Different injection techniques in the assessment of central haemodynamics in patients with cirrhosis

Abstract

Objective. Patients with cirrhosis often present with an abnormal distribution of blood volume with a reduced central blood volume (CBV) and central circulation time (CCT). In this group of patients it is important to determine the central haemodynamics as accurately as possible. The purpose of the present study was to compare an alternative injection technique by injecting technetium-labelled human serum albumin (^99mTc-HSA) from a deposit within the catheter lumen with the conventional injection technique by injecting iodine-labelled human serum albumin (¹²⁵I-HSA) directly from a syringe. Materials and methods. In 192 patients with cirrhosis, CCT, CBV, and cardiac output (CO) were determined according to kinetic principles. Injection of the two radiolabelled HSA were performed simultaneously and followed by arterial blood sampling every second for the first minute. Results. CCT was significantly shorter, and CO and CBV were significantly lower when determined by the alternative catheter deposit injection technique compared to determination by the traditional syringe deposit injection technique. The mean difference (bias) between CCT measured with the two methods was 0.38 s with limits of agreement ranging from − 0.83 s to 1.59 s. Conclusion. This study demonstrates that different injection techniques result in a minor but significant difference of the measured haemodynamics. When highly accurate measurements of the central haemodynamics are needed, we recommend using the alternative injection technique by injection of the indicator from a deposit within the catheter in order to reduce overestimation of CCT.

Key Words::

• Blood volume
• cardiac output
• haemodynamics
• indicator dilution technique
• kinetics
• radioisotope dilution technique

Acknowledgements

The authors wish to thank the technicians at Department of Clinical Physiology, Hvidovre Hospital for diligently and skillful assistance.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

Funding sources: The study was supported by grants from the NovoNordisk Foundation.