1. CPAP and Humidification Therapy
Peggy Powers, RRT
Clinical Education
Fisher and Paykel Healthcare

2. Conflict of Interest Disclosure(s)
I do not have any potential conflicts of interest to disclose

3. MY CPAP GAVE ME A COLD!
Image: a person with a red nose followed by a person blowing their nose with a very loud sound!
Peggy says: Through the years we have often heard from patients that their CPAP gave them a cold, allergies or a sinus infection.
As a clinician when we first began to hear this we thought “hmmm, this guy may need a psych eval…..”
Then over time we began to associate these symptoms to the physiological response of the nose and upper airway.

4. Up to 75% of patients receiving CPAP therapy suffer from nasal congestion and upper airway congestion.
Inhalation of cool dry air increases nasal congestion and causes inflammation, this accounts for the patient reporting “MY CPAP GAVE ME A COLD”
Unless heat and humidity are replenished to the mucosa nasal obstruction develops, lying supine reduces the ability of the nose to condition cold dry air

5. Claustrophobia
Receiving inadequate airflow
Mouth breathing
Unconscious removal of the CPAP mask at night
Due to vascular reactivity of the turbinate’s and nasal congestion, nasal resistance may increase and the patient may present with:
The first point of intervention with the above should point to a humidification assessment. This assessment should consider… next slide

6. Environment Dusty house Cluttered house Pet dander Cold House
Hot House

7. Demographics/Climate
Desert
Ocean
Altitude
Swamp
Jungle
Individual physiology, environement and climate all should be considered for the patient that is experiencing congestion, runny nose , pressure intolerance, mouth breathing, claustophobia and pulling the mask off in the middle of the night.

8. Background to Humidification

9. Background to Humidification
What is Humidity?
Humidity is the amount of water vapor in a gas
Describing humidity
Absolute Humidity
Relative Humidity
Key humidity concepts
Maximum Capacity
Dew point
In order to understand humidification and its delivery in CPAP therapy, it is important to be familiar with the basics.
Humidity is defined as the amount of water vapour present in gas. In the upper airway, moisture is added to inspired air as water vapor.
There are four main concepts of humidification. These are absolute humidity and relative humidity. You will often hear these referred to as AH and RH.
The key humidity concepts we will cover are moisture capacity and dewpoint. These terms are critical to understanding rainout, or condensation in CPAP tubing.

10. Absolute Humidity (AH)
15 mg/L Absolute Humidity
15 mg
30 mg/L Absolute Humidity 1L
Absolute humidity, often referred to as AH, is defined as the amount of water vapour per litre of gas. This is an absolute measurement and simply tells us how much moisture there is. The true units are milligrams of water vapour – seen on the slide as mg of water per litre, the water is usually dropped and it is simply referred to as milligrams per litre. Water vapour is the gaseous form of liquid water.
The picture on the left shows a bottle with 1 litre capacity that is half full with water vapour. If the bottle were to be weighed, it would weigh 15mg. Hence, the absolute humidity is 15mg/L which is a measure of the mass of water vapour per litre of gas.
Similarly, the bottle on the right which has the same capacity as the bottle on the left is completely filled with water vapour. It weighs 30mg and therefore, the absolute humidity is 30mg/L. Once again, this is a measure of the mass of water vapour in a bottle of 1 litre capacity.
30 mg
mgH2O/L is usually referred to as mg/L

11. Relative Humidity (RH)
30 mg
100% Relative Humidity
Relative Humidity, often referred to as RH, is used to describe the relative amount of water vapour that exists in a volume of air in regards to the capacity of air to hold the water vapour. This is always described as a percentage. Like all percentage measurements we can use the equation of content over capacity to get the percentage.
The figure once again is comprised of the same bottle with 1 litre capacity. The bottle on the left is completely filled with water vapour, therefore the relative humidity is 100%, it holds the maximum amount it can. Remember that, in absolute humidity, the amount of water vapour that exists in 1 litre of gas is measured. RH turns this into a percentage by dividing this by the maximum amount of water the gas can hold.
The bottle on the right is only half filled with water vapour, therefore the relative humidity is 50%. We can work this out by using our content over capacity equation. The content, or amount of water vapour is 15mg. We know that when the bottle if full it holds 30mg, therefore content over capacity is equal to 15 over 30 which is equal to 0.5. If you have forgotten grade three maths, like most of us, we always multiply our fraction by 100 to get a percentage. Therefore 0.5 x 100 = 50%
It is important to clearly differentiate between absolute humidity and relative humidity.
30 mg
30 mg
15 mg
% = content/capacity x 100

