Preoperative cerebral oxygenation in high-risk noncardiac surgical patients: an observational study on postoperative mortality and complications

Near Infrared Spectroscopy (NIRS) has become widely accepted to evaluate regional cerebral oxygen saturation (rScO2), potentially acting as a surrogate parameter of reduced cerebral oxygen delivery or increased consumption. Low preoperative rScO2 is associated with increased postoperative complications after cardiac surgery. However, its universal potential in pre-anesthesia risk assessment remains unclear. Therefore, we investigated whether low preoperative rScO2 is indicative of postoperative complications and associated with poor outcomes in noncardiac surgical patients. We prospectively enrolled 130 patients undergoing high-risk noncardiac surgery. During pre-anesthesia evaluation, baseline rScO2 was recorded with and without oxygen supplementation. The primary endpoint was 30-day mortality, while secondary endpoints were postoperative myocardial injury, respiratory complications, and renal failure. We further evaluated the impact of body position and preoperative hemoglobin (Hb) concentration on rScO2. Of the initially enrolled 130 patients, 126 remained for final analysis. Six (4.76%) patients died within 30 postoperative days. 95 (75.4%) patients were admitted to the ICU. 32 (25.4%) patients suffered from major postoperative complications. There was no significant association between rScO2 and 30-day mortality or secondary endpoints. Oxygen supplementation induced a significant increase of rScO2. Furthermore, Hb concentration correlated with rScO2 values and body position affected rScO2. No significant association between rScO2 values and NYHA, LVEF, or MET classes were observed. Preoperative rScO2 is not associated with postoperative complications in patients undergoing high-risk noncardiac surgery. We speculate that the discriminatory power of NIRS is insufficient due to individual variability of rScO2 values and confounding factors.

External Validation of the Revised Cardiac Risk Index and the Geriatric-Sensitive Perioperative Cardiac Risk Index in Oldest Old Patients Following Surgery Under Spinal Anaesthesia; a Retrospective Cross-Sectional Cohort Study

Background

The Revised Cardiac Risk Index (RCRI) and the Geriatric Sensitive Cardiac Risk Index (GSCRI) estimate the risk of postoperative major adverse cardiac events (MACE) regardless of the type of anesthesia and without specifying the oldest old patients. Since spinal anesthesia (SA) is a preferred technique in geriatrics, we aimed to test the external validity of these indices in patients ≥ 80 years old who underwent surgery under SA and tried to identify other potential risk factors for postoperative MACE.

Methods

The performance of both indices to estimate postoperative in-hospital MACE risk was tested through discrimination, calibration, and clinical utility. We also investigated the correlation between both indices and postoperative ICU admission and length of hospital stay (LOS).

Results

The MACE incidence was 7.5%. Both indices had limited discriminative (AUC for RCRI and GSCRI were 0.69 and 0.68, respectively) and predictive abilities. The regression analysis showed that patients with atrial fibrillation (AF) were 3.77 and those with trauma surgery were 2.03 times more likely to exhibit MACE, and the odds of MACE increased by 9% for each additional year above 80. Introducing these factors into both indices (multivariable models) increased the discriminative ability (AUC reached 0.798 and 0.777 for RCRI and GSCRI, respectively). Bootstrap analysis showed that the predictive ability of the multivariate GSCRI but not the multivariate RCRI improved. Decision curve analysis (DCA) showed that multivariate GSCRI had superior clinical utility when compared with multivariate RCRI. Both indices correlated poorly with postoperative ICU admission and LOS.

Conclusion

Both indices had limited predictive and discriminative ability to estimate postoperative in-hospital MACE risk and correlated poorly with postoperative ICU admission and LOS, following surgery under SA in the oldest-old patients. Updated versions by introducing age, AF, and trauma surgery improved the GSCRI performance but not the RCRI.

Key characteristics impacting survival of COVID-19 extracorporeal membrane oxygenation

Background

Severe COVID-19 induced acute respiratory distress syndrome (ARDS) often requires extracorporeal membrane oxygenation (ECMO). Recent German health insurance data revealed low ICU survival rates. Patient characteristics and experience of the ECMO center may determine intensive care unit (ICU) survival. The current study aimed to identify factors affecting ICU survival of COVID-19 ECMO patients.

Methods

673 COVID-19 ARDS ECMO patients treated in 26 centers between January 1st 2020 and March 22nd 2021 were included. Data on clinical characteristics, adjunct therapies, complications, and outcome were documented. Block wise logistic regression analysis was applied to identify variables associated with ICU-survival.

Results

Most patients were between 50 and 70 years of age. PaO₂/FiO₂ ratio prior to ECMO was 72 mmHg (IQR: 58–99). ICU survival was 31.4%. Survival was significantly lower during the 2nd wave of the COVID-19 pandemic. A subgroup of 284 (42%) patients fulfilling modified EOLIA criteria had a higher survival (38%) (p = 0.0014, OR 0.64 (CI 0.41–0.99)). Survival differed between low, intermediate, and high-volume centers with 20%, 30%, and 38%, respectively (p = 0.0024). Treatment in high volume centers resulted in an odds ratio of 0.55 (CI 0.28–1.02) compared to low volume centers. Additional factors associated with survival were younger age, shorter time between intubation and ECMO initiation, BMI > 35 (compared to < 25), absence of renal replacement therapy or major bleeding/thromboembolic events.

Conclusions

Structural and patient-related factors, including age, comorbidities and ECMO case volume, determined the survival of COVID-19 ECMO. These factors combined with a more liberal ECMO indication during the 2nd wave may explain the reasonably overall low survival rate. Careful selection of patients and treatment in high volume ECMO centers was associated with higher odds of ICU survival.

Trial registration

Registered in the German Clinical Trials Register (study ID: DRKS00022964, retrospectively registered, September 7th 2020, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00022964.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04053-6.

