Circulatory Failure. 6 th N ovember 2013. Physiology and pathophysiology of the heart and circulation Pathophysiological effects of altered intravascular volume Pathophysiology and treatment of cardiac failure Theoretical advantages and disadvantages of crystalloid and colloid solutions
CO = HR x SV
D02= CO x Ca02
Ca02= (1.3 x Hb x Sa02) + (0.003 x Pa02)
a substance that in solution can pass through a semipermeable membrane
a suspension of small particles dispersed in another substance
Colloids versus crystalloids for fluid resuscitation in critically ill patients.
Alderson P, Schierhout G, Roberts I, Bunn F
Cochrane Database Syst Rev. 2000;
REVIEWER'S CONCLUSIONS: There is no evidence from randomised controlled trials that resuscitation with colloids reduces the risk of death compared to crystalloids in patients with trauma, burns and following surgery. As colloids are not associated with an improvement in survival, and as they are more expensive than crystalloids, it is hard to see how their continued use in these patient types can be justified outside the context of randomised controlled trials.
Association of hydroxyethyl starch administration with mortality and acute kidney injury in critically ill patients requiring volume resuscitation: a systematic review and meta-analysis.
Zarychanski R, Abou-Setta AM, Turgeon AF, Houston BL, McIntyre L, Marshall JC, Fergusson DA
JAMA. 2013 Feb;309(7):678-88.
CONCLUSION AND RELEVANCE: In critically ill patients requiring acute volume resuscitation, use of hydroxyethyl starch compared with other resuscitation solutions was not associated with a decrease in mortality. Moreover, after exclusion of7 trials performed by an investigator whose research has been retracted because of scientific misconduct, hydroxyethyl starch was associated with a significant increased risk of mortality and acute kidney injury. Clinical use of hydroxyethyl starch for acute volume resuscitation is not warranted due to serious safety concerns.
measurement of the changes of electrical conductivity within the thorax
During diastole, the RBCs in the aorta assume a random orientation, which causes the electrical current to meet more resistance, resulting in a lower measure of conductivity.
During systole, pulsatile flow causes the RBCs to align parallel to both the blood flow and electrical current, resulting in a higher conductivity state.
By analyzing the rate of change in conductivity before and after aortic valve opening, or in other words, how fast the RBCs are aligning, EC technology derives the peak aortic acceleration of blood and the left ventricular ejection time (flow time).
The velocity of the blood flow is derived from the peak aortic acceleration and used within our patented algorithm to derive stroke volume.
CO = oxygen consumption
arteriovenous oxygen content difference