When considering safe flight, caffeine must be considered a drug, no matter where you find it. It also ends in “ine,” which indicates it could affect your performance as a pilot. Its use is a mild addiction for some people, or, at the very least, a strong habit. It is one of the most common drugs that can be purchased over the counter as part of a beverage. It is a part of our family, business, and social life style. For many, coffee is a staple of life, without which they are incapable of functioning properly, or so they think. For some pilots, a cup of coffee is a part of their after-takeoff checklist. But caffeine, like alcohol, when used to excess in some people can cause problems result- ing in a variety of physical and mental dysfunctions. Caffeine from any source is one of the most underrated of all readily available mood-altering drugs, one that causes potentially unsafe problems, especially in and after flight. It is also considered to be addictive; that is, the body needs the extra stimulation to function and will have withdrawal symptoms.
Caffeine 167 Caffeine increases heart rate and can disturb pulse rhythm, constricts blood- vessel diameters and coronary circulation, increases urine production and excretion (diuretic), and disrupts normal mental processes. Tolerances vary among different people, some noticing few if any side effects, others noticing significant unwanted symptoms, even with only one cup of coffee. In other words, it is a habit-forming stimulant with unpredictable side effects to an individual as well as problems of withdrawal when stopped.
Sources
Perhaps the most common sources of caffeine are coffee, tea, and high energy beverages (Fig. 9-2). Regular brewed coffee has an average of 100 mg of caf- feine per cup. Decaffeinated coffee has only about 4 mg, but it is still present and will affect those that are very sensitive to caffeine. Tea has about 70 mg per cup (or glass of iced tea). Others include a cup of cocoa (50 mg), cola drinks (40–70 mg per 12 ounces), and chocolate (15 mg). And recall that caffeine is present in many OTC medications, often as the “extra-added ingredient.”
It is easy to compute how caffeine intake in a 24-hour period could reach significant levels when considering all these sources. Intake in excess of 250 mg is symptomatic in most people who have not built up a tolerance over the years, with symptoms becoming more noticeable in very sensitive people.
Some pilots are not aware that some of their fatigue, headaches, insomnia,
Figure 9-2
Figure 9-2 Caffeine content.
168 Self-imposed medical stresses
and nervousness could be secondary to their caffeine intake. Others notice a change in their heart rhythm (skipped beats) in addition to heart rate after just one cup, and this can show up on their FAA EKG (if the EKG is required).
Coffee is a strong stimulant, which is the reason most people use caffeine.
The morning ritual of waking up often includes coffee. It’s often the first thing offered to you in the morning at a restaurant. It is estimated that Americans drink more than 370 million cups of coffee per year, which means that nearly one in five Americans drinks more than five cups of cof- fee a day (that’s about 500 mg); however, one to two cups is usually well tolerated and for some people does diminish fatigue, improve mood and alertness, and temporarily increase mental and physical work capacity. It is one of the drugs of choice in trying to control circadian change and fatigue on long flight days. The withdrawal effects after the trip, however, can be counterproductive.
Side effects
Because caffeine is a stimulant to the central nervous system, some people are unable to sleep if they ingest caffeine as long as several hours before retiring. This can be a true dilemma if the pilot uses coffee to stay awake on a long trip and then subsequently tries to get to sleep on the layover. For some people, just one cup of coffee or tea in the afternoon or evening is enough to keep them awake.
Caffeine is also a strong cardiac stimulant, acting like adrenaline to the heart muscle and often increasing pulse rate. Some evidence states that blood pres- sure is raised, but that is less of a fact than its effects on pulse and rhythm.
Arrhythmias, such as “skipped beats” or premature ventricular contractions (PVCs), and other irregularities, might not be clinically significant, but if they show up on an EKG, such as with a company or FAA exam, they have to be explained. This means other possible causes must be ruled out. Pilots have been grounded for this situation until the evaluation is completed satisfacto- rily and no other problems are discovered.
Caffeine is also a diuretic (increases urine production and excretion). In other words, one cup of coffee could result in urinating two or more cups of water, creating a negative fluid balance that makes dehydration even a bigger prob- lem than what is usual in the cockpit (due to reduced humidity at altitude and in a pressurized cabin or cockpit). Because of the additional chemical theophylline, tea can be a stronger diuretic than the same amount of coffee.
One can see that iced tea, especially during the summer, can be refreshing, but as a diuretic, it can also be more dehydrating in an already dehydrating environment. Cola beverages are very popular and are consumed all day, even for breakfast.
One of the most serious yet subtle side effects is on mental functions, often calledcaffeinism. It can cause anxiety and panic disorders, worsen premen- strual syndrome, and create headaches and nervousness. This becomes par- ticularly true during withdrawal from caffeine. Swings of heavy intake, as on a trip or studying for exams or checkrides, to minimal amounts during