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This article provides protocols and indications for the administration of positive airway pressure therapy in the treatment of obstructive sleep apnea. It discusses different treatment modalities, the mechanism of action, and methods for determining optimal CPAP. The recommendations and guidelines by the American Academy of Sleep Medicine are also included.
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Titration Protocols BYAHMAD YOUNESPROFESSOR OF THORACIC MEDICINE Mansoura Faculty of Medicine
INDICATIONS TO TREAT WITH POSITIVE AIRWAY PRESSURE • Administration of positive airway pressure therapy is the treatment of choice for most patients with OSA. • CPAP treatment is generally recommended for all patients with an AHI greater than or equal to 15/hour and for symptomatic patients (eg, excessive daytime sleepiness, insomnia, impaired cognition, mood disorder, hypertension, ischemic heart disease, or stroke) with an AHI between 5–15/hour.
Treatment modalities for positive airway pressure • Continuous positive airway pressure Provides a constant pressure throughout the respiratory cycle • Bi-level positive airway pressure Provides two pressure levels during the respiratory cycle: a higher level during inspiration and a lower pressure during expiration • Autotitrating positive airway pressure Provides variable pressures using device-specific diagnostic and therapeutic algorithms. (Auto CPAP, Auto BPAP ) • Nocturnal noninvasive positive pressure ventilation Provides two pressure levels at a set rate to assist ventilation.
Mechanism of Action • Positive airway pressure, via a fan or turbine generated flow of air, function as a pneumatic splint that maintains the patency of the vulnerable portions of the nasopharyngeal airway. • Positive airway pressure increases nasal pressure above critical pressure ( Pcrit).
Determining optimal CPAP • A variety of methods have been used to determine a single optimal CPAP level. These include: 1. In-laboratory attended polysomnographically guided CPAP titration • Full-night studies. • Split-night studies (consists of an initial diagnostic portion and a subsequent CPAP titration on the same night); 2. Unattended laboratory or home titration 3. Use of autotitrating devices . 4. Formula-derived pressures from clinical, polysomnography (PSG), and/or anthropometric variables
Determining optimal CPAP • The current standard of practice involves an attended pressure titration during a laboratory PSG, during which sleep stages and respiratory variables are monitored. • The goal is to determine a single fixed pressure that eliminates apneas, hypopneas, snoring, and respiratory effort–related arousals (RERAs); maintains adequate oxygen saturation; and improves sleep architecture and quality in all sleep positionsand in all sleep stages. • It is generally accepted that higher pressures are required to reverse airway occlusion during REM sleep and during sleep in a supine position. • Split-night studies can potentially underestimate the severity of OSA
Criteria for split night CPAP titration • At least 2 hours of recorded sleep time during the initial diagnostic portion of the study Apnea-hypopnea indices during the diagnostic portion of the study: AHI >40 OR AHI =20–40 (accompanied by significant oxygen desaturation . • At least 3 hours are available for CPAP titration with the presence of REM sleep during a supine sleep position
American Academy of Sleep Medicine (AASM) recommendations for CPAP and BPAP therapy for adult patients with sleep related breathing disorders • The presence of OSA based on an acceptable diagnostic method should be established prior to CPAP therapy (standard). • Indications for CPAP therapy include: a. Moderate to severe OSA (standard) b. Mild OSA (option) c. Improvement of subjective sleepiness in patients with OSA (standard) d. Improvement of quality of life in patients with OSA (option) e. As an adjunctive therapy to lower blood pressure in patients with OSA (option) • The preferred CPAP titration method to determine optimal positive airway pressure is an in-laboratory, full-night, attended polysomnography, but split-night (initial diagnostic and subsequent titration portion) studies are usually adequate (guideline). • Objective monitoring of CPAP use is recommended to ensure optimal utilization (standard).
American Academy of Sleep Medicine (AASM) recommendations for CPAP and BPAP therapy for adult patients with sleep related breathing disorders • Close monitoring of CPAP utilization and any problems that might develop, especially during the first few weeks of use, is important, as is the correction of problems if needed (standard). • Addition of heated humidification and a systematic educational program enhance adherence to CPAP use (standard). • Patients with OSA treated with CPAP therapy should be followed up yearly or more frequently as needed to correct problems related to its use (option). • CPAP and bilevel positive airway pressure (BPAP) therapy are generally safe with minor adverse effects (standard). • BPAP can be considered as an optional therapy to CPAP in selected patients who require high pressures, who report difficulty exhaling against a fixed CPAP pressure, or who have coexisting central hypoventilation (guideline). • BPAP may also be beneficial in patients with some forms of restrictive lung disease or hypoventilation syndromes with daytime hypercapnia (option).
