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In an interview with biologist María Lourdes Galicia Polo, Mexican specialist in sleep studies, she addresses the importance of PSG/HST home exams

December 10, 2018


As a training Biologist, she studied to become a technician in polysomnography and sleep medicine at The School of Sleep Medicine in Palo Alto, California. She obtained her certification as a TRPSG of the Mexican Academy of Research and Sleep Medicine, in addition to completing the diploma in Respiratory Disorders during sleep, INER.

Neurovirtual News: Could you introduce yourself and tell a little about your professional and academic career?

Maria Lourdes Galicia: I’m a biologist by profession. I conduct sleep studies in basic research on animals at the National Institute of Neurology, and I concentrated myself in the clinical sleep medicine area. Given that biology is a very broad area, which includes medicine and biological rhythms, and that I was more interested in working in the clinical field, also in research, I started doing social work in the Sleep Disorders Clinic of the National Institute of Neurology of Mexico.

NN: You began your work with cats and rats at the National Institute of Neurology. What kind of studies included animals? Were there studies related to sleep at that time or were they yet to be performed?

MLG: Yes, we did research. At that time, certain substances were being studied, certain neurotransmitters that were related to REM sleep, that is, the phase of rapid eye movement sleep. When studying certain waves generated in cats, I started these works with Dr. Anabel Jiménez, who at the time was dedicated to perform this type of study, but mainly in the MOR sleep study in cats, also to see if certain brain structures were damaged and what would happen to these animals and thereby extrapolate the basic research for clinical research.

NN: Is the sleep structure of cats similar to humans?

MLG: They have MOR and Non-MOR sleep, but their sleep is not structured into different stages like ours. The MOR would be equivalent to REM sleep. There are muscle atonia, rapid eye movement and mixed frequencies, as in all mammals. The non-REM sleep can be divided into light or deep, but does not have the grafoelementos that we can see in humans, we cannot distinguish it. What was done in the lab was what Dr. Jiménez was doing together with Dr. René Drucker in the UNAM, this is, evaluate certain brain structures, and investigate what were the areas in charge of different stages of sleep, and see what happened with the animal sleep. Polysomnography equipment was made with paper and ink. We had to stay on watch for the sleep studies. Some people took the day shift and I was always offered the evening shift, my colleagues did not like to go at night.

We had to be aware that cats wouldn’t remove the connector, because what we were doing was placing depth electrodes in the head. We recorded cats and would inject certain substances at times, to see what happened to it, if the amount of REM sleep would decreased or increased depending on the work that it followed at the time.

NN: What year are we talking about when this happened?

MLG: In the year 1988, more or less. I collaborated with Dr. Anabel Jiménez, which in turn, worked with Dr. Drucker.  Dr. Drucker was a very important scientist in the field of sleep. He was a pioneer in basic sleep research, contributed with many things internationally, and chose to do the biology thesis there. I wanted to continue with Dr. Jimenez, but I soon got involved in the clinical area and left the cats and the mice aside. Another line that followed was to inject sleep inducing substances into rats. What we did was put them in a dark place, because rats are nocturnal, we applied the injections and watched how long it took for them to fall asleep or if the substances we injected allowed them to sleep.

NN: How is the work that you develop with Mexico’s institutions working in the field of sleep?

MLG: I was lucky to have been invited to work in different institutions. As I said, I started to work in neurology and then went to the National Institute of Psychiatry. I worked at the National Autonomous University of Mexico, at the invitation of Dr. Drucker, after he knew my work in collaborations that we did. He invited me to work in the UNAM, in medical school, and at that time I worked at the Institute of Psychiatry with Dr. Rafael Salin.  Also at that time, Dr. Pérez Padilla, who is the founder of this clinic and the person who did all that was needed to create the sleep lab at the National Institute of Respiratory Diseases, also asked me. I had the great fortune, in that people who were pioneers of the sleep medicine in Mexico, invited me to come and work here in the INER. In around 1996, they both invited me to work, and I told Dr. Pérez Padilla that yes, I will come to work here.  I was more focused on neurological and psychiatric issues regarding sleep, than in the respiratory ones. But I came to work here, and at that moment, I decided to take another shift at the Faculty of Medicine with Dr. Drucker.  Dr. Drucker was also the founder of the Sleep Clinic at UNAM, which was one of the first clinics to have four rooms. It was one of the biggest clinics. This clinic began with only one room, then two rooms, and now we have five rooms. But I think my love for sleep made people invite me to work on these projects. This gave me a broad view of sleep disorders, because I was able to study them in the fields of neurology, psychiatry, respiratory and cardiology. My vision was broadened, and that is why both institutions allowed me to work with them. They took into account different lines of research and different lines of medicine. This allowed me to work with different doctors, which gave me a very comprehensive view of what is related to sleep studies.

