Recovery of consciousness and cognition after general anesthesia in humans.

Understanding how the brain recovers from unconsciousness can inform neurobiological theories of consciousness and guide clinical investigation. To address this question, we conducted a multicenter study of 60 healthy humans, half of whom received general anesthesia for 3 hr and half of whom served as awake controls. We administered a battery of neurocognitive tests and recorded electroencephalography to assess cortical dynamics. We hypothesized that recovery of consciousness and cognition is an extended process, with differential recovery of cognitive functions that would commence with return of responsiveness and end with return of executive function, mediated by prefrontal cortex. We found that, just prior to the recovery of consciousness, frontal-parietal dynamics returned to baseline. Consistent with our hypothesis, cognitive reconstitution after anesthesia evolved over time. Contrary to our hypothesis, executive function returned first. Early engagement of prefrontal cortex in recovery of consciousness and cognition is consistent with global neuronal workspace theory.

Anesthesia is a state of reversable, controlled unconsciousness. It has enabled countless medical procedures. But it also serves as a tool for scientists to study how the brain regains consciousness after disruptions such as sleep, coma or medical procedures requiring general anesthesia. It is still unclear how exactly the brain regains consciousness, and less so, why some patients do not recover normally after general anesthesia or fail to recover from brain injury. To find out more, Mashour et al. studied the patterns of reemerging consciousness and cognitive function in 30 healthy adults who underwent general anesthesia for three hours. While the volunteers were under anesthesia, their brain activity was measured with an EEG; and their sleep-wake activity was measured before and after the experiment. Each participant took part in a series of cognitive tests designed to measure the reaction speed, memory and other functions before receiving anesthesia, right after the return of consciousness, and then every 30 minutes thereafter. Thirty healthy volunteers who did not have anesthesia also completed the scans and tests as a comparison group. The experiments showed that certain normal EEG patterns resumed just before a person wakes up from anesthesia. The return of thinking abilities was an extended, multistep process, but volunteers recovered their cognitive abilities to nearly the same level as the volunteers within three hours of being deeply anesthetized. Mashour et al. also unexpectedly found that abstract problem-solving resumes early in the process, while other functions such as reaction time and attention took longer to recover. This makes sense from an evolutionary perspective. Sleep leaves individuals vulnerable. Quick evaluation and decision-making skills would be key to respond to a threat upon waking. The experiments confirm that the front of the brain, which handles thinking and decision-making, was especially active around the time of recovery. This suggests that therapies targeting this part of the brain may help people who experience loss of consciousness after a brain injury or have difficulties waking up after anesthesia. Moreover, disorders of cognition, such as delirium, in the days following surgery may be caused by factors other than the lingering effects of anesthetic drugs on the brain.

Risk of Persistent Opioid Use following Major Surgery in Matched Samples of Patients with and without Cancer.

BACKGROUND: The opioid crisis has reached epidemic proportions, yet risk of persistent opioid use following curative intent surgery for cancer and factors influencing this risk are not well understood. METHODS: We used electronic health record data from 3,901 adult patients who received a prescription for an opioid analgesic related to hysterectomy or large bowel surgery from January 1, 2013, through June 30, 2018. Patients with and without a cancer diagnosis were matched on the basis of demographic, clinical, and procedural variables and compared for persistent opioid use. RESULTS: Cancer diagnosis was associated with greater risk for persistent opioid use after hysterectomy [18.9% vs. 9.6%; adjusted OR (aOR), 2.26; 95% confidence interval (CI), 1.38-3.69; P = 0.001], but not after large bowel surgery (28.3% vs. 24.1%; aOR 1.25; 95% CI, 0.97-1.59; P = 0.09). In the cancer hysterectomy cohort, persistent opioid use was associated with cancer stage (increased rates among those with stage III cancer compared with stage I) and use of neoadjuvant or adjuvant chemotherapy; however, these factors were not associated with persistent opioid use in the large bowel cohort. CONCLUSIONS: Patients with cancer may have an increased risk of persistent opioid use following hysterectomy. IMPACT: Risks and benefits of opioid analgesia for surgical pain among patients with cancer undergoing hysterectomy should be carefully considered.

