The patient who was scheduled for a sleep study was unusual even by New Mexico standards. New Mexico, the fifth largest state by area, has three “metropolitan centers”—Albuquerque, Santa Fe, and Las Cruces—surrounded by thousands of miles of rural outposts, reservations, and high desert peaks. This case, involving a patient who had been sent home on a ventilator at age 4 and was here now at age 10, never having had her ventilator settings changed in the intervening 6 years, was a little troubling but unfortunately understandable in a state where the nearest hospital can be hundreds of miles away.
How to even begin to know the proper ventilator settings for a child like this could have been a tough problem for Cyndy Fedorovich, RRT, RPSGT, and Lea Davies, MD, the pediatric pulmonologist overseeing the home ventilator clinic at the University of New Mexico (UNM). Luckily, they had a tool that has proved over the last several years to be invaluable in managing pediatric tracheotomy and ventilator patients—the sleep study.
The importance of sleep studies in diagnosis and treatment of the general pediatric population has come to the forefront in the last several years. The problems associated with poor sleep in children are many: poor growth, problems with concentrating and learning, ADD, and ADHD. A lot of resources have been applied and research published demonstrating these links.1
MORE STUDIES NEEDED
For this subset of the home-ventilator pediatric population, however, there is little—if any—research. Furthermore, the use of sleep studies for this population may be far more limited than its anecdotal success suggests it should. What is limiting its implementation? A lack of published research and education of caregivers would certainly top the list. Access to health care centers that have a strong sleep program, which depends so often on a patient’s proximity to an urban center, is probably a necessity. Poor reimbursement for services rendered in the hospital and the economics of caring for children with long-term or chronic problems can always hinder care.
When Fedorovich, now a manager with Embla Sleep Systems, and Naim Bashir, MD, a pediatric pulmonologist now in private practice, started the inpatient pediatric sleep program at UNM Hospital more than 5 years ago, they had little indication of how sleep studies would ultimately benefit their patients. As Bashir relates, “We had so many patients who had needs beyond what an outpatient sleep lab could handle that it was keeping them from having studies. The main emphasis was to get them near the auxiliary care they might need, just so they could safely have a sleep study.”
They soon realized, however, that the sleep study was well suited to helping not just the 10-year-old who had not had her ventilator adjusted in 6 years but also kids seen regularly in the clinic, patients who might be outgrowing their tracheostomy tubes, or patients whose disease process and/or growth might be changing their ventilatory needs.
The sleep study was a strategy that contrasted with the conventional means of setting any patient’s ventilator. Instead of basing settings on a patient’s size and weight or diagnosis and then checking the efficacy of the settings with a blood gas analysis, an oximetry reading, or an ETco2 reading with the patient awake, the sleep study allowed the doctor and the clinician to react to changes and to make adjustments in real time, as the patient slept.
Sleep technologists are trained to look for erratic breathing or sleep effort that causes the patient to wake up. Essentially, for a ventilator sleep study, the technologist is looking for similar things: Is there asynchrony with the ventilator; is the respiratory effort increased; is the patient’s oxygenation poor; are CO2 values elevated; is the ventilator itself autocycling; does there appear to be a leak at the tracheostomy tube, with low exhaled tidal volumes; is the patient uncomfortable, with frequent awakenings and fragmented sleep?
Since these problems appear in real time, it gives the technologist a chance to try different ventilator settings to optimize them for improved ventilation. For low oxygen saturation, the technologist could increase the O2 flow or increase the peak inspiratory pressure (PIP). Likewise, for elevated CO2 levels, the technologist could increase the PIP or the set respiratory rate. For patient discomfort with the ventilator, the technologist could make adjustments to the rise time.
FINDING THE LEAK
Perhaps the most revelatory result of a ventilator sleep study can be the discovery of significant tracheostomy tube leak, which can make the most appropriate ventilator settings ineffectual. Davies is convinced that the problems associated with a poorly sealing tracheostomy tube are often undetected or underappreciated, saying, “There really isn’t a lot of recognition of the problems that a sizeable tracheostomy tube leak can cause with a ventilator. A home ventilator is supposed to be leak compensated, but in reality for children, who tend not to have cuffed tracheostomies, the leak continues to be a problem. Unless you do a sleep study, you probably aren’t even going to be aware of it.”
Recognizing these troublesome tracheostomy leaks on a sleep study and making changes subsequently can lead to dramatic results. Often a repeat study will be done after the tracheostomy tube has been changed to one with a cuff or upsized. With a good seal, appropriate ventilator settings can then be established and verified with appropriate Sao2 levels, normal CO2 readings, patient comfort with the ventilator, and, as a final result, consolidated and normal sleep architecture.
Kids on ventilators can have all the normal problems associated with poor sleep—poor concentration, trouble learning, etc—but because they generally are a more vulnerable population, they have other associated problems: failure to thrive; atelectasis; increased respiratory infections, especially when underventilated. It would make sense that obtaining optimal ventilator settings through sleep studies would lead to an improved quality of life as well as decreased morbidity.
