Anesthesia Rounds 3 Flashcards
2) What is the normal end-tidal CO2 range?
3) How does the PaCO2 relate to the ETCO2
4) In which anesthetized cases would an increase in ETCO2
be contra-indicated. Why?
Small increases in CO2 may support sympathetic tone overall and may cause an increase in HR, BP in veterinary species. However, monitoring of ETCO2 in combination with RR and depth of ventilation is key to ensure levels are not too high resulting in significant respiratory acidosis.
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Contraindications to hypercarbia
1) Some of our veterinary patients may have tachyarrhythmias and thus hypercarbia would be a relative contraindication in veterinary medicine. That means if your patient is already tachycardic and has premature ventricular contractions as you might see commonly in a GDV, then making sure you monitor and assist ventilation is important (plus the metabolic acidosis and bloat in this patient would necessitate assisted ventilation).
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2) If the animal already has a metabolic acidosis from its primary condition, hypercarbia and resultant metabolic acidosis is not ideal. This could be any dehydrated, septic, sick patient requiring general anesthesia.
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Absolute contraindications for hypercarbia
1) increased intracranial pressure
2) increased intra-ocular pressure
3) significant metabolic acidosis
4) tachyarrhythmias and heart disease
Absolute contraindications for hypercarbia
5) If the ETCO2 value is significantly increased (>50- 55/57 mmHg) in an elective ASA 1-2 case – what should you do?
Hypocarbia
Hyperventilation - decrease in ETCO2
Causes: increase in RR, increase in tidal volume, decrease in metabolic rate or dramatic hypothermia
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TREATMENT – check animal and anesthetic depth, check other cardiorespiratory parameters, note timeline of administration of opioids or other analgesics, check temperature. Administer additional analgesics and increase inhalant if increase in RR fits with other increasing parameters and is the result of excessive surgical stimulation.
