Important physical principles in anaesthesiology

Abstract

The aim of this Review is to introduce anaesthesiologists to the basic physical principles that are important for their work. A better understanding of the underlying processes during anaesthesia is required for greater safety and efficiency. Relevant physical quantities are presented along with the area of anaesthesiology where they are used. This approach provides better targeting to the needs of practising anaesthesiologists. This text has been a part of a specialist course in anaesthesiology at the University of Ljubljana for some years. Current results show that both the students and the specialist anaesthesiologists now show a better understanding of the underlying physical principles required for their work and are more successful in fulfilling the needs of their practical work.

Intraoperative perfusion management impacts postoperative outcomes: An analysis of 682 autologous breast reconstruction patients

“…Higher rates of resuscitation may lead to an increased degree of hemodilution and increased blood velocity resulting in decreased viscosity. 19 It is plausible that higher rates of resuscitation can potentially lead to some of the suggested benefits of hemodilution, which including the reduction of stasis, reduced red cell and platelet aggregation and dilution of clotting factors. 20 True over-resuscitation; however, can lead to medical complications and even increased flap complications.…”

Anesthesia for free vascularized tissue transfer

“…Upstream of the capillaries, the viscosity of blood depends on the hematocrit and the velocity of the flow: the higher the hematocrit or the lower the velocity, the higher the viscosity and vice versa: the lower the hematocrit or the higher the velocity, the lower the viscosity. 6 In moderate hemodilution, the reduction in viscosity is compensated by the increased flow; thus, the shear stress sensed by the endothelium is increased because of the increased flow. Blood viscosity in the larger blood vessels is a quadratic function of the hematocrit, whereas microvascular viscosities are a weak function of the systemic hematocrit.…”

Thermal Damage of the Humidified Ventilator Circuit in the Operating Room

“…Anesthesia equipment was frequently implicated in triggering and/or sustaining combustion. [1][2][3] Each of these events placed the patient at an excessive risk of morbidity. The 2 events described in this report compelled us to analyze the plausible causes of fire, with special emphasis on the role of equipment design.…”