Can Passive Blood Redistribution to the Thorax Improve the Effectiveness of Cardiopulmonary Resuscitation? A Physiological Hypothesis Based on Frank-Starling’s Law View PDF

^*Mario Jorge Mc Loughlin
Medicine, Florida Medical Research Center, Buenos Aires, Argentina
Francisco Javier Mateu
Medicine, Florida Medical Research Center, Buenos Aires, Argentina

^*Corresponding Author:

Mario Jorge Mc Loughlin
Medicine, Florida Medical Research Center, Buenos Aires, Argentina

Published on: 2026-07-03

Abstract

During cardiopulmonary resuscitation (CPR), external chest compressions generate an artificial blood flow with limited efficacy. This work proposes that the passive redistribution of the blood volume from the lower extremities to the central axis - by the elevation of legs or devices such as the antishock (mast) trusses - would improve the ventricular filling in diastole and, therefore, would increase the systolic volume generated by each rib custody. This hypothesis relies on Frank- Starling’s law and basic hemodynamic principles. Although these maneuvers are not part of the current CPR protocols, their implementation would be simple and potentially beneficial. It is proposed that clinical or experimental studies evaluate this strategy as an adjuvant in resuscitation.

Keywords

Cardiopulmonary resuscitation, Antishock trusses, Frank-Starling’s law

Introduction

When a patient suffers respiratory arrest, progressive anoxia begins in all organs, including the heart. However, the myocardium has a high oxygen consumption and therefore suffers the consequences of hypoxia particularly rapidly. Among the earliest effects of this energy deprivation is dysfunction of the sodium-potassium pump (adenosine triphosphatases), which leads to a massive leakage of potassium from the cell into the extracellular space.

The accumulation of extracellular potassium generates a sustained depolarization of the membrane potential of myocardial cells. This depolarization reduces the number of sodium channels available for activation, decreases the amplitude of the action potential, and ultimately leads to cellular inexcitability. In this context, cardiac arrest does not necessarily represent myocardial cell death, but rather a functional state of reversible inexcitability.

It has been shown that during acute ischemia, extracellular potassium can reach concentrations of up to 14.7 mmol/L, as experimentally documented by Kléber et al. [1] in isolated guinea pig hearts.

This concept opens up a relevant therapeutic possibility: if myocardial perfusion could be minimally restored-even partially or transiently and this facilitated the removal of accumulated potassium and lactic acid, the myocardium could recover its action potential, automaticity, and contractility.

Conventional CPR achieves only a fraction of normal cardiac output-between 20 and 30% in the best-case scenario [2].

One of the main limiting factors of CPR is the almost nonexistent venous return, which reduces the end-diastolic volume and, consequently, the stroke volume generated by each chest compression. Given that the hemodynamic efficacy of CPR is a crucial determinant of cerebral and coronary perfusion, even small improvements could translate into a significant clinical benefit.

Furthermore, when a person experiences syncope, it is common for those assisting them to elevate their legs in an attempt to increase venous return. Lensini et al. [3] have demonstrated an increase in cerebral blood flow in 10 patients using this technique during CPR. While the immediate cause of syncope is cerebral ischemia, a vagal reflex triggered by the contraction of a virtually empty left ventricle, resulting from the sequestration of blood volume in the lower limbs during prolonged standing, also plays a role. This mechanism has been linked to the Bezold-Jarisch reflex [4].

The development of the anti-gravity suit for aviators in the 1940s later inspired the creation of anti-shock garments designed to counteract hemorrhagic hypotension in wounded soldiers during the Vietnam War [5].