Page 448 - Cote clinical veterinary advisor dogs and cats 4th

198 Coma and Stupor

TREATMENT Supportive care: PROGNOSIS & OUTCOME
• Control seizures (p. 903): • Varies with underlying disease
Treatment Overview
VetBooks.ir Coma has numerous causes. Initial therapy twice in 15 minutes. If ineffective, use • Generally guarded until diagnosis confirmed
○ Diazepam 0.5-1 mg/kg IV; can repeat
constant-rate infusion or different drug,
should focus on stabilization of the cardiovas-
• Declines as level of consciousness decreases
or
cular (perfusion), respiratory (oxygenation and
• Unresponsive pupils, decerebrate rigidity,
ventilation), and neurologic (cerebral oxygen ○ Phenobarbital 2-15 mg/kg slow IV bolus • Worse with systemic complications
delivery and ICP) systems, followed by specific (monitor respiration), or abnormal respiratory patterns, and loss
therapy tailored to the underlying cause. ○ Propofol (if severe hepatopathy/hepatic of physiologic nystagmus carry a grave
coma) 1-6 mg/kg IV bolus, can repeat or prognosis.
Acute General Treatment switch to constant-rate infusion (monitor • Miotic responsive pupils suggest cortical
Airway and breathing: respiration) lesions and a better prognosis.
• Endotracheal intubation assists ventilation ○ Levetiracetam 20-30 mg/kg IV, may • Hypoglycemia due to insulin overdose has
and protects the airways (comatose patients repeat a good prognosis.
cannot swallow; salivary secretions, regur- • Treat hypoglycemia with 0.5 g/kg IV dextrose • Can use modified Glasgow coma scale for
gitation, and vomiting may cause airway (p. 552). prognosis in dogs with head trauma (p. 404).
obstruction and aspiration pneumonia). ○ Dilute 1 mL/kg of 50% dextrose in 3 • Failure to improve over 5-7 days warrants
Avoid inducing cough, which increases ICP. × volume of 0.9% saline for slow IV poor prognosis.
• Provide supplemental oxygen (maintain PaO 2 administration to avoid injury due to
> 60 mm Hg, SaO 2 > 90%) (p. 1146). hyperosmolar fluid infusion (e.g., for 2 kg PEARLS & CONSIDERATIONS
○ CAUTION: nasal oxygen lines can induce dog, dilute 2 mL of 50% saline in 6 mL
sneezing, which increases ICP. saline). Comments
• Ensure ventilation (maintain PCO 2 between ○ Avoid hyperglycemia. • Animals that display decerebrate rigidity are
35 and 45 mm Hg). • Glucocorticoids (e.g., methylprednisolone also comatose.
Circulation: sodium succinate 30 mg/kg IV initial • Cranial nerve reflexes (depending on location
• Place intravenous catheter (avoid jugular dose, then according to standard proto- of the lesion) and spinal reflexes are often
veins if ICP elevated). cols, or dexamethasone 0.1 mg/kg IV) present.
• Correct hypovolemia. may be beneficial (neoplasia) or harmful • Bradycardia with concurrent hypertension
○ Fluid choice is controversial. (trauma). suggests elevated ICP.
Crystalloids usually sufficient. Admin- ○ Try to confirm diagnosis before giving • Can use caloric test to evaluate nystagmus
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ister 1 4 shock dose (15 mL/kg in dogs; glucocorticoids. (infusion of warm or cold water into the ear
10 mL/kg in cats) rapidly intravenous ○ If life-threatening deterioration occurs canal normally results in nystagmus).
(IV); repeat as needed for cardiovascular before the diagnosis is confirmed, rapid- • Administration of lidocaine during intuba-
stability. acting intravenous glucocorticoids can be tion (0.75 mg/kg IV) may suppress gag
Hypertonic saline (5%-7.5% at administered for suspected neoplasia or and cough reflexes, which would otherwise
■
4-6 mL/kg over 10 minutes) may encephalitis. increase ICP.
decrease ICP while improving perfu- Specific therapy: see specific diseases.
sion. Avoid in hyperosmolar syndromes, Technician Tips
hyponatremia, heart failure, and marked Possible Complications • Physical therapy, turning to change
dehydration. • Hypotension recumbencies, lubrication of the eyes, and
○ Avoid overhydration. • Hypothermia moistening the mouth every 4 hours are
• Provide maintenance fluids, and replace • Brain herniation important elements of support for comatose
ongoing fluid losses. • Cardiac arrhythmias patients.
• With cardiac disease or hyperosmolar • Hypoventilation • A urinary catheter assists with monitoring
syndromes, administer any fluids cautiously. • Aspiration pneumonia urine output and preventing urine scald.
Address (i.e., reduce) ICP: • Seizures
• In comatose patient, assume ICP elevated Client Education
until proved otherwise. Recommended Monitoring • Full neurologic recovery can take weeks to
• Elevate head 20-30 degrees. Rapid deterioration possible: monitor until months.
• Avoid pressure on jugular veins. stable and improving. • Long-term neurologic deficits and seizures
• Give mannitol (0.5-2 g/kg IV over 20-30 • Neurologic examination every 30-60 minutes can occur.
minutes) if diagnosis is unconfirmed or • Continuous electrocardiogram
patient shows neurologic deterioration. • Blood pressure every 30-60 minutes (systolic: SUGGESTED READING
• Avoid mannitol in dehydrated, hypovolemic > 90 mm Hg but < 180 mm Hg; mean, Parratt CA, et al. Retrospective characterization of
patients and when underlying cardiac disease > 60 mm Hg but < 140 mm Hg) coma and stupor in dogs and cats presenting to a
or hyperosmolar states are present. • Blood gases (PaCO 2 and PaO 2 ) every 60 multicenter out-of-hours service (2012-2015):386
• Hypertonic saline (5%-7.5% at 4-6 mL/ minutes or capnography and pulse oximetry animals. J Vet Emerg Crit Care 28, 2018. https://
kg over 10 minutes) may be advantageous continuously doi.org/10.1111/vec.12772.
for traumatic brain injury. Can be repeated. • Blood glucose and electrolytes as needed AUTHOR: Søren R. Boysen, DVM, DACVECC
Sodium concentration should be monitored EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
(aim for 10-15 mEq/L above upper reference
value).

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