NN: In these institutions, in addition to the clinical part, observing patients to help people suffering from sleep disorders, do you also conduct research? And what kind of research do you lead?

MLG: Yes, I collaborated on researches. What we have done is validate a series of equipment for the study of sleep, substantiating different equipment brands. We were also in charge of making these confirmations, especially of type 3 equipment. We made great advances because we are a work team here, with Type one equipment in the laboratory and with different age groups, and specialists in respiratory disorders, which gave much weight to this place. I also participated in other investigations with the UNAM in neurodegenerative diseases such as patients with spinocerebellar ataxia type 2, in which we recorded a large number of patients whom we observed sleep disorders in. We saw problems with ambulation, insomnia, and many movements during sleep. We also did a study in a Cuban and Mexican population, for which we reviewed a series of studies with Dr. Luis Velásquez, who is one of the most dedicated people in this line of research in ataxia, and we reviewed studies of patients that started with this disease,  who are in the middle of the disease and  who are at the end of the disease, and we have seen what the changes were and which areas were most affected in these patients, for example. These patients have many movement disorders, of course. During the day they cannot walk, they tremble a lot. But at night they have more movement than during the day. They have a very fragmented sleep. We analyzed the microstructure of sleep, reviewed how the sleep spindles were found, the K complexes, and we could see that there is a decrease in the number of sleep spindles. We know that sleep spindles are related to the IQ level in certain people, with that we can see the correlation of how memory deteriorates in these people. Another of the findings that we made with this type of patient is that their REM sleep is affected, and have other neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease. In them we observe that there is a behavioral disorder of the REM sleep. In RBD, we observed that these patients also share these types of problems.

NN: Let’s talk about how a change in the stage of REM sleep leads to an increase in fragmentation. What distinguishes these patients, from who has these types of diseases and who does not have them?

MLG: These patients have a decrease in the amount of REM sleep, and as is well known, in REM sleep we have muscle atony, muscle activity is reduced to its minimum function. There is no motor activity during REM sleep because it is during this phase of sleep that the entire motor system is completely depressed to avoid  dreams being actuated, so what happens in these patients very often is that this sleep is fragmented. Why is it fragmented? Because unlike what happens to them during the day, with limited mobility, they cannot control the movements, and what happens during sleep in these patients is they have a lot of motor activity, moving much more than patients without this condition. What happens to us during this REM sleep? Most of our muscles are completely depressed, we have no motor activity. In fact, if we sleep on our feet, we completely lose muscle tone. As opposed to this type of patient, they have a lot of movement and tend to have excessive motor activity. They begin to act out their dreams, they seem to have locomotion, moving upper and lower limbs, their muscles are working. They even at times make movements as if they were walking. This type of change is observed mainly in this type of patient and also patients with Parkinson’s disease and other neurodegenerative diseases.

NN: And this happens with all kinds of neurodegenerative diseases, Alzheimer’s, Parkinson’s? Is there a relationship between all of them?

MLG: Between Parkinson’s disease and ataxia, there is a very close relationship between one type of patient and another.  Alzheimer’s patients are less prevalent.