Management of the difficult airway in the COVID-19 pandemic: Illustrative complex head and neck cancer scenario.

BACKGROUND: This case highlights challenges in the assessment and management of the "difficult airway" patient in the SARS-CoV-2 (COVID-19) pandemic era. METHODS: A 60-year-old male with history of recent transoral robotic surgery resection, free flap reconstruction, and tracheostomy for p16+ squamous cell carcinoma presented with stridor and dyspnea 1 month after decannulation. Careful planning by a multidisciplinary team allowed for appropriate staffing and personal protective equipment, preparations for emergency airway management, evaluation via nasopharyngolaryngoscopy, and COVID testing. The patient was found to be COVID negative and underwent imaging which revealed new pulmonary nodules and a tracheal lesion. RESULTS: The patient was safely transorally intubated in the operating room. The tracheal lesion was removed endoscopically and tracheostomy was avoided. CONCLUSIONS: This case highlights the importance of careful and collaborative decision making for the management of head and neck cancer and other "difficult airway" patients during the COVID-19 epidemic.

The Year in Vascular Anesthesia: Selected Highlights From 2018.

This special article is the second in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia that is specifically dedicated to highlights in vascular anesthesiology published in 2018. This review begins with 2 updates in preoperative medicine in the vascular surgery population, including recent publications regarding the management of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers and antiplatelet medications in the perioperative period. The next section focuses on complications related to thoracic endovascular aortic surgery, particularly as technology advances allow for endovascular repair of more complex anatomy. The final section focuses on quality in vascular surgery and evaluates recent publications that examine the safety and feasibility of fast-track endovascular aortic surgery. Even though this is only a sampling of the literature published in 2018 relevant to the cardiovascular anesthesiologist, these themes represent some of the topics most clinically relevant to the perioperative period.

Sodium bicarbonate use and the risk of hypernatremia in thoracic aortic surgical patients with metabolic acidosis following deep hypothermic circulatory arrest.

OBJECTIVE: Metabolic acidosis after deep hypothermic circulatory arrest (DHCA) for thoracic aortic operations is commonly managed with sodium bicarbonate (NaHCO 3 ). The purpose of this study was to determine the relationships between total NaHCO 3 dose and the severity of metabolic acidosis, duration of mechanical ventilation, duration of vasoactive infusions, and Intensive Care Unit (ICU) or hospital length of stay (LOS). METHODS: In a single center, retrospective study, 87 consecutive elective thoracic aortic operations utilizing DHCA, were studied. Linear regression analysis was used to test for the relationships between the total NaHCO 3 dose administered through postoperative day 2, clinical variables, arterial blood gas values, and short-term clinical outcomes. RESULTS: Seventy-five patients (86%) received NaHCO 3 . Total NaHCO 3 dose averaged 136 ± 112 mEq (range: 0.0-535 mEq) per patient. Total NaHCO 3 dose correlated with minimum pH (r = 0.41, P < 0.0001), minimum serum bicarbonate (r = -0.40, P < 0.001), maximum serum lactate (r = 0.46, P = 0.007), duration of metabolic acidosis (r = 0.33, P = 0.002), and maximum serum sodium concentrations (r = 0.29, P = 0.007). Postoperative hypernatremia was present in 67% of patients and peaked at 12 h following DHCA. Eight percent of patients had a serum sodium ≥ 150 mEq/L. Total NaHCO 3 dose did not correlate with anion gap, serum chloride, not the duration of mechanical ventilator support, vasoactive infusions, ICU or hospital LOS. CONCLUSION: Routine administration of NaHCO 3 was common for the management of metabolic acidosis after DHCA. Total dose of NaHCO 3 was a function of the severity and duration of metabolic acidosis. NaHCO 3 administration contributed to postoperative hypernatremia that was often severe. The total NaHCO 3 dose administered was unrelated to short-term clinical outcomes.

Severity and Duration of Metabolic Acidosis After Deep Hypothermic Circulatory Arrest for Thoracic Aortic Surgery.

