Radioaerosol ventilation imaging in ventilator-dependent XXXX . Technical considerations.

@entity1 @entity156 @entity1151
The differentiation of @entity1151 ( @entity1151 ) from regional ventilatory abnormalities accompanied by reduced perfusion requires contemporary perfusion and ventilation studies. Distinguishing these conditions in ventilator-dependent @entity1 is aided by administering a Tc-99m aerosol to characterize regional ventilation, and by performing a conventional Tc-99m MAA perfusion study. The technique uses a simple "in-house" constructed apparatus. Simple photographic techniques suffice, but computer subtraction of perfusion from the combined perfusion-ventilation image renders interpretation easier if aerosol administration follows perfusion imaging. @entity156 can be examined in a single study. Excluding normal or near-normal perfusion studies, @entity1151 was thought to be present in eight of 16 @entity1 after perfusion imaging alone, but in only one of eight after added aerosol imaging. Angiography confirmed the diagnosis in that @entity1 . Of the eight @entity1 who had abnormal perfusion but were thought unlikely to have @entity1151 from the perfusion study alone, two had normal ventilation, and subsequently were shown to have @entity1151 by angiography. Because angiography was only performed on @entity1 who were thought to have a high probability of @entity1151 on sequential perfusion-ventilation imaging, the true incidence of @entity1151 may have been higher. Aerosol ventilation imaging is a useful adjunct to perfusion imaging in @entity1 on ventilators. It requires an efficient delivery system, particularly if aerosol administration follows perfusion imaging, as it does in this study. The major disadvantage of aerosol imaging compared to a gas in intubated @entity1 is the significant bronchial deposition due to retained mucus secretions.(ABSTRACT TRUNCATED AT 250 WORDS)
