Abstract Body: Background: Despite national recommendations against the routine use of sodium bicarbonate (SB) during cardiac arrest, SB is used in about 50% of both pediatric and adult IHCA, making it the second most used drug, after epinephrine.

Aims: To explore clinician practices and beliefs surrounding intra-arrest SB administration.

Hypothesis: We hypothesized that SB use would vary by specialty, and that indications for intra-arrest SB not endorsed by AHA guidelines would be common.

Methods: We performed a mixed methods electronic survey amongst adult and pediatric intensive care unit (ICU), emergency medicine (EM) and anesthesia attendings at two local institutions in Boston, MA from October 3^rd to December 15^th, 2023. Likert scale responses for likelihood of giving SB in 2 cardiac arrest scenarios were compared using a Chi-squared test. These responses were dichotomized to reflect those who would “probably” or “definitely” give SB versus those who would not, and respondent characteristics were compared. For the open-ended items, we performed qualitative thematic analysis.

Results: Of 356 physicians invited, 224 (63%) responded. The likelihood of giving SB in Scenario 1 (10-minute asystolic arrest) and Scenario 2 (20-minute asystolic arrest) differed (Figure 1), with 54/224 (24%) respondents indicating they would give SB in Scenario 1 and 110 (49%) for Scenario 2. Additionally, likelihood of giving SB in Scenario 1 varied based on practice location (p = 0.025) with the lowest rates in pediatric and adult EM (8% and 10%, respectively) and the highest amongst those in adult ICUs (38%). These differences persisted for Scenario 2 (p = 0.001). SB use in Scenario 1 also decreased with increasing years of experience (p = 0.032). The most reported indications for SB were: hyperkalemia (78%); metabolic acidosis (76%) with a median reported threshold pH of 7.1 (IQR: 7, 7.2); tricyclic anti-depressant overdose (71%); and arrest duration (64%) with a median reported threshold of 15 minutes (IQR: 10, 20). In the qualitative analysis, additional themes emerged for reasons respondents give SB, including specific diagnoses, arrest rhythms, team dynamics and beliefs about the physiological effects of SB.

Conclusions: Physicians reported significant practice variations surrounding cardiac arrest management with SB, including several indications for SB which are not supported by national cardiac arrest guidelines.