OBJECTIVE: To determine the severity, duration, and contributing factors for metabolic acidosis after deep hypothermic circulatory arrest (DHCA). DESIGN: Retrospective observational study. SETTING: University hospital. PATIENTS: Eighty-seven consecutive patients undergoing elective thoracic aortic surgery with DHCA. INTERVENTIONS: Regression analysis was used to test for relationships between the severity of metabolic acidosis and clinical and laboratory variables. MEASUREMENTS AND MAIN RESULTS: Minimum pH averaged 7.27±0.06, with 76 (87%) having a pH<7.35; 55 (63%), a pH<7.30; and 7 (8%), a pH<7.20. The mean duration of metabolic acidosis was 7.9±5.0 hours (range: 0.0 - 26.8), and time to minimum pH after DHCA was 4.3±2.0 hours (1.0 - 10.0 hours). Hyperchloremia contributed to metabolic acidosis in 89% of patients. The severity of metabolic acidosis correlated with maximum lactate (p<0.0001) and hospital length of stay (LOS) (r = 0.22, p<0.05), but not with DHCA time, DHCA temperature, duration of vasoactive infusions, or ICU LOS. Patient BMI was the sole preoperative predictor of the severity of postoperative metabolic acidosis. LIMITATIONS: This retrospective analysis involved short-term clinical outcomes related to pH severity and duration, which indirectly may have included the impact of sodium bicarbonate administration. CONCLUSIONS: Metabolic acidosis was common and severe after DHCA and was attributed to both lactic and hyperchloremic acidosis. DHCA duration and temperature had little impact on the severity of metabolic acidosis. The severity of metabolic acidosis was best predicted by the BMI and had minimal effects on short-term outcomes. Preventing hyperchloremic acidosis has the potential to decrease the severity of metabolic acidosis after DHCA.

Advancing extubation time for cardiac surgery patients using lean work design.

BACKGROUND: Early extubation in select cardiac surgery patients reduces tracheal intubation times, intensive care unit length of stay, and hospital length of stay. While there is good evidence in the literature to support early extubation, there is very little published research that describes how to study and redesign processes of care to increase early extubation rates. OBJECTIVE: To improve rates of early extubation by redesigning patient care processes using Lean principles to remove barriers to desired care and facilitate early extubation with guideline management. DESIGN: Retrospective data analysis. SETTING: Sixteen-bed intensive care unit in a mid-sized, academic community hospital. PATIENTS: Four hundred four patients undergoing coronary artery bypass graft surgery, aortic valve replacement, or mitral valve replacement/repair. INTERVENTION: The process of care for cardiac surgery patients, beginning with the immediate preoperative period and ending with extubation in the postoperative period, was analyzed using Lean methodologies. A value stream analysis was performed to identify waste in the process, and root causes for the largest sources of waste were identified. Hypothermia on admission to the intensive care unit, prolonged weaning using arterial blood gas results, hypertension management with pain medications and sedation medications, and delays in obtaining equipment were the primary reasons early extubation was delayed. Process redesign using Lean work design principles was implemented to eliminate these issues. MEASUREMENTS: The rate of patients being extubated in fewer than 6 hours and length of intubation. RESULTS: One hundred ninety-five pre-intervention subjects were compared with 171 post-intervention subjects. The pre- and post- groups did not differ in demographic predictors (Table 1). The intervention predicted extubation in<6 hours (pre-intervention 27% versus post-intervention 50%, p = 0.0001). Age, renal failure, and gender also predicted whether intubation occurred within 6 hours. The median length of intubation was lower post-intervention (pre-intervention 9.7 v post-intervention 6.1 hours, p = 0.0019) LIMITATIONS: The effect of this nonrandomized intervention could be due to other factors associated with a different care epoch. CONCLUSIONS: The closely planned, coordinated, and integrated care paradigm dramatically increased the likelihood of extubation within 6 hours of arrival in the SICU.

Steroids for surgery during cardiopulmonary bypass in adults: a meta-analysis.

