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ANESTHETIC MONITORING: YOUR QUESTIONS ANSWERED |
Saved by Monitoring Case 2: Feline Cystolithiasis
EVALUATION History: A 12-year-old, 3.8-kg domestic shorthair cat presented with bladder stones.
Physical Examination: The cat was alert with strong femoral pulses; heart and lung sounds were within normal limits.
Blood Analysis: Packed cell volume, 38%; total protein, 7.6 g/dL; glucose, 125 mg/dL.
Imaging & Diagnosis: Radiographic assessment revealed multiple uroliths within the bladder. Treatment: Cystotomy was scheduled for bladder stone removal.
ANESTHETIC MONITORING
Anesthetic Protocol: UÊPremedication with midazolam (0.4 mg/kg IM) and hydromorphone (0.1 mg/kg IM) UÊInduction with propofol (3 mg/kg IV) UÊMaintenance with isoflurane to effect
Blood Pressure Monitoring during Anesthesia: Oscillometric blood pressure monitoring was performed.
Monitor Warning: While the cat underwent surgical preparation, its blood pressure and heart rate decreased (10 minutes after induction).
Vital Signs of Anesthetized Patient (Ten Minutes After Induction)
Systolic blood pressure (mm Hg) Diastolic blood pressure (mm Hg) Mean blood pressure (mm Hg) Heart rate (beats/min)
Respiratory rate (breaths/min) Oxygen level in blood (SpO2) (%) End tidal CO2 (mm Hg)
Temperature (°F)
69 51 57 95 16
100 38
100.3 Diagnosis: Isoflurane-induced hypotension and hydromorphone-induced bradycardia
Correction: UÊBalanced electrolyte fluids (Plasma-Lyte A, baxter.com) were maintained at 10 mL/kg/H. UÊThe isoflurance percentage was already low (1.25%); lowering it any further may have allowed the cat to awake prematurely.
UÊAn anticholinergic, glycopyrrolate (0.005 mg/kg, IV titration), was administered until the targeted heart rate was reached (normal parameter, 120–160 beats/min) and blood pressure improved (mean blood pressure, 70–90 mm Hg).
Pertinent Vital Signs
(Three Minutes after Glycopyrrolate Administration) Systolic blood pressure (mm Hg) Diastolic blood pressure (mm Hg) Mean blood pressure (mm Hg) Heart rate (beats/min)
96 67 77
120
Take-Home Message: Monitoring both heart rate and blood pressure simultaneously provided a useful tool to pharmacologically manipulate the heart rate in order to maintain proper blood pressure in this cat.
January/February 2012 Today's Veterinary Practice 27