Blood ammonia is a predictive biomarker of neurologic outcome in cardiac arrest patients treated with therapeutic hypothermia

2024 RECOVER Guidelines: Monitoring. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR

OBJECTIVE

To systematically review evidence on and devise treatment recommendations for patient monitoring before, during, and following CPR in dogs and cats, and to identify critical knowledge gaps.

DESIGN

Standardized, systematic evaluation of literature pertinent to peri-CPR monitoring following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by Evidence Evaluators, and findings were reconciled by Monitoring Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk:benefit relationship, and clinical feasibility. This process was implemented using an Evidence Profile Worksheet for each question that included an introduction, consensus on science, treatment recommendations, justification for these recommendations, and important knowledge gaps. A draft of these worksheets was distributed to veterinary professionals for comment for 4 weeks prior to finalization.

SETTING

Transdisciplinary, international collaboration in university, specialty, and emergency practice.

RESULTS

Thirteen questions pertaining to hemodynamic, respiratory, and metabolic monitoring practices for identification of cardiopulmonary arrest, quality of CPR, and postcardiac arrest care were examined, and 24 treatment recommendations were formulated. Of these, 5 recommendations pertained to aspects of end-tidal CO2 (ETco2) measurement. The recommendations were founded predominantly on very low quality of evidence, with some based on expert opinion.

CONCLUSIONS

The Monitoring Domain authors continue to support initiation of chest compressions without pulse palpation. We recommend multimodal monitoring of patients at risk of cardiopulmonary arrest, at risk of re-arrest, or under general anesthesia. This report highlights the utility of ETco2 monitoring to verify correct intubation, identify return of spontaneous circulation, evaluate quality of CPR, and guide basic life support measures. Treatment recommendations further suggest intra-arrest evaluation of electrolytes (ie, potassium and calcium), as these may inform outcome-relevant interventions.

Hemoglobin as a prognostic marker for neurological outcomes in post-cardiac arrest patients: a meta-analysis

The aim of this study was to investigate the relationship between serum level of hemoglobin and neurological outcomes following cardiac arrest. Relevant studies were identified by searching electronic databases including PubMed, Web of Science, Cochrane Library, and Embase from June 2012 through April 2023. Articles were rigorously reviewed for their study inclusion and exclusion criteria. Pooled effect date was determined using the standardized mean difference (SMD) and 95% confidence intervals (CI). The Newcastle-Ottawa Scale was used to evaluate study quality. Subgroup analyses were conducted to determine confounding factors affecting patient outcomes. Study heterogeneity, sensitivity, and publication bias were also determined.This meta-analysis included 11 studies involving 2519 patients. Our results suggest that high serum level of hemoglobin may improve neurological prognosis(SMD = 0.60, 95%CI = 0.49-0.71, I2 = 10.85). The findings of this study indicate that serum level of hemoglobin may be associated with better neurological prognosis, perhaps an appropriate increase in serum haemoglobin levels can improve the neurological prognosis of patients in cardiac arrest.

Serum potassium level on hospital arrival and survival after out-of-hospital cardiac arrest: The CRITICAL study in Osaka, Japan

BACKGROUND

Little is known about the association between serum potassium level on hospital arrival and neurological outcome after out-of-hospital cardiac arrest (OHCA). We investigated whether the serum potassium level on hospital arrival had prognostic indications for patients with OHCA.

METHODS

This prospective, multicenter observational study conducted in Osaka, Japan (CRITICAL study) enrolled consecutive patients with OHCA transported to 14 participating institutions from 2012 to 2016. We included adult patients aged ⩾18 years with OHCA of cardiac origin who achieved return of spontaneous circulation and whose serum potassium level on hospital arrival was available. Based on the serum potassium level, patients were divided into four quartiles: Q1 (K ⩽3.8 mEq/L), Q2 (3.8< K⩽4.5 mEq/L), Q3 (4.5< K⩽5.6 mEq/L) and Q4 (K >5.6 mEq/L). The primary outcome was one-month survival with favorable neurological outcome, defined as cerebral performance category scale 1 or 2.

