INFORME Nº 038-2008-SUNAT

a. SIG Alarm (loss of flow signal) Rotaflow/PLS platform: This is due to the loss of the ultrasonic

flow signal on the Rotaflow pump – usually due to inadequate coupling interface between the ultrasonic flow sensor and the ECMO circuit. It does not occur on the Cardiohelp system. The blood flow reading disappears or is intermittent with a “SIG” flashing signal. Pump function does not change and will continue to run. Bedside staff may re-establish the flow signal electively when it is safe to do so

i. Re-establishing the flow signal during patient support:

a. The patient is changed to 100% Oxygen via the lungs (5min) b. Circuit is clamped (post oxygenator)

c. Speed setting is immediately turned to 0 RPM d. Ultrasound cover is opened

Prompt Doc No: <#doc_num> v<#ver_num> Approval Date: Nov 2012 Review & Update by: Nov 2015 e. Pump head is removed

f. The contact “cream” is applied to the ultrasound windows just distal to the pump head g. The pump head is re-inserted with the leading edge place under the locating pin and

the ultrasound cover is latched

h. The speed setting is returned to approximately 1000 RPM and the clamp is slowly removed (over 3-5 sec) while the speed setting is gradually increased until desired flows are achieved

b. Flow Sensor Management Cardiohelp/HLS platform: The flow sensor for the Cardiohelp does

not require any contact “cream” (coupling medium). The sensor is clipped on to the return side (post oxygenator) of the circuit tubing with the flow sensor arrow facing in the direction of flow (away from the oxygenator). Disconnection of the flow sensor during use will result in the loss of signal. Reconnection in the opposite direction will result in a negative flow reading. If Flow

Interventions are enabled this will result in an attempt to reverse flow in the circuit. For this reason the Flow Intervention function should not be enabled in the Alfred ICU

c. The Cardiohelp Flow Sensor also has an integrated bubble sensor: Bubble alarms should be

reported to medical staff and the circuit checked for visible signs of air bubbles. Bubble Interventions must not be enabled during patient care in the Alfred ICU

d. Low Flow Alarms: Low flow alarms indicate that flow has fallen below the set alarm limit. It must

prompt an immediate search for possible causes. Flow is determined by load and speed settings. Treatment is determined by the cause

i. Common causes and features of low flow alarms

a. Speed setting changed: Speed setting has been lowered and alarms have not yet been adjusted.

b. Access insufficiency (see below): Flows should improve with a reduction in the pump speed setting

c. Kinked or twisted circuit tubing: Visible problem corrected immediately when tubing is straightened

d. Oxygenator occlusion: Falling blood flow with rising trans-oxygenator pressures. Does not improve with a reduction in pump speed

e. Patient bleeding: Presents as access insufficiency (see above). Whenever access insufficiency is encountered, consider the possibility that the patient may be bleeding (even if this is not immediately evident)

f. Air embolism: Visible air in the circuit and pump head.

g. Significant elevation in blood pressure (VA ECMO only): Associated with an obvious change in recorded blood pressure and clinical state e.g. waking up, coughing, straining

e. Access insufficiency – Definition and Features: This is a state where the suction pressure at

the access cannula is excessive for the venous return and inflow is interrupted by intermittent or partial occlusion of the inlet ports on the access cannula by the walls of the collapsible vein. Features depend on the severity, the type of access cannula (see Section 3) and the equipment platform. Commonly, features include variable or falling blood flow with or without visible and palpable access line movements.

i. Single stage cannulae produce obvious visible and palpable “shaking” or “chattering” of the circuit tubing draining to the pump; high variation in the measured flow; and falling average flow. Blood flow will fall further and line “chattering” will worsen if pump speed is increased. Line “chattering” will stop in response to a reduction in pump speed.

ii. Multi-stage cannulae may demonstrate partial occlusion of the cannulae access holes without any visible or palpable line movement. Blood flow may fall and will not increase if speed is

increased. In VA ECMO, pulmonary or aortic pulsatility may be lost as the right side of the heart is “sucked-down”. Definitive diagnosis requires echocardiography.

