All About Positive Airway Pressure (PAP) Therapy Nitipatana Chierakul Division of Respiratory Disease and Tuberculosis, Department of Medicine, Siriraj Medical School
Siriraj Sleep Center: Fiscal-year 2018 Profiles Activity Number PSG 1,620 New PAP 1,062 MPAP 625 (14) APAP 427 BiPAP 10 (7) Accessory 1,546 Mask 468 Humidifier 55 Daytime visit 15,954
Positive Airway Pressure (PAP) Continuous PAP (CPAP) is standard therapy for patients with OSA Deliver positive pressure to the upper airway via interfaces, serving as a pneumatic splint to prevent collapse during sleep After invented for nearly 40 years, newer generation can recognize and differentiate SDB events, ramp, adjust counter balance output, monitor usage, communicate, and slim (0.5 vs 7 kg)
Autotitrating CPAP (APAP) Continuous pressure self-adjustment based on analysis of flow amplitude reductions, inspiratory flow limitation, (snoring, cardiac artifacts, forced oscillation for OSA vs CSA) Contraindicated in Congestive heart failure Other respiratory diseases especially COPD Daytime hypoxemia/hypercapnia Other causes of especially OHS Central sleep apnea Provide lower mean airway pressure but potentially higher peak airway pressure as compared to fixed CPAP, proper mask fitting is crucial
APAP Certain APAP devices (display 95 th percentile pressure, leaks, AHI, and store > 1 night data) may be used to determine a fixed CPAP pressure for patients with moderate to severe OSA without contraindications Those being treated with fixed CPAP on the basis of APAP titration or being treated with APAP, must have close clinical follow-up to determine treatment effectiveness and safety Reevaluation and, if necessary, a standard attended CPAP titration should be performed if symptoms do not resolve or the APAP treatment otherwise appears to lack efficacy
Phenotypic APAP Respond faster and fine tune to small flow limitation in female Detection of expiratory puffs (oral venting) Autotrial mode for transition to fixed pressure Automatic pressure adjustment (CPAP check) Expiratory relief to compensate discomfort from exhalation at higher lung volume Lowering pressure in periods of irregular breathing associated wakefulness
PAP Interface Proper fitting and comfortable also determines compliance Consider: facial size and shape, hairstyle, nasal figure, claustrophobia, tendency for mouth breathing, cranial deformity Plastic material and silicone components Smaller interface Less obtrusive headgear Expiratory noise reduction Limited parts for cleaning and servicing
PAP Humidification Dry air can lead to mucosal burning/ congestion, nasal dripping and slippage Integrated humidifier instead of in-line, external humidifier Self adjustable level of humidity and ambient humidity sensor Heated tubing minimizes the temperature drop and condensation Smaller water storage is a limitation for higher humidity need In-line heat and moisture exchanger (HME)
PAP Compliance Systematic educational programs are recommended to improve utilization Usage should be monitored subjectively and objectively Transfer large sets of data (compliance, leak, AHI) manually or online/cloudbased Initial follow-up is recommended during the first few weeks to establish utilization pattern and provide remediation Longer-term follow-up is recommended yearly or as needed to address mask, machine, or usage problems
Strategy for Enhancing PAP Use Systematic education about health consequences of OSA Fit and comfort interface Aggressive nasal congestion treatment Humidifier or heated humidifier Frequent contact and followup initially Spouse involvement Immediate intervention for side-effects or discomforts
Handle Adverse Effects of PAP Adverse effects Dry nose/mouth Nasal congestion Bruise Aerophagia Difficult exhale Management Reassure Intra nasal steroid Heated humidification Protective padding Different interfaces Reassure, antacids Interface Different machines
Residual Sleepiness after Adequate PAP Use Suboptimal pressure Suboptimal treatment adherence Insufficient sleep time Presence of other sleep disorders Drugs or substances use and abuse Permanent hypoxic damage of brain areas involved in alertness Somnogenic cytokines released from visceral adipose tissue Adjunctive modafinil in those without obvious causes
How PAP works in CSA Raising lung volume, thereby increasing lung O 2 reservoir and thus dampening fluctuations in PaO 2 Reducing lung water and thus pulmonary irritant receptor stimulation Reducing ventilation and allowing PaCO 2 to rise above the apnea threshold Increases left ventricular ejection fraction, reduces mitral regurgitation, and decreases sympathetic nervous system activity Trial of CPAP may be given for CSA-CSB, should be stopped if AHI remains > 15 because potential harm
Adaptive Servoventilation (ASV) PAP specifically designed to alleviate CSA-CSB analogous to a cardiac pacemaker When central apnea is detected, it provides intermittent PSV But when it detects spontaneous breath, inspiratory assist is turned off In patients with CHF and CSA-CSB, it causes a greater fall in the AHI than CPAP, BiPAP, or supplemental O 2 Increased mortality in HFrEF (< 45%) may result from outdated machine
