Management of Intraoperative Mechanical Ventilation to Prevent Postoperative Complications after General Anesthesia: A Narrative Review

Mechanical ventilation (MV) is still necessary in many surgical procedures; nonetheless, intraoperative MV is not free from harmful effects. Protective ventilation strategies, which include the combination of low tidal volume and adequate positive end expiratory pressure (PEEP) levels, are usually adopted to minimize the ventilation-induced lung injury and to avoid post-operative pulmonary complications (PPCs). Even so, volutrauma and atelectrauma may co-exist at different levels of tidal volume and PEEP, and therefore, the physiological response to the MV settings should be monitored in each patient. A personalized perioperative approach is gaining relevance in the field of intraoperative MV; in particular, many efforts have been made to individualize PEEP, giving more emphasis on physiological and functional status to the whole body. In this review, we summarized the latest findings about the optimization of PEEP and intraoperative MV in different surgical settings. Starting from a physiological point of view, we described how to approach the individualized MV and monitor the effects of MV on lung function.

Pulmonary Complications After Open Abdominal Aortic Surgery: A Systematic Review and Meta-Analysis

OBJECTIVES

Postoperative pulmonary complications (PPC) are among the most common complications after noncardiac surgery. Men, smokers, and elderly patients with chronic obstructive pulmonary disease or heart failure are more likely to experience PPC. The majority of patients undergoing vascular surgery belong in these categories and are at higher risk of developing PPC. Moreover, the surgical site is one of the most important risk factors associated with PPC, and aortic surgery carries the highest risk. The aim of this systematic review was to obtain an additional understanding of the real incidence of PPC after open abdominal aortic surgery and the impact of PPC on survival.

DESIGN

Systematic review and meta-analysis.

SETTING

Hospitals PARTICIPANTS: Patients who underwent open abdominal aortic surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A literature search was performed on BioMedCentral, PubMed, Embase, and the Cochrane Register of clinical trials. All prospective or retrospective studies reporting data on PPC after open abdominal aortic surgery were included. Co-primary endpoints were the PPC rate and the correlation between PPC and perioperative mortality. The secondary endpoint was the difference in the PPC rate and mortality between elective and urgent surgery. Data on 269,637 patients from 213 studies were analyzed. The overall median incidence of PPC was 10.3% (interquartile range 5.55%-19.1%). Pneumonia, respiratory insufficiency, prolonged mechanical ventilation, need for unplanned mechanical ventilation, atelectasis, acute respiratory distress syndrome, pulmonary edema, and pleural effusions were the most common PPC reported in the literature. Occurrence of PPC was associated with postoperative mortality (r = 0.65, p<0.01) and was significantly higher in urgent procedures (p<0.001).

CONCLUSIONS

Incidence of PPC after open abdominal aortic surgery is high and is associated with increased postoperative morbidity and mortality.

Right upper lobe atelectasis after tracheal extubation in a morbidly obese patient

Background:

Acute lobar collapse caused by a reflex bronchoconstriction was previously reported to occur during the induction of anesthesia, however there are no reports on its occurrence during the emergence period.

Case Report:

A 56-year-old morbidly obese woman was scheduled for surgery due to a gastric ulcer perforation. Anesthesia was induced with thiopental 500 mg, fentanyl and rocuronium, and maintained with sevoflurane in a N₂O/O₂ mixture. The operative procedure and anesthesia were uneventful; however, the patient developed a sudden decrease in SaO₂ and blurring of consciousness after extubation. She was re-intubated and ventilated with 100% O₂. Arterial blood gas analysis at that time showed respiratory acidosis and hypoxemia. Further work-up revealed a bronchospasm-induced right upper lobe atelectasis, which occurred immediately after tracheal extubation. The patient was successfully treated using mechanical ventilation and bronchodilators.

Conclusions:

Bronchospasm may cause acute lobar atelectasis immediately after tracheal extubation. Morbid obesity and the use of 100% oxygen may facilitate atelectasis formation during emergence from anesthesia.