Journal of clinical monitoring and computing
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J Clin Monit Comput · Aug 2017
Reliability of cardiac output measurements using LiDCOrapid™ and FloTrac/Vigileo™ across broad ranges of cardiac output values.
Knowing a patient's cardiac output (CO) could contribute to a safe, optimized hemodynamic control during surgery. Precise CO measurements can serve as a guide for resuscitation therapy, catecholamine use, differential diagnosis, and intervention during a hemodynamic crisis. Despite its invasiveness and intermittent nature, the thermodilution technique via a pulmonary artery catheter (PAC) remains the clinical gold standard for CO measurements. ⋯ An F test revealed no significant difference in the widths of the LoA for both devices when sample sizes capable of detecting a more than two-fold difference were used. We found that both devices tended to underestimate the calculated CIs when the CIs were relatively high. These proportional bias produced large percentage errors in the present study.
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J Clin Monit Comput · Aug 2017
Gradient adjustment method for better discriminating correlating and non-correlating regions of physiological signals: application to the partitioning of impaired and intact zones of cerebral autoregulation.
Cerebral blood flow (CBF) is regulated over a range of systemic blood pressures by the cerebral autoregulation (CA) control mechanism. This range lies within the lower and upper limits of autoregulation (LLA, ULA), beyond which blood pressure drives CBF, and CA function is considered impaired. A standard method to determine autoregulation limits noninvasively using NIRS technology is via the COx measure: a moving correlation index between mean arterial pressure and regional oxygen saturation. ⋯ It is shown that the derived GACOx indices exhibit a mean difference between the intact/impaired regions of 1.54 ± 0.26 (mean ± SD), compared to 0.14 ± 0.10 for the traditional COx method. The GACOx effectively polarizes the COx data in order to better differentiate the intact and impaired zones and, in doing so, makes the determination of the LLA and ULA points a simpler and more consistent task. The method lends itself to the automation of the robust determination of autoregulation zone limits.
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Understanding the use of patient monitoring systems in emergency and acute facilities may help to identify reasons for failure to identify risk patients in these settings. Hence, we investigate factors related to the utilization of automated monitoring for patients admitted to an acute admission unit by introducing monitor load as the proportion between monitored time and length of stay. A cohort study of patients admitted and registered to patient monitors in the period from 10/10/2013 to 1/10/2014 at the acute admission unit of Odense University Hospital in Denmark. ⋯ Higher levels of severity were related to higher degrees of monitoring, but being admitted to the surgical wing reduce how much patients were monitored, and periods with many concurrent patients lead to a small increase in monitoring. We found a significant variation concerning how much patients were monitored during admission to an acute admission unit. Our results point to potential patient safety improvements in clinical procedures, and advocate an awareness of how patient monitoring systems are utilized.
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J Clin Monit Comput · Jun 2017
Comparative Study Observational StudyEffect of patent ductus arteriosus and patent foramen ovale on left ventricular stroke volume measurement by electrical velocimetry in comparison to transthoracic echocardiography in neonates.
This prospective single-center observational study compared impedance cardiography [electrical velocimetry (EV)] with transthoracic echocardiography (TTE, based on trans-aortic flow) and analyzed the influence of physiological shunts, such as patent ductus arteriosus (PDA) or patent foramen ovale (PFO), on measurement accuracy. Two hundred and ninety-one triplicate simultaneous paired left ventricular stroke volume (LVSV) measurements by EV (LVSVEV) and TTE (LVSVTTE) in 99 spontaneously breathing neonates (mean weight 3270 g; range 1227-4600 g) were included. For the whole cohort, the mean absolute LVSVEVwas 5.5 mL, mean LVSVTTEwas 4.9 mL, resulting in an absolute Bland-Altman bias of -0.7 mL (limits of agreement LOA -3.0 to 1.7 mL), relative bias -12.8 %; mean percentage error MPE 44.9 %; true precision TPEV33.4 % (n = 99 aggregated data points). ⋯ In neonates with shunts (PDA and/or PFO; n = 67): mean LVSVEV5.8 mL, mean LVSVTTE5.0 mL, bias -0.8 mL (LOA -3.1 to 1.5 mL), relative bias -14.8 %, MPE 41.9 %, TPEV29.3 %. Accuracy was affected by PDA and/or PFO, with a significant increase in the relative difference in LVSVEVversus LVSVTTE: Subjects without shunts -2.9 % (n = 91), PFO alone -9.6 % (n = 125), PDA alone -14.0 % (n = 12), and PDA and PFO -18.5 % (n = 63). Physiological shunts (PDA and/or PFO) in neonates affect measurement accuracy and cause overestimation of LVSVEVcompared with LVSVTTE.