Which setting adjusts the height of the EKG waveform on tracing?

The gain control setting is responsible for adjusting the height of the EKG waveform on the tracing. In the context of an EKG machine, gain refers to the amplification of the electrical signals received from the heart. By increasing the gain, the amplitude of the waveform appears taller, making it easier to analyze the details of the heart's electrical activity. Conversely, decreasing the gain results in a shorter waveform.

Other settings, such as speed control, primarily affect how quickly the paper moves through the machine, thereby influencing the time scale of the tracing rather than the height of the waveform. The lead selector is used to choose which lead’s data is being monitored or printed, and the paper feed control manages how much paper feeds through the printer. Each of these controls serves important purposes but does not directly affect the height of the EKG waveform like gain control does.