1. Intraperitoneal and Incisional Anesthesia

Incisional anesthesia is accomplished by infiltrating the skin in the surroundings of the surgical field with local anesthetics. For laparotomy, local anesthetics are injected into the subcutaneous tissues along the linea alba before celiotomy.

Intraperitoneal anesthesia with bupivacaine produces postoperative analgesia in cats undergoing an ovariohysterectomy¹; plasma concentrations of bupivacaine were below toxic levels.² For ovariohysterectomy, the solution of bupivacaine 0.5% (2 mg/kg) is diluted with an equal volume of saline 0.9% resulting in a final concentration of 0.25%. Otherwise, commercial formulations of bupivacaine 0.25% are available. The final solution is equally divided in three parts and instilled into the peritoneal space over the ovarian pedicles and caudal uterus using a 3-ml syringe. The solution is prepared sterilely. Videos will be presented to describe these techniques.

2. Supraglottic Airway Devices

Supraglottic airway devices are good options for airway management in cats. The device comprises a tube with a distal elliptical component that has an inflatable bladder on the dorsal aspect that is used when needed to create a better seal. Intubation is easy and well performed by individuals with little experience in feline airway management. A lower incidence of upper airway discomfort after extubation when compared with an endotracheal tube. They can be inserted at a more superficial depth of anesthesia than an endotracheal tube and used for mechanical ventilation.³ However, the author does not use in dental procedures due to the risk of accidental extubation. A capnograph is recommended to avoid complications. These devices are much more expensive than endotracheal tubes. This lecture will present a quick guide and evidence behind the use of these devices.

3. Pulse Oximetry and Capnography

Pulse oximeters are insensitive monitors that give rapid and continuous assessment of the pulse rate. SpO₂ (i.e., measurement of hemoglobin saturation) values correlate with PaO₂ (i.e., partial pressure of oxygen). Values that are lower than 90% indicate hypoxemia which will have deleterious effects in the body with potential cardiovascular collapse.

Capnographs are devices used to measure the end-tidal volume of carbon dioxide during anesthesia, and it is an indirect representation of partial pressure of carbon dioxide (PaCO₂) and represents the ventilatory status of the patient. The use of these two monitors in anesthesia decrease the risk of anesthetic-induced death dramatically.⁴ This lecture presents some practical considerations on the use of these two monitors.

4. Dexmedetomidine

Dexmedetomidine is an agonist of alpha-2 adrenergic receptors that produce sedation, muscle relaxation and chemical restraint. Lower doses are used for premedication especially in combination with opioid analgesics. Higher doses are used for sedation and chemical restraint especially in fractious animals or when immobility is required for radiographs and lancing of abscesses. The drug has also been administered in the early postoperative period to control dysphoria. It smooths anesthetic recovery in healthy patients when administered at 0.5–1 µg/kg IV. In cats, dexmedetomidine can be given by the buccal route of administration (oral transmucosal) for hands-off, off-label sedation.

5. Gabapentin

Gabapentin is a lipophilic structural analogue of the inhibitory neurotransmitter GABA. The mechanism of action of gabapentin remains to be elucidated, but the drug acts on voltage-gated calcium channels. This lecture will introduce some new insights in the administration of gabapentin for the treatment of acute pain and for transportation to veterinary visits in cats.⁵

References

1.  Benito J, Monteiro B, Lavoie AM, et al. Analgesic efficacy of intraperitoneal administration of bupivacaine in cats. J Fel Med Surg. 2016.

2.  Benito J, Monteiro BP, Beaudry F, et al. Pharmacokinetics of bupivacaine after intraperitoneal administration to cats undergoing ovariohysterectomy. Am J Vet Res. 2016;77:641–645.

3.  Prasse SA, Schrack J, Wenger S, et al. Clinical evaluation of the v-gel supraglottic airway device in comparison with a classical laryngeal mask and endotracheal intubation in cats during spontaneous and controlled mechanical ventilation. Vet Anaesth Analg. 2016;43:55–62.

4.  Brodbelt D. Feline anesthetic deaths in veterinary practice. Top Companion Anim Med. 2010;25:189–194.

5.  van Haaften KA, Forsythe LRE, Stelow EA, Bain MJ. Effects of a single preappointment dose of gabapentin on signs of stress in cats during transportation and veterinary examination. J Am Vet Med Assoc. 2017;251:1175–1181.