Another line of research that has been followed here mainly, is to analyze the effects observed with respiratory disorders, and cognitive changes that occur in different age groups. To also analyze whether there are differences in the prevalence of sleep disorders between women and men , adherence to CPAP treatment in patients with obstructive sleep apnea, and whether there are differences on which adherence to treatment depends, on the socioeconomic level,  on academic level, gender, or age. This is another of the lines of research that we have here at INER. In fact, there is a CPAP clinic where patients are monitored individually. Patients who are already on treatment are called periodically. Until a year ago we had a social worker here who was in charge of calling them regularly, asking how they were, why they had not gone to the consultation, how long they were using the equipment, how many hours, if they had changed their masks, if they had not done so. This allowed patients to maintain CPAP treatment by up to 90%. Another line of monitoring we have here is carbon dioxide levels and in a city of large populations like Mexico City, with an altitude of 2,240 meters above sea level, we have a different altitude from that of Colombia. However, we observe here that CO² levels in this population are much higher than those reported in other countries of the world, and that is why cut points regarding carbon dioxide levels are published both in the academy manuals as in the manuals of other societies. In European society they are different. It is said that levels higher than 50 mm of mercury are those that should be considered to diagnose a subject with nocturnal hypoventilation. However, what we are studying here is that when considering an individual to have hypoventilation, carbon dioxide levels should be above 45 mm of mercury, when the normal cut point would be 35, unlike other populations, even in Colombia.

At UNAM we also work with children. We have developed research lines with newborns. We studied a large number of children with respiratory problems, children born premature, for example, and found an important relationship that has also been reported in other countries. We found children with central apnea problems, children of very young mothers, mothers almost in adolescence, and mothers over 45 years of age, are the ones with children having major respiratory problems, mainly central apnea. We observed that in these children there is a greater occurrence of central apnea, unlike other countries in the world. In many children, apnea disappears, in others it does not. But we do not follow what happens to the neurocognitive development of these children in the long-term, we do not really know what is happening, whether it affects them or not. We think it is probably a physiological event, which is part of the development or neurodevelopment of these children and will not affect them, but it really needs to be studied a lot. Something that we have observed, for example, in this type of child, is that they show a lot of intermittent hypoxemia. What is intermittent hypoxemia? The percentage of oxygen goes up and down during sleep, with a very high hourly rate of sleep. However, in the short term, what happens has not been observed. For example, children with obstructive sleep apnea that we have here, we know that they have intermittent hypoxemia, significant cardiopulmonary damage, and can produce pulmonary hypertension over a very short period of time, but it has been seen that children who are not treated have pulmonary hypertension. In newborns, however, this does not happen in the short term. Yes, they have intermittent hypoxemia, but there is no heart condition in these children, whether in the short or long term, they are removed, but we still do not know much what happens to the neurocognitive development of these children. Now, what are the limitations we have with this type of population? It is difficult to record children and babies through the  night, for example.  What happens if we want to keep a record longer, for more nights?  Parents will not want to move to the sleep lab. So what we did was test a type 3 equipment to do sleep study at home. First, we did the sleep study in the laboratory to validate type 3 equipment. However, it is an equipment that has many limitations on the number of channels, regarding the loss of signals, so it was not possible to do the research studies at home.  It was difficult for the parents to prevent the babies from moving, and we had to make the recordings on different nights.

NN: Do you think home testing can make patients who do not have access to a polysomnography exam today be able to get a quality diagnosis?

MLG: Of course. Currently sleep medicine is simplifying, aiming to reduce waiting lists in public health institutions, especially here in Mexico. We have waiting lists of up to one year, with daily studies from Monday to Sunday and with full schedules. What we have established in this institution in recent times is to identify those individuals who have respiratory disorders, obstructive sleep apnea without comorbidities, and we offer them home studies. All effort is directed to this population, to those individuals who have obstructive sleep apnea and without comorbidities, especially adults. Not so much for the pediatric population. I feel that, until now, what is recommended for them is to perform sleep studies, type 1 polysomnograms, which are done in the laboratory. However, what we observe and study is that we can accelerate the study of this population, performing home studies, “simplified studies”, with good results and simplifying time, reducing the time for people to receive treatment for their problems in the short term. Another thing that is also being done is, for example, having patients in the clinical population with respiratory diseases, and with neurodegenerative diseases.

