SUBJECT REVIEW
Air Travel of Patients With Abdominal Aortic Aneurysm: Urgent Air Medical Evacuation and Nonurgent Commercial Air Repatriation Andrew Barros, BS,1 Faith Haffner, RN,2 François-Xavier Duchateau, MD,3 J. Stephen Huff, MD,1,2,4,5 Laurent Verner, MD,3 Robert E. O’Connor, MD,1,2,5 and William J. Brady, MD1,2,5,6
Abstract Abdominal aortic aneurysm (AAA) presents across a spectrum of severity. Although some resources suggest a theoretic risk for rupture related to air travel, this claim remains unproven. In fact, there are little data from which to make evidence-based recommendations. Air medical evacuation of a patient with either an AAA at risk of imminent rupture or status post recent rupture can be performed, assuming that local surgical care is not available and that transfer is taking the patient to a higher level of medical intervention. Furthermore, medical opinion suggests that patients with asymptomatic and/or surgically corrected AAA can safely travel by commercial aircraft for nonurgent reasons, assuming that other issues including postoperative needs are appropriately addressed. In this discussion, answers to the following issues are sought: flight safety for urgent evacuation and nonurgent repatriation scenarios, waiting time to fly nonurgently after AAA diagnosis, and the need for medical accompaniment.
Introduction Air travelers over the age of 65 years with abdominal aortic aneurysm (AAA) are likely not uncommon. In the 2013 United States Department of Transportation’s omnibus survey, approximately 30% of adults 65 years or older reported at
1. Department of Emergency Medicine, University of Virginia School of Medicine, Charlottesville, VA 2. Allianz Global Assistance Canada, Kitchener, Ontario, Canada 3. Allianz Global Assistance France, Paris, France 4. Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA 5. Allianz Global Assistance USA, Richmond, VA 6. Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA Address for correspondence: William J. Brady, MD, Department of Emergency Medicine, PO Box 800699, University of Virginia Medical Center, Charlottesville, VA 2290, [email protected] 1067-991X/$36.00 Copyright 2014 by Air Medical Journal Associates http://dx.doi.org/:10.1016/j.amj.2014.02.006 May-June 2014
least 1 airplane trip in the previous 12 months.1 A large multicenter trial of ultrasound screening for abdominal aortic aneurysm noted a prevalence of 4.9% for AAA in men older than 65 years.2 If one combines this AAA prevalence with the 643 million passengers who embarked on a flight originating in the United States in 2013, it is likely that millions of passengers with an AAA flew during the time period. A smaller subset of this traveling group will seek treatment for their AAA while traveling. Thus, the travel medicine physician will be called on to determine fitness to fly in these patients. Although there are professional society guidelines about the diagnosis and management of AAA,3 guidance is limited and quite unclear regarding the safety of urgent air medical evacuation and nonurgent commercial air travel for the patient with an AAA. The following questions were explored: (1) Is it safe to evacuate (ie, emergently transfer via air ambulance) patients with a symptomatic AAA by air? (2) Is it safe to repatriate (ie, nonurgently allow to return to home region via commercial air) patients with asymptomatic, symptomatic, or repaired AAA by air? (3) If nonurgent travel is determined to be safe, what time interval is required to pass from diagnosis and/or management of the AAA before allowing flight? and (4) Is nurse accompaniment or other medical assistance needed during flight? In the review of this topic, no evidence-based recommendations or guidelines were noted. It is suggested that research in this topic is needed to more completely advise the traveling patient with AAA. Medline and PubMed databases were used with the following search terms: abdominal aortic aneurysm, AAA, aneurysm, travel, commercial air, and aviation. In addition, Google and Ask searches were performed using these terms. This article is written by physicians practicing emergency medicine in the United States and France; in addition to active emergency medicine practice, these physicians are also medical directors of a worldwide travel insurance company providing real-time medical following of patients with active medical issues during their travel, including AAA. This article reviews the existing recommendations with conclusions based on both these limited data and rationale conjecture.
