Journal of clinical monitoring and computing
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J Clin Monit Comput · Jun 2013
Randomized Controlled TrialComposite-, plain-auditory evoked potentials index and bispectral index to measure the effects of sevoflurane.
The composite auditory evoked potentials index (cAAI) uses both cortical electroencephalogram (EEG) and response to auditory stimuli, while the bispectral index (BIS) uses only the cortical EEG and auditory evoked potentials index (AAI) uses only response to auditory stimuli. We expected that the cAAI was more useful to monitor anesthetic effect of sevoflurane than the BIS and AAI. The present study compared the changes of cAAI, AAI, and BIS in different sevoflurane concentration. ⋯ The cAAI had the largest and AAI had the smallest inter-individual variation. In sevoflurane-nitrous oxide anesthesia, cAAI was inferior to AAI and BIS to discriminate different anesthetic effect. The cAAI had larger inter-individual variation than the AAI and BIS.
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A new application of photoplethysmography (PPG) has emerged recently to provide the possibility of heart rate monitoring without a telemetric chest strap. The aim of this study was to determine if a new device could detect pulsation over a broad range of skin types, and what light wavelength would be most suitable for detecting the signals. A light emitting diode-based PPG system was used to detect changes in pulsatile blood flow on 23 apparently healthy individuals (11 male and 12 female, 20-59 years old) of varying skin types classified according to a questionnaire in combination with digital photographs with a skin type chart. Four different light wavelengths (470, 520, 630, and 880 nm) were tested. Normalized modulation level is calculated as the AC/DC component ratio and represents the change in flow over the underlying constant state of flow or perfusion. ⋯ We concluded that a PPG-based device can detect pulsation across all skin types and that a greater resolution was obtained using a green light wavelength at rest and a green or blue light wavelength during exercise.
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J Clin Monit Comput · Jun 2013
Randomized Controlled TrialStO₂ guided early resuscitation in subjects with severe sepsis or septic shock: a pilot randomised trial.
The scientific community has agreed upon developing accurate monitoring of tissue perfusion and oxygenation to improve the management of subjects with sepsis. This pilot study aimed to investigate the feasibility of targeting tissue oxygen saturation (StO₂) in addition to the currently recommended resuscitation goals, central venous pressure, mean arterial pressure and central venous oxygen saturation, in patients with severe sepsis or septic shock. A pilot, single-centre, randomised, non-blinded trial recruited 30 subjects with severe sepsis upon intensive care unit admission at an academic medical centre in France. ⋯ At study day 7, there were 5/15 (33.3 %) subjects who died or had a DSOFA > 0 in the experimental arm and 4/15 (26.6 %) who died or had a DSOFA > 0 in the control arm (p = 1.00). This pilot study was the first randomised controlled trial using an algorithm derived from the SSC recommendations, which included StO₂ as a treatment goal. However, the protocol showed no clear trend for or against targeting StO₂.
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J Clin Monit Comput · Jun 2013
A system for portable sleep apnea diagnosis using an embedded data capturing module.
Sleep apnea (SA) is a very common disease with serious health consequences, yet is very under-diagnosed, partially because of the high cost and limited accessibility of in-laboratory polysomnography (PSG). The purpose of this work is to introduce a newly developed portable system for the diagnosis of SA at home that is both reliable and easy to use. The system includes personal devices for recording breath sounds and airflow during sleep and diagnostic algorithms to process the recorded data. The data capturing device consists of a wearable face frame with an embedded electronic module featuring a unidirectional microphone, a differential microphone preamplifier, a microcontroller with an onboard differential analogue to digital converter, and a microSD memory card. The device provides continuous data capturing for 8 h. Upon completion of the recording session, the memory card is returned to a location for acoustic analysis. We recruited 49 subjects who used the device independently at home, after which each subject answered a usability questionnaire. Random data samples were selected to measure the signal-to-noise ratio (SNR) as a gauge of hardware functionality. A subset of 11 subjects used the device on 2 different nights and their results were compared to examine diagnostic reproducibility. Independent of those, system's performance was evaluated against PSG in the lab environment in 32 subject. The overall success rate of applying the device in un-attended settings was 94 % and the overall rating for ease-of-use was 'excellent'. Signal examination showed excellent capturing of breath sounds with an average SNR of 31.7 dB. Nine of the 11 (82 %) subjects had equivalent results on both nights, which is consistent with reported inter-night variability. The system showed 96 % correlation with simultaneously performed in-lab PSG. ⋯ Our results suggest excellent usability and performance of this system and provide a strong rationale to further improve it and test its robustness in a larger study.
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J Clin Monit Comput · Jun 2013
Clinical TrialThe analysis of transesophageal oxygen saturation photoplethysmography from different signal sources.
The photoplethysmography (PPG) signals detected by transesophageal oximetry sensor toward aorta arch (AA), descending aorta (DA), and left ventricle (LV) under the guidance of transesophageal echocardiography (TEE) were investigated, and the effects of filter application on PPG signals were evaluated. Eleven cardiac surgical patients were involved. After anesthesia was induced, the TEE probe with a modified pulse oximetry sensor was inserted. ⋯ The AC amplitude in LV PPG was significant larger than in AA and DA PPG, and both AC/DC and ventilation-induced AC variation in LV PPG were significantly higher than in AA PPG or DA PPG either. There were no significant differences of AC amplitude between filtered and ventilation off PPG signals. The AC amplitudes and AC/DC toward LV are significantly higher than transesophageal oximeter toward AA or DA, and the effect of mechanical ventilation on transesophageal PPG can be obviously reduced by filtering techniques.