| Abstract: | Tokics, Leif, Göran Hedenstierna, Leif Svensson, BoBrismar, Torsten Cederlund, Hans Lundquist, and ÅkeStrandberg.  / distributionand correlation to atelectasis in anesthetized paralyzed humans.J. Appl. Physiol. 81(4):1822-1833, 1996. Regional ventilation and perfusion were studiedin 10 anesthetized paralyzed supine patients by single-photon emissioncomputerized tomography. Atelectasis was estimated from twotransaxial computerized tomography scans. The ventilation-perfusion(/) distribution was alsoevaluated by multiple inert gas elimination. While the patients wereawake, inert gas / ratio wasnormal, and shunt did not exceed 1% in any patient. Computerizedtomography showed no atelectasis. During anesthesia, shunt ranged from0.4 to 12.2%. Nine patients displayed atelectasis (0.6-7.2% ofthe intrathoracic area), and shunt correlated with the atelectasis(r = 0.91, P < 0.001). Shunt was located independent lung regions corresponding to the atelectatic area. There wasconsiderable / mismatch, withventilation mainly of ventral lung regions and perfusion of dorsalregions. Little perfusion was seen in the most ventral parts (zone 1)of caudal (diaphragmatic) lung regions. In summary, shunt during anesthesia is due to atelectasis in dependent lung regions. The / distributions differ fromthose shown earlier in awake subjects. |