Pathophysiology and Physics of AAA The pathogenesis of AAA is a multifactorial process leading to alteration in the aortic vascular wall connective tissue. In 109
general, the loss of elastin and replacement with collagen ultimately allows the aorta to enlarge, producing aneurysmal dilation. The abnormally dilated wall is subject to continued stress, placing the AAA at risk for rupture.4 The magnitude of risk is dependent on a range of factors, including size, rate of growth, shape, and active symptoms (ie, pain).3 Once an AAA has developed, sudden increases in blood pressure and ongoing hypertension are accepted as risk factors for rupture; furthermore, lowered atmospheric pressure may increase rupture rates. Commercial aircraft are not pressurized to ground-level pressure, but for economic and mechanical reasons, the cabin pressure varies between ground-level pressure and a maximum equivalent cabin altitude of 8,000 ft.5 Thus, there is a theoretic concern of an increased chance of rupture because of air travel at altitude in pressurized cabins of aircraft. In general, it must be recalled that lowered atmospheric pressure equals increased altitude. A growing body of literature has reported on the association of low atmospheric pressure and the risk of ruptured AAA. One UK study reviewed 5 years of data, correlating the rate of AAA rupture and atmospheric pressure; the investigators described 50 cases of RAAA, noting an associated lower mean monthly pressure and a higher occurrence of rupture.6 Other studies have shown similar associations; 1 Northern Ireland study noted a lower recent atmospheric pressure with AAA rupture,7 1 in Germany noted atmospheric pressure variations and AAA rupture,8 and 1 in Turkey reported seasonal atmospheric pressure variation associated with rupture.9 Conversely, several smaller series have failed to show an association between atmospheric pressure and rupture.10-13 Yet, these studies are all constructed differently, making a consensus statement difficult based on this literature. Applying this literature base to the issue of AAA rupture risk and air travel is challenging. The extrapolation of these atmospheric pressure variations to the AAA patient and air travel is difficult at best. In fact, the medical literature does not report cases of AAA that ruptured directly as a result of air travel. At most, there is an unproven, suggested association between air travel and AAA rupture; there appears to be a small, but measurable, association between lower atmospheric pressure and AAA rupture. There is some heterogeneity in the methods used to quantify lower pressure (ie, 4-day variation, lowest pressure in the preceding month, and average pressure in the preceding month), making it difficult to draw specific conclusions. The medical literature does not report cases of AAA that ruptured as a result of air travel. However, the medical literature does note 3 reported cases1416 of aortic dissection associated with air travel. Whether brief decreases in atmospheric pressure such as air travel affect AAA has yet to be shown.
Discussion of the Questions Is it safe to evacuate patients with a symptomatic AAA by air? Ruptured AAA has an extraordinarily poor prognosis with an estimated mortality rate of 88%.17 A systematic review by 110
Hoornweg et al18 of 60,822 patients noted an overall mortality rate for the surgical repair of ruptured AAAs of 48.5%. One center described their success in setting up direct to surgical suite transportation of unstable AAAs with leak by air transport.19 A retrospective series of suspected unstable AAAs transported from the field where 50% received surgical intervention showed 9% prehospital mortality.20 Faced with these statistics, there is little doubt that for the patient with a symptomatic or ruptured AAA, the benefits of surgical intervention outweigh the theoretic atmospheric pressure changes and the risk of air medical evacuation. Is it safe to repatriate patients with asymptomatic, symptomatic, or repaired AAA by air? And, the related question, if nonurgent travel is determined to be safe, what time interval is required to transpire from diagnosis and/or management of the AAA before allowing flight? There are extremely limited data about if, and when, it is safe for patients with asymptomatic AAAs to fly. The International Air Transport Association medical manual provides no specific guidelines on the need for medical clearance or safety of travel with an AAA. Although