1. الله الذي جعل لكم الليل لتسكنوا فيه والنهار مبصرا إن الله لذو فضل على الناس ولكن أكثر الناس لا يشكرون) غافر 61  صدق الله العظيم

2. Principles of CPAP BY AHMAD YOUNES PROFESSOR OF THORACIC MEDICINE
Mansoura Faculty of Medicine

3. Hectopascals (hPa) ≈ 0.73 mmHg ≈ 0.73 torr
Definition of CPAP = Contuous positive airway pressure (above atmospheric pressure)during both inspiration and expiration.
Atmospheric pressure =It is the pressure around us (weight of earth's atmosphere creates 'air pressure', which we don't feel because it's evenly distributed throughout our lungs ) wherever we are, at sea level or the top of a high mountain.
1 atmosphere (atm) =1.013 bar
= 76o mmHg = 76o torr
1cmH2o = 0.98 mbar or
Hectopascals (hPa) ≈ 0.73 mmHg
≈ 0.73 torr

4. The atmospheric pressure decreases with altitude

5. Altitude I = less than 2500 ft. / <762 m
2 = 2500 to 5000 ft. | 763 to 1524 m
3 = 5001 to 7500 ft. | 1525 to 2286 m
NOTE: Manual adjustment of altitude is not featured on units where there is the Automatic Altitude Adjustment / Leak Compensation feature .eg. Your IntelliPAP automatically compensates for changes in altitude between sea level and 9000 ft (2750 m). You do not need to make adjustments to the device for changes in altitude.

6. CPAP was first described in 1981.
A portable flow generator produces pressurised air which the patient breathes via a closely fitting nasal or face mask during sleep.
System comprises – blower unit, flexible hose (usually 2m), mask with exhalation port(s) and head straps
Room air drawn into machine,through dust filter, and blown out at a pre-set pressure

7. Pneumatic splint operating to keep airway open
Mechanism of CPAP treatment
Air pressure open and
splints the pharyngeal walls
so preventing narrowing and
collapse thereby restoring nocturnal breathing to normal.
Pneumatic splint operating to keep airway open

10. Mechanism of CPAP treatment
When CPAP is applied, all airway obstruction (retropalatal , retroglossal and hypopharyngeal ) are thought to be addressed adequately. Consequently , factors such as the location and pattern of airway collapse are oftentimes ignored when CPAP therapy is initiated.

11. Mechanisms of breathing
We breathe by contracting respiratory muscles (mainly the diaphragms) to expand the thorax and thereby create a slightly negative airway pressure relative to ambient pressure.
This slightly negative pressure -- about
-3 cm H2O at rest -- allows fresh air to enter our lungs and supply the blood with oxygen.Then we relax the respiratory muscles, and in so doing exhale to create a slightly positive pressure relative to ambient (+3 cm H2O); this allows stale air full of carbon dioxide to leave our lungs and enter the atmosphere.

12. To simplify the numbers for these pressure changes we always reference ambient pressure to zero. This has two great advantages:
1-We don't have to use large numbers to show the change in airway pressures during breathing; 2-Though the ambient pressure changes with altitude (lower the higher up you go), zero as the reference point can be used at any pressure. In other words, since the ambient pressure is distributed evenly though out our lungs, zero can be the reference point for any altitude.

13. CPAP expose the patient to an airway pressure above the atmospheric pressure, which is always referenced to zero.
A CPAP of 5 cm H2O means the patient is continually breathing against an airway pressure 5 cm H2O above the atmospheric or 'zero' pressure.
The pressure curve looks the same as if breathing at atmospheric pressure, so that inspiratory and expiratory pressure are still below and above the baseline, respectively.

14. Top: Normal pressure curve (pressure measured at the mouth level) breathing at atmospheric ("0") pressure; airway pressure -3 cm H2O at peak of inspiration (I) +3 cm H2O at peak of expiration (E).
Bottom: Pressure curve when CPAP = 5 cm H2O; the baseline pressure against which the patient breathes is raised 5 cm H2O above atmospheric pressure.

15. CPAP as the name implies, requires the airway pressure to be constant between inspiration and expiration.
Such a pressure is achieved by a servo-controlled air compressor that maintains the airway pressure as closely to the prescribed pressure despite the pull (inspiration) and push (exhalation) of the patient.
The maintenance of such pressure within an FDA-specified pressure range (for example, ± 1.5 cm H2O of the set pressure) is necessary as a quality-assurance measure that would ensure that the device maintains a certain prescription pressure for the patient.

16. Physiological effects of CPAP
splints the upper airway (black crosses and arrows), achieves positive intra-thoracic pressure (white crosses), decreases venous return, increases lung volume, decreases after- load, and can increase cardiac output. The bidirectional vertical arrows signify the traction on the upper airways affected by the increase in end-expiratory lung volume. Such a traction effect can assist in the splinting open of the upper airway.

17. TYPES OF CPAP Fixed CPAP for chronic treatment.
Automatic CPAP has two large uses:
A-Auto-titration PAP to determine an effective fixed level of continuous positive airway pressure (CPAP)
B-Auto-adjusting PAP for chronic treatment.
APAP devices may be initiated and used in the auto-adjusting mode for unattended treatment of patients with moderate to severe OSA without significant comorbidities (CHF, COPD, central sleep apnea syndromes, or hypoventilation syndromes).

