Table 1.

Procedures and measurements

	Day 0–7 before start therapy	3 hours after start sildenafil	12 hours after start	8 am after start	24 hours after start	Day of surgery, preoperatively	Day after surgery	Day of ECMO, pre- cannulation	8 am after start ECMO	Day 14	Day 28/before discharge	Day 56	6 months	12 months
Echocardiography	X				X					X	X		X	X
Calculation OI	X		X		X
Calculation VIS score	X		X		X
Blood sample	X			X		X	X	X	X	X
Tracheal aspirate	X			X		X	X	X	X	X
Urine sample	X			X		X	X	X	X	X
Severity of CLD											X	X
Ultrasound brain	X						X
Sildenafil plasma level		X		X		X	X		X

CLD, chronic lung disease; ECMO, extracorporeal membrane oxygenation; OI, oxygenation index; VIS, vasoactive-inotropic support.