Static filling pressure in patients during induced ventricular fibrillation

Abstract

The static pressure resulting after the cessation of flow is thought to reflect the filling of the cardiovascular system. In the past, static filling pressures or mean circulatory filling pressures have only been reported in experimental animals and in human corpses, respectively. We investigated arterial and central venous pressures in supine, anesthetized humans with longer fibrillation/defibrillation sequences (FDSs) during cardioverter/defibrillator implantation. In 82 patients, the average number of FDSs was 4 +/- 2 (mean +/- SD), and their duration was 13 +/- 2 s. In a total of 323 FDSs, arterial blood pressure decreased with a time constant of 2.9 +/- 1.0 s from 77.5 +/- 34.4 to 24.2 +/- 5.3 mmHg. Central venous pressure increased with a time constant of 3.6 +/- 1.3 s from 7.5 +/- 5.2 to 11.0 +/- 5.4 mmHg (36 points, 141 FDS). The average arteriocentral venous blood pressure difference remained at 13.2 +/- 6.2 mmHg. Although it slowly decreased, the pressure difference persisted even with FDSs lasting 20 s. Lack of true equilibrium pressure could possibly be due to a waterfall mechanism. However, waterfalls were identified neither between the left ventricle and large arteries nor at the level of the diaphragm in supine patients. We therefore suggest that static filling pressures/mean circulatory pressures can only be directly assessed if the time after termination of cardiac pumping is adequate, i.e., >20 s. For humans, such times are beyond ethical options.

Value and determinants of the mean systemic filling pressure in critically ill patients

“…The only study that previously measured the value of Pmsf in humans was done in 82 patients in a completely different context of induced ventricular fibrillation for cardioverterdefibrillator implantation (22). However, recording was done after only 20 s of ventricular fibrillation, so that the equilibrium between arterial pressure (24.2 Ϯ 5.3 mmHg) and CVP (11.0 Ϯ 5.4 mmHg) was not achieved (22).…”

“…However, recording was done after only 20 s of ventricular fibrillation, so that the equilibrium between arterial pressure (24.2 Ϯ 5.3 mmHg) and CVP (11.0 Ϯ 5.4 mmHg) was not achieved (22). In our study, arterial venous pressure and CVP had reached equilibrium at the time of measurement in all cases, and no difference was found for 1-min Pmsf in the few patients with only an arterial or a central venous catheter.…”

“…This is due to the complexity of this parameter and the difficulty in practice of extrapolating Pmsf in heart-beating patients. Pmsf has only been measured in humans during electrophysiological explorations inducing cardiac arrest (22). Numerous methods based on heart-lung interactions in ventilated heart-beating animals were initially proposed for indirect determination of Pmsf by plotting the venous return curve (3,7,24), and the same indirect method was also proposed in ventilated patients in the ICU (13,14).…”

Influence of an Asymptotic Pressure Level on the Windkessel Models of the Arterial System

“…The concept of a static blood pressure level that is reached after termination of cardiac beating is nothing new (Schipke et al, 2003). Different attempts have been made to measure it during episodes of controlled cardiac arrest and mean values in the range of 10 mmHg (Schipke et al, 2003;Jellinek et al, 2000) were obtained.…”

“…Different attempts have been made to measure it during episodes of controlled cardiac arrest and mean values in the range of 10 mmHg (Schipke et al, 2003;Jellinek et al, 2000) were obtained. Another approach is to set P ∞ equal to right atrial pressure ≈ 3.2 mmHg, which was done by Aguado-Sierra et al (2008) in a simulation study.…”