Urethral Deobstruction In Cats

Discussion in 'Veterinary Discussion' started by Admin, Jul 17, 2017.

By Admin on Jul 17, 2017 at 4:52 PM
  1. Admin

    Admin Administrator Staff Member

    Edward Cooper, VMD, MS, DACVECC, The Ohio State University, College of Veterinary Medicine

    Urethral obstruction is a potentially life-threatening manifestation of feline lower urinary tract disease that requires immediate medical intervention. Following are recommendations and guidelines for urethral deobstruction in cats, with an emphasis on the importance of minimizing urethral trauma because tearing or stricture formation can increase patient morbidity and mortality and add to treatment costs.1

    Anesthesia Protocol
    A protocol for managing urethral obstruction without the use of a urethral catheter (as an alternative to euthanasia) has been described in the literature,2 but management of urethral obstruction through placement of a urethral catheter is still the standard of care.

    Initial stabilization includes placement of an IV catheter and initiation of fluid therapy. To optimize urethral catheter placement and minimize damage to the urethra, administer analgesia and sedation or anesthesia. For unstable patients (ie, those with electrolyte abnormalities and/or respiratory or cardiovascular compromise), administration of only light sedation should be sufficient. Patients with stable vital signs may receive higher sedative dosesor be placed under general anesthesia. All patients should receive pain medication. A novel method of pain control using a coccygeal epidural block may also be beneficial in these patients and can be considered.3

    • Anesthesia Protocols for Urethral Deobstruction*

      Patients with normal mentation & physical parameters

    • Ketamine (5-10 mg/kg IV or IM) + diazepam or midazolam (0.25-0.5 mg/kg IV or IM)
    • Buprenorphine (0.01-0.02 mg/kg IV or IM) + acepromazine (0.03-0.05 mg/kg IV or IM) or diazepam/midazolam (0.25-0.5 mg/kg IV or IM)
      Coccygeal epidural3
    • Lidocaine 2% (0.1-0.2 mL/kg)
    • Propofol (1-4 mg/kg IV, to effect)
    • Inhalant anesthesia (eg, isoflurane, sevoflurane)
      Patients with electrolyte abnormalities and/or cardiovascular or cardiorespiratory compromise

      Sedation/analgesia only
    • Buprenorphine (0.01-0.02 mg/kg IV or IM) + diazepam or midazolam (0.25-0.5 mg/kg IV or IM)
    • Methadone (0.2-0.25 mg/kg IV or IM) + diazepam or midazolam (0.25-0.5 mg/kg IV or IM)
      Coccygeal epidural3
    • Lidocaine 2% (0.1-0.2 mL/kg) administered into the sacrococcygeal epidural space
      *Protocols preferred by the author
    Vocalization or movement during catheterization indicates insufficient sedation and is more likely to be associated with significant urethral spasm and increased risk for urethral trauma. In these patients, administer higher doses of medications or provide additional analgesics and/or sedatives. Less experienced clinicians may prefer using general anesthesia because it provides longer sedation than injectable medications, allowing more time to complete the procedure. Whether using sedation or anesthesia with intubation, the patient should be monitored (eg, ECG, blood pressure, pulse oximetry) commensurate with clinical status/instability and standard of care.

    FIGURE 1 Urinary catheters may be made of polypropylene (A), polyvinyl (B), polytetrafluoroethylene (C), and polyurethane (D). Polyvinyl catheters are not open-ended and therefore not typically used for unblocking but can be placed long-term. Polypropylene catheters are not suitable for longterm placement because of their potential to irritate. Photos courtesy of Edward Cooper, VMD, MS, DACVECC

    Catheter Type & Size
    An open-ended catheter made of polypropylene, polytetrafluoroethylene, or polyurethane is typically used to relieve the obstruction. (See Figure 1.) Polypropylene catheters are the most rigid, which may make them more effective in relieving an obstruction; however, they are more likely to cause urethral trauma, especially if excessive force is used during placement. Because polypropylene catheters can also be more reactive and irritating,4 they should not be left in place for ongoing management.

    Polytetrafluoroethylene and polyurethane catheters are firmer at room temperature, which facilitates initial unblocking efforts, and they soften when warmed to body temperature, which allows them to be left in place. Placing one catheter that can be used both for deobstruction and ongoing management may cause less urethral trauma.

    Consider catheter size when selecting the type of catheter for deobstruction. One retrospective study found that patients unblocked with a 5Fr catheter compared with a 3.5Fr catheter had increased risk for reobstruction within 24 hours (19% vs 6.7%, respectively), which suggested a benefit in using a smaller catheter; however, the potential for confounding factors to have affected the results is significant.5 Another study failed to find an association with catheter size and risk for reobstruction.6These results suggest the impact of catheter size is unclear.

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Discussion in 'Veterinary Discussion' started by Admin, Jul 17, 2017.

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