**4. Sleep-related breathing disorders and obstructive sleep apnea**

nurses enabled a greater proportion of asthma patients to be reviewed at no additional cost to the health service, although these findings should not be extrapolated as a thorough costeffectiveness analysis, compared to the comprehensive telemanagement as explained before

Despite the similar moderate evidence either for asthma or COPD, there are some differences when telehealthcare main purposes are compared between the two diseases. While in COPD telemedicine aims to reduce exacerbations or their early detection in order to avoid emergency rooms visits or hospital admissions, in asthma these objectives are usually directed at assuring a better symptoms self-control and adherence to treatment, considering that undertreatment is the most common problem in European asthmatic subjects [46], and its usual presentation at early stages of life. A fitter control of asthma has been reported possibly secondary to the opportunity of register symptoms continually, thus, the patient obtained a more accurate picture of his disease severity and complied to treatment with a closer and efficient selfmonitoring. However, this severity awareness led to an increased number of unscheduled visits and a harmful consumption of inhaled corticosteroids, which increased their adverse effects [47]. In a similar fashion, another study revealed that 43 patients under a mobile telephone interactive self-control system and compared with a control group, presented significantly higher mean daily dosage of either inhaled or systemic corticosteroids during the study period. Nonetheless, this system also demonstrated fewer unscheduled visits to the emergency department; higher peak expiratory flows at 4, 5, and 6 moths; higher FEV1 at 6

Compliance to new technologies is a relevant feature of telemedicine since not all of public health systems can afford them, and there are still underprivileged groups who are not familiar to these sorts of interventions. It seems that telemedicine for asthma is feasible, although when compared to a web based self-management, patients presented higher rates of adherence to the classic paper based strategies of self-control of symptoms and action plans, though other critical feature such as lung function data was not reliable when the patient wrote it down on

In the pediatric population there is also lacking evidence of telemedicine benefit. Telemoni‐ toring of lung function on daily home spirometry in 44 children with professional feedback did not reduce the frequency of exacerbations significantly when compared to conventional treatment, nor the number of unscheduled visits, FEV1, quality of life or use of inhaled corticosteroids [50]. This finding could be explained by the fact that a highly variable peak expiratory flow and FEV1 values at time of symptoms and a complete overlap in distributions between symptoms-free days and at times of symptoms [51], and also by the underpowered

In conclusion, even though telemedicine for asthma seems to be a useful and promising tool for empowering the asthmatic patients in order to guarantee the self-control of the disease, the evidence of its benefit is still unclear. The short follow-ups, the heterogeneity of subjects and the insufficient evidence of its cost-effectiveness, are paramount aspects that restrain the use of telemedicine for asthmatic patients. We advocate for the tailoring treatment to the individual

months; and better quality of life at 3 months after inclusion [48].

[44, 45].

66 Mobile Health Technologies - Theories and Applications

his own [49].

nature of the study.

Speaking of sleep-related breathing disorders, obstructive sleep apnea (OSA) is a prevalent disease that affects approximately 6–7% of global population, although these figures probably underestimate the real OSA prevalence. OSA is a sleep disorder in wich breathing repeatedly stops and starts, which lead to hypoxemia, subsequent arousals, sleep fragmentation, thus, a poor sleep quality in general. The main symptom is excessive daytime sleepiness, and is now acknowledge as an independent cardiovascular risk factor, increasing the probability of presenting hypertension, coronary artery disease, congestive cardiac failure, and stroke [52]. Attended full in-lab polysomnography (PSG) is the gold standard for OSA diagnosis, an expensive test that demands plenty of time as well as fully trained technicians, and that is why simplified sleep data recollection systems have been approved by the scientific societies for patients with high or low pretest probability of OSA, in order to reduce the waiting list for PSG [53]. Despite the increase of accredited sleep units, the demand of sleep studies has also increased over the years considering the prevalence of the disease. Therefore, waiting lists remain long [54]. Finally, continuous positive airway pressure (CPAP) is by far the recom‐ mended treatment for symptomatic or severe OSA, and it is known to reduce cardiovascular death and non-fatal cardiovascular events [55], however, adherence to treatment has been a troublesome factor in such a way that the first year of long-term treatment usually between 25 and 30% of patients drop out the device [56]. Having said this, there have been some efforts to reduce the long waiting lists and increase the rates of CPAP adherence through telemedicine.

