BMC anesthesiology
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In the assessment of hypovolemia the value of functional hemodynamic monitoring during spontaneous breathing is debated. The aim of our study was to investigate in spontaneously breathing subjects the changes in hemodynamic parameters during graded central hypovolemia and to test whether slow patterned breathing improved the discriminative value of stroke volume (SV), pulse pressure (PP), and their variations (SVV, PPV). In addition, we tested the alterations in labial microcirculation. ⋯ Functional hemodynamic monitoring with slow patterned breathing to control spontaneous respiration may be worthy for further study in different populations for the assessment of hypovolemia and the prediction of volume responsiveness.
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Microcirculatory driving pressure is defined as the difference between post-arteriolar and venular pressure. In previous research, an absence of correlation between mean arterial blood pressure (MAP) and microcirculatory perfusion has been observed. However, the microcirculation may be considered as a low pressure compartment with capillary pressure closer to venous than to arterial pressure. From this perspective, it is conceivable that central venous pressure (CVP) plays a more important role in determination of capillary perfusion. We aimed to explore associations between CVP and microcirculatory perfusion. ⋯ We observed a significant association between a higher CVP and impairment of microcirculatory blood flow. Further research is needed to elaborate on our hypothesis generating findings that an elevated CVP may act as an outflow obstruction of organ perfusion.
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Ultrasound gels may contain propylene glycol and glycerol, which are neurotoxic in high concentrations. If the needle passes through gel during regional anesthesia, gel may be injected near the nerve. It is unknown if this practice poses a risk for neurotoxicity. Using an animal model, we assessed the histological changes of perineural propylene glycol on nerves. We then assessed three commonly used sterile gels for evidence of neurotoxicity. ⋯ Similar to glycerol, 70% PG may cause confluent areas of axon and myelin degeneration with associated intraneural inflammation. The concentration of PG present in ultrasound gels is unlikely to cause neurotoxicity. Aquasonic® 100 and PDI® Lubricating Jelly did not cause neurotoxicity. The results for K-Y® Lubricating Jelly are inconclusive. There is no evidence that passing the needle through the studied gels during regional anesthesia procedures is harmful.
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The primary objective of this study was to determine the efficiency of a pneumatic device in controlling cuff pressure (Pcuff) in patients intubated with polyurethane-cuffed tracheal tubes. Secondary objectives were to determine the impact of continuous control of Pcuff, and cuff shape on microaspiration of gastric contents. ⋯ The pneumatic device was efficient in controlling Pcuff in critically ill patients intubated with polyurethane-cuffed tracheal tubes.
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Poor characterization of propofol pharmacokinetics and pharmacodynamics in the morbidly obese (MO) pediatric population poses dosing challenges. This study was conducted to evaluate propofol total intravenous anesthesia (TIVA) in this population. ⋯ Our findings indicate clinical overestimation of propofol requirements and highlight the challenges of clinically titrated propofol TIVA in MO adolescents. In this setting, it may be advantageous to titrate propofol to targeted BIS levels until more accurate weight-appropriate dosing regimens are developed, to minimize relative overdosing and its consequences.