Best practice & research. Clinical anaesthesiology
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Most anesthetics cause a loss of muscle tone that is accompanied by a fall in the resting lung volume. The lowered lung volume promotes cyclic (tidal) or continuous airway closure. ⋯ This chapter deals with these mechanisms in more detail, and it addresses possible measures to keep the lung open with the use of recruitment maneuvers, continuous and/or end-expiratory positive pressure, as well as the interaction with different oxygen concentrations. The effects on ventilation/perfusion matching and pulmonary gas exchange are also discussed.
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Best Pract Res Clin Anaesthesiol · Sep 2015
ReviewIntraoperative mechanical ventilation for the pediatric patient.
Invasive mechanical ventilation is required when children undergo general anesthesia for any procedure. It is remarkable that one of the most practiced interventions such as pediatric mechanical ventilation is hardly supported by any scientific evidence but rather based on personal experience and data from adults, especially as ventilation itself is increasingly recognized as a harmful intervention that causes ventilator-induced lung injury. The use of low tidal volume and higher levels of positive end-expiratory pressure became an integral part of lung-protective ventilation following the outcomes of clinical trials in critically ill adults. ⋯ However, a clear association between tidal volume and mortality has not been ascertained in pediatrics. In fact, experimental studies have suggested that young children might be less susceptible to ventilator-induced lung injury. As such, no recommendations on optimal lung-protective ventilation strategy in children with or without lung injury can be made.
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Best Pract Res Clin Anaesthesiol · Sep 2015
ReviewMechanisms of ventilator-induced lung injury in healthy lungs.
Mechanical ventilation is an essential method of patient support, but it may induce lung damage, leading to ventilator-induced lung injury (VILI). VILI is the result of a complex interplay among various mechanical forces that act on lung structures, such as type I and II epithelial cells, endothelial cells, macrophages, peripheral airways, and the extracellular matrix (ECM), during mechanical ventilation. This article discusses ongoing research focusing on mechanisms of VILI in previously healthy lungs, such as in the perioperative period, and the development of new ventilator strategies for surgical patients. ⋯ Many questions concerning the mechanisms of VILI in surgical patients remain unanswered. The optimal threshold value of each ventilator parameter to reduce VILI is also unclear. Further experimental and clinical studies are necessary to better evaluate ventilator settings during the perioperative period in different types of surgery.
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Best Pract Res Clin Anaesthesiol · Sep 2015
ReviewIntraoperative mechanical ventilation strategies for one-lung ventilation.
One-lung ventilation (OLV) has two major challenges: oxygenation and lung protection. The former is mainly because the ventilation of one lung is stopped while the perfusion continues; the latter is mainly because the whole ventilation is applied to only one lung. ⋯ In light of the (very few) randomized clinical trials, this review focuses on a recent strategy for OLV, which includes a possible decrease in FiO2, lower TVs, positive end-expiratory pressure (PEEP) to the dependent lung, continuous positive airway pressure (CPAP) to the non-dependent lung and recruitment manoeuvres. Other applications such as anaesthetic choice and fluid management can affect the success of ventilatory strategy; new developments have changed the classical approach in this respect.
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Best Pract Res Clin Anaesthesiol · Sep 2015
ReviewIntraoperative mechanical ventilation strategies to prevent postoperative pulmonary complications in patients with pulmonary and extrapulmonary comorbidities.
A variety of patient characteristics and comorbidities have been identified, which increase the risk of postoperative pulmonary complications (PPCs), including smoking, age, chronic obstructive pulmonary disease, pulmonary hypertension, obstructive sleep apnea, cardiac and neurologic diseases as well as critical illness. In contrast to the variety of conditions, evidence for specific intraoperative ventilation strategies to reduce PPC is very limited for most comorbidities. Here, we provide an overview of and discuss possible implications for the intraoperative ventilatory management of patients with comorbidities.