The respiratory-gated image acquisition can partly eliminate problematic effects of the SPECT images obtained during non-breath-hold. display of xenon-133 (133Xe) gas SPECT data, and new analytical approaches by means of fractal analysis or the coefficient of variations of the pixel counts for Technegas SPECT data.
#Diagnostic ventilation cenon registration
11,12Hypotension, as remarked by the authors in both publications, may be caused by the “nature” of CPB.This paper describes the recent advances in technical and analytical methods in pulmonary ventilation SPECT studies, including a respiratory-gated image acquisition of Technetium-99m (99mTc)-labeled Technegas SPECT, a fusion image between Technegas SPECT and chest CT images created by a fully automatic image registration algorithm, and a three-dimensional (3D). Maintaining adequate blood pressure is one method to prevent neurologic damage during CPB and especially in cerebral embolism. 8–10In addition, low arterial blood pressures impair collateral perfusion of ischemic areas. Other investigators have described other external factors that can influence blood pressure: Low temperatures or elevated hydrostatic pressures (mean arterial pressure, intracranial pressure) can decrease bubble size, high flow velocities can destroy bubbles and lead to “foaming” effects, and low blood velocities can lead bubbles to form large entities. Instead, “air bubbles” were injected into carotid arteries, and the authors speculated that these occluded cerebral vessels.ĭifferences in outcomes were found only between groups with different mean arterial blood pressures during CPB. The authors only state that, “Hypotension is caused by the nature of CPB.” Can it therefore be asked whether the titles of both papers are slightly misleading in assuming that “cerebral air emboli” have caused any negative outcomes in rats? Cerebral air embolism is an event that was not investigated in the animals. Duration of hypotensive phases was not given in any group. Differences were found in neurologic outcomes comparing xenon to nitrogen animals submitted to CPB treatment. Sham animals during the same phase had mean arterial pressures between 127 ± 13 and 129 ± 17 mmHg during the same phases. In the authors’ earlier paper, 2the lowest blood pressures occurred during the first 45 min of CPB in the xenon groups, 71 ± 15 mmHg versus 88 ± 22 in the CPB nitrogen animals, and the values were 76 ± 11 mmHg in the xenon group versus 75 ± 14 mmHg in the nitrogen group at 90 min, the end of CPB. It therefore cannot be excluded that this selection process was influenced by bias that makes all results questionable. In addition, euthanasia is carried out in animals showing clear signs of neurologic damage, e.g. , not being able to eat or drink.”*†It is described in Anesthesiology that “after CPB all neurologic, cognitive, and behavioral test procedures were performed by an investigator, blinded for the treatment.” It is not mentioned that prior to those test procedures an unknown number of animals presenting “severe neurologic dysfunctions” such as “not having recovered from anesthesia until 3 hours after CPB” were killed by the (unblinded) main investigators. Animals exhibiting severe neurologic damage also are sacrificed during the first postoperative hours. “After CPB, animals demonstrating severe neurologic dysfunction were killed.” 2*†“Animals not recovering from anesthesia after 3 h are subjected to brain death diagnostic and exsanguinated in deep isoflurane anesthesia.