[Comparison of current critical care information systems from the perspective of clinical users : Summary of the results of a German nationwide survey]. / Vergleich aktueller Patientendatenmanagementsysteme in der Intensivmedizin aus Sicht der klinischen Nutzer : Zusammenfassung der Ergebnisse einer deutschlandweiten Umfrage.

BACKGROUND: Critical care information systems (CCIS) are computer-based systems designed to process the growing amount of complex medical data in intensive care units (ICU). Previous studies have shown that CCICs can increase the quality of patient care by reducing errors and improving work efficiency; however, other studies have shown that CCISs can also cause harmful effects by disrupting workflow, facilitating medication errors or increasing charting time. The factors that decide whether a CCIS has a positive or negative impact on patient care are summarized under the term "usability". This article summarizes the results of three previously published papers on this topic. OBJECTIVE: The aim of the study was to identify which CCIS functions were considered useful by clinical ICU staff and how well these functions are implemented in the CCISs currently used in German ICUs. MATERIAL AND METHODS: An online survey was performed targeting nurses and physicians working in German ICUs using a previously validated questionnaire. The questionnaire included a list of functions (36 for physicians/31 for nurses) that were preselected by experts based on a comprehensive model of ICU work processes. Each of these functions was rated by the study participants on a Likert scale ranging from 0 (worst rating) to 5 (best rating) with respect to the usefulness to identify which functions of CCIS can truly be considered as useful by clinical ICU staff. Furthermore, the participants rated how well these functions were implemented in the CCIS currently in use on the ICU, also using a Likert scale of 0-5. Further questions were provided to rate specific technical usability aspects of the CCISs currently in use. In addition, to capture possible confounders the questionnaire recorded 18 individual and workspace characteristics which might influence the ratings. RESULTS: A total of 171 nurses and 741 physicians participated in the survey of which 535 used CCISs. Of the functions 33 were rated as useful for doctors and 28 functions for nurses with median scores between 4 and 5. Participants currently using CCISs gave higher ratings compared to participants not using CCISs. The quality of the functions was rated relatively lower than the usefulness and the availability. Furthermore, currently used CCISs in Germany differ greatly in their technical and task-specific usability. Of the CCISs investigated, the system ICUData had the best overall rating and technical usability followed by the systems ICM and MetaVision. The same three CCIS were rated best in task-specific functions without significant differences between them. CONCLUSION: Those functions that were identified as useful based on the ratings of clinical ICU staff should be implemented in current CCIS. The list of these functions might be regarded as a first step towards providing a catalog of functional requirements for CCISs. Furthermore, as the results show that the quality of the available functions was rated lower than the availability of the functions, manufacturers should shift more of the effort away from the development of new features and focus on improving the user-friendliness and quality of existing functions.

Nociceptive activation in spinal cord and brain persists during deep general anaesthesia.

BACKGROUND: In clinical practice, analgesic drug doses applied during general anaesthesia are considered sufficient when clinical responses (e.g. movement, blood pressure and heart rate elevations) are suppressed during noxious stimulation. We investigated whether absent clinical responses are indicative of suppressed spinal and brain responsiveness to noxious stimulation in anaesthetised subjects. METHODS: Ten healthy volunteers were investigated during deep propofol anaesthesia supplemented with increasing doses of remifentanil in a stepwise manner. Noxious electrical stimuli at an intensity comparable with surgical stimulation were repeatedly administered at each targeted remifentanil concentration. During stimulation, we monitored both clinical responses (blood pressure, heart rate, and movement) and neuronal responses. Neuronal responses were assessed using functional magnetic resonance imaging, spinal reflex responses, and somatosensory evoked potentials. RESULTS: This monitoring combination was able to faithfully detect brain and spinal neuronal responses to the noxious stimulation. Although clinical responses were no longer detected at analgesic dosages similar to those used for general anaesthesia in clinical practice, spinal and brain neuronal responses were consistently observed. Opioid doses that are significantly larger than is usually used in clinical practice only reduced neuronal responses to 41% of their maximal response. CONCLUSIONS: Nociceptive activation persists during deep general anaesthesia despite abolished clinical responses. Absent clinical responses are therefore not indicative of absent nociception-specific activation. Thus, commonly accepted clinical responses might be inadequate surrogate markers to assess anti-nociception during general anaesthesia. Further research is required to investigate whether persistent nociception causes adverse effects on patient outcome.

