Background: Despite possible differences between out of hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA) populations, most available data is taken from analyses of OHCA patients (pts). More data about predictors of return of spontaneous circulation (ROSC) and in-hospital mortality after IHCA is needed. A high serum lactate is frequent in OHCA patients and is associated with poor outcome. However, little is known about its possible effect in patients after IHCA.

Aim: To investigate the incidence of hyperlactatemia and some other parameters and their probable influence on in-hospital outcome in pts after cardiopulmonary resuscitation (CPR) due to IHCA.

Design: We retrospectively analyzed consecutive pts who were between 2021 and 2022 cardiopulmonary resuscitated at our center. We separated them into two groups (the OHCA group and the IHCA one) and compared them regarding predictors of in-hospital outcomes.

Results: 145 pts, who underwent cardiopulmonary resuscitation at our center were analyzed (characteristics are listed in table 1). ROSC occurred in 86 pts (59.3%). In-hospital mortality rate was 71.1% (103 pts). This was comparable in both groups (69.1% in the IHCA group and 76.5% in the OHCA group, p 0.410). Neurologic injury was described in 2 pts (both from the OHCA group, p 0.354). A severely high serum lactate level (defined as lactate >100 mg/dl) at baseline (less than two hours after CPR onset) was associated with high mortality in both groups (however, it was statistically significant only in the IHCA group; p <0.001 and 0.063 respectively). Whereas the same high level of serum lactate 2 hours (h) after CPR onset, was associated with high mortality in both groups (both statistically significant; p 0.002 and 0.012). Extreme acidosis (defined as pH<7), both initially and in ROSC pts 2h after CPR onset, was similarly associated with high mortality in both groups (p values are in table 3). Additionally, a long duration of CPR more than 45 minutes was also a predictor of mortality (table 3).

Conclusions: In-hospital mortality rates seem to be comparable between IHCA and OHCA pts. Severe hyperlactatemia, both initially and in ROSC pts 2 hours after CPR onset, was associated with poor in-hospital outcome (statistically significant high mortality). Other predictors of in-hospital mortality in both groups were long CPR duration more than 45 minutes as well as extreme acidosis.