Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4704_Библиотеки_им_академика_М_И_Перельмана
.pdf
1 Neuro-Stimulator Use in Obstructive Sleep Apnea—Past, Present and Future 17
Wellman A, Malhotra A, Jordan AS, Stevenson KE, Gautam S, White DP (2008) Effect of oxygen
in obstructive sleep apnea: role of loop gain. Respir Physiol Neurobiol 162(2):144–151.
https://
doi.org/10.1016/j.resp.2008.05.019
Woodson BT, Strohl KP, Soose RJ et al (2018) Upper airway stimulation for obstructive sleep
apnea: 5-year outcomes. Otolaryngol Head Neck Surg 159(1):194–202.
https://doi.org/10.1177/
0194599818762383
https://t.me/medicina_free
Chapter 2
Positive Airway Pressure Therapies:
Advances of the Decade
Mashni Alsaeed, Yousef MohamedRabaa Hawsawi,
and Ahmed S. BaHammam
Abstract Positive airway pressure (PAP) devices are becoming the first-choice
therapy for obstructive sleep apnea (OSA) and other sleep-disordered breathing.
Neglecting OSA treatments may result in fatigue, sleepiness, headaches, cerebro-
vascular and cardiovascular diseases, decreased life quality, and increased risk of
motor vehicle accidents. OSA therapy plan includes reducing weight, dental options
such as oral appliance therapy, surgical procedures, and continuous positive airway
pressure (CPAP).
PAP therapy has a significant role in eliminating more complex respiratory
obstru
ctions during sleep, such as Cheyne–Stokes respiration, central sleep apnea
associated with heart failure, and chronic hypoventilation syndromes that require the
use of advanced PAP therapy, such as adaptive servo-ventilation (ASV) and volume
targeted limited pressure ventilation. Identifying patients with complex breathing
disorders during sleep who would benefit from advanced treatment remains an active
research area. Randomized controlled trials indicated that the PAP device could
effectively reduce the apnea and hypopnea index and improve subjective and
objective sleepiness. PAP therapy aims to reach the optimal treatment method to
eliminate recurrent respiratory obstructions that negatively affect patients’ health.
The methods of titrating the device differ according to the severity of respiratory
obstructions or their association with poor pulmonary ventilation. CPAP functions
by a direct pump pushing air into the nasal and oral passageway via a specific mask
M. Alsaeed
Respiratory Care Department and Sleep Disorders Center, King Faisal Specialists Hopsital and
Research Center, Jeddah, Saudi Arabia
Y. M. Hawsawi
Research Center Department, King Faisal Specialist Hospital and Research Center, Jeddah,
Saudi Arabia
A. S. BaHammam (
✉)
The University Sleep Disorders Center, Department of Medicine, College of Medicine, King
Saud University, Riyadh, Saudi Arabia
King Saud University Medical City, King Saud University, Riyadh, Saudi Arabia
e-mail: ashammam@ksu.edu.sa
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023
A. S. BaHammam, M. Hunasikatti (eds.), Sleep Apnea Frontiers, Progress in Sleep
Research,
https://doi.org/10.1007/978-981-99-7901-1_2
19
https://t.me/medicina_free
during sleep. The airflow creates a pressure that works in splinting the airway and
restricting the soft tissue from collapsing. To achieve the goal of using the CPAP
device, the patient must accept the device’s daily use, and the patient’s
noncompliance with the device is one of the obstacles that must be avoided by
introducing techniques that improve the acceptance of the device.
20 M. Alsaeed et al.
However, alternative methods for determining
a PAP device’s optimal pressure—
such as autotitrating PAP (APAP)—have seen significant development over the past
decade. This chapter will discuss the latest developments in the selection of PAP
therapy modes over the past decade, emphasizing the guidelines for their implemen-
tation to achieve significant improvement in respiratory ventilation and clinically
positive outcomes. Furthermore, it will describe the state-of-the-art technology
underpinning contemporary PAP devices.
Keywords Sleep disorders · Noninvasive ventilation · Sleep apnea · Obesity
hypoventilation syndrome · Adaptive servo-ventilation · Auto-C PAP
2.1 Introduction
With the continuous positive airway pressure (CPAP) machine’s discovery by Colin
Sullivan in the early 1980s (Sullivan et al. 1981), sleep medicine has entered a new
era, especially in treating obstructive sleep apnea (OSA). As the device’s effective-
ness has led to an acceleration of interest in this new type of home treatment,
companies have diversified in making devices and developing their capabilities by
introducing the latest technology methods. (BaHammam et al. 2017).