Higher doses of intraoperative analgesia are associated with lower levels of persistent pain and less analgesic consumption six months after total hip arthroplasty.

BACKGROUND: Persistent postoperative pain is a major health problem affecting nearly 30% of all patients undergoing total hip arthroplasty. Previous studies have demonstrated an association between the intensity of acute postoperative pain and persistent pain, but this association might be an epiphenomenon of insufficient intraoperative analgesia. In this study, we investigated the association between the intraoperative level of analgesia and the persistent postoperative pain 6 months after surgery. METHODS: We investigated 110 patients undergoing primary total hip arthroplasty under total intravenous general anaesthesia in a prospective cohort study. A highly standardized surgical and a standardized anaesthetic procedure were performed to reduce variability and psychosocial influences were investigated to adjust for confounders. Acute postoperative pain was controlled using patient-controlled analgesia pumps. Postoperative pain intensities and analgesic requirements were monitored for 6 months following surgery. RESULTS: Of 105 patients included in the analysis, 32% continued using daily pain medication 6 months after surgery and reported a median pain level of 4/10. Multivariate analyses confirmed that the amount of intraoperative analgesia is a significant predictor of regular analgesic use and pain intensity 6 months after surgery. CONCLUSIONS: Higher levels of intraoperative analgesia are associated with lower levels of persistent pain and less analgesic consumption 6 months after total hip arthroplasty. Persistent pain may be attributable to intraoperative nociception, which is likely not adequately assessed and suppressed using current clinical measures. SIGNIFICANCE: Our study suggests that lower doses of intraoperative analgesia are associated with higher levels of persistent postoperative pain. Persistent pain may be caused by intraoperative nociception, which is likely not adequately suppressed using current clinical standard analgesic measures.

Electroencephalogram dynamics in children during different levels of anaesthetic depth.

OBJECTIVE: Anaesthesia-induced dynamics in EEG are dependent on age and level of anaesthesia, but distinct characterisation in children is incomplete. Here we analyse EEG dynamics in children related to age and level of anaesthesia. METHODS: Frontal EEG recordings were obtained from 93 children (0-19years) during routine clinical anaesthesia. EEG segments were selected at four different levels of anaesthesia: emergence, light anaesthesia, deep anaesthesia, and very deep anaesthesia. RESULTS: Total power differed significantly over age at deep (R2=0.314; p<0.0001) and very deep anaesthesia (R2=0.403; p<0.0001). Relative beta band power at light anaesthesia increased linearly with age (R2=0.239; p<0.0001). Level of anaesthesia caused significant differences for relative delta band power (increasing with anaesthetic depth), for relative beta band power and for spectral edge frequency (decreasing with anaesthetic depth) for all children (p<0.0001). CONCLUSIONS: EEG parameterin children were primary dependent on anaesthetic depth, where beta band power, delta band power and spectral edge frequency showed a linear relation. Age-dependency during anaesthesia procedure were only seen for single EEG parameters. SIGNIFICANCE: Different levels of anaesthesia can be identified by relative beta band power, relative delta band power and spectral edge frequency irrespective of the children's age.

[Monitoring of pain, nociception, and analgesia under general anesthesia: Relevance, current scientific status, and clinical practice]. / Monitoring von Schmerz, Nozizeption und Analgesie unter Allgemeinanästhesie: Relevanz, aktueller wissenschaftlicher Stand und klinische Praxis.

BACKGROUND: To avoid negative effects of painful stimuli under general anesthesia, an adequate analgesia is needed. Since both overdosing and underdosing of analgesics may lead to negative consequences, an optimal dosing is crucial, requiring a continuous monitoring of the balance between the ongoing nociception and the level of analgesia. METHODS: This review describes current methods for the monitoring of nociception and analgesia as well as their inherent differences. RESULTS: Monitors of nociception register organic responses that are triggered through painful stimuli and therefore allow the detection of phases of excessive nociception during inadequate analgesia. In contrast, monitors of analgesia register nociception-specific organic responses that are triggered through test stimuli and allow a preemptive adaption of the level of analgesia, before a painful clinical stimulus is applied, but require the application of test stimuli. Preliminary proof-of-concept studies were able to demonstrate the potential of the here described methods; however, an effect on the clinical outcome of patients has not yet been shown for either of the two types of monitoring. CONCLUSIONS: For the routine application of monitors of nociception and analgesia in daily clinical practice, large clinical studies are necessary, proving a positive outcome effect. Without reliable parameters for nociception and analgesia it was hitherto impossible to perform such studies. The progress made in recent years generates optimism that in the not too distant future the currently available methods to monitor nociception and analgesia might improve to a level of reliability to allow them to be used to investigate the clinical outcome relevance of nociception and analgesia.

