You are about to deliver anesthesia in a chaotic emergency situation. The operating room (OR) desk paged you in the cafeteria to tell you that a patient is coming over from the floor with a carotid blowout. The surgical intern is riding on the stretcher to apply pressure to the bleeder. You are told that there are blood products in the blood bank but that you have to call down there stat and let them know what to pack in the cooler. The problem is, you don’t know the name of the patient. You ask the person who is on the OR desk to identify the patient, but due to background noise in both the OR and the cafeteria, you cannot catch the name she says. It might be Atkins, it might be Adkins, or it might be Adams. You just can’t hear. You ask several times, each time a little louder. She replies, each time a little louder. You still can’t hear the name, and you feel yourself getting tachycardic. Suddenly, on the telephone, you hear the calm voice of your CRNA colleague (who served as a U.S. Air Force medic in Vietnam), saying slowly, “The patient is Alpha-Delta-Kilo-India-November-Sierra.” Armed with the correct information, you place the appropriate call to the blood bank. Mr. Adkins does fine.

Spelling alphabets are also commonly called radio alphabets, telegraph alphabets, or police letters. There are a number of different versions, but each uses a single phonetically distinct word to replace the name of the letter with which it starts. Spelling alphabets have their origins deep in military and communications history, and have been used at least since the beginning of the 20th century. They arose because early aviation and military radios were plagued by static. Because so many letters in the English language are phonetically similar (e.g., B, C, E, T, D, P), a burst of static would have made it impossible to accurately transmit letter-based information. Thus, in World War II, the sequence B-E-D would have been “called” as Baker-Echo-Dog. Spelling alphabets are used in at least 30 languages (from Finnish to Urdu), and there is a numeric code as well. Spelling alphabets are often called phonetic alphabets, but this is actually a misnomer. Phonetic alphabets are written representations of spoken sound as opposed to spoken representations of written symbols.

ORs are noisy places. Decibel levels have been measured under a variety of situations and for different types of procedures. The “average” noise in a routine case will approach 70 to 80 db. In certain orthopedic procedures, such as total joint replacement, noise levels are routinely 110 db, which is the same level of noise in some boiler rooms, and will intermittently approach 140 db, which is high enough to put the surgeons (and other OR staff) at risk for occupationally associated hearing loss.

Operating noise is known to have detrimental effects on anesthesia providers. In a study by Murthy et al., when anesthesia residents were exposed to a 90-minute cassette of OR noise at 77 db, they had lower scores on tests for mental efficiency and short-term memory. More important, the same noise level significantly affected both speech reception threshold and speech discrimination, which led researchers to conclude that there is a marked decrease in the ability to discriminate spoken words at ambient OR noise levels. The use of a spelling alphabet may, therefore, have the same efficacy for anesthesia providers as for the military and pilots.