FLYING WITH CPAPDerek Figurski - Laboratory ManagerAcknowledge Ms Leigh Seccombe from Concord Repatriation Hospital NSW
The scope of air travel 942 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, inAirports Council International. World Traffic Report 2007 particular with CPAP usage?
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 Atmosphere oxygen levels at and pressure sea level and at altitude Relationship between altitude Oxygen levels in the blood at and trapped air 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 = 21% (fraction of inspired oxygen – FIO2) % of oxygen at 2400 m = 15% Mt Kosciusko 7310 ft or 2229 m
Are all flights the same? 7710 ft or 2350 m Macchu Picchu Peru
Typical long-haul flight“Typical” Long-haulB747* 17%O2Sydney to Los Angeles 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 short-haul flight“Typical” short-haul A320*Brisbane to Melbourne 15%O2 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
The effect on our oxygen levels 9086 ft or 2770 m Telluride, Colorado
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 SimulatorActual cabin altitude and in-flight SpO2 on a study subject6HAST 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……Survey was 23 (82%)completed by 1 required arepresentative standardof the airline form to be completed
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 manufacturers 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 20102. Young T et al, Epidemiology of OSA, Am J Respir Crit Care Med, Vol 165. pp 1217–1239, 20023. Coker RK et al, Managing passengers with stable respiratory disease planning air travel: British Thoracic Society recommendations, Thorax, Vol. 66: i1ei30 20114. 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 20116. Kelly, PT et al, Air Travel Hypoxemia vs the Hypoxia Inhalation Test in Passengers With COPD, Chest Vol. 133 / 4 / APRIL, 20087. Walker, J et al, Airline policies for passengers with OSA who require in- flight CPAP, Respirology, Vol. 15, pp 556 – 561 2010