Clinical physiology and functional imaging
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Clin Physiol Funct Imaging · Jul 2009
Heart rate variability during sleep and sleep apnoea in a population based study of 387 women.
Increased sympathetic activity during sleep has been suggested as a link between obstructive sleep apnoea syndrome and cardiovascular disease. Heart rate variability (HRV) is a measure of autonomic effect on the heart. Different parameters have been associated with sympathetic and parasympathetic activity. ⋯ In slow wave sleep the parameters decreased. In conclusion, moderately increased prevalence of obstructive apnoeas was associated with signs of higher sympathetic activity. High AHI was however associated with a HRV-pattern suggestive of depressed sympathetic drive and lowered ability to increase it during REM.
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Clin Physiol Funct Imaging · May 2009
Changes in left ventricular ejection time and pulse transit time derived from finger photoplethysmogram and electrocardiogram during moderate haemorrhage.
Early identification of haemorrhage is difficult when a bleeding site is not apparent. This study explored the potential use of the finger photoplethysmographic (PPG) waveform derived left ventricular ejection time (LVET(p)) and pulse transit time (PTT) for detecting blood loss, by using blood donation as a model of controlled mild to moderate haemorrhage. ⋯ Shortening of LVET(p) from 303+/-2 to 293+/-3 ms (mean+/-SEM; P<0.01) and prolongation of PTT from 177+/-3 to 186+/-4 ms (P<0.01) were observed in 81% and 91% of subjects respectively when comparing PRE and POST. During blood donation, progressive blood loss produced falling trends in LVET(p) (P<0.01) and rising trends in PTT (P<0.01) in FIRST and SECOND, but a falling trend in RRi (P<0.01) was only observed in SECOND. Monitoring trends in timing variables derived from non-invasive ECG and finger PPG signals may facilitate detection of blood loss in the early phase.
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Clin Physiol Funct Imaging · May 2009
Experimental case report: development of a pneumothorax monitored by electrical impedance tomography.
Electrical impedance tomography (EIT) is a non-invasive, radiation-free functional imaging technique, which allows continuous bedside measurement of regional lung ventilation. Pneumothorax is an uncommon but nevertheless potentially dangerous incident that may arise unexpectedly. We report an incident of an accidental tension pneumothorax during an experimental ventilation study in a pig that was continuously monitored by EIT. ⋯ At the same time the ventilation-related impedance changes of the left lung remained almost unchanged. The pneumothorax onset was localized using a newly introduced pneumothorax dynamics map directly derived from dynamic EIT data. We conclude that non-invasive EIT may be helpful as a tool to detect the development of a pneumothorax, which could be of particular interest during invasive procedures such as insertion of a central venous catheter.
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Clin Physiol Funct Imaging · Apr 2009
Quantification of left ventricular volumes and ejection fraction from gated 99mTc-MIBI SPECT: MRI validation of the EXINI heart software package.
The aim of the study was to validate the accuracy of the EXINI heart software (EXINI) package in assessing left ventricular end-diastolic/systolic volumes (EDV, ESV) and ejection fraction (LVEF) from gated (99m)Tc-MIBI single-photon emission tomography (SPECT). Cardiac magnetic resonance imaging (cMRI) was used as reference. Furthermore, effects of perfusion defects and image quality in SPECT on correlation between gated SPECT and magnetic resonance imaging were investigated. ⋯ End-diastolic volume, ESV and LVEF calculated from gated SPECT using EXINI agree with cMRI over a wide range of values. Correlation between both the methods was good for EDV and ESV, and acceptable for LVEF. No relevant influence of image quality or SRS on the accuracy of EXINI results was found.
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Clin Physiol Funct Imaging · Jan 2009
Association of findings in flow-volume spirometry with high-resolution computed tomography signs in asbestos-exposed male workers.
Disorders of pulmonary tissue and pleura are visualized by findings in high-resolution computed tomography (HRCT), and the impairment caused by these findings is assessed by pulmonary function tests. Our aim was to determine how some commonly used spirometric variables are related to certain HRCT signs, in order to find out which HRCT signs are associated with restrictive and which with obstructive ventilatory impairment. ⋯ HRCT signs showed distinctive patterns in restrictive and obstructive ventilatory impairment. These results can be used to help to analyse the lung function of patients simultaneously exposed to asbestos and smoking, when this relationship requires elucidation. In addition, the results may be helpful in explaining some radiological findings.