How can airway resistance be measured in very young and elderly patients?

Body plethysmography is the preferred method for measuring airway resistance in very young and elderly patients. This technique involves the patient sitting inside an airtight chamber, allowing for accurate assessment of lung function. It is particularly useful for those who may not be able to perform spirometry effectively due to their age or ability.

In the case of the very young, such as infants, cooperation and the ability to follow instructions during testing can be challenging; therefore, body plethysmography provides a more relaxed and controlled environment for obtaining reliable measurements. For elderly patients, who may also have difficulty with maneuvers required for spirometry, body plethysmography can help circumvent these challenges by using passive measurements instead of forced expiratory maneuvers.

On the other hand, spirometry, while useful for measuring flow rates and volumes, relies on the patient's ability to perform forced expiratory maneuvers, which can be challenging for both very young children and elderly individuals. Pulse oximetry measures oxygen saturation but does not provide information about airway resistance, and capnometry measures carbon dioxide levels, also not related to resistance in the airways. Hence, body plethysmography stands out as the optimal choice for assessing airway resistance in these patient populations.