Table 1.
Neurophysiological data
| Evoked potentials data | Healthy control subjects (n = 20) | Deeply sedated critically ill patients (n = 86) | ||
|---|---|---|---|---|
| Mean latency ± SD (in ms) | Mean latency + 2.5 SD (in ms) | Mean latency ± SD (in ms) | Delayed latency n (%) | |
| SSEP components | ||||
| N9 PL | 9.8 ± 0.6 | 11.4 | 11.0 ± 1.6 | 33 (38) |
| N13 PL | 13.2 ± 0.8 | 15.2 | 14.9 ± 2.1 | 36 (42) |
| P14 PL | 14.6 ± 0.9 | 16.8 | 16.2 ± 2.0 | 32 (37) |
| N20 PLa | 18.8 ± 1.0 | 21.4 | 21.6 ± 2.6 | 41 (48) |
| N9-N13 IPL | 3.4 ± 0.4 | 4.4 | 3.9 ± 0.9 | 14 (16) |
| P14-N20 IPLa
(ICCT) |
4.1 ± 0.5 | 5.3 | 5.3 ± 1.5 | 39 (45) |
| BAEP components | ||||
| Wave I PL | 1.5 ± 0.2 | 2.0 | 1.69 (0.31) | 13 (15) |
| Wave III PL | 3.6 ± 0.2 | 4.1 | 3.96 (0.35) | 34 (40) |
| Wave V PL | 5.6 ± 0.3 | 6.3 | 6.16 (0.61) | 34 (40) |
| I–III IPL | 2.1 ± 0.2 | 2.6 | 2.28 (0.29) | 17 (20) |
| III–V IPL (IPCT) | 2.0 ± 0.2 | 2.5 | 2.20 (0.45) | 15 (17) |
| I–V IPL | 4.1 ± 0.3 | 4.8 | 4.51 (0.59) | 17 (20) |
PL peak latency, IPL inter-peak latency, ICCT intracranial conduction time, IPCT intra- pontine conduction time. PL and IPL of SSEP or BAEP’s components were scored as “delayed” when they were greater than the “mean + 2.5 SD” of the ones of a healthy control group
aN20 was abolished in three patients. N20 PL and P14-N20 IPL were consequently considered as delayed for these 3 patients with abolished N20. Median nerve somatosensory evoked potentials (SSEP) and brainstem auditory evoked potentials (BAEP) components latencies (PL) and inter-peak latencies (IPL) obtained from a group of 20 healthy control subjects (11 women, 9 men, mean age 51 ± 17 years) in our laboratory; and from 86 deeply sedated critically ill patients. Each variable is represented by the mean values of left and right hand sides