making no specific recommendation about flying after AAA surgical repair, the guidelines do require medical clearance to fly within 10 days of “cardiac surgery.” An Internet search using Google for “flying AND aortic aneurysm” revealed a small number of presurgical patient education pamphlets. These recommendations vary from “You should not fly anywhere for 6 weeks after your surgery”21 to “changes in cabin pressure during a flight may increase the risk of rupture of a large abdominal aortic aneurysm.”22 Although a different population, the UK Civil Aviation Authority allows for commercial pilots with an infrarenal AAA less than 5 cm to be licensed with the restriction that they always fly with a copilot.23 After surgical repair, pilots with an aneurysm of any size can be licensed with the same requirements. These guidelines provide no rationale for their recommendations. This risk is, at best, a theoretic concern that is not supported by scientific experimental data.22 Of course, the pressure changes during fixed wing air ambulance flight can be minimized by flying pressurized to sea level. Thus, medical “common sense” is the best guide for determining when a patient with AAA can safely fly in a nonurgent fashion on a commercial aircraft. The final question is is nurse accompaniment or other medical assistance needed during flight? There is no recommendation in the medical or flight literature commenting on the necessity of a medical attendant during flight. Furthermore, no data exist to support the need for a nurse or other medical accompaniment during a nonurgent, commercial flight, resulting solely from AAA. The presence of a medical attendant, whether an emergency medical service provider, nurse, or physician, on a commercial flight will likely not alter the outcome of a patient with an AAA that suddenly ruptures. Certainly, a medical escort can be provided for a postoperative patient who is debilitated or Air Medical Journal 33:3
deconditioned. Yet, the medical need in this example is not the AAA itself; in other words, medical accompaniment should be determined based on patient need and not simply the primary diagnosis.
Summary and Conclusions AAA presents across a spectrum of severity. Although some resources suggest a theoretic risk for rupture related to air travel, this claim remains unproven. In fact, there are little data from which to make evidence-based recommendations. Air medical evacuation of a patient with either an AAA at risk of imminent rupture or status post recent rupture can be performed, assuming that local surgical care is not available and that transfer is taking the patient to a higher level of medical intervention. Furthermore, medical opinion suggests that patients with asymptomatic and/or surgically corrected AAA can safely travel by commercial aircraft for nonurgent reasons, assuming that other issues including postoperative needs are appropriately addressed. The following are answers to our previous questions: 1. Is it safe to evacuate patients with a symptomatic AAA by air? Given the overwhelming mortality from unrepaired ruptured, leaking, or symptomatic AAAs, the benefits of rapid air medical transportation to definitive treatment are clear. In many cases, this transfer will occur by air ambulance; in this instance, the benefits of rapid transfer for definitive surgical care clearly outweigh the theoretic risks of an increased rupture rate caused by atmospheric changes related to air travel. 2. Is it safe to repatriate patients with asymptomatic, symptomatic, or repaired AAA by air? Again, the unproven risk of atmospheric pressure–related rupture must be balanced against the practical benefits of air travel. There is no literature (not even case reports) of air travel precipitating rupture in an asymptomatic AAA. Similarly, a surgically repaired AAA becomes an asymptomatic AAA. In the absence of another compelling reason (ie, surgical complication or other active comorbid issue) for delayed travel, these patients can likely travel safely via an escorted commercial airliner. 3. If nonurgent travel is determined to be safe, what time interval is required to transpire from the diagnosis and/or management of the AAA before allowing flight? The answer to this question is not found in the medical literature. Thus, medical “common sense” is the best guide for determining when the patient with AAA can safely fly in a nonurgent fashion on a commercial aircraft. 4. Is nurse accompaniment or other medical assistance needed during flight? Again, as mentioned previously, no scientifically based recommendation can be made in this instance. Medical judgment is best used in this consideration, realizing that the patient with a rupturing AAA likely will not have his or her outcome altered by a medical attendant. May-June 2014
