Tracking auditory mismatch negativity responses during full conscious state and coma

The mismatch negativity (MMN) is considered the electrophysiological change-detection response of the brain, and therefore a valuable clinical tool for monitoring functional changes associated with return to consciousness after severe brain injury. Using an auditory multi-deviant oddball paradigm, we tracked auditory MMN responses in seventeen healthy controls over a 12-h period, and in three comatose patients assessed over 24 h at two time points. We investigated whether the MMN responses show fluctuations in detectability over time in full conscious awareness, or whether such fluctuations are rather a feature of coma. Three methods of analysis were utilized to determine whether the MMN and subsequent event-related potential (ERP) components could be identified: traditional visual analysis, permutation t-test, and Bayesian analysis. The results showed that the MMN responses elicited to the duration deviant-stimuli are elicited and reliably detected over the course of several hours in healthy controls, at both group and single-subject levels. Preliminary findings in three comatose patients provide further evidence that the MMN is often present in coma, varying within a single patient from easily detectable to undetectable at different times. This highlights the fact that regular and repeated assessments are extremely important when using MMN as a neurophysiological predictor of coma emergence.

Diarrhea during critical illness: a multicenter cohort study

PURPOSE

To study the incidence, predictors, and outcomes of diarrhea during the stay in the intensive care unit (ICU).

METHODS

Prospective cohort of consecutive adults in the ICU for > 24 h during a 10-week period across 12 intensive care units (ICUs) internationally. The explored outcomes were: (1) incidence of diarrhea, (2) Clostridioides difficile-associated diarrhea (CDAD); (3) ICU and hospital length of stay (LOS) and mortality in patients with diarrhea. We fit generalized linear models to evaluate the predictors, management, morbidity and mortality associated with diarrhea.

RESULTS

Among 1109 patients aged 61.4 (17.5) [mean (standard deviation)] years, 981(88.5%) were medical and 645 (58.2%) were mechanically ventilated. The incidence was 73.8% (818 patients, 73.8%, 95% confidence interval [CI] 71.1-76.6) using the definition of the World Health Organisation (WHO). Incidence varied across definitions (Bristol 53.5%, 95% CI 50.4-56.7; Bliss 37.7%, 95% CI 34.9-40.4). Of 99 patients with diarrhea undergoing CDAD testing, 23 tested positive (2.2% incidence, 95% CI 1.5-3.4). Independent predictors included enteral nutrition (RR 1.23, 95% CI 1.16-1.31, p < 0.001), antibiotic days (RR 1.02, 95% CI 1.02-1.03, p < 0.001), and suppositories (RR 1.14 95% CI 1.06-1.22, p < 0.001). Opiates decreased diarrhea risk (RR 0.76, 95% CI 0.68-0.86, p < 0.001). Diarrhea prompted management modifications (altered enteral nutrition or medications: RR 10.25, 95% CI 5.14-20.45, p < 0.001) or other consequences (fecal management device or CDAD testing: RR 6.16, 95% CI 3.4-11.17, p < 0.001). Diarrhea was associated with a longer time to discharge for ICU or hospital stay, but was not associated with hospital mortality.

CONCLUSION

Diarrhea is common, has several predictors, and prompts changes in patient care, is associated with longer time to discharge but not mortality.

Development of a point of care system for automated coma prognosis: a prospective cohort study protocol

INTRODUCTION

Coma is a deep state of unconsciousness that can be caused by a variety of clinical conditions. Traditional tests for coma outcome prediction are based mainly on a set of clinical observations. Recently, certain event-related potentials (ERPs), which are transient electroencephalogram (EEG) responses to auditory, visual or tactile stimuli, have been introduced as useful predictors of a positive coma outcome (ie, emergence). However, such tests require the skills of clinical neurophysiologists, who are not commonly available in many clinical settings. Additionally, none of the current standard clinical approaches have sufficient predictive accuracies to provide definitive prognoses.

OBJECTIVE

The objective of this study is to develop improved machine learning procedures based on EEG/ERP for determining emergence from coma.

