artículo de manejos terapéuticos de cuidados intensivos (1)

7/27/2019 Artculo de Manejos Teraputicos de Cuidados Intensivos (1)

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ArticleCritical Care of Exotic Companion Mammals

Exotic companion mammals present frequently for illness and critical care. Some mammals are prey species, and

tend to hide signs of illness until unable to do so.

IDENTIFICATION OF THE CRITICAL PATIENT

Clinic staff must be trained in over-the-phone recognition of those patients that are likely to quality as true emergencies,

and direct the client to bring the patient in for immediate care (Table 1). Most ill patients benet from transportation in a

small, dark container with the provision of gentle heat. Care must be taken with less heat tolerant species (guinea pigs,

chinchillas), and with patients who may be suffering from heat-related illness. Many clients have access to instant

chemical warming devices or hot water bottles. Other potential sources of warmth include a potato or dried beans in a

sock heated in the microwave.

Clients with patients who are actively bleeding should be instructed on how to safely restraint the animal and apply direct

pressure. If care is delayed, conscious patients able to swallow can benet from administration of small amounts of sugar

syrup diluted in water and administered by syringe or eyedropper.

Veterinary reception staff and technicians/nurses must be trained to visually identify the critical patient and admit it directly

into the hospital for immediate evaluation and care. (Table 1).

EXAMINATION OF THE CRITICAL PATIENT

Every exotic patient should be examined carefully from a distance before beginning restraint. Patients that are weak or in

respiratory distress should be transported back into the hospital for stabilization, and full physical examination delayed.

Some cursory information can be gleaned from these patients during placement into an oxygenated incubator. Quickly

access overall condition based on muscle mass. This information can help plan the next diagnostic or therapeutic step(chronic vs. acute illness).

In many cases, critical status becomes apparent during examination. Patients exhibiting any of these signs and symptoms

should be released immediately back to the examination table or enclosure, and steps taken for emergency stabilization:

increased respiratory effort and dyspnea, open-mouth breathing, especially in an obligate nasal breather (rabbits, guinea

pigs and many rodents), and increasing lethargy and weakness.

DECISION MAKING FOR THE CRITICAL PATIENT

In many cases, the clinician is faced with a number of difcult decisions. In any single case, aggressive emergency

procedures may result in the death of the patient. In contrast, failure to utilize aggressive emergency procedures may

result in the death of the patient.

The difcult job of determining which patients can tolerate aggressive therapy (placement of venous access, acquisition

of diagnostic testing) requires considerable experience and apparently in many cases, plain good fortune. In the authorsexperience, patients in critical condition due to long-term, chronic disease do not tolerate aggressive therapy, and benet

from a much more conservative approach, for example, 24 hours of heat, uids administered subcutaneously, antimicrobial

therapy is clearly indicated and support feeding. Patients with more acute disease conditions, for example, trauma, may

respond to a more aggressive therapeutic approach.

Angela M. Lennox, DMV, DABVP (Avian)

Avian and Exotic Animal Clinic, Indianapolis, Indiana

Oxbow Animal Health 29012 Mill Road Murdock, NE 684071-402-867-2400 1-800-249-0366 www.oxbowanimalhealth.com


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TREATMENT OF THE CRITICAL PATIENT

Airway Support

Patients in respiratory distress should be placed in a warmed oxygenated chamber. The author has found administration

of medications with anti-anxiety properties benecial in many cases (see Its Great to Sedate). These drugs work

synergistically to reduce anxiety with minimal respiratory depression.

Airway support for mammals in respiratory distress can be challenging. Intubation of ferrets and other carnivores is

performed as in a cat. Intubation of rabbits is considerably more difcult. Intubation techniques encompass a wide variety

of modalities beyond traditional orotracheal intubation, or introduction of a tube via the oral cavity into the trachea. Other

modalities include forced ventilation with a tight tting mask, nasal intubation, nasotracheal intubation, and direct tracheal

intubation via tracheostomy or temporary tracheostomy.1

Bronchodilators such as terbutaline at 0.01 mg/kg IM q6-8h can be effective in cases of suspected bronchoconstriction.

Cardiovascular Support

Vascular access in mammals can be performed via two routes: intravenous and intraosseous. IV catheterization in rabbits,

ferrets and similarly sized patients is straightforward, and is most commonly performed via the cephalic vein with 24-25 g

catheters. The author regular performs catheterization of larger guinea pigs and chinchillas but considers it more

challenging. Intraosseous catheterization is well described in exotic companion mammals, and can be performed in patients

as small as a mouse. Sites include the proximal tibia at the tibial crest, and the femur. The relatively soft bone cortex of

smaller mammals allows the use of standard injection needles as intraosseous catheters, and size ranges from 22 to 27 g.

Placement in much larger mammals can be facilitated with larger (22-18 g) injection or spinal needles.

Correct placement can be conrmed in several ways. Injection of uids into a correctly placed catheter does not result in

accumulation of uids into the associated soft tissues, with the exception of leakage of uids from the entry site into the

bone in a poorly seated catheter. Absolute conrmation may require evaluation of radiographs in two views.

The IO catheter can be capped with a standard IV injection cap and the catheter secured by taping it to the limb.

