Can Blood Ammonia Level, Prehospital Time, and Return of Spontaneous Circulation Predict Neurological Outcomes of Out-of-Hospital Cardiac Arrest Patients? A Nationwide, Retrospective Cohort Study

Intra-arrest blood-based biomarkers for out-of-hospital cardiac arrest: A scoping review

Objective

Blood-based biomarkers play a central role in the diagnosis and treatment of critically ill patients, yet none are routinely measured during the intra-arrest phase of out-of-hospital cardiac arrest (OHCA). Our objective was to describe methodological aspects, sources of evidence, and gaps in research surrounding intra-arrest blood-based biomarkers for OHCA.

Methods

We used scoping review methodology to summarize existing literature. The protocol was designed a priori following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews. Inclusion criteria were peer-reviewed scientific studies on OHCA patients with at least one blood draw intra-arrest. We excluded in-hospital cardiac arrest and animal studies. There were no language, date, or study design exclusions. We conducted an electronic literature search using PubMed and Embase and hand-searched secondary literature. Data charting/synthesis were performed in duplicate using standardized data extraction templates.

Results

The search strategy identified 11,834 records, with 118 studies evaluating 105 blood-based biomarkers included. Only eight studies (7%) had complete reporting. The median number of studies per biomarker was 2 (interquartile range 1-4). Most studies were conducted in Asia (63 studies, 53%).  Only 22 studies (19%) had blood samples collected in the prehospital setting, and only six studies (5%) had samples collected by paramedics. Pediatric patients were included in only three studies (3%). Out of eight predefined biomarker categories of use, only two were routinely assessed: prognostic (97/105, 92%) and diagnostic (61/105, 58%).

Conclusions

Despite a large body of literature on intra-arrest blood-based biomarkers for OHCA, gaps in methodology and knowledge are widespread.

Association between prehospital airway type and oxygenation and ventilation in out-of-hospital cardiac arrest

OBJECTIVES

This study aimed to evaluate the association between prehospital airway type and oxygenation and ventilation in out-of-hospital cardiac arrest (OHCA).

METHODS

This retrospective observational study included OHCA patients who visited the emergency departments (EDs) between October 2015 and June 2021. The study groups were categorized according to the prehospital airway type: endotracheal intubation (ETI), supraglottic airway (SGA), or bag-valve-mask ventilation (BVM). The primary outcome was good oxygenation: partial pressure of oxygen (PaO2) ≥ 60 mmHg on the first arterial blood gas (ABG) test. The secondary outcome was good ventilation: partial pressure of carbon dioxide (PaCO2) ≤ 45 mmHg. Multivariate logistic regression was conducted to calculate the adjusted odds ratio (AOR) and 95% confidence interval (CI).

RESULTS

A total of 7,372 patients were enrolled during the study period: 1,819 patients treated with BVM, 706 with ETI, and 4,847 who underwent SGA. In multivariable logistic regression analysis for good oxygenation outcomes, the ETI group showed a higher AOR than the BVM group (AOR [95% CIs]: 1.30 [1.06-1.59] in ETI and 1.05 [0.93-1.20] in SGA groups). Regarding good ventilation, the ETI group showed a higher AOR, and the SGA group showed a lower AOR compared to the BVM group (AOR [95% CIs] 1.33 [1.02-1.74] in the ETI and 0.83 (0.70-0.99) in the SGA groups). There was no significant difference in survival to discharge.

CONCLUSIONS

ETI was significantly associated with good oxygenation and good ventilation compared to BVM in patients with OHCA, particularly during longer transports. This should be taken into consideration when deciding the prehospital advanced airway management in patients with OHCA.