Effect of Extracerebral Contamination on Near-infrared Spectroscopy as Revealed during Organ Donation: A Prospective Observational Study in Brain-dead Organ Donors.

BACKGROUND: Near-infrared spectroscopy (NIRS) has been utilized widely in anesthesia and intensive care to monitor regional cerebral oxygen saturation (rScO2). A normal oxygenation of extracerebral tissues may overlay and thereby mask cerebral desaturations, a phenomenon known as extracerebral contamination. The authors investigated the effect of a cessation of extracerebral tissue perfusion on rScO2 in patients with anoxic brains. METHODS: In a single-center, prospective, observational study, brain-dead adults undergoing organ donation were investigated. rScO2 was measured bifrontally using the INVOS 5100C/7100 as well as the ForeSight Elite system. To achieve an efficient conservation of organs and to prevent a redistribution of the perfusion fluid to other tissues, the aorta was clamped before organ perfusion. rScO2 was monitored until at least 40 min after aortic clamping. The primary outcome was the amount of extracerebral contamination as quantified by the absolute decrease in rScO2 after aortic clamping. Secondary outcomes were the absolute rScO2 values obtained before and after clamping. RESULTS: Twelve organ donors were included. Aortic clamping resulted in a significantly (P < 0.001) greater absolute decrease in rScO2 when comparing the INVOS (43.0 ± 9.5%) to the ForeSight (27.8 ± 7.1%) monitor. Before aortic clamping, near-normal rScO2 values were obtained by the INVOS (63.8 ± 6.2%) and the ForeSight monitor (67.7 ± 6.5%). The rScO2 significantly (P < 0.001) dropped to 20.8 ± 7.8% (INVOS) and 39.9 ± 8.1% (ForeSight) 30 min after clamping, i.e., a condition of a desaturation of both extracerebral and cerebral tissues. CONCLUSIONS: The abrupt end of extracerebral contamination, caused by aortic clamping, affected both NIRS monitors to a considerable extent. Both the INVOS and the ForeSight monitor were unable to detect severe cerebral hypoxia or anoxia under conditions of normal extracerebral oxygenation. While both NIRS monitors may guide measures to optimize arterial oxygen supply to the head, they should not be used with the intention to detect isolated cerebral desaturations.

Single-centre real-life observational study on mortality and outcomes: decompressive craniectomy and brain death in traumatic brain injury, haemorrhage, and other cerebral diseases.

BACKGROUND: Decompressive hemicraniectomy (DHC) is used after severe brain damages with elevated, refractory intracranial pressure (ICP). In a non age-restricted population, mortality rates and long-term outcomes following DHC are still unclear. This study's objectives were to examine both, as well as to identify predictors of unfavourable outcomes. METHODS: We undertook a retrospective observational analysis of patients aged 18 years and older who underwent DHC at the University Hospital of Bonn between 2018 and 2020, due to traumatic brain injury (TBI), haemorrhage, tumours or infections. Patient outcomes were assessed by conducting telephone interviews, utilising questionnaires for modified Rankin Scale (mRS) and extended Glasgow Outcome scale (GOSE). We evaluated the health-related quality of life using the EuroQol (EQ-5D-5L) scale. RESULTS: A total of 144 patients with a median age of 58.5 years (range: 18 to 85 years) were evaluated. The mortality rate was 67%, with patients passing away at a median of 6.0 days (IQR [1.9-37.6]) after DHC. Favourable outcomes, as assessed by the mRS and GOSE were observed in 10.4% and 6.3% of patients, respectively. Cox regression analysis revealed a 2.0% increase in the mortality risk for every year of age (HR = 1.017; 95% CI [1.01-1.03]; p = 0.004). Uni- and bilateral fixed pupils were associated with a 1.72 (95% CI [1.03-2.87]; p = 0.037) and 3.97 (95% CI [2.44-6.46]; p < 0.001) times higher mortality risk, respectively. ROC-analysis demonstrated that age and pupillary reactivity predicted 6-month mortality with an AUC of 0.77 (95% CI [0.69-0.84]). The only parameter significantly associated with a better quality of life was younger age. CONCLUSIONS: Following DHC, mortality remains substantial, and favourable outcomes occur rarely. Particularly in elderly patients and in the presence of clinical signs of herniation, mortality rates are notably elevated. Hence, the indication for DHC should be set critically.