References 1. Bureau of Transportation Statistics. Omnibus survey: household survey. Available at: http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/subject_areas/omnibus_sur veys/household_survey/2009/october/index.html. Accessed October 20, 2013. 2. Ashton HA, Buxton MJ, Day NE, et al. Multicentre Aneurysm Screening Study Group. The multicentre aneurysm screening study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised controlled trial. Lancet. 2002;360:1531-1539. 3. Chaikof EL, Brewster DC, Dalman RL, et al. SVS practice guidelines for the care of patients with an abdominal aortic aneurysm: executive summary. J Vasc Surg. 2009;50:880-896. 4. Wassef M, Baxter BT, Chisholm RL, et al. Pathogenesis of abdominal aortic aneurysms: a multidisciplinary research program supported by the national heart, lung, and blood institute. J Vasc Surg. 2001;34:730-738. 5. Aerospace Medical Association Medical Guidelines Task Force. Medical guidelines for airline travel, 2nd ed. Aviat Space Environ Med. 2003;74(suppl):A1-19. 6. Kordzadeh A, Askari A, Panayiotopoulos Y. Atmospheric pressure and infra-renal abdominal aortic aneurysm rupture: a single observational study and a comprehensive review of literature. Int J Surg. 2013;11:458-462. 7. Killeen SD, O'Sullivan MJ, Coffey JC, Redmond HP, Fulton GJ. Atmospheric pressure variations and abdominal aortic aneurysm rupture. Ir J Med Sci. 2008;177:217-220. 8. Schuld J, Kollmar O, Schuld S, Schommer K, Richter S. Impact of meteorological conditions on abdominal aortic aneurysm rupture: evaluation of an 18-year period and review of the literature. Vasc Endovascular Surg. 2013;47:524-531. 9. Rabus MB, Eren E, Erkanli K, Alp M, Yakut C. Does acute aortic dissection display seasonal variation? Heart Surg Forum. 2009;12:E238-240. 10. Kurtoglu M, Yanar H, Aksoy M, et al. Seasonality in the incidence of abdominal aortic aneurysm ruptures: a review of eight years. Ulus Travma Acil Cerrahi Derg. 2004;10:39-41. 11. Molacek J, Treska V, Kasik M, et al. Correlation between atmospheric pressure changes and abdominal aortic aneurysm rupture: results of a single-center study. Surg Today. 2013;43:1003-1037. 12. Repanos C, Chadha NK. Is there a relationship between weather conditions and aortic dissection? BMC Surg. 2005;15:21. 13. Verberkmoes NJ, Soliman Hamad MA, Ter Woorst JF, et al. Impact of temperature and atmospheric pressure on the incidence of major acute cardiovascular events. Neth Heart J. 2012;20:193-196. 14. Fozzato F, Prioli MA, Santini F, et al. Aortic intramural hematoma fissuration: atypical presentation in an aircraft pilot. G Ital Cardiol. 2010;11:162-164. 15. Ghosh AK, Lodge FM, Dubrey SW. Acute aortic dissection with a high D-dimer and pleuritic chest pain in an airline passenger. Clin Med. 2010;10:409-411. 16. Shaw KP, Ho BL, Lee WH, Fong JM. Rupture of dissecting aneurysm in a china airlines co-pilot. Forensic Sci Int. 1996;81:157-164. 17. Bengtsson H, Bergqvist D. Ruptured abdominal aortic aneurysm: a populationbased study. J Vasc Surg. 1993;18:74-80. 18. Hoornweg LL, Storm-Versloot MN, Ubbink DT, et al. Meta analysis on mortality of ruptured abdominal aortic aneurysms. Eur J Vasc Endovasc Surg. 2008;35:558-570. 19. Shewakramani S, Thomas SH, Harrison TH, Gates JD. Air transport of patients with unstable aortic aneurysms directly into operating rooms. Prehosp Emerg Care. 2007;11:337-342. 20. Mitchell AD, Tallon JM. Air medical transport of suspected aortic emergencies. Air Med J. 2002;21:34-37. 21. Royal Berkshire NHS Foundation Trust. Information for patients having an abdominal aortic aneurysm repair. Available at: http://www.royalberkshire.nhs.uk/pdf/ AAA.pdf. Accessed October 14, 2013. 22. Bedfordshire Vascular Unit NHS Foundation Trust. Abdominal aortic aneurysm: information for patients. Available at: http://www.rcsed.ac.uk/fellows/pvtisi/ Abdominal%20Aortic%20Aneurysm%20%20June%2012.pdf. Accessed October 14, 2013. 23. UK Civil Aviation Authority. Guidance for medical certification of aircrew: cardiovascular system 2012. Available at: http://www.caa.co.uk/default.aspx?catid⫽2499& pagetype⫽90&pageid⫽13796#Aneurysm. Accessed September 11, 2013.