Beneficial effects of positive airway pressure therapy in OSA Upper airway anatomy and function • Reduction or elimination of upper airway collapse • Reduction or elimination of snoring • Decrease in apnea-hypopnea index (AHI) • Increase in arterial oxygen saturation (SaO2) Sleep quality • Decrease in sleepiness (subjective and objective) • Decrease in number of arousals and improvement in sleep quality . Enhancement of neuro-cognitive function Improvement in mood and quality of life
Beneficial effects of positive airway pressure therapy in OSA • Improvement in driving simulator steering performance . • Improvement in blood pressure and heart rate profiles. • Improvement in cardiac function . • Reversal of the increase in mortality associated with sleep apnea . • Reduction in physician claims and hospital stay
Adverse consequences of positive airway pressure therapy • Aerophagia and gastric distention • Barotrauma (eg, pneumothorax, pneumomediastinum, pneumocephalus) • Chest discomfort and tightness • Claustrophobia, sensation of suffocation or difficulty with exhalation • Eye irritation (conjunctivitis) • Facial skin irritation, rash or abrasion • Mask and mouth leaks • Nasal congestion, dryness, epistaxis or rhinorrhea • Sleep disruption due to noise from the device • Sinus discomfort or pain
Adherence to Positive Airway Pressure Therapy • A large proportion of patients report not being able to tolerate the device. • Self-reports often over estimate actual CPAP use. • Therapeutic adherence in the different studies has varied from 46% to 80% of patients who use CPAP for 4 or more hours nightly on at least 70% of monitored nights. • Factors influencing long-term use include snoring history, severity of illness (AHI), perceived benefit from therapy, and self-reported sleepiness (Epworth Sleepiness Scale [ESS]).
Adherence to Positive Airway Pressure Therapy • Patterns of nightly use are often discernible by the first few days or weeks of initiating treatment . • Adherence to CPAP therapy may be improved with education (eg, additional home visits, participation in group clinics, periodic phone calls to uncover any problems and to encourage use, and even simple written information on the importance of regular CPAP use), airway humidification, proper selection of the CPAP interface, desensitization procedures for CPAP, early follow-up, prompt and aggressive management of adverse effects related to CPAP use, and regular assessment of CPAP adherence.
Techniques that may increase CPAP utilization • CPAP education and support • Humidification • Correction of nasal problems • Nasal vs. full-face masks • Sedative-hypnotics • C-flex • BPAP
Other Modes of Positive Airway Pressure A ) Autotitrating positive airway pressure • Because the required positive airway pressure can differ considerably with sleeping posture and sleep stages, optimal positive airway pressure may have significant intra-night and inte-rnight variability. The causes of this variability are 1-Changes in percentage of REM sleep 2-Changes in percentage of different sleep positions (supine vs. non supine) 3-Changes in nasal resistance (eg, congestion) 4-Use of muscle relaxants, sedatives and opioids . 5-Change in weight
Auto-titrating positive airway pressure (APAP) • Auto-titrating positive airway pressure (APAP) devices automatically and continuously Adjust the delivered pressure, as required, to maintain airway patency. • Pressure is increased if apneas, hypopneas, airflow limitation or snoring are present, or is gradually reduced if no respiratory events are detected over a predetermined period. • These devices have been used to help identify a fixed single pressure for subsequent treatment with a conventional CPAP device (APAP titration) or in a self-adjusting mode for nightly therapy of OSA (APAP treatment).
Auto-titrating positive airway pressure • Studies have shown no significant differences between conventional in-laboratory CPAP titration and APAP titration in reductions of AHI and arousal indices, changes in sleep architecture, oxygenation, or subsequent CPAP acceptance. • APAP treatment has been demonstrated to be comparable to conventional constant-pressure CPAP therapy. • Different devices may utilize different algorithms for monitoring respiratory events (eg, snoring, airflow limitation, apnea-hypopneas, or impedance) and for altering delivered pressures.
Advanced methods of auto-titration • Newer generation devices can increase the IPAP alone in order to ameliorate obstructive events (Auto Bi-level PAP),correct hypoventilation (averaged volume assured pressure support [AVAPS], Intelligent Volume Assured Pressure Support (iVAPS ) or combine Auto Bi-level PAP with auto-CPAP (Auto-trilevel) or combat central apneas in patients with complex sleep apnea (Servo-Ventilation). • Devices may also introduce a back-up rate to prevent central apneas and although in general they are not referred to as APAP devices, they function using similar principles and can be judged as the latest generation of APAP devices .
