Page 483 - Clinical Small Animal Internal Medicine

46 Medical Management of Trauma and Burns 451

Fluid Therapy Patients that suffer severe trauma or burns should be
VetBooks.ir ment of trauma patients is fluid therapy. Trauma and considered to be very painful and analgesia should be
Arguably the most important part of medical manage-
provided liberally. The best method of pain manage-
burn patients have unique fluid needs that require
modal approach. Pure opioid agonists are the mainstay
special consideration. Judicious use of crystalloid fluids ment in traumatized or burned patients utilizes a multi-
in patients that suffer thoracic trauma and, in particular, of pain management and should be provided early in the
those that develop pulmonary contusions is needed. It course of treatment. Opioid medications have no ceiling
should be remembered that endothelial cell dysfunction effect, meaning that there is no maximum dose at which
and perturbations in vascular integrity might contribute further administration would not be expected to affect a
to fluid loss from the intravascular space. Excessively result. In most cases, administration should be contin-
high volumes of crystalloid fluid may exacerbate pulmo- ued throughout the duration of hospitalization. While
nary contusions due to their rapid redistribution into the opioids are capable of depressing respiratory drive in
interstitial space following administration. Patients veterinary patients, this is rarely clinically relevant.
with head trauma should be treated in a similar fashion. If there is concern over a patient’s ventilatory drive then
If brain edema develops secondary to exuberant fluid the dose of opioid can be reduced or broken into aliquots
resuscitation, cerebral blood flow may be impaired. This and administered to effect.
concern must be balanced by the need to maintain The dissociative agent ketamine has some analgesic
adequate blood pressure for brain perfusion. properties, particularly for superficial pain. More impor-
Hypoproteinemia is common in trauma patients, tantly, perhaps, are the n‐methyl D‐aspartate (NMDA)
especially following burn injury, animal bites, or crush antagonistic properties of ketamine that may alter spinal
injury. The routine use of synthetic colloids in veterinary modulation and prevent or ameliorate central sensitiza-
medicine is somewhat controversial due to concerns asso- tion (wind‐up). In order to derive the full benefit of keta-
ciated with development of coagulopathy and possibly mine with regard to sensitization prevention, it should
renal failure. However, no clinical veterinary trials to be administered for at least 24 hours as a constant rate
date have demonstrated a negative association and their infusion (CRI) (5–15 μg/kg/min). The use of ketamine
use should be considered to maintain colloid osmotic alone is not effective for deep or visceral pain and can
pressure and reduce edema formation in nonaffected result in behavioral changes, therefore ketamine should
tissue. In addition to its importance for maintaining col- almost always be administered in conjunction with an
loid osmotic pressure (COP), albumin is an important opioid. When discontinuing ketamine for patients that
carrier molecule and facilitates healing. Therefore, have been on a CRI for longer than 24 hours, a gradual
canine patients may benefit from receiving human serum reduction of the infusion rate over several hours is used
albumin or canine‐specific lyophilized albumin rather to prevent behavioral changes associated with abrupt
than synthetic starches for colloidal support. discontinuation.
Clinically, the alpha‐2‐agonists are most commonly
Pain Management used for sedation although their use for pain management
The importance of effective pain management goes is becoming more common. Their short half‐lives and
beyond the ethical consideration of ameliorating pain. reversibility make them theoretically attractive options in
The presence of pain causes increases in sympathetic many trauma patients but careful consideration should be
tone and catecholamine secretion, leading to increased taken prior to their use since clinically relevant cardiovas-
cardiac output, peripheral vascular resistance, and myo- cular side‐effects are possible. Animals in shock or with
cardial oxygen consumption. While important for the significant heart disease (especially diseases causing
fight or flight response, these changes, if chronic, fur- decreased systolic function) should not be administered
ther impair oxygen delivery to tissues. In addition to the alpha‐2‐agonists. A CRI is often employed to most effec-
cardiovascular effects of pain, a neuroendocrine tively use this class of drugs as a component of the pain
response occurs, resulting in elevated levels of catabolic management protocol. When used at rates of 0.5–2 μg/
hormones including cortisol while a concurrent decrease kg/h, dexmedetomidine can result in anxiolysis and anal-
in the anabolic hormones insulin and testosterone is gesia without significant cardiovascular side‐effects.
present. The net result of the neuroendocrine response Regional or local anesthesia should be considered as
is the development of a catabolic state characterized an adjunct to traditional, systemic analgesic methods.
by hyperglycemia, type B hyperlactatemia, and keto- The use of regional or local anesthesia often requires
genesis. Treatment of pain reduces or eliminates these coordination with the surgical team since these interven-
responses, facilitates patient evaluation, improves tions often require general anesthesia or sedation to be
patient quality of life, and leads to more rapid healing performed. Placement of diffusion catheters for repeated
and reduced morbidity. administration of local anesthetic medication should be