“…The ineffectiveness of remifentanil at these doses is in contrast with the potent effect of this opioid described in previous studies [3,4,5,6]. It has been suggested that there may be a dose effect for the occurrence of chest wall rigidity associated with remifentanil [2,7]. To better understand the link between high doses of remifentanil and the observed insufficient sedation, we believe it would have been relevant to provide the interval duration between each injection.…”