Is a nose just a nose?

A little over a decade ago, passive humidifiers, ¦^^ commonly called "artificial noses," were rele¬ gated to short-term use, typically less than 24 h. Improvements in design, coupled with careful clini¬ cal investigations, have proven that in select patients, passive humidifiers can be used safely for several days.15 The definition oi several is currently debat¬ able, but evidence for up to 5 days is abundant. Despite a plethora of publications on the subject, there remain several unsettled issues related to the use of passive humidifiers. One of these questions is answered quite nicely in a deceptively simple study by Beydon and colleagues in this issue of CHEST (see page 739). The question is, 'how do you know if the device is working properly?' Beydon et al corre¬ late measurements of humidification adequacy; se¬ cretion abundance, secretion viscosity, and adher¬ ence of the suction catheter to the endotracheal tube to the presence of condensate in the flex tube between the passive humidifier and the patient. Their results suggest that the presence of condensate in the flex tube signals adequate humidifying effi¬ ciency. This information may also be used to compare brands of passive humidifiers. Devices that fail to demonstrate condensate in the flex tube could be considered inferior to those which readily create condensate. Beydon et al address this in a section of their study comparing a hygroscopic device to a heat and moisture exchanger. Their results show what others have found previously, that hygroscopic de¬ vices are more efficient than devices that rely on physical exchange of heat and water alone.68 Concerns surrounding the use of passive humid¬ ifiers remain. Humidification is often ignored and relegated to an unimportant adjunct to mechanical ventilation. However, cost savings associated with passive humidifiers may tempt clinicians to use them outside of their intended scope. I strongly believe that the humidification needs of patients need to be assessed on a patient-to-patient, day-today basis. Humidification devices should be chosen based on the intended duration of use, patient's previous respiratory health, quality of secretions, and desired therapeutic effect. Simi¬ larly, if a passive humidifier is used, the device should be evaluated with respect to moisture output, resistance, deadspace (compared to pa¬ tient tidal volume), and cost.9 Finally, some pa¬ tients require heated humidification! The pres¬ ence of condensate in the flex tube may indicate the efficiency of the device, but this does not guarantee that the …