# An Exploratory Randomized Controlled Trial of 0.9% Saline Versus Lactated Ringer's Solution on Intraoperative Metabolism Among Patients Undergoing Lumbar Spinal Surgery

## TL;DR

This study compares two intravenous fluids during spinal surgery and finds that lactated Ringer's solution leads to better metabolic outcomes than 0.9% saline.

## Contribution

The study provides new evidence on the metabolic effects of lactated Ringer's versus 0.9% saline during lumbar spinal surgery.

## Key findings

- Lactated Ringer's solution was associated with favorable plasma metabolism and less gluconeogenesis.
- 0.9% saline caused hyperchloremic acidosis and higher norepinephrine use.
- Metabolic changes included altered concentrations of cortisol, oxaloacetate, and leucine metabolites.

## Abstract

Intravenous crystalloid fluid infusion is a mandatory nutritional intervention received by surgical patients. Crystalloids vary in the pH value and electrolyte balance when administered; these effects directly alter plasma and urine compositions and can considerably affect the patient's intraoperative metabolism.

This randomized controlled study compared 0.9% saline solution and lactated Ringer's solution in terms of intraoperative metabolism among 56 patients undergoing lumbar spinal surgery. Blood and urine samples were obtained before and after surgery for arterial blood gas analysis and untargeted metabolomic analysis using liquid chromatography-mass spectrometry.

Patients receiving 0.9% saline developed hyperchloremic acidosis and exhibited higher postoperative plasma concentrations of sodium (interaction P = 0.008) and glucose (interaction P = 0.034). They also required higher intraoperative norepinephrine doses (18 [0-43] μg vs. 0 [0-5] μg; P < 0.001) compared with patients who received lactated Ringer's solution. Significant intraoperative changes were noted in 27 plasma metabolites and 32 urinary metabolites related to stress responses and catabolic pathways. Patients receiving lactated Ringer's solution exhibited favorable metabolism in the blood. This was indicated by attenuated cortisol concentrations (interaction P = .051); significantly higher oxaloacetate concentrations (interaction P = .015), which may indicate less intraoperative gluconeogenesis (interaction P = .015); lower leucine degradation metabolite concentration, namely hydroxyisocaproic acid (interaction P = .055); and an attenuated decline in anti-inflammatory phospholipid breakdown metabolite, namely 15-ketoeicosatetraenoic acid (interaction P = .063). By contrast, patients receiving 0.9% saline solution exhibited unfavorable metabolism in urine indicated by reduced excretion of citric acid and creatine, which correlated with reduced glomerular filtration rates.

The administration of lactated Ringer's solution may facilitate more favorable intraoperative metabolic profiles than the administration of 0.9% saline solution during lumbar spinal surgery.