The described air pressure must be adequate to secure the upper airway opening
and improve or remove obstructions in the upper airway to benefit from the PAP
device. To do this, we need to send patients to the sleep disorders laboratory. For the
device to be calibrated according to the presence of obstruction, the sleep study
usually ends with reaching the optimal pressure that normalizes breathing during
sleep (Ahmed and Parthasarathy 2010).
Several PAP device manufacturers work with specific algorithms and equations
to respond to the respiratory system’sairflow changes. Nevertheless, patients usually
respond differently to the respiratory system’s specific breathing patterns, which
may affect tolerance to the device and hence, adherence. Some systems quickly
adapt to the prescribed treatment. Therefore, companies are looking to improve the
airflow mechanism that is fitted to the patient’s breathing.
Since the discovery of PAP devices, various device modes have been developed
to deal with respiratory obstructions or hypoventilation, which have contributed to
improving tolerance and sleep quality.
This chapter discusses new developments in PAP therapy for sleep-related
breathing disorders in the past decade.
https://t.me/medicina_free
2 Positive Airway Pressure Therapies: Advances of the Decade 21
2.1.1 Blowers and Control of Interface Pressure
The invention led by Sullivan and colleagues expanded the use of PAP devices for
OSA treatment. This success has catalyzed the creation of a growing market, with an
increasing number of manufactur ers engaged in producing PAP devices and their
related accessories. This activity drove the evolution of significant advances in PAP
technology.
PAP algorithms are designed to perform multiple functions: they utilize a flow-
generating element (blower) to deliver air, regulate the level of positive pressure
administered to the patient, measure the patient’s airflow, detect respiratory events
during sleep, and estimate the volume of air exchanged per minute as well as any
leakage. The collected information is used to set the patient’s needs for proper
ventilation and normal breathing pattern.
To prevent upper airway collapse during sleep, positive airway pressure devices
apply positive pressure to the airways’ wall during inhalation and exhalation. Indeed,
steady CPAP levels affect airway circuit resistance and gas leakage, especially tidal
volume and breathing frequency.
The main challenge in using a PAP device is to maintain synchronization with the
patient’s spontaneous breathing and, hence adherence. This is done using a sensitive
pressure sensor, motor, and blower with good performance, fast response time, and
lower noise levels.
2.1.2 Flow Generator and Transducers
A PAP device has a microprocessor, pressure sensor, integrated DC motor with
blower, motor controller, flexible tube, and different interface masks (Chen et al.
2012). It also includes transformers that control engine speed, airflow, and pressure
at a fixed point in the flow generator. There is a sensor inside the PAP, not the mask,
so it measures the mask’s expected pressure according to the flow measurements at
different points in the system. The idea behind using sensors is to help control
airflow, pressure, humidity, and temperature and provide a smooth output. During
exhalation, the patient’s breathing is monitored, and outputs that reduce the device’s
internal blower fan flow are sent. Reducing resistance prevents the patient from
feeling a fight against the PAP device while breathing. Thus, the airflow sensor’s
importance is to determine the degree of inhaling and exhaling during a patient’s
breathing cycle.
2.1.3 Advanced Blower Technology
An electronically controlled blower draws in ambient air through a filter and delivers
it to the device outlet port. It is essential to choose a sensitive pressure sensor, motor,
https://t.me/medicina_free
and blower to do a good job, keeping this by making the response fast and less noisy;
the blower speed in the CPAP machine adjusts dynamically in response to the
patient’s breathing requirements.
22 M. Alsaeed et al.
The air flows throu
gh the air filter located at the back (side) of the device by the
activated blower and then is compressed. Lastly, the therapeutic airway pressure is
delivered into the lungs through a tube (an interface mask). The pressure signal is
detected near the mask by the pressure sensor and then entered into themicroprocessor.
2.1.4 Ramping
The ramp is a feature in the PAP devices that allows the device to deliver pressure at
a low point set during a specific period, as the device aims to achieve the set pressure.
For example, if the described and optimal pressure is 12 cmH
2
O, the ramp pressure
may start at 5 cmH
2
O and “escalate” or slowly increase over a preset time. The start-
up pressure and slope time can be controlled. According to the patient’s comfort and
clinical condition, the ramp may be enabled or disabled on the device.