METHODS AND ANALYSIS

Data will be collected from 50 participants in coma. EEG/ERP data will be recorded for 24 consecutive hours at a maximum of five time points spanning 30 days from the date of recruitment to track participants' progression. The study employs paradigms designed to elicit brainstem potentials, middle-latency responses, N100, mismatch negativity, P300 and N400. In the case of patient emergence, data are recorded on that occasion to form an additional basis for comparison. A relevant data set will be developed from the testing of 20 healthy controls, each spanning a 15-hour recording period in order to formulate a baseline. Collected data will be used to develop an automated procedure for analysis and detection of various ERP components that are salient to prognosis. Salient features extracted from the ERP and resting-state EEG will be identified and combined to give an accurate indicator of prognosis.

ETHICS AND DISSEMINATION

This study is approved by the Hamilton Integrated Research Ethics Board (project number 4840). Results will be disseminated through peer-reviewed journal articles and presentations at scientific conferences.

TRIAL REGISTRATION NUMBER

NCT03826407.

Diarrhoea: interventions, consequences and epidemiology in the intensive care unit (DICE-ICU): a protocol for a prospective multicentre cohort study

INTRODUCTION

Diarrhoea is a frequent concern in the intensive care unit (ICU) and is associated with prolonged mechanical ventilation, increased length of ICU stay, skin breakdown and renal dysfunction. However, its prevalence, aetiology and prognosis in the critically ill have been poorly studied. The primary objectives of this study are to determine the incidence, risk factors and consequences of diarrhoea in critically ill adults. The secondary objectives are to estimate the incidence of Clostridium difficile-associated diarrhoea (CDAD) in ICU patients and to validate the Bristol Stool Chart and Bliss Stool Classification System characterising bowel movements in the ICU. Our primary outcome is the incidence of diarrhoea . Our secondary outcomes include: CDAD, ICU and hospital mortality and ICU and hospital length of stay.

METHODS AND ANALYSIS

This international prospective cohort study will enrol patients over 10 weeks in 12 ICUs in Canada, the USA, Poland and Saudi Arabia. We will include all patients 18 years of age and older who are admitted to the ICU for at least 24 hours and follow them daily until ICU discharge. Our primary outcome is the incidence of diarrhoea based on the WHO definition, during the ICU stay. Our secondary outcomes include: CDAD, ICU and hospital mortality and ICU and hospital length of stay. We will use logistic regression to identify factors associated with diarrhoea (as defined using WHO criteria) and the kappa statistic to measure agreement on diarrhoea rates between the WHO definition and the Bristol Stool Chart and Bliss Stool Classification System.

ETHICS AND DISSEMINATION

The protocol has been approved by the research ethics board of all participating centres. The diarrhoea interventions, consequences and epidemiology in the intensive care unit (DICE-ICU) study will generate evidence about diarrhoea and its frequency, predisposing factors and consequences, to inform critical care practice and future research.

LAY SUMMARY

Diarrhoea is a frequent clinical problem for hospitalised patients including those who are critically ill in the ICU. Diarrhoea can cause complications such as skin damage, dehydration and kidney problems. It is not clear how common diarrhoea is in the ICU, the factors that cause it or the best way for clinicians to assess it. The DICE-ICU study is an international prospective observational study to examine the frequency, risk factors and outcomes of diarrhoea during critical illness.

Furosemide and Albumin for Diuresis of Edema (FADE): A parallel-group, blinded, pilot randomized controlled trial

PURPOSE

To assess the feasibility of a trial evaluating whether hyperoncotic albumin, in addition to diuretics, improves diuresis and facilitates liberation from mechanical ventilation in critically ill adults.

MATERIALS AND METHODS

We randomized 46 hemodynamically stable patients with hypoalbuminemia, prescribed diuretics by treating clinicians, to receive 100 mL of 25% albumin or 0.9% saline placebo BID, for three days, in blinded fashion. We chose five feasibility measurements: enrolment of 50% of eligible patients, at least one patient/week; administration of study treatment within 2 h of diuretics in 85% of patients; completion of study regimen in 80% of patients; and avoidance of open label albumin in 85% of patients. Clinical outcomes included fluid balance, ventilator-free days, and mortality.

