Volume kinetics of Ringer's solution in female volunteers

Abstract

The kinetics of crystalloid solutions in humans have not been adequately described previously. Therefore, we measured blood haemoglobin concentration during and for 120 min after i.v. infusion of 25 ml kg-1 of Ringer's acetate solution over 15, 30, 45 and 80 min, and 12.5 ml kg-1 over 30 min in six adult female volunteers. The dilution-time profiles were analysed according to a new kinetic model adapted for fluid spaces. Volume expansion produced by Ringer's solution approached steady state in an exponentially decaying manner when plasma volume had increased by approximately 550 ml. The size of the fluid space expanded by Ringer's solution was only 4.8 litre (95% confidence interval 3.8-5.8 litre) except for the fastest infusion, where it averaged 9.0 litre. The rate of fluid elimination could be predicted as the product of plasma dilution and a constant averaging 95 (95% confidence interval 68-122) ml min-1.

Adverse effects of crystalloid and colloid fluids

“…Isotonic, or nearly isotonic crystalloid fluids are harmless up to a volume of 2 L. However, if infused over as short time as 15 min, this volume causes uncomfortable transient sensations of swollenness in the trunk and face, and even dyspnoea [8].…”

Volume kinetics of Ringer’s solution and dextran 3% during induction of spinal anaesthesia for Caesarean section

“…Previously, k r has been determined by the analysis, but the model-predicted urinary excretion agrees well with the measured volume. 8 The plasma dilution, i. e. (Vl--V1)/VI, was used to quantitate the fluid load. This was taken as the product of (1 - body weight, w The model parameters were computed using Matlab version 4.2 (Math Works Inc., Notich, Mass., USA) whereby a non-linear least-squares regression routine based on a modified Ganss-Newton method was repeated until no parameter changed by more than 0.001 (0.1%) in each iteration.…”

Respiratory consequences of perioperative complications related to anaesthesia

“…[5][6][7] Our experimental rat model was intended to mimic continuous insidious surgical bleeding and fluid replacement with solutions commonly used in clinical practice, and allowed us to assess mechanical properties specific for the airway and respiratory tissues following blood loss and replacement. The airway resistance decreased subsequent to the haemorrhage and remained low after fluid therapy with autologous blood, but returned to baseline following colloid and increased slightly after crystalloid.…”

“…A sudden drop in airway pressure reflects the airway properties, whereas a gradual decrease can be attributed to the tissue relaxation and pendelluft between the heterogeneous lung compartments. However, the interrupter airway resistance might not lead to correct estimations of the actual airway resistance due to the substantial involvement of components related to the resistance of the instrument itself and the respiratory tissues [6].…”

“…4 Crystalloids remain a rational option, but clinicians are reluctant to choose them because of the widespread belief that they move rapidly out of the circulation, a belief based on old studies that lacks an adequate evidence basis. [5][6][7] We have recently shown that acute hypovolaemic shock and subsequent resuscitation with autologous blood affects respiratory mechanics. 8 Although surgical procedures are associated with a more controlled but sustained blood loss that also requires fluid replacement therapy, the respiratory consequences of this have not been explored.…”