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In patients with uninjured lungs, increasing evidence indicates that tidal volume (VT) reduction improves outcomes in the intensive care unit (ICU) and in the operating room (OR). However, the degree to which this evidence has translated to clinical changes in ventilator settings for patients with uninjured lungs is unknown. To clarify whether ventilator settings have changed, we searched MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science for publications on invasive ventilation in ICUs or ORs, excluding those on patients <18 years of age or those with >25% of patients with acute respiratory distress syndrome (ARDS). Our primary end point was temporal change in VTover time. Secondary end points were changes in maximum airway pressure, mean airway pressure, positive end-expiratory pressure, inspiratory oxygen fraction, development of ARDS (ICU studies only), and postoperative pulmonary complications (OR studies only) determined using correlation analysis and linear regression. We identified 96 ICU and 96 OR studies comprising 130,316 patients from 1975 to 2014 and observed that in the ICU, VTsize decreased annually by 0.16 mL/kg (−0.19 to −0.12 mL/kg) (P< .001), while positive end-expiratory pressure increased by an average of 0.1 mbar/y (0.02–0.17 mbar/y) (P= .017). In the OR, VTsize decreased by 0.09 mL/kg per year (−0.14 to −0.04 mL/kg per year) (P< .001). The change in VTs leveled off in 1995. Other intraoperative ventilator settings did not change in the study period. Incidences of ARDS (ICU studies) and postoperative pulmonary complications (OR studies) also did not change over time. We found that, during a 39-year period, from 1975 to 2014, VTs in clinical studies on mechanical ventilation have decreased significantly in the ICU and in the OR.

Published ahead of print June 19, 2017.

Supplemental Digital Content is available in the text.Published ahead of print February 1, 2016

For many years, mechanical ventilation with high tidal volumes (VT) was common practice in operating theaters because this strategy recruits collapsed lung tissue, improves ventilation–perfusion mismatch, and thus decreases the need for high oxygen fractions. Positive end-expiratory pressure (PEEP) was seldom used because it could cause cardiac compromise. Increasing advances in the understanding of the mechanisms of ventilator-induced lung injury from animal studies and randomized controlled trials in patients with uninjured lungs in intensive care unit and operation room have pushed anesthesiologists to consider lung-protective strategies during intraoperative ventilation. These strategies at least include the use of low VT, and perhaps also the use of PEEP, which when compared to high VTwith low PEEP may prevent the occurrence of postoperative pulmonary complications (PPCs). Such protective effects, however, are likely ascribed to low VTrather than to PEEP. In fact, at least in nonobese patients undergoing open abdominal surgery, high PEEP does not protect against PPCs, and it can impair the hemodynamics. Further studies shall determine whether a strategy consisting of low VTcombined with PEEP and recruitment maneuvers reduces PPCs in obese patients and other types of surgery (e.g., laparoscopic and thoracic), compared to low VTwith low PEEP. Furthermore, the role of driving pressure for titrating ventilation settings in patients with uninjured lungs shall be investigated.

This educational narrative review provides a summary of non-ventilatory strategies to prevent postoperative pulmonary complications (PPCs). It highlights patient- and procedure-related risk factors for PPCs that are non-modifiable, potentially modifiable, or well modifiable. Non-ventilatory strategies, mainly based on the modification of risk factors, play a key role in reducing PPCs. Non-modifiable risk factors, most importantly age, American Society of Anesthesiologists (ASA) class, and risk of the procedure, should be recognized and patients intensively screened for the potential to optimize other, potentially or well-modifiable, risk factors. Potentially modifiable risk factors, mainly comorbidities and the surgical approach, increase the risk of PPCs. Patient-related factors can be improved while procedure-related factors may be adapted in high-risk patients. Well-modifiable risk factors, mainly certain anesthesia techniques, for example, general anesthesia, intravenous opioids or liberal fluid management, and smoking or alcohol abuse, should be avoided as far as possible in order to prevent PPCs.

This review summarizes the most recent clinical and experimental data on the impact of spontaneous breathing in acute respiratory distress syndrome (ARDS).

Intravenous fluid administration is often required to counteract haemodynamic instability during emergency and elective surgeries, as well as in the intensive care unit. However, the best type and the amount of fluid required are controversial. A recent meta-analysis suggested that there is no difference among different types of colloids on outcome. Furthermore, colloids and crystalloids seem to be comparable in terms of efficiency in reverting haemodynamic instability, as well as morbidity and mortality. The interpretation of the results of different randomised controlled trials is somewhat difficult – the context must be always kept in mind. For example, results may differ in septic as compared to non-septic patient populations. Another important aspect concerns the effects on the macro- versus microcirculation. More recent studies emphasise that the microcirculation has to be taken into account when studying and interpreting the interaction between fluid therapy and the underlying disease. Nevertheless, the macrocirculation and clinical parameters have to be considered as well. Given that red blood cells remain the most important oxygen carriers, recent evidence regarding blood age may stimulate new studies according to the actual range for blood storage. Artificial oxygen carriers may play a role in specific situations, where the transfusion is indicated but the access to blood is problematic, but there is doubt that they may replace blood transfusion.

We aimed at providing the most recent and relevant evidence regarding spontaneous breathing activity during mechanical ventilation in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Both clinical and experimental data are depicted.

Recruitment maneuvers (RMs) seem to be more effective in extrapulmonary acute lung injury (ALI), caused mainly by sepsis, than in pulmonary ALI. Nevertheless, the maintenance of adequate volemic status is particularly challenging in sepsis. Since the interaction between volemic status and RMs is not well established, we investigated the effects of RMs on lung and distal organs in the presence of hypovolemia, normovolemia, and hypervolemia in a model of extrapulmonary lung injury induced by sepsis.

There is an increasing interest in biphasic positive airway pressure with spontaneous breathing (BIPAP+SBmean), which is a combination of time-cycled controlled breaths at two levels of continuous positive airway pressure (BIPAP+SBcontrolled) and non-assisted spontaneous breathing (BIPAP+SBspont), in the early phase of acute lung injury (ALI). However, pressure support ventilation (PSV) remains the most commonly used mode of assisted ventilation. To date, the effects of BIPAP+SBmean and PSV on regional lung aeration and ventilation during ALI are only poorly defined.