Noninvasive Measurement of Oxygen Saturation in Human Retinal Blood Vessels and Tissues With Multispectral Confocal Imaging.

BACKGROUND AND OBJECTIVE: Proof of concept for the first system of noninvasive human retinal vessel and tissue oxygenation measurement in axial and radial directions. MATERIALS AND METHODS: A confocal imaging system capable of calculating and mapping relative retinal blood oxygenation in radial and axial directions from three eyes of two healthy subjects was built. The relationship between oxygenation and retinal depth in vivo was analyzed to illustrate application of this novel system. RESULTS: The system shows capacity for measuring oxygenation along retinal depth for the first time. (1) Arteriovenous oxygenation difference decreases with blood vessel diameter. (2) Artery-tissue oxygenation difference is greater than vein-tissue oxygenation difference in the same region. (3) Intravascular-extravascular oxygenation difference decreases with blood vessel diameter. (4) Oxygenation data reported with a 95% CI are as follows: A1 91.5% ± 18.2%, V1 32.8% ± 18.6%, A2 97.3% ± 17.8%, V2 64.4% ± 11.2%, A3 73.2% ± 19.1%, V3 52.9% ± 15.3%, and Tissue 56.6% ± 00.4%. CONCLUSION: This article demonstrates proof of concept for retinal oxygenation calculation in radial and axial dimensions for the first time. Initial results provide biological validity to this method. Future aims include further characterization of this system's results in healthy subjects and subsequent comparison of oxygenation between diseased and healthy retinae. [Ophthalmic Surg Lasers Imaging Retina. 2022;53:275-283.].

Dramatic Reduction in Opioid Prescribing for Common Outpatient Orthopaedic Lower Extremity Surgical Procedures at a Louisiana University-Based Safety-Net Hospital After Enactment of Opioid-Limiting State Legislation.

INTRODUCTION: The opioid epidemic in the United States has been fueled by overprescribing opioids, which is particularly apparent in orthopaedics. Stakeholders, including state legislatures, have attempted to curb opioid overprescribing to reduce related abuse/dependence, overdose deaths, and diversion. OBJECTIVE: To examine trends in opioid prescribing for common outpatient lower extremity orthopaedic surgeries in a population vulnerable to prolonged opioid use before and after the enactment of a 2017 Louisiana state law limiting opioid prescribing for acute pain. METHODS: Eligible patients were adults who underwent one of the five most common outpatient lower extremity orthopaedic surgeries done during 2013 to 2018 at an urban tertiary care academic medical center. Excluded were prisoners and patients who required inpatient hospitalization, had no documented discharge opioid prescription, or filled an opioid prescription unrelated to their orthopaedic procedure within 30 days before surgery. RESULTS: During 2013 to 2018, 655 surgical procedures were done in 655 eligible patients, of whom 49% were Black and 54% were insured by Medicaid. The mean morphine milligram equivalent per discharge prescription decreased by almost 70% from 2014 to 2018. A statistically significant decrease in the mean morphine milligram equivalent per discharge prescription was observed in 2018 versus all previous years (P < 0.0001 for all) and in 2017 versus all previous years (P < 0.0001 for all). Patients receiving at least one new opioid prescription after their discharge prescription declined over time from a high of 50% in 2013 to a low of 19.3% in 2018 with a statistically significant effect over time (P < 0.0001). DISCUSSION: Opioid prescribing for patients undergoing common outpatient lower extremity orthopaedic surgeries who were at high risk for prolonged opioid use markedly declined after the enactment of a state law limiting first-time opioid prescriptions to 7 days, requiring physicians to check the state's Prescription Monitoring Program database and mandating continuing education for opioid prescribers.