RESULTS

We randomized 85% of eligible patients. Eighty-four percent received study treatment within 2 h of diuretics, 69% received all doses of study treatment. Study treatment was held in the albumin and placebo groups because of no further need for diuresis (4 vs. 1), hypotension (2 v. 4), and albumin > 35 (1 v. 0). Twenty percent of patients received open-label albumin. Clinical outcomes were similar between groups.

CONCLUSIONS

The current study design did not demonstrate feasibility, but can inform the design of a definitive trial.

Furosemide and albumin for diuresis of edema (FADE): a study protocol for a randomized controlled trial

Background

Fluid retention is a common complication of critical illness. It typically results from large-volume fluid infusions during acute resuscitation and is worsened by hypoalbuminemia. Recognized as edema, fluid retention is important for its association with delayed weaning and increased mortality. The standard treatment is the administration of diuretics, with or without albumin. We hypothesize that intravenous 25% albumin plus furosemide, by comparison with furosemide alone, improves diuresis, oxygenation, and hemodynamic stability in the deresuscitation of critically ill, hypoalbuminemic patients. We propose a pilot study to determine the feasibility of a trial to investigate this hypothesis.

Methods/Design

FADE is a single-center, parallel, pilot randomized controlled trial. We aim to allocate 50 hemodynamically stable, hypoalbuminemic adult patients receiving diuresis to treatment with either 100 ml of either 25% albumin or normal saline placebo twice daily, for a total of six doses. Diuretics are to be prescribed by the caregiving team at least twice daily, and administered within 2 hours following study treatment. Patients, intensive care unit (ICU) clinicians, data collectors, and outcome adjudicators will be blinded to treatment allocation. Feasibility outcome measures include the proportion of patients receiving albumin within 2 hours of diuretic, the proportion of patients receiving the full six doses of study treatment, the proportion of patients who receive open label 25% albumin, and the rate of recruitment. Physiologic, laboratory, and clinical data are collected until discharge from the ICU or until 30 days.

Discussion

This is the first randomized trial to assess the use of hyperoncotic albumin in addition to diuretics in a general ICU population. Should this pilot study demonstrate feasibility, the primary outcome measure of the larger clinical trial will be the number of ventilator-free days, with secondary clinical outcome measures of duration of mechanical ventilation, length of ICU stay, episodes of hemodynamic instability and mortality. The addition of 25% albumin to standard diuretic therapy is a promising treatment in the post-resuscitation care of the critically ill patient.

Trial registration

ClinicalTrials.gov NCT02055872; ISRCTN70191881.

Prescribed targets for titration of vasopressors in septic shock: a retrospective cohort study

BACKGROUND

Without robust clinical evidence to guide titration of vasopressors in septic shock, it is unclear how dosing of these potent medications occurs. We sought to measure the proportion of vasopressor prescriptions for septic shock that were missing explicit targets and to describe the targets that we identified.

METHODS

We conducted a multicentre, retrospective cohort study involving 9 intensive care units (ICUs) located at 3 academic hospitals in Canada and Australia. We reviewed charts of consecutive patients aged 18 years or older who were admitted to the ICU for a presumptive diagnosis of sepsis. Other inclusion criteria were hypotension (systolic arterial pressure ≤ 90 mm Hg or mean arterial pressure [MAP] ≤ 65 mm Hg) and continuous infusion of vasopressors for at least 1 hour within the initial 48 hours of ICU stay, the period of observation for this study.

RESULTS

We included data from 369 patient charts. At least 1 target was specified in 99% of charts. The most common targets were MAP measurements (73%). The median initial MAP target was 65 (range 55-90) mm Hg. In multivariable regression models, hospital site and older age of the patient, but not comorbidities of the patient, were associated with MAP targets. In 40% of patients, the treating team modified the initial target at least once.

INTERPRETATION

This study suggests that an explicit blood pressure target accompanies nearly every vasopressor prescription and that patient characteristics have little influence on its value. Identification of a titration strategy that will maximize benefit and minimize harm constitutes a research priority.

