Targeted temperature management (TTM) is the primary strategy in post-resuscitation care for patients with cardiac arrest [[1], [2], [3]]. Current American Heart Association guidelines strongly recommends to maintain a constant target temperature in patients with out-of-hospital cardiac arrest (OHCA), regardless of the initial rhythm with moderate-quality evidence [2]. The major complications related to TTM include shivering and ventilator asynchrony [4]. In particular, shivering prevents achieving and stabilizing the target temperature and may cause secondary brain damage due to increased metabolic stress, heat production, and oxygen consumption [[5], [6], [7]]. When complications cannot be adequately controlled by sedatives and analgesics to maintain the targeted temperature, neuromuscular blocking agents (NMBAs) are often administered, as they effectively control shivering.

A recent systematic review based on observational studies found that NMBA use was associated with favorable neurological outcomes [8]. On the other hand, current guidelines recommend avoiding routine NMBA use during TTM and using NMBAs only in cases of uncontrollable severe shivering. Previous two small randomized controlled trials (RCT), focused on lactate clearance as primary outcome, found no significant effect of NMBAs during TTM for patients with OHCA [9,10]. In addition, NMBAs were reported to increase the risk of pneumonia and obscure the activity of convulsive seizures, thereby deteriorating the outcome of OHCA patients [11,12].

Taken together, the efficacy and the disadvantages of NMBAs during TTM are still debated, and more evidence still needs to be provided. The gaps in evidence between RCTs and observational studies may stem from small sample sizes or inadequate adjustment for confounding factors. We conducted the present study using a prospective registry of OHCA patients with rigorous adjustments and advanced propensity score analysis. Our hypothesis was that NMBA use during TTM benefits neurological outcomes by stabilizing TTM and controlling adverse complications such as shivering.