Page 196 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars

Range ONSD (mm)
Average ONSD (mm)
Intra-observer variability
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Chapter 9
Results
Twenty-two male and 23 female volunteers were included. Their ages ranged from 18–31 (mean 20.3 ± 1.9) years. None used vasoactive medication of any kind. Systolic blood pres- sure (131.8 ± 8.7 mmHg), diastolic pressure (77.2 ± 5.6 mmHg), pulse (78 ± 10.8 min–1), and peripheral oxygen saturation (98 ± 1%) were within normal limits. In total, 360 ONSD mea- surements were performed in 45 volunteers. Intra-observer variability varied between 0.001 ± 0.05 and 0.005 ± 0.05 (Table 9.2).
Table 9.2 Intra-observer and inter-observer variability
Left eye (observer 1) Collar
No Collar
Right eye (observer 2)
Collar
0.38–0.78 0.40–0.78 0.38–0.69 0.40–0.69 0.40–0.69 0.42–0.66
ONSD, optical nerve sheath diameter.
0.54 ± 0.07 0.57 ± 0.07 0.51 ± 0.06 0.53 ± 0.06 0.54 ± 0.07 0.53 ± 0.06
– 0.03 ± 0.07 0.02 ± 0.06
0.001 ± 0.05 –0.005 ± 0.05
0.003 ± 0.05 0.005 ± 0.05
No Collar
Interobserver variability (observer 1 vs. observer 2)
Collar No Collar
The application of the collar resulted in a significant overall increase in ONSD (5.5 ± 0.7 mm vs. control 5.2 ± 0.6 mm, p < .001) (Figure 9.4). However, a significant effect of eye (left vs. right) and the interaction of eye and collar was observed (Table 9.3). Stratification on eye showed an increase of ONSD of 0.6 mm (p < .001) in the left eye and 0.1 mm (p = .027) in the right eye after application of the collar.