How Large is the Potential of Brain Dead Donors and what Prevents Utilization? A Multicenter Retrospective Analysis at Seven University Hospitals in North Rhine-Westphalia.

Organ donation after brain death is constantly lower in Germany compared to other countries. Instead, representative surveys show a positive attitude towards donation. Why this does not translate into more donations remains questionable. We retrospectively analyzed all potential brain dead donors treated in the university hospitals of Aachen, Bielefeld, Bonn, Essen, Düsseldorf, Cologne and Münster between June 2020 and July 2021. 300 potential brain dead donors were identified. Donation was utilized in 69 cases (23%). Refused consent (n = 190), and failed utilization despite consent (n = 41) were reasons for a donation not realized. Consent was significantly higher in potential donors with a known attitude towards donation (n = 94) compared to a decision by family members (n = 195) (49% vs. 33%, p = 0.012). The potential donor´s age, status of interviewer, and the timing of the interview with decision-makers had no influence on consent rates, and it was comparable between hospitals. Refused consent was the predominant reason for a donation not utilized. Consent rate was lower than in surveys, only a known attitude towards donation had a significant positive influence. This indicates that survey results do not translate well into everyday clinical practice and promoting a previously documented decision on organ donation is important.

Anesthesia-induced loss of consciousness disrupts auditory responses beyond primary cortex.

Despite its ubiquitous use in medicine, and extensive knowledge of its molecular and cellular effects, how anesthesia induces loss of consciousness (LOC) and affects sensory processing remains poorly understood. Specifically, it is unclear whether anesthesia primarily disrupts thalamocortical relay or intercortical signaling. Here we recorded intracranial electroencephalogram (iEEG), local field potentials (LFPs), and single-unit activity in patients during wakefulness and light anesthesia. Propofol infusion was gradually increased while auditory stimuli were presented and patients responded to a target stimulus until they became unresponsive. We found widespread iEEG responses in association cortices during wakefulness, which were attenuated and restricted to auditory regions upon LOC. Neuronal spiking and LFP responses in primary auditory cortex (PAC) persisted after LOC, while responses in higher-order auditory regions were variable, with neuronal spiking largely attenuated. Gamma power induced by word stimuli increased after LOC while its frequency profile slowed, thus differing from local spiking activity. In summary, anesthesia-induced LOC disrupts auditory processing in association cortices while relatively sparing responses in PAC, opening new avenues for future research into mechanisms of LOC and the design of anesthetic monitoring devices.

Pupillary Pain Index Predicts Postoperative Pain but Not the Effect of Peripheral Regional Anaesthesia in Patients Undergoing Total Hip or Total Knee Arthroplasty: An Observational Study.

Background and Objectives: The pupillary pain index (PPI) allows the evaluation of intraoperative nociception by measuring pupillary reaction after a localized electrical stimulus. It was the objective of this observational cohort study to investigate the pupillary pain index (PPI) as a method to evaluate the fascia iliaca block (FIB) or adductor canal block (ACB) sensory areas during general anaesthesia in orthopaedic patients with lower-extremity joint replacement surgery. Materials and Methods: Orthopaedic patients undergoing hip or knee arthroplasty were included. After anaesthesia induction, patients received an ultrasound-guided single-shot FIB or ACB with 30 mL and 20 mL of 0.375% ropivacaine, respectively. Anaesthesia was maintained with isoflurane or propofol/remifentanil. The first PPI measurements were performed after anaesthesia induction and before block insertion, the second at the end of surgery. Pupillometry scores were evaluated in the area of the femoral or saphenous nerve (target) and C3 dermatome (control). Primary outcomes were differences between PPIs before and after peripheral block insertion as well as the relationship between PPIs and postoperative pain scores; secondary outcomes were the relationship between PPIs and opioid requirements after surgery. Results: PPI decreased significantly from the first to the second measurement (4.17 ± 2.7 vs. 1.6 ± 1.2, p < 0.001 for target; 4.46 ± 2.7 vs. 2.17 ± 2.1, p < 0.001 for control). Control and target measurements did not show significant differences. A linear regression analysis showed that early postoperative pain scores could be predicted with intraoperative piritramide with improved prediction after adding PPI scores, PCA opioids and surgery type. Forty-eight-hour pain scores at rest and in movement were correlated with intraoperative piritramide and control PPI after the PNB in movement and with second-postoperative-day opioids and target PPI scores before block insertion, respectively. Conclusions: While the effect of an FIB and ACB could not be shown with PPI postoperative pain scores due to a large effect of opioids, perioperative PPI was shown to be associated with postoperative pain. These results suggest that preoperative PPI may be used to predict postoperative pain.

