Intra-breath arterial oxygen oscillations detected by a fast oxygen sensor in an animal model of acute respiratory distress syndrome.

Background There is considerable interest in oxygen partial pressure ( P o 2 ) monitoring in physiology, and in tracking P o 2 changes dynamically when it varies rapidly. For example, arterial P o 2 ( P a O 2 ) can vary within the respiratory cycle in cyclical atelectasis (CA), where P a O 2 is thought to increase and decrease during inspiration and expiration, respectively. A sensor that detects these P a O 2 oscillations could become a useful diagnostic tool of CA during acute respiratory distress syndrome (ARDS). Methods We developed a fibreoptic P o 2 sensor ( P o 2 continuously in blood. By altering the inspired fraction of oxygen ( F I O 2 ) from 21 to 100% in four healthy animal models, we determined the linearity of the sensor's signal over a wide range of P a O 2 values in vivo . We also hypothesized that the sensor could measure rapid intra-breath P a O 2 oscillations in a large animal model of ARDS. Results In the healthy animal models, P a O 2 responses to changes in F I O 2 were in agreement with conventional intermittent blood-gas analysis ( n =39) for a wide range of P a O 2 values, from 10 to 73 kPa. In the animal lavage model of CA, the sensor detected P a O 2 oscillations, also at clinically relevant P a O 2 levels close to 9 kPa. Conclusions We conclude that these fibreoptic P a O 2 sensors have the potential to become a diagnostic tool for CA in ARDS.