Aug 072018
 

Jon-Emile S. Kenny MD [@heart_lung]

I’m learnin’ to fly … but I ain’t got wings … comin’ down … is the hardest thing.”

-Tom Petty

Common Events Continued …

Abdominal Pain

Like chest pain, abdominal pain carries a wide differential diagnosis.  Abdominal pain comprises 4% of all in-flight events and 10% of all diversions.  An antacid may be administered to help with indigestion and education about Boyle’s Law at altitude may help explain acute, colicky pain secondary to viscus expansion.  With dehydration in-flight, renal colic should be considered on the differential and emergency medical kits aboard US carriers will carry normal saline and a basic IV kit.  Anti-emetics such as ondansetron may be available from passengers; as well, diphenhydramine may provide some relief while being wary of its side-effects.  As below, symptoms or signs of abdominal catastrophe should prompt a diversion recommendation.  Obstetrical events are especially uncommon but nicely-reviewed here.

Respiratory Distress

About 12% of in-flight medical events involve respiratory complaints.  Certainly, dyspnea may be anything from anxiety to obstructive airways disease to severe cardiovascular or pulmonary vascular misadventure; therefore – like the other common in-flight complaints – the ill passenger should be triaged based on demographics, severity and duration of symptoms.  Auscultation of the lungs with ambient cabin noise is near impossible; as such, clinical judgement coupled with ground-based consultation is paramount.  Should hypobaric hypoxemia play a role in exacerbation of obstructive airways disease, a bronchodilator may be considered; this medication can be found in the EMK or from another passenger.  If a nebulizer is needed, consider the ‘Dr. Guru’ technique.  Like acute coronary syndrome above, it has been recommended that the plane descend to lower altitude, but this carries aviation risk.  In lieu of descending to lower altitude, I have wondered if inquiring other passengers for a CPAP machine with bleed-in oxygen might buy time in a particularly dyspneic patient; otherwise, bag-valve mask ventilation can raise alveolar pressure and oxygen tension and abrogate breathing work.  Vitally, administering oxygen at 2 L/min at a cabin pressure of ~ 8000 feet provides an inspired oxygen tension equivalent to sea level.

Cardiac Arrest & Neurological Misadventures

Call for an automated external defibrillator [AED] in the unresponsive passenger; many AEDs have a rhythm display which can help guide management and flight attendants are trained in AED use.  Additionally, immediate IV access should be obtained – consider both IV dextrose and/or naloxone depending on the fingerstick.  The differential of unresponsiveness in-flight includes vascular, infectious, and metabolic/pharmacologic etiologies; administer oxygen.  If the patient is in cardiac arrest, this is a very uncommon in-flight emergency accounting for less than 0.5% of all events.  Compression-only CPR and discharge of an AED are the most important interventions at altitude; the recent publication of the PARAMEDIC2 trial calls into question administration of 10 mL of one-in-ten-thousand [1:10000] epinephrine [i.e. 1 mg] intravenously. Following 20-to-30 minutes of pulseless CPR, it is considered appropriate to cease compressions as survival is exceedingly unlikely.  In-flight, only a physician can pronounce death, though this is discouraged for medico-legal reasons.

Cerebrovascular accidents are the cause of nearly 2% of medical emergencies on commercial airlines and 16% of all flight diversions.  A full neurological examination is likely impossible in a passenger cabin and aspirin should be withheld given the possibility that the cause of a focal, neurological sign is not secondary to vascular occlusion [e.g. metabolic event or hemorrhagic event].  The patient’s glucose should be checked and, as above, oxygen may be administered.  If non-reversible deficits persist, discussion with ground-based consultation should favour diversion.  Suspicion of transient ischemic attack is a challenging situation in-flight; the need for emergent landing should be considered based on clinical gestalt and discussion with ground-based medical assistance.

While status epilepticus is a clear medical emergency requiring prompt diversion, its management in-flight is exceptionally challenging.  Patients should be moved away from trauma hazards and nothing should be placed within the mouth.  Not all emergency medical kits contain IV benzodiazepines or anti-epileptic drugs.  As an absolute last resort, other passengers may be asked for oral benzodiazepines that may be crushed and given rectally.  In an uncomplicated, self-resolving seizure in a patient with known epilepsy, immediate landing is typically not required and the patient may be treated with an additional dose of his or her own anti-epileptic drug.  A new seizure carries a similar differential diagnosis to unresponsiveness above.

