Interrelationship between oxygen‐related variables in patients with acute myocardial infarction: an interpretative review

Abstract

The high mortality rate of cardiogenic shock in acute myocardial infarction (AMI) implies that debate over the correct haemodynamic management is still unresolved. The purpose of this review is to re-evaluate the reciprocal relationships between oxygen-related variables and response to treatment in a large number of patients with AMI. A MEDLINE search of reports published between 1970 and 2008 was performed. Twelve clinical reports including 453 patients with AMI and 989 sets of oxygen delivery and oxygen consumption expressed in ml min⁻¹ m⁻² and oxygen extraction ratio were selected. While processing this data, we found an early down-regulation in oxygen demand linked to a decrease in oxygen supply. This mechanism is also supported in some studies by a critically low oxygen uptake that was not associated with lactic acidosis.

Tissue oxygen tension monitoring of organ perfusion: rationale, methodologies, and literature review

“…Thus, an inadequate delivery-for whatever reason-relative to demand will decrease the tP O2 . 14 This can be obviated to some degree by increasing glycolytic ATP production (anaerobic respiration) and by reducing metabolic demands through physiological adaptation or decreasing cellular metabolism, 17 or through iatrogenic intervention, such as by cooling or anaesthesia. On the contrary, a primary reduction in metabolic demand or a pathological failure of oxidative phosphorylation will leave oxygen supply largely unaffected, and thus, the tP O2 will increase.…”

Do critical care patients hibernate? Theoretical support for less is more

“…Oxygen delivery insufficient to meet metabolic needs can result in life-threatening shock. Although this is often the case in early pre-resuscitative critical illness, post-resuscitation oxygen delivery is usually more than adequate due to a relative suppression of cellular oxygen use [16,17]. This transition from energy deficit to hypometabolism again shows similarities between critical illness and torpor.…”