Effect of Intraoperative Handovers of Anesthesia Care on Mortality, Readmission, or Postoperative Complications Among Adults: The HandiCAP Randomized Clinical Trial

IMPORTANCE

Intraoperative handovers of anesthesia care are common. Handovers might improve care by reducing physician fatigue, but there is also an inherent risk of losing critical information. Large observational analyses report associations between handover of anesthesia care and adverse events, including higher mortality.

OBJECTIVE

To determine the effect of handovers of anesthesia care on postoperative morbidity and mortality.

DESIGN, SETTING, AND PARTICIPANTS

This was a parallel-group, randomized clinical trial conducted in 12 German centers with patients enrolled between June 2019 and June 2021 (final follow-up, July 31, 2021). Eligible participants had an American Society of Anesthesiologists physical status 3 or 4 and were scheduled for major inpatient surgery expected to last at least 2 hours.

INTERVENTIONS

A total of 1817 participants were randomized to receive either a complete handover to receive anesthesia care by another clinician (n = 908) or no handover of anesthesia care (n = 909). None of the participating institutions used a standardized handover protocol.

MAIN OUTCOMES AND MEASURES

The primary outcome was a 30-day composite of all-cause mortality, hospital readmission, or serious postoperative complications. There were 19 secondary outcomes, including the components of the primary composite, along with intensive care unit and hospital lengths of stay.

RESULTS

Among 1817 randomized patients, 1772 (98%; mean age, 66 [SD, 12] years; 997 men [56%]; and 1717 [97%] with an American Society of Anesthesiologists physical status of 3) completed the trial. The median total duration of anesthesia was 267 minutes (IQR, 206-351 minutes), and the median time from start of anesthesia to first handover was 144 minutes in the handover group (IQR, 105-213 minutes). The composite primary outcome occurred in 268 of 891 patients (30%) in the handover group and in 284 of 881 (33%) in the no handover group (absolute risk difference [RD], -2.5%; 95% CI, -6.8% to 1.9%; odds ratio [OR], 0.89; 95% CI, 0.72 to 1.10; P = .27). Nineteen of 889 patients (2.1%) in the handover group and 30 of 873 (3.4%) in the no handover group experienced all-cause 30-day mortality (absolute RD, -1.3%; 95% CI, -2.8% to 0.2%; OR, 0.61; 95% CI, 0.34 to 1.10; P = .11); 115 of 888 (13%) vs 136 of 872 (16%) were readmitted to the hospital (absolute RD, -2.7%; 95% CI, -5.9% to 0.6%; OR, 0.80; 95% CI, 0.61 to 1.05; P = .12); and 195 of 890 (22%) vs 189 of 874 (22%) experienced serious postoperative complications (absolute RD, 0.3%; 95% CI, -3.6% to 4.1%; odds ratio, 1.02; 95% CI, 0.81 to 1.28; P = .91). None of the 19 prespecified secondary end points differed significantly.

CONCLUSIONS AND RELEVANCE

Among adults undergoing extended surgical procedures, there was no significant difference between the patients randomized to receive handover of anesthesia care from one clinician to another, compared with the no handover group, in the composite primary outcome of mortality, readmission, or serious postoperative complications within 30 days.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04016454.

[Tracheal rupture following endotracheal intubation for an emergency cesarean]

This is a case report of a 45-year-old patient, 39 weeks of gestation, who was intubated via rapid sequence induction (RSI) for an emergency cesarean. The indication for emergency cesarean was a pathological cardiotocography during the ejection phase following labor induction.Despite the primary use of a video laryngoscope, there was difficulty aligning the laryngeal axis. Therefore, an internal stylet was used to heavily angulate the endotracheal tube (ETT) to a hockey stick shape to enter the larynx.Postoperative dyspnea and extensive facial swelling were initially diagnosed as an allergic reaction. Only 22 h later the diagnosis of tracheal rupture was confirmed following computer tomography.We hypothesized that the mechanism of injury was due to excessive pressure transmitted to the tip of the ETT. This probably occurred due to a leverage effect caused by the withdrawal of the heavily bent stylet from the ETT, forcing an intratracheal cranial movement of the ETT.By conducting an experiment on a pig's trachea, we were able to visualize this mechanism of injury. In addition, we were able to demonstrate that bending the stylet to a similar angle as the laryngoscope blade led to minimal movement of the tip of the ETT.Therefore, when using a stylet during intubation, we recommend bending the ETT and stylet to the shape of the used laryngoscope blade and retracting the stylet at a similar angle to avoid complications, such as tracheal rupture.

From bench to bar side: Evaluating the red wine storage lesion

Vitally essential red fluids like packed cells and red wine are seriously influenced in quality when stored over prolonged periods. In the case of red cell concentrates, the resulting storage lesion has particular significance in perioperative medicine. We hypothesized that, in contrast, aging rather improves the properties of red wine in several ways. A translational approach, including (I) in vitro experiments, (II) a randomized, blinded crossover trial of acute clinical effects, and (III) a standardized red wine blind tasting was used. Three monovarietal wines (Cabernet Sauvignon, Chianti, Shiraz) in three different vintages (range 2004-2016), each 5 years different, were assessed. Assessments were performed at a German university hospital (I, II) and on a garden terrace during a mild summer evening (III). Young wines induced cell stress and damage while significantly reducing cytoprotective proteins in HepG2 hepatoma cells. Sympathetic activity and multitasking skills were altered depending on wines' ages. Hangovers tended to be aggravated by young red wine. Aged variants performed better in terms of aroma and overall quality but worse in optical appearance. We found no evidence for a red wine storage lesion. However, we plead for consensus-based guidelines for proper storage, as it is common in clinical medicine.

Pediatric emergence delirium is linked to increased early postoperative negative behavior within two weeks after adenoidectomy: an observational study

BACKGROUND

The aim of this prospective multicenter observational study was to measure the incidence of postoperative pediatric emergence delirium and to investigate the occurrence of early postoperative negative behavior within two weeks after outpatient adenoidectomy in preschool children.

