Analgesics and sedatives are administered to most patients who are being mechanically ventilated in an intensive care unit (ICU), not only to combat anxiety, agitation, and pain but also to achieve optimal benefits of the ventilatory support. Historically, sedation has been administered via continuous infusion until it is determined that the patient can effectively breathe on his or her own and be extubated. However, continuous sedation is associated with prolonged length of mechanical ventilation, ICU stay, and hospital stay. In addition, certain sedative agents used in this setting place patients at greater risk for ICU delirium, a form of acute brain dysfunction and a life-threatening global disturbance of cognitive function.[1,2] Conversely, protocolized sedation and daily interruption of sedation have been proposed as strategies for improving outcomes in mechanically ventilated patients in the ICU. Susan L. Smith, MN, PhD, Editorial Director for Medscape Critical Care, interviewed Timothy D. Girard, MD, MSCI, about the Awakening and Breathing Controlled (ABC) Trial, a randomized controlled trial of the efficacy and safety of a paired sedation and ventilation weaning protocol for mechanically ventilated patients in intensive care.
Medscape: To set the stage, would you define spontaneous awakening and spontaneous breathing trials, in the context of the study?
Dr. Girard: I will start with the spontaneous breathing trial because it is a well-known test that we use to assess mechanically ventilated patients in the ICU that in many senses has become a standard of care for patients with acute respiratory failure on mechanical ventilation. I would define the spontaneous breathing trial as a period of time during which a patient with acute respiratory failure who is mechanically ventilated is allowed to breathe spontaneously without the assistance of the ventilator.
Medscape: The ventilator is disconnected for a short period of time?
Dr. Girard: It can be done in several different ways, and the classic way is to disconnect the patient from the ventilator with the endotracheal tube left in place and attached to a T-piece, sometimes called a T-tube. Another way is to leave the patient connected to the ventilator, but change the settings and the mode of the ventilator so as to provide no support or a very low level of support. For instance, giving a patient on pressure support ventilation ≤ 7 cm H2O inspiratory pressure is considered a spontaneous breathing trial.
Medscape: And what about a spontaneous awakening trial?
I would say that a spontaneous awakening trial is a concept that parallels the spontaneous breathing trial, but the therapy of interest is sedation instead of mechanical ventilation. We purposely called it a “spontaneous awakening trial” because “spontaneous breathing trial” is a widely recognized concept among intensivists, and we wanted to use a similar term for easy recognition.
The spontaneous awakening trial is a period of time during which a patient’s sedative medications are discontinued. They are allowed to wake up and spontaneously achieve a normal level of alertness. During this time we monitor patients to see if they are comfortable when they wake up. If they become responsive to voice without signs of intolerance, pain, or respiratory failure, they “passed” the trial. If upon wakening, they demonstrate signs of agitation, anxiety, pain, or respiratory compromise, they “failed” the trial, and sedation is restarted.
Medscape: Why was it important to conduct the ABC trial; was there a particular knowledge gap that you were trying to address?
Dr. Girard: The knowledge gap that we were trying to address was whether this systematic, protocolized approach to management of sedation and the ventilator is superior to a more individualized approach that is not systematically applied across the spectrum of ICU patients. Dr. Kress and colleagues conducted a trial nearly a decade ago that showed that turning off the sedation once a day resulted in a shorter time on the ventilator and a shorter time in the ICU compared with usual care. But that trial had limitations, and it wasn’t widely accepted or widely implemented in clinical practice. Recent surveys have found that < 50% of ICUs are using daily interruption of sedation. One of the limitations was that it was a single-center trial in a university hospital, and there was a lot of uncertainty about whether it could be safely implemented in a community hospital setting or in ICUs that were different from the one included in the trial. In addition, there was no standardized approach to the management of the ventilator in that trial, so there were questions about whether the benefits would be achieved in patients managed with a standardized weaning protocol. Finally, there were also questions about the psychological effects of turning off sedation while ICU patients are on the ventilator, potentially exposing them to painful or noxious stimuli, which that trial did not measure prospectively. These are some of the limitations and questions that we wanted to address in the ABC trial. We also wanted to take the protocol to another level by streamlining the management of sedation and the management of the ventilator into one protocol that could be implemented easily in an organized fashion.
Medscape: What are the most important findings from the ABC trial?
