info:eu-repo/semantics/article
Influence Of The Surrounding Structures On The Parallel Volume Determination By Conductance Catheter
Fecha
2001-12Registro en:
Herrera de Olivera, Myriam Cristina; Olivera, Juan Manuel; Martínez, Roberto Javier; Ruiz, Estela del Valle; Valentinuzzi, Máximo Eugenio; Influence Of The Surrounding Structures On The Parallel Volume Determination By Conductance Catheter; Springer; Cardiovascular Engineering - (Print); 1; 3; 12-2001; 117-125
1567-8822
1432-9077
CONICET Digital
CONICET
Autor
Herrera de Olivera, Myriam Cristina
Olivera, Juan Manuel
Martínez, Roberto Javier
Ruiz, Estela del Valle
Valentinuzzi, Máximo Eugenio
Resumen
When left ventricular blood volume is evaluated by the conductance catheter technique, an important fraction of the injected current “leaks” into the surrounding tissues giving rise to a parallel volume (Vp). To study the influence of the thoracic structures on Vp, 5 anesthetized dogs were studied during (a) closed thorax, (b) open thorax, (c) reclosed thorax without pericardium, (d) open thorax without pericardium, (e) replacing the pericardium with a nonconducting bag. Intraventricular volume and pressure, surface ECG, and Vp (determined by saline dilution technique) were monitored during each condition. A conductance diagram was used to represent the behavior of the structures within the thoracic cage, including cardiac muscle, pericardium, and also other structures (OS) such as lung, skeletal muscle, and bone tissues. Under conditions (a) and (b), Vp was not significantly different (p < 0:005); thus, changes in OS did not
much modify Vp. When the pericardium was removed, the average Vp values for conditions (c) and (d) were smaller than those for (a) and (b) (p < 0:005). Apparently, because of good conductivity, the pericardium would favor the passage of current. Finally, when the fifth condition (e) was compared
with (a) or (b), the differences were highly significant (p < 0:005), while the differences between (e) and either (c) or (d) were less significant and more variable (p < 0:05). Duncan’s multiple comparisons by pairs confirmed the previous statements. The relative fraction of the total measured volume through the surrounding tissues (p%) systematically decreased as we moved from condition (a) to (e). Condition (e) decidedly forced a concentration of current lines through the myocardium. In conclusion, the pericardium is responsible for a significant fraction of the loss, which should be separated out from that due to the myocardium and OS. The latter would contribute to Vp with not more than about 10%.