Intravenous isotonic fluid challenge, and L-arginine infusion for oligoamnios and diminished fetal movements: a preliminary study

Background: Utero-placental insufficiency is one of the major causes of oligoamnios and diminished fetal movements (FM). Rapid intravenous isotonic fluid infusion within the cardiovascular reserve improves tissue perfusion in all systems. We tested the hypothesis that isotonic fluid challenge may improve uteroplacental perfusion, which may, in turn improve fetal oxygenation, liquor formation, and FM.Methods: In this descriptive study, twenty-three antenatal mothers with gestational age >26 weeks, and with amniotic fluid index (AFI) <8 cm were included. Intravenous isotonic fluid challenge with 2 or 3 pints of ringer’s lactate, at the rate of 180-200 drops/minute, twice daily for 2-3days and, L-arginine infusion, 300 ml/day alternate days for 2-3 doses were given. Women were advised to take more than 3 litres of water a day. AFI was recorded once daily for 5 days, and then biweekly. The fluid challenge was repeated whenever AFI diminished <8.00 cm. AFI and perceived FM were graded. Pregnancies were terminated when there was no response to fluid challenge. The trend of changes in AFI and FM grades, number of days pregnancies continued, and perinatal outcomes were recorded.Results: We noted recurrent fall in AFI after an initial arise in 20 women, which required recurrent fluid challenges. Pregnancies could be continued for 18±8.5 days (median±SD). Three women, with case of absent FM, reported FM within 1 hour after initiation of the fluid challenge. There were no perinatal deaths.Conclusions: Intravenous isotonic fluid challenge and L-arginine infusion, improves AFI and FM, and helps to prolong pregnancies towards viability.

Brain microdialysis in neurobiology and neurochemistry

Microdialysis is a versatile and popular minimally invasive technique which enables sampling, collecting, and continuous measurement of small-molecular-weight substances in the extracellular fluid of virtually any tissue. Widely established in pharmacology and neuroscience, it permits evaluation of the metabolism in any organ including brain and allows early detection of the cell stress. Concentrations of the target analytes in the dialysate are determined by the type of the analysed tissue, paracrine interactions, and technical features such as membrane type and surface area or flow rate of isotonic fluid. Cerebral (or brain) microdialysis can be used in personalised pharmacotherapy and prognostication in patients with neurological disorders. Here we discuss recent advances in brain microdialysis and focus on critical parameters defining its efficiency.

Bioelectrical impedance analysis does not detect an increase in total body water following isotonic fluid consumption

Purpose: To determine if single-frequency foot-to-foot bioelectrical impedance analysis (BIA) can detect acute changes in total body water (TBW) following consumption of isotonic saline. All participants ate a sodium-free meal at 4 h prior to the data collection visit and had euhydration confirmed using urine specific gravity at the beginning of the experimental visit. Subjects drank 466 mL of isotonic saline (Na+ 140 mmol·L−1) following baseline measures. Blood sampling and BIA were performed at baseline and every 30 min for 3 h after saline consumption. Ten healthy participants completed this study. Plasma volume (5%Δ, p < 0.001) and serum sodium concentration (1%Δ, p < 0.001) increased by 60 min and 90 min, respectively. Body mass (p < 0.001) displayed a biphasic response increasing to a peak at 30 min (+0.38Δkg) and then decreasing to its minimum at 180 min (–0.35Δkg). BIA impedance (p = 0.678) was unaffected by the saline administration. BIA-derived TBW (p = 0.039) decreased from baseline starting at 150 min (0.21Δkg). Novelty Athletes and coaches wishing to achieve hyperhydration can do so through the consumption of isotonic fluid. 50 kHz foot-to-foot BIA-derived TBW is inadequate for measuring hyperhydration. Future studies should examine the physiological and performance effects of such a hyperhydration protocol.

Effect of Environmental Temperature on Serum Sodium Level in Hospitalized Non-critically Ill Children

Background Intravenous hypotonic fluid administered in children is associated with an increased risk of developing hyponatremia. This finding has been reported from temperate countries where climate is relatively cold. But whether this risk also occurs in tropical countries has not been elucidated. Objective The objective of this study was to determine the relationship between environmental temperature and serum sodium in non-critically ill children. Methods A retrospective study. Results A total of 1061 hospitalized children were enrolled. Incidences of hyponatremia were not different between patients who received isotonic and hypotonic fluids (29% vs. 31%). Subgroup analysis showed a trend of higher incidence of hyponatremia in patients who received hypotonic fluid than isotonic fluid only in patients admitted to the air-conditioned wards (29% vs. 21%, p = 0.08). Conclusion Children admitted to the air-conditioned wards who received hypotonic fluid seemed to carry a higher risk of developing hyponatremia than those admitted to the non-air-conditioned ward.