SCCM Pod-536 CCM: Healing Sleep Patterns Post-ICU
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Hello, and welcome to the Society of Critical Care Medicine's podcast. I'm your host, Kyle Enfield, and today I am speaking with Dr. Adriano Targa, PhD, about the article Sleep and Circadian Health in Critical Survivors, a 12-month follow-up study published in the August 2024 issue of Critical Care Medicine. To access the full article, visit cpmjournal.org.

Dr. Karga is a researcher at the Center for Biomedical Research Network Cyber in Madrid, Spain. Welcome, Dr. Karga, and thanks for taking the time out of your day to meet with me and talk about this article. I'm really excited about our conversation. Before we dig into the work that you've done, do you have any disclosures you'd like to report?

Well, I have no disclosure. Thank you for a nice presentation. So recovery from critical illness is definitely something that has been obtaining a lot of importance in our work. Tell me a little bit about what got you and your research group interested in looking at the sleep patterns of people who have survived critical illness and what led you to start this study?

Actually, this study started with the COVID-19 pandemic. I worked in a group of sleep researchers and also pneumologists. So the idea was to perform a follow-up of these patients more in terms of respiratory function. But we also decided to take advantage of this situation to study the sleep of these patients because the data showed

The literature at the moment was subjective data in terms of sleep health and also only one question, for example, asking whether the sleep, the patient felt like his or her sleep was disturbed. So we wanted to dig deeper on this matter and start a more complete evaluation.

So the idea started with the pandemic, and that was because our project was focused on critical patients due to COVID-19. So we started a project at that moment, and we decided to perform subjective and objective evaluations because that was also not present in the literature at that moment. So the idea started with that. Now, of course, we have more projects ongoing to evaluate this matter on

critical patients due to other causes other than COVID-19. So I wonder if we could also back up just a little bit and ask what got you interested in sleep chronobiology? Why should critical care and health practitioners in general be interested in this subject? What did you get interested in and why is it important to us as a healthcare provider community?

Sleep is a really important factor for the overall quality of life. So at short term, if we don't have a good sleep health, we will have a lot of problems at short term in terms of quality of life, tension and consolidation of memories.

late-time sonolence, for example, and that's one thing. And maybe that's not the most important thing if we're thinking about critical survivors because they have a lot of other problems in the short term. But then, like a complete recovery of these patients, the sleep health, it's very, very important because we can see, like the studies indicate, we do have evidence

of a close relationship between sleep, health and the immune function, for example. So if you want a complete recovery, we have to think about the relationship between sleep and immune function and also the role of sleeping, especially the circadian rhythms on respiratory function. So I think that if we are thinking about critical patient, of course, the benefits of a good sleep health can be seen at short term in terms of quality of life, but maybe

We can see that clearly because of other situations, conditions that the patient is suffering at that moment. But especially in the long term, if you want to have a complete recovery of these patients, we have to think in a really, really good city care and health. In terms of the outcomes associated with a poor sleep health in the long term, the development of a lot of conditions due to a poor sleep health.

So I think it's a matter that it's very important, obviously, if we look at short term, but even more when we look at the long term. So as you guys approach this study, what were the sort of the big things that you found, sort of the key findings and maybe what was some of the findings that surprised you and your research team?

We observed that there's a high prevalence of poor sleep quality. The study that we are commenting on is the third study, because if you are talking about a COVID-19 pandemic, we started with a three-month follow-up, then we performed a six-month assessment, and then a 12-month follow-up. And we can see that, for example, there's a high prevalence of

of poor sleep quality at the three-month follow-up, around 60% of patients reporting poor sleep quality. And then we have like a slight improvement in terms of sleep quality at a 12-month follow-up. And that's interesting because the values

are quite similar of the general population with indirect comparisons obviously but I think an interesting point is that the circadian health doesn't change so we we

We do have a higher fragmentation of the rhythm in a group of patients that remains the same. The fragmentation of the rhythm remains the same along the 12-month follow-up. So we do not see any improvement in 12-month follow-up. There's a lot of other things, obviously, but we can see some markers, predictors of this high fragmentation at the 12-month follow-up, like the days of hospitalization or the invasive mechanical ventilation.

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Maybe for some of us not as in tune with sort of coronal biology and sleep, can you speak briefly about the normal circadian patterns that you would expect to see in say a normal person and then compare that a little bit to the changes you see in these critically ill patients? Well, in a healthy person, we expect to see like a really stable rhythm.

with some kind of routine in terms of activity of sleep time or time of awakening, for example. We expect to see some kind of stability along the days during the week and we also expect to see a higher amplitude of the rhythm. That means that we expect to see higher activity during the active phase and lower activity during the rest phase.

And we also expect to have a good pattern. For example, you expect to see a continuous pattern of activity during the activity phase and a continuous pattern of lower activity during the rest phase.

What we are seeing in critical survivors due to COVID-19 is that this continuous pattern of activity during the active phase and this continued pattern of low activity during the rest phase is not observed. We can see a lot of fragmentation of this rhythm. So we can see a lot of periods of inactivity during the active phase and periods of activity during the rest phase. So this is something that you

with respect of a person that has a lot of naps, for example, or a person that has some kind of lip disturbance that makes him or her remain active during the night.

So we don't know exactly the reasons why a critical patient has a lot of augmentation of the rhythm, but this is what's happening and this is what is unexpected at 12-month follow-up. You would expect it at three-month follow-up, for example, but at 12-month follow-up, that's a lot of time.

