Results
During the study period, there were 181 patients treated with ECMO, of
which, 72 had cardiovascular failure and were treated with VA ECMO. Of
these, 14 patients were placed on VA-V ECMO. At our institution, all
patients on VA ECMO receive a right radial, brachial or axillary artery
catheter for blood gas sampling (except for patients who have a right
axillary side-graft for reinfusion). There were more males (11/14, 79%)
than females in this cohort. Their median age was 54 (range 18 – 75)
with median BMI of 30.3 (range 25 – 54). Patient characteristics are
summarized in Table 1 .
Underlying diseases included myocardial infarction (4/14), cardiac
arrest (3/14, two with concurrently diagnosed pneumonia [PNA]),
pulmonary embolism (2/14), anti-hypertensive overdose (2/14, one with
coexisting pneumonia), decompensated pulmonary arterial hypertension
[PAH], penetrating chest injury, and postpericardiotomy syndrome.
Seven patients (50%) were transferred to our institution for ECMO,
while 50% (7/14) of patients suffered pre-ECMO cardiac arrest. Our
study population had a median SOFA-0 score of 15 (predicted ICU
mortality of 95.2%) and the last arterial blood gas prior to ECMO
cannulation had a median pH of 7.20,
PaO2/FiO2 ratio of 73, and
PaCO2 of 50; one patient did not have a documented ABG
prior to cannulation. Five patients had a left ventricular ejection
fraction ≤ 30% on pre-ECMO echocardiogram, and five patients had
moderately or severely reduced right ventricular ejection fraction
(RVEF); two patients did not have a documented pre-ECMO transthoracic
echocardiogram (TTE), and the RVEF of two patients was not assessed due
to technical limitations.
Underlying disease, initial ECMO indication, and indication for VA-V
conversion are displayed in Table 2 . Seven (50%) patients were
initiated on VA ECMO with a median SAVE score of -12 (risk class V,
predicted in-hospital survival of 18%), and the remaining seven
patients were placed directly on VA-V ECMO due to present or imminent
combined cardiopulmonary failure. The majority of patients initially
cannulated on VA ECMO were quickly transitioned to a VA-V configuration,
however three patients were on VA ECMO for a significant amount of time.
None of the patients in our study population were initiated on a
veno-venous configuration. Sequence of ECMO configurations with cannula
size and locations are shown in Table 3 . Two patients were
cannulated at outside hospitals prior to transfer, and the cannula sizes
for one of these patients were not documented in our EMR. A superficial
femoral artery distal perfusion cannula was placed in 9 of 13 (69%)
patients who were cannulated via the femoral artery, and four patients
(29%) had an Impella in place while on ECMO.
Arterial blood gas data is shown in Table 4 . On Day 1 of ECMO,
our patients had a median PaO2 of 271 on a median ECMO
flow of 4.22 L/min. Indications for VA to VA-V conversion included
differential hypoxemia (5/7, 71%), persistent hypoxemia, and
respiratory failure secondary to diffuse alveolar hemorrhage.
ECMO adjuvants, anticoagulation strategy, and blood product
administration are shown in Table 5 . One patient was only
anticoagulated with Impella purge solution, eight (57%) received a
heparin infusion, and five (36%) were placed on Argatroban infusion
(two of these patients were transitioned from heparin due to concern for
HIT). Anticoagulation was held due to bleeding in 79% (11/14) of
patients at some point in their ECMO run, and a median of 7.5 units of
PRBCs and 2.5 units of platelets were transfused while on ECMO.
Of the 11 patients that demonstrated cardiac and pulmonary recovery
allowing for weaning of ECMO support, eight (73%) were transitioned to
VV prior to decannulation and three (27%) were decannulated directly
from VA-V. The first arterial blood gas following ECMO had a median pH
of 7.39, PaO2/FiO2 ratio of 262, and PaCO2 of 49. Six of eleven patients
had documented post-ECMO transthoracic echocardiograms, which are shown
in Table 6 .
Complications are listed by subcategory in Table 7 . In order of
frequency, these included acute kidney injury (93%), clinically
significant bleeding (50%), thrombotic non-circuit (36%), limb
ischemia (36%), infection (29%), neurologic (29%), and
mechanical/circuit (14%). Two patients with limb ischemia required
intervention: one patient required bilateral below knee amputation and
another with SFA occlusion required thrombectomy. All 4 infectious
complications were due to pneumonia. With regards to neurologic
complications, 2 patients had embolic strokes and 2 patients developed
anoxic brain injury. Additionally, mechanical/circuit complications
occurred in 2 patients: 1 patient had oxygenator fibrin accumulation
requiring circuit exchange, and another had distal perfusion cannula
clotting that required catheter exchange.
Patient outcomes are listed in Table 8 . VA-V support was
utilized for 92.4 out of 148.2 total ECMO hours (median values with
first and third quartiles displayed). Causes of death on ECMO included
cor pulmonale, asystolic cardiac arrest, and withdrawal of care due to
persistent cardiogenic shock as well as ARDS with severe hypoxic
respiratory failure. Two patients did not survive from decannulation to
discharge due to respiratory failure and withdrawal of care in the
setting of anoxic brain injury. A total of 79% (11/14) of patients
survived to ECMO decannulation and 64% (9/14) survived to hospital
discharge, with 82% of decannulated patients surviving to discharge.
One patient was transferred back to their original hospital and the
remaining patients were discharged to an extended care facility (11%),
physical rehabilitation facilities (33%), or home (44%). Cumulatively,
these patients spent a median of 12.5 days on a ventilator, 14.5 days in
the ICU, and 22 days in the hospital with a median of 12 ventilator
free, 28.5 ICU free, and 1.5 hospital free days in 60.