METHODS

The study comprised 222 patients (1-7 years of age). All children received a multimodal anesthesia based on total intravenous anesthesia with propofol and remifentanil in combination with piritramid (0.1 mg.kg-1), ibuprofen (10 mg.kg-1), dexamethason (0.15 mg.kg-1), and ketanest S (0.1 mg.kg-1). We evaluated emergence delirium using the Pediatric Anesthesia Emergence Delirium Scale (PAED) at different predefined time points during the recovery period. Emergence delirium was defined as a PAED score ≥ 9 for the first three criteria. Additionally, we defined early postoperative negative behavior to be present when at least 5 of 27 criteria of the post hospitalization behavior questionnaire were positive.

RESULTS

The incidence of emergence delirium following our anesthetic regime was 23%. The incidence of early postoperative negative behavior was significantly higher among patients with emergence delirium (24% vs. 11%, p = 0.04). The two categories, "sleep disturbance" and "separation anxiety", tested within the questionnaire for early postoperative negative behavior, were identified as the most common postoperative negative behavioral changes.

CONCLUSION

Emergence delirium not only plays a role immediately after surgery but is also linked to early postoperative negative behavior within two weeks after outpatient adenoidectomy. Parents should be informed that early postoperative negative behavior may occur in 1 out of 4 patients if emergence delirium was present postoperatively.

TRIAL REGISTRATION

DRKS - German Clinical Trial Register ID: DRKS00013121.

Emergence delirium in children: a Brazilian survey

Background

Pediatric emergence delirium is characterized by a disturbance of a child’s awareness during the early postoperative period that manifests as disorientation, altered attention and perception. The incidence of emergence delirium varies between 18% and 80% depending on risk factors and how it is measured. Reports from Canada, Germany, Italy, United Kingdom, and France demonstrated a wide range of preventive measures and definitions, indicating that there is a lack of clarity regarding emergence delirium. We aimed to assess the practices and beliefs among Brazilian anesthesiologists regarding emergence delirium.

Methods

A web-based survey was developed using REDCap®. A link and QR Code were sent by email to all Brazilian anesthesiologists associated with the Brazilian Society of Anesthesiology (SBA).

Results

We collected 671 completed questionnaires. The majority of respondents (97%) considered emergence delirium a relevant adverse event. Thirty-two percent of respondents reported routinely administrating medication to prevent emergence delirium, with clonidine (16%) and propofol (15%) being the most commonly prescribed medications. More than 70% of respondents reported a high level of patient and parent anxiety, a previous history of emergence delirium, and untreated pain as risk factors for emergence delirium. Regarding treatment, thirty-five percent of respondents reported using propofol, followed by midazolam (26%).

Conclusion

Although most respondents considered emergence delirium a relevant adverse event, only one-third of them routinely applied preventive measures. Clonidine and propofol were the first choices for pharmacological prevention. For treatment, propofol and midazolam were the most commonly prescribed medications.

Relative cerebral hyperperfusion during cardiopulmonary bypass is associated with risk for postoperative delirium: a cross-sectional cohort study

Background

Our objective was to evaluate if changes in on-pump cerebral blood flow, relative to the pre-bypass baseline, are associated with the risk for postoperative delirium (POD) following cardiac surgery.

Methods

In 47 consecutive adult patients, right middle cerebral artery blood flow velocity (MCAV) was assessed using transcranial Doppler sonography. Individual values, measured during cardiopulmonary bypass (CPB), were normalized to the pre-bypass baseline value and termed MCAV_rel. An MCAV_rel > 100% was defined as cerebral hyperperfusion. Prevalence of POD was assessed using the Confusion Assessment Method for the Intensive Care Unit.

Results

Overall prevalence of POD was 27%. In the subgroup without POD, 32% of patients had experienced relative cerebral hyperperfusion during CPB, compared to 67% in the subgroup with POD (p < 0.05). The mean averaged MCAV_rel was 90 (±21) % in the no-POD group vs. 112 (±32) % in the POD group (p < 0.05), and patients developing delirium experienced cerebral hyperperfusion during CPB for about 39 (±35) min, compared to 6 (±11) min in the group without POD (p < 0.001). In a subcohort with pre-bypass baseline MCAV (MCAV_bas) below the median MCAV_bas of the whole cohort, prevalence of POD was 17% when MCAV_rel during CPB was kept below 100%, but increased to 53% when these patients actually experienced relative cerebral hyperperfusion.

Conclusions

Our results suggest a critical role for cerebral hyperperfusion in the pathogenesis of POD following on-pump open-heart surgery, recommending a more individualized hemodynamic management, especially in the population at risk.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0705-y) contains supplementary material, which is available to authorized users.

[Drama in the Recovery Unit: Paediatric Emergence Delirium]

The upcoming and ongoing debate on neurotoxicity of anesthetics at a young age put a new spotlight on the emergence delirium of children (paedED). The European Society for Anesthesiology published a consensus guideline on prevention and therapy in 2017 which can be a useful guidance in daily clinical practice. Patient data management systems with their clear documentation concerning pain/therapy of pain and paedED will be valuable tools in order to assess the real incidence of paedED. Differentiating between pain/agitation and paedED migth not always be easy. Age-adapted scores should always be applied. Main focus in the prevention of paedED is the reduction of anxiety. The way this is achieved by the dedicated pediatric anesthesia teams caring for children, e.g. by oral midazolam, clowns, music, smartphone induction, does not matter. Using α₂-agonists in the perioperative phase and applying propofol seems to be effective. A quiet supportive environment for recovery adds to a relaxed, stress-free awakening. For the future detecting paedED on normal wards becomes an important issue. This may be achieved by structured interviews or questionnaires assessing postoperative negative behavioural changes at the same time.

Oxycodone is safe and effective for general anesthesia

PURPOSE

In clinical practice, using different opioid analgesics is common during the induction and maintenance of general anesthesia and for postoperative analgesia. However, if the opioid analgesic could be limited to a single drug, we hypothesized that the risk of adverse drug interactions could be reduced, with fewer adverse effects. We examined the use of oxycodone as a single opioid in a well-defined cohort of orthopedic patients undergoing general anesthesia.

