Abstract
The pulse oximeter waveform (POW) is derived from variation in intensity of transmitted light through tissues. It may be used to provide a non-invasive surrogate for the intra-arterial waveform, and represents an accessible measure of cardiovascular status. We examined the effects of age, blood pressure and smoking on the waveform patterns. These factors are known to decrease arterial compliance, increase peripheral wave reflection and alter the contour of the pulse pressure waveform. Supine and standing POW recordings were taken from 200 healthy volunteers. The resting waveform patterns were categorised into four distinct classes as described by Murgo and Nichols for intra-arterial pressure waveforms, and compared to age and systolic blood pressure. Post hoc ANOVA revealed a significant relationship between waveform class and age (P < 0.001), blood pressure (P < 0.001), and smoking status (P = 0.021. These effects appear to represent changes in the peripheral arterial system resulting from altered wave reflection. We also analysed the POW in both time and frequency domains. On standing, time domain analysis showed a decrease in total variability, as measured by standard deviation and variance. Frequency domain analysis demonstrated an increase in power at a frequency (0.1 Hz) associated with sympathetic nervous system output. These results are consistent with changes in the microcirculation related to autonomic control mechanisms. These patterns of change, however, were only apparent in a proportion of the subjects. We believe that the responses elicited are dependent on factors affecting the long-term compliance of the arterial tree, and are thus related to the pulse oximeter waveform classification described. We have shown that POW analysis yields consistent and reproducible patterns. Further research may lead to the use of these techniques as a measure of peripheral vascular responsiveness, with potential utility in the evaluation of cardiovascular disease.
Highlights
In our experience, very often, even with a nonrebreathing mask (NRM), high oxygen delivery to patient with the existent materials is insufficient
TMSORG for R, C, N and Re were significantly associated with HM
P109 How we reduce allogenic blood transfusions in the patients undergoing surgery of ascending aorta D Radojevic, Z Jankovic, B Calija, M Jovic, B Djukanovic
Summary
Very often, even with a nonrebreathing mask (NRM), high oxygen delivery to patient with the existent materials is insufficient. There is evidence that increasing the dose of continuous renal replacement therapy (CRRT) is associated with improved survival in critically ill patients with acute renal failure (ARF) [1]. The aim of this study is to investigate if there is any difference in patients’ characteristics in ICU between COPD and nonCOPD diseases caused chronic respiratory failure and require mechanical ventilation during acute exacerbations. Noninvasive positive pressure ventilation (NPPV) has been reported to be beneficial in the treatment of acute exacerbation of chronic obstructive pulmonary disease (COPD), and to facilitate weaning In this trial we assessed the possible benefit of early NPPV in patients with blunt chest trauma and acute respiratory failure. The aim of this study was to compare the pharmacokinetic and pharmacodynamic parameters and the clinical efficacy of a continuous infusion of cefepime versus an intermittent regimen in critically ill adults patients with gram negative bacilli infection. The purpose of the study is to identify the factors associated with DNR status in our institution
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