Final answer:
To confirm CPAP pressure, a manometer is used. This device measures the pressure of gases, suitable for checking the pressure in CPAP devices, unlike sphygmomanometers or spirometers which measure blood pressure and lung function, respectively.
Step-by-step explanation:
To confirm CPAP (Continuous Positive Airway Pressure) pressure, the correct tool is a manometer. This device is specifically used for measuring the pressure of gases, not liquids. In the treatment of sleep apnea, CPAP devices use a manometer to ensure the air being delivered maintains the prescribed pressure to keep the airways open during sleep. This is different from sphygmomanometers, which are used to measure blood pressure, and spirometers, which assess lung function, not pressure. Photometers are used for measuring light intensity, and thus, are not relevant to measuring CPAP pressure.
An example of how a manometer works can be found in gas pressure measurements. When using a closed-end manometer filled with mercury to measure the pressure of a gas, the reading could be taken in different units such as torr, Pascal (Pa), or bar. To calculate the gas pressure using a manometer, one would look at the difference in mercury levels in the two arms of the manometer and take into account atmospheric pressure if it's an open-ended manometer.