OSA Treatment options for CSA CSA CSA n heart failure Idiopathic periodic respiration Opioidinduced sleep apnea Stroke, renal failure, other comorbidities Optimal cardiac treatment CPAP Reduction/ withdrawal of opioids? Optimal therapy of underlying disease LVEF < 45% LVEFR > 45% Persistent CSA AHI > 15 AHI <15 Persistent CSA AHI > 15 AHI <15 Persistent CSA AHI > 15 AHI <15 Predominant OSA Predominant CSA Persistent CSA AHI >15 ASV CPAP CPAP CPAP Severe symptoms Minor symptoms CPAP Persistent CSA AHI > 15 AHI <15 Persistent CSA AHI AHI <15 Persistent CSA AHI >15 AHI <15 CPAP Continuing heart failure therapy Persistent CSA AHI >15 ASV ASV ASV ASV Eur Resp J 2017; 49: 1600959
Practice Parameters for the Use of CPAP and BPAP Devices to Treat Adult Patients with Sleep-Related Breathing Disorders (AASM 2006) While the literature mainly supports CPAP therapy, BiPAP is an optional therapy in some cases where high pressure is needed and the patient experiences difficulty exhaling against a fixed pressure or coexisting central hypoventilation is present (Guideline) BiPAP may be useful in treating some forms of restrictive lung disease or hypoventilation syndromes associated with daytime hypercapnia (Option)
Pressure Pressure-Time Waveform of BiPAP IPAP EPAP Trigger Inspiratory Time Rise time Cycle Vt EPAP/IPAP: end-expiratory/inspiratory PAP Trigger: switch from EPAP to IPAP Rise time: transition from initial to peak inspiratory pressure Inspiratory time: time spends in IPAP Cycle: switch from IPAP to EPAP Time T mode: time-triggered or mandatory breath, initiated by the device based on preset backup RR p T S T S mode: spontaneous or flow-triggered breath, initiate by patient generating flow above the preset flow threshold and the device switch from EPAP to IPAP S/T mode: spontaneous-timed mode, patient can initiate breath, the device will add up some mandatory breaths
Variables of BiPAP p T Rise time: in millisecond or the lower number the faster the rise p T Inspiratory time (Ti): set time limit for inhalation by IPAP, may apply to T only or S/T mode
Ti min Ti max Variables of BiPAP P Cycle Window Cycle is set to limit IPAP support Flow cycle: terminate by flow reduction, cycle sensitivity sets the inspiratory flow below peak flow Ti Time cycle: based on Ti settings
Respiratory Rate Pressure Pressure IPAP Spontaneous (S) Mode Spontaneous IPAP Spontaneous Cycle Cycle EPAP EPAP EPAP Spontaneous Trigger Spontaneous Trigger 0 Respiratory Cycle Time (sec) Respiratory Cycle Timed (T) Mode Ti Time IPAP Ti Time IPAP EPAP EPAP EPAP 0 Device Trigger Time (sec) Device Trigger
Pressure Pressure Spontaneous-Timed (S/T) Mode IPAP Spontaneous Ti Time IPAP Cycle EPAP EPAP EPAP 0 Spontaneous Trigger Device Trigger < 60/X < 60/X Respiratory Cycle Back up rate (BUR) = X Time (sec) Pressure Control (PC) Mode Ti Time IPAP Ti Time IPAP EPAP EPAP EPAP 0 Spontaneous Trigger < 60/X < 60/X Back up rate (BUR) = X Time (sec) Device Trigger
Respiratory Rate Volume Pressure Assured volume assured pressure support (AVAPS) Target RR Volume Target V t Ti Ti Min. Max. Spontaneous Ti IPAP V t Device Ti IPAP Ti Ti Min. Max. EPAP EPAP EPAP <60/X Flow Trigger Back up rate (BUR) = X Time >60/X Device Trigger Intelligent volume assured pressure support (ivaps)
Overnight monitoring to establish the nature of the sleep breathing abnormality REPTITIVE OBSTRUCTIVE APNEA OBSTRUCTIVE HYPOVENTILATION ISOLATED SLEEP HYPOVENTILATION Titrate CPAP to eliminate obstructive apneas, hypopneas, and flow limitation Set BPAP Prescribe CPAP Monitor closely: Adherence Follow-up 2 mo Resolution of Hypercapnia CPAP Yes Yes Maintains SpO 2 > 88% increase in TcCO 2 < 10mmHg No CONTINUE BPAP CONTINUE CPAP IF INITIAL AHI HIGH Sleep Med Clin 2017; 12;587-596 Fixed pressure EPAP for UAO IPAP to improve SpO 2 / CO 2 Aim for V T 8-10mg/kg IBW Fixed pressure EPAP for UAO or set AE 5-12 cmh 2 O Target V T 8-10mg/kg IBW Set PS MIN 4cmH 2 O, PS MAX 15cmH 2 O Monitor closely: Adherence, detailed data download from device Follow up 1-2 mo Yes Resolution of Hypercapnia ADJUNCTIVE THERAPIES INCL WEIGHT LOSS, PULMONARY REHAB, SURGERY No RETITRATE BPAP
Suggested Readings New approaches to positive airway pressure treatment in obstructive sleep apnea. Sleep Med Clin 2016;11:153-9 Positive airway pressure device technology past and present. Sleep Med Clin 2107;12:501-15. Choosing the right interface for positive airway pressure therapy in patients with obstructive sleep apnea. Sleep Breath 2017;21:569-75. Definition, discrimination, diagnosis and treatment of central breathing disturbances during sleep. Eur Resp J 2017; 49: 1600959 Initiation of noninvasive ventilation for sleep related hypoventilation disorders: advanced modes and devices. Chest 2018; 153(1):251-65
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