Volume 5, No. 1 • Spring 1990

Noise and Alarms: Dangerous Distractions

David V. Thomas, M.D.

To the Editor

Two underemphasized factors, I believe are increasingly contributing to human error during the administration of anesthesia. They deserve the attention of anyone studying anesthetic accidents and their prevention.

First, there has been a great increase in the amount of ambient noise in the modem operating room. Every newly introduced piece of equipment makes its own contribution.

Noise generators in a typical operation room include:

1. Air conditioning inflow

2. Warming cabinet (fan)

3. electrocautery (fan and tone)

4. C02 analyzer (fan)

5. Surgical suction sometimes two (constant hiss)

6. Gas-powered Ohio anesthesia ventilator (constant hiss, and intermittent cycling noise)

7. Tape-recorded music or radio, playing at desire of surgeon or anesthesiologist, or both (never at my desire!)

Additional sources in special areas are:

8. Operating microscope (fan)

9. Opthalmic cutter-evacuation (constant pump noise)

10. Laser (fan)

11. Vapor evacuator for orthopedic cement (fan)

12. Red-cell processor (suction and centrifuge)

13. Heart-lung machine (rotary pumps)

When many of these things are going, it is more like working in a factory than in an operating room. I believe that this high level of noise detracts from patient safety (a) by impairing communication among the members of the team, and (b) by distracting the anesthesiologists attention. I know of several near accidents when a ventilator was turned off, supposedly for a short time to facilitate some surgical maneuver, and the anesthesiologist faded to switch it on again. In older, quieter days one could not fail to notice the absence of the intermittent cycling sound but now, with so many fans humming and music playing, it is easy not to notice that the ventilator is silent.

An additional factor in my hospital is that, since the operating suite was remodeled a few years ago, the accous6cs have been changed greatly for the worse. I don’t know exactly why I presume that it is dependent upon the sound-reflecting and sound distoring qualities of the wall, floor, and ceding surface but when a paper package is opened (and there are many) the noise created by the tearing or crushing of the paper drowns out any words being uttered in the room at that moment.

I believe the problem of noise should be brought to the attention of manufacture so that designers and engineers could pay more attention to it and seek solutions.

The second factor which urgently requires study is the confusion produced by the proliferation of alarms. There are so many buzzers, whistles, and beeps several resembling each other yet no logical system or arrangement exists.

Here is a list of alarms in a typical modern operating room:

1. Well-mounted gas pressure alarms for oxygen, nitrous oxide, compressed-air, surgical vacuum, gas evacuation, and nitrogen

2. Wall-mounted alarm for faulty electrical ground

3 . High or low heart-rate EKG monitor

4. High or low reading on intra-arterial pressure monitor

5 . High or low reading on non-invasive blood pressure monitor

6. High or low pulse rate, high or low saturation on pulse oximeter

7. High or low inspired oxygen on oxygen analyzer

8. High or low reading on end-tidal C02 analyzer

9. High or low temperature on electric thermometer

10. Ventilator disconnect alarm

11. Electrocautery “switched-on” signal 12. electrocautery faulty ground alarm

13. Electro-cautery signal indicating use of cauterizing current

14. Electro-cautery signal indicating use of “cutting” current

Each one of these has a buzzer, or a “beeper” or a gong or an oscillating sound. Some sound off so infrequently that is hard to remember where they are in the room and what they signify. Others go off so often that they are commonly turned off!

All of these machines are making great contributions to patient care so, of course, they are necessary. The point I wish to make is that it is time for manufacturers to get together, as they have done with other anesthetic equipment (e.g. endotracheal connections) to bring some order out of this chaos. Ideally, one alarm sound could serve for all with a verbal message on a screen or LED identifying the problem.

David V. Thomas, M.D. Los Altos, CA