RESULTS

A total of 9822 patients were registered, and 1516 of these were eligible for analyses. The highest proportion of favorable neurological outcome was 44.8% (189/422) in Q1 group, followed by 30.3% (103/340), 11.7% (44/375) and 4.5% (17/379) in the Q2, Q3 and Q4 groups, respectively (p<0.001). In the multivariable analysis, the proportion of favorable neurological outcome decreased as the serum potassium level increased (p<0.001).

CONCLUSIONS

High serum potassium level was significantly and dose-dependently associated with poor neurological outcome. Serum potassium on hospital arrival would be one of the effective prognostic indications for OHCA achieving return of spontaneous circulation.

Blood Lactate or Lactate Clearance: Which Is Robust to Predict the Neurological Outcomes after Cardiac Arrest? A Systematic Review and Meta-Analysis

Aims

Lactate and lactate clearance were supposed to be associated with cardiac arrest outcomes, but studies obtained different results. Thus, we conducted this meta-analysis to investigate the association between lactate or lactate clearance and neurological outcomes and their usefulness for prediction of neurological outcomes.

Methods

We conducted a systematic search in PubMed, Web of science, EMBASE, Medline, and Google Scholar until May 1, 2018, for relevant studies. Studies reporting lactate, lactate clearance on admission, or other time points after admission associated with neurological outcomes were included in our analysis. Pooled effect date was shown as weighed mean difference (WMD) and 95% confidence interval (CI). To measure the usefulness of lactate on admission to predict neurological outcomes, we also pooled the data of diagnostic test.

Results

23 studies involving 6720 cardiac arrest (CA) patients were included. Results from our analysis indicated that patients with good neurological outcomes tended to have a lower lactate level on admission (WMD: -2.66 mmol/L, 95%CI: -3.39 to -1.93) and 12h, 24h, and 48h after admission (P<0.001). Furthermore, the pooled AUC for lactate level on admission to predict neurological outcomes was 0.77 (95%CI: 0.73-0.80). However, a significant association between lactate clearance and neurological outcomes was only found in 24h but not 12h lactate clearance rate.

Conclusions

Lactate levels on admission and all time points up to 48h were associated with neurological outcomes after CA, whereas the association between lactate clearance and neurological outcomes was not so stable. Lactate was a more robust surrogate marker than lactate clearance to predict neurological outcomes after CA.

Prognostic Impact of Serum Albumin Concentration for Neurologically Favorable Outcome in Patients Treated with Targeted Temperature Management After Out-of-Hospital Cardiac Arrest: A Multicenter Prospective Study

To assess whether serum albumin concentration measured upon hospital arrival was useful as an early prognostic biomarker for neurologically favorable outcome in out-of-hospital cardiac arrest (OHCA) patients treated with target temperature management (TTM). This prospective, multicenter observational study (The CRITICAL Study) carried out between July 1, 2012 and December 31, 2014 in Osaka Prefecture, Japan involving 13 critical care medical centers (CCMCs) and one non-CCMC with an emergency department. This study included patients ≥18 years of age who underwent an OHCA, for whom resuscitation was attempted by Emergency Medical Services personnel and were then transported to participating institutions, and who were then treated with TTM. Based on the serum albumin concentration upon hospital arrival, involved patients were divided into four quartiles (Q1-Q4) defined as Q1 (<3.0 g/dL), Q2 (≥3.0, <3.4 g/dL), Q3 (≥3.4, <3.8 g/dL), and Q4 (≥3.8 g/dL). The primary outcome of this study was 1-month survival with neurologically favorable outcome defined by cerebral performance category 1 or 2. During the study period, a total of 327 were eligible for our analysis. The overall proportion of neurologically favorable outcome was 33.0% (108/327). The Q4 group had the highest proportion of neurologically favorable outcome (52.5% [48/91]), followed by Q3 (34.5% [30/87]), Q2 (27.3% [21/77]), and Q1 (12.5% [9/72]). The multivariable logistic regression analysis demonstrated that the proportion of neurologically favorable outcome was significantly higher in the Q4 group than that in the Q1 group (adjusted odds ratio 10.39; 95% confidence interval 3.36-32.17). The adjusted proportion of neurologically favorable outcome increased in a stepwise fashion across increasing quartiles (p < 0.001). In this study, higher serum albumin concentration upon hospital arrival had a positive association with neurologically favorable outcome after OHCA in a dose-dependent manner.

