Nitrous oxide
Nitrous oxide (N2O) is an inhalational gas used in combination with oxygen to carry volatile anaesthetic agents (such as isoflurane) for the induction and maintenance of general anaesthesia. It reduces the required concentration of the primary inhalant agent and hastens the attainment of a stable anaesthetic plane via the **second gas effect** and **concentration effect**. > **Clinical Warning:** N2O will cause a rapid expansion of any gas-filled space, increasing volume or pressure. It is strictly contraindicated in patients with pneumothorax or gastric dilatation-volvulus (GDV). > **Clinical Warning:** Oxygen must be supplemented for 5-10 minutes after N2O is discontinued to prevent **diffusion hypoxia**.
Mecanismo: Nitrous oxide causes generalized **CNS depression**. When administered at the beginning of volatile agent anaesthesia, it increases the speed of uptake of the volatile agent from the alveoli → **second gas effect** and **concentration effect** → hastens attainment of a stable plane of anaesthesia. It has minimal direct respiratory and cardiovascular effects.
Dosificación por especie
- Adjunct for induction and maintenance of anaesthesia · Inspired concentrations of 50-70% · Inhalational · Continuous during anaesthesia · Duration of procedure · Must be administered with a minimum of 30% oxygen.
- Adjunct for induction and maintenance of anaesthesia · Inspired concentrations of 50-70% · Inhalational · Continuous during anaesthesia · Duration of procedure · Must be administered with a minimum of 30% oxygen.
Las dosis son una referencia clínica para médicos veterinarios. Confirme siempre con la información vigente del producto y el paciente individual.
Vías de administración
Contraindicaciones
- Patients with air-filled spaces within the body (e.g., pneumothorax, gastric dilatation/GDV, intestinal obstruction)
- Marked respiratory compromise (due to hypoxia risks)
- Raised intracranial pressure (due to associated increases in cerebral blood flow)
Efectos adversos
- Diffusion hypoxia (if oxygen is not supplemented upon discontinuation)
- Megaloblastic changes in bone marrow (with exposure lasting a few hours)
- Agranulocytosis (with prolonged exposure of a few days)
Monitoreo
- Inspired oxygen concentration (FiO2) - especially in rebreathing circuits
- Pulse oximetry (SpO2)
- Capnography (ETCO2)
- Respiratory rate and effort
- Cardiovascular parameters (HR, BP)
Sobredosis
Overdosage primarily presents as **hypoxia** if the inspired oxygen concentration falls below 30%. Treatment consists of immediately discontinuing nitrous oxide and providing 100% oxygen via positive pressure ventilation if necessary.
La referencia de fármacos de VetSheet está destinada a médicos veterinarios como apoyo a la decisión clínica; no sustituye el juicio profesional ni la información vigente del fabricante.