Medical test signal generator and interface

1. A cardiac signal generator, comprising:

a first circuit configured to provide, according to any of predetermined plurality of settings, cardiac signals comprising a repeating cardiac waveform, and respiratory signals comprising a repeated respiratory waveform;

a user input device including a switching element;

an output display comprising a plurality of indicators, each indicator corresponding to one of the plurality of settings, each setting comprising a predetermined combination of a frequency of repetition of the repeating cardiac waveform in the cardiac signal and a frequency of repetition of the repeating respiratory waveform in the respiratory signal;

a processing circuit configured to

cause the first circuit to provide cardiac signals and respiratory signals according to a selected setting of the plurality of settings;

receive a signal from the user input device, wherein the user input device generates said signal responsive to each single actuation of said switching element;

change the selected setting from a first setting of the plurality of settings to a second setting of the plurality of settings responsive to receiving the signal from the user input device, such that said single actuation causes a change in the frequency of repetition of the repeating cardiac waveform and a change in the frequency of repetition of the repeating respiratory waveform, and such that a subsequent single actuation of the switching element causes a subsequent change in the frequency of repetition of the repeating cardiac waveform and a subsequent change in the frequency of repetition of the repeating respiratory waveform.

2. The cardiac signal generator of claim 1 , wherein the first circuit is configured to provide respiratory signals superimposed onto the cardiac signals.

3. The cardiac signal generator of claim 1 , wherein the plurality of setting includes six settings.

4. The cardiac signal generator of claim 1 , wherein each indicator is a two-state indicator, and wherein the processing circuit is further configured to change a state of a first indicator corresponding to the first setting and change a state of a second indicator responsive to receiving the signal.

5. The cardiac signal generator of claim 4 , wherein each indicator comprises a light-emitting diode.

6. The cardiac signal generator of claim 1 , wherein the processing circuit is further configured to cause a transition to a first state in which the first circuit stops providing cardiac signals responsive to the switching element being continuously in an open state for a predetermined time period.

7. The cardiac signal generator of claim 6 , wherein the processing circuit is further configured to cause a transition from the first state to a second state in which the first circuit generates cardiac signals responsive to actuation of the switching element.

8. The cardiac signal generator of claim 7 , wherein the processing circuit is further configured to cause a transition from the second state to the first state responsive to continuous actuation of the switching element for a predetermined period of time.

9. The cardiac signal generator of claim 1 , wherein the first circuit includes at least a portion of the processing circuit.

10. The cardiac signal generator of claim 9 , wherein the first circuit further comprises a digital to analog circuit coupled to the processing circuit, and a potentiometer coupled to the processing circuit.

11. A cardiac signal generator comprising:

a first circuit configured to provide, according to any of predetermined plurality of settings, cardiac signals comprising a repeating cardiac waveform, and respiratory signals comprising a repeated respiratory waveform;

a user input device including a switching element;

an output display comprising a plurality of indicators, each indicator corresponding to one of the plurality of settings, each setting comprising a predetermined combination of a frequency of repetition of the repeating cardiac waveform in the cardiac signal and a frequency of repetition of the repeating respiratory waveform in the respiratory signal,

wherein each indicator is disposed adjacent to indicia on a device housing, each indicia corresponding to the one of the plurality of settings corresponding to the indicator;

a processing circuit configured to

cause the first circuit to provide cardiac signals and respiratory signals according to a selected setting of the plurality of settings;

receive a signal from the user input device, wherein the user input device generates said signal responsive to each single actuation of said switching element;

change the selected setting from a first setting of the plurality of settings to a second setting of the plurality of settings responsive to receiving the signal from the user input device, such that said single actuation causes a change in the frequency of repetition of the repeating cardiac waveform and a change in the frequency of repetition of the repeating respiratory waveform, and such that a subsequent single actuation of the switching element causes a subsequent change in the frequency of repetition of the repeating cardiac waveform and a subsequent change in the frequency of repetition of the repeating respiratory waveform.