British journal of anaesthesia
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The i.v. anaesthetic propofol produces bronchodilatation. Airway relaxation involves reduced intracellular Ca(2+) ([Ca(2+)](i)) in airway smooth muscle (ASM) and lipid rafts (caveolae), and constitutional caveolin proteins regulate [Ca(2+)](i). We postulated that propofol-induced bronchodilatation involves caveolar disruption. ⋯ These novel data suggest a role for caveolae (specifically caveolin-1) in propofol-induced bronchodilatation. Due to its lipid nature, propofol may transiently disrupt caveolar regulation, thus altering ASM [Ca(2+)](i).
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A potential practical approach for continuous and minimally invasive cardiac output (CO) monitoring in intensive care unit (ICU) patients is to mathematically analyse an arterial pressure (AP) waveform using an existing radial artery line ('pulse contour analysis'). We recently proposed a technique to estimate the relative CO change by unique long time interval analysis (LTIA) of an AP waveform. We aimed to test this technique in an ICU patient population and compare its accuracy relative to other techniques. ⋯ The LTIA technique attained an overall accuracy that may be considered clinically acceptable after taking into account the known thermodilution error and became progressively more accurate than previous techniques with increasing CO changes.
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We evaluated the ability of an infrared photoplethysmography arterial waveform (continuous non-invasive arterial pressure, CNAP) to estimate arterial pulse pressure variation (PPV). We compared the ability of non-invasive PPV to predict fluid responsiveness with invasive PPV, respiratory variation of pulse contour-derived stroke volume, and changes in cardiac index induced by passive leg raising (PLR) and end-expiratory occlusion (EEO) tests. ⋯ Non-invasive assessment of PPV seems valuable in predicting fluid responsiveness.