The clinician should assess the patient's fluid deficit and prescribe appropriate and adequate fluid resuscitation. Most of the patients fluid losses will consist of fluid from the extra-cellular fluid compartment and this should be replaced with either 0.9% saline or Hartmann's solution.
A rough outline is given in table 14. Note that the % of body weight that is water is 70% in a young muscular male and 50 % in an elderly obese female.
The fluid prescription consists of;
The prescription for the next 24 hours should be made up based upon these three quantities. It should include the patient's water and electrolyte requirements. A strict input-output chart should be kept to monitor the fluid balance. The total amount of fluid to be adminstered over the next 24 hours should be broken into periods such that the rate of fluid administration is greatest at the start of the period and least at the end. It would be usual practice in such patients to catheterise the bladder to monitor the urinary output. The clinician should repeatedly assess the patient's response to fluid resuscitation. Over enthusiastic fluid administration may result in pulmonary oedema and too cautious fluid administration may result in dehydration, renal failure and cardio-vascular collapse.
15