Dr. Girard: There are three main findings. First, patients in the intervention group, who were managed with the wake up and breathe protocol, spent an average of 3 more days off of the ventilator during the study than patients who were managed in the control group with sedation according to usual care. Second, patients in the intervention group were discharged from the ICU and the hospital about 4 days earlier than patients in the control group. And finally, patients in the intervention group experienced a 14% absolute reduction in the risk for death in the year following enrollment, compared with patients in the control group.
Medscape: Are the results of this trial applicable in ICUs that already use sedation protocols to achieve light sedation?
Dr. Girard: We believe the results are applicable in ICUs that use light sedation because the protocol affects not only the level of sedation that is achieved but the manner in which it is achieved. The ICUs that participated in this trial all used a targeted strategy of sedation based on validated sedation scales as part of usual care. Nurses and physicians were attempting to achieve light sedation by adjusting the level of sedation according to their perceptions of the patients’ clinical need. We found that the wake up and breathe protocol was an improvement over that approach to sedation. I also think it is beneficial because our best efforts at achieving light sedation are not always realized; a number of observational studies show that even when a sedation protocol is used, patients are often oversedated. We think that our protocol will help reduce oversedation in the ICU and will be of benefit even in ICUs that currently use sedation protocols.
Medscape: Are there patients who wouldn’t be candidates for this protocol?
Dr. Girard: I should point out that the protocol hasn’t been tested in surgical ICU populations; we only enrolled medical ICU patients. We don’t know that it wouldn’t benefit surgical ICU patients, but we also can’t say that it would. The main reason that we did not enroll surgical patients was the concern that they would need higher doses of analgesics and that interrupting or stopping those analgesics that have sedating properties could be problematic in patients who are recovering from recent surgery. So that is one note of caution. Another is that the protocol was designed to allow an individualized approach, according to the patient’s current needs. For example, there is a safety screen that must be met on a daily basis before the patient’s sedative medications are interrupted, and only certain patients are deemed safe to have their drugs turned off and undergo a spontaneous awakening trial. One example is the patient who is going through alcohol withdrawal; this patient wouldn’t pass that safety screen and therefore wouldn’t be considered safe for a spontaneous awakening trial.
I wouldn’t say that you can’t use the wake up and breathe approach for a patient with alcohol withdrawal, but you have to consider, on a daily basis, whether the patient has recovered from alcohol withdrawal or is still in active withdrawal. If the patient is in active withdrawal, then we wouldn’t implement the protocol on that particular day, but would reassess the patient on a daily basis. When the patient is no longer going through active withdrawal, the protocol would be initiated.
Medscape: Many studies have confirmed what is already obvious to anyone who has worked or has been cared for in an ICU, namely that the ICU experience can be very traumatic. What should ICU doctors and nurses know about the long-term psychological effects of the wake up and breathe protocol?
Dr. Girard: To assess the long-term psychological effects of the wake up and breathe protocol, we followed for 1 year after enrollment all of the 187 patients who were enrolled at the largest center that participated in the trial, which was Saint Thomas Hospital in Nashville, Tennessee. The patients who survived to ICU discharge were evaluated for psychological and cognitive outcomes at hospital discharge, and again at 3 months and 12 months after enrollment. Because these data have not yet been published, the results should not be described until they have undergone peer review. But, Medscape readers should be aware that we do have data regarding the long-term psychological safety of the wake up and breathe protocol, and the results should be published sometime in the next 6 months.
Medscape: Is there anything else you would like to say?
Dr. Girard: Yes. One of the most important aspects of this protocol is that it involves removing or withholding therapies as opposed to adding therapies; therefore, the expense of the protocol is low, outside of the time spent implementing it, which should not be significantly greater than what is normally done in the ICU. These treatments — managing sedation and managing the ventilator — are already done on a daily basis in the ICU. The protocol streamlines care that so that it is done in an organized manner according to particular criteria. So, we don’t think that it significantly increases the cost of patient care. In fact, in addition to the benefits to the patient’s health, it may actually save a large amount of money because patients are leaving the ICU and the hospital an average of 4 days earlier.
Interviewee: Timothy D. Girard, MD, MSCIB, Instructor in Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee; Attending Physician, Vanderbilt University Medical Center, Nashville, Tennessee
Disclosure for Interviewee: Timothy D. Girard, MD, MSCI, has disclosed no relevant financial relationships