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Air Travel of Patients With Abdominal Aortic Aneurysm: Urgent Air Medical Evacuation and Nonurgent Commercial Air Repatriation Andrew Barros, BS,1 Faith Haffner, RN,2 François-Xavier Duchateau, MD,3 J. Stephen Huff, MD,1,2,4,5 Laurent Verner, MD,3 Robert E. O’Connor, MD,1,2,5 and William J. Brady, MD1,2,5,6
Abstract Abdominal aortic aneurysm (AAA) presents across a spectrum of severity. Although some resources suggest a theoretic risk for rupture related to air travel, this claim remains unproven. In fact, there are little data from which to make evidence-based recommendations. Air medical evacuation of a patient with either an AAA at risk of imminent rupture or status post recent rupture can be performed, assuming that local surgical care is not available and that transfer is taking the patient to a higher level of medical intervention. Furthermore, medical opinion suggests that patients with asymptomatic and/or surgically corrected AAA can safely travel by commercial aircraft for nonurgent reasons, assuming that other issues including postoperative needs are appropriately addressed. In this discussion, answers to the following issues are sought: flight safety for urgent evacuation and nonurgent repatriation scenarios, waiting time to fly nonurgently after AAA diagnosis, and the need for medical accompaniment.
Introduction Air travelers over the age of 65 years with abdominal aortic aneurysm (AAA) are likely not uncommon. In the 2013 United States Department of Transportation’s omnibus survey, approximately 30% of adults 65 years or older reported at
1. Department of Emergency Medicine, University of Virginia School of Medicine, Charlottesville, VA 2. Allianz Global Assistance Canada, Kitchener, Ontario, Canada 3. Allianz Global Assistance France, Paris, France 4. Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA 5. Allianz Global Assistance USA, Richmond, VA 6. Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA Address for correspondence: William J. Brady, MD, Department of Emergency Medicine, PO Box 800699, University of Virginia Medical Center, Charlottesville, VA 2290, [email protected] 1067-991X/$36.00 Copyright 2014 by Air Medical Journal Associates http://dx.doi.org/:10.1016/j.amj.2014.02.006 May-June 2014
least 1 airplane trip in the previous 12 months.1 A large multicenter trial of ultrasound screening for abdominal aortic aneurysm noted a prevalence of 4.9% for AAA in men older than 65 years.2 If one combines this AAA prevalence with the 643 million passengers who embarked on a flight originating in the United States in 2013, it is likely that millions of passengers with an AAA flew during the time period. A smaller subset of this traveling group will seek treatment for their AAA while traveling. Thus, the travel medicine physician will be called on to determine fitness to fly in these patients. Although there are professional society guidelines about the diagnosis and management of AAA,3 guidance is limited and quite unclear regarding the safety of urgent air medical evacuation and nonurgent commercial air travel for the patient with an AAA. The following questions were explored: (1) Is it safe to evacuate (ie, emergently transfer via air ambulance) patients with a symptomatic AAA by air? (2) Is it safe to repatriate (ie, nonurgently allow to return to home region via commercial air) patients with asymptomatic, symptomatic, or repaired AAA by air? (3) If nonurgent travel is determined to be safe, what time interval is required to pass from diagnosis and/or management of the AAA before allowing flight? and (4) Is nurse accompaniment or other medical assistance needed during flight? In the review of this topic, no evidence-based recommendations or guidelines were noted. It is suggested that research in this topic is needed to more completely advise the traveling patient with AAA. Medline and PubMed databases were used with the following search terms: abdominal aortic aneurysm, AAA, aneurysm, travel, commercial air, and aviation. In addition, Google and Ask searches were performed using these terms. This article is written by physicians practicing emergency medicine in the United States and France; in addition to active emergency medicine practice, these physicians are also medical directors of a worldwide travel insurance company providing real-time medical following of patients with active medical issues during their travel, including AAA. This article reviews the existing recommendations with conclusions based on both these limited data and rationale conjecture.
