Monday, March 19, 2012

From your Kiwi Correspondent Part I

“Hello there, this is your captain speaking. Today, we’re going to skip the details about your personal flotation device… if you find yourself needing that, well, talk about one in a bazillion…And I know that you know how to click together a bloody seatbelt. Our seatbelts work like every other one you’ve ever used, and if you can’t figure it out, well, perhaps you shouldn’t be out in public in an unsupervised fashion. So instead, why don’t you pay attention to some health tips that might actually be useful.”
Don’t you wish airline pilots would give it to you straight like that? I sure do. 

Recently, I took a twelve-hour flight from Los Angeles to Auckland, New Zealand and, as it turns out, twelve hours is a long time to spend on a plane. Especially if you’re seated next to a hulking rugby player whose taut triceps nudge you into an awkward diagonal position. The good news is that this (seemingly interminable) discomfort gave me plenty of time to consider what is really worrisome about an extended plane flight. And you know what, the location of the personal flotation device is not high on the list. In fact, the Transportation Safety Board of Canada, among others, has concluded that even in the rare circumstance that such a device be required, it is highly unlikely that it will be used unless the passenger is actually wearing it beforehand. And since I’m not interested in advice (such as wearing a life vest for the duration of an overseas flight) that makes flying even more uncomfortable, we shall focus on more tangible threats. 

1       Deep Vein Thrombosis (DVT): “Stretch your bloody legs.”

We all know that DVT is a common and potentially deadly condition and that prolonged immobility is a major risk factor. But how common is the airline DVT, dubbed by some as “Economy Class Syndrome”? We don’t know for certain, but some estimates are staggering. In 2001, The Lancet (Scurr et al) published an analysis estimating that one million cases of DVT related to air travel occur in the U.S. each year and that 100,000 of these result in death. A more recent review article by Gavish and Brenner put the risk on long-haul flights (6 ½ hours or longer) at 3-12%. This is a pretty stunning incidence – equaling approximately one DVT per one to four rows of economy seats in a Boeing 777. The American College of Chest Physicians (ACCP), on the other hand, have – in both their 2008 and 2012 guidelines – estimated a lower incidence, calling the risk “mild.” It’s thought that the risk of DVT is due not only to in-flight immobility but also the relative hypoxia in the cabin. As with all DVTs, risk factors include age over 40 years, female gender, pregnancy, oral contraceptive use, lower limb varicose veins, obesity, and genetic thrombophilia. The ACCP has recently added sitting in window seats to this list (Grade 2C evidence) while also observing that “Economy Class Syndrome” may be a misnomer – those in first class have the same DVT risk as those in the back of the plane. Notably, even the absence of risk factors does not put you in the clear. A Norwegian study (The Lancet, 2000) observed a substantial hour-by-hour increase in blood clotting factors (2-8 fold) occurred in all twenty healthy subjects studied in a simulated (hypobaric) environment.

Clearly, even if Economy Class Syndrome is a misnomer and some incidence estimates overblown, it seems that DVT prevention advice would be a useful aspect of an in-flight safety program (more helpful, perhaps, than a reminder to stow your tray table in an upright position.)

The trick to prevention, as we all know, is to keep those bloody legs moving! Any combination of the following will help: 1) graduated compression stockings for high risk patients at 15-30 mg of Hg, 2) calf and ankle exercises such as pumping up and down on the balls of the feet for 2-3 minutes every half hour, and 3) frequent walks up and down the aisles. Some evidence suggests that patients in high-risk demographics may benefit from a prophylactic anti-thrombotic – with low-weight molecular heparin (LMWH) likely being the best (but not so convenient) choice. A comparative study by Cesarone et al. published in Angiology, found that LMWH (given two to four hours pre-flight) was statistically superior (no DVTs in 82 subjects) to control (4/82) and aspirin alone (3/84). The current ACCP guidelines, however, do not recommend routine anti-thrombotic therapy, even for high-risk patients. Thus, it’s not likely that we will soon see “Leg Care Clinics” popping up in international terminals to offer a quick pre-flight shot of anti-DVT elixir. 

Dehydration: “Drink some blasted sports drink.”

It’s so easy to get dehydrated when traveling. There’s the dry air of a pressurized cabin, the mile-high altitude, and the stress and exertion of it all. With dehydration can come fatigue, grumpiness, a wicked headache, and (perhaps) an increased risk of DVT. So, what is the best way to stay hydrated? Common sense dictates that one avoids excessive alcohol and limit caffeinated beverages. But, what about drinking water? A 2002 JAMA study by Hamada et al. found that in-flight blood viscosity is better controlled with an electrolyte-enhanced beverage (110 mg of sodium and 30 mg of potassium per 8 oz) versus water alone. Perhaps your flight attendant should be serving Powerade rather than punchless coffee? Since that’s not likely to happen, bring packets of sports drink powder to mix with flight beverages.

The dry air of a plane can parch external body parts too – like the nose, eyes, and skin. A bloody nose or corneal abrasion at 30,000 feet is not going to help anyone sit back and enjoy the flight. So, for at-risk folks, Vaseline for the nostrils and liquid tears for the eyes are great ideas.  

Dry skin can be a real issue too – and believe it or not this has been documented in the literature. A French study of eight volunteer long-haul airline passengers observed that in-flight skin capacitance decreased rapidly on both the face and forearms – with the most pronounced changes on the cheeks where it decreased by up to 37%. So, how about some aloe vera to go with that moist towelette?

The good news about the arid airline air is that it helps keep infectious organisms at bay. Thus, I wouldn’t worry too much about the cabin air circulation, but would, of course, worry about a febrile-appearing lady with a productive cough sitting right next to me.  

      Physical abuse from your surroundings: “Avoid the pill-popping rugby player."
      I am well aware that carry-ons can tumble out of the overhead storage bins and that tall guys, like me, can bonk their heads, but accidental strangulation by a fellow passenger? That hadn’t occurred to me until several hours and two movies into our flight to Auckland. I sat crookedly next to my large and slumbering neighbor and resolved to fall asleep. Suddenly, though, a fire-siren-like scream rocketed through the cabin and a log-sized arm pinned my neck against the seat. Fortunately, the arm relaxed and I breathed again as my seatmate stood up, still screaming, and starting shaking the row in front of him. It all looked like an impromptu Maori war dance, the Haka. Luckily for me, and for the economy class as a whole, this hulking fella had some equally large friends with him – they jumped to his (and my) aide. Later, as they mercilessly ribbed him, I learned that he’d taken a double dose of Ambien, which had contributed to a very realistic nightmare. Why hadn’t my captain warned me about this. 

     Well, there you go, a brief guide to keeping the skies health friendly. Oh, and please do not forget, systematic reviews have established that “tampering with, disabling or destroying the lavatory smoke detectors is prohibited by law.”

      Kia Ora (Cheers) from New Zealand.