Critical care : the official journal of the Critical Care Forum
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Due to complexities in its measurement, adequacy of ventilation is seldom used to categorize disease severity and guide ventilatory strategies. Ventilatory ratio (VR) is a novel index to monitor ventilatory adequacy at the bedside. VR=(VEmeasured × PaCO₂measured)/(VEpredicted × PaCO₂ideal). VEpredicted is 100 mL.Kg-1.min-1 and PaCO₂ideal is 5 kPa. Physiological analysis shows that VR is influenced by dead space (VD/VT) and CO₂ production (VCO₂). Two studies were conducted to explore the physiological properties of VR and assess its use in clinical practice. ⋯ VR is an easy to calculate bedside index of ventilatory adequacy and appears to yield clinically useful information.
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Marked dysnatremia is associated with increased mortality in patients admitted to intensive care. However, new evidence suggests that even mild deviations from normal and simple variability of sodium values may also be significant. Should these findings prompt clinicians to re-evaluate the approach to fluid management in this setting? Sodium disorders, on one hand, are known to result from overzealous administration or restriction of free water or sodium ions. ⋯ It may be prudent to pay closer attention to these values, especially when abnormal, when fluctuating or when an adverse trend is present. More frequent measurements of sodium in blood, urine and drainage fluids, and appropriate adjustment of the sodium content of prescribed fluids, may be indicated. Until more light can be shed on the pathophysiology of dysnatremia in the critically ill, we should assume that better control of plasma sodium levels may yield better outcomes.
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The lung-protective mechanical ventilation strategy has been standard practice for management of acute respiratory distress syndrome (ARDS) for more than a decade. Observational data, small randomized studies and two recent systematic reviews suggest that lung protective ventilation is both safe and potentially beneficial in patients who do not have ARDS at the onset of mechanical ventilation. ⋯ Patients with a stiff chest wall may tolerate higher plateau pressure targets (approximately 35 cmH2O) while those with severe ARDS and ventilator asynchrony may require a short-term neuromuscular blockade. Given the difficulty in timely identification of patients with or at risk of ARDS and both the safety and potential benefit in patients without ARDS, lung-protective mechanical ventilation is recommended as an initial approach to mechanical ventilation in both perioperative and critical care settings.