METHODS

In this retrolective, monocentric investigation, we reviewed data from 83 patients who underwent general anesthesia and received intravenous oxycodone as the sole analgesic (0.075 mg/kg during induction and 0.05 mg/kg during maintenance). The use of oxycodone during general anesthesia and the postoperative pain scores were recorded. Safety was evaluated by the measurement of hemodynamic changes (blood pressure, heart rate), the detection of pathologic changes in the electrocardiogram, changes of the peripheral oxygen saturation, and by the assessment of adverse effects.

RESULTS

There was no significant change in peripheral oxygen saturation or the electrocardiogram during or while recovering from general anesthesia. Heart rate changed only slightly from reversal to recovery (73.3/min versus 78.3/min, p < 0.05) and from prior intubation to recovery (72.5/min versus 78.3/min, p < 0.05). Systolic and diastolic blood pressure did not change significantly from the time points "after intubation" to "after incision," and "during recovery." Fifty-nine percent (n = 49) of patients' records revealed pain scores with a maximum of 3 on a numeric rating scale (NRS) of 0 to10 during the postoperative period. In 45 percent of patients (n = 37), further analgesics such as acetaminophen, dipyrone, or additional doses of oxycodone were used. No severe adverse events were recorded. According to data from 93 percent of patients (n = 77), nausea scores were less than 3 on a NRS of 0 to 10.

CONCLUSION

Oxycodone can be used as the sole opioid in orthopedic surgery with good intra- and postoperative efficacy and safety; ie, without clinically relevant changes in hemodynamic and respiratory parameters.

Oxycodone is safe and effective for general anesthesia

PURPOSE

In clinical practice, using different opioid analgesics is common during the induction and maintenance of general anesthesia and for postoperative analgesia. However, if the opioid analgesic could be limited to a single drug, we hypothesized that the risk of adverse drug interactions could be reduced, with fewer adverse effects. We examined the use of oxycodone as a single opioid in a well-defined cohort of orthopedic patients undergoing general anesthesia.

METHODS

In this retrolective, monocentric investigation, we reviewed data from 83 patients who underwent general anesthesia and received intravenous oxycodone as the sole analgesic (0.075 mg/kg during induction and 0.05 mg/kg during maintenance). The use of oxycodone during general anesthesia and the postoperative pain scores were recorded. Safety was evaluated by the measurement of hemodynamic changes (blood pressure, heart rate), the detection of pathologic changes in the electrocardiogram, changes of the peripheral oxygen saturation, and by the assessment of adverse effects.

RESULTS

There was no significant change in peripheral oxygen saturation or the electrocardiogram during or while recovering from general anesthesia. Heart rate changed only slightly from reversal to recovery (73.3/min versus 78.3/min, p < 0.05) and from prior intubation to recovery (72.5/min versus 78.3/min, p < 0.05). Systolic and diastolic blood pressure did not change significantly from the time points "after intubation" to "after incision," and "during recovery." Fifty-nine percent (n = 49) of patients' records revealed pain scores with a maximum of 3 on a numeric rating scale (NRS) of 0 to10 during the postoperative period. In 45 percent of patients (n = 37), further analgesics such as acetaminophen, dipyrone, or additional doses of oxycodone were used. No severe adverse events were recorded. According to data from 93 percent of patients (n = 77), nausea scores were less than 3 on a NRS of 0 to 10.

CONCLUSION

Oxycodone can be used as the sole opioid in orthopedic surgery with good intra- and postoperative efficacy and safety; ie, without clinically relevant changes in hemodynamic and respiratory parameters.

Cerebral Function and Perfusion during Cardiopulmonary Bypass: A Plea for a Multimodal Monitoring Approach

Background: Postoperative neurological injury still represents a major cause of morbidity after cardiac surgery. Our objective was to compare the limits as well as advantages of routine monitoring tools for the detection of cerebral function and perfusion deficits during cardiopulmonary bypass in a daily clinical setting.Methods: Adult patients undergoing elective cardiac surgery with use of cardiopulmonary bypass were included. Patients received monitoring comprising Bispectral Index (BIS), Near Infrared Spectroscopy (NIRS) and assessment of middle cerebral artery flow velocity (MCAV) using transcranial Doppler (TCD) sonography. Measurements were taken after anesthesia induction (at baseline) and every 10 minutes during aortic cross-clamping. Relative deviation from baseline values was calculated. Values were compared with predefined, generally accepted threshold values identifying patients at risk for cerebral functional and perfusion deficits.Results: 30 consecutive patients were included into data analysis. Compared to NIRS as well as BIS monitoring, there was a wide interindividual variability in relative MCAV values for the whole cohort (median 0.9, range 0.39-2.19). Out of 229 measurements in total, 82 BIS but only 30 NIRS and 12 TCD values were lying outside predefined limits. TCD monitoring identified two patients with disturbed cerebral autoregulation, while NIRS remained unremarkable. The latter was significantly associated with systemic hemoglobin levels. Finally, patients with relative MCAV values >1.0 had a higher risk of developing postoperative delirium.Conclusion: Our findings reveal inherent technical limitations of each individual monitoring component, such as high interindividual variability (TCD), low spatial resolution (NIRS), or interaction with anesthetics (BIS). We therefore argue for a multimodal neuromonitoring that combines several qualities. Such approach would help reducing these limitations while individual components complement each other, thus providing more patient safety during cardiac surgery. Furthermore, such an approach would be easily applicable in a routine clinical setting.

The provision of pediatric cardiac anesthesia services in Germany: current status of structural and personnel organization

BACKGROUND

Anesthesia for pediatric cardiac surgery requires a high level of expert knowledge. There are currently no recommendations and standards for anesthetic management for congenital cardiac surgery in Germany.

AIM

The aim of the present study was to assess the current status of structural and personnel anesthetic standards at pediatric cardiac surgery centers in Germany.