Pathophysiology and Physics of AAA The pathogenesis of AAA is a multifactorial process leading to alteration in the aortic vascular wall connective tissue. In 109
general, the loss of elastin and replacement with collagen ultimately allows the aorta to enlarge, producing aneurysmal dilation. The abnormally dilated wall is subject to continued stress, placing the AAA at risk for rupture.4 The magnitude of risk is dependent on a range of factors, including size, rate of growth, shape, and active symptoms (ie, pain).3 Once an AAA has developed, sudden increases in blood pressure and ongoing hypertension are accepted as risk factors for rupture; furthermore, lowered atmospheric pressure may increase rupture rates. Commercial aircraft are not pressurized to ground-level pressure, but for economic and mechanical reasons, the cabin pressure varies between ground-level pressure and a maximum equivalent cabin altitude of 8,000 ft.5 Thus, there is a theoretic concern of an increased chance of rupture because of air travel at altitude in pressurized cabins of aircraft. In general, it must be recalled that lowered atmospheric pressure equals increased altitude. A growing body of literature has reported on the association of low atmospheric pressure and the risk of ruptured AAA. One UK study reviewed 5 years of data, correlating the rate of AAA rupture and atmospheric pressure; the investigators described 50 cases of RAAA, noting an associated lower mean monthly pressure and a higher occurrence of rupture.6 Other studies have shown similar associations; 1 Northern Ireland study noted a lower recent atmospheric pressure with AAA rupture,7 1 in Germany noted atmospheric pressure variations and AAA rupture,8 and 1 in Turkey reported seasonal atmospheric pressure variation associated with rupture.9 Conversely, several smaller series have failed to show an association between atmospheric pressure and rupture.10-13 Yet, these studies are all constructed differently, making a consensus statement difficult based on this literature. Applying this literature base to the issue of AAA rupture risk and air travel is challenging. The extrapolation of these atmospheric pressure variations to the AAA patient and air travel is difficult at best. In fact, the medical literature does not report cases of AAA that ruptured directly as a result of air travel. At most, there is an unproven, suggested association between air travel and AAA rupture; there appears to be a small, but measurable, association between lower atmospheric pressure and AAA rupture. There is some heterogeneity in the methods used to quantify lower pressure (ie, 4-day variation, lowest pressure in the preceding month, and average pressure in the preceding month), making it difficult to draw specific conclusions. The medical literature does not report cases of AAA that ruptured as a result of air travel. However, the medical literature does note 3 reported cases1416 of aortic dissection associated with air travel. Whether brief decreases in atmospheric pressure such as air travel affect AAA has yet to be shown.
Discussion of the Questions Is it safe to evacuate patients with a symptomatic AAA by air? Ruptured AAA has an extraordinarily poor prognosis with an estimated mortality rate of 88%.17 A systematic review by 110
Hoornweg et al18 of 60,822 patients noted an overall mortality rate for the surgical repair of ruptured AAAs of 48.5%. One center described their success in setting up direct to surgical suite transportation of unstable AAAs with leak by air transport.19 A retrospective series of suspected unstable AAAs transported from the field where 50% received surgical intervention showed 9% prehospital mortality.20 Faced with these statistics, there is little doubt that for the patient with a symptomatic or ruptured AAA, the benefits of surgical intervention outweigh the theoretic atmospheric pressure changes and the risk of air medical evacuation. Is it safe to repatriate patients with asymptomatic, symptomatic, or repaired AAA by air? And, the related question, if nonurgent travel is determined to be safe, what time interval is required to transpire from diagnosis and/or management of the AAA before allowing flight? There are extremely limited data about if, and when, it is safe for patients with asymptomatic AAAs to fly. The International Air Transport Association medical manual provides no specific guidelines on the need for medical clearance or safety of travel with an AAA. Although making no