As the name implies, the intensive care unit (ICU) is where a hospital's sickest patients who require accelerated and concentrated care are admitted. Many of these patients, an estimated 33% of all admissions, are admitted for respiratory failure of one etiology or another and subsequently are intubated and placed on mechanical ventilatory control. Part of the standard of care for intubation is to sedate the patient continuously to reduce pain and anxiety; decrease oxygen consumption and the body’s stress response; prevent patient-ventilator desynchrony; reduce adverse neurocognitive impacts such as depression and post-traumatic stress disorder and ventilator-associated events including pneumonia and tracheostomy, and reduce total nursing requirements.
The medications used to initiate and maintain sedation within an intensive care unit setting include benzodiazepines such as diazepam, lorazepam, and midazolam; opioid analgesics such as fentanyl, hydromorphone, morphine, remifentanil, propofol, dexmedetomidine, and ketamine; and antipsychotics such as haloperidol, quetiapine, and ziprasidone. No sedative is found to be superior in efficacy or mortality. However, The Society of Critical Care Medicine guidelines state to avoid benzodiazepines due to evidence of longer duration of intubation. The choice of which sedative is best lies in the practitioner's clinical assessment of individual patient scenarios, weighing the risk/benefit profile of the medicine to each patient.
Regardless of which sedative agent was utilized, total continuous sedation was found to be associated with an extension of the total length of intubation and increased length of the ICU stay and limited the ability to properly assess the mental status of the patient, increased the risk for delirium, and suppressed brainwave function seen on EEG, linking to increased 6-month mortality. It was assessed that daily, short-term cessation of sedation, a “sedation vacation,” led to improved outcomes in patient care.
Sedation vacations were first introduced in 2000 with a study by J.P. Kress et al. that was published in the New England Journal of Medicine and recognized as a medical necessity for standard practice within the ICU to wean patients from mechanical ventilation. The study of spontaneous-awakening trials showed that daily sedation interruptions improved the time to extubation of 64 patients by approximately 2 days which reduced the total admission time to the ICU by 3.5 days. This study was further reinforced by two separate trials, the Awakening and Breathing Controlled Trial in 2008 titled the “wake up and breathe” protocol and the No Sedation in Intensive Care Unit Patients trial in 2010. Both of these supporting trials investigated the impacts of imposing a protocol to evaluate and reduce sedation in a structured format and found that spontaneous-breathing trials along with sedation vacations reduced ventilatory dependent days and ICU admission days when compared to non-structured or no sedation vacation protocols.
Issues of Concern
Sedation vacations can sometimes result in complications, and each one should be addressed accordingly. When sedation is turned off, the patient may not remember that they were intubated and may be unaware of all of the tubes and lines going into their body. Upon awakening, they may be confused and anxious and may pull out the endotracheal tube or other deep lines. This may result in laryngeal injury/laryngeal edema, and if not addressed in a timely fashion, can lead to respiratory failure and may result in death. If the patient is very anxious after the sedation is turned off, this might make the sympathetic drive very high, which can result in tachycardia and high blood pressure. Very high blood pressure, especially in elderly persons, can cause a stroke or myocardial infarction.
Sedation vacations are a balancing act of tightly titrating the sedative dose to provide agitation free, comfortable sedation on the lowest dosage possible. They are patient-specific, as various disease processes and patient tolerances necessitate different doses of medicine. There are two primary scale systems utilized to assess the degree of sedation and agitation present during a sedation vacation withdrawal period to determine success of the vacation versus the need for continued sedation. These are the Sedation-Agitation Scale (SAS) and the Richmond Agitation-Sedation Scale (RASS). Sedation-Agitation Scale places a numerical value on the mental status of a patient, where 1 is an unarousable state, 4 is a calm and cooperative patient, and 7 is a dangerously agitated or combative patient. The Richmond Agitation-Sedation Scale has a similar parameter of mental status assessment with -5 being unarousable, 0 being alert and calm, and +4 being a dangerously agitated or combative patient. These scales provide input when determining how aggressively protocol is implemented. Baseline mental status is also assessed by the ability to follow commands, including eye opening and tracking, hand squeezing, or tongue protrusion.
Several guidelines have been proposed which offer guidance on how to assess and address sedation vacations. One such protocol with proven benefit is the Wake Up and Breathe protocol which combines spontaneous-awakening trials where sedative medicine is withdrawn to awaken the patient with spontaneous-breathing trials where the body’s readiness to extubate from mechanical ventilation is assessed in stepwise fashion where ability to undergo spontaneous awakening trial is assessed for safety specifically monitoring for active seizures, active alcohol withdrawal, agitation, use of paralytic agents, active myocardial ischemia, and elevated intracranial pressure. If any are present, spontaneous awakening trials cannot be attempted and should be reevaluated in 24 hours. If none are present, a sedation vacation should be attempted. Markers of failure include agitation per SAS or RASS scales, pain, respiration rate greater than 35 breaths per minute, oxygen saturation less than 88%, respiratory distress, or an acute cardiac arrhythmia. Any markers of failure should prompt the restarting of sedatives at 50% the previous dosage with reassessment in 24 hours.
If spontaneous awakening is successful, a spontaneous-breathing trial should be performed. Markers that it is safe to do so include no agitation, oxygen saturation greater than 88%, FiO2 less than 50%, PEEP less than 8 cm H2O, no active myocardial ischemia, minimal vasopressor requirements, and good inspiratory efforts. If any are present, restart sedation and reevaluate in 24 hours. Signs of spontaneous-breathing trial failure include respiratory rate greater than 35 or less than 8 breaths per minute, oxygen saturation less than 88%, signs of respiratory distress, mental status changes, or acute cardiac arrhythmia. If none of these are present, it is appropriate to consider extubation of the patient. If the patient has been intubated for more than 48 hours and has no cuff leak, then a dose of steroid can be given 4 to 5 hours before extubation and another dose can be given 4 to 5 hours after extubation. This has been shown to decrease the rate of reintubation and laryngeal edema.
The reason for sedation vacation or breathing trial failing should be identified and addressed accordingly. If the patient is getting agitated and is delirious, antipsychotics can be tried; if anxious, anxiolytics can be tried; or if in pain, low dose fentanyl drip/morphine drip or patch can be tried. Patient delirium and agitation can be very well controlled on dexmedetomidine, and as the medication does not suppress the respiratory center, the patient can be extubated while on continuous infusion of dexmedetomidine. Attention should be paid to home medications, and if clinically permitted, a patient who is on any anxiolytics, antipsychotics, or on any chronic pain medications should continue them while sedated or restart them in a timely fashion to prevent withdrawal.