iii. The Cardiohelp/HLS system incorporates negative access pressure (pre-pump head) monitoring. Negative pressures usually increase before access insufficiency is clinically evident. Increasing negative pressures associated with stable or falling blood flow indicates early access insufficiency

f. Access Insufficiency Causes and Treatment: Access Insufficiency is caused by inadequate

venous return relative to the degree of negative access cannula pressure i. Common causes

a. Hypovolaemia/Bleeding

b. Poorly sited access cannula (too low)

c. Cardiac tamponade (common post sternotomy) d. Excessive RPM setting

e. Patient coughing or straining f. Positional (after turning the patient) g. Acute vasodilatation (sedation bolus) h. Increased intra-abdominal pressure

i. Severe aortic regurgitation / fatal pulmonary haemorrhage (VA ECMO)

ii. Immediate treatment is to reduce the speed setting until features disappear whilst attempting to maintain adequate patient support. If former pump speed settings cannot be re-established, then a bolus of fluid should be administered. Repeated episodes should not be treated with fluid, as massive volume overload/oedema will arise. Cardiac tamponade must be excluded or treated. Additional access cannulae may be required to access sufficient venous return after bleeding and cardiac tamponade have been excluded

g. Circuit and oxygenator changes: These are most commonly required for aged circuits (generally

2-3 weeks of age) where clot accumulation causes coagulation system activation and

inflammation. The cardinal features are rising D-Dimer with falling fibrinogen (< 2). It is very rare for oxygenators to malfunction and fail to oxygenate blood sufficiently, however, a post-oxygenator PaO2 below 200mmHg should lead to an elective circuit change-out. Rarely, circuits may need to

be changed urgently for pump head or oxygenator thrombosis

h. CRRT (Prismaflex) pressure alarms: High ECMO circuit pressures can result in CRRT high

return positive pressure alarms. High ECMO circuit pressures are expected with higher blood flow rates and with the use of smaller ECMO return cannulae (e.g. VA ECMO with 15F return cannula; or dual-lumen, bi-caval (Avalon Elite) VV ECMO. Higher CRRT blood flow settings will also be expected to raise the pressure in the CRRT return circuit.

i. CRRT High pressure alarm management on ECMO: a. Reduce CRRT blood flow (if possible) b. Reduce ECMO blood flow (if possible)

c. Replace ST 100 set with ST 150 set (Contact ECLS Co-ordinator or Equipment Nurse)

d. PLS: Change CRRT return port to post-oxygenator connection port e. HLS: Swap CRRT access and return

f. Consider non-ECMO site for CRRT return (e.g. large bore peripheral cannula) g. Consider inserting separate vascath

i. Pneumothorax on VV ECMO: Pneumothoraces, particularly early in the course of ECMO for

respiratory failure, MUST NOT be drained unless they cause tension resulting in haemodynamic compromise. Further reductions in lung ventilation (and increased ECMO support) may control or reverse air leaks and allow inter-costal catheters to be avoided, or inserted later when lung injury is

Prompt Doc No: <#doc_num> v<#ver_num> Approval Date: Nov 2012 Review & Update by: Nov 2015 less severe. Traditionally the commonest mode of death on VV ECMO support was bleeding and the most common site was pleural space bleeding related to inter-costal catheter insertion.

j. Cannula site bleeding: Cannula site bleeding: This is preventable by using meticulous sequential

dilatational technique during percutaneous cannula insertion and carefully securing the cannulae to prevent migration. Most commonly, cannula site bleeding is due to an arterial return cannula partially “sliding out”, leaving a narrower part of the cannula at the arterial entry point. Evaluation of arterial cannula site bleeding must include vascular ultrasound to exclude vessel injury, which will require vascular surgical input.

i. Management options include:

a. Fully inserting the cannula to the taper b. Thrombotic (Kaltostat) dressings c. Pressure (sand bag)

d. Cessation of heparin e. Vascular surgical review f. Repair and re-cannulation

ii. “Purse-string” suturing should NEVER be attempted by ICU staff due to the risk of vessel or cannula damage and delayed skin necrosis which will complicate any eventual repair