specific recommendation about flying after AAA surgical repair, the guidelines do require medical clearance to fly within 10 days of “cardiac surgery.” An Internet search using Google for “flying AND aortic aneurysm” revealed a small number of presurgical patient education pamphlets. These recommendations vary from “You should not fly anywhere for 6 weeks after your surgery”21 to “changes in cabin pressure during a flight may increase the risk of rupture of a large abdominal aortic aneurysm.”22 Although a different population, the UK Civil Aviation Authority allows for commercial pilots with an infrarenal AAA less than 5 cm to be licensed with the restriction that they always fly with a copilot.23 After surgical repair, pilots with an aneurysm of any size can be licensed with the same requirements. These guidelines provide no rationale for their recommendations. This risk is, at best, a theoretic concern that is not supported by scientific experimental data.22 Of course, the pressure changes during fixed wing air ambulance flight can be minimized by flying pressurized to sea level. Thus, medical “common sense” is the best guide for determining when a patient with AAA can safely fly in a nonurgent fashion on a commercial aircraft. The final question is is nurse accompaniment or other medical assistance needed during flight? There is no recommendation in the medical or flight literature commenting on the necessity of a medical attendant during flight. Furthermore, no data exist to support the need for a nurse or other medical accompaniment during a nonurgent, commercial flight, resulting solely from AAA. The presence of a medical attendant, whether an emergency medical service provider, nurse, or physician, on a commercial flight will likely not alter the outcome of a patient with an AAA that suddenly ruptures. Certainly, a medical escort can be provided for a postoperative patient who is debilitated or Air Medical Journal 33:3
deconditioned. Yet, the medical need in this example is not the AAA itself; in other words, medical accompaniment should be determined based on patient need and not simply the primary diagnosis.
Summary and Conclusions AAA presents across a spectrum of severity. Although some resources suggest a theoretic risk for rupture related to air travel, this claim remains unproven. In fact, there are little data from which to make evidence-based recommendations. Air medical evacuation of a patient with either an AAA at risk of imminent rupture or status post recent rupture can be performed, assuming that local surgical care is not available and that transfer is taking the patient to a higher level of medical intervention. Furthermore, medical opinion suggests that patients with asymptomatic and/or surgically corrected AAA can safely travel by commercial aircraft for nonurgent reasons, assuming that other issues including postoperative needs are appropriately addressed. The following are answers to our previous questions: 1. Is it safe to evacuate patients with a symptomatic AAA by air? Given the overwhelming mortality from unrepaired ruptured, leaking, or symptomatic AAAs, the benefits of rapid air medical transportation to definitive treatment are clear. In many cases, this transfer will occur by air ambulance; in this instance, the benefits of rapid transfer for definitive surgical care clearly outweigh the theoretic risks of an increased rupture rate caused by atmospheric changes related to air travel. 2. Is it safe to repatriate patients with asymptomatic, symptomatic, or repaired AAA by air? Again, the unproven risk of atmospheric pressure–related rupture must be balanced against the practical benefits of air travel. There is no literature (not even case reports) of air travel precipitating rupture in an asymptomatic AAA. Similarly, a surgically repaired AAA becomes an asymptomatic AAA. In the absence of another compelling reason (ie, surgical complication or other active comorbid issue) for delayed travel, these patients can likely travel safely via an escorted commercial airliner. 3. If nonurgent travel is determined to be safe, what time interval is required to transpire from the diagnosis and/or management of the AAA before allowing flight? The answer to this question is not found in the medical literature. Thus, medical “common sense” is the best guide for determining when the patient with AAA can safely fly in a nonurgent fashion on a commercial aircraft. 4. Is nurse accompaniment or other medical assistance needed during flight? Again, as mentioned previously, no scientifically based recommendation can be made in this instance. Medical judgment is best used in this consideration, realizing that the patient with a rupturing AAA likely will not have his or her outcome altered by a medical attendant. May-June 2014
