A novel technique to follow fast PaO2 variations during experimental CPR

Abstract Objective: An ultrafast responding fluorescent-quenching PO 2 probe allows time-resolved, in vivo measurement of PO 2 . This study describes several validation experiments of this new device in vitro, and reports its first use during cardiopulmonary resuscitation in an animal model of cardiac arrest. Methods: The influence of CO 2 , temperature and motion artefacts on the signal response of the PO 2 probe was analysed in vitro by systematic variation of these values. Thereafter, with approval of the Review Board for the care and use of animals, CPR was performed in four pigs. The PaO 2 course was recorded continuously at time resolution of Results: In vitro experiments showed that signal intensity is dependent on CO 2 concentration (ΔP fa O 2  = 4 mmHg/vol.% CO 2 ) and temperature (ΔP fa O 2  = 16 mmHg/°C), but it is robust with regards to probe motion. In the animal experiments, the uncoated fluorescence-quenching probe was calibrated by repeated simultaneous measurements with the Paratrend 7 ® sensor to correct the P fa O 2 for a potential signal drift, PCO 2 and temperature variations. In all animal experiments, the individual PaO 2 courses were clearly related to therapeutic interventions and their haemodynamic effects during CPR and allowed recording of ultrafast PO 2 changes with a time resolution of 80 ms. Conclusions: The results demonstrate the feasibility of ultrafast PO 2 measurement during CPR and low-flow states. They also demonstrate very rapid systemic effects of CPR upon aortic PO 2 . Among many other useful applications, the information derived from this technique may help to define the optimum conditions for successful defibrillation and restoration of spontaneous circulation.