Although the differential for drainage insufficiency is broad, most references recommend fluid loading as first-line management [11, 12]. With recent data suggesting positive fluid balance is associated with prolonged ECMO duration and reduced survival [13,14,15], a more targeted approach may be prudent (Fig. 1).
Management of drainage insufficiency should be aimed at restoring the mismatch between venous return and pressure at the drainage port. As a first step, the pump speed should be reduced until blood flow is stable. If the patient remains adequately supported, the lower pump speed should be maintained; otherwise, an attempt may be made to incrementally increase pump speed while monitoring for recurrence of drainage insufficiency. Of note, the pump speed should be maintained below the level where increases no longer result in higher flow rates.
Clinically evident etiologies for drainage insufficiency should be sought and addressed. For patients exhibiting agitation or coughing, treatment of the underlying cause should be considered; sedation may be required if its risks are outweighed by those of intermittent drainage insufficiency. Inspection of the ECMO circuit from the pump head to the cannula may identify tubing or cannula obstruction. Evaluation for occult bleeding, vasodilation, tension pneumothorax, cardiac tamponade, IAH, and cannula malposition should be performed as clinically appropriate.
For patients with ongoing drainage insufficiency, an assessment of fluid responsiveness should be undertaken. In volume responsive patients, Trendelenburg positioning may resolve drainage insufficiency and should be considered, as a temporizing maneuver, prior to fluid challenge. Subsequent resuscitation should be guided by clinical response, and once a volume replete state is achieved, fluid administration should cease.
If drainage insufficiency persists despite treating clinically evident etiologies and achieving a volume replete state, and assuming no occult cannula thrombosis, then the blood flow requirement is likely greater than can be achieved with the drainage cannula. In this case, placement of an additional drainage cannula should be considered.