Influence of Intraoperative Nociception during Hip or Knee Arthroplasty with Supplementary Regional Anaesthesia on Postoperative Pain and Opioid Consumption.

Background and Objectives: Early postoperative mobilization is central for postoperative outcomes after lower extremity joint replacement surgery. By providing adequate pain control, regional anaesthesia plays an important role for postoperative mobilization. It was the objective of this study to investigate the use of the nociception level index (NOL) to determine the effect of regional anaesthesia in hip or knee arthroplasty patients undergoing general anaesthesia with additional peripheral nerve block. Materials and Methods: Patients received general anaesthesia, and continuous NOL monitoring was established before anaesthesia induction. Depending on the type of surgery, regional anaesthesia was performed with a Fascia Iliaca Block or an Adductor Canal Block. Results: For the final analysis, 35 patients remained, 18 with hip and 17 with knee arthroplasty. We found no significant difference in postoperative pain between hip or knee arthroplasty groups. NOL increase at the time of skin incision was the only parameter associated with postoperative pain measured using a numerical rating scale (NRS > 3) after 24 h in movement (-12.3 vs. +119%, p = 0.005). There was no association with intraoperative NOL values and postoperative opioid consumption, nor was there an association between secondary parameters (bispectral index, heart rate) and postoperative pain levels. Conclusions: Intraoperative NOL changes may indicate regional anaesthesia effectiveness and could be associated with postoperative pain levels. This remains to be confirmed in a larger study.

Risk assessment of perioperative neurocognitive disorders, where are we now?

PURPOSE OF REVIEW: Perioperative neurocognitive disorders (PNDs) are among the most frequent complications after surgery and are associated with considerable morbidity and mortality. We analysed the recent literature regarding risk assessment of PND. RECENT FINDINGS: Certain genetic variants of the cholinergic receptor muscarinic 2 and 4, as well as a marked degree of frailty but not the kind of anaesthesia (general or spinal) are associated with the risk to develop postoperative delirium (POD). Models predict POD with a discriminative power, for example, area under the receiver operating characteristics curve between 0.52 and 0.94. SUMMARY: Advanced age as well as preexisting cognitive, functional and sensory deficits remain to be the main risk factors for the development of PND. Therefore, aged patients should be routinely examined for both preexisting and new developing deficits, as recommended in international guidelines. Appropriate tests should have a high discrimination rate, be feasible to be administered by staff that do not require excessive training, and only take a short time to be practical for a busy outpatient clinic. Models to predict PND, should be validated appropriately (and externally if possible) and should not contain a too large number of predictors to prevent overfitting of models.

Controlled arterial hypotension during resection of cerebral arteriovenous malformations.