Ramp gen erator: This operating mode allows the PAP device unit to operate
independently of patient effort and provides an increase in PAP pressure. The
technologist initiates this function by starting a switch to bring the function generator
to the circuit. Alternatively, the ramp generator provision can be adjusted to be
directed automatically to the summing amplifier if the patient fails to breathe
automatically for a specified time.
Usually, patients face difficulties when the PAP devices deliver high pressure;
therefore, the ramping system helps the patient to feel more comfortable during
sleep. A new feature by some manufacturers is an auto-ramp, which allows the
system to start at low air pressure while the patient is awake. Once it detects that the
patient has fallen asleep, the ramping will automatically begin to allow pressure to
build up to the prescribed level.
Less noise: Sleep using the PAP is difficult because of the loud noise emitted
from the device, so auto-ramp’s low pressure will provide comfort by maintaining a
soft sound from the device while the patients and bed partner are still awake.
2.1.5 Expiratory Pressure Relief Mechanisms
With the development of PAP devices, manufacturers and developers continue to
add more technological developments that have led to the improvement of technol-
ogies that contribute to pressure relief (such as C-flex® and EPR®) and automatic
adjustment machines (APAP). This technique works by relieving pressure during
early exhalation. At the same time, APAP may reduce the average optimal pressure
required to treat sleep-disordered breathing (SDB), thus reducing the side effects and
discomfort associated with the high pressure of the device. Nevertheless, despite
https://t.me/medicina_free
these technological advances and theoretical advantages of these devices for con-
trolling SDB compared to constant pressure CPAP, studies have not conclusively
shown an improvement in adheren ce (Ip et al. 2012).
2 Positive Airway Pressure Therapies: Advances of the Decade 23
As the technology advances for PAP device
s, manufacturers continue to add
further improvements that have led to the development of technologies that contrib-
ute to pressure relief (such as C-flex® and EPR®) and automatic adjustment
machines such as APAP. This technique operates by decreasing pressure during
early exhalation, while APAP may reduce the average optimal pressure required to
treat SDB. Despite the technological advances and the effectiveness of these devices
to control SDB related to continuous positive airway pressure, studies conclusively
show no improvement in the patient’s compliance.
The transformers monitor the motor speed, airflow, and pressure at a fi xed point
downstream of the flow generator. The sensor is located inside the device and not in
the mask, so the device must calculate the mask’s expected pressure based on the
flow measurements at different points in the system. The pressure varies at two
points with the flow that can be calculated, and the length and diameter of the tube
and the characteristics of the mask affect the conti nuous value (BaHammam et al.
2017), so the technical specialist must specify some measurements and enter them
into the device settings such as the type of mask and tube for the microprocessor to
perform the correct calculations.
The microprocessor modifies the blower speed in response to pressure variations
secondary to leaks or regular air pressure changes due to breathing. The flow signal
is sent through low- and high-pass filters to separate the artifacts’ respiratory flow
signal. Low-pass filters exclude the flow of large rapid deflections (e.g., coughing or
sneezing), and high-pass filters exclude cardiac fluctuations. The feedback limits
determine whether the flow or pressure exceeds the expected range of flow change at
a particular motor speed (e.g., tube fracture) and prevent the device from delivering
too much or too little pressure (Chen et al. 2012). As the altitude increases, the fan
speed needs to be increased to maintain the same pressure (Patil et al. 2019, Patz
et al.
2010). Several devices are automatically adjusted to the height.
2.1.5.1 Leak Compensation
While using noninvasive ventilation; air leakage is one of the main factors that must
be compensated for. Air leakage significantly impacts PAP devices’ performance,
affects the pressure to be delivered to the patient, and influences the cycle and
operating thresholds and respiratory events identification.
Leakage Compensation Mechanism
The leakage compensation is done through the flow control and continuously
searches for deviations from the expected flow of breathing, and therefore, there
are differences in engine speed to compensate for air leakage. Because there are
https://t.me/medicina_free
common variations in a patient’s breathing cycle, the average expected leakage is
usually calculated over several breaths. If the leakage is high, the automatic devices
compensate by lowering the pressure, and this will seal the mask and reduce leakage.
24 M. Alsaeed et al.
Leakage can be managed from the flow rate
at the end of exhalation (Stieglitz
et al.
2020). Intentional leakage includes the exhala tion ports on the mask, which
vary according to the type of mask and pressure level, and unintentional leakage
includes leakage from the mouth or around the mask (Al Otair and BaHammam
2020). Generally, the leakage should be less than 24 L/min in nasal masks and less
than 36 L/min in full-face masks, but this may vary depending on the used interface.
