Association of the Bedside Shivering Assessment Scale and derived EMG power during therapeutic hypothermia in survivors of cardiac arrest

Effect of Prewarming on Postoperative Hypothermia, Vital Signs, and Thermal Comfort: A Randomized Controlled Trial

This study aimed to determine the effects of preoperative active and passive warming on postoperative hypothermia, vital signs, and perception of thermal comfort in patients scheduled to undergo elective open abdominal surgery. This was a randomized controlled study. The study sample comprised 90 patients (30 in the active warming group, 30 in the passive warming group, and 30 in the control group) who agreed to participate and met the research criteria. According to the comparison of patients' vital signs, a statistically significant difference was observed in terms of patients' preoperative body temperature values (χ2 = 56.959; p = 0.000). A comparison of the patients' postoperative thermal comfort perception scores yielded a statistically significant difference (χ2 = 39.693; p = 0.000). Postoperative comfort scores in the active warming group were significantly higher than those in the passive warming and control groups. In conclusion, warming methods are effective in preventing undesirable postoperative hypothermia. The time to reach normothermia after surgery was shorter, vital signs were at a desirable level, and thermal comfort perceptions were higher in patients who were prewarmed. ClinicalTrials.gov (Identifier: NCT04997694).

The Effect of Active Warming on Postoperative Hypothermia on Body Temperature and Thermal Comfort: A Randomized Controlled Trial

PURPOSE

The purpose of this study was to determine the effect of active warming method in temperature control and thermal comfort in hypothermia after surgery.

DESIGN

A randomized controlled trial.

METHODS

The study sample consisted of 64 male and female postanesthesia care unit and intensive care unit neurosurgery postoperative inpatients. The experimental group was warmed using the active warming method, and the control group's routine care was continued via a cotton blanket. Patients were warmed until their tympanic body temperature reached 37°C.

FINDINGS

The time needed to adequately warm patients was approximately twice as short in those who received active warming as compared with the control group. The perception of thermal comfort was significantly higher in the first hour in patients who received the active warming method (P < .05).

CONCLUSIONS

The active warming method resulted in a shorter time to warming in hypothermia after surgery and an increase in the perception of thermal comfort and body temperature.

Reliability and validity of methods in the assessment of cold-induced shivering thermogenesis

PURPOSE

To compare two analytical methods for the estimation of the shivering onset inflection point, segmental regression and visual inspection of data, and to assess the test-retest reliability and validity of four metrics of shivering measurement; oxygen uptake (V̇O₂), electromyography (EMG), mechanomyography (MMG) and bedside shivering assessment scale (BSAS).

METHODS

Ten volunteers attended three identical experimental sessions involving passive deep-body cooling via cold water immersion at 10 °C. V̇O₂, EMG, and MMG were continuously assessed, while the time elapsed at each BSAS stage was recorded. Metrics were graphed as a function of time and rectal temperature (T_re). Inflection points for intermittent and constant shivering were visually identified for every graph and compared to segmental regression.

RESULTS

Excellent agreement was seen between segmental regression and visual inspection (ICC, 0.92). All measurement metrics presented good-to-excellent test-retest reliability (ICC's > 0.75 and 0.90 respectively), with the exception of visual identification of intermittent shivering for V̇O₂ measurement (ICC, 0.73) and segmental regression for EMG measurement (ICC, 0.74). In the assessment of signal-to-noise ratio (SNR), EMG showed the largest SNR at the point of shivering onset followed by MMG and finally V̇O₂.

CONCLUSIONS

Segmental regression provides a successful analytical method for identifying shivering onset. Good-to-excellent reliability can be seen across V̇O₂, EMG, MMG, and BSAS, yet given the observed lag times, SNRs, along with known advantages/disadvantaged of each metric, it is recommended that no single metric is used in isolation. An integrative, real-time measure of shivering is proposed.

Critical Care Management Focused on Optimizing Brain Function After Cardiac Arrest

The discussion of neurocritical care management in post-cardiac arrest syndrome (PCAS) has generally focused on target values used for targeted temperature management (TTM). There has been less attention paid to target values for systemic and cerebral parameters to minimize secondary brain damage in PCAS. And the neurologic indications for TTM to produce a favorable neurologic outcome remain to be determined. Critical care management of PCAS patients is fundamental and essential for both cardiologists and general intensivists to improve neurologic outcome, because definitive therapy of PCAS includes both special management of the cause of cardiac arrest, such as coronary intervention to ischemic heart disease, and intensive management of the results of cardiac arrest, such as ventilation strategies to avoid brain ischemia. We reviewed the literature and the latest research about the following issues and propose practical care recommendations. Issues are (1) prediction of TTM candidate on admission, (2) cerebral blood flow and metabolism and target value of them, (3) seizure management using continuous electroencephalography, (4) target value of hemodynamic stabilization and its method, (5) management and analysis of respiration, (6) sedation and its monitoring, (7) shivering control and its monitoring, and (8) glucose management. We hope to establish standards of neurocritical care to optimize brain function and produce a favorable neurologic outcome.