12. Maximum Capacity 30 mg/L 27 mg/L 24 mg/L 22 mg/L 19 mg/L 17 mg/L
The capacity or the amount of moisture that air can hold is dependent on temperature. This involves some pretty complicated physics, but involves how fast the particles move at certain temperatures..
The graph here shows the maximum amount of water vapour gas can hold at certain temperatures. We can see this increase as the temperature increases. We have showed you this temperature range because this is in the typical range for CPAP delivery. You can see that we can double the amount of moisture it is possible to deliver if we have a temperature of 30 degrees Celsius (86 Degrees Farenheit) as against 18 degrees Celsius (64 degrees Farenheit).
If the absolute humidity were to remain constant as the temperature increases, the relative humidity would drop. This is simply because of the ability of the air to hold more moisture which results in an increased capacity and therefore a decreased percentage.
18 ºC 20ºC ºC ºC ºC ºC ºC

13. Dew Point The temperature at which water vapor begins to condense
Cooling process
Here, the gas is fully saturated i.e. 100% Relative Humidity
Dewpoint is the temperature at which water vapour begins to condense. Here, the gas is fully saturated with 100% relative humidity.
An example of this would be the condensation we see on the mirrors inside the bathroom after the shower. The air in the room becomes warm from the shower and can hold a larger amount of water vapour. As this air hits the cooler surface of the mirror it now cannot hold as much water vapour. This excess water vapour will be lost as condensation – this is the water you see on the mirror.
So as we cool a gas we decrease its ability to hold water vapour. As we cool below a temperature where the gas is fully saturated with water vapour, we can no longer hold that much water vapour in the air. This excess water vapour cannot be held in the air – so it condenses to its liquid form and appears as liquid water. This is condensation.

14. AH, RH & Dew Point 15 °C 37 °C 40 °C 2% RH 22 °C 100% RH 86% RH
44 mg/L
37 °C
100% RH
44 mg/L
22 °C
100% RH
20 mg/L
15 °C
2% RH
0.3 mg/L
AH, RH & Dewpoint
Objective: To use a practical example to bring the terms together. To use this example to explain how a heated humidifier and heated circuit works.
Let’s work through how heating & cooling a gas changes the absolute humidity, relative humidity and dewpoint of a gas.
A container of dry medical gas is cold and virtually devoid of any moisture.
If we heat the gas to 37 °C and add humidity to achieve 100% relative humidity, the gas can hold 44 mg of absolute humidity per litre of gas. At this temperature, the gas is at its dewpoint (37 °C). This is what happens in a chamber.
If the gas is heated to 40 °C and no water vapour is added ― as would occur in a heated circuit ― the amount of water vapour stays the same. Its capacity to hold water vapour increases to 51 mg/L, therefore the relative humidity will reduce to 44/51 x 100 = 86%.
Cooling the gas back to 37 °C will increase the relative humidity back to 100%.
If the gas is cooled further the maximum capacity reduces and condensation will form. Approval

15. Humidification & the Upper Airway

16. Anatomy of the Airway Gross anatomy of the airway Three main regions:
Naso-pharynx
Oro-pharynx
Trachea
Gross anatomy of the airway
Three main regions:
Naso-pharynx
Oro-pharynx
Trachea
The respiratory tract begins at the mouth and nose. For our purposes there are three main areas, the naso-pharynx, oro-pharynx and the trachea. The trachea (or windpipe) divides into the right and left main bronchi, which enter the right and left lungs. These break up into smaller bronchi and bronchioles ending in small air sacs or alveoli, where gas exchange occurs.

17. Anatomy of the Nasal Passage
This is a closer look at the structures of the nasal passage

18. Isothermic Saturation
Inspiration
31 °C
Naso/Oropharynx
30 mg/L, 90% RH
36 °C
Trachea
42 mg/L, 100% RH
37 °C
Isothermic Saturation
Boundary
44 mg/L, 100% RH
22 °C
Room Air
7 mg/L, 35% RH
The air we breath in is cool and dry. In normal conditions, the air will reach body temperature and be saturated with water vapour by the time it reaches the lungs. The temperature and humidity of inspired air increases as it passes through the airways lined with a moist mucosa at body temperature.

