Korean J Anesthesiol.  2014 Oct;67(4):240-245. 10.4097/kjae.2014.67.4.240.

Dynamic optic nerve sheath diameter responses to short-term hyperventilation measured with sonography in patients under general anesthesia

• Kim JY
• Min HG
• Ha SI
• Jeong HW
• Seo H
• Kim JU

• KMID: 1937682
• DOI: http://doi.org/10.4097/kjae.2014.67.4.240

Abstract

BACKGROUND
Rapid evaluation and management of intracranial pressure (ICP) can help to early detection of increased ICP and improve postoperative outcomes in neurocritically-ill patients. Sonographic measurement of optic nerve sheath diameter (ONSD) is a non-invasive method of evaluating increased intracranial pressure at the bedside. In the present study, we hypothesized that sonographic ONSD, as a surrogate of ICP change, can be dynamically changed in response to carbon dioxide change using short-term hyperventilation.
METHODS
Fourteen patients were enrolled. During general anesthesia, end-tidal carbon dioxide concentration (ETCO2) was decreased from 40 mmHg to 30 mmHg within 10 minutes. ONSD, which was monitored continuously in the single sonographic plane, was repeatedly measured at 1 and 5 minutes with ETCO2 40 mmHg (time-point 1 and 2) and measured again at 1 and 5 minutes with ETCO2 30 mmHg (time-point 3 and 4).
RESULTS
The mean +/- standard deviation of ONSD sequentially measured at four time-points were 5.0 +/- 0.5, 5.0 +/- 0.4, 3.8 +/- 0.6, and 4.0 +/- 0.4 mm, respectively. ONSD was significantly decreased at time-point 3 and 4, compared with 1 and 2 (P < 0.001).
CONCLUSIONS
The ONSD was rapidly changed in response to ETCO2. This finding may support that ONSD may be beneficial to close ICP monitoring in response to CO2 change.

Keyword

Carbon dioxide; Hyperventilation; Optic nerve sheath diameter; Ultrasonography

MeSH Terms

Anesthesia, General*
Carbon Dioxide
Humans
Hyperventilation*
Intracranial Pressure
Optic Nerve*
Ultrasonography
Carbon Dioxide