STUDY OBJECTIVE: To evaluate the effect of steroid administration on myocardial infarction (MI), stroke, renal insufficiency, death, intensive care (ICU) length of stay (LOS) and hospital LOS of patients undergoing cardiopulmonary bypass (CPB). DESIGN: Meta-analysis of parallel randomized controlled trials. SETTING: University hospital. MEAUREMENTS: A search was conducted in PubMed, EMBASE, MEDLINE(R) and the Cochrane Central Register of Controlled Trials of studies on adults undergoing surgery with CPB who received steroid administration. Effect size (risk ratio or mean difference) for MI, stroke, renal insufficiency, death, ICU LOS, and hospital LOS were evaluated. MAIN RESULTS: 48 RCTs published between 1977 and 2012 were retained for analysis. Steroids had no effect on the MI risk ratio (RR) 0.91 (95% confidence interval [CI] 0.63, 1.32); death at 30 days RR 0.84 (0.59, 1.20); stroke RR 0.92 (0.60, 1.42) or renal insufficiency RR 0.83 (0.52, 1.32). Administration of steroids reduced ICU LOS (P = 0.00001; I(2) 87.5%) and hospital LOS (P = 0.03; I(2) 81.1%). Metaregressions showed that duration of steroid administration was correlated with the reduction in ICU LOS (P = 0.0004) and hospital LOS (P < 0.00001). CONCLUSIONS: Increasing the duration of steroid administration may reduce ICU and hospital LOS greater than increasing the dose.

Effects of adding statins before surgery on mortality and major morbidity: a meta-analysis.

OBJECTIVE: To re-evaluate the effects of adding a statin before surgery on mortality at 30 days and at 1 year and on major morbidity at 0-30 days. DESIGN: A meta-analysis of parallel, randomized, controlled trials published in English. SETTING: A university-based electronic search. PARTICIPANTS: Adult patients undergoing any type of procedure. INTERVENTION: Adding a statin before a procedure compared to a placebo or no intervention. MEASUREMENTS AND MAIN RESULTS: A search for all randomized controlled trials (RCT) was done in PubMed, Embase, Ovid MEDLINE and the Cochrane Central Register of Controlled Trials in November 2012. The quality of each study was assessed with the Cochrane Collaboration Tools. An I-square ≥ 25% was chosen as the cut-off point for heterogeneity exploration. The search produced 29 trials. Statins reduced the 0-30 days' risk of myocardial infarction: risk ratio (RR) 0.48 (95%CI 0.38, 0.61); I-square 13.2%; p<0.001; number needed-to-treat 17 (14, 24). There were no statistical differences at 0-30 days for stroke RR 0.70 (0.25, 1.95), acute renal insufficiency RR 0.54 (0.26, 1.12) or reoperation RR 1.10 (0.51, 2.38). There was a trend for a reduced mortality at 1 year RR 0.26 (0.06, 1.02); I-square 0%; p = 0.053. The hospital length of stay was slightly decreased with atorvastatin: standardized mean difference (SMD) -0.27 (-0.39, -0.14), p<0.001; fluvastatin SMD -0.95 (-1.56, -0.34), p = 0.002; and rosuvastatin SMD -0.69 (-0.98, -0.40), p<0.001 but not with simvastatin SMD -0.04 (-0.41, 0.48). CONCLUSIONS: Adding a statin before a high risk cardiac procedure reduces the 0-30 days' risk of myocardial infarction.

Intravenous GLP-1 (7-36) amide for prevention of hyperglycemia during cardiac surgery: a randomized, double-blind, placebo-controlled study.

OBJECTIVE: The authors sought to evaluate the efficacy of an intravenous glucagon-like peptide-1 (GLP-1) infusion, compared with placebo, to mitigate intraoperative hyperglycemia. DESIGN: Prospective, double-blinded, randomized, placebo-controlled. SETTING: University hospital. PARTICIPANTS: Diabetic (non-insulin dependent) and non-diabetic patients undergoing elective cardiac surgery with cardiopulmonary bypass. INTERVENTIONS: Patients were randomized in a 1:1 fashion to GLP-1 (7-36) amide infusion (1.5 pmol/kg/min) or placebo. Insulin was administered intraoperatively to both groups per a standardized protocol. MEASUREMENTS AND MAIN RESULTS: A total of 77 patients were included for analysis (GLP-1, n = 37; placebo, n = 40). Mean blood glucose during cardiopulmonary bypass was 127.5 mg/dL and 142.5 mg/dL (p = 0.002) in the GLP-1 and placebo groups, respectively. Mean blood glucose values during the entire intraoperative course were 12.2 mg/dL lower for subjects given GLP-1 (95% CI 2.3, 22, p = 0.015), independent of time. During the period of cardiopulmonary bypass, mean blood glucose values in subjects given GLP-1 were 14.1 mg/dL lower than those who received placebo (95% CI 3.5, 24.8, p = 0.009), independent of time. The incidence of hypoglycemia did not differ significantly between the 2 groups. CONCLUSIONS: Administration of intravenous GLP-1 (7-36) amide to patients undergoing cardiac surgery significantly reduced their plasma glucose levels intraoperatively and may represent a novel therapeutic strategy to prevent perioperative hyperglycemia.