19. Normal Airway Inspiration
Cilia cell
Cilia
Mucus
Blood vessel
This diagram illustrates the addition of heat and moisture to the air during inspiration. Water from the blood is transferred to the air via a mucus layer on the airway.

20. Expiration
75% of the heat and moisture is lost to the environment1,2
The majority of the recovery (25%) is in the naso- and oro-pharynx
33 °C
30 mg/L, 85% RH
During expiration 25% of the water and heat gained during inspiration is returned to the mucus layer. The warm exhaled air cools down as it passes the cooler mucosa. This causes the gas to fall below dewpoint, resulting in condensation on the mucosa. The remaining 75% is lost to the outside environment as we breathe out. This is why it feels hot and wet if we place our hand in front of our mouth as we breathe out.
1Ingelstedt, 1956; 2Cole, 1954

21. Normal Airway - Expiration
Cilia cell
Cilia
Mucus
This diagram illustrates how some heat and moisture is returned to the airway during expiration.

22. Nasal Symptoms The airway is a natural heated humidifier
A constant flow of air delivered via CPAP can dry the nasal mucosa
Excessive drying of the nasal mucosa increases nasal resistance, thereby increasing nasal discomfort
Production of mucus is also increased to help humidify the additional air flow
These factors can induce symptoms such as nasal congestion
As discussed above, every time we breathe in heat and moisture is added to the air. Therefore our airway can be seen as a natural form of a heated humidifier.
CPAP delivers a constant flow of air, therefore sometimes our body can not keep up with the increased demand. Drying of the nasal mucosa can produce nasal symptoms, such as nasal congestion.

23. Nasal Congestion
Nasal congestion is a narrowing/blockage of the nasal passages
It is usually due to membranes lining the nose becoming swollen from inflamed blood vessels.
Nasal congestion is also known as nasal obstruction, blocked nose, runny nose, or stuffy nose.

24. Nasal Symptoms
Nasal symptoms can be alleviated by the use of a humidifier with your CPAP
When the flow of air is already humidified this reduces the demand on the bodies natural humidification system

25. Available Humidification Technologies

26. Humidification Delivery Modes
No humidity
Cold pass-over
Conventional heated humidification
Heated breathing tube
We will look at four main types of humidification delivery that is used and these will be explored further in the slides following.
No humidity – as the name suggests, no humidification is delivered to the paitent.
Cold pass-over – passing air over cold water
Conventional heated humidification – heating the water in the chamber to a controlled temperature in order to deliver humidified air
Heated breathing tube – using its own controlled environment by not allowing ambient temperature to affect the level of humidity that is delivered

27. CPAP treatment where no humidity is delivered to patients
No Humidification
CPAP treatment where no humidity is delivered to patients
Effectively delivers ambient air

28. Effects of No Humidification
Nasal symptoms - dryness of nasal mucosa & nasal congestion
Mouth leak
Therapy abandonment

29. Cold Pass-Over Humidification
What is cold pass-over humidification?
Passing of cold air over water
An interim treatment for patients who complain of nasal symptoms after initiation of CPAP
Cold pass-over is simply filling the chamber up with cold water and passing air over while delivering CPAP therapy to patients. It is a treatment that is usually used an interim for those patients who complain of nasal symptoms after initiation of CPAP treatment. These patients are generally exposed to cold dry air from their CPAP without any humidification which causes nasal congestion and dryness of the nasal mucosa.

30. Effects of Cold Pass-over
No clinical evidence available to support the use of cold pass-over
Increase in nasal resistance on dry CPAP (no humidification) are unchanged with cold pass-over
Mouth leak
Therapy abandonment

31. Conventional Heated Humidification
What is conventional heated humidification?
Heating the water filled chamber using a heater plate
Air passing over the heated water adds moisture and humidifies the delivered air
Turbulence induced in the chamber helps pick up humidity
Conventional humidification is the delivery of humidified air to the patient by heating the water filled chamber to a controlled temperature. The air that passes over the water in the chamber is turbulent and this turbulence helps pick up moisture. Therefore, the air that is delivered to the patient is more moisture laden and humidified.

