3. PATIENT MANAGEMENT DURING ECLS
Setting up for ECLS
Cannulation for ECLS
Initiation of ECLS
Anti-coagulation
Initiation of ECLS
Laboratory studies
During transportation of the patient
Monitoring
Portable power supply
Advance planning
In the Intensive Care Unit
ECLS routine
Laboratory studies
Anti-coagulation
4. DISCONTINUATION OF ECLS
ECLS flow regulation
Anti-coagulation
Cannula removal
Selection of patients for ECLS can be extremely difficult. Favourable conditions need to be identified early before hypoxia has produced irreversible changes. The relative indications for use of ECLS must be based on the severity of the condition, the aetiology (including some knowledge of the expected time course of the disease and ECLS), and the availability of specific therapies.
| Disease | Description | ||||||||||||||||||||||||||||||||
| Viral pneumonia | Inflammation of the lungs caused by viral infection
| Aspiration pneumonia | Caused by aspiration of fluid into the lungs
| Mucoviscidosis | Fibroeystic disease of the pancreas; (cystic fibrosis)
| Septic lung | Severe, massive infection of the lung
| Traumatic pulmonary contusion | (Shocklung) Injury to the lung caused by trauma
| ARDS | One or more respiratory insufficiencies
| Pulmonary (fat-emboli) | Blockage of the pulmonary vasculature by fat
| Pulmonary bacteraemia | Disease of the lungs caused by bacteria
| Pulmonary burns | Caused by smoke inhalation, first and second degree
burns of the lungs due to inhalation of heat
| Heart and lung transplant | Support through severe rejection until new heart and
lung can be implanted
| Cardiogenic shock | Myocardial infarction with shock and post open-heart
surgery low-output syndrome (stunned myocardium)
| Malignant hyperthermia |
| Various shock syndromes |
| Metabolic acidosis |
| Various drug overdoses | Where the drug can be removed over time without
irreversible damage
| Accidental immersion |
| | ||
Where available the following items are required:
3. PATIENT MANAGEMENT DURING ECLS
Setting up for ECLS
Cannulation for ECLS
Several techniques for ECLS cannulation have been employed, but the most frequently used access
sites are the groin vessels in adults, and the common carotid artery and jugular vein in children and
infants. In adults the right common femoral vein and artery, when used, are usually cannulated both
proximally and distally to prevent oedema and ischaemia.
The perfusionist should be aware of the cannulation sites and the size of the cannula being used,
because maximum venous drainage is dependant on cannula size. The largest size cannula that can
be inserted should always be inserted, being aware of distal limb ischaemia.
The most commonly used form of cannulation for cardiac insufficiency is the venoarterial method
(ECLS). It effectively reduces high pressures in the right heart, whilst pumping enough oxygenated
blood into the aorta to maintain perfusion. This method will effectively perform the role of BVAD
as well as bypassing the lungs.
For respiratory insufficiency, veno-venous cannulation is preferred (ECMO). This allows for pre-
oxygenation of the venous blood prior to it entering the pulmonary circulation. This will directly
elevate the p02 of the blood returning to the left heart, and therefore the blood filling the ascending
aorta.
The proximal drainage cannula should be a thin wall type of about 23-27 Fr., and should be
threaded up as far as possible toward the right atrium to optimise drainage of cavoatrial blood with
the least possible resistance. The distal drainage cannula should be of the same type, possibly 10-12
Fr., to reduce venous stasis in the lower extremities.
The return cannula would be of about 15-19Fr gauge, either into the femoral artery or the internal
jugular vein, depending on whether venoarterial or veno-venous bypass was to be performed.
Initiation of ECLS
Anti-Coagulation
Immediately prior to cannulation, a loading dose of 10Ounits/kg, or 5000 units, whichever is less,
Sodium Heparin is given to the patient IV bolus. This will give enough anticoagulant protection to
see through the cannulation period, with cannula full of blood with no flow.
Following initiation of ECLS, no further heparin therapy should be required as long as there is
adequate flow, i.e. flow greater than 2.OLPM.
Regardless of the need or otherwise for anticoagulation, meticulous haemostasis is essential for
successful management of the patient on ECLS.
Initiation of ECLS
After cannulation and meticulous exclusion of air from the circuit, ECLS flow is gradually
increased while the RA pressure is monitored by a CVP line. The total systemic blood flow (native ventricular output + ECLS flow) is maintained at or above 2.4L/min/M2BSA. (Adequacy of total
systemic blood flow can only be assessed by ongoing and repeated blood gas analysis).
RA pressure is maintained in the 5-15mmHg range by volume adjustment. If venous chatter occurs
the RA pressure will need to be elevated with extra volume, regardless of the current pressure.
In order to assess the adequacy of these parameters frequent blood gas analysis must be performed, perhaps hourly for the first 6-12 hours then at least 4 hourly after that. As cardiac output detenninations will no longer be valid, acid/base status may be the only quantitative value to assess adequacy of total perfusion.
Laboratory Studies
The following list of lab work is ordered as soon as the decision is made to deploy ECLS:
| haemoglobin | haematocrit
| platelets | rbc
| wbc | fibrinogen
| fibrin degradation products | prothrombin time
| aptt | INR
| sodium | potassium
| chloride | bun
| creatinine | scrum osmolality
| free plasma haemoglobin | serum glucose
| total protein |
| |
During Transportation of the Patient
Monitoring
The patient must be appropriately monitored (ECG, arterial, LA and CVP pressures). Since the
initial period on ECLS may be very dynamic, adequate supplies for volume replacement (whole
blood, packed cells, FFP), should be available during transportation. A defibrillator and medication
infusion pumps are also required.
