Use of a Central Venous Line for Fluids, Drugs and Nutrient Administration in a Mouse Model of Critical Illness

Summary

This protocol describes a centrally catheterized mouse model of prolonged critical illness. We combine the cecal ligation and puncture method to induce sepsis with the use of a central venous line for fluids, drugs and nutrient administration to mimic the human clinical setting.

Abstract

This protocol describes a centrally catheterized mouse model of prolonged critical illness. We combine the cecal ligation and puncture method to induce sepsis with the use of a central venous line for fluids, drugs and nutrient administration to mimic the human clinical setting. Critically ill patients require intensive medical support in order to survive. While the majority of patients will recover within a few days, about a quarter of the patients need prolonged intensive care and are at high risk of dying from non-resolving multiple organ failure. Furthermore, the prolonged phase of critical illness is hallmarked by profound muscle weakness, and endocrine and metabolic changes, of which the pathogenesis is currently incompletely understood. The most widely used animal model in critical care research is the cecal ligation and puncture model to induce sepsis. This is a very reproducible model, with acute inflammatory and hemodynamic changes similar to human sepsis, which is designed to study the acute phase of critical illness. However, this model is hallmarked by a high lethality, which is different from the clinical human situation, and is not developed to study the prolonged phase of critical illness. Therefore, we adapted the technique by placing a central venous catheter in the jugular vein allowing us to administer clinically relevant supportive care, to better mimic the human clinical situation of critical illness. This mouse model requires an extensive surgical procedure and daily intensive care of the animals, but it results in a relevant model of the acute and prolonged phase of critical illness.

Introduction

Critical illness is a disease state in which the function of one or more organ systems is hampered to the extent that the patient will die, unless intensive medical support is administered. Whereas the initial cause for admission to the intensive care unit (ICU) can vary, ranging from trauma, complicated surgery, burns, disease exacerbations to sepsis, all critically ill patients suffer from cellular damage, caused by hypoperfusion, hypoxia and excessive inflammation among others, which leads to organ failure. Most patients survive their acute insult, but an important fraction of the patients do not immediately recover and need prolonged intensive care. They are at hi....

Protocol

The protocol was approved by the University of Leuven Ethical Review Board for Animal Research.

1. Preparation of the Venous Line

1. Prepare the tip of the venous catheter by quickly immersing the middle part of 60 cm microrenathane (MRE) tubing in hot (> 220 °C) sesame oil. Subsequently stretch the middle part of the tube to produce a narrow diameter (outer diameter (OD) < 0.5 mm) by gently moving the ends of the tubing away from each other.
2. Use a scalpel blade to cut the tubing into two parts of 30 cm each (see Figure 1, Table 1).
3. Connect the MRE tubing to polyethylene tubing ....

Results

C57BL/6 mice were made critically ill as described above. We performed two experiments to assess post-CLP survival until two time points: survival until day 5 (n = 15) and survival until day 7 (n = 22) post-CLP. Survival curves of the two experiments were not significantly different (compared until day 5), indicating the reproducibility of the experimental setup. Non–surviving animals were found death or euthanized due to reaching human endpoints.  Ligation of 50% of the cecum in combinat.......

Discussion

We developed a more clinically relevant mouse model of critical illness, by combining the cecal ligation and puncture method to induce sepsis with the use of a central venous line for fluids, drugs and nutrient administration. This experimental setup is reproducible, allows to study the prolonged phase of critical illness and results in a stable mortality rate, hereby mimicking the human clinical situation¹.

Cecal ligation and puncture has been extensively recognized as.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Buprenorphine	Ecuphar		Vetergesic 0.3 mg/mL
C57BL/6	Janvier labs	C57BL/6JRj
colloids	Fresenius Kabi		Volulyte 6%
crystalloids	Baxter		Plasmalyte a viaflo
Ethilon 3.0	Ethicon	F3211
Imipenem	MSD		Tienam 500 mg powder for injection fluid
Isoflurane	Eurovet		Iso-vet
Ketamine	Eurovet		Nimatek 100 mg/mL
LocTite Super glue3 all plastics	Rectavit	119818
Mersilk 3.0	Ethicon	L192
Mersilk 5.0	Ethicon	F682
Microrenathane .025" O.D. x .012" I.D.	Bioseb	MRE-025
olimel N7E	Baxter
PE10 - Polyethylene .011" x .024"	Instech Solomon	BTPE-10
PE-50 tubing .023" x.038"	Instech Solomon	BTPE-50
Rodent Swivel 20 G	Bioseb	RS-20G
Ropivacaïne	Astrazenica		Naropin 2 mg/mL
Xylazine	VMD		Xylazine hydrochloride 2%