Study Highlights Trends in ICU Mortality with Balanced Crystalloids

The choice between balanced crystalloids and saline for fluid resuscitation in critically ill patients has been a subject of ongoing debate, with uncertainties regarding their comparative effects on in-hospital mortality.

This systematic review and individual patient data meta-analysis aimed to provide a comprehensive assessment of whether the use of balanced solutions, as opposed to 0.9% sodium chloride (saline), influences in-hospital mortality among adult patients in intensive care units (ICUs). 

The study conducted a thorough search of PubMed, Embase, and CENTRAL databases, spanning from inception until March 1, 2022, with an update until September 1, 2023. The inclusion criteria comprised individually randomized and cluster-randomized trials that compared balanced solutions with saline for fluid resuscitation and maintenance fluids in adult ICU patients. Eligible trials administered the allocated fluid throughout the ICU admission or, for trials assessing landmark mortality, until the specified time point (if ≥28 days).

Authors of eligible trials were contacted for individual patient data, and Bayesian regression models were employed for centralized analysis. The primary outcome measure was in-hospital mortality, with prespecified subgroups, including patients with traumatic brain injury. 

From an initial pool of 5219 records, six eligible randomized controlled trials were identified. The analysis included data from 34,685 participants, with 17,407 assigned to receive balanced crystalloids and 17,278 to receive saline. The mean participant age was 58.8 years, with 42.1% females and 57.9% males. Among participants consenting to report in-hospital mortality, 16.8% assigned balanced solutions and 17.3% assigned saline died in the hospital.

The odds ratio (OR) for in-hospital mortality was 0.962 (95% credible interval [CrI] 0.909 to 1.019), indicating a small absolute difference of –0.4 percentage points (–1.5 to 0.2). The posterior probability that balanced solutions reduced mortality was 0.895. 

In the subgroup analysis of patients with traumatic brain injury, 19.1% assigned balanced solutions and 14.7% assigned saline died in the hospital, with an OR of 1.424 (95% CrI 1.100 to 1.818) and an absolute difference of 3.2 percentage points (0.7 to 8.7). The probability that balanced solutions increased mortality in traumatic brain injury patients was 0.975. An independent risk of bias assessment categorized two trials as low risk and four as high risk. 

The study suggests a high probability that using balanced solutions in the ICU is associated with a reduction in in-hospital mortality, though the certainty of evidence was moderate, and the absolute risk reduction was small. Notably, in patients with traumatic brain injury, the use of balanced solutions was linked to an increased risk of in-hospital mortality. These findings underscore the importance of considering patient subgroups when making fluid resuscitation decisions in critical care settings. 

Journal Reference  

Fernando G Zampieri et al, Balanced crystalloids versus saline for critically ill patients (BEST-Living): a systematic review and individual patient data meta-analysis, The Lancet Respiratory Medicine (2023). DOI: 10.1016/S2213-2600(23)00417-4.