The German version of the Critical-Care Pain Observation Tool for critically ill adults : A prospective validation study.

BACKGROUND: The implementation of the Critical-Care Pain Observation tool (CPOT) in intensive care units (ICU) has been associated with more frequent pain assessments, a reduced number of complications, and improved administration of analgesics and sedatives. So far no German translation exists. Translating this tool into foreign languages requires further validation testing. OBJECTIVE: The aim of this prospective observational validation study was to translate the original version of the CPOT according to scientific principles for translation and to establish the validity and reliability of the German translation of CPOT for critically ill adult patients. MATERIAL AND METHODS: A total of 292 cardiac surgery patients from 2 ICUs of 2 German university teaching hospitals were included (114 patients at center 1 and 178 patients at center 2). Of the included patients 22.6% were female and 76.4% were male with a mean age of 68.5 years ±9.3 SD. Pain was evaluated with the CPOT, the Bhavioral Pain Scale (BPS) and with the Numeric Rating scale (NRS) at three time points (1. intubated + sedated, 2. intubated + awake, 3. extubated + awake) at rest and during nociceptive stimulus (positioning). Assessments were made separately by trained physicians and nursing staff. RESULTS: Good results for interrater reliability and internal consistency could be demonstrated (weighted Cohen's kappa of 0.73, Cronbach's coefficient alpha of 0.8). Spearman correlation between CPOT and NRS was moderate but significant. The receiver operating characteristic (ROC) analysis to obtain optimal thresholds of CPOT to detect pain revealed different results during rest and stimulus and in intubated and extubated patients. CONCLUSION: The validated German CPOT translation is a reliable tool for pain assessment in cardiac ICU patients in the absence of patients' ability for self-reporting. The use of this German version of CPOT now allows a better international comparability of corresponding data in future studies.

Burst suppression-MAC and burst suppression-CP50 as measures of cerebral effects of anaesthetics.

BACKGROUND: MAC (minimum alveolar concentration of an inhaled anaesthetic) and CP50i (minimum plasma concentration of i.v. anaesthetics) are well-established measures to compare potencies of anaesthetics. The underlying clinical endpoint immobility reflects mainly effects of anaesthetics on the spinal cord, which limits the use of this measure for comparison of effects on the main target organ of general anaesthesia--the brain. The present study determines the median concentration of sevoflurane, isoflurane, and propofol that induce the onset of electroencephalogram (EEG) suppression ('silent second'): MACBS and CP50BS. METHODS: Fifty-five unpremedicated patients (ASA physical status of I or II) undergoing elective surgery were randomly assigned to receive general anaesthesia with sevoflurane, isoflurane, or propofol. A two-channel EEG was continuously recorded to identify 'silent second'. Independent cross-over pairs were analysed using the 'Dixon's up-and-down' method, and MACBS/CP50BS values were calculated by logistic regression. RESULTS: CP50BS was 4.9 µg ml(-1) for propofol. MACBS was 2.9 vol% for sevoflurane and 1.5 vol% for isoflurane. CP50BS of propofol was less than one-third of CP50i, whereas MACBS of sevoflurane was >1.4-fold of MAC; MACBS of isoflurane was 1.3-fold of MAC. CONCLUSIONS: Immobility and cerebral effects reflect different entities of anaesthetic action. The median concentration of anaesthetic drug (volatile or i.v. agent) required to induce 'silent second' might be a more useful metric than the median concentration required to prevent movement in response to a surgical stimulus in order to compare relative potencies of anaesthetic agents on the brain. Advantage of the 'silent second' is an easy identification of this endpoint, while such a deep level is not required for clinical anaesthesia.

Time delay of electroencephalogram index calculation: analysis of cerebral state, bispectral, and Narcotrend indices using perioperatively recorded electroencephalographic signals.