BACKGROUND: Resection of cerebral arteriovenous malformations (AVM) is technically demanding because of size, eloquent location or diffuse nidus. Controlled arterial hypotension (CAH) could facilitate haemostasis. We performed a study to characterize the duration and degree of CAH and to investigate its association with blood loss and outcome. METHODS: We retrospectively analysed intraoperative arterial blood pressure of 56 patients that underwent AVM-resection performed by the same neurosurgeon between 2003 and 2012. Degree of CAH, AVM size, grading and neurological outcome were studied. Patients were divided into two groups, depending on whether CAH was performed (hypotension group) or not (control group). RESULTS: The hypotension group consisted of 28 patients, which presented with riskier to treat AVMs and a higher Spetzler-Martin grading. CAH was achieved by application of urapidil, increasing anaesthetic depth or a combination thereof. Systolic and mean arterial blood pressure were lowered to 82 ± 7 and 57 ± 7 mmHg, respectively, for a median duration of 58 min [25% percentile: 26 min.; 75% percentile: 107 min]. In the hypotension group, duration of surgery (4.4 ± 1.3 h) was significantly (p <  0.001) longer, and median blood loss (500 ml) was significantly (p = 0.002) higher than in the control group (3.3 ± 0.9 h and 200 ml, respectively). No case fatalities occurred. CAH was associated with a higher amount of postoperative neurological deficits. CONCLUSIONS: Whether CAH caused neurological deficits or prevented worse outcomes could be clarified by a prospective randomised study, which is regarded as ethically problematic in the context of bleeding. CAH should only be used after strict indication and should be applied as mild and short as possible.

Dynamic changes of angiopoietins and endothelial nitric oxide supply during fluid resuscitation for major gyn-oncological surgery: a prospective observation.

BACKGROUND: Despite goal-directed hemodynamic therapy, vascular function may deteriorate during surgery for advanced abdominal tumor masses. Fluid administration has been shown to be associated with distinct changes in serum levels of functional proteins. We sought to determine how serum total protein and angiopoietin (ANG) levels change during major abdominal tumor surgery. In addition, ex vivo endothelial nitric oxide synthase (eNOS) activation as well as NO bioavailability in vivo were assessed. METHODS: 30 patients scheduled for laparotomy for late-stage ovarian or uterine cancer were prospectively included. Advanced hemodynamic monitoring as well as protocol-driven goal-directed fluid optimization were performed. Total serum protein, ANG-1, -2, and soluble TIE2 were determined pre-, intra-, and postoperatively. Phosphorylation of eNOS was assessed in microvascular endothelial cells after incubation with patient serum, and microvascular reactivity was determined in vivo by near-infrared spectroscopy and arterial vascular occlusion. RESULTS: Cardiac output as well as preload gradually decreased during surgery and were associated with a median total fluid intake of 12.8 (9.7-15.4) mL/kg*h and a postoperative fluid balance of 6710 (4113-9271) mL. Total serum protein decreased significantly from baseline (66.5 (56.4-73.3) mg/mL) by almost half intraoperatively (42.7 (36.8-51.5) mg/mL, p < 0.0001) and remained at low level. While ANG-1 showed no significant dilutional change (baseline: 12.7 (11.9-13.9) ng/mL, postop.: 11.6 (10.8 -13.5) ng/mL, p = 0.06), serum levels of ANG-2 were even increased postoperatively (baseline: 2.2 (1.6-2.6) ng/mL vs. postop.: 3.4 (2.3-3.8) ng/mL, p < 0.0001), resulting in a significant shift in ANG-2 to ANG-1 ratio. Ex vivo phosphorylation of eNOS was decreased depending on increased ANG-2 levels and ANG-2/1 ratio (Spearman r = - 0.37, p = 0.007). In vivo, increased ANG-2 levels were associated with impaired capillary recruitment and NO bioavailability (Spearman r = - 0.83, p = 0.01). CONCLUSIONS: Fluid resuscitation-associated changes in serum vascular mediator profile during abdominal tumor surgery were accompanied by impaired eNOS activity ex vivo as well as reduced NO bioavailability in vivo. Our results may explain disturbed microvascular function in major surgery despite goal-directed hemodynamic optimization.

Accuracy of the non-invasive Tcore™ temperature monitoring system to measure body core temperature in abdominal surgery.