Comparison between the analgesic efficacy of transversus abdominis plane (TAP) block and placebo in open retropubic radical prostatectomy: a prospective, randomized, double-blinded study.

STUDY OBJECTIVE: To compare the efficacy of ultrasound-guided tansversus abdominis plane (TAP) block with placebo for postoperative analgesia after retropubic radical prostatectomy (RRP). DESIGN: Prospective, randomized, double-blinded study. SETTING: Tertiary-care Veterans Affairs (VA) hospital. PATIENTS: ASA physical status 1, 2, and 3 patients scheduled for RRP. INTERVENTIONS: Patients were randomized to two groups: the TAP group and the control group. All patients underwent an ultrasound-guided TAP block procedure after induction of general anesthesia and received either local anesthetic (TAP group) or normal saline (control group). MEASUREMENTS: Opioid use and verbal analog pain scores at 1, 6, 12, and 24 hours after surgery were recorded, as was the frequency of side effects. Times to ambulation and first oral intake also were recorded. MAIN RESULTS: The TAP block group had lower pain scores and required less total opioid in the first 24 hours after surgery. Time to first oral intake and time to ambulation were similar between the two groups. CONCLUSION: The TAP block has early benefits in postoperative analgesia after RRP.

Validation study of Doppler-derived transmitral valve gradients compared to near simultaneously obtained directly measured catheter gradients immediately after mitral valve repair surgery.

OBJECTIVE: To evaluate the accuracy of Doppler-derived transmitral valve gradients immediately after mitral valve repair by comparing them with near simultaneously obtained direct catheter gradients. DESIGN: A prospective study. SETTING: A tertiary care medical center. PARTICIPANTS: Twenty elective adult surgical patients presenting for mitral valve repair surgery. METHODS: Mitral valve surgery proceeded in standard fashion except for the use of a smaller than usual left ventricular vent catheter (Medtronic DLP 10 French left heart vent catheter). After completion of the mitral valve repair and subsequent cardiac de-airing, the patient was weaned from cardiopulmonary bypass. Immediately after separation, the study period began. Near simultaneous transmitral Doppler gradients were obtained with directly measured catheter gradients via the vent catheter. RESULTS: While the mean peak gradient difference of 1.1 mmHg was small (p-value 0.18, 95% CI: -0.54 to 2.73 mmHg), the correlation between Doppler and catheter gradient measurements (Pearson correlation coefficient r = 0.54, p = 0.055) only approached statistical significance due to the large variance associated with the small sample size. In all patients with a peak gradient greater than 10 mmHg (4 of the 20 patients), overestimation of catheter gradients by Doppler occurred, with two showing a 62% to 73% discrepancy. In these two cases, there was also evidence for elevated left ventricular end-diastolic pressure (LVEDP) along with high transmitral blood flow velocities. CONCLUSION: Doppler-derived transmitral gradients provide a simple, safe, and reliable measure of the true physiologic transmitral valve gradient. At the same time, it is important to recognize that significant Doppler over-estimation of catheter gradients may occur in patients with elevated Doppler transmitral velocities. The causes of these overestimations are unknown. They may be related to technical recording errors. They may also be related to an inherent weakness in Doppler technology--its inability to account for any distal recovery of pressure, which in a select group of patients could be significant.

ß-blocking agents for surgery: influence on mortality and major outcomes. A meta-analysis.