A retrospective cohort pilot study to evaluate a triage tool for use in a pandemic

Introduction

The objective of this pilot study was to assess the usability of the draft Ontario triage protocol, to estimate its potential impact on patient outcomes, and ability to increase resource availability based on a retrospective cohort of critically ill patients cared for during a non-pandemic period.

Methods

Triage officers applied the protocol prospectively to 2 retrospective cohorts of patients admitted to 2 academic medical/surgical ICUs during an 8 week period of peak occupancy. Each patient was assigned a treatment priority (red -- 'highest', yellow -- 'intermediate', green -- 'discharge to ward', or blue/black -- 'expectant') by the triage officers at 3 separate time points (at the time of admission to the ICU, 48, and 120 hours post admission).

Results

Overall, triage officers were either confident or very confident in 68.4% of their scores; arbitration was required in 54.9% of cases. Application of the triage protocol would potentially decrease the number of required ventilator days by 49.3% (568 days) and decrease the total ICU days by 52.6% (895 days). On the triage protocol at ICU admission the survival rate in the red (93.7%) and yellow (62.5%) categories were significantly higher then that of the blue category (24.6%) with associated P values of < 0.0001 and 0.0003 respectively. Further, the survival rate of the red group was significantly higher than the overall survival rate of 70.9% observed in the cohort (P < 0.0001). At 48 and 120 hours, survival rates in the blue group increased but remained lower then the red or yellow groups.

Conclusions

Refinement of the triage protocol and implementation is required prior to future study, including improved training of triage officers, and protocol modification to minimize the exclusion from critical care of patients who may in fact benefit. However, our results suggest that the triage protocol can help to direct resources to patients who are most likely to benefit, and help to decrease the demands on critical care resources, thereby making available more resources to treat other critically ill patients.

Glycemic control in the ICU: a multicenter survey

BACKGROUND

Intensive insulin therapy has recently been shown to decrease morbidity and mortality in the critically ill population in a large randomized clinical trial.

OBJECTIVE

To determine the beliefs and attitudes of ICU clinicians about glycemic control.

DESIGN

Self-administered survey.

PARTICIPANTS

ICU nurses and physicians in five university-affiliated multidisciplinary ICUs.

RESULTS

A total of 317 questionnaires were returned from 233 ICU nurses and 84 physicians. The reported clinically important threshold for hypoglycemia was 4 mmol/l (median, IQR 3-4 mmol/l). In non-diabetic patients, the clinically important threshold for hyperglycemia was 10 mmol/l (IQR 9-12 mmol/l); however, nurses had a significantly higher threshold than physicians (difference of 0.52 mmol/l (95% CI 0.09-0.94 mmol/l, P=0.018). In diabetic patients, the clinically important threshold for hyperglycemia was also 10 mmol/l (IQR 10-12 mmol/l), and again nurses had a significantly higher threshold than physicians (0.81 mmol/l, 95% CI 0.29-1.32 mmol/l, P=0.0023). Avoidance of hyperglycemia was judged most important for diabetic patients (87.7%, 95% CI 84.1-91.3%), patients with acute brain injury (84.5%, 95% CI 80.5-88.5%), patients with a recent seizure (74.4%, 95% CI 69.6-79.3%), patients with advanced liver disease (64.0%, 95% CI 58.7-69.3%), and for patients with acute myocardial infarction (64.0%, 95% CI 58.7-69.3%). Physicians expressed more concern than nurses about avoiding hyperglycemia in patients with acute myocardial infarction ( P=0.0004). ICU clinicians raised concerns about the accuracy of glucometer measurements in critically ill patients (46.1%, 95% CI 40.5-51.6%).

CONCLUSIONS

Attention to these beliefs and attitudes could enhance the success of future clinical, educational and research efforts to modify clinician behavior and achieve better glycemic control in the ICU setting.

Influence of perceived functional and employment status on cardiopulmonary resuscitation directives

BACKGROUND

Perceptions about functional and employment status before admission to the intensive care unit (ICU) may influence how patients and clinicians make decisions about cardiopulmonary resuscitation.

OBJECTIVE

To examine the relationship between cardiopulmonary resuscitation directives established within 24 hours of admission to the ICU and clinical perceptions of premorbid functional and employment status.