An accurate determination of body core temperature is crucial during surgery in order to avoid and treat hypothermia, which is associated with poor outcome. In a prospective observational study, we evaluated the suitability of the Tcore™ device (Drägerwerk AG & Co. KGaA, Lübeck, Germany)-a non-invasive thermometer-to accurately determine core body temperature. In patients undergoing surgery for ovarian cancer, core body temperature (CBT) was determined with the Tcore™ sensor attached to the forehead and compared with blood temperature (Tblood) as measured within the femoro-iliacal artery. Both temperatures were recorded every 10 s and the measurement error was calculated. 57,302 data pairs of CBT and Tblood were obtained in 22 patients. In a repeated-measurements version of the Bland and Altman test, a bias of - 0.02 °C and 95% limits of agreement of - 0.48 to 0.44 °C were calculated. In a population analysis, a median absolute error of 0 [- 0.1; + 0.1] °C, a bias of 0 [- 0.276; 0.271] % and an inaccuracy of 0.276 [0.274; 0.354] % was determined. Although the Tcore™ sensor was attached to the frontal skin, it provided an accurate measurement of core body temperature in the investigated intraoperative setting.

Network of Mediators for Vascular Inflammation and Leakage Is Dysbalanced during Cytoreductive Surgery for Late-Stage Ovarian Cancer.

BACKGROUND: Cytoreductive surgery (CS) in late-stage ovarian cancer patients is often challenging due to extensive volume shifts, and high fluid intake may provoke postoperative complications. Expression of vasoactive mediators is altered in cancer patients, which may affect systemic vascular function. We sought to assess how serum levels of vasoactive markers and mediators change during CS in ovarian cancer. METHODS: Following IRB approval and informed consent, pre- and postoperative serum samples were analyzed in 26 late-stage ovarian cancer patients using multiplex protein arrays and ELISA. RESULTS: The proinflammatory cytokines and chemokines IL-6, IL-8, and CCL2 were significantly elevated after 24 hrs compared to the baseline values, with IL-6 and IL-8 being most prominently increased. While ANGPT1 remained unchanged after surgery, its competitive antagonist ANGPT2 was significantly increased. In contrast, serum levels of the ANGPT receptor TIE2 were decreased to 0.6 of the baseline values. While VEGF-D, E-selectin, P-selectin, ICAM-1, and PECAM-1 remained unchanged, serum activity of both thrombomodulin and syndecan-1 was significantly increased following surgery. CONCLUSION: We identified a regulatory network of acute-phase reaction during CS in late-stage ovarian cancer. This suggests that IL-6 exerts positive regulation of other proinflammatory mediators and, by upregulating ANGPT2 and suppressing ANGPT1, induces a serum profile that promotes vascular leakage. This may contribute to the observed hemodynamic alterations during CS procedures.

Near Infrared Spectroscopy Based Clinical Algorithm Applicability During Spinal Neurosurgery and Postoperative Cognitive Disturbances.

Background and Objectives: Postoperative cognitive disturbances (POCD) can significantly alter postoperative recovery. Inadequate intraoperative cerebral oxygen supply is one of the inciting causes of POCD. Near-infrared spectroscopy (NIRS) devices monitor cerebral oxygen saturation continuously and can help to guide intraoperative patient management. The aim of the study was to evaluate the applicability of the NIRS-based clinical algorithm during spinal neurosurgery and to find out whether it can influence postoperative cognitive performance. Materials and Methods: Thirty four patients scheduled for spinal neurosurgery were randomized into a study group (n = 23) and a control group (n = 11). We monitored regional cerebral oxygen saturation (rScO2) throughout surgery, using a NIRS device (INVOS 4100). If rScO2 dropped bilaterally or unilaterally by more than 20% from baseline values, or under an absolute value of 50%, the NIRS-based algorithm was initiated in the study group. In the control group, rScO2 was monitored blindly. To evaluate cognitive function, Montreal-Cognitive Assessment (MoCA) scale was used in both groups before and after the surgery. Results: In the study group, rScO2 dropped below the threshold in three patients and the NIRS-based algorithm was activated. Firstly, we verified correct positioning of the head; secondly, we increased mean systemic arterial pressure in the three patients by injecting repeated intravenous bolus doses of Ephedrine, ultimately resulting in an rScO2 increase above the approved threshold level. None of the three patients showed POCD. In the control group, one patient showed a drop in rScO2 of 34% from baseline and presented with a POCD. RScO2 drop occurred with other stable intraoperative measurements. Conclusions: A significant rScO2 drop may occur during spinal surgery in prone position despite other intraoperative measurements remaining stable, allowing it to stay otherwise unrecognized. Use of the NIRS-based clinical algorithm can help to avoid POCD in patients after spinal surgery.

