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Chalkias A, Laou E, Papagiannakis N, Varvarousi G, Ragias D, Koutsovasilis A, Makris D, Varvarousis D, Iacovidou N, Pantazopoulos I, Xanthos T: Determinants of venous return in steady-state physiology and asphyxia-induced circulatory shock and arrest: an experimental study. Intensive Care Med Exp 2022; 10: 13

September 19, 2022

Mean circulatory filling pressure (Pmcf ) provides information on stressed volume and is crucial for maintaining venous return. This study investigated the Pmcf and other determinants of venous return in dysrhythmic and asphyxial circu- latory shock and arrest.
Twenty Landrace/Large-White piglets were allocated into two groups of 10 animals each. In the dysrhythmic group, ventricular fibrillation was induced with a 9 V cadmium battery, while in the asphyxia group, cardiac arrest was induced by stopping and disconnecting the ventilator and clamping the tracheal tube at the end of exhala- tion. Mean circulatory filling pressure was calculated using the equilibrium mean right atrial pressure at 5–7.5 s after the onset of cardiac arrest and then every 10 s until 1 min post-arrest. Successful resuscitation was defined as return of spontaneous circulation (ROSC) with a MAP of at least 60 mmHg for a minimum of 5 min.
After the onset of asphyxia, a ΔPmca increase of 0.004 mmHg, 0.01 mmHg, and 1.26 mmHg was observed for each mmHg decrease in PaO2 , each mmHg increase in PaCO2, and each unit decrease in pH, respectively. Mean Pmcf value in the ven- tricular fibrillation and asphyxia group was 14.81 ± 0.5 mmHg and 16.04 ± 0.6 mmHg (p < 0.001) and decreased by 0.031 mmHg and 0.013 mmHg (p < 0.001), respectively, for every additional second passing after the onset of cardiac arrest. With the exception of the 5–7.5 s time interval, post-cardiac arrest right atrial pressure was significantly higher in the asphyxia group. Mean circulatory filling pressure at 5 to 7.5 s after cardiac arrest predicted ROSC in both groups, with a cut-off value of 16 mmHg (AUC = 0.905, p < 0.001). Conclusion:
Mean circulatory filling pressure was higher in hypoxic hypercapnic conditions and decreased at a lower rate after cardiac arrest compared to normoxemic and normocapnic state. A Pmcf cut-off point of 16 mmHg at 5–7.5 s after cardiac arrest can highly predict ROSC.
Mean circulatory filling pressure, Venous return, Vascular capacitance hemodynamics, Shock, Resuscitation, Cardiac arrest, Hypoxemia, Hypercapnia