Journal of clinical monitoring and computing
-
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.
-
J Clin Monit Comput · Feb 2015
Analysis of heart rate variability during auditory stimulation periods in patients with schizophrenia.
The vulnerability-stress model is a hypothesis for symptom development in schizophrenia patients who are generally characterized by cardiac autonomic dysfunction. Therefore, measures of heart rate variability (HRV) have been widely used in schizophrenics for assessing altered cardiac autonomic regulations. The goal of this study was to analyze HRV of schizophrenia patients and healthy control subjects with exposure to auditory stimuli. ⋯ In comparison with control subjects, patients with schizophrenia exhibited lower high-frequency power and a higher low-frequency to high-frequency ratio. Moreover, while WN stimulus decreased parasympathetic activity in healthy subjects, no significant changes in heart rate and frequency-domain HRV parameters were observed between the auditory stimulation and rest periods in schizophrenia patients. We can conclude that HRV can be used as a sensitive index of emotion-related sympathetic activity in schizophrenia patients.
-
J Clin Monit Comput · Feb 2015
Morphological analysis of peripheral arterial signals in Takayasu's arteritis.
Takayasu's arteritis disease (TA) remains a rarely studied chronic inflammatory disease. Our objective is to analyze peripheral pulse using photoplethysmography (PPG) as a new assessment method for diagnosing TA. So far no literature reports detailed morphological analysis of TA PPG signals. ⋯ Morphological parameters based classification method has sensitivity of 80-100 and specificity of 86-100 in all limbs/all parameters. Bilateral dissimilarity in morphological parameters of multi site peripheral signals in the TA patients can be used to diagnose TA patients and find the pathological site. Less population is studied which reflects the rarity of the TA disease.
-
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.
-
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.