A systematic review and meta-analysis just published in Resuscitation Plus asked a question that sounds like it should have a clean answer by now: does volume therapy during or after cardiac arrest actually help? Fifty-eight articles, 14 randomized trials, 710,000 patients across observational studies. The short version: we still don't know.
What They Asked
The review separated the question into three phases — intra-arrest volume therapy, traumatic cardiac arrest, and post-ROSC resuscitation. Sensible framing. The physiology is different enough at each stage that lumping them together would obscure more than it revealed.
For non-traumatic intra-arrest scenarios, the trials that existed looked at hypertonic saline with hydroxyethyl starch (no longer in clinical use) and cold crystalloid infusion. Neither showed outcome benefit. For traumatic cardiac arrest, direct evidence was thin — a single subgroup analysis comparing blood products to crystalloid, no significant difference. Post-ROSC, trials of cold crystalloid and balanced versus unbalanced crystalloids showed nothing meaningful either.
What the Evidence Actually Tells Us
The honest finding is the absence of one: there are no randomized trials comparing volume therapy to no volume therapy during CPR. Every trial compared one fluid strategy to another. That's a fundamental gap. The question of whether to give fluid at all during arrest remains unanswered by the RCT literature.
Observational data — 710,000 patients worth — carries serious risk of bias in both directions. Sicker patients get more fluid. Patients who achieve ROSC get post-arrest care that confounds volume decisions. The GRADE certainty ratings here are low to very low across the board, which the authors state plainly.
Why It Matters Clinically
Volume during arrest is one of those decisions made reflexively in most resuscitations — a liter of saline goes up almost automatically while the team focuses on compressions and rhythm. This review doesn't say that's wrong. It says we haven't tested it rigorously enough to know. That's actually useful information, because it means current practice is running on physiologic rationale and habit rather than trial data.
For post-ROSC care, the balanced versus unbalanced crystalloid question is worth watching. The ICU literature on balanced solutions has been trending toward benefit in sepsis and critical illness. Whether that extends to post-cardiac arrest physiology — where the hemodynamic picture is dominated by myocardial stunning and systemic ischemia-reperfusion — is genuinely unknown and clinically relevant.
The Takeaway
This is the kind of paper that matters not because it changes what you do tonight, but because it clarifies how much of what you do tonight is not evidence-based in the way you might assume. Volume during arrest is reasonable. It is not proven. That distinction should inform how dogmatically you defend any particular strategy when the next trial comes out.