Autobilevel positive airway pressure with a minimum EPAP of 6 cm H2O and a maximum IPAP of 25 cm H2O.
BiPAP A40 Ventilator • BiPAP A40 comes with well-known and clinically proven Philips Respironics technology such as Auto-Trak, AVAPS and a Dry Box humidifier design. • The device is capable of non invasive and invasive pressure ventilation, up to 40 cmH2O, providing treatment for your chronic respiratory insufficiency patients. • The device features AVAPS-AE, the first fully automatic ventilation mode, designed to help clinicians during titration process, while maintaining comfort and therapy optimization at the lowest pressures.
BiPAP A40 Ventilator • This new innovative ventilation mode helps in providing long term therapy compliance regardless of changes to the body position, sleep stages and respiratory mechanics. • Detachable Battery with up to 5 Hours Backup • AVAPS-AE Automatically Adjust Ventilation to the Patients Need • Compatible with PSG Systems • Optional Oximetry Module • Intuitive, User Friendly & Colored Interface • Integrated Heated Humidifier • Graphical & Statistical Data Management on Encore Pro & Direct View Soft wares
SPECIFICATIONS • Ventilation modes : CPAP, S, S/T, PC, T, AVAPS-AE • Hybrid ventilation AVAPS (Average Volume Assured Pressure Support) AVAPS-AE • IPAP 4 – 40 cm H2O • EPAP 4 – 25 cm H2O • Target tidal volume (when AVAPS enabled) 200 – 1500 ml • Breath rate 0 – 40 bpm (4 – 40 bpm in T mode) • Inspiratory time 0.5 – 3 sec. • Triggering and cycling Auto-Trak ,Sensitive Auto-Trak, Flow triggering. • Rise time 1 (100 ms) – 6 (600 ms) • Size 21.6 cm W x 19 cm L x 11.5 cm H • Weight 2.1 Kgs (with power supply)
SPECIFICATIONS • Humidification System Onehumidity control and ‘Dry Box’ technology • Alarms Patient disconnection Apnea ,Low minute ventilation ,Low tidal volume (with AVAPS/AVAPS-AE only) ,High RR • Monitoring Pressure, tidal volume, minute ventilation, respiratory rate, leak, I/E ratio • Battery back up Detachable battery module: 5 hours • DC power source 12 VDC, 5.0 A (external battery),24 VDC, 4.2 A (power supply) • Data management Encore Pro 2 and Direct View software • Compatible with oximetry module • Advanced detection of residual respiratory events(Obstructed Airway Apnea, Clear Airway Apnea, Hypopnea, Periodic Breathing, RERA, Large Leak and Snore)
Why Alveolar Ventilation? • Gas exchange only occurs at alveolar level • We have a continuous demand for a supply of O2 and removal of CO2 • Conducting airways do NOT participate in gas exchange
Anatomical Dead space • Inspired/expired air remaining in conducting airways • Not involved in gas exchange • Correlation between patient’s height and dead space (Vd) • Height is used to calculate anatomical dead space (Vd) for each breath of air (Tidal Volume) • Example dead space volume (Vd) : 120 ml for height 175 cm or 70 inches
Alveolar Ventilation • Vt (500ml) – Vd (120ml) = alveolar ventilation for one breath • 500 - 120 = 380 ml participates in gas exchange for each breath • Vta x RR (respiratory rate) = Va (minute alveolar ventilation) = 0.380 x 15 = 5.7L/min Benefits Of Alveolar Ventilation • Supply of O2 (PaO2) .Normal = 80 – 100 mm Hg • Removal of CO2 (PaCO2) . Normal = 35 – 45 mm Hg • Alveolar ventilation provides necessary gas exchange to satisfy metabolic demand
As alveolar ventilation drops , iVAPS rapidly increase pressure support until target Va is reached, and as alveolar ventilation increase , iVAPS rapidly decrease pressure support .
Intelligent back up rate (iBR) stays out of the way at 2/3 spontaneous rate whenever the patient spontaneously triggers above 2/3 of the target . once the patient rate reach minimum back up rate (2/3 of the target ) iBR increase towards patient spontaneous rate to maintain alveolar ventilation .Once spontaneous trigering returns, iBR drops back to 2/3 of the target / spontaneous rate.
