Author and Year | Design | Setting | Participants (sample size) | Bioelectrical Impedance Analysis | Comparators |
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Jones, et al. [30] (2015) | Prospective, observational cohort (single centre) | Australia | Subjects (n = 61) admitted to the ICU who received mechanical ventilation and with an expected hospital stay of ≥ 48 h Patients with dehydration had a mean age of 66 years Sex: Female (38%) and male patients (62%) | Bioelectrical impedance vector analysis (Renal EFG BIVA™ Technology; EFG Diagnostic, Belfast, UK) Impedance of 50 kHz Pairs of electrodes were placed on the dorsum of the wrist and the ipsilateral ankle | A comparator was not used |
Kafri, et al. [31] (2013) | Prospective, observational cohort (single centre) | United Kingdom | Older adults (n = 27) admitted to hospital with acute stroke Patients with dehydration had a mean age of 73.5 years Sex: Not reported | Multi-frequency BIA (Maltron BioScan® 920–2; Maltron International, Essex, UK) Impedance of 5 kHz, 50 kHz, and 100 kHz Pairs of electrodes were placed on the talus and the third and fifth digits of the foot and the third and fifth knuckles of the hand and the wrist | Serum osmolality was analysed using freezing point depression (295–300 mOsm/kg) (i.e. impending dehydration), with current dehydration being ≥ 301 mOsm/kg Serum osmolarity (mOsm/L) was calculated from combined concentrations of serum sodium, potassium, glucose, and urea ([2 × Na +] + [2 × K +] + urea + glucose) (i.e. 295–300 mOsm/L [impending dehydration], with dehydration at the time of the study of ≥ 301 mOsm/L) |
Powers, et al. [22] (2009) | Randomised non-controlled study | United States | Older adults (n = 32) admitted to medical and surgical wards Patients with dehydration had a mean age of 77.1 years Sex: Female (63%) and male patients (37%) | Single-frequency BIA (Real-Time RJL Systems® Analyser, Clinton Township, Michigan, USA) Impedance of 50 kHz Pairs of electrodes were placed on the dorsal surfaces of the right hand and foot proximal to the metacarpal, phalangeal, and metatarsal phalangeal joints One additional pair of electrodes were applied at the pisiform bone of the right wrist and between the medial and lateral malleoli of the right ankle | TBW was determined by 2H2O dilution, and ECW was measured by using sodium bromide (NaBr) dilution The participants provided baseline blood samples To measure TBW, the participants were asked to drink water containing 2H2O at an amount of 30 mg/kg of body weight. To measure ECW, the participants were asked to drink water containing NaBr at an amount of 70 mg/kg of body weight A second blood sample was obtained 3–4 h after the oral dose. Plasma was separated from the blood samples Isotope ratio mass spectroscopy was used to determine 2H2O in the plasma. TBW was calculated using the following equation: TBW = [2H2Odose/(2H2O 3 h – 2H2O 0 h)]/1.04 To measure ECW, NaBr dilution was assayed by using a high-performance liquid chromatography anion-exchange method after serum ultrafiltration. The equation used for the ECW calculation was: ECW = [Br Dose/(Br dose 3 h – Br dose 0 h)] × 0.90 × 0.95 ICW was calculated as TBW – ECW |
Ritz [32] (2001) | Prospective observational cohort (multi-centre) | France | Older adults (n = 169) admitted to geriatric wards for acute medical problems across six hospitals Patients with dehydration had a mean age of 81.4 years Sex: Female (64%) and male patients (36%) | Multi-frequency BIA (Analycor-3®; Spengler, Cachan, France) Impedance of 5 kHz, 50 kHz, and 100 kHz, with current of 400 µA Pairs of electrodes were placed on the distal end of the third metacarpal bone and the distal end of the second metatarsal bone. One additional pair of electrodes was applied between the styloid processes of the radius and ulna and between the two malleoli of the ankle | Dilution measurements of deuterated water (H218O) for TBW and Br dilution for ECW The patients were considered dehydrated if they had plasma sodium levels of ≥ 142 mmol/L, and they were considered euhydrated if their plasma sodium concentrations were ≤ 135 mmol/L At baseline, overnight fasting (approximately 12 h) was required, and the participants provided plasma and urine samples to determine the natural abundance of H218O enrichment and Br concentration An amount of 2% of H218O-enriched water (approximately 50 g) was orally administered to the subjects, and 20 g of potassium Br syrup (containing approximately 1 g of Br) was given to half the participants. After an interval of 4–5 h, the plasma and urine samples were collected The following equation was used to calculate ECW after considering the mean Br plasma concentration 4 and 5 h after the dose: ECW = 0.90 × 0.95 × (Br dose) ⁄ [delta(Br plasma)] Br dose = the dose given and delta (Br plasma) = the difference in mean plasma concentration between the administration of the dose and the baseline concentration |