title: Principles of physics in surgery: the laws of flow dynamics physics for surgeons - Part 1.
abstract: In the field of medicine and surgery many principles of physics find numerous applications. In this article we have summarized some prominent applications of the laws of fluid mechanics and hydrodynamics in surgery. Poiseuille's law sets the limits of isovolaemic haemodilution, enumerates limiting factors during fluid resuscitation and is a guiding principle in surgery for vascular stenoses. The equation of continuity finds use in non-invasive measurement of blood flow. Bernoulli's theorem explains the formation of post-stenotic dilatation. Reynolds number explains the origin of murmurs, haemolysis and airflow disturbances. Various forms of oxygen therapy are a direct application of the gas laws. Doppler effect is used in ultrasonography to find the direction and velocity of blood flow. In this first part of a series of articles we describe some applications of the laws of hydrodynamics governing the flow of blood and other body fluids.
authors.affiliation: Department of Surgery, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Anurag
authors.initials: A
authors.lastname: Srivastava
authors.forename: Akshay
authors.initials: A
authors.lastname: Sood
authors.forename: S Parijat
authors.initials: SP
authors.lastname: Joy
authors.forename: John
authors.initials: J
authors.lastname: Woodcock
keywords: Bernoulli’s; Doppler effect; Equation of continuity; Hydrodynamics; Poiseuille’s; Reynolds number