OBJECTIVESince 2011 EB-APS conference, we hypotheses that phase switching of inspiration-expiration is dominantly initiated by oscillatory information PaO2, PaCO2 and [H+] via fast peripheral chemical receptors. However, the evidence of the waveform of ABG is lack.

METHODSSix surgery patients with normal heart function and negative Allen test, had been placed the arterial catheterization directly connected to 3 x 1 000 mm pre-heparin plastic pipe for continuous collecting arterial blood. We counted the number of heart beat for the blood collecting time, and separated the blood pipe into the heart beat numbers' short pieces using haemostatic forceps, then put pipe into iced water at once fir analyzing PaO2, PaCO2, pH and SaO2 as soon as possible. We selected two breaths cycles of waveform from each patient for data calculations of magnitudes and time interval.

RESULTSThe heart beat numbers for filling blood into pipe were 16 ± 2, and all covered more than 2 breathing cycles. Each breathing cycle is cover 5 ± 0.6 heart beat. There were significant changes of PaO2, PaCO2, [H+] a and SaO2 (i.e. the highest high values compare to the next lowest values, P < 0.05). The time interval of changing PaO2, PaCO2, [H+]a and SaO2 magnitudes were 11.28 ± 1.13 mmHg, 1.77 ± 0.89 mmHg, 1.14 ± 0.35 nmol/L and 0.52% ± 0.44% respectively.

CONCLUSIONThis simple continuous beat-by-beat arterial blood sampling and ABG analyzing method is new and practicable. We obtain a clear evidence of periodic parameters ABG waveform, which following breathing cycle.