The response of a physician to an unruly patient is nebulous and precarious.  An acutely agitated, psychotic, or violent passenger may be sedated with a benzodiazepine, though this has led to death.  As previously reviewed, the 1963 Tokyo Convention allows passengers to take any measures needed to safeguard others on the flight.  A physically-restrained passenger may require 4-5 individuals to assist and should be placed in the left-lateral decubitus position with frequent monitoring as the etiology of agitation may be surreptitious sedative use by the passenger – or polypharmacy – with delayed onset.

Acute allergic reactions

These are quite uncommon and represent 2-3% of all in-flight medical events.  Typically, allergic events can be managed with diphenhydramine and – in severe cases – subcutaneous epinephrine.  This brings up the important distinction between 1:1000 [one-thousand] and 1:10000 [ten-thousand] dilutions of epinephrine – both of which will be found in the emergency medical kit of US-based carriers.  The former – 1 in one-thousand – is more concentrated and contains an entire milligram of epinephrine per mL.  A small aliquot of this concentration [0.3 – 0.5 mL or 300 to 500 micrograms of epinephrine] can be administered if there is a severe allergic reaction; the preferred route of administration is intramuscular - into the vastus lateralis.

When to Divert?

Importantly, the ultimate decision to divert the aircraft and make an unscheduled landing lies entirely with the pilot.  The role of the health-care provider is to provide assistance in caring for the patient and act as a therapeutic conduit for ground-based consultative services.  It has been estimated that a flight diversion may cost an airline carrier up to $900,000 U.S. Dollars in addition to the risks inherent to urgently landing a plane at an unplanned destination.  Recommending diversion is likely best done in discussion with ground-based consultation, nevertheless, the following clinical situations have been advocated as justification for diversion by previous authors:

  1. Chest pain, shortness of breath, or severe abdominal pain that does not improve with use of the recommended initial interventions.
  2. Cardiac arrest
  3. Concern for acute coronary syndrome
  4. Severe dyspnea
  5. Persistent unresponsiveness
  6. Stroke
  7. Refractory seizure
  8. Severe agitation

Clearly, this list is not exhaustive and other, medically-dire situations may necessitate diversion – e.g. a severe allergic reaction with upper airway compromise.

Medicolegal Aspects

In 1998, the Aviation Medical Assistance Act [AMAA] was passed and this legislation provides protection to medically-qualified passengers who volunteer and render care; though, there must be no monetary compensation for the care administered.  Notably, travels vouchers, upgrades or goods do not qualify as compensation.  Explicit in the AMAA is the provision that care is neither grossly negligent nor is there willful misconduct on the part of the clinician; it should be apparent that assisting whilst intoxicated is grossly negligent.  It has been reported that there has never been successful litigation against a physician for acting in good faith, though there has been unsuccessful legal action.

Lastly, in North America and the United Kingdom, physicians do not have a legal duty to offer care in-flight, but this is not universal.  Some jurisdictions do mandate care when possible.  Typically, the laws of the country in which the airline is based supersede – though this is not absolute.

Return to the Case

You move the patient to business class, give him oral rehydration therapy and instruct him to lay flat with his legs slightly elevated by pillows.  Within the basic medical kit you find two large compression bandages which you wrap around his legs to augment venous return.  Further, you suspect that he has diminished venous return from histamine-related venodilation – secondary to the shellfish and red wine; he accepts 25 mg of diphenhydramine PO.  You return to your seat and watch another episode of ‘It’s Always Sunny In Philadelphia;’ when you re-evaluate him, he states that he feels much better.  As a token of gratitude, you receive a warm smile from the flight attendant and are upgraded to first class until arrival at Schiphol. 

Part 1

Best,

JE

Dr. Kenny is the cofounder and Chief Medical Officer of Flosonics Medical; he is also the creator and author of a free hemodynamic curriculum at heart-lung.org

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In-Flight Medical Events & Emergencies: part 2