Impact of perioperative hyponatremia in children: A narrative review

Table 1 The 4-2-1 formula for maintenance fluids in children[10,11]

Weight	Daily fluid requirements	Hourly fluid requirements
3-10 kg	100 mL/kg	4 mL/kg per hour
11-20 kg	1000 mL + 50 mL for every kilogram > 10	40 mL/h + 2 mL/h for every kilogram > 10
> 20 kg	1500 mL + 20 mL for every kilogram > 20	60 mL/h + 1 mL/h for every kilogram > 20

Table 2 Stimuli associated with increased antidiuretic hormone production (adapted from Bailey et al[15])

Hemodynamic
Hypotension
Hypovolemia	Blood loss, diarrhea, diuretics, vomiting, renal salt wasting, hypoaldosteronism, burns, polyuria
Hypervolemia	Nephrotic syndrome, cirrhosis, heart failure, hypoalbuminemia, iatrogenic-induced hyponatremia, excessive water intake
Non-hemodynamic
Central nervous system disturbances	Meningitis, encephalitis, brain abscess, head injury, hypoxic brain injury, stroke
Pulmonary diseases	Asthma, pneumonia, chronic obstructive pulmonary disease, tuberculosis, empyema, bronchiolitis, acute respiratory failure
Cancer	Lung cancer (especially small-cell lung cancer), brain tumor, leukemia, lymphoma, pancreatic cancer, prostate cancer, ovarian cancer, neuroendocrine tumor, squamous cell carcinoma
Medications	Selective serotonin reuptake inhibitors, morphine, carbamazepine, cyclophosphamide, vincristine, desmopressin
Other	Pain, stress, nausea, emesis, postoperative state, cortisol deficiency

Table 3 Most commonly available crystalloid and human albumin solutions in Europe

Fluid	Na+	K+	Cl-	Lactate	Acetate	Glucose	Osmolarity	Tonicity
	(mmol/L)	(mmol/L)	(mmol/L)	(mmol/L)	(mmol/L)	monohydrate (g/L)	(mOsm/L)	(to plasma)
Isotonic NaCl	154	0	154	0	0	0	308 (iso-osmolar)	Isotonic
Ringer’s lactate	130	4	109	28	0	0	270 (iso-osmolar)	Isotonic
Ringer’s acetate	130	4	110	0	30	0	270 (iso-osmolar)	Isotonic
Darrow-glucose “SAD”	31	9	26	14	0	55	360 (hyperosmolar)	Hypotonic
Human albumin 5%	130-160	< 3	0	0	0	0	330 (hyperosmolar)	Isotonic
Human albumin 20%	100-160	< 3	0	0	0	0	300 (hyperosmolar)	Hypertonic
Glucosalin 2:1 (Glucose 3.3%/NaCl 0.3%)	51	0	51	0	0	33	287 (iso-osmolar)	Hypotonic
Glucose 2.5%/NaCl 0.45%	77	0	77	0	0	25	293 (iso-osmolar)	Hypotonic
Glucose 4%/NaCl 0.18%	31	0	31	0	0	40	284 (iso-osmolar)	Hypotonic
Glucose 5%/NaCl 0.45%	77	0	77	0	0	50	432 (hyperosmolar)	Hypotonic
Glucose 4.6%/NaCl 0.9%	154	0	154	0	0	46	561 (hyperosmolar)	Isotonic
Glucose 9.1%/NaCl 0.9%	154	0	154	0	0	91	813 (hyperosmolar)	Isotonic
Glucolyte (Glucose 5%/NaCl 0.3%/KCl 0.15%)	51	20	71	0	0	50	420 (hyperosmolar)	Hypotonic