Journal of clinical monitoring and computing
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J Clin Monit Comput · Jun 2012
Intraoperative MRI electrical noise and monitor ECG filters affect arrhythmia detection and identification.
Most electrical equipment in the modern operating room (OR) radiates electrical noise (EN) that can interfere with patient monitors. We have described the EN that an intraoperative magnetic resonance imaging (iMRI) system emits and have shown that this high-energy EN diminishes the quality of the ECG waveform during iMRI scans in our neurosurgical OR. We have also shown that the ECG signal filters in our iMRI-compatible patient monitor reduce this interference but, in the process, disturb the true morphology of the displayed waveform. ⋯ Depending on the OR design, the patient may be out of the anesthetist's direct view during a scan procedure. The anesthetist must rely on monitored physiologic parameters to assess patient status during this time. He/she should be familiar with his/her monitor's filtering capabilities and routinely adjust the ECG filters to achieve the best compromise between minimized EN effects and maximized displayed ECG signal quality.
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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 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 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.