For example, Dr. Martha Torres, head of the clinic here at INER, has a large population of patients with neurodegenerative diseases, mainly Duchenne. These patients are born walking, apparently normal. However, in development, children begin to lose ambulation, they begin to have mobility problems, lose the ability to move limbs, and begin to have a problem with muscle weakness, especially at the level of the rib cage, as well as have respiratory problems, not obstructive respiratory problems, but rather restrictive. What happens to this type of patient? For many of their family members, it is very difficult to transport them to the laboratory. What Dr. Martha Torres did was study these patients in the long term, accompanying a large population of these patients. These patients came with complicated illnesses, worsened with pneumonia, and they arrived at the emergency room, because they were only attended by the area of Pulmonology until presenting complications. They arrive at the emergency room when they are already very committed and it was then that they received attention. However, we the working group, together with Dr. Sonia Meza, opened this consultation for this type of population, and what she began to observe was that these patients have problems with carbon dioxide retention during sleep, especially during REM sleep, because they begin to have problems of nocturnal hypoventilation, only at night. Therefore, when these patients went to the neurological consultation, they presented no problem. What we observed was that during REM sleep they began to have apnea and to retain carbon dioxide. So what the working group proposed, was to start doing a study of them every six months to see what is happening with carbon dioxide, and the point of illness begins in these persons when they begin to retain carbon dioxide at this stage of REM sleep. What we do is start ventilatory support in these stages of sleep in the early stages of the illness.  Because they are going less to the emergency room, costs are reduced for both family and istitutions, and there are less complications in preventing the increase of carbon dioxide, which generates nocturnal and diurnal hypoventilation. What this means is it is feasible and that a good diagnosis of patients with simplified studies can be obtained.

Currently, Dr. Torres is conducting a study in which these patients are followed up with simplified studies here in the laboratory. And the reason this is done here in the laboratory is that this type of patient does not have obstructive apnea regularly,  they do not have a problem in the upper airway obstruction, but have a restrictive muscle problem that prevents them from having the muscular force required to inhale and exhale enough forced air. Therefore, the study is performed here, so that we can validate and conduct the study at home, so patients do not have to come here, and simplify the diagnosis, with an in-depth study of individuals evaluated by specialists, respiratory or clinical specialists in sleep medicine, who use the indispensable tools to select patients. The simplified diagnosis is extraordinary. So I think yes, in sleep laboratories, what has been done here in our country and in the centers where I work, both at UNAM and here at INER, what has been seen, is that the patient is valued comprehensively and this enables us to carry out simplified studies at home. Because we do not have so many patients in the lab, we reduce costs for both patients and institutions. In this way, we bring to sleep clinics only those individuals who have other types of diseases, more complicated diseases, such as ALS (Amyotrophic Lateral Sclerosis), or more complicated neuromuscular patients, or patients with movements associated with sleep. However, the study of simplified sleep is something that greatly helps to reduce time and simplify the diagnosis.

NN: So, in your opinion, is the increase in home studies significant in Mexico? And, how far can home-based studies replace one-on-one type 1 lab tests? In a regular population for a patient who snores and who’s wife tells him that he is not breathing during sleep, or he is simply tired and the next day feels no motivation, the search for a sleep laboratory is necessary.

MLG: It is very important because we currently generate in ourselves many sleep disorders, because we are sacrificing much of our sleep for social reasons, and for work, but above all, for the advancement of technology, because we have within our reach the communication equipment, video games, cell phones, and tablets, and because of this we’re losing our circadian sleep rhythms. I am referring to, for example, the younger generation. There are more and more young people who complain of insomnia or who complain of daytime sleepiness and who can be diagnosed with insomnia. Parents are worried, children or adolescents complain of daytime sleepiness, and of pressure, and what happens is that we are completely altering sleep, because we are always waiting to see if a message has arrived, if someone has posted something on social media and reviewing social networks. What does it do? We know that light is a key factor in inducing sleep. It is the main biological clock to indicate that it is time to go to sleep. But when we have the light stimuli at a very short distance, it creates confusion in the brain and what starts to happen is that we delay sleep, and delay sleep, until we create insomnia. When we want to go to sleep we cannot. Young people become sleepy. And, because staying awake until 1am and the need to awake at 5am, leaves us with only 4 hours of sleep a night, adding to that hours going to and from work. What happens in the return hours, probably due to all the traffic in the big cities, is that we are sleepy in those hours that it takes to return home. Additionally, young people arrive and take a nap for an hour or two, and between 7 and 9 at night they get up to do their tasks and activities, and again at eleven or twelve they go back to bed. We are altering our sleep cycles, and these kids end up taking a hypnotic drug to sleep, because there is no way back to the previous cycle. Or maybe end up compensating for sleep on the weekends, or decide to party on Friday and do not sleep and end up sleeping all morning. Now there are some multicyclic sleep cycles in which people sleep when they can or want. And what happens is that they take hypnotics to sleep or activators of the central nervous system to keep them awake, which is not healthy.

