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 StudyImpact of non invasive and beat-to-beat arterial pressure monitoring on intraoperative hemodynamic management.
The Nexfin device allows for non-invasive beat-to-beat blood pressure monitoring (BP(NXF)). Perioperative hypotension and hypertension have been shown to be associated with poor clinical outcomes. The goal of the present study was to assess the ability of this device to decrease the duration of significant intraoperative hypo- or hypertension compared to standard BP monitoring by cuff (BP(CUFF)). ⋯ If hemodynamic changes seen by SBP(NXF) were appropriately treated, an average of 7 ± 1 min/h of hypotension time, 7 ± 2 min/h of hypertension time and 14 ± 3 min per hour of hypo- or hypertension time may have been identified. The Nexfin BP has the potential to decrease the time of hypotension and hypertension compared to conventional intermittent BP(CUFF) monitoring. Therefore, this device has the potential to positively impact clinical outcomes.
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J Clin Monit Comput · Apr 2012
Comparative StudyPulse-plethysmographic variables in hemodynamic assessment during mannitol infusion.
Plethysmographic signal using pulse oximetry may be used to assess fluid status of patients during surgery as it resembles arterial pressure waveform. This will avoid placement of invasive arterial lines. This study was designed to find out whether intravascular volume changes induced by mannitol bolus in neurosurgical patients are detected by variations in arterial pressure and plethysmographic waveforms and also to assess the strength of correlation between different variables derived from these two waveforms. ⋯ The correlation between ∆SPV-∆Pl-PV, ∆PPV-∆Pl-AV and ∆SPV-∆BP-Pleth time lag were significant (r = 0.3; P < 0.01). SPV and time lag had no significant interaction. Pl-PV correlates well with SPV following mannitol infusion and can be used as an alternative to SPV. (BP-Pleth) time-lag promises to be an important parameter in assessing the state of peripheral vascular resistance and deserves further investigation.
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J Clin Monit Comput · Apr 2012
Comparative StudyNoninvasive continuous beat-to-beat radial artery pressure via TL-200 applanation tonometry.
The Tensys TL-200(®) noninvasive beat-to-beat blood pressure (BP) monitor displays continuous radial artery waveform as well as systolic, mean and diastolic BP from a pressure sensor directly over the radial artery at the wrist. It locates the site of maximal radial pulse signal, determines mean BP from maximal pulse waveform amplitude at optimal artery compression and then derives systolic and diastolic BP. We performed a cross-sectional study of TL-200 BP comparisons with contralateral invasive radial artery (A-Line) BP values in 19 subjects during an average 2.5 h of general anesthesia for a wide range of surgical procedures. ⋯ Coefficients of determination for TL-200 and A-Line BP regression were r² = 0.86 for systolic, r² = 0.86 for mean, and r² = 80 for diastolic BP, respectively, with no apparent change in correlation at low or high BP. Bland-Altman analysis suggested satisfactory agreement between TL-200 noninvasive beat-to-beat BP and invasive A-Line BP. Paired TL-200/A-Line BP comparisons showed a high coefficient of determination.
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J Clin Monit Comput · Apr 2012
Comparative StudyA comparative study of pulse rate variability and heart rate variability in healthy subjects.
Both heart rate variability (HRV) and pulse rate variability (PRV) are noninvasive means for the assessment of autonomic nervous control of the heart. However, it is not settled whether or not the PRV obtained from either hand can be the surrogate of HRV. The HRV measures obtained from electrocardiographic signals and the PRV measures obtained from the pulse waves recorded from the index fingers of both hands were compared in normal subjects by using linear regression analysis and Bland and Altman method. ⋯ The PRV of either hand is close to, but not the same as the HRV in healthy subjects. The HRV, right PRV and left PRV are not surrogates of one another in normal subjects except heart rate and ULFP. Since HRV is generally accepted as the standard method for the assessment of the autonomic nervous modulation of a subject, the PRV of either hand may not be suitable for the assessment of the cardiac autonomic nervous modulation of the subject.