The Colon Ascendens Stent Peritonitis (CASP) is a highly standardized model for polymicrobial abdominal sepsis in rodents. This article describes the surgical procedure of CASP. The CASP model and its variants allow the systematic investigation of various problems concerning the subject of sepsis.
Sepsis remains a persistent problem on intensive care units all over the world. Understanding the complex mechanisms of sepsis is the precondition for establishing new therapeutic approaches in this field. Therefore, animal models are required that are able to closely mimic the human disease and also sufficiently deal with scientific questions. The Colon Ascendens Stent Peritonitis (CASP) is a highly standardized model for polymicrobial abdominal sepsis in rodents. In this model, a small stent is surgically inserted into the ascending colon of mice or rats leading to a continuous leakage of intestinal bacteria into the peritoneal cavity. The procedure results in peritonitis, systemic bacteraemia, organ infection by gut bacteria, and systemic but also local release of several pro- and anti-inflammatory cytokines. The lethality of CASP can be controlled by the diameter of the inserted stent. A variant of this model, the so-called CASP with intervention (CASPI), raises opportunity to remove the septic focus by a second operation according to common procedures in clinical practice. CASP is an easily learnable and highly reproducible model that closely mimics the clinical course of abdominal sepsis. It leads way to study on questions in several scientific fields e.g. immunology, infectiology, or surgery.
CASP is a polymicrobial model of abdominal sepsis that meets most criteria postulated for a valuable sepsis model: CASP can be performed in small animals, is highly reproducible, easily to monitor by standard parameters, provides good read out possibilities, and closely mimics clinical settings of abdominal sepsis. In a comparative study we could show that CASP leads to diffuse peritonitis with early and steadily increasing systemic infection and inflammation (systemic inflammatory response syndrome), whereas cecal ligation and puncture (CLP) reveals a model of intra-abdominal abscess formation with sustained and minor signs of systemic inflammation (1). The technique of CASPI presents a possibility to simulate the clinical course of peritonitis with consecutive surgical focus sanitation, which is the most important therapeutic principle in humans. CASP can be applied for all questions around sepsis or peritonitis and is therefore useful for all disciplines dealing with sepsis research, for example immunology, pharmacology, surgery, intensive care medicine, etc. A selection of publications concerning different subjects of sepsis using the CASP model is given below (1-14).
When starting with CASP, one should be aware that some practice is necessary to perform the operation exactly and quickly. Surgical experience may be helpful but is not required. We recommend detection of letality as a parameter for correct performance of CASP. One should start with 14G CASP as a large stent is easier to handle than a thinner one. A trained CASP surgeon is able to operate one mouse within 10 minutes. Before starting any experiments, you should make sure that you are near that period. When you gained some experience with the surgical procedure, you should conduct a survival kinetic to check your skills. 14G CASP should result in a 100% lethality. Beginners in our laboratory have to prove that they are able to generate a 100% lethality with 14G CASP before they start with experiments. Additionally, bacteriology and cytokine measurements should be performed to verify sepsis. If you have problems in the beginning with the microsurgical steps of CASP, the use of magnifying glasses or a surgical microscope may be helpful. But in principal, CASP can be well performed without these utilities. For reproduction of our survival rates, it is absolutely necessary that the same materials, especially the stents (BD Venflon, see below), are used. Otherwise, substantial variations of the results are possible. Additionally, we suggest that there can be variations of the results depending on, for example, the individuality of the surgeon. However, the influence of factors like that should be small.
In summary, CASP is a practicable, simple, reproducible and valuable sepsis model that mimics closely the clinical situation of abdominal sepsis. It is therefore suitable for all fields of sepsis research.
The authors have nothing to disclose.
The authors thank Nico Zantl, Klaus Pfeffer, and Bernhard Holzmann. This study was supported by the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg, Germany (GRK-840; Vo 450/10-1).
Material Name | Tipo | Company | Catalogue Number | Comment |
---|---|---|---|---|
Narcotic fluid | Mix 0.5 mL Rompun with 4.0 mL Ketanest, and add 5.5 mL of saline solution (0.9%). For complete anesthesia, inject intraperitoneally 10 μL/g body weight | |||
Rompun (20 mg/ml Xylazine) | Bayer AG 51368 Leverkusen, Germany | |||
Ketanest (25mg/ml Esketamine) | Pfizer Pharma GmbH, 10785 Berlin, Germany | 647028001E | ||
BD Venflon 18GA (1,2x45mm, 80ml/min) | BD Biosciences, Franklin Lakes, NJ USA 07417 | 391457 | ||
BD Venflon 16GA (1,7x45mm, 180ml/min) | BD Biosciences, Franklin Lakes, NJ USA 07417 | 391455 | ||
BD Venflon 14GA (2,0x45mm, 270ml/min) | BD Biosciences, Franklin Lakes, NJ USA 07417 | 391456 | ||
Catgut Polyester 4/0 white, non absorbable | Catgut GmbH, 08258 Markneukirchen, Germany | 17218113 | ||
Mariderm black 7/0, non absorbable | Catgut GmbH, 08258 Markneukirchen, Germany | 18104900 |