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Table 4 Model Parameters of Gas Exchange Function

From: Using a human cardiovascular-respiratory model to characterize cardiac tamponade and pulsus paradoxus

Tissue Type Gas Exchange Parameter 15 ml effusion
(control)
1000 ml effusion
Lung PO 2 (mmHg) 123.4 122.0
  PCO 2 (mmHg) 33.9 32.4
  SO 2 (%) 98.9 99.0
  A-V O 2 concentration difference (%) -4.0 -6.3
  A-V CO 2 concentration difference (%) 3.9 7.1
Peripheral Tissue PO 2 (mmHg) 46.1 37.3
  PCO 2 (mmHg) 40.6 44.3
  SO 2 (%) 81.1 68.6
  A-V O 2 concentration difference (%) 3.7 6.2
  A-V CO 2 concentration difference (%) -4.5 -7.2
Brain PO 2 (mmHg) 35.4 35.4
  PCO 2 (mmHg) 43.2 41.5
  SO 2 (%) 65.5 66.2
  A-V O 2 concentration difference (%) 6.7 6.3
  A-V CO 2 concentration difference (%) -6.5 -5.8
  1. Model parameters indicating gas exchange function in lung, peripheral tissue, and brain. The breathing pattern is the pseudo-human respiratory waveform used in this study. With tamponade, peripheral tissue reflects effusion-induced oxygenation reduction with fall in O2 partial pressure (PO2), rise in CO2 partial pressure (PCO2), and reduced O2 percent saturation (SO2). There is little change in PO2, PCO2 and SO2 in the lung and brain. A-V O2/CO2 concentration difference measures the percent gas concentration difference in the arterio-venous (A-V) path. This O2 and CO2 concentration difference increases in lung and peripheral tissue with slower blood flow allowing more time for oxygen intake and increase in CO2. A-V differences remain largely unchanged in the brain due to the built-in autoregulation mechanism of the cerebral circuit. Using the pseudo-human respiratory waveform, control PO2 is higher and PCO2 is lower than previously reported model results [11] due to deeper inspiration and relatively longer expiration. SO2 is also slightly increased.