Analgesia, sedation, and neuromuscular blockade during targeted temperature management after cardiac arrest

The approach to sedation, analgesia, and neuromuscular blockade during targeted temperature management (TTM) remains largely unstudied, forcing clinicians to adapt previous research from other patient environments. During TTM, very little data guide drug selection, doses, and specific therapeutic goals. Sedation should be deep enough to prevent awareness during neuromuscular blockade, but titration is complex as metabolism and clearance are delayed for almost all drugs during hypothermia. Deeper sedation is associated with prolonged intensive care unit (ICU) and ventilator therapy, increased delirium and infection, and delayed wakening which can confound early critical neurological assessments, potentially resulting in erroneous prognostication and inappropriate withdrawal of life support. We review the potential therapeutic goals for sedation, analgesia, and neuromuscular blockade during TTM; the adverse events associated with that treatment; data suggesting that TTM and organ dysfunction impair drug metabolism; and controversies and potential benefits of specific monitoring. We also highlight the areas needing better research to guide our therapy.

Moderate-dose sedation and analgesia during targeted temperature management after cardiac arrest

BACKGROUND

Sedation and analgesia regimens during targeted temperature management (TTM), after cardiac arrest varies widely, are poorly described in the literature and may have a negative impact on outcome. Since implementing TTM in 2005, we have used moderate-dose sedation and describe our experience with this approach.

METHODS

In this retrospective review, we included patients treated with TTM for cardiac arrest at our institution for 2008-2012. Patients received TTM if they did not follow verbal commands following cardiac arrest, regardless of place of arrest or rhythm. Utstein-compatible data were prospectively entered into the International Cardiac Arrest Registry, supplemented by review of nursing, pharmacy, and physical therapy records. We report analgesic and sedative medications and doses during the 24 h of active TTM at 33 °C, resource utilization, and important clinical events.

RESULTS

166 patients treated with TTM after in- and out-of-hospital cardiac arrest with complete data were included. Overall survival was 42 %, median time to following commands was 3 h after rewarming (-6, 14), time to spontaneous breathing trial was 19 h (5-35), time to extubation was 28 h (9-60), and 59 % of survivors were discharged directly home at 13 (10-20) days. The incidence of seizure was 6 %, septic shock 4 %, and pneumonia 32 %. Four survivors required tracheostomy at 8, 8, 12, and 16 days.

CONCLUSIONS

A moderate-dose sedation and analgesia regimen was well tolerated and effective during therapeutic hypothermia after cardiac arrest and is an effective alternative to very deep sedation. We recommend more complete description of sedation and analgesia protocols in future studies, including expanded outcome reporting to include variables affected by sedation therapy. Further study is required to define which sedation approach for TTM may be best.

Electrophysiologic monitoring in acute brain injury

To determine the optimal use and indications of electroencephalography (EEG) in critical care management of acute brain injury (ABI). An electronic literature search was conducted for articles in English describing electrophysiological monitoring in ABI from January 1990 to August 2013. A total of 165 studies were included. EEG is a useful monitor for seizure and ischemia detection. There is a well-described role for EEG in convulsive status epilepticus and cardiac arrest (CA). Data suggest EEG should be considered in all patients with ABI and unexplained and persistent altered consciousness and in comatose intensive care unit (ICU) patients without an acute primary brain condition who have an unexplained impairment of mental status. There remain uncertainties about certain technical details, e.g., the minimum duration of EEG studies, the montage, and electrodes. Data obtained from both EEG and EP studies may help estimate prognosis in ABI patients, particularly following CA and traumatic brain injury. Data supporting these recommendations is sparse, and high quality studies are needed. EEG is used to monitor and detect seizures and ischemia in ICU patients and indications for EEG are clear for certain disease states, however, uncertainty remains on other applications.

Therapeutic hypothermia after nonshockable cardiac arrest: the HYPERION multicenter, randomized, controlled, assessor-blinded, superiority trial

BACKGROUND

Meta-analyses of nonrandomized studies have provided conflicting data on therapeutic hypothermia, or targeted temperature management (TTM), at 33°C in patients successfully resuscitated after nonshockable cardiac arrest. Nevertheless, the latest recommendations issued by the International Liaison Committee on Resuscitation and by the European Resuscitation Council recommend therapeutic hypothermia. New data are available on the adverse effects of therapeutic hypothermia, notably infectious complications. The risk/benefit ratio of therapeutic hypothermia after nonshockable cardiac arrest is unclear.

METHODS

HYPERION is a multicenter (22 French ICUs) trial with blinded outcome assessment in which 584 patients with successfully resuscitated nonshockable cardiac arrest are allocated at random to either TTM between 32.5 and 33.5°C (therapeutic hypothermia) or TTM between 36.5 and 37.5°C (therapeutic normothermia) for 24 hours. Both groups are managed with therapeutic normothermia for the next 24 hours. TTM is achieved using locally available equipment. The primary outcome is day-90 neurological status assessed by the Cerebral Performance Categories (CPC) Scale with dichotomization of the results (1 + 2 versus 3 + 4 + 5). The primary outcome is assessed by a blinded psychologist during a semi-structured telephone interview of the patient or next of kin. Secondary outcomes are day-90 mortality, hospital mortality, severe adverse events, infections, and neurocognitive performance. The planned sample size of 584 patients will enable us to detect a 9% absolute difference in day-90 neurological status with 80% power, assuming a 14% event rate in the control group and a two-sided Type 1 error rate of 4.9%. Two interim analyses will be performed, after inclusion of 200 and 400 patients, respectively.