Initial blood pH during cardiopulmonary resuscitation in out-of-hospital cardiac arrest patients: a multicenter observational registry-based study

BACKGROUND

When an out-of-hospital cardiac arrest (OHCA) patient receives cardiopulmonary resuscitation (CPR) in the emergency department (ED), blood laboratory test results can be obtained by using point-of-care testing during CPR. In the present study, the relationship between blood laboratory test results during CPR and outcomes of OHCA patients was investigated.

METHODS

This study was a multicenter retrospective analysis of prospective registered data that included 2716 OHCA patients. Data from the EDs of three university hospitals in different areas were collected from January 2009 to December 2014. Univariate and multivariable analyses were conducted to elucidate the factors associated with survival to discharge and neurological outcomes. A final analysis was conducted by including patients who had no prehospital return of spontaneous circulation and those who underwent rapid blood laboratory examination during CPR.

RESULTS

Overall, 2229 OHCA patients were included in the final analysis. Among them, the rate of survival to discharge and a good Cerebral Performance Categories Scale score were 14% and 4.4%, respectively. The pH level was independently related to survival to hospital discharge (adjusted OR 6.287, 95% CI 2.601-15.197; p < 0.001) and good neurological recovery (adjusted OR 15.395, 95% CI 3.439-68.911; p < 0.001). None of the neurologically intact patients had low pH levels (< 6.8) or excessive potassium levels (> 8.5 mEq/L) during CPR.

CONCLUSIONS

Among the blood laboratory test results during CPR of OHCA patients, pH and potassium levels were observed as independent factors associated with survival to hospital discharge, and pH level was considered as an independent factor related to neurological recovery.

Decreased a disintegrin-like and metalloprotease with thrombospondin type 1 motif 13 activity and neurologic outcome in patients with successful resuscitation of out-of-hospital cardiac arrest: A prospective observational study

PURPOSE

The purpose of this study is to investigate the association between a disintegrin-like and metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13) and neurologic outcome in patients with resuscitation of out-of-hospital cardiac arrest (R-OHCA).

MATERIALS AND METHODS

A prospective observational study of adult patients with R-OHCA was conducted. Plasma activity of ADAMTS13 and inflammatory markers, an immunologic marker, and a marker of endothelial damage were measured on admission and day 2. Neurologic outcome was evaluated using the Cerebral Performance Categories on day 90.

RESULTS

Plasma activity of ADAMTS13 on day 2 was lower in patients with poor neurologic outcome (n = 18) than that in those with good neurologic outcome (n = 16; P = .008). It was also lower in 28-day nonsurvivors (n = 12) than in survivors (n = 21; P = .019). Soluble thrombomodulin showed a strong correlation with ADAMTS13 (P = .021). Furthermore, ADAMTS13 activity was negatively correlated with the Sequential Organ Failure Assessment score (P < .001), levels of high-mobility group box 1 (P = .028), and levels of interleukin 6 (P = .047) but positively correlated with the monocyte expression of human leukocyte antigen DR (P = .023).

CONCLUSION

Decreased ADAMTS13 activity was associated with poor neurologic outcome, high mortality, and worsened immune-inflammatory status in patients with R-OHCA. These results suggest that ADAMTS13 may have pathophysiologic relevance in postcardiac arrest syndrome.