32. Benefits of Conventional Heated Humidification
Alleviates reported nasal discomfort
Lowers therapy abandonment
Improves patient compliance
Reduces the incidence of mouth leak
The proven benefits of conventional heated humidification are listed here. When we refer to conventional heated humidification we mean a heated humidifier with a standard, non-heated breathing tube. With conventional heated humidification we know we can alleviate nasal discomfort, lower abandonment of therapy, improve compliance and reduce mouth leak. We will discuss these in further detail, and discuss the evidence for these claims in phase two.

33. Limitations of Conventional Heated Humidification
Ambient air temperature
Condensation
Disruptive noise leading to fluctuating mask pressure
Whilst conventional humidification is used in around 80% of CPAP patients, it does have some limitations. The main problem is that the air becomes warm and picks up moisture at the chamber, as the air travels down the tube it cools, as the ambient air is colder than the air in the tube. As this happens, the air drops below its dewpoint, as we learned earlier in the presentation. This is when condensation occurs. This condensation can cause a disruptive gurgling noise and lead to pressure fluctuations at the mask.

34. TUBE COOLING = CONDENSATION BUILD UP = PATIENT DISRUPTION
Condensation – Conventional Humidification
30 oC 29 mg/L
20 oC
17 mg/L
TUBE COOLING = CONDENSATION BUILD UP = PATIENT DISRUPTION
Condensation in the breathing tube is a major problem experienced in delivering conventional humidification.
In this illustration, the humidifier supplied with the CPAP delivers absolute humidity at 29 mg/L at 30°C initially. However, as ambient temperature drops to 20°C, the humidity delivered is also subsequently reduced to 17 mg/L.
As a result, the humidity setting that was ideal at the beginning of the night is no longer effective as ambient temperature drops further along into the night.
This illustration depicts condensation in a breathing tube. As the temperature drops across the tube, the cooling effect results in the initially moisture laden air to condensate and accumulate as water drops. Over a period of time, the accumulation of water increases which results in a gurgling noise and added resistance to the CPAP circuit.

35. Condensation Bacon et al, 2000
Let us now examine the effect of condensation on mask pressure.
In an ideal scenario where condensation is non existent, the mask pressure is relatively stable. This is graphically shown by the line graph on the left.
The right hand side of the graph shows what happens when there is 10 mL of condensate into the tube. Mask pressure now fluctuates severely as a result of the condensation. This can be explained by the fact that, water accumulation in the tube acts as resistance to the CPAP pressure delivered. The patient will also hear a disruptive gurgling noise as the condensation moves around in the tube.
Bacon JP, Farney RJ, Jensen RL et al. Nasal continuous positive airway pressure devices do not maintain the set pressure dynamically when tested under simulated clinical conditions. Chest 2000; 118(5):
Bacon et al, 2000

36. Heated Breathing Tube (HBT)
What is the idea behind the heated breathing tube?
Copper wire coiled inside breathing tube
Discounts the effects of changing ambient temperature
Operates in its own controlled environment
While conventional humidification is more comfortable for patients in comparison to cold pass-over, it is not without its own fair share of limitations. We have seen the effect condensation in the tubing has on delivered pressure and this arises due to changing ambient temperatures through the night.
The heated breathing tube (HBT) is a copper wire coiled along the length of the breathing tube which maintains a constant temperature gradient. By doing so, the effects of changing ambient temperature is eliminated and condensation is avoided making the HBT operate within its own controlled environment.

37. Conventional vs HBT 30mg/L 18 mg/L 30mg/L 30mg/L Conventional HBT
Timeline hrs
Conventional Humidification
Conventional
30mg/L
18 mg/L
TUBE COOLING - CONDENSATE FORMS
Timeline hrs
Heated Breathing Tube Humidification
HBT
30mg/L
30mg/L
By adding a heated breathing tube to a CPAP we can overcome the ambient temperature and condensation limitations of conventional humidifiers.
As established before, with conventional humidification the amount of humidity delivered is reduced at the mask level as the temperature along the tube begins to cool. Hence, the air is no longer able to carry the moisture it initially contained and it is lost as condensation.
The figure below depicts how the HBT creates its own operating environment. Here we can see that the initially delivered level of humidity of 30 mg/L is not reduced at the mask level even if ambient temperature drops.
WARM TUBE: HEAT LOSS + HEAT GAIN = CONSTANT HEAT

38. HBT Clinically Proven for A Better Nights Sleep
ThermoSmart™ is Fisher and Paykel’s patented heated breathing tube technology.