Anesthesia for electroconvulsive therapy.

PURPOSE OF REVIEW: Electroconvulsive therapy (ECT) is a well established and effective therapy in treatment-resistant depression. It is performed under general anesthesia, but no consensus exists regarding the optimal anesthetic drugs. A growing interest in optimizing adjunctive medication regimes in ECT anesthesia has emerged in recent years. Moreover different methods of seizure induction have been evaluated. RECENT FINDINGS: Pretreatment with dexmedetomidine eased the propofol injection pain and reduced the hyperdynamic response to ECT, but prolonged recovery. Remifentanil exhibited no proconvulsive effect and had no effect on seizure quality. Ketamine showed an antidepressive effect but was associated with cardiovascular side effects and an increased recovery time. A bispectral index-guided anesthesia or a time delay between anesthesia and seizure induction resulted in a better seizure quality presumably by avoiding high concentrations of (anticonvulsive) hypnotics. Seizure induction by magnetism seems to be an alternative to ECT, as the former is associated with less cognitive side effects but comparable antidepressive efficacy. SUMMARY: The current practice of anesthesia for ECT should not be modified, as the evidence of studies is either too low or the results are inconsistent. Some approaches are promising but require validation in further studies with a higher number of participants.

Degree of Postictal Suppression Depends on Seizure Induction Time in Magnetic Seizure Therapy and Electroconvulsive Therapy.

OBJECTIVES: Anesthesia is required for both magnetic seizure therapy (MST) and electroconvulsive therapy (ECT), although it has anticonvulsant properties. In this case, bispectral index (BIS) monitoring, a specific electroencephalogram-derived monitoring, can be used to find the optimal seizure induction time during anesthesia to elicit adequate seizures. A measurement of seizure adequacy in electroencephalogram is the postictal suppression. The purpose of this study was to investigate the influence of seizure induction time on the degree of postictal suppression by comparing BIS versus no-BIS monitoring in MST and ECT. METHODS: Twenty patients with treatment-resistant depression were randomly assigned to either MST or ECT. Each patient underwent 3 treatments with the determination of seizure induction time by defined prestimulation BIS (BIS condition) and 3 treatments with determination of seizure induction time by controlled clinical trial protocol (no-BIS condition). Statistical analysis was calculated by repeated-measures analysis of variance. RESULTS: The degree of postictal suppression was more pronounced in both MST and ECT, with BIS monitoring. In this connection, no differences between MST and ECT were found. Seizure induction time was significantly later in the BIS condition (181.3 ± 6 seconds) compared with the no-BIS condition (114.3 ± 12 seconds) (P < 0.001). CONCLUSIONS: Adequacy of seizures, in the form of the degree of postictal suppression, was superior by determining the seizure induction time with BIS in both MST and ECT. Further research is needed to investigate the correlation between the degree of postictal suppression and treatment response.

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.

Anaesthetic and ICU management of aneurysmal subarachnoid haemorrhage: a survey of European practice.

BACKGROUND: Many aspects of the perioperative management of aneurysmal subarachnoid haemorrhage (SAH) remain controversial. It would be useful to assess differences in the treatment of SAH in Europe to identify areas for improvement. OBJECTIVE: To determine the clinical practice of physicians treating SAH and to evaluate any discrepancy between practice and published evidence. DESIGN: An electronic survey. PARTICIPANTS: Physicians identified through each national society of neuroanaesthesiology and neurocritical care. INTERVENTIONS: A 31-item online questionnaire was distributed by the ENIG group. Questions were designed to investigate anaesthetic management of SAH and diagnostic and treatment approaches to cerebral vasospasm. The survey was available from early October to the end of November 2012. RESULTS: Completed surveys were received from 268 respondents, of whom 81% replied that aneurysm treatment was conducted early (within 24 h). Sixty-five percent of centres treated more than 60% of SAH by coiling, 19% had high-volume clipping (>60% of aneurysms clipped) and 16% used both methods equally. No clear threshold for arterial blood pressure target was identified during coiling, temporary clipping or in patients without vasospasm after the aneurysm had been secured. Almost all respondents used nimodipine (97%); 21% also used statins and 20% used magnesium for prevention of vasospasm. A quarter of respondents used intra-arterial vasodilators alone, 5% used cerebral angioplasty alone and 48% used both endovascular methods to treat symptomatic vasospasm. In high-volume clipping treatment centres, 58% of respondents used endovascular methods to manage vasospasm compared with 86% at high-volume coiling treatment centres (P < 0.001). The most commonly used intra-arterial vasodilator was nimodipine (82%), but milrinone was used by 23% and papaverine by 19%. More respondents (44%) selected 'triple-H' therapy over hypertension alone (30%) to treat vasospasm. CONCLUSION: We found striking variability in the practice patterns of European physicians involved in early treatment of SAH. Significant differences were noted among countries and between high and low-volume coiling centres.

