Fluid therapy in 2015 and beyond: the mini-fluid challenge and mini-fluid bolus approach.

The first description of the use of intravenous fluid in a human is attributed to Dr Thomas Latta during the cholera epidemic in London in 1831–2. Dr Latta described his experience in a letter to the editor of The Lancet. 1 Dr Latta first attempted to replace the lost fluid and salts 'by injecting copiously into the larger intestine warm water, holding in solution the requisite salts, and also administered quantities from time to time by mouth'. 2 3 He found there to be no permanent benefit and considered that the unfortunate sufferers' vomiting and purging were aggravated. Dr Latta wrote 'finding thus, that such, in common with all the ordinary means in use, was either useless or hurtful, I at length resolved to throw the fluid immediately into the circula-tion'. The injected solution was made up of 'two to three drachms of muriate of soda and two scruples of the subcarbonate of soda in six pints of water' (equivalent to approximately ½ Ringers lac-tate). His first patient was an elderly woman who had been given all the usual remedies and who had 'reached the last moments of her earthly existence.' Dr Latta inserted a tube into the basilic vein and 'injected ounce after ounce of fluid, closely observing the patient', at first with no visible effect, but then she began to breathe less laboriously and 'soon the sharpened features, and sunken eye, and fallen jaw, pale and cold, bearing the manifest imprint of death's signet, began to glow with returning animation ; the pulse returned to the wrist. . .'. After 6 pints (2.8 litre) of fluid had been injected, the woman announced in a strong voice that she was now 'free from all uneasiness' and was cured. The technique of fluid resuscitation described by Dr Latta nearly 200 yr ago has stood the test of time, and appears to be the only logical method to resuscitate patients—give repeated small boluses of fluid and observe the patient closely (what a remarkable concept!). This is best done by giving 200–500 ml bo-luses of Ringers lactate solution (or 4% human albumin solution) and closely monitoring the response. While the basic concept has not changed, the single most important advancement since the days of Dr Latta is the ability to measure stroke volume (SV) continuously by minimally invasive or non-inva-sive techniques. 4 This allows the clinician to assess the pa-tient's fluid responsiveness …