So obviously you guys are still doing research, but any thoughts about what might be steps that clinicians can take for their recovering patients to help with this? Are there known strategies or known thoughts right now in your field about what we might be recommending to our patients who are surviving critical illness right now?

Well, with our study, I think it's important to highlight this. We can establish relationships of causality because it's an observational study. But we know some factors that might increase the fragmentation of the rhythm, which are like the constant exposure to artificial light or mistimed exposure to light.

artificial light, interruptions during the ICU stay, the noise of the equipment or the personnel, the interventions which are necessary most of the time, but we can try to adjust that. Also the lack of exposure to sunlight.

There are a lot of factors that could increase the fragmentation of the rhythms. In terms of the ICU state, what we can do is try to avoid these factors whenever it's possible. And also we have ICUs with windows in which the patient can be exposed to some kind of natural light.

We have some places that we can adjust the timing, the exposure to artificial light or noise. So there are some things that we can do, but this is not a behavior or an attitude that we can do as a clinician. For example, it's impossible to do that alone. This is a situation that needs to be adjusted as a group in an organized context. So these are...

the factors that could be avoided or adjusted to try to decrease this fragmentation of the rhythm. Also, even if we can do that in terms of in a tentative to decrease the fragmentation of the rhythm, we can see these factors like the time and the duration of the ICU stay or the time spent at the ICU or the duration of invasive infection.

mechanical ventilation as markers of this increased fragmentation. So if I know, even though I can establish a causal relationship, if I know that a patient that received invasive mechanical ventilation or that spent a lot of days at the ICU will have a high probability to have a fragmentation of the rhythm, I can try to adjust the follow-up of this patient in a tentative to decrease this fragmentation. So these are...

some of the factors. We also observed some kind of correlations between the respiratory function and the fragmentation of the rhythm at the 12-month follow-up. So this also could be a marker of a patient with probability of having high fragmentation of the rhythm. It's interesting to highlight, as I previously mentioned, that we can't infer if there is causality here, but it's important to see these factors

as markers of a possible fragmentation of the rhythm and then provide appropriate follow-up for the patients. You said you guys are doing some additional studies now because obviously this is a population enriched for COVID-19. Do you expect to see the same findings in other critically ill patients or do you think this is unique to that population of patients?

This is exactly what we are doing right now. We have a project that we are recruiting patients of causes other than COVID-19 to see whether this

alterations that we observed with critical COVID-19 patients are also true for critical patients in general, because we hypothesize that the effects that we are observing are due to ICU stay or the invasive mechanical ventilation, but we can't prove that yet. So we are trying to

observe that with other critical patients to see if we can replicate the results or if the prevalence of poor sleep quality or the prevalence of higher fermentation of the return is different compared to COVID-19 patients. We hypothesize that the effects that we have are due to ICU state or the disenvironment of the ICU and not due to the disease itself. Because if we looked at

At the other indicators, the severity of the disease, even though in the article the invasive mechanical ventilation is used as a marker of severity of the disease, if we look at other markers, we don't see any relationship with the fragmentation of the rhythm, for example. So we hypothesize that this is more related to the context of the ICU than to the disease itself.

I think a lot of us are looking forward to seeing that. I think we all shared that hypothesis and we'll be excited to see your results. Before we wrap up, are there any questions I should have asked or things that you wanted to share with the audience? Maybe it would be interesting to talk about some articles, the follow-up article of this one, because now we have a 24-month follow-up article, which is the last one of this study, obviously.

And it's interesting because we thought when we were observing the results of the 12-month follow-up that the sleep quality was almost normal, you know, because you can see a slight improvement close to the prevalence of general population.

But what we are seeing in this final article is that there are patients that require 24 months to recover their sleep health. So this is interesting because now we can see that there are two groups of patients, for example, one group that starts with good sleep quality at three months follow-up

and remains with a good sleep quality during the follow-up. But there is another group which starts with a poor sleep quality, the three-month follow-up, and this poor sleep quality is recovered. Well, it changes and it gets to the point of good sleep quality similar to the other group. In terms of the circadian function, we don't have the results yet, but in terms of sleep, it is interesting. And the most interesting part in terms of sleep

specifically is that it doesn't correlate with anything, with the baseline characteristics or the invasive mechanical ventilation or the ICU state, but with mental health. The curves of improvement or the evolution of the mental health

is really, really similar to the evolution of sleep health for both groups, the ones with a poor sleep quality at three months follow-up and the ones with a good sleep quality at three months follow-up. But these results,

will not be the same for the circadian rhythms, probably. Because what we saw during all the studies during this investigation is that sleep health is mostly associated with mental health in general, and the circadian rhythms are more related to the ICU or invasive mechanical ventilation. So the focus is that in terms of critical care would be

more related to the circadian rhythms than to the sleep quality in this specific population.

That's fascinating. Thank you so much for sharing those early results for your 24-month study, and we'll look forward to seeing the circadian health data as well. This is going to conclude another episode of the Society of Critical Care Medicine's podcast. If you like what you heard, consider rating and reviewing us. For the Society of Critical Care Medicine, I'm your host, Dr. Kyle Enfield. Have a great day.

is an associate professor of medicine in the Division of Pulmonary and Critical Care at the University of Virginia. He received his undergraduate degree from the University of Oklahoma. Join or renew your membership with SCCM, the only multi-professional society dedicated exclusively to the advancement of critical care. Contact a customer service representative at 847-827-6888 or visit

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