Short-Latency Positive Peak Following N20 Somatosensory Evoked Potential Is Superior to N20 in Predicting Neurologic Outcome After Out-of-Hospital Cardiac Arrest

Enhanced analysis of somatosensory evoked potentials at 20-30 milliseconds can predict neurological outcome after cardiac arrest

OBJECTIVE

This study attempted to test the effectiveness of an enhanced analysis of the 20-30 ms complex of somatosensory evoked potentials, in predicting the short-term outcome of comatose survivors of out of hospital cardiac arrest and compare it with the current clinical practice.

METHODS

Single-centre, prospective, observational study. Median nerve SSEP recording performed at 24-36 h post-return of spontaneous circulation. Recording was analysed using amplitude measurements of P25/30 and Peak-To-Trough of 20-30 ms complex and thresholds to decide P25/30 presence. Neurological outcome was dichotomised into favourable and unfavourable.

RESULTS

89 participants were analysed. 43.8% had favourable and 56.2% unfavourable outcome. The sensitivity, specificity, positive and negative predictive values of the present SSEP and favourable outcome were calculated. P25/30 presence and size of PTT improved positive predictive value and specificity, while maintained similar negative predictive value and sensitivity, compared to the current practice. Inter-interpreter agreement was also improved.

CONCLUSIONS

Enhanced analysis of the SSEP at 20-30 ms complex could improve the short-term prognostic accuracy for short-term neurological outcome in comatose survivors of cardiac arrest.

SIGNIFICANCE

Peak-To-Trough analysis of the 20-30 ms SSEP waveform appears to be the best predictor of neurological outcome following out of hospital cardiac arrest. It is also the easiest and most reliable to analyse.

Short-Acting Neuromuscular Blockade Improves Inter-rater Reliability of Median Somatosensory Evoked Potentials in Post-cardiac arrest Prognostication

BACKGROUND

Although median nerve somatosensory evoked potentials are routinely used for prognostication in comatose cardiac arrest survivors, myogenic artifact can reduce inter-rater reliability, leading to unreliable or inaccurate results. To minimize this risk, we determined the benefit of neuromuscular blockade agents in improving the inter-rater reliability and signal-to-noise ratio of SSEPs in the context of prognostication.

METHODS

Thirty comatose survivors of cardiac arrest were enrolled in the study, following the request from an intensivist to complete an SSEP for prognostication. Right and left median nerve SSEPs were obtained from each patient, before and after administration of an NMB agent. Clinical histories and outcomes were retrospectively reviewed. The SSEP recordings before and after NMB were randomized and reviewed by five blinded raters, who assessed the latency and amplitude of cortical and noncortical potentials (vs. absence of response) as well as the diagnostic quality of cortical recordings. The inter-rater reliability of SSEP interpretation before and after NMB was compared via Fleiss' κ score.

RESULTS

Following NMB administration, Fleiss' κ score for cortical SSEP interpretation significantly improved from 0.37 to 0.60, corresponding to greater agreement among raters. The raters were also less likely to report the cortical recordings as nondiagnostic following NMB (40.7% nondiagnostic SSEPs pre-NMB; 17% post-NMB). The SNR significantly improved following NMB, especially when the pre-NMB SNR was low (< 10 dB). Across the raters, there were three patients whose SSEP interpretation changed from bilaterally absent to bilaterally present after NMB was administered (potential false positives without NMB).

CONCLUSIONS

NMB significantly improves the inter-rater reliability and SNR of median SSEPs for prognostication among comatose cardiac arrest survivors. To ensure the most reliable prognostic information in comatose post-cardiac arrest survivors, pharmacologic paralysis should be consistently used before recording SSEPs.

European Resuscitation Council and European Society of Intensive Care Medicine guidelines 2021: post-resuscitation care

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have collaborated to produce these post-resuscitation care guidelines for adults, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include the post-cardiac arrest syndrome, diagnosis of cause of cardiac arrest, control of oxygenation and ventilation, coronary reperfusion, haemodynamic monitoring and management, control of seizures, temperature control, general intensive care management, prognostication, long-term outcome, rehabilitation and organ donation.

