Download THE ART OF TRIAGE AND INITIAL STABILIZATION Adam R

THE ART OF TRIAGE AND INITIAL STABILIZATION
Adam R. Lancaster, DVM, Diplomate ACVECC
Head, Emergency and Critical Care Department
BluePearl Veterinary Partners
3412 E. Walton Blvd
Auburn Hills, MI 48067
Part 1: Triage
The word triage is derived from the French word “trier”, a word related to the process of sorting.
The original use of triage was for mass casualty situations (including war) and would identify
patients as immediate, urgent, or non-urgent. Triage, in the medical sense, is the process of
classifying (or sorting) patients into categories based on their level of illness. Importantly, triage
is a dynamic system and patients may change levels based on changes in their status.
There are numerous triage systems that have been developed in human medicine. These include
the Emergency and Severity Index, Australian Triage Scale, Canadian Triage and Acuity Scale,
and Manchester Triage System. These triage systems are generally based on vital signs such as
heart rate or respiratory rate and may include up to 5 levels.
The first veterinary triage scoring system was published in the Journal of Veterinary Emergency
and Critical Care in 1994. This scoring system, called the Animal Trauma Triage (ATT) scoring
system was devised mainly to help stratify patients based on severity of injury for research
purposes. However, it may have some usefulness in identifying patients in a clinical setting that
may require immediate intervention. The ATT scoring system looked at 6 categories including
perfusion, cardiac, respiratory, eye/muscle/integument, skeletal and neurological and assigned a
value from 0 (no injury) to 3 (severe injury) based on predetermined criteria. The animals
therefore could have an overall score of 0-18. This study found that animals with higher ATT
scores had a decreased risk of survival. In fact, for each 1 point increase in ATT there was a 2.3
times lower chance of surviving the trauma. As with any scoring system, application of this
system to an individual patient to predict survival or to influence decisions regarding euthanasia
should be done very cautiously.
Patients should be triaged as soon as possible after arriving to the clinic for an emergency. The
initial evaluation includes the conduction of a primary survey. This primary survey is a brief
examination of the animal focused on assessing vital life functions and the degree of the animal’s
stability. The primary survey can be performed using the ABCDE approach. The A is for airway
and arterial bleeding. Any arterial bleeding should be rapidly identified and measures taken to
control arterial bleeding should be performed very quickly. Likewise, assessment of a patent
airway should be made quickly and animals that do not have an airway will need to be intubated
or a tracheostomy may need to be performed. The B is for breathing and should assess not only
IF the patient is breathing but also whether the patient is breathing normally or is showing signs
of respiratory dysfunction. Oxygen supplementation may need to be provided if respiratory
distress or dysfunction is found. The C stands for circulation and is an assessment of tissue
perfusion. Patients with identified problems with tissue perfusion should be assessed for fluid
statues and adequately fluid resuscitated if deficiencies are noted. The D is for disability and is a
measure of the patient’s mentation and ability to feel pain. Finally, the E stands for External
assessment and is quick overview of any wounds or other external abnormalities.
Once the primary survey has been completed and initial treatments performed (such as
intubation, fluid boluses, etc) a secondary survey can be performed. This includes a more
complete physical examination place any ancillary diagnostics that may need to be performed.
This may include emergency bloodwork (PCV/TS, lactate, electrolytes, blood glucose) or a
Focused Assessment with Sonography for Trauma (FAST) exam.
Triage Classification:
Triage Classification Description Example First Priority Patient Critical Treatment must be initiated within seconds to minutes – Bring immediately to treatment room Major bleeding, breathing problems, altered mentation, shock, history of toxin ingestion, etc. Second Priority Patient Urgent Currently stable, but may become first priority patient, need to be reassessed, or have treatment initiated, within minutes to hours History of major trauma, history of unsuccessful urination, repeated vomiting or diarrhea, etc Third Priority Patient Stable Pressing problem that is non critical Treatment initiated within hours Fever, lacerations, vomiting, diarrhea, etc. Fourth Priority Patient Completely Stable Needs evaluation, but not urgently Skin/coat/ear/anal gland complaints, etc. Part 2: Stabilization
Once a patient has been identified as requiring treatment (first and second priority patients),
initial stabilization and resuscitation may begin. This is often performed concurrently with the
primary and secondary survey. Shock may be simply defined as inadequate oxygen delivery or
tissue perfusion. Building off this simple definition than resuscitation may be defined as
restoration of oxygen delivery and/or perfusion back to normal levels. One way to further
classify shock is to categorize it based on the underlying cause. It this classification scheme
shock may be further categorized as hypovolemic, distributive, hypoxemic, metabolic and
cardiogenic. Of the categories above only cardiogenic typically does not benefit from IV fluid
therapy. In all other cases of shock fluid therapy should be instituted as soon as possible. While
fluid therapy is the main component for many animals in need of stabilization, other treatments
may need to be performed. Hemorrhage should be controlled with bandages or tourniquets as
appropriate. Oxygen supplementation may need to be administered. Hypoglycemia or other
electrolyte disorders need to be corrected if present. And finally, pain medications should be
administered to patients with identified pain or who have been diagnosed with a condition that is
known to be painful. These topics are beyond the scope of this talk and we will focus on fluid
therapy for the remainder of the talk.
