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Updated: Sep 24, 2025
Optic Nerve Sheath Point of Care Ultrasound: Image Acquisition
Published on: August 18, 2023
Relation between partial arterial carbon dioxide pressure and pH value and optic nerve sheath diameter: a prospective
1Department of Emergency Medicine, Emergency Medicine Specialist, Antalya Training and Research Hospital, Varlik District, Kazim Karabekir Street, 07100, Antalya, Turkey. drmuratduyan@gmail.com.
Objective:
This study aims to determine if there is a correlation between differences in optic nerve sheath diameter (ONSD) and changes in PaCO2 and pH values that were measured in the arterial blood gas (ABG) before and after treatment in COPD patients with acute hypercarbic respiratory failure (AHRF).
Materials And Methods:
This study serves as a prospective self-controlled non-randomized trial study conducted in the emergency clinic of a tertiary hospital. Forty-four patients with COPD, who were found to have acidosis and hypercarbia in ABG and had an indication for non-invasive mechanic ventilation (NIMV), were analyzed prospectively. Demographic information, vital findings, initial ABG values, the ONSD measurement (before the NIMV treatment), consciousness state, and the ABG results obtained in the second hour of the monitoring and the ONSD measurement (after the NIMV treatment) were recorded.
Results:
In this study, 13 (29.5%) of the patients were female and 31 (70.5%) were male. The age distribution was evaluated as 68.3 ± 9.2 years; the minimum age was 54 and the maximum was 91. A high level of positively significant correlation was found between the mean ONSD and PaCO2 (p < 0.0001). There is a high fit (0.72) between the mean ONSD and PaCO2. A moderate level of negatively significant correlation was found between the mean ONSD and the pH (p < 0.0001). However, there is an insignificant low fit (0.32) between the mean ONSD and the pH.
Conclusion:
The ONSD changed significantly and in a highly correlated manner to acute changes in PaCO2 levels.