European Resuscitation Council and European Society of Intensive Care Medicine Guidelines 2021: Post-resuscitation care

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have collaborated to produce these post-resuscitation care guidelines for adults, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include the post-cardiac arrest syndrome, diagnosis of cause of cardiac arrest, control of oxygenation and ventilation, coronary reperfusion, haemodynamic monitoring and management, control of seizures, temperature control, general intensive care management, prognostication, long-term outcome, rehabilitation, and organ donation.

Reliability in the assessment of paediatric somatosensory evoked potentials post cardiac arrest

OBJECTIVE

To measure inter- and intra-rater agreement in the interpretation of cortical somatosensory evoked potential (SSEP) components following paediatric cardiac arrest (CA) in multi-professional neurophysiology teams.

METHODS

Thirteen professionals blinded to patient outcome interpreted 96 SSEPs in paediatric patients 24-/48-/72-hours following CA. Of these, 34 were duplicates used to assess intra-rater agreement. Consistent interpretations (absent/present/indeterminate) between scientists (who record/identify SSEP components) and neurophysiologists (who provide prognostic SSEP interpretation) were expressed as percentages. Rates of agreement were calculated using Fleiss' kappa coefficient (K).

RESULTS

Unanimous agreement between professionals was present in 40% (95%CI: 28-54%) of the interpreted SSEPs, with a K value of 0.62 (95%CI: 0.55-0.70) based on average agreement. Agreement was similar between neurophysiologists (K = 0.67; 95%CI: 0.57-0.77) and scientists (K = 0.62; 95%CI: 0.54-0.70) but lower in patients < 2 years old (K = 0.23; 95%CI: 0.14-0.33) and in those with poor outcome (K = 0.21; 95%CI: 0.07-0.35). No SSEP was unanimously interpreted as absent and 92% (95%CI: 89-95%) of duplicate SSEPs were interpreted consistently.

CONCLUSION

Despite substantial agreement when interpreting prognostic SSEPs, this was significantly lower in children with poor outcome and of younger age.

SIGNIFICANCE

Clinicians using SSEPs in the intensive care unit should be aware of the inter-rater variability when interpreting SSEPs as absent.

Adult Advanced Life Support: 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations

This 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations for advanced life support includes updates on multiple advanced life support topics addressed with 3 different types of reviews. Topics were prioritized on the basis of both recent interest within the resuscitation community and the amount of new evidence available since any previous review. Systematic reviews addressed higher-priority topics, and included double-sequential defibrillation, intravenous versus intraosseous route for drug administration during cardiac arrest, point-of-care echocardiography for intra-arrest prognostication, cardiac arrest caused by pulmonary embolism, postresuscitation oxygenation and ventilation, prophylactic antibiotics after resuscitation, postresuscitation seizure prophylaxis and treatment, and neuroprognostication. New or updated treatment recommendations on these topics are presented. Scoping reviews were conducted for anticipatory charging and monitoring of physiological parameters during cardiopulmonary resuscitation. Topics for which systematic reviews and new Consensuses on Science With Treatment Recommendations were completed since 2015 are also summarized here. All remaining topics reviewed were addressed with evidence updates to identify any new evidence and to help determine which topics should be the highest priority for systematic reviews in the next 1 to 2 years.

Adult Advanced Life Support: 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

This 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations for advanced life support includes updates on multiple advanced life support topics addressed with 3 different types of reviews. Topics were prioritized on the basis of both recent interest within the resuscitation community and the amount of new evidence available since any previous review. Systematic reviews addressed higher-priority topics, and included double-sequential defibrillation, intravenous versus intraosseous route for drug administration during cardiac arrest, point-of-care echocardiography for intra-arrest prognostication, cardiac arrest caused by pulmonary embolism, postresuscitation oxygenation and ventilation, prophylactic antibiotics after resuscitation, postresuscitation seizure prophylaxis and treatment, and neuroprognostication. New or updated treatment recommendations on these topics are presented. Scoping reviews were conducted for anticipatory charging and monitoring of physiological parameters during cardiopulmonary resuscitation. Topics for which systematic reviews and new Consensuses on Science With Treatment Recommendations were completed since 2015 are also summarized here. All remaining topics reviewed were addressed with evidence updates to identify any new evidence and to help determine which topics should be the highest priority for systematic reviews in the next 1 to 2 years.