BACKGROUND: Monitoring of anaesthetic depth with EEG-derived indices may detect EEG changes associated with awareness and thereby help to decrease the incidence of intraoperative awareness with postoperative recall. All currently available monitors need varying time periods to calculate a new index when reacting to changes in anaesthetic depth. The exact time delay for calculation of new index values is unknown. In a previous study, we used simulated EEG signals and found considerable time lags for the cerebral state index (Danmeter, Odense, Denmark), the bispectral index (Aspect Medical Systems Inc., Newton, MA, USA), and the Narcotrend index (MonitorTechnik, Bad Bramstedt, Germany). The aim of this study was to investigate whether the time delays observed with simulated EEG signals also applied to real EEG data. METHODS: We used perioperatively recorded EEG data from a database corresponding to the awake state, general anaesthesia, and suppression of cortical activity, respectively. After a switch from one state of consciousness to another, the time necessary for all indices to adjust the index value to the underlying input signal was measured. RESULTS: We found time delays for all indices between 24 (7) and 122 (23) s before the new state was indicated. In accordance with our previous results, these time delays were not constant and depended on the particular starting and target index value. Results were different for decreasing and increasing values. CONCLUSIONS: Our results may show a limitation of the value of electronic EEG indices in prevention of awareness with recall. Furthermore, due to different time delays for ascending and descending values, the results of pharmacodynamic studies may be influenced by this phenomenon.

Transcranial motor evoked potentials during anesthesia with desflurane versus propofol--A prospective randomized trial.

OBJECTIVE: This study aimed to evaluate differences in transcranial electrical motor evoked potential (tcMEP) amplitudes between desflurane/remifentanil and propofol/remifentanil anesthesia treatment plans in patients without preexisting motor deficits (PMDs) undergoing carotid endarterectomy (CEA). METHODS: This prospective trial included 21 patients who were randomly assigned to an effect group (Group(DESFLURANE); n=14) or a control group (Group(STANDARD-PROPOFOL); n=7). tcMEP amplitudes were measured 35 min post-induction (T1) either with desflurane or propofol. Treatment was then changed to propofol in Group(DESFLURANE). After an additional 35 min, the tcMEP amplitudes were reevaluated (T2). Differences in amplitudes (DW) between T1 and T2 were calculated for each patient, and the means of these differences were compared between groups. RESULTS: tcMEPs were recorded in all 21 patients. At T1, the mean amplitude was 840.1 (SD 50.3) µV and 358.9 (SD 74) µV for Group(STANDARD-PROPOFOL) and Group(DESFLURANE), respectively. The absolute mean difference (T1-T2) between groups was -496.75 µV (p=0.0006). CONCLUSION: Desflurane reduces the tcMEP amplitude significantly more than propofol in patients without PMDs undergoing CEA. SIGNIFICANCE: TcMEPs were recorded in all patients regardless of the anesthesia regimen. In patients with initially small amplitudes, desflurane may limit tcMEP recording because it produces a remarkable amplitude reduction, even in patients without PMDs.

Monitors of the hypnotic component of anesthesia - correlation between bispectral index and cerebral state index.

BACKGROUND: The current study examines whether analysis of identical EEG data results in a high correlation coefficient of BIS and CSI values during all anesthetic levels and assesses the concordance of both EEG monitors for displaying the level of anesthesia as defined by the manufacturers. METHODS: EEG data of 40 patients undergoing elective surgery under general anesthesia with either sevoflurane/remifentanil or propofol/remifentanil were replayed to an EEG player and reanalysed by a BIS A-2000® monitor and a Cerebral State Monitor. Further, research into differences between CSI and BIS index values was performed, e.g., extraction of differences of ≥ 10 and ≥ 20 index points and of the EEG length with differing index values. RESULTS: The overall correlation coefficient was 0.68 without significant difference between propofol or sevoflurane group. In 51.8% of all recordings, both EEG monitors agreed in their classification of the anesthetic level. The number and length of differing index pairs was influenced by varying time delays of index calculation and different algorithms of index computation. CONCLUSION: In contrast to previous studies, our current approach combines the following conditions: analysis on basis of identical underlying EEG data from deep to light anesthesia, no guidance of anesthetic administration by one of the EEG-based monitors, avoidance of simultaneous EEG readings and the use of two different anesthetic regimens. Though the result of EEG analysis during anesthesia is similar with both monitors, CSI performance during propofol anesthesia was superior to sevoflurane anesthesia. Consequently, a lower agreement of classification of anesthetic levels between BIS and CSI was reached with the use of sevoflurane. Thus, CSI calculation seems not to be independent from anesthetic agent.