To the editor,
About 313 million people in the world receive major surgical operations every year,1 and postoperative pulmonary complications (PPCs) are the most common mid-term complications.At present, pulmonary complications are still the main cause of prolonged hospitalization and death in thoracic surgery patients after surgery.2 Therefore, efforts to reduce PPCs are critical to improve the outcome of surgical patients. Lung protective ventilation is defined as the use of low tide and medium to high levels of positive end-expiratory pressure (PEEP) with or without pulmonary retensioning strategy (RM).3 Protective lung ventilation has been shown to reduce morbidity and mortality in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).3 However, the role of protective lung ventilation in the absence of ALI and ARDS remains unclear.The screening progress and detailed methods were presented in Supplementary data. Finally, eight retrospectively studies with 371 patients in lung protection ventilation strategy group and 365 patients in conventional ventilation strategy group were included in this meta-analysis. Details of the basic characteristics of the eight studies are presented in Table 1 .
Table 1.
General information of included literature.
| Study | Type of surgery | Age (yr) | ASA class | Sample size | VT (ml kg−1) | PEEP (cm H2O) | RM | FiO2 |
|---|---|---|---|---|---|---|---|---|
| Ahn | Video-assisted thoracic surgery | NR | 1–2 | 25 | 6 | 5 | N | 0.5 |
| 25 | 10 | 0 | N | 1 | ||||
| Lin | Esophagectomy Oesophagectomy for oesophageal cancer | 41–65 | NR | 20 | 5–6 | 3–5 | N | N |
| 20 | 10 | 0 | N | N | ||||
| Marret | Thoracic surgery | 18–90 | NR | 168 | 5 | 5–8 | N | 0.8 |
| 167 | 10 | 0 | N | 0.8 | ||||
| Maslow | Thoracic surgery | 18–90 | NR | 16 | 5 | 5 | N | 0.6 |
| 16 | 10 | 0 | N | 0.6 | ||||
| Michelet | Oesophagectomy for oesophageal cancer | >18 | NR | 26 | 5 | 5 | N | N |
| 26 | 9 | 0 | N | N | ||||
| Yang | Thoracic surgery | NR | 1–2 | 50 | 6 | 5 | N | 0.5 |
| 50 | 10 | 0 | N | 1 | ||||
| Qutub | video-assisted thoracoscopic surgery | NR | NR | 13 | 6 | 5 | N | 0.5 |
| 13 | 8 | 0 | N | 0.5 | ||||
| Shen | esophagectomy | NR | NR | 53 | 5 | 5 | N | N |
| 48 | 8 | 0 | N | N |
ASA:American Society of Anesthesiologists. VT: Tidal Volume. PEEP: Positive End-expiratory Pressure. FiO2:Fraction of Inspired Oxygen.
The results of our meta-analysis demonstrated that lung protection ventilation strategy group has parallel results with conventional ventilation strategy group regarding postoperative complications confirming the feasibility of lung protection ventilation strategy group, there was no significant difference in terms of perioperative outcomes related to operation, which included postoperative atelectasis(P = 0.48),oxygenation index(P = 0.48) and inflammatory factors IL-8(P = 0.04).The details of results and Forest plots were provided in Supplementary data.In addition, our meta-analysis showed that intraoperative protective ventilation strategies helped reduce lung injury(P = 0.006), pneumonia(P = 0.01), and length of hospital stay(P = 0.002) after thoracic surgery(Fig. 1 ). The details of results and Forest plots were provided in Supplementary data.It can be observed that postoperative pulmonary complications is a serious problem after thoracic surgery.In this meta-analysis, it is suggested that intraoperative lung protective ventilation strategies with PEEP(5-12cmH2O) at medium to high levels (5–8 ml/kg) with or without RM, which is beneficial to reduce the development of postoperative lung injury and pneumoniain in patients undergoing thoracic surgery.
Fig. 1.
Influence of lung protection ventilation strategy on postoperative lung injury in patients undergoing thoracic surgery.
Lung protective ventilation is the use of low tidal volume and limited platform pressure to reduce alveolar hyperdilation, while using PEEP or RM to prevent end-expiratory alveolar collapse.4 As mentioned in this meta-analysis, we believe that moderate to high PEEP has a pulmonary protective effect.In recent years, with the development of perioperative precision medicine, individualized PEEP has gradually attracted the attention of clinical anesthesiologists.Studies have found that, compared with PEEP 5 cmH2O, individualized PEEP can better maintain intraoperative oxygenation and improve respiratory mechanical parameters during single-lung overventilation.5
The common complications in patients with thoracic surgery are pneumonia, atelectasis, lung injury, etc. The main reasons are the deposition of respiratory secretions, adverse sputum discharge, and bacterial infection caused by the decline of body resistance.However, the use of appellate lung protection ventilation strategy can greatly reduce the incidence of postoperative pulmonary complications in patients undergoing thoracic surgery.
Declaration of competing interest
No conflicting financial interests exist between authors.
Acknowledgments
This study was financially supported by Jiangsu province "333 Project" Scientific Research Project (BRA2018020)
Footnotes
Supplementary data to this article can be found online at https://doi.org/10.1016/j.asjsur.2021.02.015.
Appendix A. Supplementary data
The following is the Supplementary data to this article:
References
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