Oversedation and occurrence of negative outcomes
Sedation is widely used in the intensive care unit (ICU) setting to tolerate invasive procedures and ensure comfort to the patient (1,2) Only a limited number of ICU patients have a condition requiring deep sedation (i.e acute brain injuries, severe respiratory failure and cardiogenic shock). Deep sedation, while essential in caring for these specific patient populations, is associated with negative impacts such as longer mechanical ventilation, ICU stay, delirium and higher mortality (2-5). These negative patient outcomes have been linked to the depth of sedation (3,6-8). Studies have found that oversedation in the first 48 hours of sedation is linked to longer time to extubation, higher delirium and higher hospital mortality (6-8).
Minimal sedation
The PADIS guidelines (Clinical practice guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility and Sleep Disruption in Adult Patients in the ICU), which serve as a reference in managing pain, agitation, delirium and sedation in the intensive care unit, recommend minimizing the use of sedation in all patients (9). Most mechanically ventilated ICU patients should receive minimal sedation, allowing for better patient ventilator interaction and reducing pain and anxiety (1,3). Still, providing the necessary amount of sedation to alleviate pain, anxiety and agitation, while avoiding oversedation and related adverse effects, calls for accurate sedation assessment (10).
Evaluating depth of sedation and current limitations
Currently, validated behavioral scales are used in clinical practice to assess sedation depth in ICU patients and guide titration of sedative medication (9). The Richmond Agitation and Sedation Scale (RASS) is the most commonly used scale and is well validated for intensive care patients (11). However, behavioral scales are not suitable for fully unresponsive patients, thus they do not discriminate levels within the deepest ranges of sedation (RASS -5 to -4), which may be required to enable ventilation in patients with severe respiratory and/or circulatory failure. The need to develop more objective ways to monitor deep sedation, such as pupillometry, is of outmost importance in these patient populations, in which over-sedation has the greatest impact on outcomes.