Transcranial Doppler is an effective method in assessing cerebral blood flow patterns during peripheral venoarterial...

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) can be life-saving in refractory cardiogenic shock but carries a risk of neurologic complications such as stroke and hemorrhage. As little is known about the effects of different peripheral VA-ECMO cannulation sites on cerebral blood flow (CBF), transcranial Doppler (TCD) was used to determine whether the cannulation site affects CBF.

Thirty-seven patients receiving VA-ECMO for cardiogenic shock via axillary or femoral artery cannulation were prospectively enrolled. Measured bilateral middle cerebral artery (MCA), mean flow velocities (MFV), and pulsatility indices (PI) were the primary outcomes and adverse neurologic events were secondary outcomes.

The median age was 58 years (IQR 51-66) with 26 (70%) males. Median VA-ECMO flow was 3.8 L/min (IQR 3.2-4.9) with mean arterial pressures of 80 mm Hg (IQR 75-86). Nineteen patients received right axillary artery cannulation while 18 underwent femoral cannulation. Compared with the femoral group, MFV was higher in the axillary group in the right MCA (46 cm/s [IQR 26-57] vs 27 [17-36], P = 0.03) and left (43 [IQR 35-60] vs 29 cm/s [16-48], P = 0.05). Axillary PI was significantly lower compared with the femoral group (right: 0.48 cm/s [0.25-0.65] vs 0.83 [0.66-0.93], P = 0.02; left: 0.41 cm/s [0.29-0.63] vs 1.02 [0.7-1.3], P = 0.004). One axillary patient experienced a stroke with deficits.

TCD appears to be an effective tool for indirect monitoring of CBF in patients with ECMO with limited pulsatility. Axillary artery cannulation seems to provide higher cerebral flow rates without any difference in neurologic outcomes. Future studies may incorporate TCD into regulating ECMO flows to achieve physiologic CBF.