45 research outputs found
Therapeutic benefits of proning to improve pulmonary gas exchange in severe respiratory failure: Focus on fundamentals of physiology
NEW FINDINGS: What is the topic of this review? The use of proning for improving pulmonary gas exchange in critically ill patients. What advances does it highlight? Proning places the lung in its ânaturalâ posture, and thus optimises the ventilationâperfusion distribution, which enables lung protective ventilation and the alleviation of potentially lifeâthreatening hypoxaemia in COVIDâ19 and other types of critical illness with respiratory failure. ABSTRACT: The survival benefit of proning patients with acute respiratory distress syndrome (ARDS) is well established and has recently been found to improve pulmonary gas exchange in patients with COVIDâ19âassociated ARDS (CARDS). This review outlines the physiological implications of transitioning from supine to prone on alveolar ventilationâperfusion ([Formula: see text]) relationships during spontaneous breathing and during general anaesthesia in the healthy state, as well as during invasive mechanical ventilation in patients with ARDS and CARDS. Spontaneously breathing, awake healthy individuals maintain a small vertical (ventralâtoâdorsal) [Formula: see text] ratio gradient in the supine position, which is largely neutralised in the prone position, mainly through redistribution of perfusion. In anaesthetised and mechanically ventilated healthy individuals, a vertical [Formula: see text] ratio gradient is present in both postures, but with better [Formula: see text] matching in the prone position. In ARDS and CARDS, the vertical [Formula: see text] ratio gradient in the supine position becomes larger, with intrapulmonary shunting in gravitationally dependent lung regions due to compression atelectasis of the dorsal lung. This is counteracted by proning, mainly through a more homogeneous distribution of ventilation combined with a largely unaffected high perfusion dorsally, and a consequent substantial improvement in arterial oxygenation. The data regarding proning as a therapy in patients with CARDS is still limited and whether the associated improvement in arterial oxygenation translates to a survival benefit remains unknown. Proning is nonetheless an attractive and lung protective manoeuvre with the potential benefit of improving lifeâthreatening hypoxaemia in patients with ARDS and CARDS
Progressive intracranial hypertension and cerebral hypoperfusion in a fatal case of cerebral aspergilloma
We report a case of cerebral aspergilloma in a 25-year-old immunoincompetent man admitted to a general intensive care unit. Monitoring of intracranial pressure was instigated and revealed hour-long epochs of severe intracranial hypertension, despite a normal opening pressure, with decreases in cerebral perfusion pressure. We documented that this was associated with cerebral hypoperfusion by transcranial Doppler ultrasound. The present case illustrates that severe intracranial hypertension may evolve despite a normal opening pressure; it furthermore shows that continuous monitoring of intracranial pressure may be used to predict changes in cerebral haemodynamics in critically ill patients with neuroinfection