Journal of clinical monitoring and computing
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J Clin Monit Comput · Apr 2014
Improved spatial resolution and electrogram wave direction independence with the use of an orthogonal electrode configuration.
To improve spatial resolution in recordings of intra-cardiac electrograms we characterized the utility of a novel configuration of two recording electrodes arranged perpendicularly to the endocardial surface. We hypothesized that this configuration denoted as orthogonal close unipolar (OCU) would combine advantages of conventional unipolar and contact bipolar (CBP) configurations. Electrical excitation was simulated in a computational model as arising from dipole current or from multi-wavelet reentry sources. ⋯ The difference between the actual dominant frequency in the tissue and that recorded by the electrodes was 0.44 ± 0.33 Hz for OCU, 0.58 ± 0.40 Hz for unipolar, and 0.62 ± 0.46 Hz for CBP. OCU confers improved spatial resolution compared with both unipolar and CBP electrode configurations. Unlike the case with CBP, OCU recordings are independent of excitation wave-front direction.
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J Clin Monit Comput · Apr 2014
Comparative StudyEvaluation of point-of-care analyzers' ability to reduce bias in conductivity-based hematocrit measurement during cardiopulmonary bypass.
Most point-of-care testing analyzers use the conductivity method to measure hematocrit (hct). During open-heart surgery, blood-conductivity is influenced by shifts in electrolyte and colloid concentrations caused by infusion media used, and this may lead to considerable bias in the hct measurement. We evaluated to what extent different analyzers correcting for 0, 1, 2, or 3 factors, respectively, compensated for this electrolyte/colloid interference: (1) the conductivity method with no correction (IRMA), (2) with a [Na(+)]-correction (GEM Premier 3000), (3) with a [Na(+)]/[K(+)]-correction (i-STAT), and (4) with a [Na(+)]/[K(+)]-correction in combination with an algorithm that estimates the protein dilution [i-STAT in cardiopulmonary bypass (CPB)-mode]. ⋯ In order of high to low electrolyte/colloid interference: the analyzer with no correction, [Na(+)]-correction, [Na(+)/]/[K(+)]-correction, and [Na(+)/]/[K(+)]/estimated protein-correction showed a change of bias from stage I to stage III of -3.9 ± 0.5, -3.4 ± 0.4, -2.1 ± 0.5, -0.3 ± 0.5%. We conclude that correcting for more parameters (Na(+), K(+), estimated protein) gives less bias, but residual bias remains even after [Na(+)/]/[K(+)]/estimated protein-correction. This suggests that a satisfactory algorithm should also correct for other colloidal factors than protein.
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J Clin Monit Comput · Apr 2014
Controlled Clinical TrialEntropy correlates with Richmond Agitation Sedation Scale in mechanically ventilated critically ill patients.
Sedation is routinely used in intensive care units. However due to absence of objective scoring systems like Bispectral Index and entropy our ability to regulate the degree of sedation is limited. This deficiency is further highlighted by the fact that agitation scores used in intensive care units (ICU) have no role in paralyzed patients. ⋯ There was a statistically significant correlation between the state entropy (SE) and RASS [Spearman's rho/rs = 0.334, p\0.0001]; response entropy (RE) and RASS [Spearman's rho/rs = 0.341, p\0.0001]). For adequate sedation as judged by a RASS value of 0 to -3, the mean SE was 57.86 ± 16.50 and RE was 67.75 ± 15.65. The present study illustrates that entropy correlates with RASS (between scores 0 and -3) when assessing the level of sedation in mechanically ventilated critically ill patients.
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J Clin Monit Comput · Apr 2014
A case of anastomosis malposition of the Blalock-Taussig shunt diagnosed using perioperative transesophageal echocardiography monitoring.
The perioperative transesophageal echocardiography (TEE) is a very useful and minimal invasive monitoring not only for the cardiac anesthesia management, but also for the anesthesia management of the non-cardiac operations of the heart high risk patients. In this case report, we report a case of the urgent Blalock-Taussig shunt (BT shunt) operation for a small patient of Fallot's tetralogy with anoxic spell, which showed an atypical change of hemodynamics and SpO2 with the shunt opening. After the BT shunt anastomosis, the diastolic blood pressure decreased with the shunt opening, however, the expected rise of SpO2 was not provided. By the perioperative TEE monitoring with the single plane TEE transducer for neonate; UST-52110S (Hitachi Aloka Medical, Tokyo, Japan) with 4.5 mm in diameter, the cause of this atypical change of hemodynamics and SpO2 was diagnosed to be an accidental anastomosis malposition of the BT shunt to the right pulmonary vein and reported to the operator during the operation, and the operation was performed correctly.
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J Clin Monit Comput · Apr 2014
A novel airway device with tactile sensing capabilities for verifying correct endotracheal tube placement.
We present a new device for verifying endotracheal tube (ETT) position that uses specialized sensors intended to distinguish anatomical features of the trachea and esophagus. This device has the potential to increase the safety of resuscitation, surgery, and mechanical ventilation and decrease the morbidity, mortality, and health care costs associated with esophageal intubation and unintended extubation by potentially improving the process and maintenance of endotracheal intubation. ⋯ It is intended to detect the presence or absence of tracheal rings immediately upon inflation of the airway occlusion cuff. The initial study detailed here verifies that a prototype device can detect contours similar to tracheal rings in a tracheal model.