OBJECTIVE: To re-evaluate the effects of perioperative beta-blockade on mortality and major outcomes after surgery. DESIGN: A meta-analysis of parallel randomized, controlled trials published in English. SETTING: A university-based electronic search. PARTICIPANTS: Patients undergoing surgery. INTERVENTIONS: Two interventions were evaluated: (1) Stopping or continuing a ß-blocker in patients on long-term ß-blocker therapy; and (2) Adding a ß-blocker for the perioperative period. MEASUREMENTS AND MAIN RESULTS: Stopping a ß-blocker before the surgery did not change the risk of myocardial infarction (3 studies including 97 patients): risk ratio (RR), 1.08 (95% confidence interval 0.30, 3.95); I(2), 0%. Adding a ß-blocker reduced the risk of death at 1 year: RR, 0.56 (0.31, 0.99); I(2), 0%; p = 0.046; number needed to treat 28 (19, 369) (4 studies with 781 patients). Adding a ß-blocker reduced the 0-to-30 day risk of myocardial infarction: RR, 0.65 (0.47, 0.88); I(2), 12.9%; p = 0.006 (15 studies with 12,224 patients), but increased the risk of a stroke: RR, 2.18 (1.40, 3.38); I(2), 0%; p = 0.001 (8 studies with 11,737 patients); number needed to harm 177 (512, 88). CONCLUSIONS: ß-blockers reduced the 1-year risk of death, and this effect seemed greater than the risk of inducing a stroke.

Implementation of an intraoperative glycemic control protocol for cardiac surgery in a high-acuity academic medical center: an observational study.

STUDY OBJECTIVE: To examine the effect on morbidity and mortality of an established intraoperative insulin protocol in cardiac surgical patients. DESIGN: Retrospective observational study. SETTING: Single-center, 782 bed, metropolitan academic hospital. PATIENTS: 1,616 adult patients undergoing cardiac surgical procedures with cardiopulmonary bypass (CPB). INTERVENTIONS: An intraoperative, intravenous (IV) insulin protocol designed to maintain blood glucose values less than 150 mg/dL was implemented. MEASUREMENTS: Blood glucose was evaluated on entry to the operating room, every 30 minutes during CPB, and at least once after discontinuation of CPB. Blood glucose values were followed postoperatively, as dictated by institutional policy. MAIN RESULTS: Intraoperative predictors of 30-day mortality using multivariate logistic regression included hyperglycemia on initiation of CPB (OR 1.0, P = 0.05). The strongest predictor of 30-day mortality was the development of postoperative renal failure requiring hemodialysis (OR 3.26, P = 0.001). CONCLUSIONS: Implementation of an intraoperative IV insulin protocol, while associated with improved glycemic control, was not associated with improved outcomes. While improved glycemic control on initiating CPB was associated with decreased 30-day mortality, the effect was small. Implementation of our insulin protocol was highly associated with decreased renal failure postoperatively. Further prospective studies are warranted to better establish causality.

Cardiac arrest associated with reperfusion of the liver during transplantation: incidence and proposal for a management algorithm.

Cardiac arrest associated with reperfusion of the liver allograft in a euvolemic patient is a rare but potentially devastating event. There are few case series describing experience with this complication and no published management protocols guiding treatment. This article is a retrospective case series of patients experiencing post-reperfusion intraoperative cardiac arrest between 1997 and 2011. Among 1581 liver transplants, 16 (1%) patients experienced post-reperfusion cardiac arrest. Among patients with intraoperative arrests, 14 (88%) patients required open cardiac massage. Seven (44%) were placed on cardiopulmonary bypass (CPB) when cardiac activity failed to adequately recover. Placement on CPB reversed cardiac pump failure and established a perfusing rhythm in six of seven (86%) recipients, leading to one of seven (14%) intraoperative mortality. Recovery of myocardial function was associated with low early survival with only 3/7 (43%) patients who underwent CPB surviving until discharge. Among all patients who survived the perioperative period, one-yr survival was 70% (N = 7), and five-yr survival was 50% (N = 5). Cardiac arrest during liver transplantation is associated with a poor prognosis during the perioperative period. In patients who do not recover cardiac activity after standard resuscitative measures, progression to physiologic support with systemic anticoagulation and CPB may allow correction of electrolyte derangements, maintenance of cerebral perfusion, and myocardial recovery.