Relationship Between Arterial and Intraosseous Pressure in African Grey Parrots (Psittacus erithacus)

The aim of this study was to determine the relationship between arterial pressure and intraosseous (IO) pressure obtained by conventional IO needle in African grey parrots (Psittacus erithacus). Twelve healthy African grey parrots with mean body weight 465.25 g were anesthetized in an induction chamber with 5% isoflurane and 100% oxygen, followed by intubation and connection to a pressure-limited intermittent-flow ventilator. A 24-gauge catheter was placed into the deep radial artery in one wing and a 22-gauge needle was placed into the distal ulnar medullary cavity in the contralateral wing. Both cannulas were connected to a 9-cm noncompliant tube and then linked to a disposable pressure sensor. Pressures and waveforms from both cannulas were recorded for 10 minutes while isoflurane was maintained at 3%. The results showed that the arterial pressure values were normally distributed (P < .05), whereas the IO pressure values were not (P > .05). Arterial and IO pressure were not correlated (P > 0.05), but IO pressure and heart rate were positively correlated (Spearman's rank correlation coefficient, 0.58; P < .05). Multiple characteristics of the IO waveforms were observed, including distinguishable continuous waveforms (n = 8), a single wave crest (n = 4), respiratory variation (n = 7), and a dicrotic notch (n = 3), and IO waveforms were appearing at a similar or delayed point relative to the related arterial waveforms (n = 8). Although IO pressure was not correlated with arterial pressure in the African grey parrots under the study conditions, the positive correlation between IO pressure and heart rate and the IO waveform characteristics suggest that the inflow arterioles likely account for the retained arterial waveform radiating into the IO space. These findings are consistent with those from all previously tested mammals. Therefore, insights into potential future improvements of the measuring techniques and protocols can be reached by thoroughly reviewing the current knowledge on IO pressure in mammals.