In the fi eld of medicine and surgery many principles of physics fi nd numerous applications. In this article we have summarized some prominent applications of the laws of fl uid mechanics and hydrodynamics in surgery. Poiseuille's law sets the limits of isovolaemic haemodilution, enumerates limiting factors during fl uid resuscitation and is a guiding principle in surgery for vascular stenoses. The equation of continuity fi nds use in non-invasive measurement of blood fl ow. Bernoulli's theorem explains the formation of post-stenotic dilatation. Reynolds number explains the origin of murmurs, haemolysis and airfl ow disturbances. Various forms of oxygen therapy are a direct application of the gas laws. Doppler effect is used in ultrasonography to fi nd the direction and velocity of blood fl ow. In this fi rst part of a series of articles we describe some applications of the laws of hydrodynamics governing the fl ow of blood and other body fl uids.

No abstract