///2017 Abstract Details
2017 Abstract Details2019-08-02T15:54:53-06:00

Intravenous Fluid Flow Rates with the Addition of a Fluid Warming Insert: An In Vitro Study.

Abstract Number: T-39
Abstract Type: Original Research

John J Kowalczyk MD1 ; Mary Yurashevich MD, MPH2; Naola Austin MD3; Brendan Carvalho MBBS, FRCA4

Introduction: Intravenous fluid coloading decreases hypotension after spinal anesthesia (1). Fluid warming is recommended to reduce hypothermia during cesarean delivery (2). The increase in tubing length and resistance associated with in-line warming devices used to prevent perioperative hypothermia may reduce the speed of intravenous fluid administration, and therefore the efficacy of coloading. The aim of the study was to investigate the effect of a fluid warming system on flow rates.

Methods: We conducted a randomized in vitro study. The experimental groups included an unheated and heated 3M Ranger insert added to a standard intravenous set. These were compared to a control group consisting of the same intravenous set without warming insert. All sets were pressurized to 250 mmHg and connected to an 18 gauge intravenous catheter. The time (seconds) taken for 800 ml (10 ml/kg x 80 kg standard patient weight) of lactated ringers to collect into a graduated cylinder was measured. The experiment was repeated for a total of 16 times per group.

Results: The mean flow rates of the experimental and control groups are shown in Table 1. An 800 ml fluid bolus took 11 sec longer (95% CI 10 - 16, p=0.0003) to administer when a heated in-line warming device was added to a standard intravenous set (281 sec in the Heated Ranger versus 271 sec in the control group). The Heated Ranger decreased infusion time compared to the Unheated Ranger (Table 1).

Conclusions: The modest decrease in flow rates with an in-line fluid warming insert is unlikely to impact the ability to provide effective coloading or rapid fluid resuscitation. In-line warming devices may be used in cases with moderate volume fluid administration or high chance of blood administration to maintain normothermia without concern for decreased fluid flow rates.


1. Can J Anaesth. 2010 Jan;57(1):24-31.

2. Br J Anaesth. 2015 Oct;115(4):500-10.

SOAP 2017