FLYING WITH CPAPDerek Figurski - Laboratory Manager Acknowledge Ms Leigh Seccombe from Concord Repatriation Hospital NSW

The scope of air travel942 ft or 290 m

Torino, Italy

A risky intersection?

Every day, over 16 000 Australians travel overseas and there are 120000 domestic passenger movements1

Estimated that up to 5% of middle age men & women in the general population have Obstructive Sleep Apnoea (OSA)2

Guidelines have been published to assist physicians and patients with lung disease and air travel3&4

How has commercial airlines adopted these guidelines, in particular with CPAP usage?

Airports Council International. World Traffic Report 2007

The aircraft environment 5315 ft or 1620 m

Zermatt, Switzerland

Modern aircraft Cruise altitude ~ 28 – 41 000ft (8500 – 12 500m) above

sea level Long haul flights up to 20 hours (A380 and Boeing 747

Dreamliner) Cabin air pressure falls as an aircraft ascends to cruising

altitudes

Cabin Environment Cocktail Pressurised with compressed ambient air taken from the

intakes of the jet engines (superheated) A small risk of contamination with fumes from engine

lubricants Add some recirculated air (filtered) without which cabin

humidity would be intolerably low Minimal risk of microbial contamination from new cabin

air

http://www.boeing.com/commercial/cabinair

Federal aircraft regulations Balance of passenger safety/comfort vs. operating costs Federal Aviation Administration (FAA) regulations*

Lowest cabin pressure = 76 kPa This is equivalent to 2400m (8000 ft) above sea level, This creates two issues:

First, gas within a closed cavity, such as the middle ear, sinuses, a poorly communicating bulla or a pneumothorax, will expand

Second, the falling pressure causes an equivalent fall in inspired oxygen levels

This degree of low oxygen levels is well tolerated and is not associated with any adverse effects

*Code of Federal Regulations Title 14, part 25.841 Washington

The two issues…… Relationship between altitude and pressure Relationship between altitude and trapped air Atmosphere oxygen levels at sea level and at altitude Oxygen levels in the blood at sea level and at altitude

25% of sea level pressure

The cabin environment What is the oxygen level?

The cabin environment % of oxygen in room air at sea level

(fraction of inspired oxygen – FIO2)

% of oxygen at 2400 m

= 21%

= 15%

Mt Kosciusko7310 ft or 2229 m

Are all flights the same?

7710 ft or 2350 m

Macchu Picchu Peru

Typical long-haul flight

Cabin altitudes are always below 2400 m, average of 1830 m5

Aircraft may not reach higher cruise altitudes for many hours due to the need for the flight to achieve appropriate altitude

Lowest oxygen levels at the end of a long flight

“Typical” Long-haul B747*

Sydney to Los Angeles

17%O2

Typical short-haul flight

Ascent and descent to cruise altitude may both take 20 minutes

Period at cruise altitude is quite short – may be only 40 minutes

Cabin altitude may get close to 2400 m but the period of risk is quite short

“Typical” short-haul A320*

Brisbane to Melbourne 15%O2

The effect on our oxygen levels

9086 ft or 2770 m

Telluride,Colorado

The normal response The physiological hazard

Low oxygen Low humidity (10-15%) Low activity

Altitude(ft)

FIO2 (%)

PB (mmHg)

PIO2(mmHg)

FIO2 %(sea level)

PaO2(mmHg)

SpO2(%)

0Sea Level

21 760 159 21 >80 >95

8000Max

Cabin

21 565 108 15.1 ≈ 60-70

>90

The normal response The physiological hazard

Low oxygen Low humidity (10-15%) Low activity

Altitude(ft)

FIO2 (%)

PB (mmHg)

PIO2(mmHg)

FIO2 %(sea level)

PaO2(mmHg)

SpO2(%)

0Sea Level

21 760 159 21 >80 >95

8000Max

Cabin

21 565 108 15.1 ≈ 60-70

>90

The OSA response to altitude

One of the hallmarks of severe OSA is repetitive oxygen desaturation (represented by SpO2)

Long haul flights may increase the risk of low SpO2, perhaps reflecting a gradual fall in cabin oxygen pressure.

Historically outcome data at altitude for this group of patients are limited and conflicting in nature

OSA patients with significantly low SpO2 at sea level would be expected to have more profound drop in SpO2 during apnoeic periods at high altitude, but there are no data on this issue

But if we look at patients with OSA performing the High Altitude Simulation Test (HAST)……..

OSA O2 Response Recent study5 investigated the degree of low oxygen levels

in untreated OSA (n = 15) vs. treated OSA (n = 14) performing a HAST (FIO2 = 15.1%)

Positive test for in flight supplemental oxygen is a PaO2 fall below 50mmHg (<6.6 kPa) or the SpO2 falls below 85%3

HAST the Flight Simulator

Actual cabin altitude and in-flight SpO2 on a study subject6 HAST SpO2 range (15 to 20 min) presented on the y2-axis

Results5

Results indicated that both groups had significant drop in SpO2 on the HAST with reported side effects (headache & light-headedness)

4/15 untreated OSA group had a positive test None of the treated OSA had a positive test Treated OSA showed a pattern of less severity in oxygen

desaturation

Untreated OSA (AHI ≥ 10/h) Treated OSA CPAP (AHI ≤ 10/h) for 6 weeks (≥ 4hr/night usage)

