Physiological measurement
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Physiological measurement · Feb 2012
Clinical TrialEffects of awareness and nociception on heart rate variability during general anaesthesia.
During anaesthesia awareness and nociception are serious complications that may further lead to haemodynamic instability. Specific monitoring of depth of hypnosis and depth of analgesia based on heart rate variability (HRV) analysis is eligible to improve patient safety and reduce efforts in post-operative care. Consequently, in this analysis we assess the applicability of HRV parameters during surgical interventions with standardized intravenous propofol-remifentanil-anaesthesia. ⋯ While standard time-domain parameters lacked selectivity, parameters of symbolic dynamics appear to be specifically influenced by changes in depth of hypnosis and nociception, respectively. However, the lack of steady-state ventilation/breathing in this study needs to be considered in future research. To be used for clinical anaesthesia monitoring our results have to be prospectively validated in clinical studies.
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Physiological measurement · Jan 2012
Comparative StudyDetermination of blood volume by pulse CO-oximetry.
The objective of this study was to determine whether changes in carboxyhaemoglobin (COHb) saturation following carbon monoxide (CO) rebreathing can be accurately detected by pulse CO-oximetry in order to determine blood volume. Noninvasive measurements of carboxyhaemoglobin saturation (SpCO) were continuously monitored by pulse CO-oximetry before, during and following 2 min of CO rebreathing. ⋯ Changes in COHb saturation and SpCO following CO rebreathing were strongly correlated (r = 0.90, p < 0.01), resulting in a significant correlation between invasive and noninvasive blood volume measurements (r = 0.83, p = 0.02). Changes in SpCO following CO rebreathing can be accurately detected by pulse CO-oximetry, which could potentially provide a simplified, convenient and reproducible method to rapidly determine blood volume in healthy individuals.
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Physiological measurement · Jan 2012
Regional cerebral oxygen saturation in newborn infants in the first 15 min of life after vaginal delivery.
The objective of this study was to evaluate regional oxygen saturation of the brain during immediate transition after birth, and to correlate it with pre-ductal arterial oxygen saturation in newborn infants. The prospective observational study including newborn infants in the first 15 min after spontaneous vaginal delivery and uncomplicated transitional period was undertaken. Regional cerebral oxygen saturation (rSO(2)brain) was measured using near-infrared spectroscopy. ⋯ Of 145 newborn infants, 16 were included and the gender allocation was 31 females (49.2%) and 32 males (50.8%). rSO(2)brain increased rapidly from 39% (2 min) to 69% (5 min), SpO(2) increased from 72% (2 min) to 96% (14 min) and FTOE showed a significant decrease from minute 2 (0.47) until minute 4 (0.30) and an increase between 8 to 13 min. rSO(2)brain increased rapidly after vaginal delivery. Although SpO(2) increased within the first 14 min after delivery, rSO(2)brain showed no further significant changes after 5 min. FTOE decreased in the first 4 min and reached standard values subsequently.
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Physiological measurement · Jan 2012
Psychophysical parameters of a multidimensional pain scale in newborns.
The Premature Infant Pain Profile (PIPP) is a promising multidimensional tool for comparison and testing of new technologies in newborn pain assessment studies since it may adhere to basic psychophysical parameters of intensity, direction, reactivity, regulation and slope described in analyses of physiological pain indicators. The aim of this study was to evaluate whether these psychophysical parameters can be achieved using the PIPP in acute pain assessment. Thirty-six healthy term newborn infants were conveniently sampled whilst being videotaped before, during and after heel prick blood sampling. ⋯ The oxygen saturation variability met only the intensity parameter (p < 0.05). The behavioural state indicator met all parameters and had the best correlation to the psychophysical parameters of all indicators of PIPP (all p < 0.001). We concluded that the overall PIPP meets the assumptions of these psychophysical parameters, being the behavioural state indicator which best fit the model.
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Physiological measurement · Dec 2011
Patient examinations using electrical impedance tomography--sources of interference in the intensive care unit.
Electrical impedance tomography (EIT) is expected to become a valuable tool for monitoring mechanically ventilated patients due to its ability to continuously assess regional lung ventilation and aeration. Several sources of interference with EIT examinations exist in intensive care units (ICU). Our objectives are to demonstrate how some medical nursing and monitoring devices interfere with EIT measurements and modify the EIT scans and waveforms, which approaches can be applied to minimize these effects and how possible misinterpretation can be avoided. ⋯ Discontinuation of pulsation therapy and of continuous cardiac output and impedance respiration monitoring immediately improved the EIT signal and scan quality. Offline processing of the disturbed data using frequency filtering enabled partial retrieval of relevant information. We conclude that thoracic EIT examinations in the ICU require cautious interpretation because of possible mechanical and electromagnetic interference.