DESIGN

Prospective observational study in 15 university-affiliated centers in Canada, the United States, Australia, and Sweden.

PATIENTS

A total of 1,008 ICU patients aged 18 years or older expected to stay in the ICU at least 72 hours.

MEASUREMENTS

By using multinomial logistic regression, we examined the relationship between functional status and employment status perceived by the ICU team 1 month before ICU admission (the independent variables) and resuscitation status (the dependent variable). Each patient had either an explicit resuscitation directive (to resuscitate or not to resuscitate), or an implicit resuscitation directive to resuscitate.

RESULTS

On average, patients were 61.7 years (+/-17.4 y) old with an Acute Physiology and Chronic Health Evaluation (APACHE) II score of 21.5 (+/-8.7); 846 (83.9%) were ventilated mechanically within 48 hours and 345 (34.2%) died in the ICU. Most patients (793, 78.7%) had no explicit resuscitation directive; 98 (9.7%) had an explicit plan to resuscitate, whereas 117 (11.6%) had an explicit plan of do-not-resuscitate. Of 1,008 patients, 98 (9.7%) were severely functionally limited, 217 (21.5%) were somewhat limited, 628 (62.3%) were totally independent, and 65 (6.4%) had unknown functional status 1 month before ICU admission. Severe functional status impairment was associated moderately with an explicit plan to resuscitate (odds ratio, 2.2 relative to no explicit directive) and associated strongly with an explicit do-not-resuscitate plan (odds ratio, 6.2 relative to no explicit directive, P value on the difference =.011). This relationship was not influenced by age, sex, APACHE II score, medical or surgical status, admission diagnosis, employment status, or city. However, severe functional status was associated strongly and significantly with an explicit do-not-resuscitate directive among those who could not participate in decision making (odds ratio, 8.2; 95% confidence interval, 4.5-15.0), and more weakly associated in those who could participate (odds ratio, 1.7; 95% confidence interval, 0.3-8.6). Being unemployed was associated with an increased odds of an explicit resuscitation directive versus no explicit directive (odds ratio, 5.5; 95% confidence interval, 2.2-13.4).

CONCLUSIONS

Functional status impairment perceived by the ICU team is associated clearly with do-not-resuscitate directives in patients unable to participate in decision making. However, the association appears much weaker in patients able to participate in decision making. PATIENTS' perceived employment status also may influence resuscitation decisions. Our results emphasize the challenges of ensuring that crucial resuscitation decisions are not affected adversely by patients' inability to participate in decisions, and by their functional and employment status.

Withdrawal of mechanical ventilation in anticipation of death in the intensive care unit

BACKGROUND

In critically ill patients who are receiving mechanical ventilation, the factors associated with physicians' decisions to withdraw ventilation in anticipation of death are unclear. The objective of this study was to examine the clinical determinants that were associated with the withdrawal of mechanical ventilation.

METHODS

We studied adults who were receiving mechanical ventilation in 15 intensive care units, recording base-line physiological characteristics, daily Multiple Organ Dysfunction Scores, the patient's decision-making ability, the type of life support administered, the use of do-not-resuscitate orders, the physician's prediction of the patient's status, and the physician's perceptions of the patient's preferences about the use of life support. We examined the relation between these factors and withdrawal of mechanical ventilation, using Cox proportional-hazards regression analysis.

RESULTS

Of 851 patients who were receiving mechanical ventilation, 539 (63.3 percent) were successfully weaned, 146 (17.2 percent) died while receiving mechanical ventilation, and 166 (19.5 percent) had mechanical ventilation withdrawn. The need for inotropes or vasopressors was associated with withdrawal of the ventilator (hazard ratio, 1.78; 95 percent confidence interval, 1.20 to 2.66; P=0.004), as were the physician's prediction that the patient's likelihood of survival in the intensive care unit was less than 10 percent (hazard ratio, 3.49; 95 percent confidence interval, 1.39 to 8.79; P=0.002), the physician's prediction that future cognitive function would be severely impaired (hazard ratio, 2.51; 95 percent confidence interval, 1.28 to 4.94; P=0.04), and the physician's perception that the patient did not want life support used (hazard ratio, 4.19; 95 percent confidence interval, 2.57 to 6.81; P<0.001).