Portable Power Supply
A portable power supply for the Bio-Pump console is essential, and must contain enough power
reserve for the length of the anticipated trip. The handcrank should be available during
transportation in the event of a battery malfunction. Routinely, the Bio-Source External Battery
Pack should be available for any patient transfer.
Advance Planning
Advance planning as to the size of doorways, areas required to make turns around corners, width of
beds, length and width of elevators, etc, will save fi-ustration and time during the actual movement
of the patient. The patient will quite possibly be on the IABP as well as the ECLS, so that the space
required to move through the halls, doorways and into elevators is sometimes more than what is
available.
The Perfusion Services ECLS base or double-pump base will fit into a standard Victorian
Metropolitan Ambulance Service ambulance alongside the patient if the other bed is removed. (The
ECLS base must be placed on the lower side, that is the left-hand side of the vehicle).
In an extreme situation, the ECLS or double-pump base, along with the heater device, can be
removed to minimise size.
In the Intensive Care Unit
ECLS Routine
During an ECLS the patient is constantly attended by a perfusionist with a second perfusionist
available in the event of an ECLS system problem.
After arrival in the ICU the patient remains ventilated.
Continuous monitoring will include ECG to detect the presence of arrhythmias and to permit IABP
synchronisation, arterial BP, LA pressure or regular PCWP, CVP and, where possible, regular
cardiac output determinations.
Ideally during ECLS inotropic drugs are reduced to at most 500/o of maximum therapeutic levels,
and at best are ceased.
The systemic vascular resistance is maintained at 800-1200 where it can be measured. Antibiotic coverage is maintained during the ECLS period.
Laboratory Studies
The following list of lab work should be ordered as soon as practical after the patient is admitted to
the unit. The dynamic nature of the patient on ECLS requires that the lab work and results be
handled on a stat basis. The frequency of the lab testing is flexible to accommodate the changing
status of the patient and the regular workload of the laboratory, but should be no longer than 12
hourly.
| haemoglobin | haematocrit
| platelets | rbc
| wbc | fibrinogen
| fibrin degradation products | prothrombin time
| partial thromboplastin time | activated clotting time
| sodium | potassium
| chloride | bun
| creatinine | serum osmolality
| free plasma haemoglobin | serum glucose
| total protein | INR
| |
Anti-Coagulation
If a Carmeda heparin-bonded circuit, tip-to-tip, is being used for the ECLS then NO anti-coagulation is required for the ECLS.
If a non-bonded circuit is being used then the ACT is kept between 150-180 seconds using a
heparin infusion. ACT assaying is performed 1-2 hourly when anti-coagulation is used.
If the ECLS flow with either type of circuit requires being temporarily stopped (e.g. to change out a
component or piece of equipment), then heparin cover is required with a standard dose of 5,000
units of sodium heparin IV bolus.
Platelet transfusions are given to keep the platelet count above 100,000 and are often required daily
or even twice daily, FFP and clotting factors are given as required to achieve and maintain normal
coagulation.
Bleeding is a major potential complication for the patient on ECLS. Merely being on ECLS
will cause continuous fall in platelet number, decreased platelet function, and a general drift
toward coagulopathy. Attention must be paid to maintaining a normal clotting profile to
prevent bleeding, not wait for the problem and try to treat it.
ECLS Flow Regulation
Anti-Coagulation
Cannula Removal
The decision to discontinue ECLS is based on the status of the underlying pathology that indicated
the ECLS therapy in the first instance. The recovery of the patient's native pulmonary or cardiac
function can be assessed by weaning of the ECLS blood flow.
Weaning is generally not attempted during the first 24 hours. After 24 hours, if the patient's clinical
picture is stable, the ECLS blood flow is decreased to a level that causes the RA pressure to rise to
20-25mmHg. During this period the patient's arterial pressure waveform is monitored for signs of
ventricular ejection. (The PAP waveform is monitored for signs of right ventricular ejection). If
ventricular ejection is noted, cardiac output deterniinations are performed to assess the function of
the left ventricle. It is obviously imperative that ventilation is returned to adequate levels prior
to any decrease in ECLS blood flow.
If there is no ventricular ejection after one minute, the ECLS blood flow is returned to the previous
flow rate (native ventricular function may not return for two to three days).
Blood gas analysis from radial arterial blood should be performed after 2-3 minutes to assess native
respiratory performance. When native ventricular function is able to contribute at least one litre per
minute to the systemic blood flow, or the native respiratory function is able to function
satisfactorily, the ECLS blood flow is reduced accordingly.
The combined flows of the native ventricle and the ECLS pump should still deliver an index of at least 2.4L/min/M2BSA. In many cases this combined flow will only be able to be assessed for
adequacy by pH status.
Anti-coagulation is increased when the ECLS blood flow is decreased to one litre per minute,
typically the ACT is increased to 200-250 seconds. The assist flow rate is never decreased below
one-half litre per minute unless full systemic anticoagulation is instituted, regardless of the type of
circuit used.
A clotting profile should be obtained prior to the removal of the ECLS system, as administration of
clotting factors and / or red blood cells may be required.
When the attending physician, in consultation with the perfusionist, has decided that the native
ventricle can support the required cardiac output, or the native lungs have recovered enough for
sufficient gas exchange, the ECLS is terminated and the cannula are removed. This is usually
performed by open repair of the vessels under direct vision by a surgeon. This can be performed in
the ICU.