By Kathryn Radigan, MD
Attending Physician, Division of Pulmonary and Critical Care, Stroger Hospital of Cook County, Chicago; Assistant Professor of Medicine, Rush University Medical Center
Dr. Radigan reports no financial relationships relevant to this field of study.
SYNOPSIS: Recall of the ICU stay and the type of sedation strategy did not influence the types of memories reported by critically ill patients.
SOURCE: Burry L, et al. Recall of ICU stay in patients managed with a sedation protocol or a sedation protocol with daily interruption. Crit Care Med 2015 Oct;43:2180-90.
Survivors of critical illness may suffer from long-term physical, cognitive, and psychological morbidity. Interest in the cognitive and psychological outcomes of critically ill patients has grown tremendously within the last decade. Since the relationship between depth of sedation and degree of patient recall and perception of stressful experiences remains unclear, Burry et al decided to explore this relationship further within the daily sedation interruption in mechanically ventilated critically ill patients cared for with a sedation protocol (SLEAP) trial.
This North American trial was a prospective cohort study that examined 480 mechanically ventilated medical and surgical ICU patients randomized to either protocolized sedation (PS) or PS plus daily sedation interruption (PS + DI) to maintain light sedation. Opioid and benzodiazepine infusions were titrated according to a protocol that emphasized pain management (goal Richmond Agitation-Sedation Scale score of -3 to 0 or Sedation-Agitation Scale score of 3-4). After patients in the PS + DI group awoke, infusions were resumed at 50% of the last recorded dose and retitrated per protocol. By using the ICU Memory Tool on days 3, 28, and 90 post-ICU stay, the investigators were able to evaluate the factual, emotional, and delusional memories of ICU stay for patients, compare characteristics of critically ill patients with and without ICU recall and delusional memories, and determine factors associated with delusional memories 28 days after ICU discharge. Patients were categorized as having no recall of the ICU if they answered no to the question, “Do you remember being in the ICU?” Since results revealed no differences in recall status or types of memories between the PS and the PS + DI group, the manuscript focused on findings for all patients rather than by specific SLEAP study groups.
On days 3, 28, and 90 post-ICU discharge, 28%, 26%, and 36% of patients, respectively, reported absolutely no recall (overall perception, self-reported) of their admission to the ICU (P = 0.75). Mean daily doses of opioids and benzodiazepines were lower in patients without ICU recall than in patients with ICU recall (P < 0.0001). Even though approximately one-third of patients reported no ICU recall on day 3, 97% and 90% recalled one factual and one emotional memory from the ICU. Patients’ emotional memories dissipated with time after ICU discharge. Delusional memories 28 days after discharge were common but unrelated to delirium (P = 0.84), recall status (P = 0.15), and total dose of benzodiazepine (P = 0.78) or opioid (P = 0.21). Delusional memories were also less likely with longer duration of mechanical ventilation (odds ratio, 0.955; 95% confidence interval, 0.91-1.00; P = 0.04). The type of sedation strategy did not affect the recall of ICU stay and types of memories in critically ill patients. Even with sedation strategies that promoted wakefulness, lack of ICU recall and delusional memories were common after ICU discharge.
COMMENTARY
When I asked my 22-year-old H1N1 influenza survivor about the worst part of being in the ICU, she replied, “I remember repeatedly waking up and not knowing what happened to me.” This anxious and distressed patient was in contrast to a 53-year-old patient who suffered a brain aneurysm resulting in a month-long ICU stay and only remembered the tiles on the ICU floor. Why did the 22-year-old patient have vivid memories of her ICU stay while other patients have no memory? Did the vivid memories of my 22-year-old patient have to do with her age, sedation strategy, type of critical illness, or coincidence?
Using the ICU Memory Tool on days 3, 28, and 90 to describe factual, emotional, and delusional memories of patients enrolled in the SLEAP trial,1 Burry et al hoped to achieve some clarity on the subject. Unfortunately, the investigators concluded that the type of sedation protocol, with or without daily interruption, did not affect recall of the ICU stay or types of memories. Although there were no differences in demographics or clinical results between the two groups, it should be noted that the PS + DI group had higher doses of benzodiazepines and opioids compared to the PS group. Since the PS + DI group received greater opioid and benzodiazepine doses and more bolus doses, it is not clear that each individual group was representative of the population the researchers anticipated. Therefore, the results of this study should be interpreted with caution.
Despite almost one-third of patients being unable to recall the ICU stay 3 days post-ICU discharge; almost all patients reported one factual memory, 90% recalled at least one emotional memory, such as confusion, anxiety, or pain; and 72% reported one delusional memory. Surprisingly, patients who had memories of being in the ICU and those without memories were similar, except those who failed to have ICU memories received lower mean daily doses of benzodiazepines and opioids. Although there is no data to support the idea, investigators hypothesized that those patients without recall had more severe encephalopathy and thus required lower doses of sedative during critical illness.
Even though we learned that 70% of patients experienced delusional memories 28 days after ICU discharge, it is unfortunate that investigators were not able to reveal a significant number of modifiable differences between those who reported delusional memories and those who did not. For instance, the odds of developing delusional memories were slightly higher for those < 60 years of age and lower for patients who required more mechanical ventilation. Otherwise, there was no relationship between delusional memories and drug exposure (including total and mean daily doses), Sedation-Agitation Scale scores, or delirium. These results may be due to the fact that both arms in the trial targeted light sedation, an important goal of care that must be emphasized when treating ICU patients. Furthermore, the study did not specifically examine whether other medications, such as steroids or vasopressors, had an effect on recall/memory.
Although this study fails to identify modifiable risk factors with the potential to improve patient outcomes, it emphasizes the prevalence of patients who suffer psychiatric sequelae of being in the ICU. In light of this knowledge, it is our responsibility to inform our patients and their families know about these possible complications of being in the ICU. We may be the only providers who have knowledge of these potential complications and can help set expectations for post-ICU life. This knowledge may empower patients and families who might otherwise feel defeated.
REFERENCE
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Mehta S, et al. Daily sedation interruption in mechanically ventilated critically ill patients cared for with a sedation protocol: A randomized controlled trial. JAMA 2012;308:1985-1992.
