Effects of the chest wall and air volume on the perivascular pressure of the arterial segment. Study of the isolated canine lobule
Lupi-Herrera, E.; Furuya, M.E.; Quesada, A.; Leal, M.E.; Sandoval, J.; Correa, E.
Archivos del Instituto de Cardiologia de Mexico 59(6): 551-556
1989
ISSN/ISBN: 0020-3785 PMID: 2624500 Document Number: 332037
Ten isolated in situ canine left lower lobes (LLL) were studied in West zone II condition. In four dogs (group I) the chest wall surrounding the LLL was surgically removed, in the remaining dogs (group II) this procedure was not done. After basal parameters were obtained, minimal critical pressure (MCCP) was recorded and the influence of increasing alveolar pressure (PA) from o to 20 mmHg was noted. For group I lobes, PA value did not influence MCCP measurements, thus an independent relation between the pressures was found (delta MCCP/delta PA = 0). For group II lobes, when PA less than 6.8 +/- 2.1 mmHg also a delta MCCP/delta PA +/- was noted. Above this PA (PA1) a slope of 0.25 +/- 0.04 was documented for the delta MCCP/delta PA relationship. On the basis of our findings we conclude that MCCP is independent form PA. However if this relationship is studied in the isolated in situ LLL, at open chest with the condition of integrity of the chest wall when PA1 is applied the changes in MCCP are the result of the effect of lung inflation on the chest wall resulting in changes of the extravascular compliance (of the arterial segment) and is not due to a direct influence of PA on MCCP.