Table 1 Characteristics of included studies.
| Brazel (1996)14 | Dagli (1997)16 | Neville (2006)15 | Hoorn (2004)18 | Burrows (1983)17 | Wilkinson (1992)19 | |
|---|---|---|---|---|---|---|
| Participants | ||||||
| n | 12 | 60 | 104 | 148 | 24 | 56 |
| Age (years) | 12.3–18.1 | 1–12 | 6 months–14 years | 7±6 | 6–16 | 2 months–14 years |
| Inclusion criteria | Adolescent females undergoing idiopathic scoliosis repair | ASA 1 patients undergoing elective minor surgery | Gastroenteritis with dehydration | 37 patients with hospital acquired hyponatraemia, 111 isonatraemic historical controls | Previously healthy patients with idiopathic scoliosis undergoing surgical correction | Craniofacial surgery |
| Methodology | RCT, unmasked | Controlled trial | RCT, unmasked | Case control | Cohort study | Retrospective chart review |
| Intervention (all solutions included appropriate dextrose content unless otherwise stated) | Near isotonic solution (LR), n = 5; v hypotonic solutions: (0.3%–0.18% NaCl), n = 7 | Gp 1: LR Gp 2: 1% Dextrose in LR Gp 3: 3.3% Dextrose in 0.3% NaCl | Gp1: 0.45% NaCl Gp 2: 0.9% NaCl | Standard prescription for maintenance IV fluids | Postoperative maintenance fluids: Isotonic (LR), n = 4 Hypotonic (0.25–0.5% NaCl), n = 20 | Isotonic (LR or NS), n = 30 Hypotonic (0.16–0.5% NaCl), n = 26 |
| Outcomes | ||||||
| PNa mmol/l | Greater and more sustained drop in PNa in hypotonic group (p<0.01) | Post‐op PNa in Gp 3 significantly lower (p<0.05). No significant change in Gp 1 and 2 | Mean PNa after 4 hours: Gp 1 134.3 mmol/l (2.1) Gp 2 136.3 mmol/l (3.3) | Cases: PNa dropped from 139±3 to 133±2 mmol/l in 19±10 hours Controls: PNa 140±2 mmol/l | Greater fall in PNa in hypotonic group: 6.2±2.9 mEq/l (p⩽0.05); 3.0±0.8 mEq/l in isotonic group | Median PNa: 130.5 (121–136) in hypotonic Gp; 139 in isotonic group |
| Hyponatraemia (PNa <136) | 1 patient in LR group, 7 in hypotonic group | PNa in hypotonic group (Gp 3): 133.3±4.6 mEq/l (p<0.05) | 21/31 in Gp 1, 2/21 in Gp 2 | All cases by definition | Post‐op PNa: 131±2.8 in hypotonic group; 135±1.9 mmol/l in isotonic group | 20/26 patients in hypotonic group, 2/30 in isotonic group |
| Severe hyponatraemia (PNa <130) | 4 in hypotonic group | Not described | 5/22 in Gp 1 (PNa ⩽130); 0/22 in Gp 2 | Not described | 5 patients in hypotonic group | 11 in hypotonic group |
| Clinical sequelae related to hyponatraemia | Not mentioned | Not described | None described | More nausea and vomiting reported in hyponatraemic group | Increased interstitial pulmonary fluid in hypotonic group (p<0.05) | Seizures: 2/26 in hypotonic group |
| Hypernatraemia (PNa >145) | None | None | None | None | None | None |
CVS, cardiovascular; LR, Lactated Ringers; NS, normal saline; PNa, plasma sodium; pre/post‐op, pre‐ or postoperative; Gp, group; NaCl, sodium chloride; RCT, randomised controlled trial.