It was suspendend because the protocol and the aims were modified

Critically ill patients under mechanical ventilation (MV) have pain, anxiety, sleep deprivation and agitation. The use of analgesics and sedatives drugs (sedoanalgesia) is a common practice to produce pain relief and comfort during the VM. Despite its usefulness, it has been documented that the excessive use of sedatives is associated with an increased risk of prolonging the stay under MV and in the Intensive Care Unit (ICU). To avoid this, current evidence suggests the use of protocols guided to clinical goals, such as the sedation-agitation scale (SAS), or daily suspension of infusions to avoid excess sedation. These protocols minimize the prescription of deep sedation, which is still necessary for 20-30% of patients.

Monitoring of sedation with electroencephalography in the ICU has been underutilized. In fact, only the use of indices that are generated from algorithms of the electroencephalographic signal processing has been reported. However, it has been shown that the use of these monitoring systems does not benefit the heterogeneous groups of patients in MV. Currently, the clinical monitors used to measure the effect of drugs used in a sedoanalgesia show in the screen the spectrogram of the brain electrical signal and quantify the frequency under which 95% of the electroencephalographic power is located, known as spectral edge frequency 95 (SEF95). This value in a person who is conscious is usually greater than 20 Hz, in a patient undergoing general anesthesia it is between 10 and 15 Hz. In preliminary measurements, in deeply sedated patients in the ICU, SEF95 values are under 5 Hz. This would indicate that patients in the ICU are being overdosed. It is unknown if in cases with an indication of deep sedation, the use of monitoring by spectrogram is superior to the standard management guided at clinical scales, such as SAS.

Therefore, the investigators propose the following hypothesis: In patients with an appropriate indication of deep sedation (SAS 1-2), the sedoanalgesia guided by the spectral edge frequency 95 reduces the consumption of propofol compared to the deep sedoanalgesia guided by the sedation scale agitation in MV patients in the ICU maintaining a clinically adequate level of sedation.

To determine whether deep sedoanalgesia guided by the spectral edge frequency 95 decreases propofol consumption with respect to deep sedoanalgesia guided by the sedation-agitation scale in patients hospitalized in the Intensive Care Unit under mechanical ventilation.

• Group intervention: sedation will be guided by SEF95 and SAS. Patients will be sedated to keep a SAS 1-2 with a SEF95 between 10 to 13 Hz.
• Group control: sedation will be guided by SAS. However, SEF95 will be also recorded but covered.

Inclusion Criteria:

• Older than 18 years
• Indication of deep sedation with propofol and fentanyl for more than 48 h

Exclusion Criteria:

• Brain damage
• Cognitive impairment
• Allergy to propofol or fentanyl
• Limitation of therapeutic effort
• Liver chronic disease Child C
• Prone positioning and use of neuromuscular blocking agents