Do we need randomized clinical trials in extracorporeal respiratory support? Yes

Feasibility and safety of low-flow extracorporeal CO2 removal managed with a renal replacement platform to enhance lung-protective ventilation of patients with mild-to-moderate ARDS

BACKGROUND

Extracorporeal carbon-dioxide removal (ECCO₂R) might allow ultraprotective mechanical ventilation with lower tidal volume (VT) (< 6 ml/kg predicted body weight), plateau pressure (P_plat) (< 30 cmH₂O), and driving pressure to limit ventilator-induced lung injury. This study was undertaken to assess the feasibility and safety of ECCO₂R managed with a renal replacement therapy (RRT) platform to enable very low tidal volume ventilation of patients with mild-to-moderate acute respiratory distress syndrome (ARDS).

METHODS

Twenty patients with mild (n = 8) or moderate (n = 12) ARDS were included. VT was gradually lowered from 6 to 5, 4.5, and 4 ml/kg, and PEEP adjusted to reach 23 ≤ P_plat ≤ 25 cmH₂O. Standalone ECCO₂R (no hemofilter associated with the RRT platform) was initiated when arterial PaCO₂ increased by > 20% from its initial value. Ventilation parameters (VT, respiratory rate, PEEP), respiratory system compliance, P_plat and driving pressure, arterial blood gases, and ECCO₂R-system operational characteristics were collected during at least 24 h of very low tidal volume ventilation. Complications, day-28 mortality, need for adjuvant therapies, and data on weaning off ECCO₂R and mechanical ventilation were also recorded.

RESULTS

While VT was reduced from 6 to 4 ml/kg and P_plat kept < 25 cmH₂O, PEEP was significantly increased from 13.4 ± 3.6 cmH₂O at baseline to 15.0 ± 3.4 cmH₂O, and the driving pressure was significantly reduced from 13.0 ± 4.8 to 7.9 ± 3.2 cmH₂O (both p < 0.05). The PaO₂/FiO₂ ratio and respiratory-system compliance were not modified after VT reduction. Mild respiratory acidosis occurred, with mean PaCO₂ increasing from 43 ± 8 to 53 ± 9 mmHg and mean pH decreasing from 7.39 ± 0.1 to 7.32 ± 0.10 from baseline to 4 ml/kg VT, while the respiratory rate was not altered. Mean extracorporeal blood flow, sweep-gas flow, and CO₂ removal were 421 ± 40 ml/min, 10 ± 0.3 L/min, and 51 ± 26 ml/min, respectively. Mean treatment duration was 31 ± 22 h. Day-28 mortality was 15%.

CONCLUSIONS

A low-flow ECCO₂R device managed with an RRT platform easily and safely enabled very low tidal volume ventilation with moderate increase in PaCO₂ in patients with mild-to-moderate ARDS.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02606240. Registered on 17 November 2015.

[Organ assist devices in the future : Limits and perspectives]

In the last decade, extracorporeal organ assist devices (extracorporeal membrane oxygenation [ECMO]) have been increasingly applied to treat the most severe forms of respiratory failure and cardiogenic shock, although the underlying scientific evidence is still limited and the methods carry a high risk of complications despite all technical improvements. The selection of those patients who most benefit from these devices is still a great challenge for intensivists and all other involved disciplines. Besides the severity of the acute organ failure, it is important to thoroughly evaluate etiology and treatment options of the underlying disease, comorbidities, and the functional status of the patients in an interdisciplinary team. This also includes ethical challenges. Because of the complexity of the treatment and the high organizational demands it is reasonable to concentrate ECMO treatments in specifically qualified centers and to promote a comprehensive scientific analysis of the treatment data.