative CBF velocity was measured with transcranial Doppler, and brain oxygenation was assessed with near-infrared spectroscopy. Noninferiority of dexmedetomidine to propofol was defined as a less than 20% difference in means. RESULTS: Twenty-three patients were given dexmedetomidine and 21 propofol. Baseline characteristics and operative management were similar in each group. Dexmedetomidine was noninferior to propofol on both CBF and brain oxygenation, confirming our primary hypothesis. For cerebral flood flow, the estimated ratio of means (dexmedetomidine/propofol) was 0.94 [90% CI: 0.84 to 1.05], P = 0.011 for noninferiority. For brain oxygenation, the estimated ratio of means was 0.99 [90% CI: 0.96 to 1.02], P < 0.001 for noninferiority. Superiority was not found for either primary outcome. Dexmedetomidine provided deeper sedation than propofol, with a difference of medians of 1 [90% CI: 0 to 2], P < 0.001 on the Observer's Assessment of Alertness/Sedation scale. No significant differences were observed in pulsatility index, cerebral perfusion pressure, number of hypertensive or apnoeic episodes. CONCLUSION: Regional brain oxygenation and CBF velocity are comparably preserved during dexmedetomidine and propofol sedation. Thus, the use of dexmedetomidine in patients with movement disorders appears reasonable. TRIAL REGISTRATION: The trial was registered at ClinicalTrials.gov (NCT 01200433).

Novel needle guide reduces time to perform ultrasound-guided femoral nerve catheter placement: A randomised controlled trial.

BACKGROUND: Ultrasound-guided nerve blocks have become the standard when performing regional nerve blocks in anaesthesia. Infiniti Plus (CIVCO Medical Solutions, Kalona, Iowa, USA) is a needle guide that has been recently developed to help clinicians in performing ultrasound-guided nerve blocks. OBJECTIVES: We tested the hypothesis that femoral nerve catheter placement carried out with the Infiniti Plus needle guide will be quicker to perform than without the Infiniti Plus. Secondary aims were to assess whether the Infiniti Plus needle guide decreased the number of block attempts and also whether it improved needle visibility. DESIGN: A randomised, controlled trial. SETTING: Cleveland Clinic, Cleveland, Ohio, USA. PATIENTS: We enrolled adult patients having elective total knee arthroplasty with a femoral nerve block and femoral nerve catheter. Patients, who were pregnant or those who had preexisting neuropathy involving the surgical limb, coagulopathy, infection at the block site or allergy to local anaesthetics were excluded. INTERVENTIONS: Patients were randomised into two groups to receive the ultrasound-guided femoral nerve catheter placement with or without the Infiniti Plus needle guide. MAIN OUTCOME MEASURES: The time taken to place the femoral nerve catheter, the number of attempts, the success rate and needle visibility were recorded. We used an overall α of 0.05 for both the primary and secondary analyses; the secondary analyses were Bonferroni corrected to control for multiple comparisons. RESULT: The median (interquartile range Q1 to Q3) time to perform the femoral nerve catheter placement was 118 (100 to 150) s with Infiniti Plus and 177 (130 to 236) s without Infiniti Plus. Infiniti Plus significantly reduced the time spent performing femoral nerve catheterisation, with estimated ratio of means [(95% confidence interval), P value] of 0.67 [(0.60 to 0.75), P < 0.001] with Infiniti Plus compared with no Infiniti Plus. However, Infiniti Plus had no effect on the odds of a successful femoral nerve catheter placement, number of attempts or percentage of perfect needle visibility. CONCLUSION: We found that the use of Infiniti Plus decreased the median time to successfully place a femoral nerve catheter by 33% compared with not using Infiniti Plus. This difference may be more apparent to clinicians undertaking this procedure less often or by those in training as our team was very experienced, had been trained in the technique and was working in a hospital with a large caseload. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT02080481.

The Association Between Mild Intraoperative Hypotension and Stroke in General Surgery Patients.

BACKGROUND: Intraoperative hypotension may contribute to perioperative strokes. We therefore tested the hypothesis that intraoperative hypotension is associated with perioperative stroke. METHODS: After institutional review board approval for this case-control study, we identified patients who had nonneurological, noncardiac, and noncarotid surgery under general anesthesia at the Cleveland Clinic between 2005 and 2011 and experienced a postoperative stroke. Control patients not experiencing postoperative stroke were matched in a 4-to-1 ratio using propensity scores and restriction to the same procedure type as stroke patients. The association between intraoperative hypotension, measured as time-integrated area under a mean arterial pressure (MAP) of 70 mm Hg, and postoperative stroke was assessed using zero-inflated negative binomial regression. RESULTS: Among 106 337 patients meeting inclusion criteria, we identified 120 who had confirmed postoperative stroke events based on manual chart review. Four-to-one propensity matching yielded a final matched sample of 104 stroke cases and 398 controls. There was no association between stroke and intraoperative hypotension. Stroke patients were not more likely than controls to have been hypotensive (odds ratio, 0.49 [0.18-1.38]), and among patients with intraoperative hypotension, stroke patients did not experience a greater degree of hypotension than controls (ratio of geometric means, 1.07 [0.76-1.53]). CONCLUSIONS: In our propensity score-matched case-control study, we did not find an association between intraoperative hypotension, defined as MAP < 70 mm Hg, and postoperative stroke.

Development of technologies for placement of perineural catheters.

Continuous peripheral nerve block (CPNB) success is largely dependent on placement of the catheter close enough to the nerve to allow effective and sustained analgesia following painful surgeries with a minimum volume of local anesthetic. One of the most common problems associated with CPNB involves accurate placement of the catheter tip, migration, and dislodgement of the catheter. This is of increasing importance now that catheters are left in place for prolonged periods of time to provide postoperative analgesia, and patients with peripheral nerve catheters are being discharged home with ambulatory pumps. In response to the challenges of providing safe, effective, and consistently reliable analgesia, research and development in this field is expanding rapidly. This review article presents results from recent publications addressing the subject of peripheral nerve catheter localization.