METHODS

All cardiac surgical centers in Germany were reviewed for an active program for congenital heart surgery. Centers with an active program were invited to respond to an online survey. The questionnaire containing 55 items in 16 categories assessed current practice in pediatric cardiac anesthesia.

RESULTS

An active program for pediatric cardiac surgery was identified at 27 centers. The response rate to the survey was 96.3%. A specialized group of anesthesiologists for pediatric cardiac anesthesia was reported from 26 centers (92.3%). The mean size of this group was 4.8 anesthesiologists per center. However, the annual case load of centers and relative annual case load per specialized anesthesiologist varied considerably between 12.5 and 250. Nonanesthesiologists performed sedation and general anesthesia for diagnostic and therapeutic interventions outside the operating theater in children with congenital heart diseases in 24 centers (77%). Although special equipment, for example, pediatric TEE, near-infrared spectroscopy, and devices for mechanical auto transfusion were available in most centers, their routine use was not always part of standard operating procedures. The proposal for mean adequate training in pediatric cardiac anesthesia as estimated by the participating centers was 10.8 months.

CONCLUSION

The present study represents the current structural situation for anesthesia at German pediatric cardiac surgery centers.

Prevention and Therapy of Pediatric Emergence Delirium: A National Survey

INTRODUCTION

Although pediatric emergence delirium (ED) is common, preventive and therapeutic pharmacological treatment is the matter of an international controversial discussion and evidence on different options is partially vague.

OBJECTIVE

We therefore examined clinical routine in prevention strategies and postoperative therapy of ED with respect to clinical experience in pediatric anesthesia.

METHODS

A web-based survey was developed investigating routine management (prevention and treatment) of ED, facility structure, and patient population. The link was sent to all enlisted members of the German Society of Anesthesiology.

RESULTS

We analyzed 1229 questionnaires. Overall, 88% reported ED as a relevant clinical problem; however, only 5% applied assessment scores to define ED. Oral midazolam was reported as standard premedication by 84% of respondents, the second largest group was 'no premedication' (5%). The first choice prevention strategy was to perform total intravenous (propofol) anesthesia (63%). The first choice therapeutic pharmacological treatment depended on clinical experience. Therapeutic propofol was preferentially chosen by more experienced anesthesiologists (5 to >20 patients per week, n = 538), while lesser experienced colleagues (<5 patients per week, n = 676) preferentially applied opioids. Dexmedetomidine (1%) and non-pharmacological (2%) therapy were rarely stated. The highest satisfaction levels for pharmacological therapy of ED were attributed to propofol.

CONCLUSIONS

Propofol is the preferred choice for pharmacological prevention and treatment of ED among German anesthesiologists. Further therapy options as well as alternatives to a midazolam-centered premedication procedure are underrepresented.

A Model to Simulate Clinically Relevant Hypoxia in Humans

In case of apnea, arterial partial pressure of oxygen (pO2) decreases, while partial pressure of carbon dioxide (pCO2) increases. To avoid damage to hypoxia sensitive organs such as the brain, compensatory circulatory mechanisms help to maintain an adequate oxygen supply. This is mainly achieved by increased cerebral blood flow. Intermittent hypoxia is a commonly seen phenomenon in patients with obstructive sleep apnea. Acute airway obstruction can also result in hypoxia and hypercapnia. Until now, no adequate model has been established to simulate these dynamics in humans. Previous investigations focusing on human hypoxia used inhaled hypoxic gas mixtures. However, the resulting hypoxia was combined with hyperventilation and is therefore more representative of high altitude environments than of apnea. Furthermore, the transferability of previously performed animal experiments to humans is limited and the pathophysiological background of apnea induced physiological changes is poorly understood. In this study, healthy human apneic divers were utilized to mimic clinically relevant hypoxia and hypercapnia during apnea. Additionally, pulse-oximetry and Near Infrared Spectroscopy (NIRS) were used to evaluate changes in cerebral and peripheral oxygen saturation before, during, and after apnea.

[Emergence delirium in children - prophylaxis and treatment]

Emergence Delirium in children after general anesthesia is a common and self limitating event. Although it might be seen as being harmless it can cause other serious complications and might leave both parents and other caregivers with a negative impression behind. Although the cause may still not be clear, potential predictors can be named: preschool age, the use of fast acting volatile anesthestics, higher preoperative anxiety levels and postoperative pain.A child-focused approach to reduce preoperative anxiety focusing on distraction methods rather than pharmacological sedation may be the key as well as sufficient postoperative pain control and the use of total intravenous anesthesia. Parenteal presence during induction of anaesthesia (PPIA) may be beneficial to reduce preoperative anxiety levels, but has failed to prove a better outcome regarding ED.The use of age adopted scores/scales to diagnose ED and Pain are mandatory.In the case of an ED event it is most important to protect the child from self injury and the loss of the iv-line. Postoperative pian needs to be ruled out before treating ED. Most cases can be treated by interrupting the situation and putting the child "back to sleep". Short acting drugs as Propofol have been used successfully due to its pharmacodynamics and short acting profile. Alternatively alpha-agonists or ketamin may be preferred by other authors. If potential predictors and a positive history are present, prophylactic treatment should be considered. A TIVA or the use of alpha-2-agonists have proven to be successful in reducing the risk of an ED. Midazolam may reduce preoperative anxiety but not the incidence of ED and should therefore be used carefully and is not a good choice in PACU for the treatment of ED.Parents who witnessed ED in their children should be guided and followed up. Explaining this phenomenon to parents beforehand should be part of the pre anaesthesia clinic talk and written consent.Standard protocols should be in place for treatment in the postoperative period.

