Critical care : the official journal of the Critical Care Forum
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Clinical Trial
Heliox reduces respiratory system resistance in respiratory syncytial virus induced respiratory failure.
Respiratory syncytial virus (RSV) lower respiratory tract disease is characterised by narrowing of the airways resulting in increased airway resistance, air-trapping and respiratory acidosis. These problems might be overcome using helium-oxygen gas mixture. However, the effect of mechanical ventilation with heliox in these patients is unclear. The objective of this prospective cross-over study was to determine the effects of mechanical ventilation with heliox 60/40 versus conventional gas on respiratory system resistance, air-trapping and CO2 removal. ⋯ Respiratory system resistance is significantly decreased by mechanical ventilation with heliox (ISCRTN98152468).
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Comparative Study
Expiratory automatic endotracheal tube compensation reduces dynamic hyperinflation in a physical lung model.
The effect of expiratory endotracheal tube (ETT) resistance on dynamic lung inflation is unknown. We hypothesized that ETT resistance causes dynamic lung hyperinflation by impeding lung emptying. We further hypothesized that compensation for expiratory ETT resistance by automatic tube compensation (ATC) attenuates dynamic lung hyperinflation. ⋯ In a lung model of pressure-targeted ventilation, expiratory ETT resistance caused dynamic lung hyperinflation during increases in respiratory rates, thereby reducing inspiratory tidal volume. Expiratory ATC attenuated these adverse effects.
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Septic patients may require anaesthesia for surgery or to facilitate endotracheal intubation for respiratory failure. These patients frequently start with a deranged haemodynamic state, including vasodilation with hypotension, and cardiomyopathy, making induction of anaesthesia a potentially hazardous task. ⋯ Before induction, the physician should understand the haemodynamic state (especially using echocardiography), should restore cardiovascular reserve with inotropes and vasopressors, and should induce anaesthesia with the smallest dose of the safest drug. In the previous issue of Critical Care, Zausig and colleagues show that propofol may not be the safest choice of induction agent in septic patients.
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Comparative Study
Differential influence of arterial blood glucose on cerebral metabolism following severe traumatic brain injury.
Maintaining arterial blood glucose within tight limits is beneficial in critically ill patients. Upper and lower limits of detrimental blood glucose levels must be determined. ⋯ Maintaining arterial blood glucose levels between 6 and 8 mmol/l appears superior compared with lower and higher blood glucose concentrations in terms of stabilised cerebral metabolism. It appears that arterial blood glucose values below 6 and above 8 mmol/l should be avoided. Prospective analysis is required to determine the optimal arterial blood glucose target in patients suffering from severe TBI.
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Comparative Study
Changes in skeletal muscle oxygenation during exercise measured by near-infrared spectroscopy on ascent to altitude.
We sought to quantify changes in skeletal muscle oxygenation during exercise using near-infrared spectroscopy (NIRS) in healthy volunteers ascending to high altitude. ⋯ In most individuals, NIRS can be used to measure exercising skeletal muscle oxygenation in the field. During exercise the patterns of absolute oxygenation are broadly similar at altitude and SL. Following prolonged adaptation to altitude, the rate of muscle desaturation is more rapid than observed at SL but less so in those exposed to extreme hypoxia above 5,300 m.