Monitoring Spinal Cord Tissue Oxygen in Patients With Acute, Severe Traumatic Spinal Cord Injuries

Abstract

Objectives: To determine the feasibility of monitoring tissue oxygen tension from the injury site (p_sctO₂) in patients with acute, severe traumatic spinal cord injuries. Design: We inserted at the injury site a pressure probe, a microdialysis catheter, and an oxygen electrode to monitor for up to a week intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), tissue glucose, lactate/pyruvate ratio (LPR), and p_sctO₂. We analyzed 2,213 hours of such data. Follow-up was 6–28 months postinjury. Setting: Single-center neurosurgical and neurocritical care units. Subjects: Twenty-six patients with traumatic spinal cord injuries, American spinal injury association Impairment Scale A–C. Probes were inserted within 72 hours of injury. Interventions: Insertion of subarachnoid oxygen electrode (Licox; Integra LifeSciences, Sophia-Antipolis, France), pressure probe, and microdialysis catheter. Measurements and Main Results: p_sctO₂ was significantly influenced by ISP (p_sctO₂ 26.7 ± 0.3 mm Hg at ISP > 10 mmHg vs p_sctO₂ 22.7 ± 0.8 mm Hg at ISP ≤ 10 mm Hg), SCPP (p_sctO₂ 26.8 ± 0.3 mm Hg at SCPP < 90 mm Hg vs p_sctO₂ 32.1 ± 0.7 mm Hg at SCPP ≥ 90 mm Hg), tissue glucose (p_sctO₂ 26.8 ± 0.4 mm Hg at glucose < 6 mM vs 32.9 ± 0.5 mm Hg at glucose ≥ 6 mM), tissue LPR (p_sctO₂ 25.3 ± 0.4 mm Hg at LPR > 30 vs p_sctO₂ 31.3 ± 0.3 mm Hg at LPR ≤ 30), and fever (p_sctO₂ 28.8 ± 0.5 mm Hg at cord temperature 37–38°C vs p_sctO₂ 28.7 ± 0.8 mm Hg at cord temperature ≥ 39°C). Tissue hypoxia also occurred independent of these factors. Increasing the FIO₂ by 0.48 increases p_sctO₂ by 71.8% above baseline within 8.4 minutes. In patients with motor-incomplete injuries, fluctuations in p_sctO₂ correlated with fluctuations in limb motor score. The injured cord spent 11% (39%) hours at p_sctO₂ less than 5 mm Hg (< 20 mm Hg) in patients with motor-complete outcomes, compared with 1% (30%) hours at p_sctO₂ less than 5 mm Hg (< 20 mm Hg) in patients with motor-incomplete outcomes. Complications were cerebrospinal fluid leak (5/26) and wound infection (1/26). Conclusions: This study lays the foundation for measuring and altering spinal cord oxygen at the injury site. Future studies are required to investigate whether this is an effective new therapy.