Fluid Therapy Guidelines

Isotonic Fluids

The American Society for Parenteral and Enteral Nutrition recommends isotonic crystalloids as the first-line fluid therapy for volume depletion, hypovolemic shock, and most resuscitation scenarios, with examples including 0.9% normal saline, Ringer's lactate, and balanced crystalloid solutions like Plasma-Lyte 1, 2
Isotonic fluids are recommended for patients with fluid and electrolyte losses from bleeding, vomiting, diarrhea, or excessive blood loss, and should be administered orally, nasogastrically, subcutaneously, or intravenously 1, 2, 3
The Anaesthesia society recommends isotonic crystalloids as first-line therapy to reduce mortality and improve neurological prognosis in acute brain injury patients, as they prevent cerebral edema by maintaining osmotic balance 4, 5, 6
Isotonic fluids prevent hospital-acquired hyponatremia in children, with significantly lower risk compared to hypotonic solutions 7
The Anaesthesia society recommends 0.9% Normal Saline as the most commonly available isotonic crystalloid and current crystalloid of choice in brain injury (osmolality ~308 mOsm/kg) 8, 9
Oral rehydration therapy with isotonic solutions containing sodium, potassium, and glucose is recommended for mild-moderate volume depletion 1, 2

Hypertonic saline (3% NaCl) is specifically indicated for acute management of raised intracranial pressure with impending herniation and severe symptomatic hyponatremia, but not for routine volume resuscitation 8, 9
The Anaesthesia society recommends hypertonic saline for short-term management of impending uncal herniation and mannitol-refractory intracranial hypertension 8, 9
Hypertonic saline bolus is recommended for traumatic brain injury with focal neurological signs, due to its osmotic effect 4
The Anaesthesia society recommends against using hypertonic saline solutions as volume resuscitation solutions for patients with hemorrhagic shock, despite earlier theoretical advantages 4
Meta-analyses show no clear benefit and potential harm when using hypertonic solutions for routine surgical fluid therapy 4

The Intensive Care Medicine society recommends against using hypotonic fluids for fluid resuscitation in sepsis, as they have minimal effect on intravascular volume but carry high risk of tissue edema, brain edema, and dyselectrolytemia 10
The Anaesthesia society recommends against using hypotonic solutions in acute brain injury, as they increase mortality in traumatic brain injury patients (HR 1.78, p=0.035) and should be avoided due to risk of cerebral edema 4, 5, 6
The Pediatrics society recommends against using hypotonic fluids in children for maintenance therapy, as they significantly increase risk of hospital-acquired hyponatremia (RR 0.46 for isotonic vs hypotonic) 7

The Pediatrics society recommends restricting fluids in patients with edematous states, such as congestive heart failure, cirrhosis, or nephrotic syndrome, as they have impaired ability to excrete both free water and sodium 7
The Anaesthesia society recommends against using 4% albumin in traumatic brain injury patients, as it increased mortality (RR 1.63, p=0.003) 4, 5
The Clinical Nutrition society recommends using isotonic fluids in geriatric patients with volume depletion, via any available route (oral, nasogastric, subcutaneous, or intravenous), with assessment based on clinical signs including postural pulse changes ≥30 bpm or presence of ≥4 dehydration signs 1, 2, 3