Now, when doing the type 2 studies, we have the possibility to put type 2 equipment on a teenager, and leave it all night, to see how his sleep was, how much he woke up at night, how many activations he had, to see if there is some disturbance related to sleep, and see how well he slept all that night, what time he wakes up, what time he gets up, and how many naps he takes during the day, so that he can give a more precise treatment for his problem, which, more likely, are bad sleeping habits. Now we know that there is an insufficient sleep syndrome and if we do not give a person a sleep inducer, or an activator, I believe that in the long term we will have health consequences. It is important in this type of individual. In what other type of patient is the polysomnography useful? In patients with movement disorders, those with periodic movements, those with sleep-related epilepsy and who are difficult to control, and in those adolescents who have had parasomnias and who again suffer from parasomnias in adolescence and who arrive at the sleep laboratory and do not present any type of parasomnia. They know they will be observed, so it is more difficult for these events to occur in the laboratory and do not respond to the usual treatment of parasomnias. Therefore, in this type of population, doing a type 2 polysomnography at home would be sensational. In addition, in other people who have other comorbidities, and who have no place to perform the polysomnography, or when the service is saturated, a home polysomnography can be done. Also in those who are already being treated and who remain ill, and continue with symptoms, in these patients we can find another type of parasomnias associated mainly to REM sleep when doing a polysomnography at home.

NN: In what aspects should physicians pay close attention to when performing the home polysomnography? I am referring to reading studies, since you are not present in the laboratory, and there is no control of what happens to the patient.

MLG: A prior clinical evaluation is also relevant, it is very important. As we know, there is a high prevalence and a greater study regarding the respiratory disorders associated with sleep. However, there are other disorders, so a comprehensive assessment is needed. There are many tools we can use, questionnaires that tell us that other sleep disorders may be associated with movement disorders, complaints and strange sensations in the extremities. If movements occur in the beginning of sleep, or at the end of sleep, and with all the symptoms that are associated with the patient, this will give us an important guideline.

When the study is done, what should we see? Having a study of more than six hours of recording would be a diagnostic tool. If we do not have a sleep study of at least six hours, it will not work. This is one of the relevant situations. Another is to have at least four hours of sleep in which we have at least two cycles of sleep, NON-REM sleep and REM sleep, that have complete sleep cycles, that oximetry signals are not lost, and we have at least 80% of good quality respiratory signs, and we have a warning button, for example, if there is an event in the patient’s case, we have the option to press the button that sometimes puts them on alert and we see these signs during registration. But something that is fundamental in home studies is a video, which would contribute a lot, and would be a great support in polysomnography studies. But polysomnography without video are fundamental points.  There should be a highly qualified technician who knows the signs and how to identify the artifacts so that when the doctor does the analysis of all the signs that have been registered, he can have reliable signals and high technical quality, to identify which are the bad signals or artifacts. This is critical. In the home studies that we did, for example, an oxygen saturation that does not vary, a saturation of 93 at all times, is an artifact that does not change at any time, having an oximetry of 93 is fundamental. Another artifact that presents itself in this type of study is the presence of a heart rate signal through an oximeter, a signal of 120 beats per minute, which is also a frequent feature that sometimes leads us to alarm. The other tool I have to eliminate this artifact is heart rate. The heart rate signal seen in a home polysomnogram may help me to verify that it is an artifact. I believe that these are fundamental points.  The main objective is to identify the signs of poor quality, and to have a polysomnography of high technical quality, essential points that a doctor should fix.