Basics of Fluid Therapy
The largest size of IV catheter that you can place in a patient should be used. An 18 or 20 gauge
catheter can be placed on most animals (even cats) although patients with hypotension or
hypovolemia may have small veins and a smaller catheter may need to be used until there is
adequate filling of the veins to place a larger IV catheter.
There are a variety of fluids that may be used for initial resuscitation including isotonic
crystalloids, hypertonic saline and colloids. In most instances, the type of fluid of less
importance than early identification and institution of IV fluid therapy. Isotonic crystalloids are
made of water and electrolytes in various compositions. Some also contain a buffer to make them
less acidic. Types of fluids that would be classified as isotonic crystalloids include 0.9% NaCl,
lactated ringers (LRS), Normosol-R (Norm-R) and Plasmalyte. For most patients, the type of
crystalloid administered does not really matter.
The administration of isotonic fluids leads to good volume expansion (~80% of the volume
infused). Unfortunately this expansion is for a limited time. Isotonic fluids pass out of the ECF
into the interstitium relatively quickly. Within 30 minutes volume expansion is down to 35% and
within 4 hrs only 18% volume expansion remains. Additionally, large volumes of isotonic
crystalloids may lead to interstitial edema. Shock doses of crystalloids are 90 mls/kg in the dog
and 60 mls/kg in the cat. Importantly, the entire “shock” dose should not be administered at
once. Rather a 20-30 ml/kg bolus should be administered in aliquots until the desired endpoints
of resuscitation have been achieved or the total “shock” dose has been administered.
Hypertonic saline (HTS) is a fluid that contains water, Na+ and Cl- similar to physiologic saline
but in higher concentrations (either 7% or 23%). This makes the solution hypertonic to the
plasma. Administration of a hypertonic fluid draws fluid from the intracellular space and
therefore expands the EC space to a degree greater than the volume administered (~3.5x the
volume infused). Similar to isotonic crystalloids, redistribution occurs rapidly. When 4 mls/kg of
7% HTS is administered over 5 minutes there is a 17% increase in IV volume which decreases to
12% at 30 minutes and 3% after 4 hrs. Due to its hypertonic nature, HTS also decreases
intracranial pressure and therefore may be especially helpful in conditions such as traumatic
brain injury. The dose of hypertonic saline is 4 mls/kg and this may be repeated once.
There are 2 major categories of colloids, natural and artificial. Natural colloids including
albumin (both human albumin and canine albumin) and plasma. Artificial colloids include the
hydroxyethyl starches (HES) and dextrans. Dextrans are no longer commercially available so I
will not be discussing these today. Hydroxyethyl starches are categorized based on their
molecular weight, molar substitution and C2:C6 ratio. Products with a higher molecular weight,
increased substitutions and higher C2:C6 ratio have a longer half-life and therefore may have an
increased risk of side effects. Currently there are two main products on the market, hetastarch
and voluven/vetstarch. Of these, hetastarch has a higher molecular weight, increased
substitutions and lower C2:C6 ratio when compared to voluven. As such, lower total daily doses
are recommended. No benefit for colloids over crystalloids has ever been established for
resuscitation of shock. Of note, hydroxyethyl starches have come under increased scrutiny the
past few years due to the development of severe adverse effects in people (namely acute kidney
injury). These products are no longer recommended for use in people and have been pulled off
the market in some countries. Evidence for development of AKI in dogs and cats is lacking,
however. Therefore, these products may still be used with caution in individual patients.
Fluid comparison chart:
Fluid
0.9% (physiologic)
NaCl
Electrolytes
Na+, Cl-
Buffer
No
Indications/usefulness
Useful when do not want
other electrolytes (such as
hyperkalemia)
May be used with blood
products
Cautions
May worsen acidosis
Caution in
hypernatremia and
hyponatremia
Hypercalcemia
LRS
Na+, Cl-, K+,
Calcium
Yes, lactate
Basic resuscitation
Hypocalcemia
Won’t worsen acidosis
Do not use with blood
products
Caution in patients with
lymphoma
May cause elevations in
blood lactate
Plasmalyte
Na+, Cl-, K+,
Mg+
Na+, Cl-, K+,
Mg+
Na+, Cl-
Yes, acetate
and gluconate
Yes, acetate
and gluconate
No
Won’t worsen acidosis
Do not use with blood
products
Do not use with blood
products
Caution in patients with
hyponatremia
Relatively
contraindicated with
hypernatremia
Maximum dose 8
mls/kg/day
Hetastarch (HES)
Na+. Cl-
Provides oncotic support
May be useful in
hypoalbuminemia
Coagulation disturbances
Acute kidney injury
Vetstarch
Na+, Cl-
Sodium
hydroxide
added for pH
adjustment
Sodium
hydroxide
added for pH
adjustment
May be able to give
larger volumes when
compared to HES
Coagulation disturbances
Acute kidney injury
Norm-R
Hypertonic 7%
saline (HTS)
Won’t worsen acidosis
Expands IV space 3.5x
volume infused
Decreases intracranial
pressure
Arteriolar vasodilation
may further increase
perfusion