Methods
The study was approved by the Ethics Committee for the Non-Invasive Research at the Gulhane Health Sciences University (Committee IRB approval number: 2020/06-decision no: 2020/126).
Study design and patient selection
All non-traumatic cardiac arrest patients admitted to the emergency department from November 1 2016 to January 31 2020 were screened in the electronic patient management system (FONET®, Information Technology Incorporation, Turkey). Patient charts were screened, as well as an electronic patient management system. Patients who were younger than 18 years and who had missing information were excluded. All non-traumatic CA patients without the exclusion criteria were included in the study (Figure-1).
Age, gender, complete blood count (CBC) parameters of the patients, routine biochemistry measurements, coagulation parameters, and blood gas analysis, cardiac markers, whether ROSC was achieved or not, the initial rhythm [Asystole, Ventricular Fibrillation (VF), Pulseless Ventricular Tachycardia (VT), Pulseless Electrical Activity (PEA)], duration of CPR (min), and hospital admission status were recorded. The patients were divided into two groups as patients in whom ROSC was achieved (ROSC group) or those in whom ROSC was not achieved (non-ROSC group). ROSC was defined as spontaneous circulation and was achieved longer than 20 min. The ROSC group was also divided into two subgroups as survivors (discharged from the hospital) and non-survivors (mortality occurred during hospital stay).
Power analysis
The sample size was calculated with an alpha value of 0.05, 80% power, an enrollment ratio of 1, and COHb values of 0.9 in group 1 (ROSC group) and 0.54 in group 2 (no-ROSC group), yielding that 26 patients in either group making a total of 52 participants would be included in the study (17,18).
Laboratory analysis
By the protocol of the emergency service where the study was conducted, blood samples are taken simultaneously for CBC, routine biochemistry, blood gas analysis, cardiac markers, and coagulation parameters within the first 4 mins of the onset of CPR.
CBC (Beckman Coulter Unicell DxH 800, CA 92821 USA), blood gas parameters (Radiometer ABL800 FLEX, 2700 Bronshoj Denmark), routine biochemistry (Beckman Coulter AU680, CA 92821 USA), cardiac Troponin (cTn), creatine kinase MB isoenzymes (CKMB) (Beckman Coulter DxI 800 Access immunoassay systems, CA 92821 USA), PTZ-INR, and D-Dimer (Sysmex CS-2500, Kobe 651-0073 Japan) were measured in the emergency biochemistry laboratory.
Statistical analysis
The categorical variables were presented as frequency and percentages. Continuous variables were presented as mean ± standard deviation. The Kolmogorov Smirnov test was used for testing whether the variables were distributed normally. Student’s t-test was used for binary comparison of continuous variables conforming to the normal distribution, Mann-Whitney U test for non-compliant ones, and Chi-square test for comparison of categorical data. A p-value of < 0.05 was considered statistically significant. The statistical analysis software was SPSS Statistics for Windows, version 22.0 (SPSS Statistics for Windows, Version 22.0. IBM Corp., Armonk, N.Y., USA).