### The** Gases** module is designed to detect inspired and end-tidal gas concentrations of O2 and CO2 respectively.

- Activate the channel.
- Select the channel that corresponds to CO2 and O2.
- Select the appropriate input units (either mmHg or %). If your raw data is recorded in %’s you can convert the signal to mmHg by selecting
**unit conversion**and specifying the corresponding**atmospheric pressure**. - Adjust the
**width**and**threshold**parameters to identify the partial pressure of end-tidal CO2 and inspired O2. - Click
**OK**to stored results. - Exist the module and analyse other signals or
**SAVE**the file.

### Control definitions

Control | Definition |
---|---|

Channel | Activates the channel. |

Channel select | Specifies the channel that corresponds to respiratory CO2 and O2 signals. |

Input units | Specifies the raw units. Options are either mmHg or %. |

Atm Pressure | Specifies the atmospheric pressure required for converting % to mmHg. The atmospheric pressure should be specified in mmHg. |

Method | Specifies whether the algorithm looks for peaks or valleys in the input signal. |

Range type | Specifies the axis to which the bounds in Range apply. Default is Y-axis (corresponds to partial pressure or gas concentration). |

Width | Width specifies the number of consecutive data points to use in the quadratic least squares fit. width is coerced to a value greater than or equal to 3. The value should be no more than about 1/2 of the half-width of the peaks/valleys and can be much smaller (but > 2) for noise-free data. Large widths can reduce the apparent amplitude of peaks and shift the apparent location. For noisy data, this modification is unimportant since the noise obscures the actual peak. Ideally, width should be as small as possible but must be balanced against the possibility of false peak detection due to noise. |

Threshold | Threshold instructs the algorithm to ignore peaks and valleys that are too small. The algorithm ignores peaks if the fitted amplitude is less than threshold. The algorithm ignores valleys if the fitted trough is greater than threshold. |

Range | Range specifies the upper and lower bounds of the range. This algorithm removes data points that lie on or outside the bounds of Range. If range type is Y or X, this algorithm uses the first two elements in Range as the upper and lower bounds, respectively, for the given axis. If range type is X and Y, this algorithm uses the first and second elements in Range as the upper and lower bounds for the x-axis and the third and fourth elements in Range as the upper and lower bounds for the y-axis. |

OK | Stores results |