Thomas Aitchison Latta (1796 – 19 October 1833) was a medical pioneer who was responsible for the introduction of the saline solution ("saline drip") methodology into the treatment of patients.
Thomas Latta is not listed independently in any Post Office Directory so it may be conjectured that he was unmarried and still lived in his parental home. Given the rarity of his surname he was probably the son of Alexander Latta, surgeon, who lived at 6 Union Place at the top of Leith Walk. His maternal grandfather is thought to be Rev Thomas Aitchison of Leith.
He attended University of Edinburgh, graduating in 1819 with his thesis about scurvy.
Saline Solution Drip
This was initially introduced by Latta in 1832 during a cholera epidemic which had reached Britain in the previous year and was killing huge numbers of people. Latta was the leader of a group of three Leith doctor's the other two being Dr Thomas Craigie and Dr Robert Lewins. Whilst all three were based in Leith the experiments were undertaken on five patients in the Edinburgh Cholera Hospital on Drummond Street in Edinburgh (it having already been seen as critical to isolate such victims). Although his results were both remarkably good and effective in saving human lives, the research appeared to thereafter be forgotten for 70 years before rematerialising in more broader use.
Intravenous theory had existed prior to this date but had never been successfully put into practice. The critical aspect of Latta's theory was the nature of the liquid, correctly speculating that a salt solution could substitute for blood. Basing his experiments on the theories of Dr William B O'Shaughnessy, Latta had equally observed that cholera victims lost a huge proportion of water content from their blood. Replenishment of this in combination with "oxygenating salts" were seen as key to patient recovery. The theory was then put into practice. Given that cholera was invariably fatal the patients had little to lose in being treated by this experimental treatment. Latta at first tried to administer this rectally, but on 23 May 1832 he wrote to the Central Board of Health notifying them of his intention to begin the treatment intravenously. This method was an immediate success. His letter described his method and response: "I attempted to restore the blood to its natural state, by injecting copiously into the larger intestines warm water.. trusting that the power of absorption might not be altogether lost, but by these means I produced, in no case, any permanent benefit.. I at length resolved to throw the fluid immediately into the circulation. In this, having no precedent to direct me, I proceeded with much caution. The first subject of experiment was an aged female. She had apparently reached the last moments of her earthly existence, and now nothing could injure her - indeed, so entirely was she reduced, that I feared I should be unable to get my apparatus ready ere she expired. Having inserted a tube into the basilic vein, cautiously - anxiously, I watched the effects; ounce after ounce was injected, but no visible change was produced. Still persevering, I though she began to breathe less laboriously, soon the sharpened features, and sunken eye, and fallen jaw, pale and cold, bearing the manifest impress of death's signet, began to glow with returning animation; the pulse, which had long ceased, returned to the wrist; at first small and quick, by degrees it became more and more distinct ... and in the short space of half and hour, when six pints had been injected, she expressed in a firm voice that she was free from all uneasiness, actually became jocular, and fancied all she needed was a little sleep." 
The results were published in The Lancet on 23 June 1832 and the methodology began to spread, however by then the epidemic was on the wane.
This extract from The Lancet graphically illustrates the treatment: "The very remarkable effects of this remedy require to be witnessed to be believed. Shortly after the commencement of the injection the pulse, which was not perceptible, gradually returns; the eyes, which were sunk and turned upwards, are suddenly brought forward, and the patient looks round as if in health, the natural heat of the body is gradually restored, the tongue and breath, which were in some cases at the temperature of 79 and 80, rise to 88 and 90, and soon become natural, the laborious respiration and oppression of weight of the chest are relieved ... the whole countenance assumes a natural healthy appearance".
Results were however inconsistent, almost certainly because the correct proportions of salt for physiological saline were then unknown, leaving Latta unable to gauge the proportions of potassium, sodium, bicarbonate,and chloride in the blood so as to prevent hemolysis and the destruction of red blood cells. Though a few of Latta's patients appear to have survived, most died after a temporary period of excitation like that described in his letter to the Lancet. The standard use of saline solutions (largely for recovery procedures) did not begin until 1902, when electrolyte balance and the mechanisms of hypovolemic shock were better understood.
Thomas Latta also contributed publications on the subject of Arctic science, after having sailed as "surgeon and companion" with Captain William Scoresby on a whaling expedition, while still a medical student.
He is buried in Leith (he is thought to be in the very small graveyard at North Leith Parish Church on Madeira Street).
As an unsung hero of medicine, Latta is a popular topic for university dissertations.
- Edinburgh and Leith Post Office Directory 1830-1
- Thomas Aitchison Latta (1819). QUAEDAM SCORBUTO COMPLECTENS.
- Leith Hospital 1848-1988 (introduction) by DHA Boyd ISBN 0-7073-0584-5
- Epidemic Cholera in Edinburgh and District, David Craigie (Edinburgh Medical Journal, (37) 1832)
- Hoy, Christine (1988). A Beacon in Our Town: The Story of Leith Hospital. Edinburgh: Christine Hoy. pp. 11–16. ISBN 0951373900.
- "XI Saline Injections in Cholera". The Medico-chirurgical Review and Journal of Medical Science. 21: 241–242. 1 July 1832. Retrieved 14 April 2017.
- Meikle, G. (1832). "Trial of Saline Venous Injections in Malignant Cholera at the Drummond-Street Hospital, Edinburgh". The Lancet. 18 (472): 748. doi:10.1016/S0140-6736(02)82534-X.
- Leith Hospital 1848-1988, by D H A Boyd ISBN 0-7073-0584-5
- Edinburgh and Leith Post Office Directory 1830-31
- Hoy, Christine (1988). A Beacon in Our Town: The Story of Leith Hospital. Edinburgh. pp. 11 – 16. ISBN 0951373900.
- City of Edinburgh Council, street-naming reports, 2014
- Edinburgh A-Z
- Janakan, G; Ellis, H (2013). "Dr Thomas Aitchison Latta (c1796-1833): Pioneer of intravenous fluid replacement in the treatment of cholera". Journal of Medical Biography. 21 (2): 70–4. PMID 24585745. doi:10.1258/jmb.2012.012004.
- MacGillivray, N (2006). "Dr Latta of Leith: Pioneer in the treatment of cholera by intravenous saline infusion". The journal of the Royal College of Physicians of Edinburgh. 36 (1): 80–5. PMID 17146955.
- Baskett, T. F. (2002). "William O'Shaughnessy, Thomas Latta and the origins of intravenous saline". Resuscitation. 55 (3): 231–4. PMID 12458058. doi:10.1016/s0300-9572(02)00294-0.