Postoperative Opioid and Respiratory Depression in Opioid Naive and Chronic Opioid Patients

Inclusion Criteria: * Patients from studies WARD Surgery Observational \[gov: NCT03491137\] * The control group from WARD Surgery Randomized Controlled Trial \[gov: NCT04640415\] Exclusion Criteria: * Less than 30 minutes of continuous monitoring data within the 60-minute window prior to opioid administration * Less than 120 minutes (\<50% of theoretical maximum) of monitoring data available during the four-hour observation period * Patients who received transdermal fentanyl as postoperative opioid * Patients with a baseline saturation or respiratory rate below the prespecified thresholds * Patients with a BMI of ≥40 or diagnosed with COPD were excluded in the analysis of SpO2 \<92%