Mismatch negativity to predict subsequent awakening in deeply sedated critically ill patients

BACKGROUND

Mismatch negativity (MMN) is the neurophysiological correlate of cognitive integration of novel stimuli. Although MMN is a well-established predictor of awakening in non-sedated comatose patients, its prognostic value in deeply sedated critically ill patients remains unknown. The aim of this prospective, observational pilot study was to investigate the prognostic value of MMN for subsequent awakening in deeply sedated critically ill patients.

METHODS

MMN was recorded in 43 deeply sedated critically ill patients on Day 3 of ICU admission using a classical 'odd-ball' paradigm that delivers rare deviant sounds in a train of frequent standard sounds. Individual visual analyses and a group level analysis of recordings were performed. MMN amplitudes were then analysed according to the neurological status (awake vs not awake) at Day 28.

RESULTS

Median (inter-quartile range) Richmond Assessment Sedation Scale (RASS) at the time of recording was -5 (range, from -5 to -4.5). Visual detection of MMN revealed a poor inter-rater agreement [kappa=0.17, 95% confidence interval (0.07-0.26)]. On Day 28, 30 (70%) patients had regained consciousness while 13 (30%) had not. Quantitative group level analysis revealed a significantly greater MMN amplitude for patients who awakened compared with those who had not [mean (standard deviation) = -0.65 (1.4) vs 0.08 (0.17) μV, respectively; P=0.003).

CONCLUSIONS

MMN can be observed in deeply sedated critically ill patients and could help predict subsequent awakening. However, visual analysis alone is unreliable and should be systematically completed with individual level statistics.

Early impairment of intracranial conduction time predicts mortality in deeply sedated critically ill patients: a prospective observational pilot study

Background

Somatosensory (SSEP) and brainstem auditory (BAEP) evoked potentials are neurophysiological tools which, respectively, explore the intracranial conduction time (ICCT) and the intrapontine conduction time (IPCT). The prognostic values of prolonged cerebral conduction times in deeply sedated patients have never been assessed. Sedated patients are at risk of developing new neurological complications, undetected. In this prospective observational bi-center pilot study, we investigated whether early impairment of SSEP’s ICCT and/or BAEP’s IPCT could predict in-ICU mortality or altered mental status (AMS), in deeply sedated critically ill patients.

Methods

SSEP by stimulation of the median nerve and BAEP were assessed in critically ill patients receiving deep sedation on day 3 following ICU admission. Deep sedation was defined by a Richmond Assessment sedation Scale (RASS) <−3. Mean left- and right-side ICCT and IPCT were measured for each patient. Primary and secondary outcomes were, respectively, in-ICU mortality and AMS defined as the occurrence of delirium and/or delayed awakening after discontinuation of sedation.

Results

Eighty-six patients were studied of which 49 (57%) were non-brain-injured and 37 (43%) were brain-injured. Impaired ICCT was a predictor of in-ICU mortality after adjustment on the global Sequential Organ Failure Assessment score (SOFA) [OR (95% CI) = 2.69 (1.05–6.85); p = 0.039] and on the non-neurological SOFA components [2.67 (1.05–6.81); p = 0.040]. IPCT was more frequently delayed in the subgroup of patients who developed post-sedation AMS (24%) compared those without AMS (0%). However, this difference did not reach statistical significance (p = 0.053). Impairment rates of ICCT and IPCT were not found to be significantly different between non-brain- and brain-injured subgroups of patients.

Conclusion

In critically ill patients receiving deep sedation, early ICCT impairment was associated with mortality. Somatosensory and brainstem auditory evoked potentials may be useful early warning indicators of brain dysfunction as well as prognostic markers in deeply sedated critically ill patients.

Brainstem response patterns in deeply-sedated critically-ill patients predict 28-day mortality

Background and purpose

Deep sedation is associated with acute brain dysfunction and increased mortality. We had previously shown that early-assessed brainstem reflexes may predict outcome in deeply sedated patients. The primary objective was to determine whether patterns of brainstem reflexes might predict mortality in deeply sedated patients. The secondary objective was to generate a score predicting mortality in these patients.

Methods

Observational prospective multicenter cohort study of 148 non-brain injured deeply sedated patients, defined by a Richmond Assessment sedation Scale (RASS) <-3. Brainstem reflexes and Glasgow Coma Scale were assessed within 24 hours of sedation and categorized using latent class analysis. The Full Outline Of Unresponsiveness score (FOUR) was also assessed. Primary outcome measure was 28-day mortality. A “Brainstem Responses Assessment Sedation Score” (BRASS) was generated.