19. CPAP treatment
Non-acute setting: Treatment of obstructive sleep apnea , some cases of central sleep apnea eg. associated with heart failure .
Acute setting: Pulmonary edema or COPD exacerbation, when there is hypoxemia but not CO2 retention.
NOTE : CPAP is not a mode of ventilation.

20. CPAP machine

21. Ramp Most CPAP devices, allow the patient to trigger the ramp option.
In the ramp option, the pressure starts at a preset level—usually a low level of CPAP—and then slowly increases to the treatment pressure (CPAP) over the set ramp time
Weinmann devices offer soft start .
DeVilbiss IntelliPAP® offer delay .
Some APAP devices have a “settling time” at a low pressure before the device starts auto-adjusting pressure.

23. Flexible Pressure
Many manufacturers of PAP devices have developed flexible PAP 1- Philips-Respironics provide several comfort options (Cflex, Cflex+, and Aflex) 2- ResMed devices offer expiratory pressure relief (EPR). 3- Weinmann devices offer Soft positive airway pressure (PAP). 4- DeVilbiss IntelliPAP® offer rounding

25. Humidification
Most CPAP devices come with the option of an integrated heated humidification system.
Heated humidity can deliver a greater level of moisture than cool humidification and may be especially useful in patients with mouth leak or nasal congestion.
Mouth leak can cause a dramatic fall in relative humidity and a loss of humidity from the upper airway/CPAP system, thus drying the nasal or oral mucosa.
Use of heated humidification is recommended to improve CPAP utilization.

26. AIR FILTERS
The device uses a gray foam filter that is washable , reusable and screens out normal household dust and pollens,, and an optional white ultra-fine filter that is disposable. the optional ultra-fine filter provides more complete filtration of very fine particles.
The gray reusable filter must be in place at all times when the device is operating.
The white ultra-fine filter is recommended for people who are sensitive to small particles.

27. How is the pressure applied non-invasively?
Via a tight fitting mask attached in such a way that air can be blown into the nose or the nose and mouth.
The mask connects to a hose that is attached to a CPAP machine .
Generally there are 3 types: nasal mask, nasal pillows, and full face mask.

28. The nasal mask (left) and nasal pillows (middle) and full face mask (left)

29. Examples of commercially available chin straps.

31. Forehead spacer designs to decrease the risk of facial skin breakdown
Forehead spacer designs to decrease the risk of facial skin breakdown. Left : Gel spacer. Center: Foam spacer. Right: Adjustable forehead arm.  

32. Facial skin breakdown secondary to mask used for noninvasive positive-pressure ventilation.

33. Rebreathing
In a lung-model study, a lower volume of rebreathed CO2 with the exhalation port in the mask is found as compared to the exhalation port in the circuit. also an oro-nasal mask with the exhalation port in the mask decreased the total dynamic dead space, compared to having the leak port in the circuit.
With a nasal mask, the patient can exhale through the mouth, which should decrease rebreathing.

34. Separate exhalation device or exhalation port in the circuit

37. Adherence to CPAP Therapy
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.
Self-reports often over estimate actual CPAP use.

39. Reasons for non-adherence to CPAP
1-Perception of lack of benefit: Patient education 2-Discomfort with its use (including mask): Mask refitting (nasal masks, nasal pillows, full-face masks, ororal masks) 3-Noise from the device Use of ear plugs or noise-attenuating devices 4-Air leaks from the mask or mouth: Mask refitting for mask leaks , Use of chin strap or full face mask for mouth leaks 5-Airway humidification , Treatment of nasal congestion 6-Difficulty with exhaling against high expiratory pressures Trial of CPAP with C-flex technology or bilevel positive airway pressure (BPAP)

40. Reasons for non-adherence to CPAP
7-Excessively high pressures: Trial of automated CPAP or Adjunctive therapy with sleep position treatment or oral devices. 8-Frequent nocturnal awakenings: Brief trial of (eszopiclone)during the initial CPAP use 9-Claustrophobia:Mask refitting (eg, nasal pillows or oral masks), desensitization of CPAP 10-Nasal problems: Dryness:-Airway humidification ,Use of nasal lubricants.Sneezing , Congestion , Rhinorrhea :- decongestants, anticholinergic agents, or corticosteroids , or antihistamine agents. Epistaxis:- Nasal surgery (in patients with nasal anatomic abnormalities) 11-Gastric distention due to aerophagia Bi- level PAP therapy

41. Beneficial effects of CPAP in OSA
Improvement in sleep quality
Elimination of snoring
Normalization in apneahypopnea index (AHI)
Increase in arterial oxygen saturation (SaO2)
Decrease in sleepiness (subjective and objective)
Enhancement of mood and neuro-cognitive function.
Improvement in quality of life

42. Beneficial effects of CPAP in OSA
Hypertension Improvement in blood pressure and heart rate profiles in patients with hypertension
Congestive heart failure Improvement in cardiac function in patients with OSA
Health care utilization Reduction in physician claims and hospital stay
Mortality Reversal of the increase in mortality associated with sleep apnea

43. Thank You & Pleasant DREAMS!