The lips and tongue sometimes work as a one-way valve opening during exha-
lation, when pharyngeal pressure is at its highest. This procedure is called valve
leakage or exhalation. Exhalation puffs may incorrectly indicate a flow restriction,
which could cause the robotic devices to increase the pressure unnecessarily (Jaffuel
et al.
2020).
2.1.5.2 Respiratory Cycle Determination
It is essential to define inhalation and exhalation cycles to provide a two-level PAP,
relieve expiratory pressure, and resolve automatic algorithms’ inhalation flow lim-
itations. The critical mark is the beginning of the breathing from the negative flow to
the positive flow—the flow signal switches from positive to negative flow at the start
of the expiration.
Servo-ventilators and some auto devices use a continuous definition of the
breathing cycle. The Res Med servo-ventilat or microprocessor uses vague inference
rules that look at the direction of flow rate and volume to determine the respiratory
cycle stage. Using the Respironics ventilator servo device divides breaths into short
periods (64 ms) to determine the average inspiration expected at other points of the
cycle is determined by the length of exhale to predict the duration of breathing
(Johnson and Johnson 2015).
2.1.5.3 Other PAP Features
Built-in Software
Several PAP devices demonstrate standard therapy statistics on the onboard display,
and others have optional advanced data tracking available through an optional
software program. Some of these programs are available on physical disks and
require download cables from the machine to a computer, while others are down-
loadable programs and can be used with the data cable added to the device.
Recent home PAP devices are equipped with built-in software that provides data
such as compliance, estimates of leaks, tidal volumes, minute ventilation, respiratory
rates, and apnea-hypopnea indexes.
https://t.me/medicina_free
2 Positive Airway Pressure Therapies: Advances of the Decade 25
2.1.5.4 Data Collection and Display
Manufacturers have implemented new technology for PAP therapy data downloads.
In addition to added ease, new transmission systems help deliver more reliable
interaction between the patient, the treatment provider, the insurance company,
and the home medi cal equipment (HME) company. In different cases, they also
encourage patients with OSA to play an active role in monitoring their progress.
New software and apps that sync with CPAP devices offer unique insights into
sleeping patterns, potential mask leaks, and any overnight pressure fluctuations ,
allowing suitable therapy to accommodate individual needs, data that were previ-
ously only obtainable for sleep specialists to evaluate. Many machines can view
minute-by-minute reports; other machines can create day-by-day reports.
2.1.5.5 Noninvasive Positive Airway Pressure (PAP) Ventilatory Modes
The first generation of PAP machines was simple continuous pressure. However, the
need to expand technology development enabled manufacturers to add bilevel flow
generator devices to increase PAP devices’ proper utilization.
2.1.5.6 Continuous Positive Airway (CPAP)
OSA is a partial or complete blockage of the upper airway that causes frequent and
reversible oxygen saturation in the blood and leads to sleep interruption. OSA affects
9% of middle-aged men and 3% of women in North America. If left untreated, it
leads to fatigue, drowsiness, headaches, heart disease, blood vessels, lower quality of
life, and increased risk of car accidents. OSA is determined by several measurements
that are diagnosed by polysomnography, such as the apnea-hypopnea index (AHI),
arousal index (AI), minimal oxygen saturation (SpO
2
), desaturation index, and time
spent with SpO
2
< 90%. Neurobehavioral and OSA are linked with disease states
indicated by a reduced Epworth sleepiness score (ESS), quality of life (QoL), and
increased cardiovascular disease (Patil et al. 2019).
The OSA treatment plan includes a wide range of decisions, such as diet and
lifestyle changes, drug therapy, constant air pressure (CPAP), and various oral
devices to ensure an upper airway splint and surgical treatment.
CPAP is the standard treatment for OSA and includes a pump to deliver air into
the nose or mouth and a mask during sleep. Positive pressure is created from the
airflow, which opens the airway and limits soft tissues from collapse. CPAP’s
effectiveness is limited by low adherence rates, which underscores the importance
of determining adherence boundaries and dealing with optimal pressure to reinforce
adherence.
Most devices apply CPAP in pressure settings between 4 and 20 cmH
2
O. CPAP
pressure of 4 cmH
2
O is the lowest pressure required to provide adequate flow to
https://t.me/medicina_free
clear the device’s dead space, tubes, and airways to prevent rebreathing of exhaled
air. CPAP aims to increase upper airway pressure to produce an airway spli nt to open
up an airway that might collapse during inhalation. Usually, the pressure is adjusted
to eliminate impaired breathing, obstructive respiratory events, snoring, reduced
flow, and insomnia. By providing positive end-expiratory pressure with the required
pressure, CPAP may recruit the alveoli and impro
ve ventilation.