CONCLUSIONS

Rather than age or the severity of the illness and organ dysfunction, the strongest determinants of the withdrawal of ventilation in critically ill patients were the physician's perception that the patient preferred not to use life support, the physician's predictions of a low likelihood of survival in the intensive care unit and a high likelihood of poor cognitive function, and the use of inotropes or vasopressors.

Use of a rapid arterial blood gas analyzer to estimate blood hemoglobin concentration among critically ill adults

OBJECTIVE

To evaluate whether measurement of the hemoglobin (Hb) concentration with a blood gas analyzer approximates that determined by a conventional coulter counter in critically ill adults.

DESIGN

Prospective patient series.

SETTING

A 32-bed cardiovascular, neurosurgical, trauma and medical-surgical intensive care unit in a single Canadian center.

PATIENTS

We consecutively recruited 202 critically ill adults, the majority of whom had recent cardiac or vascular surgery, neurosurgery or trauma.

MEASUREMENTS

The nurse obtained a single arterial blood sample within a few hours of the patient's admission to the intensive care unit. The Hb concentration was determined from each blood sample in a masked fashion, using both a blood gas analyzer and a conventional laboratory coulter counter.

MAIN RESULTS

A total of 202 consecutive paired analyses were conducted. There was a highly significant correlation between the coulter counter and blood gas analyzer methods of Hb measurement (r2 = 0.98, 95% confidence interval [CI] = 0.97-0.99; P < 0.0001). Using the method of Bland and Altman, the overall mean difference in Hb concentration between the coulter counter and the blood gas analyzer was -4.3 g/l (95% CI = -11.0 to 2.4). Of the 11 (5.4%) Hb measurements that extended beyond the upper and lower 95% CI, 10 (5.0%) were within +/- 3 g/l of these confidence limits.

CONCLUSIONS

An arterial blood gas analyzer may provide a valid alternative method to the traditional coulter counter for the rapid assessment of Hb concentration among critically ill adults. Since issues related to its safety, quality control, data entry and cost savings have yet to be addressed, however, use of such point of care testing should be viewed as a supplement to conventional laboratory testing.

Pilot study of the accuracy of bedside glucometry in the intensive care unit

OBJECTIVE

To evaluate the accuracy of bedside glucometry among critically ill patients.

DESIGN

Prospective audit, with sequential specimen collection.

SETTING

Thirty-two-bed cardiovascular, neurosurgical, and medical-surgical intensive care unit in a single Canadian center.

PATIENTS

Ten critically ill adults, who were sequentially followed during their intensive care unit stay. Eight had diabetes mellitus, and three were in shock.

MEASUREMENTS AND MAIN RESULTS

Repeat arterial blood samples were obtained by the attending nurse, who withdrew a portion of the sample and performed reflectance glucometry at the bedside. The remainder was immediately sent in a vacuum-sealed plasma separation tube to the hospital laboratory, and analyzed using a conventional plasma glucose analyzer by a laboratory technologist. Sequential samples were taken at intervals of at least 12 hrs of one other. A total of 105 arterial glucose pairs were obtained. There was a significant correlation between the laboratory and glucometry determined glucose concentrations (intraclass correlation coefficient = 0.86, p <.0001). The overall average laboratory-glucometry glucose difference was -0.04 mmol/L (95% confidence interval [CI] -2.3-2.2 mmol/L). Five out of 105 values (4.8%) lay beyond these confidence bounds. The square of the Pearson correlation coefficient (r(2)) between the mean glucose level and the laboratory-glucometry glucose difference was not significant (0.01, 95% CI 0.005-0.04; p =.22), suggesting the absence of any trend between rising glucose concentration and the laboratory-glucometry difference.

CONCLUSIONS

Bedside glucose testing of arterial whole blood samples may be an accurate alternative to laboratory plasma glucose measurement among critically ill adults, within approximately 2.3 mmol/L of certainty. Because previous studies have suggested that this bedside technique may be prone to a moderate degree of error among patients in shock as well as those with an abnormal blood pH or hematocrit, larger studies are needed to confirm our findings.