In summary A lower oxygen environment is present on aircraft than at

sea level, but there are minimal adverse effects Different aircraft types have varying cabin pressures, but

airlines need to adhere to regulations stipulated by government bodies

The affects of long haul flights on OSA patients is unknown Limited evidence suggests OSA can be an additional risk

for developing significant in flight hypoxaemia (low SpO2) similar to COPD & ILD

Further research is needed to assess the physiological responses of OSA at altitude for prolong periods

Limited evidence to date shows there is possible benefit to using CPAP (6 weeks) prior to exposure at altitude

Patients with obstructive or central sleep apnoea at sea level should travel to high altitude with their CPAP equipment

CPAP with Air Travel

9222 ft or 2812 m

Quito, Ecuador

Preparation prior to flight A doctor’s letter is required outlining the diagnosis and

necessary equipment. It should state that the continuous positive airway pressure (CPAP) machine should travel in the cabin as extra hand luggage (some airlines treat this as excess luggage)

A fact sheet for passengers to show airport security personnel in the USA is available from the American Sleep Apnea Association (www.sleepapnea.org)

Policies vary on the use of CPAP while flying and passengers need to contact the airline directly

Recent survery7 of 53 airlines in January 2008 servicing Australia & New Zealand reported:

28 (53%) permitted the use of CPAP machines during flight

9 (17%) did not permit the use of CPAP 16 (30%) were unable to ascertain their policies

Inconsistent Policy……

23 (82%) required a standard form to be completed

Survey was completed by 1 representative of the airline

Example Clearance Form

http://www.qantas.com.au

Also worth considering…. All 28 airlines required to bring their own CPAP machine

and dry cell batteries Not all plug-in are available on all airplanes in the fleet (6

airlines) Dry cell batteries should meet manufacturer's specification

and packed according to airline’s recommendation Supply of batteries adequate for 1.5 times the flight

duration Inconsistent information on current and voltage

requirements with only 4 airlines able to provide information on adaptors – Qantas, British Airways, Cathay Pacific & South African Airlines Air New Zealand only allows a US plug and no adaptor

Notification to airlines if passenger will be using CPAP during flight ranged from 2 days (46%) with a further 25% requiring 7 – 14 days

Remember to enjoy your flight!

CPAP Pitfalls in Flight

Mauna Lau,Hawaii

3059 m

Just a few…..

AC power is not usually available on board and passengers should use dry cell batteries; dry cell battery-powered CPAP can be used throughout except during take-off and landing

Power supplies are not available on all flights, sockets may not be available at every seat and, even if available, not all airlines allow them to be used for such equipment

Airlines do not always provide an appropriate adaptor and older machines may not be compatible with the power supply

Some CPAP machines can be powered from a direct current while others require an inverter

Dry batteries are heavy and will only power a CPAP machine for a limited time

Not enough pressure Captain! CPAP machines used in-flight should be capable of

performing adequately in the low pressure cabin environment

As noted above, if the equipment does not have pressure compensating features, a higher level of pressure will be necessary during the stay at simulated high altitude (cabin environment)

Calculations based on the collective fan laws and measurements made in a hypobaric chamber have shown that a fixed-pressure CPAP machine without pressure compensation set to deliver a pressure of 12 cm H2O at sea level may deliver only 9 cm H2O at 8000 ft 3

Machines with pressure sensors can deliver accurate pressures across a range of pressure/altitude combinations

General Advice

12002 ft or 3659 m

Lhasa, Tibet

CPAP usage Alcohol and sedatives should be avoided before and during

travel Possible further exacerbation of jetlag symptoms with no

usage Patients may wish to drive or work soon after overnight

flights; evidence suggests that withdrawing CPAP for just 1 day may cause sleepiness8

Arrange medical insurance Choose a machine approved by the FAA Provide the airline information about the physical size, make

and model of your machine when applying Check in early… Always review airline websites for up to date information

Air travel recommendations for Europe: www.european-lung-foundation.org

If unsure of advice given, seek an alternative within the airline

Concluding Remarks

13310 ft or 4058 m

La Paz, Bolivia

Conclusion

Your oxygen levels will be lower in-flight If you remember that risk of adverse events is minimal with

flight You may experience even lower oxygen levels while asleep

due to your sleep apnoea and CPAP is recommended You need to talk with your physician about the risk of not

using CPAP on long haul flights In addition seek advice if you are staying at your holiday

destination if at altitude for a long period of time Plan well in advance and check airline websites for up to date

information on the guidelines for CPAP usage Know your CPAP machine and seek advice from

manufacturers or local supplier Enjoy travelling and additional stopovers have benefits!

Questions

Hopefully airlines follow their own guidelines!

References1. Seccombe LM & Peters MJ, Patient with Lung Disease –

Fit to Fly, Australian Family Physician, Vol. 39, No. 3, MARCH 2010

2. Young T et al, Epidemiology of OSA, Am J Respir Crit Care Med, Vol 165. pp 1217–1239, 2002

3. Coker RK et al, Managing passengers with stable respiratory disease planning air travel: British Thoracic Society recommendations, Thorax, Vol. 66: i1ei30 2011

4. Aerospace Medical Association. Medical guidelines for air travel, 2nd edn. Aviat Space Environ Med 2003;74(Suppl 5): A1e19 http://www.asma.org/

5. Ali, M et al, Hypoxic challenge assessment in individuals with OSA, Sleep Medicine, Vol. 12, pp158–162 2011

6. Kelly, PT et al, Air Travel Hypoxemia vs the Hypoxia Inhalation Test in Passengers With COPD, Chest Vol. 133 / 4 / APRIL, 2008

7. Walker, J et al, Airline policies for passengers with OSA who require in-flight CPAP, Respirology, Vol. 15, pp 556 – 561 2010