The Measurement of Ammonia in Human Breath and its Potential in Clinical Diagnostics

Ammonia is an important component of metabolism and is involved in many physiological processes. During normal physiology, levels of blood ammonia are between 11 and 50 µM. Elevated blood ammonia levels are associated with a variety of pathological conditions such as liver and kidney dysfunction, Reye's syndrome and a variety of inborn errors of metabolism including urea cycle disorders (UCD), organic acidaemias and hyperinsulinism/hyperammonaemia syndrome in which ammonia may reach levels in excess of 1 mM. It is highly neurotoxic and so effective measurement is critical for assessing and monitoring disease severity and treatment. Ammonia is also a potential biomarker in exercise physiology and studies of drug metabolism. Current ammonia testing is based on blood sampling, which is inconvenient and can be subject to significant analytical errors due to the quality of the sample draw, its handling and preparation for analysis. Blood ammonia is in gaseous equilibrium with the lungs. Recent research has demonstrated the potential use of breath ammonia as a non-invasive means of measuring systemic ammonia. This requires measurement of ammonia in real breath samples with associated temperature, humidity and gas characteristics at concentrations between 50 and several thousand parts per billion. This review explores the diagnostic applications of ammonia measurement and the impact that the move from blood to breath analysis could have on how these processes and diseases are studied and managed.

A QCM-based ‘on–off’ mechanistic study of gas adsorption by plasmid DNA and DNA–[Bmim][PF6] construct

The study of the adsorption behavior of disease markers such as ammonia (NH₃) and acetaldehyde (CH₃CHO) with biomaterials has been presented to enable the development of self-diagnosis technologies, among others.

Severe acidemia on arrival not predictive of neurologic outcomes in post-cardiac arrest patients

PURPOSE

This study aimed to determine whether severe acidemia (pH <7.2) on arrival at the emergency department (ED) is a predictive factor for neurologic outcomes of post-cardiac arrest patients treated with targeted temperature management (TTM).

MATERIALS AND METHODS

Data in the National Disaster Medical Center, a tertiary care hospital, were used to perform a case-control study on post-cardiac arrest patients treated with TTM from January 2013 to April 2015. The case group comprised patients with good neurologic outcomes (cerebral performance categories 1 and 2), whereas the control group comprised patients with poor neurologic outcomes (cerebral performance categories 3-5). Exposure was defined as arterial pH less than 7.2 on arrival at the ED.

RESULTS

We identified 32 patients matching our criteria, of which 13 had good outcomes and 19 poor outcomes. Arterial pH on arrival was not significantly associated with neurologic outcomes (P = .47; odds ratio, 0.5; 95% confidence interval, 0.09-2.61). In 24 patients with cardiogenic causes of cardiac arrest, pH on arrival was not significantly associated with neurologic outcomes (P = .68; odds ratio, 0.5; 95% confidence interval, 0.09-2.73) after matched-pair analysis by age, sex, and presence of light reflex.

CONCLUSION

Severe acidemia on arrival at the ED is not a significant predictive factor for neurologic outcomes in post-cardiac arrest patients treated with TTM, particularly in patients with cardiogenic causes of cardiac arrest. These results suggest that treatment should not be withheld in post-cardiac arrest patients with severe acidemia.

Early prognostication markers in cardiac arrest patients treated with hypothermia

BACKGROUND AND PURPOSE

Established prognostication markers, such as clinical findings, electroencephalography (EEG) and biochemical markers, used by clinicians to predict neurological outcome after cardiac arrest (CA) are altered under therapeutic hypothermia (TH) conditions and their validity remains uncertain.

METHODS

MEDLINE and Embase were searched for evidence on the current standards for neurological outcome prediction for out-of-hospital CA patients treated with TH and the validity of a wide range of prognostication markers. Relevant studies that suggested one or several established biomarkers and multimodal approaches for prognostication are included and reviewed.

RESULTS

Whilst the prognostic accuracy of various tests after TH has been questioned, pupillary light reflexes and somatosensory evoked potentials are still strongly associated with negative outcome for early prognostication. Increasingly, EEG background activity has also been identified as a valid predictor for outcome after 72 h after CA and a preferred prognostic method in clinical settings. Neuroimaging techniques, such as magnetic resonance imaging and computed tomography, can identify functional and structural brain injury but are not readily available at the patient's bedside because of limited availability and high costs.

CONCLUSIONS

A multimodal algorithm composed of neurological examination, EEG-based quantitative testing and somatosensory evoked potentials, in conjunction with newer magnetic resonance imaging sequences, if available, holds promise for accurate prognostication in CA patients treated with TH. In order to avoid premature withdrawal of care, prognostication should be performed more than 72 h after CA.

