Journal of clinical monitoring and computing
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J Clin Monit Comput · Apr 2012
Comparative StudyNon-invasive estimation of jugular venous oxygen saturation: a comparison between near infrared spectroscopy and transcutaneous venous oximetry.
The ability of practitioners to assess the adequacy of global oxygen delivery is dependent on an accurate measurement of central venous saturation. Traditional techniques require the placement of invasive central venous access devices. This study aimed to compare two non-invasive technologies for the estimation of regional venous saturation (reflectance plethysmography and near infrared spectroscopy [NIRS]), using venous blood gas analysis as gold standard. ⋯ In the NIRS group the mean biases were 10.8% and 2.0% for the sensors attached over the cerebral hemisphere and over the internal jugular vein, respectively, and the limits of agreement were 33.1 to -11.4 and 19.5 to -15.5% (r(2) = 0.22, 0.28;p = 0.04, 0.03) for the cerebral hemisphere and internal jugular sites, respectively. While transcutaneous regional oximetry and NIRS have both been used to estimate venous and tissue oxygen saturation non-invasively, the correlation between estimates of ScvO(2) and SxvO(2) were statistically significant for near infrared spectroscopy, but not for transcutaneous regional oximetry. Placement of cerebral oximetry patches directly over the internal jugular vein (as opposed to on the forehead) appeared to approximate internal jugular venous saturation better (lower mean bias and tighter limits of agreement), which suggests this modality may with refinement offer the practitioner additional clinically useful information regarding global cerebral oxygen supply and demand matching.
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J Clin Monit Comput · Apr 2012
Comparative StudyComparison of cardiac output determined by bioimpedance and bioreactance methods at rest and during exercise.
Bioreactance is a novel non-invasive method for cardiac output measurement that involves the analysis of blood flow-dependent changes in the phase shifts of electrical currents applied across the chest. The present study (1) compared resting and exercise cardiac outputs determined by bioreactance and bioimpedance methods and those estimated from measured oxygen consumption, (2) determined the relationship between cardiac output and oxygen consumption, and (3) assessed the agreement between the bioreactance and bioimpedance methods. Twelve healthy subjects (aged 30 ± 4 years) performed graded cardiopulmonary exercise test on a recumbent cycle ergometer on two occasions, 1 week apart. ⋯ Bland-Altman analyses including data from rest and exercise demonstrated that the bioimpedance method reported ~1.5 l min(-1) lower cardiac output than bioreactance with lower and upper limits of agreement of -2.98 to 5.98 l min(-1). Bioimpedance and bioreactance methods provide different cardiac output estimates, particularly at high exercise intensity, and therefore the two methods cannot be used interchangeably. In contrast with bioimpedance, bioreactance cardiac outputs are similar to those estimated from measured oxygen consumption.
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J Clin Monit Comput · Apr 2012
Peripherally inserted central catheters are equivalent to centrally inserted catheters in intensive care unit patients for central venous pressure monitoring.
To determine the equivalency of pressure measurements from peripherally inserted central catheters(PICCs) versus centrally inserted central venous catheters(CVCs) in vitro as well as in vivo. The in vitro study was performed in a clinical laboratory. Static pressure measurements from PICCs and CVCs were obtained in vitro over a physiologic range of 5–25 mmHg. ⋯ The paired CVP measurements were found to be highly reliable across subjects (r = 0.99, P<0.0001). No significance in the average difference in CVP measurement (PICC–CVC) was determined by the Wilcoxon Signed Rank test (S = 1,P = 0.93). In conclusion, PICCs are equivalent to CVCs when measuring static and dynamic pressure in vitro and CVP in ICU patients.
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J Clin Monit Comput · Apr 2012
Comparative StudyArterial pressure waveform derived cardiac output FloTrac/Vigileo system (third generation software): comparison of two monitoring sites with the thermodilution cardiac output.
The present study was conducted to study the effect of monitoring site, radial or femoral, for arterial pressure waveform derived cardiac output using FloTrac/Vigileo system with third generation software version 3.02 during cardiac surgery. The cardiac output derived from the two sites was also compared to the pulmonary artery catheter (PAC) derived cardiac output to reevaluate the relation between them using the newer software. The effect of cardiopulmonary bypass (CPB) was also studied by doing the sub analysis before and after bypass. ⋯ The post CPB precision of FEMCO was 1.2 times of PACCO while that of RADCO was 1.7 times of PACCO. The third generation of FloTrac/Vigileo system shows good correlation between the radial and femoral derived cardiac outputs in both pre and post bypass periods. The newer software correlates better to PAC derived cardiac output in the post bypass period for femoral artery than radial artery.
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J Clin Monit Comput · Apr 2012
Comparative StudyContinuous minimally invasive peri-operative monitoring of cardiac output by pulmonary capnotracking: comparison with thermodilution and transesophageal echocardiography.
A number of technologies are available for minimally-invasive cardiac output measurement in patients during surgery but remain little used. A system has been developed based on CO(2) elimination (VCO(2)) by the lungs for use in ventilated patients, which can be fully integrated into a modern anesthesia/monitoring platform, and provides semi-automated, continuous breath-by-breath cardiac output monitoring. A prototype measurement system was constructed to measure VCO(2) and end-tidal CO(2) concentration with each breath. ⋯ The method followed sudden changes in cardiac output due to arrythmias and run onto cardiopulmonary bypass in real time. The accuracy and precision were comparable to other clinical techniques. The method is relatively seamless and largely automated and has potential for continuous, cardiac output monitoring in ventilated patients during anesthesia and critical care.