References 1. Bureau of Transportation Statistics. Omnibus survey: household survey. Available at: http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/subject_areas/omnibus_sur veys/household_survey/2009/october/index.html. Accessed October 20, 2013. 2. Ashton HA, Buxton MJ, Day NE, et al. Multicentre Aneurysm Screening Study Group. The multicentre aneurysm screening study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised controlled trial. Lancet. 2002;360:1531-1539. 3. Chaikof EL, Brewster DC, Dalman RL, et al. SVS practice guidelines for the care of patients with an abdominal aortic aneurysm: executive summary. J Vasc Surg. 2009;50:880-896. 4. Wassef M, Baxter BT, Chisholm RL, et al. Pathogenesis of abdominal aortic aneurysms: a multidisciplinary research program supported by the national heart, lung, and blood institute. J Vasc Surg. 2001;34:730-738. 5. Aerospace Medical Association Medical Guidelines Task Force. Medical guidelines for airline travel, 2nd ed. Aviat Space Environ Med. 2003;74(suppl):A1-19. 6. Kordzadeh A, Askari A, Panayiotopoulos Y. Atmospheric pressure and infra-renal abdominal aortic aneurysm rupture: a single observational study and a comprehensive review of literature. Int J Surg. 2013;11:458-462. 7. Killeen SD, O'Sullivan MJ, Coffey JC, Redmond HP, Fulton GJ. Atmospheric pressure variations and abdominal aortic aneurysm rupture. Ir J Med Sci. 2008;177:217-220. 8. Schuld J, Kollmar O, Schuld S, Schommer K, Richter S. Impact of meteorological conditions on abdominal aortic aneurysm rupture: evaluation of an 18-year period and review of the literature. Vasc Endovascular Surg. 2013;47:524-531. 9. Rabus MB, Eren E, Erkanli K, Alp M, Yakut C. Does acute aortic dissection display seasonal variation? Heart Surg Forum. 2009;12:E238-240. 10. Kurtoglu M, Yanar H, Aksoy M, et al. Seasonality in the incidence of abdominal aortic aneurysm ruptures: a review of eight years. Ulus Travma Acil Cerrahi Derg. 2004;10:39-41. 11. Molacek J, Treska V, Kasik M, et al. Correlation between atmospheric pressure changes and abdominal aortic aneurysm rupture: results of a single-center study. Surg Today. 2013;43:1003-1037. 12. Repanos C, Chadha NK. Is there a relationship between weather conditions and aortic dissection? BMC Surg. 2005;15:21. 13. Verberkmoes NJ, Soliman Hamad MA, Ter Woorst JF, et al. Impact of temperature and atmospheric pressure on the incidence of major acute cardiovascular events. Neth Heart J. 2012;20:193-196. 14. Fozzato F, Prioli MA, Santini F, et al. Aortic intramural hematoma fissuration: atypical presentation in an aircraft pilot. G Ital Cardiol. 2010;11:162-164. 15. Ghosh AK, Lodge FM, Dubrey SW. Acute aortic dissection with a high D-dimer and pleuritic chest pain in an airline passenger. Clin Med. 2010;10:409-411. 16. Shaw KP, Ho BL, Lee WH, Fong JM. Rupture of dissecting aneurysm in a china airlines co-pilot. Forensic Sci Int. 1996;81:157-164. 17. Bengtsson H, Bergqvist D. Ruptured abdominal aortic aneurysm: a populationbased study. J Vasc Surg. 1993;18:74-80. 18. Hoornweg LL, Storm-Versloot MN, Ubbink DT, et al. Meta analysis on mortality of ruptured abdominal aortic aneurysms. Eur J Vasc Endovasc Surg. 2008;35:558-570. 19. Shewakramani S, Thomas SH, Harrison TH, Gates JD. Air transport of patients with unstable aortic aneurysms directly into operating rooms. Prehosp Emerg Care. 2007;11:337-342. 20. Mitchell AD, Tallon JM. Air medical transport of suspected aortic emergencies. Air Med J. 2002;21:34-37. 21. Royal Berkshire NHS Foundation Trust. Information for patients having an abdominal aortic aneurysm repair. Available at: http://www.royalberkshire.nhs.uk/pdf/ AAA.pdf. Accessed October 14, 2013. 22. Bedfordshire Vascular Unit NHS Foundation Trust. Abdominal aortic aneurysm: information for patients. Available at: http://www.rcsed.ac.uk/fellows/pvtisi/ Abdominal%20Aortic%20Aneurysm%20%20June%2012.pdf. Accessed October 14, 2013. 23. UK Civil Aviation Authority. Guidance for medical certification of aircrew: cardiovascular system 2012. Available at: http://www.caa.co.uk/default.aspx?catid⫽2499& pagetype⫽90&pageid⫽13796#Aneurysm. Accessed September 11, 2013.
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