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Gas Exchange in the Lungs
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The ratio of the shunt flow to the total blood flow from the left ventricle (the cardiac output) can be calculated by considering the different oxygen contents of shunted, pulmonary end-capillary and arterial blood. The basis for the shunt equation is that the oxygen carried by the cardiac output (arterial blood) must be the sum of the oxygen carried in the pulmonary end-capillary blood flow and the oxygen in the shunt blood flow. The assumption made is that shunted blood has the same oxygen content as mixed venous blood, although, for example, bronchial and thebesian venous blood oxygen contents may be different:
Respiration
Published in Sarah Armstrong, Barry Clifton, Lionel Davis, Primary FRCA in a Box, 2019
Sarah Armstrong, Barry Clifton, Lionel Davis
The shunt equation is used to calculate the percentage of shunted blood in the lung. It is an application of the Fick principleIt uses a two compartment model where Ideal – perfect V/Q matching and ideal gas exchange. Sats assumed to be 100%Shunt – pulmonary capillaries have no exposure to the alveoliThe total content of oxygen leaving the lungs is equal to the cardiac output (QT) multiplied by the arterial oxygen content (CaO2)It is also equal to the shunt flow (QS) multiplied by the mixed venous oxygen content (CvO2) (assuming no oxygen is taken up or given to shunted blood by the lungs) plus flow to ventilated alveoli multiplied by pulmonary capillary oxygen content (CcO2)
Mismatch and Shunt
Published in Lara Wijayasiri, Kate McCombe, Paul Hatton, David Bogod, The Primary FRCA Structured Oral Examination Study Guide 1, 2017
Lara Wijayasiri, Kate McCombe, Paul Hatton, David Bogod
The shunt equation allows the amount of shunt caused by the addition of venous blood to the arterial circulation to be calculated. It requires the subject to be breathing 100% oxygen. Of fundamental importance is the fact that of all of the causes of hypoxia, shunt cannot be corrected by breathing 100% oxygen because the shunted blood bypasses ventilated alveoli and thus is never exposed to the higher alveolar PO2. The shunted blood therefore continues to depress the arterial oxygen content.
Does the antisecretory peptide AF-16 reduce lung oedema in experimental ARDS?
Published in Upsala Journal of Medical Sciences, 2019
Annelie Barrueta Tenhunen, Fabrizia Massaro, Hans Arne Hansson, Ricardo Feinstein, Anders Larsson, Anders Larsson, Gaetano Perchiazzi
A triple-lumen central venous catheter for fluid infusions and a pulmonary artery catheter (Edwards Life-Science, Irvine CA, USA) for measurement of cardiac output (CO) and pulmonary artery pressures were inserted via the right jugular vein. An arterial catheter was inserted in the right carotid artery for blood sampling and blood pressure measurement, and a pulse contour cardiac output (PiCCO) catheter (PV2015L20, Pulsion, Munich, Germany) was placed in the right femoral artery for estimation of EVLW evolution. Blood gases were analyzed on an ABL 3 analyzer (Radiometer, Copenhagen, Denmark) immediately after sampling, and venous admixture was calculated according to the shunt Equation (23). A midline mini-laparotomy was performed for catheterization of the urinary bladder for urine drainage.
Pulmonary hypoxia and venous admixture correlate linearly to the kinetic energy from porcine high velocity projectile behind armor blunt trauma
Published in Experimental Lung Research, 2021
Ulf P. Arborelius, David Rocksén, Jenny Gustavsson, Mattias Günther
Venous admixture (Q’s/Q’t) was calculated by the shunt equation (Berggren equation):122 = pulmonary end capillary O2 content, same as alveolar O2 content = SaO2 x Hb x 1.3. SaO2 was assumed at 100% in the lungs. CaO2 = arterial O2 content (SaO2 x Hb x 1.3), CvO2 = mixed venous O2 content (SvO2 x Hb x 1.3). V’A/Q’ = alveolar minute ventilation/cardiac output. Units: CcO2/CaO2/CvO2 = mL/L, Hb = g/L, SaO2 = %.
Severe, transient pulmonary ventilation-perfusion mismatch in the lung after porcine high velocity projectile behind armor blunt trauma
Published in Experimental Lung Research, 2020
David Rocksén, Ulf P. Arborelius, Jenny Gustavsson, Mattias Günther
Venous admixture (Qs/Qt) was calculated by the shunt equation (Berggren equation):142 = pulmonary end capillary O2 content, same as alveolar O2 content = SaO2 × Hb × 1.3. SaO2 is assumed at 100% in the lungs. CaO2 = arterial O2 content (SaO2 × Hb × 1.3), CvO2 = mixed venous O2 content (SvO2 × Hb × 1.3). V′A/Q′ = alveolar minute ventilation/cardiac output. Units: CcO2/CaO2/CvO2 = mL/L, Hb = g/L, SaO2 = %.