Ocular compression pressure during EEG for the study of increased vagal reactivity

Ocular compression (OC) is a maneuver performed during EEG to demonstrate increased vagal reactivity in children with suspected syncope including breath-holding spells. We examined the relationship between the simulated OC pressure exerted by different physicians and the cardiac slowing responses that they had historically obtained as per EEG records. Simulated OC was performed by each physician using a sphygmomanometer. EEGs were reviewed for the rate of positive cardiac slowing per physician. Among three physicians who performed a total of 73 OC, the mean +/- SD of applied pressure were 29.0 +/- 2.4, 60.7 +/- 3.5 and 42.4 +/- 2.5 mmHg, respectively. There was good intra-physician consistency for the OC pressures exerted. The mean pressure exerted was significantly different between physicians (p < 0.001, ANOVA). The positive response rate for cardiac slowing among these physicians was 11/37 (29.7%), 10/21 (47.6%) and 8/15 (53.3%) respectively. The difference in positive OC responses between physicians was not significant (p = 0.127, chi-square). Higher OC pressures did not translate into more positive responses. A pressure of 30 mmHg is as good as 60 mmHg in demonstrating cardiac slowing during OC.