This is a retrospective chart review of patients undergoing spinal fusion surgery to see the prevalence of hyperventilation.

Retrospective review of the operative schedules to identify patients who have undergone spinal fusion with placement of an arterial cannula for intermittent arterial blood gas analysis. The intraoperative records will be retrospectively reviewed. The following demographic data will be recorded: age, weight, gender, and co-morbid medical conditions. Ventilatory parameters at the time of ABG analysis will include (respiratory rate and tidal volume). ABG data will be collected.

Inclusion Criteria:

• Patients who underwent complex surgical procedures (spinal fusions) which necessitated arterial line placement and intermittent arterial blood gas analysis

Exclusion Criteria:

• None

Spinal fusion patients