Non-invasive intraoperative monitoring of blood pressure and arterial pCO2 during surgical anesthesia in mice.

Despite the constantly increasing use of genetically engineered mice in biomedical research, control of crucial physiological parameters such as blood pressure and arterial blood gases is difficult to achieve in temporarily anesthetized mice due to lack of techniques for reversible arterial cannulation. Here we report that arterial blood pressure and blood gases can be measured reliably in anaesthetized and artificially ventilated mice using non-invasive technology. C57Bl6 mice were anaesthetized by i.p. injection of midazolam, fentanyl, and medetomidin, intubated, and ventilated for 3h. End tidal pCO2 was monitored by micro-capnometry. Arterial blood pressure was measured non-invasively using a tail cuff. Non-invasive blood pressure (NIBP) correlated strongly with the invasive arterial blood pressure measured at the external carotid artery (r = 0.99, P < 0.001) and end tidal pCO2 values correlated very well with arterial blood pCO2 (r = 0.93, P < 0.001). The current results demonstrate that it is possible to reliably measure and control the most relevant physiological parameters in anesthetized mice. Thereby the current study may help to reduce animal numbers and perform mice experiments under more defined and controlled physiological conditions in the future.