Electrolyte imbalance, liver failure, renal failure, anoxic-ischemic brain injury, drugs, and sepsis may all contribute to encephalopathy. None of our patients had neurologic signs that may be associated with encephalopathy, such as tremor, myoclonus, or asterixis. Four patients had an elevation, albeit slight, in serum creatinine, and three of them were in the IS group and were totally alert. Only two patients had an elevation (insignificant) in serum bilirubin. No patient had oxygen saturations < 90% or systolic BP < 90 mm Hg, which could be associated with anoxic or ischemic encephalopathy. Although the groups did not differ statistically between APACHE II scores, patients in the CS and CS/NMBA groups had higher a LIS, presence of ARDS, use of vasopressor agents, and higher mortality, indicating a sicker group of patients compared to the IS group. other
Severity of illness may account for the change in sleep pattern but was not significant due to the small sample size. A trend was noted in increasing TST and LIS and APACHE II scores, potentially indicating greater requirements for sleep with increasing severity of illness.
Drug effect from benzodiazepines, although statistically insignificant, may have had a clinical effect. IV injection of a benzodiazepine initially causes an increase in (P activity followed by a dose-dependent progressive increase in delta frequency and reduction in EEG amplitude consistent with decreased cerebral metabolism.’ In patients who are critically ill, dose-dependent relationships are highly variable based on renal and hepatic metabolism as well as volume of distribution. When overdosage occurs, various EEG patterns may develop such as a-delta, burst suppression, diffuse slowing, and progression to electrocerebral silence. Light levels of sedation are induced at 0.1 to 0.2 mg/kg of midazolam in healthy subjects (lorazepam dose equivalent is approximately 50%). Either repeat bolus doses or continuous IV infusion at approximately 50% of the dose can maintain sedation. It is unlikely that the increased mDelta activity seen in the CS group was related to other drugs, as only one patient received additional sedation with haloperidol.