Human plasmacytoid dentritic cells elicit a Type I Interferon response by sensing DNA via the cGAS-STING signaling pathway

Plasmacytoid dendritic cells (pDCs) are a major source of type I interferon (IFN) and are important for host defense by sensing microbial DNA via TLR9. pDCs also play a critical role in the pathogenesis of IFN-driven autoimmune diseases. Yet, this autoimmune reaction is caused by the recognition of self-DNA and has been linked to TLR9-independent pathways. Increasing evidence suggests that the cytosolic DNA receptor cyclic GMP-AMP (cGAMP) synthase (cGAS) is a critical component in the detection of pathogens and contributes to autoimmune diseases. It has been shown that binding of DNA to cGAS results in the synthesis of cGAMP and the subsequent activation of the stimulator of interferon genes (STING) adaptor to induce IFNs. Our results show that the cGAS-STING pathway is expressed and activated in human pDCs by cytosolic DNA leading to a robust type I IFN response. Direct activation of STING by cyclic dinucleotides including cGAMP also activated pDCs and knockdown of STING abolished this IFN response. These results suggest that pDCs sense cytosolic DNA and cyclic dinucleotides via the cGAS-STING pathway and that targeting this pathway could be of therapeutic interest.

The Use of Internal Jugular Vein Ultrasonography to Anticipate Low or High Central Venous Pressure During Mechanical Ventilation

BACKGROUND

Critically low or high central venous pressure (CVP) values, together with systemic hypotension, can indicate hypovolemia or acute heart failure. However, measuring CVP requires the insertion of a central venous catheter, a time-consuming procedure that can be associated with severe complications.

OBJECTIVE

We sought to evaluate the use of ultrasonography of the internal jugular vein (IJV) to estimate low or high CVP values in patients who were on ventilation.

METHODS

Ultrasonography of IJV dimensions and the collection of hemodynamic data was performed in 47 patients, and the ratio between IJV diameter in the 30° and 0° position was calculated (ratio(30/0)). The predictive value of ratio(30/0) for estimating low and high CVP levels was analyzed using receiver operating characteristic curves.

RESULTS

The median IJV diameter ratio(30/0) was 0.49. CVP ranged from 1 to 13 mm Hg (median 7 mm Hg). Seventeen patients had a CVP ≤ 5 mm Hg or lower (defined as "low"), and in 11 patients, values of ≥ 10 mm Hg were measured (defined as "high"). The corresponding IJV diameter ratios increased significantly from 0.34 (in the low CVP group) to 0.9 (in the high CVP group). Receiver operating characteristic analysis revealed a good predictive value of the ratio(30/0) for the prediction of low or high CVP values, respectively. A ratio(30/0) of < 0.45 optimally indicated a low CVP, while > 0.65 was the cutoff value to detect a CVP ≥ 10 mm Hg.

CONCLUSION

The estimation of low or high CVP values by IJV ultrasonography in different patient positions can be a helpful instrument for the rapid hemodynamic assessment of the critically ill patient.

Intraoperative burst suppression is associated with postoperative delirium following cardiac surgery: a prospective, observational study

Background

Postoperative delirium (POD) occurs frequently after cardiac surgery and is associated with increased morbidity and mortality. We analysed whether perioperative bilateral BIS monitoring may detect abnormalities before the onset of POD in cardiac surgery patients.

Methods

In a prospective observational study, 81 patients undergoing cardiac surgery were included. Bilateral Bispectral Index (BIS)-monitoring was applied during the pre-, intra- and postoperative period, and BIS, EEG Asymmetry (ASYM), and Burst Suppression Ratio (BSR) were recorded. POD was diagnosed according to the Confusion Assessment Method for the Intensive Care Unit, and patients were divided into a delirium and non-delirium group.

Results

POD was detected in 26 patients (32%). A trend towards a lower ASYM was observed in the delirium group as compared to the non-delirium group on the preoperative day (ASYM = 48.2 ± 3.6% versus 50.0 ± 4.7%, mean ± sd, p = 0.087) as well as before induction of anaesthesia, with oral midazolam anxiolysis (median ASYM = 49.5%, IQR [47.4;51.5] versus 50.6%, IQR [49.1;54.2], p = 0.081). Delirious patients remained significantly (p = 0.018) longer in a burst suppression state intraoperatively (107 minutes, IQR [47;170] versus 44 minutes, IQR [11;120]) than non-delirious patients. Receiver operating analysis revealed burst suppression duration (area under the curve = 0.73, p = 0.001) and BSR (AUC = 0.68, p = 0.009) as predictors of POD.

Conclusions

Intraoperative assessment of BSR may identify patients at risk of POD and should be investigated in further studies. So far it remains unknown whether there is a causal relationship or rather an association between intraoperative burst suppression and the development of POD.

Trial registration

clinicaltrials.gov NCT01048775

Evaluation of near-infrared spectroscopy under apnea-dependent hypoxia in humans

In this study we investigated the responsiveness of near-infrared spectroscopy (NIRS) recordings measuring regional cerebral tissue oxygenation (rSO2) during hypoxia in apneic divers. The goal was to mimic dynamic hypoxia as present during cardiopulmonary resuscitation, laryngospasm, airway obstruction, or the "cannot ventilate cannot intubate" situation. Ten experienced apneic divers performed maximal breath hold maneuvers under dry conditions. SpO2 was measured by Masimo™ pulse oximetry on the forefinger of the left hand. NIRS was measured by NONIN Medical's EQUANOX™ on the forehead or above the musculus quadriceps femoris. Following apnea median cerebral rSO2 and SpO2 values decreased significantly from 71 to 54 and from 100 to 65%, respectively. As soon as cerebral rSO2 and SpO2 values decreased monotonically the correlation between normalized cerebral rSO2 and SpO2 values was highly significant (Pearson correlation coefficient = 0.893). Prior to correlation analyses, the values were normalized by dividing them by the individual means of stable pre-apneic measurements. Cerebral rSO2 measured re-saturation after termination of apnea significantly earlier (10 s, SD = 3.6 s) compared to SpO2 monitoring (21 s, SD = 4.4 s) [t(9) = 7.703, p < 0.001, r(2) = 0.868]. Our data demonstrate that NIRS monitoring reliably measures dynamic changes in cerebral tissue oxygen saturation, and identifies successful re-saturation faster than SpO2. Measuring cerebral rSO2 may prove beneficial in case of respiratory emergencies and during pulseless situations where SpO2 monitoring is impossible.