Comparison of propofol pharmacokinetic and pharmacodynamic models for awake craniotomy: A prospective observational study.

BACKGROUND: Anaesthesia for awake craniotomy aims for an unconscious patient at the beginning and end of surgery but a rapidly awakening and responsive patient during the awake period. Therefore, an accurate pharmacokinetic/pharmacodynamic (PK/PD) model for propofol is required to tailor depth of anaesthesia. OBJECTIVE: To compare the predictive performances of the Marsh and the Schnider PK/PD models during awake craniotomy. DESIGN: A prospective observational study. SETTING: Single university hospital from February 2009 to May 2010. PATIENTS: Twelve patients undergoing elective awake craniotomy for resection of brain tumour or epileptogenic areas. INTERVENTION: Arterial blood samples were drawn at intervals and the propofol plasma concentration was determined. MAIN OUTCOME MEASURES: The prediction error, bias [median prediction error (MDPE)] and inaccuracy [median absolute prediction error (MDAPE)] of the Marsh and the Schnider models were calculated. The secondary endpoint was the prediction probability PK, by which changes in the propofol effect-site concentration (as derived from simultaneous PK/PD modelling) predicted changes in anaesthetic depth (measured by the bispectral index). RESULTS: The Marsh model was associated with a significantly (P = 0.05) higher inaccuracy (MDAPE 28.9 ± 12.0%) than the Schnider model (MDAPE 21.5 ± 7.7%) and tended to reach a higher bias (MDPE Marsh -11.7 ± 14.3%, MDPE Schnider -5.4 ± 20.7%, P = 0.09). MDAPE was outside of accepted limits in six (Marsh model) and two (Schnider model) of 12 patients. The prediction probability was comparable between the Marsh (PK 0.798 ± 0.056) and the Schnider model (PK 0.787 ± 0.055), but after adjusting the models to each individual patient, the Schnider model achieved significantly higher prediction probabilities (PK 0.807 ± 0.056, P = 0.05). CONCLUSION: When using the 'asleep-awake-asleep' anaesthetic technique during awake craniotomy, we advocate using the PK/PD model proposed by Schnider. Due to considerable interindividual variation, additional monitoring of anaesthetic depth is recommended. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT 01128465.

Safety, feasibility and complications during resective pediatric epilepsy surgery: a retrospective analysis.

BACKGROUND: Resective epilepsy surgery is an established and effective method to reduce seizure burden in drug-resistant epilepsy. It was the objective of this study to assess intraoperative blood loss, transfusion requirements and the degree of hypothermia of pediatric epilepsy surgery in our center. METHODS: Patients were identified by our epilepsy surgery database, and data were collected via retrospective chart review over the past 25 years. Patients up to the age of 6 years were included, and patients with insufficient data were excluded. RESULTS: Forty-five patients with an age of 3.2 ± 1.6 (mean ± SD) years and a body weight of 17 [14; 21.5] kg (median [25%, 75% percentile]) were analysed. Duration of surgery was 3 h 49 min ± 53 min, which was accompanied by an intraoperative blood loss of 150 [90; 300] ml. This corresponded to 11.7 [5.2; 21.4] % of estimated total blood volume, ranging from 0 to 75%. A minimal haemoglobin count of 8.8 ± 1.4 g/dl was measured, which was substituted with erythrocyte concentrate (100 [0; 250] ml) in 23 patients. Body core temperature dropped from 36.0 ± 0.7°C at baseline to a minimum of 35.7 ± 0.7°C, and increased significantly (p < 0.001) thereafter to 37.1 ± 0.7°C until the end of surgery. A significant (p = 0.0003) correlation between duration of surgery and blood loss (Pearson r = 0.52) was observed. However, age, minimal body temperature or number of antiepileptic drugs seemed to have no impact on blood loss. CONCLUSION: Resective epilepsy surgery is a safe procedure even in the pediatric population, however it is associated with significant blood loss especially during long surgical procedures.

