Low blood pressure during anesthesia and recovery in paraplegic dogs

Abstract

OBJECTIVE To evaluate the effect of anesthesia-associated hypotension on final motor and urinary function in paraplegic dogs without nociception that underwent hemilaminectomy because of acute, severe thoracolumbar intervertebral disk herniation (IVDH). DESIGN Retrospective case series. ANIMALS 56 paraplegic dogs with acute thoracolumbar IVDH and absent nociception. PROCEDURES Medical records were reviewed, and signalment, history, anesthetic details, and results of serial neurologic assessments performed for at least 4 weeks after surgery were recorded. Motor function was retrospectively scored with a 5-point scale, and urinary function was scored with a 3-point scale. Hypotension was defined as MAP ≤ 60 mm Hg or SAP ≤ 80 mm Hg for at least 2 consecutive readings 5 minutes apart. Associations between hypotension and outcome were assessed by use of the Fisher exact test. RESULTS Thirty-three (59%) patients experienced hypotension during anesthesia. Thirty-four (61%) patients (20/33 with and 14/23 without hypotension) regained ambulation. Whether dogs regained motor or urinary function was not significantly associated with the occurrence of hypotension (P = 0.35 and P = 0.86, respectively), the duration of hypotension (P = 0.213 and P = 0.274), or the lowest blood pressure recorded (P = 0.556 and P = 0.699). CONCLUSIONS AND CLINICAL RELEVANCE For this group of dogs undergoing hemilaminectomy because of acute, severe thoracolumbar IVDH, anesthesia-associated hypotension was not significantly associated with whether dogs regained motor or urinary function after surgery. However, normotension should be the goal in all patients with spinal cord injuries, especially patients undergoing general anesthesia.