Journal of clinical monitoring and computing
-
J Clin Monit Comput · Dec 2012
Case ReportsAdditional hemodynamic measurements with an esophageal Doppler monitor: a preliminary report of compliance, force, kinetic energy, and afterload in the clinical setting.
The esophageal Doppler monitor (EDM) is a minimally-invasive hemodynamic device which evaluates both cardiac output (CO), and fluid status, by estimating stroke volume (SV) and calculating heart rate (HR). The measurement of these parameters is based upon a continuous and accurate approximation of distal thoracic aortic blood flow. Furthermore, the peak velocity (PV) and mean acceleration (MA), of aortic blood flow at this anatomic location, are also determined by the EDM. ⋯ When normalized to each of their initial values, F and KE both consistently demonstrated more discriminative power than either PV or MA. The EDM offers additional applications for hemodynamic monitoring. Further research regarding the accuracy, utility, and limitations of these parameters is therefore indicated.
-
J Clin Monit Comput · Dec 2012
Combination of continuous pulse pressure variation monitoring and cardiac filling pressure to predict fluid responsiveness.
To assess if combining central venous pressure (CVP) and/or pulmonary capillary wedge pressure (PCWP) information with arterial pulse pressure variation can increase the ability to predict fluid responsiveness in patients under general anesthesia. This study is a retrospective analysis of patients scheduled for coronary artery bypass surgery and monitored with a pulmonary artery catheter who underwent a volume expansion after induction of general anesthesia. Among the 46 patients studied, 31 were responders to volume expansion. ⋯ Combining information on right and/or left cardiac filling pressures with PPV did not increase the ability to predict whether a patient will be a responder or a non-responder to volume expansion. The ability to identify a potentially fluid responsive patient was no better using PPV plus cardiac filling pressures when compared to using PPV alone. Therefore, if PPV values are being monitored in a patient, CVP and PCWP values do not provide additional information to predict fluid responsiveness.
-
J Clin Monit Comput · Oct 2012
Radial-femoral concordance in time and frequency domain-based estimates of systemic arterial respiratory variation.
Commonly used arterial respiratory variation metrics are based on mathematical analysis of arterial waveforms in the time domain. Because the shape of the arterial waveform is dependent on the site at which it is measured, we hypothesized that analysis of the arterial waveform in the frequency domain might provide a relatively site-independent means of measuring arterial respiratory variation. Radial and femoral arterial blood pressures were measured in nineteen patients undergoing liver transplantation. ⋯ Assuming a PPV treatment threshold of 12 % (or equivalent), differences in treatment decisions based on radial or femoral estimates would arise in 12, 14, 5.4, 5.7, 4.8, and 5.5 % of minutes for SPV, PPV, AUCV, MAPV, spectral peak ratio, and spectral power ratio, respectively. As compared to frequency domain-based estimates of respiratory variation, SPV and PPV are relatively dependent on the anatomic site at which they are measured. Spectral peak and power ratios are relatively site-independent means of measuring respiratory variation, and may offer a useful alternative to time domain-based techniques.
-
The pulmonary artery catheter (PAC) has been widely used for monitoring of critically ill patients over the years, but with advances in less invasive monitoring techniques, notably echocardiography, there are fewer indications for PAC insertion. Nevertheless, the PAC provides simultaneous monitoring of pulmonary artery pressures, cardiac filling, cardiac output and mixed venous oxygen saturation, and still has an important role in complex cases. Adequate and continued training are required to ensure that PAC-derived data are correctly interpreted and applied.