Study stopped early after consultation with DSMB

This study is to evaluate whether thiamine can increase oxygen consumption and lower lactate in patients who initially survive an in-hospital cardiac arrest. Patients who are successfully resuscitated after an in-hospital cardiac arrest and who are on mechanical ventilation in the intensive care unit will be enrolled, and will get either thiamine or placebo. Their oxygen consumption and lactate will be measured at serial time points and compared between groups. The investigators' hypothesis is that thiamine will help restore the body's ability to metabolize oxygen normally (aerobic metabolism), leading to an increase in oxygen consumption and a decrease in lactate.

In-hospital cardiac arrest often leads to shock and organ failure, and low oxygen consumption and high lactate are associated with worse outcome. Thiamine is a B vitamin necessary to maintain the body's ability to use oxygen effectively, and the investigators have found that many patients are thiamine deficient after cardiac arrest. The investigators have also found that thiamine can decrease lactate in thiamine-deficient patients who are critically ill. Patients in this study will be randomized to receive either thiamine or placebo every 12 hours for 2 days after surviving an in-hospital cardiac arrest. The investigators will measure oxygen consumption continuously during that time with a monitor attached to the ventilator tubing, and will also measure lactate and other lab values at several time points.

Inclusion Criteria:

• Adult patient (age > 18 years)
• Cardiac arrest occurring while admitted to the hospital, with sustained (>20 minutes) return of spontaneous circulation (ROSC)
• Mechanically ventilated at the time of enrollment
• Within 12 hours of cardiac arrest event

Exclusion Criteria:

• Clinical indication for thiamine administration (alcoholism, known or highly suspected deficiency) or treatment with thiamine beyond the amount found in a standard multivitamin within the last 10 days
• Comfort measures only or anticipated withdrawal of support within 24 hours
• Severe agitation
• Protected populations (pregnant women, prisoners)

From enrollment to time of hospital discharge or 90 days, whichever is first.

The trial was placed on hold after a data safety and monitoring board (DSMB) review noted possible harm from thiamine in the subgroup of patients with a lactate >5mmol/L at the time of study inclusion, with a similar pattern seen in a companion trial in out-of-hospital cardiac arrest (NCT03450707). While the option of continuing to enroll patients with lactate ≤ 5mmol/L was provided, the trial was terminated formally in August 2022 due to lack of feasibility.