Table 2.
Study characteristics
| Study | Surgery | Age (years) |
No.of patients (male/female) |
ASA | FiO2(%) | TV (ml/kg) |
PEEP (cmH2O) |
LRM (Ultrasound-guided) | LRM (Control) |
|---|---|---|---|---|---|---|---|---|---|
| Lee 2020 | Simple, superficial surgeries | ≤ 6 years |
86 (34/52) |
N | 0.4 | 8 | 5 | The recruitment maneuver was performed under ultrasound guidance,a steady airway pressure of 15 cmH2O, with 5 cmH2O increments in PEEP until a peak pressure of 30 cmH2O was achieved | The recruitment maneuver was performed by maintaining a steady airway pressure of 15 cmH2O, with 5 cmH2O increments in PEEP until a peak pressure of 30 cmH2O was achieved |
| Song 2017 | Elective minor surgery | ≤ 1 years |
40 (25/15) |
I–II | 0.4 | 8 | 5 | The recruitment maneuver was performed after each lung ultrasound examination; a stepwise increase in airway pressure from 10 cmH2O by 5 cmH2O increments was applied manually | None |
| Park 2021 | Laparoscopic gynaecological surgery | N |
40 (0/40) |
I–II | 0.4 | 8 | 5 | Manual inflation was applied until no collapsed areas were visible on the ultrasound | The recruitment maneuver was performed by manual inflation with a pressure of 30 cmH2O for 10 s |
| Liu 2022 | Laparoscopic gynecologic surgery | 18–65 years |
41 (0/41) |
I–II | 0.4 | 6–8 | 6 | The maximum airway pressure was set to start at 10 cmH2O and gradually increased by 5 cmH2O until the collapsed lung area was not visible on ultrasound | None |
| Jang 2020 | Elective non-cardiac surgery in the prone position | < 3 years |
40 (20/20) |
N | 0.4 | 6 | 7 | Alveolar recruitment to restore FRC with 30–40 cmH2O of continuous positive airway pressure via a closed system for approximately 5–10 s | None |
| Yang 2021 | Laparoscopic surgery for colorectal carcinoma | ≥ 60 years |
40 (30/10) |
I–III | 0.4 | 6–8 | 4 | The recruitment maneuver was performed with a gradual rise in airway pressure from 10 cmH2O to 5 cmH2O increments and it was applied manually until no collapsed lung areas were visible on the sonogram | None |
| Acosta 2018 | Non-emergency and non-thoracic surgery | 6 months–7 years |
42 (36/6) |
I–II | 0.5 | 6 | 5 | The recruitment maneuver was performed after a lung ultrasound examination.PEEP was increased in steps of 5 cmH2O, from 5 to 15 cmH2O, every three breaths. The target recruitment pressure of 30 cmH2O was maintained for 10 breaths | None |
| Acosta 2021 | Non-emergency and non-thoracic surgery | 6 months–7 years |
41 (26/15) |
I | 0.4 | 7 | 5 | The recruitment maneuver was performed after a lung ultrasound examination.PEEP was increased in steps of 5 cmH2O, from 5 to 15 cmH2O, every three breaths. The target recruitment pressure of 30 cmH2O was maintained for 10 breaths | None |
| Acosta 2020 | Non-emergency and non-thoracic surgery | 6 months–5 years |
40 (27/13) |
I–II | 0.5 | 6 | 5 | Ventilation was turned to pressure control ventilation using a driving pressure of 12 cmH2O and PEEP of 10 cmH2O, but they were immediately and sequentially placed: (1) in the left lateral position (90 s), (2) in the right lateral position (other 90 s), (3) back to the supine position | None |
SD standard deviation, ASA American Society of Anesthesiologists, BMI body mass index, PEEP positive end-expiratory pressure, C control, LRM lung recruitment maneuver, TV tidal volume, FiO2 fraction of inspired oxygen, FRC functional residual capacity, CPAP continuous positive airway pressure, N not reported