Effect of General Anaesthesia versus Conscious Sedation on Clinical and Procedural Outcome in Patients Undergoing Endovascular Stroke Treatment: A Matched-Pair Analysis.

INTRODUCTION: General anaesthesia (GA) during mechanical thrombectomy (MT) might lead to an inferior clinical outcome compared to conscious sedation (CS). It was hypothesised that using CS might avoid a critical drop in cerebral perfusion, shorten the time of the intervention and therefore might result in better clinical outcome. In this study, we compared the procedural and clinical results of patients who underwent MT under GA or CS at two tertiary neuro-vascular centres on the basis of a matched-pair analysis. METHODS: Using a matched-pair approach, we compared the data of 56 patients that were treated under CS at centre A (n = 28) with selected patients who were treated under GA at the centre B (n = 28). Patients were matched for age, sex, site of vessel occlusion, NIHSS at admission (±3 points), time from symptom onset to initial stroke imaging, intravenous-lysis and co-morbidities. All patients had an ASPECT-score of ≥8. To exclude the effect of technical failures, only patients with successful recanalization of the occluded vessel (TICI 2b and 3) were included into the study. The primary endpoint was the proportion of patients with early good clinical outcome after MT, defined by a modified Ranking Scale (mRS)-score ≤2 at discharge. Secondary endpoints were the time from symptom onset to the start of the procedure, the duration of the procedure and the rate of procedural complications. RESULTS: There were no differences concerning gender, age, the site of vessel occlusion and the degree of stroke severity at baseline. The proportion of patients with an early good clinical outcome (mRS ≤2 at discharge) was 60.4% (17/28) in both groups. The time from symptom onset to the start of the procedure was shorter at centre B, while the duration of the procedure was significantly faster at A, resulting in an overall time from symptom onset to complete recanalization of 152.2 ± 68.0 min for patients treated at centre A and 171.1 ± 43.5 min for patients at centre B (ns). CONCLUSION: Our study revealed no differences in the investigated clinical outcome for patients undergoing endovascular stroke treatment under GA versus CS.

The response of the composite variability index to a standardized noxious stimulus during propofol-remifentanil anesthesia.

BACKGROUND: Recently the Composite Variability Index (CVI) was developed to quantify nociception. This index is derived from the standard deviations (s) of the Bispectral Index (sBIS) and the electromyogram (sEMG). The primary aim of our study was to compare CVI before and after a noxious stimulus. As secondary end points, we investigated the influence of remifentanil on the CVI and tested the ability of the CVI to indicate patient movement after a noxious stimulus under changing remifentanil concentrations. Furthermore, we measured the increase in CVI after a noxious stimulus in comparison to other clinical variables (BIS, sBIS, sEMG, heart rate [HR], and systolic blood pressure [BP(sys)]). METHODS: Twenty-four patients without a history of cardiac disease were investigated. Anesthesia was induced with propofol administered by target-controlled infusion. A standardized noxious electrical stimulus was applied (50 Hz, 70 mA, 30 seconds) to the ulnar nerve at increasing or decreasing remifentanil effect-compartment concentrations (Ce(remi)). Changes in baseline and poststimulus CVI, BIS, sBIS, sEMG, HR, and BP(sys) were investigated. Parameters' ability to indicate movement after a noxious stimulus was evaluated with the prediction probability (P(K)). RESULTS: All investigated parameters (except BP(sys)) increased significantly after a noxious stimulus at 0, 1, 2, or 3 ng·mL(-1) Ce(remi). The association between poststimulus maximal parameters and movement were P(K) = 0.81 for HR, P(K) = 0.78 for sEMG, and P(K) = 0.72 for CVI (pairwise difference to CVI statistically nonsignificant). The association between ΔsEMG or ΔCVI (poststimulus value minus baseline value) and movement was significantly higher (P(K) = 0.76 and 0.75, respectively) compared with ΔHR (P(K) = 0.53) (P = 0.008 and P = 0.01, respectively). Receiver operating characteristic analysis revealed a threshold value for movement for ΔCVI of >0.39 (sensitivity of 0.71, specificity of 0.74) and for ΔsEMG of >0.31 (sensitivity of 0.68, specificity of 0.78). CONCLUSION: In paralyzed patients, ΔsEMG and ΔCVI might help identify inadequately low levels of analgesia with an acceptable sensitivity and specificity. The impact of profound neuromuscular block on the CVI should be investigated in further studies.

