Journal of clinical monitoring and computing
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J Clin Monit Comput · Feb 2015
Observational StudyThe relative trending accuracy of noninvasive continuous hemoglobin monitoring during hemodialysis in critically ill patients.
The pulse CO-Oximeter (Radical-7; Masimo Corp., Irvine, CA) is a multi-wavelength spectrophotometric method for noninvasive continuous monitoring of hemoglobin (SpHb). Because evaluating the relative change in blood volume (ΔBV) is crucial to avoid hypovolemia and hypotension during hemodialysis, it would be of great clinical benefit if ΔBV could be estimated by measurement of SpHb during hemodialysis. The capability of the pulse CO-Oximeter to monitor ΔBV depends on the relative trending accuracy of SpHb. ⋯ Bland-Altman analysis also revealed good agreement between ΔBV(SpHb) and ΔBV(CL-Hct) (bias, -0.77%; precision, 3.41%). Polar plot analysis revealed good relative trending accuracy of SpHb with an angular bias of 4.1° and radial limits of agreement of 24.4° (upper) and -16.2° (lower). The results of the current study indicate that SpHb measurement with the pulse CO-Oximeter has good relative trending accuracy.
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J Clin Monit Comput · Feb 2015
Improvements in the application and reporting of advanced Bland-Altman methods of comparison.
Bland and Altman have developed a measure called "limits of agreement" to assess correspondence of two methods of clinical measurement. In many circumstances, comparisons are made using several paired measurements in each individual subject. If such measurements are considered as statistically independent pairs, rather than as sets of measurements from separate individuals, limits of agreement will be too narrow. ⋯ Therefore, we set out to provide a freely available implementation accompanied by a formal description of the more advanced Bland-Altman comparison methods. We validate the implementation using simulated data, and demonstrate the effects caused by failing to take the presence of multiple paired measurements per individual properly into account. We propose a standard format of reporting that would improve analysis and interpretation of comparison studies.
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J Clin Monit Comput · Feb 2015
Accuracy of bedside glucometry in critically ill children with peripheral hypoperfusion.
The accuracy of glucose test strip in critically care has been questioned. We investigated the accuracy of glucose test strip in critically ill children. Patients, aged from 1 month to 18 years admitted in pediatric intensive care unit. ⋯ The CBG test strip must be interpreted carefully in critically ill children. A low PI was associated with poor CBG strip accuracy. WBG test strip from arterial blood was more appropriate for glucose monitoring in children with peripheral hypoperfusion.
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J Clin Monit Comput · Feb 2015
Case ReportsRepeated early hemofiltration filters clotting and heparin-induced thrombocytopenia in ICU.
Repeated early hemofiltration filter clotting are real thrombotic events. Diagnosis of heparin-induced thrombocytopenia (HIT) in this setting in ICU remains difficult. ⋯ Despite a 4T's score of three for the two patients and persistent early hemofiltration clotting filters, functional tests for HIT antibodies (heparin induced platelet activation assay and serotonin release assay) were positive, permitting the diagnosis of HIT in both patients. We suggest that the occurrence of repeated, rapid (within 6 h) hemofiltration filter clotting should score as two points for "Thrombosis" in the 4T's scoring system, thereby increasing the pretest probability for HIT in this clinical situation.
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J Clin Monit Comput · Feb 2015
Thoracic impedance measures tissue characteristics in the vicinity of the electrodes, not intervening lung water: implications for heart failure monitoring.
The rationale for intrathoracic impedance (Z) detection of worsening heart failure (HF) presupposes that changes in Z reflect changes in pulmonary congestion, but is confounded by poor specificity in clinical trials. We therefore tested the hypothesis that Z is primarily affected by tissue/water content in proximity to electrodes rather than by lung water distribution between electrodes through the use of a new computational model for deriving the near-field impedance contributions from the various electrodes. Six sheep were implanted with a left atrial pressure (LAP) monitor and a cardiac resynchronization therapy device which measured Z from six vectors comprising of five electrodes. ⋯ In contrast, during the simulated formation of device-pocket edema (induced by fluid injection) the near-field impedance of the subcutaneous electrode had an instantaneous response, while the intra-cardiac electrodes had a minimal inconsistent response. This study suggests that the primary contribution to the vector based Z is from the tissue/water in proximity to the individual electrodes. This novel finding may help explain the limited utility of Z for detecting worsening HF.