Prediction of poor neurological outcome in comatose survivors of cardiac arrest: a systematic review

Purpose

To assess the ability of clinical examination, blood biomarkers, electrophysiology, or neuroimaging assessed within 7 days from return of spontaneous circulation (ROSC) to predict poor neurological outcome, defined as death, vegetative state, or severe disability (CPC 3–5) at hospital discharge/1 month or later, in comatose adult survivors from cardiac arrest (CA).

Methods

PubMed, EMBASE, Web of Science, and the Cochrane Database of Systematic Reviews (January 2013–April 2020) were searched. Sensitivity and false-positive rate (FPR) for each predictor were calculated. Due to heterogeneities in recording times, predictor thresholds, and definition of some predictors, meta-analysis was not performed.

Results

Ninety-four studies (30,200 patients) were included. Bilaterally absent pupillary or corneal reflexes after day 4 from ROSC, high blood values of neuron-specific enolase from 24 h after ROSC, absent N20 waves of short-latency somatosensory-evoked potentials (SSEPs) or unequivocal seizures on electroencephalogram (EEG) from the day of ROSC, EEG background suppression or burst-suppression from 24 h after ROSC, diffuse cerebral oedema on brain CT from 2 h after ROSC, or reduced diffusion on brain MRI at 2–5 days after ROSC had 0% FPR for poor outcome in most studies. Risk of bias assessed using the QUIPS tool was high for all predictors.

Conclusion

In comatose resuscitated patients, clinical, biochemical, neurophysiological, and radiological tests have a potential to predict poor neurological outcome with no false-positive predictions within the first week after CA. Guidelines should consider the methodological concerns and limited sensitivity for individual modalities. (PROSPERO CRD42019141169)

Electronic supplementary material

The online version of this article (10.1007/s00134-020-06198-w) contains supplementary material, which is available to authorized users.

Beyond dichotomy: patterns and amplitudes of SSEPs and neurological outcomes after cardiac arrest

Background

We hypothesized that the absence of P25 and the N20–P25 amplitude in somatosensory evoked potentials (SSEPs) have higher sensitivity than the absence of N20 for poor neurological outcomes, and we evaluated the ability of SSEPs to predict long-term outcomes using pattern and amplitude analyses.

Methods

Using prospectively collected therapeutic hypothermia registry data, we evaluated whether cortical SSEPs contained a negative or positive short-latency wave (N20 or P25). The N20–P25 amplitude was defined as the largest difference in amplitude between the N20 and P25 peaks. A good or poor outcome was defined as a Glasgow-Pittsburgh Cerebral Performance Category (CPC) score of 1–2 or 3–5, respectively, 6 months after cardiac arrest.

Results

A total of 192 SSEP recordings were included. In all patients with a good outcome (n = 51), both N20 and P25 were present. Compared to the absence of N20, the absence of N20–P25 component improved the sensitivity for predicting a poor outcome from 30.5% (95% confidence interval [CI], 23.0–38.8%) to 71.6% (95% CI, 63.4–78.9%), while maintaining a specificity of 100% (93.0–100.0%). Using an amplitude < 0.64 μV, i.e., the lowest N20–P25 amplitude in the good outcome group, as the threshold, the sensitivity for predicting a poor neurological outcome was 74.5% (95% CI, 66.5–81.4%). Using the highest N20–P25 amplitude in the CPC 4 group (2.31 μV) as the threshold for predicting a good outcome, the sensitivity and specificity were 52.9% (95% CI, 38.5–67.1%) and 96.5% (95% CI, 91.9–98.8%), respectively. The predictive performance of the N20–P25 amplitude was good, with an area under the receiver operating characteristic curve (AUC) of 0.94 (95% CI, 0.90–0.97). The absence of N20 was statistically inferior regarding outcome prediction (p < 0.05), and amplitude analysis yielded significantly higher AUC values than did the pattern analysis (p < 0.05).

Conclusions

The simple pattern analysis of whether the N20–P25 component was present had a sensitivity comparable to that of the N20–P25 amplitude for predicting a poor outcome. Amplitude analysis was also capable of predicting a good outcome.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2510-x) contains supplementary material, which is available to authorized users.