Studies in human patients indicate IO vascular access can be considered equivalent to IV access in terms of onset of action

of therapeutic agents, and time to establishment of peak drug levels. Recommendations for physicians include maintenance

of the catheter no more than 72 hours. Complications in humans are rare (less than 1%) and include local cellulitis and

infection, fracture, and leakage of administered drugs/uids into adjacent soft tissues.2,3 The author is unaware of a single

severe complication in an mammal patient after nearly 10 years of use of this technique in clinical practice, with the

exception of fracture of the tibial crest in a chinchilla, and temporary soft tissue swelling. Fluid choices, volume and rates

depend on patient condition and the goal of uid therapy. Fluids should be warmed appropriately prior to administration.

Hypovolemia

The patient in hypovolemic shock is usually weak and often unable to stand. Ultimate conrmation of the presence of

hypovolemia is documentation of below normal blood pressure. Treatment of hypovolemic shock has been described byLichtenberger, and relies on restoration of normal indirect systolic blood pressure.4 While difcult in very small patients,

acquisition of blood pressure is relatively easy in larger mammals. Assessment of blood pressure requires a sphygmometer,

pediatric cuff and an ultrasonic doppler. Placement requires practice. In most mammals, normal blood pressure is above

70 mm Hg. It should be kept in mind that a number of variables can affect blood pressure readings, and the best use may

be as a trend monitor. In other words, improvement of blood pressure in a mamal that progresses from weak to standing

and resisting is an indication of normovolemia, even if blood pressure readings do not exceed 70 mmHg. The author has

encountered numerous cases where blood pressure readings could not be obtained, but were readily detected after

initiation of uid therapy.

Fluid choices for hypovolemic shock include crytalloids (lactated Ringers and other similar solutions), and colloids (Hetas-

tarch, Braun Medical Inc.k Irvine CA; and Oxyglobin, Biopure, Cambridge MA). A suggested ow chart for uid resuscitation

is presented in Table 2.





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Dehydration

Dehydration decits are calculated after correction of hypovolemia, if present. Determination of percent dehydration is

determined using criteria as used in traditional mammals. Information can also be gleaned from PCV and measurement

of blood proteins.

Volume of uids for correction of dehydration is calculated using the formula: Volume (ml) = hydration decit x body weight

(kg) x 1000 ml. Add hydration decits to daily maintenance needs (3-4 ml/kg/h) and administer over 24 hours.4 It is also

useful to add projected ongoing losses (polyuria and vomiting) to the total as well. Ongoing needs are adjusted during

treatment, and re-evaluated after 24 hours.

Control of Hemorrhage

In most cases, effective clotting mechanisms and efcient compensatory mechanisms prevent fatal hemorrhage. However,

animals on sub-optimal diets or with other underlying illness may be more at risk.

Other common sources of bleeding include traumatic wounds (including self-trauma), supercial neoplasms and bleeding

from the gastrointestinal or reproductive tract.

Restoration of Normothermia

Measurement of body temperature can be problematic in small patients, but is enhanced with the use of small exible

temperature probes. Methods of active rewarming include forced air (incubator, Bair Hugger) and administration of

warmed intravenous uids.

Table 1. Selected signs and symptoms commonly associated with the critical avian patient




Sign/Symptom CommentsActive bleeding

Respiratory distress

Seizure

Depression Often exhibited as non-interest in surroundings

Weakness Especially laterally recumbency


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Table 2. Flow chart for uid resuscitation of the patient with hypovolemia and shock, and subsequent calculation of uids

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References:

Lennox A. Intubation of Exotic Companion Mammals. J Exotic Pet Med, in print, 2008.

Buck ML. Intraosseous administration of drugs in infants and children. Pediatr Pharm 12(12), 2006. Medicine Journal (serial online) 2008. Available at

http://www.medscape.com/viewarticle/552022 Accessed 4/08.

Tein Tay E, Hafeez W. Intraosseous access. EMedicine Journal, 2008. Available at http://www.emedicine.com/proc/TOPIC80431.HTM. Accessed 4/08.

Lichtenberger M. (2007) Shock and cardiopulmonary-cerebral resuscitation in small mammals and birds. Vet Clin Exot Anim 10:275-291.

Reprinted in part from the Proceedings of the Kentucky Veterinary Medical Association Annual Conference, 2008.

Step Comments

Determine starting blood pressure,

and measure periodically throughout

treatment

Use starting number as a baseline and monitor trends during treatment. Due to

numerous factors, actual numbers may vary signicantly from those reported

in the literature. Note that in severely hypovolemic patient, BP may not initially

be detected.

Administer Crystalloids 10 ml/kg IV or IO 1-2 boluses

Administer Colloids(Hetastarch, Oxyglobin)

3-5 ml/kg IV or IO over 10 minutes 1-2 boluses

If patient condition and BP

measurements are not improving:

Administer third dose of cystalloids and colloids.

If no improvement: Administer Oxyglobin at 5 ml/kg IV or IO 1-2 boluses

If Oxyglobin unavailable: Administer hypertonic saline 7.5% a 5 ml/kg bolus slowly over 10 minutes,

followed by crystalloids

If no improvement: Continue uid administration via infusion pump and monitor for response to

therapy

Once normovolemia is established,

calculate hydration decits

V (ml) = hydration decit x body weight (kg) x 1000 ml.

Add daily maintenance needs 3-4 ml/kg/hAdd to total estimated ongoing

losses in excess of normal

Losses can stem from polyuria or regurgitation; ideally, these should be

measured and added to the calculation.

Administer total over 24 hours and

then re-evaluate

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