Resumen

RAMIREZ U, Ricardo A et al. Cardiorespiratory effects and isoflurane requirements in rabbits subjected to ophthalmologic surgery treated with tramadol pre-, intra- or postoperatively. Rev. Fac. Cienc. Vet. [online]. 2013, vol.54, n.1, pp.3-10. ISSN 0258-6576.

To evaluate the cardiorespiratory effects and isoflurane requirements of tramadol applied at different times during ophthalmic surgery, a blind prospective study was made in 24 rabbits, randomly divided into three groups of eight subjects each: pre-operatory tramadol group (Tpre), trans-operatory tramadol group (Ttrans) and post-operatory tramadol group (Tpos), which received three intramuscular injections of equal volume, in the pre, intra and post-operative period, containing tramadol hydrochloride (4 mg/kg) or NaCl 0,9%, according to each group. Anesthetic induction and maintenance was made with isoflurane diluted  FiO2 1.0. Once the anesthetic plane was stabilized, surgical procedure was started. Were evaluated heart rate (HR), medium arterial presseure (MAP), respiratory rate (f), end tidal CO₂ (EtCO₂), Oxihemoglobin saturation (SpO₂) and end tidal isoflurane (EtISO). Variables were measured after anesthesia stabilization (m1) and every 10 min after onset of surgery, until the end of experimental protocol (m10 to m40). HR, SpO₂, f, EtCO₂ and EtISO were similar among groups at all times. MAP were significantly higher (p<0.01) in m1 than in other moments and Tpre group showed lower (p=0.04) values than the other groups at this moment. Tramadol hydrochloride promotes transient reduction of blood pressure in isoflurane anesthetized rabbits subjected to ophthalmic surgery. The preoperative administration of the drug does not reduce the anesthetic requirement and results in a more pronounced hypotension. Additionally, isoflurane anesthesia, associated to oculocardiac reflex generates a hypotension phenomenon that must be taken in to considertation during ophthalmologic surgeries.

Palabras clave : Blood pressure; isoflurane; cardiovascular system; oculocardiac reflex; tramadol.

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