Auto-TriLevel • The auto-TriLevel principle by Weinmann combines two proven types of therapy – auto-CPAP and BiLevel – into a synthesis that offers the most therapy effectiveness. Your benefits with these products: • Therapeutically effective maximum and mean pressures that are lower than BiLevel with the same tidal volume for fewer side effects such as leakage. • It‘s like a new titration every day – adjusts to patient‘s high variability . • Effortless titration and monitoring .
Auto-TriLevel • IPAP: inspiratory pneumatic splinting of the airways (ventilation) • EPAP: easier exhalation at a low expiratory pressure level for a pleasant breathing sensation • Additional end-expiratory pressure (EEPAP): required minimum pressure for adequate splinting of airways during phase when risk of collapse is highest • PDIFF (Δ IPAP-EPAP): need-oriented ventilation support by means of changes between inspiratory (IPAP) and expiratory (EPAP) pressure levels
Auto-TriLevel • Reduced mean and maximum therapy pressure under TriLevel: Results of a bench test comparison with BiLevel therapy. • SOMNOvent auto-ST is the world‘s first automatic BiLevel device that permits goal-oriented therapy settings(SCOPES). • With the combination of the autoTriLevel principle and the automatic trigger WM trak, this device delivers the greatest effectiveness, reliability and breathing comfort – simply the fastest therapy results. • Particularly for cases of complicated SDB, SOMNOvent auto-S, convinces with its intelligent combination of automatic BiLevel S therapy and auto-CPAP.
Auto-TriLevel • Auto-bilevel spontaneous (SOMNOvent auto-S ). • Auto-bilevel spontaneous/timed (SOMNOvent auto-ST ). • Anti-cyclic modulated ventilation (SOMNOvent auto-CR ).
Stellar provides the following modes: • CPAP mode—a fixed pressure is delivered. • S (Spontaneous) mode—the device senses the patient breath and triggers IPAP in response to an increase in flow, and cycles into EPAP at the end of inspiration. The breath rate and the respiratory pattern will be determined by the patient. • ST (Spontaneous/Timed) or PS (Pressure Support) mode—the device augments any breath initiated by the patient, but will also supply additional breaths should the patient breath rate fall below the clinician's set ’backup’ breath rate. • T (Timed) mode—the fixed breath rate and the fixed inspiration time set by the clinician are supplied regardless of patient effort.
Stellar provides the following modes: • PAC (Pressure Assist Control)—the inspiration time is preset in the PAC mode. There is no spontaneous/flow cycling. The inspiration can be triggered by the patient when respiratory rate is above a preset value, or time triggered breaths will be delivered at the backup breath rate. • iVAPS (intelligent Volume Assured Pressure Support) designed to maintain a preset target alveolar ventilation by monitoring delivered ventilation, adjusting the pressure support and providing an intelligent backup breath automatically. The iVAPS therapy mode is indicated for patients 66 lb (30 kg) and above.
iVAPS (intelligent Volume Assured Pressure Support) • The iVAPS therapy mode is indicated for patients 30 kg and above. • You may prefer some assurance that the patient's ventilatory needs will be maintained if their condition varies. • A variety of ‘dual mode’ schemes exist, that aim to combine the benefits of pressure target and volume target, most of which can be categorized generically as volume assured pressure support, or VAPS modes. • With VAPS devices in general, the ventilatory assistance (pressure support) aims to automatically adjust to changes in patient condition over time, typically to maintain a target tidal volume.
iVAPS (intelligent Volume Assured Pressure Support) • iVAPS offers the comfort and synchrony of pressure support, but with the assurance offered by a volume target. • iVAPS has the following advantages over traditional VAPS schemes: • iVAPS is a unique combination for a servo-controlled ventilator, in that iVAPS has the goal of regulating alveolar ventilation to a prescribed target, and iVAPS has a rapid but gentle servo-control response. • iVAPS is tuned to be fast enough to avoid blood-gas derangement associated with most breathing challenges, including during sleep, but is gentle enough to avoid disruption. • iVAPS has an intelligent Backup Rate (iBR) which aims to keep ‘out of the way’ while the patient is breathing, yet during sustained apnea will mimic the patient's own breath rate.
Pathology Defaults • A choice of disease-specific preset values, based on commonly-used clinical values for obstructive, restrictive , obesity hypoventilation and normal lung mechanics. • Advanced settings are optimized so medical staff can focus on fine-tuning primary settings for each patient. • Before use you will need to review the set parameters on the Clinical Settings screen.