Fractal Analysis of the Cerebrovascular System Pathophysiology.

The cerebrovascular system is characterized by parameters such as arterial blood pressure (ABP), cerebral perfusion pressure (CPP), and cerebral blood flow velocity (CBFV). These are regulated by interconnected feedback loops resulting in a fluctuating and complex time course. They exhibit fractal characteristics such as (statistical) self-similarity and scale invariance which could be quantified by fractal measures. These include the coefficient of variation, the Hurst coefficient H, or the spectral exponent α in the time domain, as well as the spectral index ß in the frequency domain. Prior to quantification, the time series has to be classified as either stationary or nonstationary, which determines the appropriate fractal analysis and measure for a given signal class. CBFV was characterized as a nonstationary (fractal Brownian motion) signal with spectral index ß between 2.0 and 2.3. In the high-frequency range (>0.15 Hz), CBFV variability is mainly determined by the periodic ABP variability induced by heartbeat and respiration. However, most of the spectral power of CBFV is contained in the low-frequency range (<0.15 Hz), where cerebral autoregulation acts as a low-pass filter and where the fractal properties are found. Cerebral vasospasm, which is a complication of subarachnoid hemorrhage (SAH), is associated with an increase in ß denoting a less complex time course. A reduced fractal dimension of the retinal microvasculature has been observed in neurodegenerative disease and in stroke. According to the decomplexification theory of illness, such a diminished complexity could be explained by a restriction or even dropout of feedback loops caused by disease.

Post-COVID-19 pandemic organ donation activities in Germany: a multicenter retrospective analysis.

Introduction: The COVID-19 pandemic had a negative impact on the number of solid organ transplantations. After a global decline of 16% in 2020, their numbers subsequently returned to pre-pandemic levels. In contrast, numbers in Germany remained almost constant in 2020 and 2021 but fell by 6.9% in 2022. The reasons for this divergent development are unknown. Methods: The number of deceased with a severe brain damage, potential and utilized donors after braindeath and the intensive care unit treatment capacity were retrospectively compared for the years 2022 and 2021 at five university hospitals in North Rhine-Westphalia, Germany. Reasons for a donation not utilized were reviewed. To enable a comparison of the results with the whole of Germany and the pre-pandemic period, numbers of potential and utilized donors were extracted from official organ donation activity reports of all harvesting hospitals in Germany for the years 2019-2022. Results: The numbers of deceased with a severe brain damage (-10%), potential (-9%), and utilized donors after braindeath (-44%), and intensive care unit treatment capacities (-7.2%) were significantly lower in 2022 than 2021. A COVID-19 infection was a rarer (-79%), but donor instability (+44%) a more frequent reason against donation in 2022, whereas preserved brain stem reflexes remained the most frequent reason in both years (54%). Overall numbers of potential and utilized donations in Germany were lower in 2022 than in the pre-pandemic period, but this was mainly due to lower numbers in hospitals of lower care. The number of potential donors in all university hospitals were higher in 2022 but utilized donations still lower than in 2019. Conclusion: The decrease in potential and utilized donations was a result of reduced intensive care unit treatment capacities and a lower conversion rate at the five university hospitals. A COVID-19 infection did not play a role in 2022. These results indicate that ICU treatment capacities must be restored to increase donations. The lower number of potential donors and the even lower conversion rate in 2022 throughout Germany show that restructuring the organ procurement process in Germany needs to be discussed to increase the number of donations.