39. ThermoSmart™ THE ORIGINAL HEATED BREATHING TUBE
FPH 40 years of experience in humidification technology
5 years of global ThermoSmart™ market experience
Dedicated research program
THE ORIGINAL HEATED BREATHING TUBE
With over 30 years’ experience, introducing leading-edge humidification products and technologies to the ICU, as well as being the first to introduce a fully integrated CPAP/humidifier to the OSA market, Fisher & Paykel Healthcare is recognized as the industry specialist in humidification.
ThermoSmart™ was the first heated breathing tube technology introduce to the CPAP market and is designed to increase the level of humidity available to CPAP patients to a level that matches or mimics the upper airway.

40. HBT No other HBT has the same advanced technology
ThermoSmart™ combines several key technologies to deliver high (physiological) levels of humidification:
A Heated Breathing Tube retains heat along the tube ensuring the intended level of humidity reaches the mask and patient, as well as working to prevent condensation
A temperature sensor monitors and responds to room temperature to prevent condensation
A flow sensor identifies mouth leak and increases humidity to compensate
A high-capacity power supply generates humidity on demand
A large-capacity water chamber ensures lasting humidity delivery
No other HBT has the same advanced technology
WHAT IS THERMOSMARTTM?
ThermoSmart™ combines several key technologies to deliver high (physiological) levels of humidification:
A Heated Breathing Tube that retains heat along the tube ensuring the intended level of humidity reaches the mask and patient, as well as working to prevent condensation
A temperature sensor monitors and responds to room temperature to prevent condensation
A flow sensor identifies mouth leak and increases humidity to compensate
A high-capacity power supply generates humidity on demand
A large-capacity water chamber ensures lasting humidity delivery

41. Sensors & algorithms in place of RH and EOH sensors
The sophisticated algorithm used means the results achieved by an end of hose RH sensor can be mimicked
Different levels of RH are built into each ThermoSmart™ Boost setting
F&P consistently delivers higher levels than both the SystemOne and S9 systems

42. The Best Humidification System
After one hour stabilization period. Room conditions 50% RH and 23 deg C (74F)
After one hour stabilization period. Room conditions 50% RH and 23 ºC (74 ºF)

43. Proven Clinical Research
Clinical Studies support the effectiveness of ThermoSmart™:
Nilius: improves sleep quality and total sleep time
Almasri: provides a more comfortable CPAP experience
Virag: eliminates condensation while delivering higher levels of absolute humidity
Massengill: lowers nasal airway resistance for 10% lower titration pressure
There is now a compelling body of clinical evidence to support the effectiveness of ThermoSmart™ in providing greater levels of humidity and comfort to the patient. The four key studies to discuss with customers are listed in this slide.
We will cover each of these in detail in Phase three.

44. HBT START WITH THERMOSMART™
The findings from these studies reinforce the idea that the solution to many of the commonly reported side effects associated with the initiation of CPAP therapy might be right under your nose. This table lists frequently reported side effects, which occur during the initiation of therapy. This is the most crucial time to identify and overcome any CPAP-related side effects, as long-term adherence to CPAP is determined within the first few days and weeks of treatment.
ThermoSmart™ may proactively prevent both pressure and drying-related issues.
References: (NEED TO SORT OUT IMAGE – NINA HAS IT IN HAND)
3. Massengill, J.S. and K.L. Lewis, Effect of humidification on titration pressures in obstructive sleep apnea. Sleep, : p. A217.
4. Almasri, E. and L. Kline, The addition of heated wall tubing provides more humidity and comfort than standard heated humidifier CPAP units. Sleep, : p. A190.
5. Nilius, G., et al., Impact of a controlled heated breathing tube humidifier on sleep quality during CPAP therapy in a cool sleeping environment. European Respiratory Journal, (4): p
6. Powell, Can heated humidity with a heated breathing tube comparably improve CPAP usage and nasal symptom complaints as an intranasal steroid? Sleep, : p. A159. and Powell, A secondary analysis comparing a heated CPAP breathing tube to a nasal steroid in poorly compliant patients: quality of life and functioning Sleep, : p. A164.
7. Virag (etc)

45. The addition of a heated breathing circuit to a delivery system:
Clinical Summary
Ensures stable gas temperatures
Allows for higher humidity levels to be delivered
Increased patient comfort and therefore compliance
Eliminates condensation
Ensures mask pressure stability
No sleep cycle disruptions from tubing noise
The addition of a heated breathing circuit to a delivery system:

46. End