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Table 1 Summary of key studies on prone positioning in patients with acute respiratory distress syndrome (ARDS) treated with extracorporeal membrane oxygenation (ECMO)

From: To prone or not to prone ARDS patients on ECMO

Reference

Type of study

Patients included

Prone position characteristics

Main results

Adverse events

Kipping et al. [19]

Retrospective cohort

12

Duration of prone sessions: 8 h Number of prone sessions: median of 6 (IQR 4–8)

Total number of prone sessions: 74

58% reported an improvement in the PaO2/FiO2 ratio > 20%

No change in MAP, HR, but mPAP significantly increased during proning and decreased after proning

Dose of norepinephrine could also be decreased

One lost NGT

Bleeding from ECMO cannulation sites (11/74) or tracheal tube (10/74) or central venous lines (8/74) or chest tubes (10/74) One endotracheal tube obstruction One pulmonary embolism Drop in SpO2 > 2% (10/74) One temporary reduced blood flow of ECMO

Hemodynamic instability (7/74) Temporary bradycardia (3/74)

Masuda et al. [20]

Cohort

5

Duration of prone sessions: mean 15.3 ± 0.5 h Number of prone sessions: mean 1.8 ± 0.8

Oxygenation improvement: PaO2/FiO2 ratio in supine 143 ± 38 mmHg vs. prone 263 ± 99 mmHg

None

Guervilly et al. [21]

Prospective cohort

15

Initiation after a median of 9 (IQR 5–10) days on ECMO

Duration of prone sessions: 12 h Number of prone sessions: 1.4 per patient

Total number of prone sessions: 21

Oxygenation improvement: PaO2/FiO2 ratio increased from 103 (78–135) vs. 160 (96–215); P = 0.007

The oxygenation improvement persisted after returning the patients to the supine position

No changes in PaCO2 and Crs were observed

No major adverse events Variations in ECMO flow were small (1.6 ± 4% compared to baseline)

Two patients required crystalloid infusions of 500 ml for MAP < 65 mmHg during proning One pneumothorax occurring during proning was diagnosed and drained only after returning to supine position

Kimmoun et al. [18]

Retrospective cohort

17

Initiation after a median of 6 (4–12) days on ECMO Duration of prone sessions: 24 h Total number of prone sessions: 27

Oxygenation improvement: PaO2/FiO2 ratio in supine 111 (IQR 84–128) mmHg vs. at the end of prone session 173 (120–203) mmHg

Oxygenation improvement occurred more frequently in patients who were proned after 7 days of ECMO therapy Improvement in Crs: From 18 (12–36) to 32 (15–36) ml/ cmH2O 24 h after the return to supine position, tidal volume was increased from 3.0 (2.2–4.0) to 3.7(2.8–5.0) ml/kg No correlation was observed between the oxygenation improvement and the amount of non-aerated lung tissue in the CT scan

One membrane thrombosis, one drop in ECMO blood flow

Lucchini et al. [22]

Retrospective cohort

14

Duration of prone sessions: median 8 h (IQR 6–10)

Number of prone sessions: (median 1—IQR 1–1.5) Total number of prone sessions: 45

Oxygenation improvement: PaO2/FiO2 ratio in supine 123 (IQR 82–135) mmHg and at the end of prone session 149 (90–186) mmHg

This improvement was not maintained when the patient was turned to supine 113 (74–182)

No significant hemodynamic variations (HR, SAP, PAPm, CO, PWP, SvO2)

None

Rilinger et al. [26]

Retrospective cohort propensity score matched

38

Initiation after a median of 1.7 (0.5–5.0) days on ECMO

Duration of prone sessions: median 19.5 (IQR 16.8–20.8) hours Number of prone sessions: 2 (1–3)

No difference in hospital survival (36.8% vs. 36.8%, P = 1.0) No difference in ECMO weaning rate (47.4% vs. 44.7%, P = 0.82)

Hospital survival was superior in the subgroup of patients treated with early proning (< 17 h) as compared to late or no proning (81.8% vs. 33.3%, P = 0.02) 60-day mortality was 18% for the early proning and 65% for the late and no proning group, respectively (P = 0.027) Survival rate of early proning was higher compared to late proning or no prone (81.8% vs. 18.5% and 36.7%, P < 0.001 and P = 0.003, respectively)

No relevant complications

Franchineau et al. [25]

Prospective cohort

21

Duration of prone sessions: 16 h

Static Crs during proning increased from 23 (17–29) to 27 (20–37) ml/cmH2O (P < 0.01) 13 (62%) patients increased their static Crs by 3 ml/cmH2O after proning on ECMO (mechanical responders) EELI was redistributed from ventral to dorsal regions during proning

Optimal PEEP determined by EIT was lower in prone position (14 (12–16) vs. 10 (8–14) cmH2O

None

Garcia et al. [23]

Retrospective cohort

14 (SARS- CoV-2)

Duration of prone sessions: median 16 h (IQR 15–17) Total number of prone sessions: 24

Oxygenation improvement: PaO2/FiO2 ratio in supine 84 (IQR 73–108) vs 112 (83–157) after proning

The median PaO2/FiO2 ratio improvement after proning was 28% [2–36]. 62.5% high responders (increase PaO2/ FiO2 ratio > 20%), 16.7% moderate- responders (increase PaO2/FiO2 < 20%), and 20.8% non- responders (decrease PaO2/FiO2)

Patients in the prone ECMO group were less likely to be weaned from ECMO, and 28-day mortality rate was significantly higher

Three minor hemorrhages at site of cannula insertion

Three moderate flow drops of VV-ECMO that required fluid resuscitation

Giani et al. [24]

Multicenter retrospective cohort propensity score matched

240 patients (66 matched pairs)

Initiation after a median of 4 (IQR 2–7) days on ECMO Duration of proning: mean 15 (12–18) h Total number of prone sessions: 326

Improvement in oxygenation, intrapulmonary shunt fraction and static Crs that persisted after supination Minor differences in hemodynamics (mPAPm and PWP were slightly higher during proning and HR was lower) Lower hospital mortality in proned patients (OR = 0.50, 95%CI: 0.29–0.87)

PS matched cohort: proned patients had a lower mortality (30% vs. 53%, P = 0.0241) proned patients had a longer duration of ECMO (16 vs10 days, P = 0.0344)

No major complication 6% minor complications Six procedures aborted due to respiratory or hemodynamic instability during prone positioning

  1. IQR interquartile range, PaO2/FiO2 ratio of arterial oxygenation to fraction of inspired oxygen, MAP mean arterial pressure, HR heart rate, mPAP mean pulmonary arterial pressure, NGT nasogastric tube, PaCO2 partial pressure of carbon dioxide in the arterial blood, Crs respiratory system compliance, SAP systolic arterial pressure, CO cardiac output, EELI end-expiratory lung impedance, PEEP positive end-expiratory pressure, EIT electrical impedance tomography