26 M. Alsaeed et al.
2.1.5.7 Bilevel Positive Airway
Pressure (BPAP)
BPAP affords two ways of pressure delivery, high pressure in inhalation and low
pressure in exhalation. A theoretical advantage of BPAP (Patil et al., 2019) was that
the lower set of expiratory PAP (EPAP) is tolerable and may increase PAP treatment
acceptance. With advances in technology, flow sensors have been integrated into
PAP devices to detect obstructive events. BPAP pressures typically fluctuate from a
minimum EPAP of 4 cmH
2
O to a maximum inspiratory PAP (IPAP) of 25–-
30 cmH
2
O. Most devices use a streaming engine to determine when to shift to
IPAP. The trigger is set above zero flow to sense efforts from the patient. Various
technologies are used, including flow, shape, and volume, to navigate EPAP to
reduce desynchronization. The flow cycle algorithm switches to EPAP when the
flow falls below a percentage of the peak flow; Thus, the patient will not experience
exhalation of resistance. Airflow starts high to approach the targeted pressure
rapidly, then gradual ly decreases as the airway pressure inside the alveoli builds
up. Once a predefined percentage of the maximum inspiratory flow is reached
(usually 25%), the expiratory valve opens, and the inspiratory cycle is terminated.
Several parameters can be adjusted with pressure support ventilation, including the
trigger-on threshold, the inspiratory rise time, the pressure level, and in some
ventilators, the cycling-off airflow threshold (Al Otair and BaHammam
2020).
There is significant variation among PAP devices regarding how quickly pressure
levels are reached and whether the device becomes a late or early cycle, particularly
in leakage cases. Patients may experience discomfort if the device's cycle control is
not synchronized with their respiratory cycle.
In conventional BPAP devices, the motor alternates between higher and lower
pressure settings to match the patient’s breathing cycle. Engine acceleration as the
device moved from lower pressure to higher pressure, changing synchronization,
and bearing. One way to enhance comfort is allowing the blower motor to rotate
when moving between inspiratory and finish smoothly. More modern BPAP devices
allow for a smoother change in pressure, and the waveform can be square, expo-
nential, sloping, or sinusoidal. Generally, BPAP offers a standing wave of pressure
support, but manual or automatic adjustments can make the pressure change more
smoothly, helping with comfort (Fig. 2.1). Many BPAP devices allow changing the
elevation time (angle of the extent of pressure change).
Some BPAP devices include cycle settings, trigger, inspiration time, and eleva-
tion time, which can be used to improve efficacy and patient comfort, especially for
patients with COPD or neuromuscular disorders. Consider the ascent time should be
https://t.me/medicina_free
shorter in COPD patients to allow the lungs to fill more quickly and enough time to
exhale. The prolonged rise time in patients with neuromuscular impairment helps
ensure proper tidal volume and gas exchange.
2 Positive Airway Pressure Therapies: Advances of the Decade 27
Fig. 2.1 This illustration shows the pressure and flow waves of pressure support. Cycling-off starts
when airflow reaches a preset threshold, which is a preset percentage of maximal airflow (usually
25%). At this point, the ventilator stops delivering inspiratory flow, the expiratory valve opens to
allow passive exhalation, and pressure goes down to the set positive end-expiratory pressure.
Increasing the cycling-off preset percentage of maximal airflow results in decreasing the inspiratory
cycle. The illustration demonstrates two cycles; one of them has a cycling-off preset percentage of
maximal airflow of 25%, and the other is 50%. The inspiratory time is shorter by 50%, and hence
the delivered tidal volume
2.1.6 Advanced PAP Modes
One of the most challenging approaches to maintaining patients’ compliance and
adherence while using PAP therapy is getting PAP more comfortable. The technol-
ogy underpinning PAP devices has advanced progressively, aiming to increase
patient comfort and potentially boost adherence to treatment.
Technologies related to PAP systems have evolved from a simple pump that
pushes air into the respiratory tract during inhalation and exhalation to develop
technical additions that improve the device’s performance in providing comfort to
the patient and treating complex sleep-related breathing disorders.
It introduced features that control the amount of air and the appropriate pressures
and mechanisms, such as:
https://t.me/medicina_free
Соседние файлы в папке Библиотека им академика М.И. Перельмана