Comparison between bispectral index and patient state index as measures of the electroencephalographic effects of sevoflurane

BACKGROUND

The Bispectral Index (BIS) and the Patient State Index (PSI) quantify depth of anesthesia by analyzing the electroencephalogram. The authors examined the response of BIS and PSI to sevoflurane anesthesia.

METHODS

In 22 patients, sevoflurane anesthesia was induced by inhalation with a tight-fitting facemask and was maintained via a laryngeal mask. Sevoflurane concentrations were increased until burst suppression occurred and subsequently decreased until BIS recovered to values above 60. This procedure was repeated twice until patients underwent intubation for subsequent surgery. End-tidal sevoflurane concentrations, BIS, and PSI were recorded simultaneously. The performance of PSI and BIS to predict the estimated sevoflurane effect site concentration, as derived from simultaneous pharmacokinetic and pharmacodynamic modeling, was compared by determination coefficients (rho(2)) and prediction probabilities (P(K)).

RESULTS

A significant (P < 0.001) correlation between BIS and PSI was found (r(2) = 0.75), and a close sigmoid relation between sevoflurane effect site concentration and both BIS (rho(2) = 0.84 +/- 0.09) and PSI (rho(2) = 0.85 +/- 0.15) was observed. The maximum sevoflurane electroencephalographic effect resulted in PSI values (1.3 +/- 4.3) that were significantly (P = 0.019) lower than BIS values (7.9 +/- 12.1), and the effect site efflux constant k(e0) was significantly smaller (P = 0.001) for PSI (0.13 +/- 0.08 min(-1)) than for BIS (0.24 +/- 0.15 min(-1)). The probability of BIS (P(K) = 0.80 +/- 0.11) to predict sevoflurane effect site concentration did not differ (P = 0.76) from that of PSI (P(K) = 0.79 +/- 0.09).

CONCLUSIONS

The BIS reacted faster to changes in sevoflurane concentrations, whereas the PSI made better use of the predefined index range. However, despite major differences in their algorithms and minor differences in their dose-response relations, both PSI and BIS predicted depth of sevoflurane anesthesia equally well.

Correlation of the A-Line™ ARX index with acoustically evoked potential amplitude †

BACKGROUND

Automated indices derived from mid-latency auditory evoked potentials (MLAEP) have been proposed for monitoring the state of anaesthesia. The A-Line ARX index (AAI) has been implemented in the A-Line monitor (Danmeter, V1.4). Several studies have reported variable and, in awake patients, sometimes surprisingly low AAI values. The purpose of this study was to reproduce these findings under steady-state conditions and to investigate their causes.

METHODS

Ten awake unmedicated volunteers were studied under steady-state conditions. For each subject, the raw EEG and the AAI were recorded with an A-Line monitor (V1.4) during three separate sessions of 45.0 (1.6) min duration each. MATLAB (Mathworks) routines were used to derive MLAEP responses from EEG data and to calculate maximal MLAEP amplitudes.

RESULTS

The AAI values ranged from 15 to 99, while 11.4% fell below levels which, according to the manufacturer, indicate an anaesthetic depth suitable for surgery. Inter-individual and intra-individual variation was observed despite stable recording conditions. The amplitudes of the MLAEP varied from 0.8 to 42.0 microV. The MLAEP amplitude exceeded 2 microV in 75.3% of readings. The Spearman's rank correlation coefficient between the MLAEP amplitude and the AAI value was r=0.89 (P<0.0001).

CONCLUSIONS

The version of the A-Line monitor used in this study does not exclude contaminated MLAEP signals. Previous publications involving this version of the A-Line monitor (as opposed to the newer A-Line/2 monitor series) should be reassessed in the light of these findings. Before exclusively MLAEP-based monitors can be evaluated as suitable monitors of depth of anaesthesia, it is essential to ensure that inbuilt validity tests eliminate contaminated MLAEP signals.

Reduction in anaesthetic drug consumption is correlated with mean titrated intra-operative Bispectral Index values

BACKGROUND

Several studies have shown a reduction in anaesthetic drug consumption with Bispectral Index (BIS) titration compared with standard clinical practice. However, the amount of reduction varied widely between 1% and 40%. We investigated the correlation between reduction in anaesthetic drug consumption and mean titrated BIS values.

METHODS

An analysis upon randomized controlled trials cited until January 2006 in MEDLINE and other databases investigating the potential reduction in anaesthetic (hypnotic) drug consumption with BIS titration was performed. Investigations with a marked difference (> 15%) in opioid drug consumption between the BIS group and the standard practice group were excluded. Correlations between amount of reduction in hypnotic drug use and the mean titrated BIS value were analysed with linear regression.

RESULTS

Fourteen manuscripts covering 2582 patients were included into the analysis. The mean BIS value in the standard clinical practice group averaged over all studies was 43.6 +/- 3.2 and the mean BIS value in the BIS-titrated group was 49.9 +/- 5.4. The amount of reduction in hypnotic drug use correlated significantly with the mean BIS values in the BIS-titrated groups (r =0.68) and with the differences between the mean BIS value in the BIS-titrated group and the mean BIS value in the standard clinical practice group (r = 0.70). Every point of BIS difference between the two groups resulted in a reduced hypnotic drug use of approximately 2%.

CONCLUSION

Despite differences in the study designs and in the drugs used, a linear correlation between the mean titrated BIS value and the hypnotic drug saving potential was found.

The Correlation of the Bispectral Index with Propofol Effect Site Concentrations is not Altered by Epochs Indicated as Artefact-Loaded by Narcotrend

OBJECTIVE

Artefact detection is an essential feature of automatic EEG monitoring systems used in anaesthesia. Clinical experience indicates that Narcotrend monitoring (MonitorTechnik, Bad Bramstedt, Germany, version 4.0) excludes more EEG epochs because of artefacts than bispectral index monitoring (BIS, Aspect Medical Systems, Newton, MA, version XP). Whether this increased exclusion of epochs is justified has not been investigated yet.

