The history of saline in modern day medicine
Saline solutions are used in medical clinic and hospitals world wide. Today a 0.9% sodium chloride solution is the standard concentration used. Today saline solutions are commonly used throughout health care settings for flushing of wounds, and in the treatment of severe dehydration through intravenous therapy. How did this practice evolve and why is it effective?
The evolution of saline:
Saline use first appeared in medical history during the 1831 Blue cholera epidemic that swept over Europe. Experimentation with saline solutions was first attempted to treat those suffering from severe dehydration. Intestinal infections such as enterococcus or cholera may cause severe dehydrations resulting fromacute bouts of vomiting and diarrhea.
Salt concentrations of saline solutions continued to vary through medical history from its initial synthesis and use in 1831. The clinical trials, chemical synthesis and resultant medical changes in practice continued for the next 175 years. Today 0.9% saline is standard use.
Saline as an osmotically balanced solution to restored lost fluid from the body cells and tissues.
Dehydration may have many causes. An individual may become dehydrated through inadequate fluid intake, trauma leading to heamorhage, or illnesses such as Norwalk virus or cholera infections which cause dehydration through acute boughts of vomiting or diharea.
Cellular Anatomy and Physiology:
Our bodies are composed mostly of water. Fluids are either intracellar (inside cells) or extracellular (outside cells). There are many types of extracellular fluid in the human body. Fluid inside the membrane of the heart is called serous fluid. Another is the fluid or the watery component of the blood is called the blood serum.
Our cells require adequate hydration to function properly. If the cell fluid volume drops due to dehydration, fluid from outside the cells, extracellular fluid is drawn into the cells to hydrate them. In a severely dehydrated individual, both the intracellar and extracellular fluid volume will be dramatically decreased.
Extracellular fluid in the human body:
composed mostly of salt (NaCl).
It is a saline solution
Extracellular fluid contains:
90% sodium ions (Na+)
chloride ions (Cl-)
bicarbonate ions that act as pH buffers
An osmotically balenced water and salt solution.
The standard saline solution used in medical treatments is one of 0.9% saline.
This means that a 100ml saline solutons contains:
0.9% or 0.9 ml of the solution is salt or sodium and chloride ions
99.1% or 99.1ml of that 100ml solution is water.
Intravenous rehydration functions by restoring lost extracellular fluid with a properly balenced supplement (saline). Dehydrated cells may then also become rehydrated as they take up needed fluid from outside the cell (from the extracellular fluid)
Allison, Simon, P, Awad, Sherif, and Lobo, Dileep, N. 2008. The history of 0.9% saline. Clinical Nutrition. 27 (2) 179-188.
Martini, Fredric, H. 2006. Fundamentals of anatomy and physiology. 7th ed. Pearson Education Inc. USA.