Crystalloid solution

Ringer s lactate, in which lactate is added to Ringer s solution, is probably the most popular crystalloid (salt) solution for intravenous use in humans. The lactate is gradually converted to sodium bicarbonate within the body so that an uncompensated alkalosis is prevented (13). These crystalloid solutions cannot support life without red cells saline passes rather quickly into the tissue spaces of various organs (14), especially the Hver (15). 

Introduce an intravenous catheter and apply volume (crystalloid solutions like saline or Ringer s)... 

Volume replacement is crucial in antianaphylactic treatment. It should be started with crystalloid solution (saline or Ringer s solution). However, in severe shock, higher... 

The volume of colloid administered is primarily confined to the intravascular space, in contrast to isotonic crystalloid solutions that distribute throughout the extracellular fluid space. 

Therapeutic intravenous (TV) fluids include crystalloid solutions, colloidal solutions, and oxygen-carrying resuscitation solutions. Crystalloids are composed of water and electrolytes, all of which pass freely through semipermeable membranes and remain in the intravascular space for shorter periods of time. As such, these solutions are very useful for correcting electrolyte imbalances but result in smaller hemodynamic changes for a given unit of volume. 

The tonicity of crystalloid solutions is directly related to their sodium concentration. The most commonly used crystalloids include normal saline, hypertonic saline, and lactated Ringer s solution. Excessive administration of any fluid replacement therapy, regardless of tonicity, can lead to fluid overload, particularly in patients with cardiac or renal insufficiency. 

Colloids are larger molecular weight solutions (more than 30,000 daltons) that have been recommended for use in conjunction with or as replacements for crystalloid solutions. Albumin is a monodisperse colloid because all of its molecules are of the same molecular weight, whereas hetastarch and dextran solutions are polydisperse compounds with molecules of varying molecular weights. 

The theoretical advantage of colloids is their prolonged intravascular retention time compared to crystalloid solutions. Isotonic crystalloid solutions have substantial interstitial distribution within minutes of IV administration, but colloids remain in the intravascular space for hours or days, depending on factors such as capillary permeability. However, even with intact capillary permeability, the colloid molecules eventually leak through capillary membranes. 

Albumin 5% and 25% concentrations are available. It takes approximately three to four times as much lactated Ringer s or normal saline solution to yield the same volume expansion as 5% albumin solution. However, albumin is much more costly than crystalloid solutions. The 5% albumin solution is relatively iso-oncotic, whereas 25% albumin is hyperoncotic and tends to pull fluid into the compartment containing the albumin molecules. In general, 5% albumin is used for hypovolemic states. The 25% solution should not be used for acute circulatory insufficiency unless diluted with other fluids or unless it is being used in patients with excess total body water but intravascular depletion, as a means of pulling fluid into the intravascular space. 

Human plasma has a colloid osmotic pressure of 3.6 kPa, of which 2.8 kPa is contributed by albumin. Volume-for-volume, 4.5% albumin is approximately four times more effective in expanding the plasma volume than crystalloid solutions, and the effect lasts 6-8 hours, compared to only 15-20 min with crystalloids. Although popular in the past as volume expanders, albumin solutions have fallen into disfavour. They are prepared from pooled human plasma, with all the inherent risks of pooled blood products. Albumin can cause adverse reactions, similar to other transfusion reactions, such as chills, urticaria, and vasodilatation. These may be caused by organic or inorganic substances formed during the processing... 

In an emergency, speed of replacement is more important than its nature. Crystalloid solutions, e.g. 

A 34-year-old Tongan man complained of sore eyes, headache, generalized muscle weakness, and abdominal pain (21). He was disoriented and hallucinating. His family reported that he had been drinking large quantities of kava daily for about 14 years. Chronic kava intoxication was treated with intravenous Plasmalyte (a crystalloid solution) and he recovered within a day. 

Schierhout G, and Roberts 1.1998. Fluid resuscitation with colloid or crystalloid solutions in critically ill patients a systematic review of randomised trials. Bmj 316 961-964. 

Crystalloid solutions consist of electrolytes in water. Crystalloid solutions may be isotonic, hypertonic or hypotonic. Isotonic solutions have approximately the same osmolality as plasma and, therefore, may be given rapidly in large volumes into peripheral veins. Hypertonic solutions act to draw water into the extracellular fluid (ECF) from the intracellular fluid and represent a method of rapidly restoring circulating volume at the expense of tissue hydration. Hypotonic solutions are usually only used to correct plasma hypertonicity. Because true hypotonic solutions (e.g. sterile water) cause erythrolysis (Krumbhaar 1914), they can only be given slowly via a central vein (Worthley 1986). For this reason, isotonic solutions containing a metabolizable substrate, such as dextrose, and no electrolytes are usually used. 

Table 17.3 outlines the features of polyionic crystalloid solutions. For most situations in the field, commercial isotonic polyionic crystalloid solutions are the safest fluids with which to resuscitate hypovolemic horses (Table 17.3). They increase plasma volume without directly causing profound electrolyte disturbances because they contain...

Colloids are solutions containing large sugar or protein molecules in addition to the water and electrolytes found in crystalloid solutions. All colloids, except albumin, contain a mixture of large and small protein or sugar molecules. The larger molecules allow coUoid solutions to persist longer in the... 

The use of colloids has recently been advocated for the resuscitation of hypovolemic horses and for the treatment of severe hypoproteinemia (McFarlane 1999). Colloids have two advantages over crystalloids that makes them attractive for fluid therapy. Firstly, because of their persistence in the circulation, a three to six times lower volume of a colloid solution is required to produce the same resuscitative effect as a crystalloid solution (Rackow et al 1987). This is particularly useful in acute resuscitation of severely dehydrated horses or in the field where large amounts of crystalloids may be difficult to transport. Secondly, the administration of colloids can increase colloidal oncotic pressure, in contrast to the administration of large volumes of crystalloids, which decreases the colloidal oncotic pressure (Jones et al 1997,2001). 

Recent meta-analyses of randomized trials of colloid administration to human critical care patients demonstrated no advantage of colloids over crystalloids and concluded that colloids increased mortality when used in some clinical syndromes (Choi et al 1999, Schierhout Roberts 1998). When trauma patients were studied as a subpopulation, a 12.3% difference in mortality rate was identified in favor of crystalloid therapy. Conversely, analysis of pooled data from nontrauma patients identified a 7.8% difference in mortality rate in favor of colloid treatment (Velanovich 1989). The majority of clinical trials in these meta-analyses compared albumin with crystalloid solutions and thus these results should not discourage the use of hydroxyethyl starches in horses. 

Lactic acidosis should be treated with large volumes of polyionic crystalloid solutions. As discussed above, the use of sodium bicarbonate in lactic acidosis is highly controversial and not recommended (Forsythe Schmidt 2000). 

Maintain adequate cardiovascular function—-intravenous crystalloid solutions and vasopressors (e.g., dopamine, norepinephrine) if required. 

Crystalloid solutions are preferred over colloid solutions for circulatory insufficiency owing to decreased plasma volume. 

Unfortunately, beneficial outcome data attributable to administration of these hypertonic solutions also have been lacking. Most of these studies were conducted in prehospital and emergency department settings using 250 mL 7.5% sodium chloride with or without 6% dextran-70. A meta-analysis of randomized, controlled trials found no statistical difference between the survival rates of patients receiving the hypertonic saline solutions and those receiving standard isotonic crystalloid solutions.Part of the explanation for this finding may... 

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