NN: You had the opportunity to work with Neurovirtual equipment for a while, with the BWIII PSG and BWMini. Could you tell us about your experience with the equipment, as far as  software and  the technical service, as well as experience with Neurovirtual in general?

MLG: Compared to other equipment on the market with the same characteristics, Neurovirtual has many advantages. It has considerable advantages in terms of collection, how to do the study, how easy it is to access the software, how to generate, how to evaluate, how to interpret, how easy it is to visualize events that did not appear before, and how easy it is to generate the reports. But what I love the most is the technical support. Other brands in the market also claim to have such technical support. In fact, I’ve never seen it, but Neurovirtual technical support is the most sensational I’ve ever seen. They solve the issues very quickly. They connect to the machine. To avoid losing the study where you are, they will resolve the problem while you have a network connection. Among the brands of suppliers of polysomnography equipment here in Mexico,  Neurovirtual is the one that has the best technical support. We do not have to call them by phone, and they answer us at any time, whether it is 1am or 5 am. That’s great. It delights me.

I had the opportunity to work with the Mini, the type 2 equipment. I think it is a revolutionary device. We are dedicated to studying any sleep pathology, not only respiratory. However, I am fortunate to work here in this center, which, I dare say, is one of the most important centers in our country that deals with respiratory disorders, which is why they are very interested in arterial blood gas during sleep. The Mini enchants me because I can do a complete study, all the assembly 10-20 and more. Something that I had always asked that could be done in a 2 device is to be able to connect auxiliary signals, electrical signals. What are these signs? For example, carbon dioxide, either aspirated or transcutaneous. Because of the type of population we have here, that is, the hypoventilated patients I mentioned earlier, with some other comorbidities, or the patients hypoventilated by obesity or some other situation, this equipment has the option of connecting an exhaled capnography and  the fact that we can see the sign of the study at home is sensational. It was the best thing they could have done, provide us with this tool, because what we did was take a capnographer to the patient’s home and ask a relative to take notes. This possibility of having direct current signals, seems to me that this is a differential to be able to take this type of technology in home polysomnography, or non-domiciliary polysomnography. For example, patients in hospitals, especially in obese patients who have had a pre-infarction, or who have some other pathology and who are in the hospital, giving them this possibility is sensational. Also patients who have been retained, who have had hypoventilation, who have had carbon dioxide retention all night and who are being treated at home may have this option. I do the study, I can bring the capnograph and do the exams without going to the hospital. This is also very important, that many people do not realize. We do know that a large part of the obese population does not have obstructive apnea. There is a low number of obese people who do not have sleep apnea, only nocturnal hypoventilation. With simplified equipment type 3 we can determine whether the patient has apnea or not, and we can decide to use oxygen if it saturates, and by putting oxygen in place, will they continue to hypoventilate. This is a tool for the respiratory area. For a cardiopneumology, in the respiratory area, this is critical. So I think this gives us a lot more information and we can continue with type 2 home studies, and those individuals who are patients with REM associated parasomnias, especially the elderly people who are at home, we also have the opportunity there. Or in difficult-to-control epilepsies, with long-term studies so you do not have to be in the lab all day or two, but at home. That is critical. It is important to check the impedances, verify that the signals are still of good quality and that the patient can stay connected for several hours. The time the neurologist considers in the case of difficult-to-control epilepsies, those requiring prolonged studies, or making the differential diagnosis with some parasomnias or some other disorders is very important. As for the Neurovirtual Mini, the truth is that I am pleased and grateful to have been offered the opportunity to try it.  I am very delighted.

NN: Would you recommend the brand Neurovirtual/Sleepvirtual to other doctors, especially in the area of sleep, and neurology in general?

MLG: Yes, I would recommend it. In fact, in this center, both here at INER and UNAM, there is a highly specialized course for medical specialists in the field of sleep medicine. So many of them come to me and ask, what kind of equipment would you buy? And I always tell them that it is better to buy a Neurovirtual product. I say when they have a problem, that they call me, or my colleagues. Because if they do not solve the problem, they can contact technical support and resolve the problem. No doubt, I would recommend using any kind of Neurovirtual product, and of course I do.

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