Regarding OSA diagnosis, the evidence of telemedicine usefulness is limited. So far, the American Academy of Sleep Medicine has classified the sleep recording devices into four categories. Full-attended in-lab PSG would be type 1; comprehensive portable unattended PSG with a minimum of seven channels (including electroencephalogram, electrooculogram, chin electromyogram, electrocardiogram or heart rate, airflow, respiratory effort, and oxygen saturation) corresponds to type 2; type 3 comprises modified portable systems with a mini‐ mum of four channels monitored, including ventilation or airflow (at least two channels or respiratory movement, or respiratory movement and airflow), heart rate or electrocardiogram, and oxygen saturation comprise; and finally type 4 includes continuous single or dual bioparameters with one or two channels, typically including oxygen saturation or airflow [57]. Despite the limitations of sensor losses that lead to technically inadequate recordings, the inability to assess sleep time duration or the distinction of apneas (central or obstructive), and the vast heterogeneity of sensors and recorders, the studies have confirmed the overall usefulness of type 3 devices, especially if they focus on the outcome which results in earlier access to treatment for the patient, specially those at high-risk of OSA. An alternative to type 3 devices is the home-polysomnography (H-PSG), which enables the home centered care for patients and a complete sleep evaluation allowing the possibility of diagnosing a large panel of sleep disorders. Thus, this H-PSG intends to perform as well as a full-attended PSG though in an unattended surrounding, without continuous supervision. A technician hooks-up the device, and this factor limits the wide us of this technique [58]. Since the loss of data is still a big issue with type 2 or 3 devices, potential future developments include the use of assistive technology and telemedicine to allow real-time remote monitoring.

To enhance the quality of H-PSG signal, real-time telematics data transmission has been tested generating successful and high-fidelity recordings through a cell phone for an easily deployed home monitor device [59], and a failure rate of 11% of telemonitored in-hospital unattended PSG compared to a 23% failure for unattended H-PSG was observed in another study [60]. Moreover, a pilot study, where 90% of recordings were of excellent quality, consisted in a wireless device to obtain real-time remote supervision of H-PSG from the sleep lab [61]. With this amount of evidence, it seems telemedicine for sleep studies recordings is feasible and may be an important step to reduce the failure rates of home devices; however, there are important barriers for implementing telemedicine for sleep studies regularly. Telemonitoring devices are complex as well as their software; hence, incompatibility problems with other computer programs should be expected. Furthermore, the cost-effectiveness of these systems is yet to be determined considering the fact that the home must be equipped with a computer and Internet connection, along with high specifications for computer programs. However, investigations using integrated circuits available on the market (mobile telephony) have been conducted to simplify access to these technologies [62]. Last but not least, there are also problems related to privacy protection and security of medical data transmission [58]. An ongoing telehealth outof-laboratory "Fast Track for Sleep Apnea" program for veterans has been reported, that has helped to relieve clinical load at the central sleep program, improved local access to sleep care, and improved patient satisfaction with health care for sleep-related breathing disorders. Nonetheless, the following challenges have been acknowledged so far: the programs needed to be properly integrated with other data management systems and data storage devices must be interfaced with computers attached to the VA server; data loss; and maintaining quality control using metrics [63]. Either way, further research is required to determine the role of telemedicine in sleep-related breathing disorders diagnosis, especially for OSA.

CPAP has shown to wipe out the adverse effect of severe OSA, especially those effects related to cardiovascular diseases. However, the rates of adherence to CPAP are still far of being acceptable. That is way any measure to achieve CPAP adherence is needed, and new ap‐ proaches such as telemedicine seems to be feasible and cost-effective. Compliance to CPAP is a complex process that involves the participation of the device itself, family support, physi‐ cians, health care personal, sleep unit, and government politics [64]. So far, low-quality evidence justifies the use of supportive interventions added to the usual clinical practice to increase CPAP adherence [65] and, similar to previous items, more clinical trials are called for to clear up the role of these interventions, where telemedicine is included. Earlier works presented contradictory results. A statistically significant higher adherence was found in a telemedicine-guided naïve to CPAP patients recently diagnosed with OSA along with greater satisfaction, concluding that telehealth might be cost-effective for CPAP adherence manage‐ ment [66]; while no differences were found in hours of CPAP use, functional status or client satisfaction in another study [67]. It is worth to mention that these two studies followed the patients for a 12-week and 30 days period, respectively. More recent clinical trials have added some light to the subject. A 12-month telemedicine intervention resulted in a median CPAP usage that was 0.9 h/night higher than that of an attention control group after 6 months, and 2.0 h/night higher after 12 months in a clinical trial including 250 patients, although the median adherence of all patients was low, with 19% of patients refusing the use of CPAP at all [68]. Another clinical trial of 75 patients, showed higher rates of adherence to CPAP after 3 months of telemedicine intervention, which was determined as a significant predictor of adherence, apart from age and sleepiness symptoms measured by the Epworth Sleepiness Scale [69]. Finally, although no difference in hours of CPAP use was found in a study including 139 OSA patients, telemedicine showed to be more cost-effective than the usual face-to-face manage‐ ment, with travel costs and lost work time being the most important sources of savings [70].

Improvement in case detection and the resulting higher healthcare demand has not been accompanied by any real improvement in OSA management. In addition, health resources assigned to OSA and its treatment have been found to be inadequate [71]. Telemedicine is an appealing approach that needs to be explored and taken into consideration in order to obtain a diagnosis and follow-up of sleep-related breathing disorders in a more timely fashion, which would help to achieve the desirable management of these diseases.
