BIOM2071 Lecture Notes - Lecture 17: Hypovolemia, Baroreflex, Stroke Volume
Document Summary
Pressure (mmhg): continuous physical force exerted on/against object. Resistance (mmhg/l/min): force acting opposite to motion of fluid. Blood flow important not satisfactory unless pressure within physiological limits. Afterload: pressure load during contraction (arterial bp) Heart rate (stroke volume x heart rate = cardiac output) Inotropic state (contractility): changes stroke volume at constant preload and afterload) Sensitive to changes in map and pulse pressure. Causes deterioration in function of vital organs (life threatening) Inadequate perfusion of tissues and organs ( arterial pressure levels) Signs: bp despite hr ( co) and failing perfusion of vital organs (cold, thirst, oliguria) Survival limited by degree of bleeding or delay in replacement. May respond to iv fluids temporary improvement. Drastically declining ejection fraction of heart compensatory mechanisms maintain perfusion until limits exceeded/system fails. Causes: obstetric haemorrhage (pathological placentation or postpartum), thromboembolism and hypertensive disorders. Cardiovascular disease: leading cause of indirect maternal death. Rcog: minor, moderate and severe (500-1000ml, 1000-2000ml, >2000ml)
