[Atelectasis in general anesthesia and alveolar recruitment strategies]

The effect of inverse ratio ventilation on cardiopulmonary function in obese laparoscopic surgery patients: A systematic review and meta-analysis

This study aimed to evaluate the effect of inverse ratio ventilation (IRV) strategy on cardiopulmonary function in obese patients under general anesthesia. Databases such as China National Knowledge Infrastructure (CNKI), Wangfang, WeiP, Web of Science, the Cochrane Library, and PubMed were systematically searched. All randomized controlled trials' literature on IRV during laparoscopic surgery in obese patients under general anesthesia was collected. After data were extracted and cross-checked, Rev Man 5.3 software was used for meta-analysis. Finally, five randomized controlled clinical trials (RCTs) were included in the meta-analysis, with a total of 312 patients. Compared with the conventional ventilation group, the inspiratory peak pressure was lower at pneumoperitoneum 30 min and pneumoperitoneum 60 min; the PaO2 and oxygenation index were higher at pneumoperitoneum 60 min, and mean airway pressure was higher at pneumoperitoneum 30 min and pneumoperitoneum 60 min; the dynamic lung compliance was superior at pneumoperitoneum 30 min and pneumoperitoneum 60 min. IRV applied to laparoscopic surgery in obese patients under general anesthesia not only reduces peak airway pressure and improves intraoperative oxygenation index and PaO2 but also enhances mean airway pressure and dynamic lung compliance, which has a specific lung protective effect. It can be used as an option for the mechanical ventilation model in obese patients in clinical practice.

ORi™: a new indicator of oxygenation

In the perioperative period, hypoxemia and hyperoxia are crucial factors that require attention, because they greatly affect patient prognoses. The pulse oximeter has been the only noninvasive monitor that can be used as a reference of oxygenation in current anesthetic management; however, in recent years, a new monitoring method that uses the oxygen reserve index (ORi™) has been developed by Masimo Corp. ORi is an index that reflects the state of moderate hyperoxia (partial pressure of arterial oxygen [PaO2] between 100 and 200 mmHg) using a non-unit scale between 0.00 and 1.00. ORi monitoring performed together with percutaneous oxygen saturation (SpO2) measurements may become an important technique in the field of anesthetic management, for measuring oxygenation reserve capacity. By measuring ORi, it is possible to predict hypoxemia and to detect hyperoxia at an early stage. In this review, we summarize the method of ORi, cautions for its use, and suitable cases for its use. In the near future, the monitoring of oxygen concentrations using ORi may become increasingly common for the management of respiratory function before, after, and during surgery.

A new treatment modality for unilateral athelectasis: Recruitment maneuver with endobronchial blocker

Atelectasis is a commonly seen complication during the post-operative period in intensive care units. The treatment of atelectasis depends on the underlying cause. We aimed to share our experience on the treatment of right total atelectasis in our intensive care unit applied with the help of the endobronchial blocker.

The association between nitrous oxide and postoperative mortality and morbidity after noncardiac surgery

BACKGROUND

Nitrous oxide (N2O) has been widely used in clinical anesthesia for >150 years. However, use of N2O has decreased in recent years because of concern about the drug's metabolic side effects. But evidence that routine use of N2O causes clinically important toxicity remains elusive. We therefore evaluated the relationship between intraoperative N2O administration and 30-day mortality as well as a set of major inpatient postoperative complications (including mortality) in adults who had general anesthesia for noncardiac surgery.

METHODS

We evaluated 49,016 patients who had noncardiac surgery at the Cleveland Clinic between 2005 and 2009. Among 37,609 qualifying patients, 16,961 were given N2O ("nitrous," 45%) and 20,648 were not ("nonnitrous," 55%). Ten thousand seven hundred fifty-five nitrous patients (63% of the total) were propensity score-matched with 10,755 nonnitrous patients. Matched nitrous and nonnitrous patients were compared on 30-day mortality and a set of 8 in-hospital morbidity/mortality outcomes.

RESULTS

Inhalation of N2O intraoperatively was associated with decreased odds of 30-day mortality (odds ratio [OR]: 97.5% confidence interval, 0.67, 0.46-0.97; P = 0.02). Furthermore, nitrous patients had an estimated 17% (OR: 0.83, 0.74-0.92) decreased odds of experiencing major in-hospital morbidity/mortality than nonnitrous (P < 0.001). Among the individual morbidities, intraoperative N2O use was only associated with significantly lower odds of having pulmonary/respiratory morbidities (OR, 95% Bonferroni-adjusted CI: 0.59, 0.44-0.78).

CONCLUSIONS

Intraoperative N2O administration was associated with decreased odds of 30-day mortality and decreased odds of in-hospital mortality/morbidity. Aside from its specific and well-known contraindications, the results of this study do not support eliminating N2O from anesthetic practice.