METHODS

Eighteen adult patients undergoing radical prostatectomy were investigated. Induction of anaesthesia was performed with a fentanyl bolus and a propofol infusion. Additionally, following intubation patients received 15 ml bupivacaine 0.5% epidurally. After a waiting period of 45 min depth of anaesthesia was varied two times by increasing and decreasing propofol concentrations. Narcotrend index, BIS values and calculated propofol effect site concentrations were automatically recorded at intervals of 5 s. We tested the hypothesis whether exclusion of artefacts detected by the Narcotrend monitor would possibly improve the prediction probability of the BIS monitor, justifying the necessity of artefact suppression.

RESULTS

Simulated propofol effect site concentrations ranged from 2 microg/ml to 6 microg/ml. The Narcotrend monitor excluded a significantly higher percentage of epochs because of artefact detection (12.6 + 1.0%) than the BIS monitor (0.4 +/- 0.1%). The performance of BIS as an indicator of predicted propofol effect site concentrations did not differ when including (P(K) = 0.86 +/- 0.05) or excluding (P(K) = 0.85 +/- 0.04) the data pairs where Narcotrend monitor but not BIS monitor indicated an artefact. Artefacts were evenly distributed over the investigated range ofpropofol effect site concentrations.

CONCLUSION

Exclusion of data pairs that were detected as artefacts by Narcotrend but not by BIS did not change the performance of bispectral index as an indicator of propofol effect site concentration.

Molecular and functional changes in voltage-dependent Na(+) channels following pilocarpine-induced status epilepticus in rat dentate granule cells

Status epilepticus (S.E.) is known to lead to a large number of changes in the expression of voltage-dependent ion channels and neurotransmitter receptors. In the present study, we examined whether an episode of S.E. induced by pilocarpine in vivo alters functional properties and expression of voltage-gated Na(+) channels in dentate granule cells (DGCs) of the rat hippocampus. Using patch-clamp recordings in isolated DGCs, we show that the voltage-dependent inactivation curve is significantly shifted toward depolarizing potentials following S.E. (half-maximal inactivation at -43.2+/-0.6 mV) when compared with control rats (-48.2+/-0.8 mV, P<0.0001). The voltage-dependent activation curve is significantly shifted to more negative potentials following S.E., with half-maximal activation at -28.6+/-0.8 mV compared with -25.8+/-0.9 mV in control animals (P<0.05). The changes in voltage dependence resulted in an augmented window current due to increased overlap between the activation and inactivation curve. In contrast to Na(+) channel voltage-dependence, S.E. caused no changes in the kinetics of fast or slow recovery from inactivation. The functional changes were accompanied by altered expression of Na(+) channel subunits measured by real-time reverse transcription-polymerase chain reaction in dentate gyrus microslices. We investigated expression of the pore-forming alpha subunits Na(v)1.1-Na(v)1.3 and Na(v)1.5-Na(v)1.6, in addition to the accessory subunits beta(1) and beta(2). The Na(v)1.2 and Na(v)1.6 subunit as well as the beta(1) subunit were persistently down-regulated up to 30 days following S.E. The beta(2) subunit was transiently down-regulated on the first and third day following S.E. These results indicate that differential changes in Na(+) channel subunit expression occur in concert with functional changes. Because coexpression of beta subunits is known to robustly shift the voltage dependence of inactivation in a hyperpolarizing direction, we speculate that a down-regulation of beta-subunit expression may contribute to the depolarizing shift in the inactivation curve following S.E.

Slow recovery from inactivation regulates the availability of voltage-dependent Na(+) channels in hippocampal granule cells, hilar neurons and basket cells

1. Fundamental to the understanding of CNS function is the question of how individual neurons integrate multiple synaptic inputs into an output consisting of a sequence of action potentials carrying information coded as spike frequency. The availability for activation of neuronal Na(+) channels is critical for this process and is regulated both by fast and slow inactivation processes. Here, we have investigated slow inactivation processes in detail in hippocampal neurons. 2. Slow inactivation was induced by prolonged (10-300 s) step depolarisations to -10 mV at room temperature. In isolated hippocampal dentate granule cells (DGCs), recovery from this inactivation was biexponential, with time constants for the two phases of slow inactivation tau(slow,1) and tau(slow,2) ranging from 1 to 10 s and 20 to 50 s, respectively. Both (slow,1) and tau(slow,2) were related to the duration of prior depolarisation by a power law function of the form tau(t) = a (t/a)b, where t is the duration of the depolarisation, a is a constant kinetic setpoint and b is a scaling power. This analysis yielded values of a = 0.034 s and b = 0.62 for tau(slow,1) and a = 24 s and b = 0.30 for tau(slow,2) in the rat. 3. When a train of action potential-like depolarisations of different frequencies (50, 100, 200 Hz) was used to induce inactivation, a similar relationship was found between the frequency of depolarisation and both tau(slow,1) and tau(slow,2) (a = 0.58 s, b = 0.39 for tau(slow,1) and a = 3.77 s and b = 0.42 for tau(slow,2)). 4. Using nucleated patches from rat hippocampal slices, we have addressed possible cell specific differences in slow inactivation. In fast-spiking basket cells a similar scaling relationship can be found (a = 3.54 s and b = 0.39) as in nucleated patches from DGCs (a = 2.3 s and b = 0.48) and non-fast-spiking hilar neurons (a = 2.57 s and b = 0.49). 5. Likewise, comparison of human and rat granule cells showed that properties of ultra-slow recovery from inactivation are conserved across species. In both species ultra-slow recovery was biexponential with both tau(slow,1) and tau(slow,2) being related to the duration of depolarisation t, with a = 0.63 s and b = 0.44 for tau(slow,1) and a = 25 s and b = 0.37 for tau(slow,2) for the human subject. 6. In summary, we describe in detail how the biophysical properties of Na(+) channels result in a complex interrelationship between availability of sodium channels and membrane potential or action potential frequency that may contribute to temporal integration on a time scale of seconds to minutes in different types of hippocampal neurons.