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Do we need a basis bolus concept for sedoanalgesia of mechanically ventilated patients in ICU?


Tolerance for mechanical ventilation is generally achieved by continuous application of analgesics and sedatives. Their effect is usually controlled by physical examination. The dosage in daily routine occasionally is not adapted to the patients needs in the circardian course. Evidence exists that classical neurological and hemodynamic parameters do not always reflect the level of sedoanalgesia. Neuromonitoring with heart-rate-variability (HRV) is a new opportunity to evaluate the patients neurological status. HRV is a window for usually invisible central autonomic regulation. This phenomenon is caused by oscillation in the interval between consecutive heart beats. It represents a quantitative marker of autonomic activity. Currently monitoring of autonomic nervous system is no routine tool for mechanically ventilated patients. Our study presents first results of continous neuromonitoring of autonomic nervous system with heart-rate-variability in the setting of an intensive care unit.


We studied 10 mechanically ventilated patients (5 male, 5 female without any cardiovascular diseases in case history who received analgesics (Fentanyl®) and sedatives (Dormicum®) continuously. Heart-rate-variability was recorded with flash-memory recorder, the analysis of HRV was performed by a special software (both elamedical, Munich). We investigated over a period of 24 h in each case.


The investigations show considerable variations regarding to the level of HRV parameters in the circadian course. During night time frequency domain parameters of HRV go down (total power: 85.88 ± 19.10 ms2), while they increase during daytime (170.66 ± 57.29 ms2) with a considerable variation. Nursing and medical manipulations as well as the doctor's round at bedside in the morning time lead to a conspicuous increase of total power [mean ± SEM]:


Continuous monitoring of the autonomic nervous system with heart-rate-variability is a new approach to demonstrate the status of the patients sedoanalgesics. It shows considerable variations of autonomic activity in the circadian course. Especially during manipulations at the patients bedside a dysbalance of central autonomic activity seems to appear. A basis-bolus-administration of sedoanalgesia seems to be a useful concept to compensate the undesirable and obvious dysbalance of central autonomic activity under stress situations like doctor's round at the bedside of mechanically ventilated patients with sedoanalgesics.

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Lewejohann, JC., Düpree, HJ., Gleiβ, J. et al. Do we need a basis bolus concept for sedoanalgesia of mechanically ventilated patients in ICU?. Crit Care 3 (Suppl 1), P128 (2000).

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