Cannulation and ECMO initiation-
Femoral-femoral veno-venous ECMO cannulation was performed by the
cardiac surgeon in the ICU under trans-esophageal (TEE) guidance by
cardiac anesthesia. Full personal protective equipment was worn by all
members of the health care team within the room. Additional
precautionary measures included limiting the number of health care
workers within the patients’ room during cannulation. The institutional
cannulation heparin bolus dose for VV ECMO was increased from 50u/kg to
100u/kg or more after the initial patients formed significant thromboses
despite heparin anticoagulation. Cannula included a Edwards ThruPort™
Quick Draw™ (Irvine, CA) 25Fr multi-stage femoral venous drain with the
distal tip positioned at approximately the hepatic vein - inferior vena
cava junction, and a Medtronic Bio-Medicus™ NextGen (Minneapolis, MN)
19-21Fr return cannula with the tip placed within the right atrium. ECMO
equipment consisted of either a Rotaflow centrifugal pump (Getinge AB,
Getinge, Sweden) with a Quadrox iD Adult oxygenator or a CARDIOHELPi
system (Getinge AB) with HLS Set Advanced 7.0. ECMO blood flow was
maintained > 3 L/min to help minimize the identified risk
of thrombosis.
Following cannulation, patients were placed on an ultra-protective
ventilator strategy that included a graded reduction in plateau pressure
to < 20 cmH2O over the next 12 hours. Tidal
volumes were reduced to < 4ml/kg IBW and the
FiO2 was reduced to 60% if the patient was able to
maintain an acceptable oxygenation status. Positive end expiratory
pressure (PEEP) was slowly reduced to a level of 10 -
14cmH2O. Higher levels of PEEP were required in patients
with high BMI’s. Respiratory rate was maintained at 8 - 10
breaths/minute for the initial 24 hours. In Covid-19 patients with the
lung phenotype characterized with increased compliance, higher tidal
volumes, and respiratory rates were tolerated as the patients started to
improve (10). In addition, patients with bilateral infiltrative disease
that did not improve after fluid removal and lung rest underwent a
16-hour prone positioning plan (Figure 2). Seven of the fifteen patients
managed on ECMO were placed into a prone position at least once, with
the majority in prone position multiple times. Mobility was gradually
enhanced from a bed tilt of 30-45 degrees to as high as standing
(vertical) positioning via a specialty bed (Kreg Medical, Inc. Chicago,
IL) (Figure 3).