Journal of clinical monitoring and computing
-
J Clin Monit Comput · Aug 2008
Non-invasive automated measurement of cardiac output during stable cardiac surgery using a fully integrated differential CO(2) Fick method.
To re-evaluate the accuracy and precision of a non-invasive method for measurement of cardiac output based on the differential CO(2) Fick approach using an automated change in respiratory rate delivered by a ventilator under control by a prototype measurement system. ⋯ Acceptable agreement with thermo- dilution during surgery was found, particularly where the ventilatory change involved an increase in respiratory rate from a lower baseline. This approach has potential to be readily integrated into modern anesthesia delivery platforms, allowing routine non-invasive cardiac output measurement.
-
J Clin Monit Comput · Aug 2008
Comparative StudyContinuous, non-invasive techniques to determine cardiac output in children after cardiac surgery: evaluation of transesophageal Doppler and electric velocimetry.
Continuous and non-invasive measurement of cardiac output (CO) may contribute helpful information to the care and treatment of the critically ill pediatric patient. Different methods are available but their clinical verification is still a major problem. ⋯ In pediatric patients non-invasive measurement of CO and SV with TED and EV is useful for continuous monitoring after heart surgery. Both new methods seem to underestimate cardiac output in terms of absolute values. However, TED shows tolerable bias and precision and may be helpful for continuous CO monitoring in a deeply sedated and ventilated pediatric patient, e.g. in the operating room or intensive care unit.
-
J Clin Monit Comput · Aug 2008
A measure of confidence in Bland-Altman analysis for the interchangeability of two methods of measurement.
Bland-Altman (B-A) analysis has largely replaced the correlation coefficient as the predominant tool for evaluating the interchangeability of two methods of clinical measurement. However, we contend that B-A analysis might lead to erroneous conclusions when the data range is small. We provide an example to illustrate this and explore a possible analysis technique to address this limitation.
-
J Clin Monit Comput · Aug 2008
Noninvasive detection of the hemodynamic stress of exercise using the photoplethysmogram.
Exercise induced hemodynamic stress has been studied extensively using a wide range of physiological sensors. While athletes can modulate their training intensity using EKG-based heart rate monitors, there are currently no noninvasive monitors that can be used to ascertain with a high degree of certainty the hemodynamic stress an individual is experiencing because of fatigue or an underlying pathology. We propose that cardiac stress will result in detectable changes in skin blood flow. ⋯ As volitional fatigue approached, the low frequency (f = 0.05-0.2 Hz) amplitude modulation observed in the PPG became more pronounced; then, within several seconds of the cessa- tion of the protocol, they disappeared. Using a software-based detector, these distinct waves are reliably detected, with a low incidence of false positives, in all subjects before the onset of volitional fatigue. We hypothesize that the low frequency waves observed in the PPG of individuals exercising to volitional fatigue provide a mechanism for noninvasively detecting hemodynamic stress to the human vascular system.
-
J Clin Monit Comput · Jun 2008
The sound intensity and characteristics of variable-pitch pulse oximeters.
Various studies worldwide have found that sound levels in hospitals significantly exceed the World Health Organization (WHO) guidelines, and that this noise is associated with audible signals from various medical devices. The pulse oximeter is now widely used in health care; however the health effects associated with the noise from this equipment remain largely unclarified. Here, we analyzed the sounds of variable-pitch pulse oximeters, and discussed the possible associated risk of sleep disturbance, annoyance, and hearing loss. ⋯ The results indicate that sounds from pulse oximeters pose a potential risk of not only sleep disturbance and annoyance but also hearing loss, and that these sounds are unnatural for human auditory perception.