Yeah, but what about the patient who walks in off the street with a 19% hematocrit, with a pulse >100 and a BP of 100/60. And yes, now that you mention it, he does get tired pretty easily.
Amazing how divergent my education is from the recent literature on this topic.
Things I've been taught
- isotonic crystalloids are essentially equivalent, and it doesn't matter which one you use
- NS & LR are cheap and available, pick one and use it
- aggressive fluid resuscitation is the cornerstone of shock treatment in most cases
- LR may reduce the risk of fluid-induced hyperchloremic metabolic acidosis, because it is closer to physiologic pH than NS
- Give 3L of crystalloid (or equivalent 20cc/kg x 3 in kids), if no response, then consider blood transfusion
And here's what a 2-minute PubMed search says:
Shock. 2006 Aug;26(2):115-21.
"Increasing evidence has demonstrated that
aggressive crystalloid-based resuscitation strategies are associated with cardiac and pulmonary complications, gastrointestinal dysmotility, coagulation disturbances, and immunological and inflammatory mediator dysfunction. As large volumes of fluids are administered, imbalances in intracellular and extracellular osmolarity occur. Disturbances in cell volume disrupt numerous regulatory mechanisms responsible for keeping the inflammatory cascade under control. Several authors have demonstrated the detrimental effects of large, crystalloid-based resuscitation strategies on pulmonary complications in specific surgical populations. Additionally,
fluid-restrictive strategies have been associated with a decreased frequency of and shorter time to recovery from acute respiratory distress syndrome and trends toward shorter lengths of stay and lower mortality. Early resuscitation of hemorrhagic shock with predominately saline-based regimens has been associated with cardiac dysfunction and lower cardiac output, as well as higher mortality. Numerous investigators have evaluated potential risk factors for developing abdominal compartment syndrome and have universally noted the excessive use of crystalloids as the primary determinant. Resuscitation regimens that cause early increases in blood flow and pressure may result in greater hemorrhage and mortality than those regimens that yield comparable flow and pressure increases late in resuscitation. Future resuscitation research is likely to focus on improvements in fluid composition and adjuncts to administration of large volume of fluid."
Surg Clin North Am. 2007 Feb;87(1):55-72, vi.
"
LR may be safe in small doses that the body can obviously tolerate, but not in larger amounts given over short periods following hemorrhagic shock and trauma. Modifications of LR, such as elimination of d-lactate, can decrease these adverse effects, and complete substitution of lactate with other monocarboxytates (eg, ketone bodies or pyruvate) seems to be beneficial. . .
In trauma, fluid resuscitation is only needed in patients who have lost blood. It is clear that not all the trauma patients need fluid resuscitation. For bleeding patients intravenous access is critical but should not be synonymous with fluid infusion. In the absence of traumatic brain injury, permissive hypotension with systolic pressures greater than 80 mm Hg, consciousness, or palpable pulse are reasonable goals until hemorrhage has been controlled.
Rather than resuscitating the patient before definitive hemorrhage control, emphasis should be on controlling hemorrhage and using fluids only to keep the patient alive during the process. It can be argued that the initial fluid of choice among commercially available fluids in the United States should be 5% HTS because it is commercially available.
Two 250-mL boluses are safe and offer many potential advantages. This should be followed by infusion of l-isomer LR (Baxter, Deerfield, Illinois) if further volume expansion is needed. For the hypotensive bleeding patient, initiation of blood transfusion should be early, and blood component therapy should be initiated immediately without waiting for the development of coagulopathy. Thawed fresh frozen plasma should be given in a 1:1 ratio to packed red blood cells."