Spectral entropy and bispectral index as measures of the electroencephalographic effects of propofol.

Recently, Datex-Ohmeda introduced the Entropy Moduletrade mark for measuring depth of anesthesia. Based on the Shannon entropy of the electroencephalogram, state entropy (SE) and response entropy (RE) are computed. We investigated the dose-response relationship of SE and RE during propofol anesthesia in comparison with the Bispectral Indextrade mark (BIS). Twenty patients were studied without surgical stimulus. Anesthesia was induced by a constant propofol infusion of 2000 mg/h (451 +/- 77 microg x min(-1) x kg(-1)) via a large forearm vein. Propofol was infused until substantial burst suppression occurred (more than 50%) or mean arterial blood pressure decreased to <60 mm Hg. Hereafter, infusions were stopped until recovery of BIS values up to 60 was reached. Subsequently, the constant propofol infusion of 2000 mg/h was restarted to increase depth of anesthesia and again decreased (infusion was stopped) within the BIS value range of 40-60. The coefficient of determination (R2) and the prediction probability (P(K)) were calculated to evaluate the performance of SE, RE, and BIS to predict changing propofol effect-site concentrations. R2 values for SE, RE, and BIS of 0.88 +/- 0.08, 0.89 +/- 0.07, and 0.92 +/- 0.06, respectively, were similar. The calculated P(K) values, however, revealed a significant difference between SE and RE compared with BIS, with P(K) = 0.77 +/- 0.09, 0.76 +/- 0.10, and 0.84 +/- 0.06, respectively. BIS seems to show slight advantages in predicting propofol effect-site concentrations compared with SE and RE, as measured by P(K) but not as measured by R2.

Spectral entropy and bispectral index as measures of the electroencephalographic effects of sevoflurane.

BACKGROUND: Recently, entropy algorithms have been proposed as electroencephalographic measures of anesthetic drug effects. Datex-Ohmeda (Helsinki, Finland) introduced the Entropy Module, a new electroencephalographic monitor designed for measuring depth of anesthesia. The monitor calculates a state entropy (SE) computed over the frequency range of 0.8-32 Hz and a response entropy (RE) computed over the frequency range of 0.8-47 Hz. The authors investigated the dose-response relation of SE and RE during sevoflurane anesthesia in comparison with the Bispectral Index (BIS). METHODS: Sixteen patients were studied without surgical stimulus. Anesthesia was induced by sevoflurane inhalation with a tight-fitting facemask. Sevoflurane concentrations were increased and subsequently decreased and increased two to four times until the measurement was stopped and patients were intubated for surgery. The performances of SE, RE, and BIS to predict the estimated sevoflurane effect site concentration, obtained by simultaneous pharmacokinetic and pharmacodynamic modeling, were compared by calculating the correlation coefficients and the prediction probability. RESULTS: State entropy, RE, and BIS values decreased continuously over the observed concentration range of sevoflurane. Correlation coefficients were slightly but not significantly better for entropy parameters (0.87 +/- 0.09 and 0.86 +/- 0.10 for SE and RE, respectively) than for BIS (0.85 +/- 0.12). Calculating the prediction probability confirmed these results with a prediction probability of 0.84 +/- 0.05 and 0.82 +/- 0.06 for SE and RE, respectively, and 0.80 +/- 0.06 for BIS. CONCLUSION: State entropy and RE seem to be useful electroencephalographic measures of sevoflurane drug effect.