We have shown a very good reproducibility and an excellent agreement with an office pneumotachograph and both pulmonary function electronic monitoring devices. Additionally, we confirmed the low accuracy and the nonlinear response of the Mini-Wright PFM. The best agreement with the pneumotachograph was observed for PiKo-1 FEV1, and the worst was observed for Mini-Wright PEF.
The inadequate performance of the Mini-Wright PFM is consistent with the observations of other studies. In fact, a model with a different scale has been introduced in the market to reduce errors. The lack of linear response is not necessarily characteristic mechanical PFMs.
To our best knowledge, no studies have been published regarding the clinical performance of the PiKo-1 or Spirotel devices. Other home spirometers and electronic monitoring devices have been studied, indicating their performance is fairly adequate for different clinical situations.
Limitations and Strengths
Our participants had a relatively high pulmonary function, which is probably related to the clinical stability inclusion criterion. This criterion was set in order to ensure the security of the protocol and to avoid maneuver-induced bronchospasm. These objectives have been achieved as indicated by the observation of measurement values (data not shown) and the minimal change in the dyspnea scale after the maneuvers. Nevertheless, the population studied is quite typical of the asthma patients seen in most medical settings, as the majority of asthma severity is mild, and also patients with more severe asthma have normal or near-normal pulmonary function after adequate treatment. In fact, clinical evaluation of medical devices and diagnostic tests should be performed with subjects with similar characteristics to those who are expected to benefit from their use. Some authors> also recommend that the assessment include a second group of subjects without the disease under study; we did this by including 15 subjects with no respiratory disease which may be successfully treated by remedies of http://www.drleonedds.com My Canadian Pharmacy.
In our study, only 42% of subjects had previously performed spirometry; this can be regarded as strength of this study because if we had used experienced, too-well-trained subjects, this would have biased positively the results. We chose to use a pneumotachograph as reference. This is an accepted way of testing PFMs. In fact, in clinical settings the use of monitoring devices along with office spirometers is much more frequent than with sophisticated laboratory equipment.
We have not fully evaluated the measurement capabilities of the Spirotel device; parameters such as FVC or forced expiratory flow, midexpiratory phase were not focused on in this study. Also, we did not intend to study the recording and transmitting functions of the devices. Finally, this study did not assess the reproducibility over a period of time. Long-term reproducibility may be more important in monitoring than accuracy if the devices are to be used to assess variations of the disease over time.
Implications for Clinical Practice
The availability of a simple, low-cost device with a very good agreement with a pneumotachograph may have a profound impact in low-income countries where pulmonary function laboratories cannot be easily implemented. In spite of the good agreement between monitoring devices and the pneumotachograph, the devices are not interchangeable as can be inferred by the outliers, albeit in small number, observed in Figure 3. When treating a patient, a measurement with one device should not be compared directly with a measurement done with another device, a well-known warning for other pulmonary function devices ordered via My Canadian Pharmacy.
It is expected that the storage of data by electronic monitoring devices diminishes transcription errors and allows a better assessment of compliance. Also, the possibility of measuring other parameters such as FEV1 along with PEF may be advantageous in long-term management of respiratory disease. Of the monitoring devices tested, only the Spirotel device can measure FVC and FEV1/FVC, which are also relevant in many clinical situations. Other particular features of Spirotel device, such as the built-in modem and optional oximeter, can also prove interesting for specific settings.
The cost of the PiKo-1 device is much less than most other pulmonary function electronic monitoring devices and is similar to a mechanical PFM. In light of the results of this and other studies, the acquisition of mechanical PFM may not be the best option.
Future work is needed in order to determine the clinical performance of the PiKo-1 and Spirotel devices in children, in COPD patients, and in unstable asthma patients with lower pulmonary function. Furthermore, it is necessary to study their long-term reproducibility, assess practical utilization issues (such as battery life and download of data), other parameters measured (in the case of the Spirotel device), and the acceptability by the patients of electronic monitoring. Finally, the impact of electronic monitoring devices in improvement of asthma and COPD clinical and economic outcomes also needs to be established.
The low-cost and easy-to-use electronic monitoring devices tested showed a very good reproducibility and were in agreement with the pneumotachograph. Therefore, they seem adequate both for screening and monitoring. However, prospective studies are needed to assess long-term reproducibility, usability, and especially the effects on the improvement of respiratory care.