Correlation between initial serum levels of lactate after return of spontaneous circulation and survival and neurological outcomes in patients who undergo therapeutic hypothermia after cardiac arrest

OBJECTIVES

We analysed the relationship between serum levels of lactate within 1h of return of spontaneous circulation (ROSC) and survival and neurological outcomes in patients who underwent therapeutic hypothermia (TH).

METHODS

This was a multi-centre retrospective and observational study that examined data from the first Korean Hypothermia Network (KORHN) registry from 2007 to 2012. The inclusion criteria were out-of-hospital cardiac arrest (OHCA) and examination of serum levels of lactate within 1h after ROSC, taken from KORHN registry data. The primary endpoint was survival outcome at hospital discharge, and the secondary endpoint was poor neurological outcome (Cerebral Performance Category, CPC, 3-5) at hospital discharge. Initial lactate levels and other variables collected within 1h of ROSC were analysed via multivariable logistic regression.

RESULTS

Data from 930 cardiac arrest patients who underwent TH were collected from the KORHN registry. In a total of 443 patients, serum levels of lactate were examined within 1h of ROSC. In-hospital mortality was 289/443 (65.24%), and 347/443 (78.33%) of the patients had CPCs of 3-5 upon hospital discharge. The odds ratios of lactate levels for CPC and in-hospital mortality were 1.072 (95% confidence interval (CI) 1.026-1.121) and 1.087 (95% CI=1.031-1.147), respectively, based on multivariate ordinal logistic regression analyses.

CONCLUSION

High levels of lactate in serum measured within 1h of ROSC are associated with hospital mortality and high CPC scores in cardiac arrest patients treated with TH.

Better lactate clearance associated with good neurologic outcome in survivors who treated with therapeutic hypothermia after out-of-hospital cardiac arrest

Introduction

Several methods have been proposed to evaluate neurological outcome in out-of-hospital cardiac arrest (OHCA) patients. Blood lactate has been recognized as a reliable prognostic marker for trauma, sepsis, or cardiac arrest. The objective of this study was to examine the association between initial lactate level or lactate clearance and neurologic outcome in OHCA survivors who were treated with therapeutic hypothermia.

Methods

This retrospective cohort study included patients who underwent protocol-based 24-hour therapeutic hypothermia after OHCA between January 2010 and March 2012. Serum lactate levels were measured at the start of therapy (0 hours), and after 6 hours, 12 hours, 24 hours, 48 hours and 72 hours. The 6 hour and 12 hour lactate clearance were calculated afterwards. Patients’ neurologic outcome was assessed at one month after cardiac arrest; good neurological outcome was defined as Cerebral Performance Category one or two. The primary outcome was an association between initial lactate level and good neurologic outcome. The secondary outcome was an association between lactate clearance and good neurologic outcome in patients with initial lactate level >2.5 mmol/l.

Results

Out of the 76 patients enrolled, 34 (44.7%) had a good neurologic outcome. The initial lactate level showed no significant difference between good and poor neurologic outcome groups (6.07 ±4 .09 mmol/L vs 7.13 ± 3.99 mmol/L, P = 0.42), However, lactate levels at 6 hours, 12 hours, 24 hours, and 48 hours in the good neurologic outcome group were lower than in the poor neurologic outcome group (3.81 ± 2.81 vs 6.00 ± 3.22 P <0.01, 2.95 ± 2.07 vs 5.00 ± 3.49 P <0.01, 2.17 ± 1.24 vs 3.86 ± 3.92 P <0.01, 1.57 ± 1.02 vs 2.21 ± 1.35 P = 0.03, respectively). The secondary analysis showed that the 6-hour and 12-hour lactate clearance was higher for good neurologic outcome patients (35.3 ± 34.6% vs 6.89 ± 47.4% P = 0.01, 54.5 ± 23.7% vs 25.6 ± 43.7% P <0.01, respectively). After adjusting for potential confounding variables, the 12-hour lactate clearance still showed a statistically significant difference (P = 0.02).

Conclusion

The lactate clearance rate, and not the initial lactate level, was associated with neurological outcome in OHCA patients after therapeutic hypothermia.