DISCUSSION

The HYPERION trial is a multicenter, randomized, controlled, assessor-blinded, superiority trial that may provide an answer to an issue of everyday relevance, namely, whether TTM is beneficial in comatose patients resuscitated after nonshockable cardiac arrest. Furthermore, it will provide new data on the tolerance and adverse events (especially infectious complications) of TTM at 32.5-33.5°C.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01994772 .

Feasibility of bispectral index monitoring to guide early post-resuscitation cardiac arrest triage

INTRODUCTION

Triage after resuscitation from cardiac arrest is hindered by reliable early estimation of brain injury. We evaluated the performance of a triage model based on early bispectral index (BIS) findings and cardiac risk classes.

METHODS

Retrospective evaluation of serial patients resuscitated from cardiac arrest, unable to follow commands, and undergoing hypothermia. Patients were assigned to a cardiac risk group: STEMI, VT/VF shock, VT/VF no shock, or PEA/asystole, and to a neurological dysfunction group, based on the BIS score following first neuromuscular blockade (BISi), and classified as BISi>20, BISi 10-20, or BISi<10. Cause of death was described as neurological or circulatory.

RESULTS

BISi in 171 patients was measured at 267(±177)min after resuscitation and 35(±1.7)°C. BISi<10 suffered 82% neurological-cause and 91% overall mortality, BISi 10-20 35% neurological and 55% overall mortality, and BISi>20 12% neurological and 36% overall mortality. 33 patients presented with STEMI, 15 VT/VF-shock, 41 VT/VF-no shock, and 80 PEA/asystole. Among BISi>20 patients, 75% with STEMI underwent urgent cardiac catheterization (cath) and 94% had good outcome. When BISi>20 with VT/VF and shock, urgent cath was infrequent (33%), and 4 deaths (44%) were uniformly of circulatory etiology. Of 56 VT/VF patients without STEMI, 24 were BISi>20 but did not undergo urgent cath - 5(20.8%) of these had circulatory-etiology death. Circulatory-etiology death also occurred in 26.5% BIS>20 patients with PEA/asystole. When BISi<10, a neurological etiology death dominated independent of cardiac risk group.

CONCLUSIONS

Neurocardiac triage based on very early processed EEG (BIS) is feasible, and may identify patients appropriate for individualized post-resuscitation care. This and other triage models warrant further study.

The evidence base for nursing care and monitoring of patients during therapeutic temperature management

Therapeutic temperature management (TTM) is fast becoming a primary management strategy for a variety of medical conditions treated in critical care settings throughout the world. Nurses who provide direct care and who are tasked with developing multidisciplinary protocols and pathways are struggling to collate evidence from which to support specific nursing interventions. The aim of this project was to create the first comprehensive set of evidence-based guidelines specific to nursing care of the patient for whom TTM is medically necessary. Evidence-based nursing practice summaries are provided for nine nursing content areas: interventions to manage temperature, monitoring temperature, neurologic, cardiac, pulmonary, skin care, gastrointestinal/endocrine, laboratory findings, and general considerations for nursing care.

Initial bispectral index may identify patients who will awaken during therapeutic hypothermia after cardiac arrest: a retrospective pilot study

AIM

Patients sustain a range of neurologic injuries after cardiac arrest, and determining which patients should be treated with therapeutic hypothermia (TH) is complex, often confounded by sedation and neuromuscular blockade (NMB). We evaluated bispectral index (BIS) monitoring as a tool to identify adult patients that awakened during therapeutic hypothermia.

METHODS

Review of prospectively collected registry data, with retrospective chart review of patient descriptions during hypothermia. Data are presented as median (interquartile range).

RESULTS

7 of 309 patients (2.2%) treated with TH over 6 years awoke (followed commands) prior to completing hypothermia. Median age was 58 (54-66) years; 71% were male, cardiac arrest was witnessed in 6 (86%) and out-of-hospital in 6 (86%), and 4 patients (57%) were transferred from another hospital. 5 patients (71%) had an initial rhythm of ventricular tachycardia or fibrillation, time to return of spontaneous circulation was 17 (12-23)min. The BIS value after first NMB dose during TH was 63, 45, 43, 52, 62, 54, and 42 (median 52, IQR 44-58, 95% confidence interval 46-58). The median BIS value in the remaining data set (n=302) was 18 (6-36), p<0.001, and only 6% of BIS1 values were >46.

CONCLUSION

Patients who awakened early had higher BIS values after the first dose of NMB. Processed EEG values after cardiac arrest may provide additional information that could assist with determining best treatment.