Continuous Noninvasive Measurement of Pulsus Paradoxus Complements Medical Decision Making in Assessment of Acute Asthma Severity: Limitations
In reality, the complexities of optical plethysmography, along with their inherent noise, may preclude the utility of a simple relationship in a pulse oximeter that also displays PP. Filtering and straightforward signal-processing methods like least mean squares approximation and best uniform approximation will be needed to take this next step.
Expert systems have appeared in many areas of health care. Examples include the bispectral index monitor, which gauges the depth of general anesthesia or conscious sedation, and the time-insensitive predictive instrument score, which measures the shape and elevation of the ST segment on 12-lead ECGs. These tools are especially useful in the context of emergency medicine by objectifying a subjective clinical assessment and reassessing a preconceived probability. An instrument like a PP monitor could serve as a patient management decision aid or in the detection of cardiopulmonary dyscrasias. buy zoloft online
The noninvasive continuous BP monitors used in this study measured BP to an acceptable degree of precision but tended to overestimate BP in the case of one monitor (FINAPRES; Ohmeda). However, the absolute difference in SBP between expiration and inspiration was calculated, which diminishes the significance of errors in the absolute values of BP. Continuous noninvasive BP monitors are not widely available clinically, which limits the ability to immediately deploy algorithms that calculate PP. In addition, arterial tonometry in this study was unable to acquire a continuous BP recording in 10% of patients due to motion artifacts or large wrist girth. Oscillometric BP monitors are unsuitable for this application as they do not provide a continuous measure of BP.
Some patients arriving at the hospital by ambulance were partially treated on study enrollment, which may have affected the analysis of the AT-PP ROC during the pretreatment phase. This could also have affected the posttreatment calculations as well, since these patients would have received larger amounts of inhaled (3-agonist agents than those patients arriving at the hospital by other means. However, this possibility is minimized by the fact that only 17% of patients arrived by ambulance, and in each case only one treatment was delivered prior to ED arrival. In addition, the main findings of this report remain clinically relevant as disposition is generally determined after standardized treatment is completed, which typically mirrors the NAEPP guidelines but may not be strictly adherent. Finally, physicians and raters were not held constant in keeping with clinical reality, thus warranting the calculation of intraclass correlation in lieu of interrater reliability.