Utility of Nociceptive Flexion Reflex Threshold, Bispectral Index, Composite Variability Index and Noxious Stimulation Response Index as measures for nociception during general anaesthesia.

Movement and haemodynamic responses to noxious stimuli during general anaesthesia are regarded as signs of nociception. We compared the Nociceptive Flexion Reflex Threshold (NFRT), Bispectral Index (BIS), Composite Variability Index (CVI), Noxious Stimulation Response Index (NSRI) and the calculated propofol/remifentanil effect-compartment concentrations (Ce) as predictors for such responses in 50 female subjects at laryngeal mask airway insertion and skin incision. The following prediction probabilities (PK-values) were obtained at laryngeal mask airway insertion and skin incision, respectively. For movement responses: NFRT = 0.77 and 0.72; p = 0.0001 and 0.004, respectively; BIS = 0.41 and 0.56, p = 0.29 and 0.5, respectively; CVI = 0.48 and 0.57, p = 0.76 and 0.88, respectively; NSRI = 0.49 and 0.76, p = 0.92 and 0.0001, respectively; propofol-Ce = 0.35 and 0.66, p = 0.04 and 0.03, respectively; remifentanil-Ce = 0.68 and 0.72, p = 0.01 and 0.003, respectively. For heart rate responses: NFRT = 0.68 and 0.75, p = 0.04 and 0.01, respectively; BIS = 0.37 and 0.59, p = 0.15 and 0.41, respectively; CVI = 0.41 and 0.44, p = 0.39 and 0.37, respectively; NSRI = 0.48 and 0.53, p = 0.84 and 0.78, respectively; propofol-Ce = 0.42 and 0.56, p = 0.39 and 0.53, respectively; remifentanil-Ce = 0.58 and 0.54, p = 0.35 and 0.73, respectively. We conclude that the NFRT best predicts movement and heart rate responses to noxious stimuli. Effect-compartment concentrations and NSRI also predict movement (but not heart rate) responses satisfactorily.

Sevoflurane reduces spinal reciprocal Ia-inhibition in humans.

BACKGROUND: Potentiation of inhibitory transmissions in the spinal cord is considered to be an important mechanism for the mediation of the immobilizing effects of anesthetics. However, the depressant effects on motoneurons could be counterbalanced by presynaptic effects that inhibit the depressant pathways. Here we investigated the effect of sevoflurane on a disynaptic inhibitory pathway onto motoneurons in a human reflex model. METHODS: The study was performed with 9 volunteers receiving sevoflurane anesthesia (end tidal: 0.8% sevoflurane). Reciprocal inhibition was estimated from the depression of the H-reflex following a conditioning stimulation of the muscle spindle afferents from the tibialis anterior muscle. Measurements were performed before, during and after drug administration. RESULTS: The inhibition (mean ± SE) amounted to 15.4% ± 6.8%, 1.9% ± 4.2% and 15.7% ± 8.8% for measurements before, during and after sevoflurane administration, respectively. Differences between the anesthetic state and the two controls were statistically significant (mixed-effect ANOVA, p<0.01). CONCLUSION: Sevoflurane reduces reciprocal Ia-inhibition on motoneurons in humans. These findings seem to contradict the accepted view that sevoflurane enhances inhibitory synaptic transmission. This contradiction might be explained by the inhibitory actions of sevoflurane within the disynaptic pathway prior to the final glycinergic transmission onto the motoneuron. Our results suggest that even in presumably simple pathways, postsynaptic effects of anesthetics could be superimposed by their presynaptic effects.

Monitoring of the responsiveness to noxious stimuli during sevoflurane mono-anaesthesia by using RIII reflex threshold and bispectral index.