Results

Two distinct sub-phenotypes referred as homogeneous and heterogeneous brainstem reactivity were identified (accounting for respectively 54.6% and 45.4% of patients). Homogeneous brainstem reactivity was characterized by preserved reactivity to nociceptive stimuli and a partial and topographically homogenous depression of brainstem reflexes. Heterogeneous brainstem reactivity was characterized by a loss of reactivity to nociceptive stimuli associated with heterogeneous brainstem reflexes depression. Heterogeneous sub-phenotype was a predictor of increased risk of 28-day mortality after adjustment to Simplified Acute Physiology Score-II (SAPS-II) and RASS (Odds Ratio [95% confidence interval] = 6.44 [2.63–15.8]; p<0.0001) or Sequential Organ Failure Assessment (SOFA) and RASS (OR [95%CI] = 5.02 [2.01–12.5]; p = 0.0005). The BRASS (and marginally the FOUR) predicted 28-day mortality (c-index [95%CI] = 0.69 [0.54–0.84] and 0.65 [0.49–0.80] respectively).

Conclusion

In this prospective cohort study, around half of all deeply sedated critically ill patients displayed an early particular neurological sub-phenotype predicting 28-day mortality, which may reflect a dysfunction of the brainstem.

[Starvation ketosis in a breastfeeding woman]

INTRODUCTION

Bovine ketosis is a rare cause of metabolic acidosis. It is a starvation ketosis that appears in lactating woman.

CASE REPORT

A 29-year-old woman had a previous gastric surgery one month ago while breastfeeding her 6-month child. She presented to emergency with dyspnea, fatigue, weight loss and anorexia. The explorations revealed a serious metabolic acidosis with a high anion gap, for which all other causes have been eliminated.

CONCLUSION

A restrictive diet in lactating patients is a major risk of ketosis or bovine ketosis. Medico-surgical treatment of obesity during lactation seems unreasonable. Breastfeeding should be systematically sought before a medical and surgical management of obesity. With the spread of bariatric surgery, starvation ketosis is a cause of metabolic acidosis not to ignore.

[Impact of anaesthesia management on post-surgical ventilation in post-anaesthesia care unit]

INTRODUCTION

Control of residual muscle paralysis and hypothermia reduce postoperative complications rate. Short context sensitive half life anaesthetic agents allow a better adjustment of anaesthesia depth according to surgical requirement and a safe early extubation. Using a large clinical database, impact of these three strategies was assessed on clinical criteria such as use of neostigmine in postanaesthesia care unit (PACU), temperature, sedation score at the arrival into PACU and mechanical ventilation weaning.

METHODS

This is a retrospective study on two separated periods. Since 2001, clinical events are entered into the database during and after anaesthesia in the same file. Agreement of anaesthesia staff to these strategies was assessed by the proportion of patients receiving modern anaesthetic agents (desflurane, sevoflurane and remifentanil) and the use of warming devices. Clinical impact was assessed by the number of patients receiving neostigmine in PACU, sedation score and temperature at the arrival in PACU and number of patients with mechanical ventilation in PACU.

RESULTS

Between the two periods (12,033 and 11,805 patients, respectively), use of sevoflurane, desflurane and remifentanil markedly increased, as well as the use of warming devices. Number of patients with neuromuscular reversal in PACU decreased from 73 to 11 and sedation score improved dramatically. Incidence of postoperative ventilation in PACU decreased from 1.1% (n=132) to 0.2% (n=30). Incidence of postoperative hypothermia was not changed during the two periods but incidence of hypothermia in the mechanically ventilated patient increased from 34.1 to 46.6%. Length of stay in PACU decreased from 122 to 114 minutes (p<0.05).

DISCUSSION

Implementation of new intraoperative protocols induced major effects on postoperative clinical parameters and especially postoperative mechanical ventilation. Failure of our hypothermia prevention associated with a fast return of consciousness lead to wean from mechanical ventilation hypothermic patients. Risks of this strategy were not estimated.

Glucocorticoids and sepsis

Although systemic inflammation is the hallmark of sepsis, the use of glucocorticoids remained controversial during many years. Gluco-corticoids exert key actions during sepsis, interacting with metabolism, immune and cardiovascular systems. Glucocorticoid insufficiency is common during sepsis and may result from insufficient production of cortisol or peripheral tissues resistance. Thus, recent randomised trials showed that a replacement therapy with long course of low dose corticosteroids reduced mortality from septic shock. Improvement in survival may result from reduced duration of shock, alleviation of the systemic inflammatory response, and reduction in the number and intensity of organs dysfunction. This article summarises why, when and how glucocorticoids should be used in the management of septic shock.