Page 442 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

430 FLUID THERAPY

hemoglobin on nitric oxide. This effect may be of benefit POSTOPERATIVE FLUID
in some severely hypotensive and hypovolemic patients in MANAGEMENT
which an immediate increase in blood pressure would be
desirable.Oxyglobinalsowouldbeveryusefulinananimal The patient will continue to lose fluids over time and may
that fails to crossmatch to existing donors and yet needs have decreased food and water intake after surgery. Con-
increased oxygen-carrying capacity intraoperatively. 46 sequently, it is essential to consider fluid therapy in the
Experimentally, it has been shown that Oxyglobin results postoperative period. The choice of fluid is governed
in a more rapid increase in muscle tissue oxygenation than by factors similar to those used before and during surgery.
occurs with the infusion of a similar dose of stored packed A main factor to consider is when the animal is likely to be
cells. 174 Thisobservationsuggeststhatanimalswithsevere able to regulate its own fluid balance. With minor surgical
shock, anemia, orischemia may benefit from an infusion of procedures, this may be almost immediately after surgery,
Oxyglobin as an initial treatment that could then be but with procedures in which recovery is slow or oral
followed by more Oxyglobin or the use of blood products. intake is contraindicated, it is necessary to continue fluid
therapy. Continuing fluid therapy may be particularly
CRYSTALLOIDS VERSUS important in geriatric patients because they often are
COLLOIDS unwilling to drink in the hospital environment and may
be at greater risk because of marginal renal function.
There has been a long debate over the nature of the fluid
that should be used for volume expansion. In the human
medical literature, this question has been addressed in a REFERENCES
number of reviews. The most recent review in the
Cochrane database for the use of crystalloids or colloids 1. Aarnes TK, Bednarski RM, Lerche P, et al. Effect of intra-
in critically ill patients states, “There is no evidence from venous administration of lactated Ringer’s solution or
hetastarch for the treatment of isoflurane-induced hypo-
random controlled trials (RCTs) that resuscitation with tension in dogs. Am J Vet Res 2009;70:1345–53.
colloids reduces the risk of death, compared to resuscita- 2. Abbott TR. Changes in serum calcium fractions and cit-
tion with crystalloids, in patients with trauma, burns or rate concentrations during massive blood transfusions
following surgery.” As colloids are not associated with and cardiopulmonary bypass. Br J Anaesth
1983;55:753–9.
an improvement in survival, and as they are more expen-
3. Adrogue HJ, Tannen RL. Ketoacidosis, hyperosmolar
sive than crystalloids, it is hard to see how their continued
states, and lactic acidosis. In: Kokko JP, Tannen RL,
use in these patients can be justified outside the context of editors. Fluids and Electrolytes. 3rd ed Philadelphia:
RCTs. 137 In isoflurane-induced hypotension (80 mm Hg W.B. Saunders; 1996. p. 643–74.
systolic arterial blood pressure [SAP]) in dogs, an HES 4. Akanji AO, Bruce MA, Frayn KN. Effect of acetate infu-
sion on energy expenditure and substrate oxidation rates
(6% HES 450) infusion of 40 mL/kg restored blood
in non-diabetic and diabetic subjects. Eur J Clin Nutr
pressure in 4 of 6 animals but 80 mL/kg LRS did not 1989;43:107–15.
1
successfully resuscitate any animal. In dogs made hypo- 5. Allard RL, Carlos AD, Faltin EC. Canine hematological
tensive (80 mm Hg SAP) by blood loss, restoration of changes during gestation and lactation. Companion Ani-
blood pressure to within 10% of control took 194 mL mal Practice 1989;19:3–6.
6. Allon M, Copkney C. Albuterol and insulin for treatment
of HES as compared with 749 mL of LRS. In the former
of hyperkalemia in hemodialysis patients. Kidney Int
experiment, the authors concluded that HES should be 1990;38:869–72.
used rather than LRS to treat isoflurane-induced hypo- 7. Anand IS, Ferrari R, Kalra GS, et al. Edema of cardiac ori-
tension. However, in neither of these experiments were gin. Studies of body water and sodium, renal function,
the cardiac indices different between treatments, hemodynamic indexes, and plasma hormones in untreated
congestive cardiac failure. Circulation 1989;80:299–305.
suggesting that both solutions restored systemic blood 8. Asao Y, Hirasaki A, Matsushita M, et al. A patient who
flow. In the isoflurane experiment, oxygen delivery was recovered successfully from severe anemia which
no different between treatments either, further continued for one hour. Masui 1997;46:700–3.
supporting the notion that blood pressure is not a partic- 9. Baer RW, Vlahakes GJ, Uhlig PN, et al. Maximum
ularly good goal for therapy. 129 Colloidal solutions myocardial oxygen transport during anemia and polycy-
should increase vascular volume faster and for a longer themia in dogs. Am J Physiol 1987;252:H1086–H1095.
10. Baraff LJ. Capillary refill: Is it a useful clinical sign? Pedi-
period of time than crystalloids, and therefore may be
atrics 1993;92:723–4.
useful when colloid osmotic pressure is low or when 11. Barron ME, Wilkes MM, Navickis RJ. A systematic review
crystalloids are not working well because their effect is of the comparative safety of colloids. Arch Surg
transient. However, given the evidence cited above, use 2004;139:552–63.
12. Bennett-Guerrero E, Kahn RA, Moskowitz DM, et al.
of crystalloids as a primary form of fluid therapy still
Comparison of arterial systolic pressure variation with
seems justified with the addition of colloids when neces-
other clinical parameters to predict the response to fluid
sary to improve COP, oxygen delivery, or to prolong the challenges during cardiac surgery. Mt Sinai J Med
achieved increase in circulating volume. 2002;69:96–100.