BACKGROUND: We investigated the accuracy of the (normalized) RIII reflex threshold, the bispectral index (BIS), and the end-tidal sevoflurane concentration for predicting movement responses during mono-anaesthesia using sevoflurane. METHODS: Fourteen male subjects were included. Each received a sevoflurane mono-anaesthesia for which the end-tidal concentration was increased in steps of 0.2 vol% every 10 min. Every 5 min, the reactions to noxious stimuli (10 s trapezius squeeze and 30 s 80 mA tetanic stimulus) were tested. The administration of sevoflurane was halted after no movement reactions occurred for three concentration steps. RIII reflex threshold and BIS were recorded continually in all subjects. RESULTS: Thirteen subjects completed the study. The prediction probabilities for movement reactions to the noxious stimuli were 0.79 for the BIS, 0.91 for the RIII threshold, and 0.89 for the end-tidal sevoflurane concentration (PKDMACRO-Statistics: BIS vs RIII, P<0.05; BIS vs C(sevo), P<0.05; RIII vs C(sevo), P>0.05). All population prediction probability values differed significantly from 0.5 (P<0.01, PKDMACRO). CONCLUSIONS: All three instruments can be used for a prediction of movement responses to a noxious stimulus under sevoflurane mono-anaesthesia with an accuracy exceeding prediction by chance. The accuracy of the BIS to predict these responses appears to be lower compared with the RIII reflex threshold or the end-tidal sevoflurane concentration.

Monitoring of the responsiveness to noxious stimuli during anaesthesia with propofol and remifentanil by using RIII reflex threshold and bispectral index.

BACKGROUND: Movement responses are an important indicator of noxious perception in the unconscious state. To allow for a continual monitoring of the responsiveness to noxious stimuli during general anaesthesia, surrogate parameters are needed. Here we compare the performance of the bispectral index (BIS) and the RIII threshold in predicting reactions to noxious stimuli during anaesthesia with propofol and remifentanil. METHODS: Twenty male volunteers were included. The first 10 subjects received constant concentrations of propofol while remifentanil concentrations were increased stepwise. The other 10 subjects each received high propofol concentrations combined with different low remifentanil concentrations and also low propofol concentrations combined with different high remifentanil concentrations. In all subjects, the reactions to an 80 mA 30 s tetanic stimulus were tested every 5 min. BIS and RIII threshold were recorded continually in all subjects. RESULTS: Nineteen subjects completed the study. The population prediction probability for reactions to the noxious stimuli amounted to 0.86 for the BIS and to 0.84 for the RIII threshold in the first 10 subjects (P>0.05, PKDMACRO). In the other nine subjects, the prediction probabilities amounted to 0.64 for the BIS and to 0.77 for the RIII threshold (P<0.05, PKDMACRO). All population prediction probability values differed significantly from 0.5 (P<0.01, PKDMACRO). CONCLUSIONS: RIII threshold and BIS are both influenced dose-dependently by remifentanil at those concentrations that suppress reactions to noxious stimuli. The susceptibility of the parameters to remifentanil concentration seems to be of a similar quality. Under different ratios of propofol and remifentanil concentrations, the RIII threshold correlates with non-responsiveness better than the BIS.

Comparison of the nociceptive flexion reflex threshold and the bispectral index as monitors of movement responses to noxious stimuli under propofol mono-anaesthesia.

BACKGROUND: Prediction of movement responses to noxious stimuli during anaesthesia is of clinical importance. Susceptibility of a parameter of immobility to both hypnotic and analgesic influences could pose an advantage. Here, nociceptive reflexes might be useful, but data regarding the suppression by hypnotic substances are scarce. Therefore, we compared the prediction of movement responses by the RIII reflex threshold and the bispectral index (BIS) during propofol mono-anaesthesia. METHODS: Fifteen male volunteers were included. Propofol effect compartment concentration was increased every 15 min in steps of 1 microg ml(-1) (max 7 microg ml(-1)). Every 5 min, the reactions to trapezius squeezes and 30 s tetanic stimulations (80 mA) of the right ulnar nerve were tested. The RIII reflex threshold was estimated continuously using an automated threshold tracking system that analyses the nociceptive RIII response at the left biceps femoris muscle to stimulation of the left sural nerve. RESULTS: Twelve subjects completed the study. RIII threshold values were normalized by subtraction of the first threshold that was estimated after the subject's loss of consciousness. The population prediction probability P(K) amounted to 0.84 for the RIII threshold and to 0.86 for the BIS (difference not significant). CONCLUSIONS: Movement responses to noxious stimuli under propofol can be predicted by the RIII threshold with a comparable accuracy as the BIS. Therefore, the RIII threshold seems to be influenced by hypnotic effects. Since susceptibility of the RIII threshold to analgesic influences is well established, an advantage for the RIII threshold in the prediction of motor responses could be expected when analgesic substances are used in addition to propofol.