Page 194 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars

Result of the die
Session 1
Session 2
Session 3
Session 4
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Chapter 9
Table 9.1
Rigid collar regime
10011 20101 31001 41010 51100 60110
0, no collar; 1, collar applied.
or not. This was done to blind the observers to audible clues as to the application or absence of the collar. During every session, heart rate, blood pressure, and blood oxygen saturation (SpO2) were monitored noninvasively (Infinity M540; Dräger, Lübeck, Germany).
Images of the ONSD in the left and right eye were taken simultaneously with two identi- cal M-Turbo® ultrasound machines (Fujifilm SonoSite Inc., Bothell, WA, USA). They were equipped with a 7.5 MHz linear-array transducer at ocular setting; mechanical index = 0.2. Axial measurements were carried out in B-mode. The images were frozen at the same time and ONSDs were measured by each sonographer on their machine with the internal calliper at 3 mm behind the retina as suggested before (Figure 9.3).9–13 One sonographer measured all left eyes and the other sonographer measured all right eyes throughout the study.
Statistical analyses
Categorical variables are presented as numbers and percentages. Continuous data are pre- sented with ranges and as mean ± SD when normally distributed or as median values and cor- responding 25th and 75th percentiles when data were skewed. The intra-observer variability was calculated as the mean difference between two measurements for each eye/observer with and without application of a collar and reported as mean ± SD. To evaluate the effect of a collar on ONSD, linear mixed models were fitted. This method of analysis takes into account the correlated nature of repeated measures of the same participant. The models included volunteer as a random factor and collar, eye and collar by eye as fixed within-volunteer ef- fects. IBM SPSS Statistics for Windows, version 22.0 (IBM Corp., Armonk, NY, USA) and R (version 3.2.5, R Foundation for Statistical Computing, Vienna, Austria) were used.