Oxygen inhalation improves postoperative survival in ketamine-xylazine anaesthetised rats: An observational study

Autoři: Mare Mechelinck aff001;  Carolin Kupp aff001;  Johanne C. Krüger aff002;  Moriz A. Habigt aff001;  Marius J. Helmedag aff003;  René H. Tolba aff002;  Rolf Rossaint aff001;  Marc Hein aff001
Působiště autorů: Department of Anaesthesiology, Uniklinik RWTH Aachen, Aachen, Germany aff001;  Institute for Laboratory Animal Science and Experimental Surgery, Uniklinik RWTH Aachen, Aachen, Germany aff002;  Department of General, Visceral and Transplantation Surgery, Uniklinik RWTH Aachen, Aachen, Germany aff003
Vyšlo v časopise: PLoS ONE 14(12)
Kategorie: Research Article
doi: https://doi.org/10.1371/journal.pone.0226430



A simple but reliable and safe anaesthetic procedure is required for surgical interventions in small rodents. Combined ketamine and xylazine injections are often used in rats for less invasive surgery, possibly with spontaneous breathing and without airway management. However, there are important pitfalls to be avoided by special precautions and monitoring, as shown subsequently.

Study design

Observational study.


Twenty-four anaesthetic procedures for bile duct ligation, sham operation or carotid artery dilatation in 20 male Sprague-Dawley rats, preoperatively weighing between 440 and 550 g.


Intolerable high mortality rates occurred in the first 7 postoperative days while establishing a new experimental model in rats using ketamine-xylazine anaesthesia. Rats were spontaneously breathing ambient air during the first 12 surgeries without airway management. An observed high mortality rate in these animals led to a change in the trial protocol: the insufflation of 2 litres of oxygen per minute via nose cone during the following 12 rat surgeries. Retrospective comparison of the outcome (without oxygen vs. with oxygen insufflation) was conducted.


The perioperative mortality rate could be significantly reduced from 58% (7/12) to 17% (2/12) (p = 0.036) by oxygen insufflation via nose cone. Significantly different levels of intraoperative oxygen saturation (SpO2; 89 ± 4% [without oxygen] vs. 97 ± 0.5% [with oxygen], p < 0.0001), but no significant differences in heart rate (HR; 267 ± 7 beats minute–1 [bpm] [without oxygen] vs. 266 ± 6 bpm [with oxygen], p = 0.955) were observed.

Conclusions and clinical relevance

In summary, rats under ketamine-xylazine anaesthesia are susceptible to hypoxia. This may lead to increased delayed mortality related to hypoxia induced lung failure. Apparently, this is an underestimated problem. We highly recommend using additional oxygen insufflation in spontaneously breathing rats under ketamine-xylazine anaesthesia with basic monitoring such as measurement of oxygen saturation.

Klíčová slova:

Anesthesia – Breathing – Death rates – Medical hypoxia – Oxygen – Surgical and invasive medical procedures – Vascular surgery – Bile ducts


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2019 Číslo 12
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