Effect of increased cardiac output on pseudo-steady state exhaled ciprofol concentrations in a beagle model

Online breath analysis provides a non-invasive method for monitoring drug concentrations. Ciprofol, a novel intravenous anesthetic, shows potential for real-time monitoring. However, the impact of changes in cardiac output (CO) on ciprofol concentration in exhaled breath (Ce-cipro) remains unclear. This study aims to evaluate the effect of CO changes on Ce-cipro monitoring during anesthesia. Eight beagles were randomly divided into the ciprofol group (Group Cipro,n= 4) or the ciprofol + dobutamine group (Group Cipro + Dobu,n= 4). Ciprofol was intravenously infused at a rate of 0.125 mg kg^-1h^-1for 1 h. In the Cipro + Dobu group, dobutamine was administered at 35 min to increase CO. Ce-cipro was continuously monitored using the vacuum ultraviolet and time-of-flight mass spectrometry (VUV-TOF MS). CO was monitored at 0, 30, and 50 min using Doppler ultrasound. Mean arterial pressure (MAP) was maintained within ±20% of baseline between 40 and 50 min by adjusting the dobutamine infusion rate. The results indicated that in both groups, Ce-cipro levels gradually increased and reached a pseudo-steady state at around 30 min. However, no significant difference in Ce-cipro was observed in the Cipro + Dobu group between the 35-40 min (178.13 ± 71.67 pptv) and 50-55 min (181.89 ± 77.07 pptv) intervals (P= 0.05). This study suggests that when MAP is maintained within ±20% of preoperative levels, changes in CO do not significantly affect Ce-cipro monitoring. This finding provides valuable evidence supporting the application of online Ce-cipro monitoring in clinical anesthesia.