Davies states, “I would now find it difficult to manage my ventilator patients without [sleep studies].” The ability to optimize ventilation, along with the ability to recognize problems such as autocycling or lack of triggering and/or synchronization between patient and ventilator, [provides] additional important information derived from the sleep study. Another area where she feels a sleep study is imperative is in preparing for decannulations, especially in those children who had tracheostomies placed for upper airway obstruction. “There is a certain population of children who may not need a sleep study: for example, the previously well 16-year-old boy who has had a tracheostomy placed because he’s been in a car accident. A common cause for tracheotomies in children, though, is upper airway obstruction, eg, children with craniofacial abnormalities, laryngomalacia, subglottic stenosis. My concern is how do you diagnose ongoing upper airway problems without first doing a sleep study with the tracheostomy capped? I would be very nervous in trying to decannulate this population without the benefit of a sleep study.”
To get to the point where sleep studies for the pediatric population with ventilators or tracheostomies are considered to be the standard of care could be an uphill struggle. For some clinicians, the traditional clinical parameters for ventilator settings may be fine. There has always been a bias against cuffed tracheostomies with children due to the problems of pressure necrosis and stenosis. The advent of “tight to shaft” cuffed tracheostomy tubes has been a great help in this respect, but it might be a while before their use is widely accepted. For more traditional clinicians, an uncuffed tracheostomy tube with a leak may be preferable to any cuffed tracheostomy tube, and a sleep study aimed at minimizing leaks may not be a priority.
Then, too, there may be an argument over whether ventilator settings arrived at when the patient is asleep are going to be the most appropriate for the child throughout the day. Most patients do tend to “ride the vent” during the night; that is, they allow the ventilator to do most of the work for them. Indeed, for Davies that is often the most beneficial thing about ventilators optimized for nocturnal use: The patient’s respiratory muscles get an 8- to 10-hour respite. Children don’t tend to “ride the vent” during the day, however, and there may be a mismatch between the ventilator and the patient’s needs, especially for more active kids.
BARRIERS TO IMPLEMENTATION
Davies reports that at Riley Children’s Hospital in Indianapolis, where she was formerly on staff, there is a protocol in place in which a child will come in to the sleep laboratory during the day and be studied for 4 hours while awake, and then have that followed with a true sleep study while asleep. Then the physician has data for the patient both awake and asleep. Davies believes that protocol might be informative but that, ultimately, having different vent settings—one for the day and another set for the night—just isn’t practical. In addition, a patient’s ventilatory needs during the day are much harder to pin down: “Remember, when the patients are in the sleep lab, they’re sitting in the bed, awake, watching TV, which is going to be different from what they’re going to be doing at home, pushing their wheelchair or playing. We can’t really mimic what they’re doing all the time.”
While a big fan of using sleep studies in her own program, Davies realizes that there are considerations that may keep sleep studies from being the universal standard of care for ventilator patients: 1) the reimbursement economics can be poor for this population, and, to even approach breaking even, a program needs to be able to balance studies run on an outpatient basis, for which there is reimbursement, with inpatient studies, for which there is usually no reimbursement; 2) access to this type of program can be poor, because the economics of these sleep programs and the training of the staff at this point almost predetermine that they will be located in an urban center, where many rural patients will be unable or unwilling to travel; 3) the relatively small population of kids with tracheostomy tubes and/or ventilators may limit the resources that can be devoted to them and, therefore, limit the dispersing of information pertaining to their treatment. Davies laments this reality: “You’re dealing with a small population, spread across America. Some are in large centers, some are in small centers. If you haven’t used or been exposed to sleep studies, you may think what you’re doing is fine. It’s once you experience sleep studies that you start to realize how valuable they can be and you change. I think they go hand in hand: If you’re in a program with a sleep lab, you’ll be doing ventilator studies; if you’re in a program that doesn’t have any sleep exposure, you probably won’t do sleep studies. The population that looks after these kids is so small, we don’t have many dedicated conferences for the care of the chronic, home-ventilated kid. So your ability to meet and discuss these things is limited. If you look at the literature, there probably aren’t a lot of people doing studies or research into kids on vents.”
Lee Brown, MD, is executive medical director of the Program in Sleep Medicine at UNM, as well as a member of the board of directors of AASM (American Academy of Sleep Medicine) and an associate editor of the Journal of Clinical Sleep Medicine. He remembers how long it took sleep programs to get out of neglected basement spaces in most medical centers. He believes the key for the adoption of ventilator studies, as with any new technology or tool, is going to be published research.
“To my knowledge, from my reading of the literature, I don’t see many, if any, clinical research articles talking about inpatient sleep testing and its role in improving outcomes in home ventilator programs for kids. I think a lot of work needs to be done in that regard. I think places like UNM and other places around the country that have pediatric sleep capability are well positioned to provide that research, and in my opinion, when that happens, it will become the standard of care.”
Whit W. Brown, RPSGT, CRT, is staff sleep technologist, Sleep Disorders Center, University of New Mexico. For further information, contact [email protected].
- Fisher BC, ed. Attention Deficit Disorder, Practical Coping Mechanisms. 2nd ed. NY, NY: Informa Healthcare USA; 2007.