A detailed listing of the alarms can be found in the Rotaflow manual, page 50. The essential alarms and their clinical implications are summarised below.

Low flow alarm

The low flow alarm indicates 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 depending on the cause. Common causes and features of low flow alarms include the following:

  • Important to identify access insufficiency as a cause of low flow alarm. Flows should improve with a reduction in the pump speed setting. Note: kinked or twisted circuit tubing correct flow immediately when tubing is straightened

All other causes of low flow alarm do not improve with a reduction in pump speed

  • Speed setting changed: speed setting has been lowered and alarms have not yet been adjusted.
  • Oxygenator occlusion: falling blood flow with rising trans-oxygenator pressures.
  • Air embolism: visible air in the circuit or pump head. Clamp circuit immediately.
  • Significant elevation in blood pressure (VA ECMO only). The rise in afterload leads to a reduction in flow e.g. in the setting of waking up, coughing, straining or after a bolus of vasopressors.

SIG alarm

[SIG] Alarm (loss of flow signal) only on Rotaflow 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 the circuit will continue to run. Bedside staff may re-establish the flow signal electively when it is safe to do so

Re-establishing the flow signal during patient support:

  • The patient is changed to 100% Oxygen via the lungs (5min)
  • Circuit is clamped (post oxygenator)
  • Speed setting is immediately turned to 0 RPM
  • Ultrasound cover is opened
  • Pump head is removed
  • The contact “cream” is applied to the ultrasound windows just distal to the pump head
  • The pump head is re-inserted with the leading-edge place under the locating pin and the ultrasound cover is latched
  • The speed setting is returned to approximately 1500 RPM and the clamp is slowly removed (over 3-5 sec) while the speed setting is gradually increased until desired flows are achieved

Flow sensor not reading

Specific to Rotaflow Platform

In case of loss of flow signal

If the pump is functioning normally see SIG alarm above or if occurring during start-up apply more ultrasonic cream at the flow meter. Commonly a generous application of the Ultrasound contact cream is required in these circumstances.


[LOW BAT] Continuous battery alarm

This alarm cannot be turned off. It occurs at 20V. You need to act.

  • Re-establish AC power checking: wall connection, circuit plug behind the console, power cord connection
  • If no resolution change console emergently

At 19.0V the system switches off, so you only have very limited time.

Tip: always check that the battery charging light comes on when connecting a console to power. This will ensure the battery is fully charged when required.

The routine Battery Alarm (display [BAT] and voltage e.g. 24.5) will get activated with every disconnection from the main power. It is important to check the battery charge status after disconnecting the console from the main power source. Note: it may drop over several minutes and should remain >24V.

In case of battery failure, the console will stop.

  • Commence Manual Cranking and call for help
  • Re-establish AC power checking: wall connection, circuit plug behind the console, power cord connection
  • Prepare for a Console change

Replace battery

  • Routine every two years
  • If unable to fully charge within 8.5 hours
  • If only lasts 30min (fully charged)


Flow and bubble sensor

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

Cardiohelp Flow Sensor and 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. Resetting the bubble alarm is required, it is quite common after initiation to alarm from a residual microbubble that may come from the oxygenator.

Screen failure

In case of screen malfunction, any operations via the touchscreen won’t be possible. This may occur with mechanical destruction of the screen or electronic failure.

Switch to Emergency Mode as shown below in the video below by activating the Emergency mode.


Please note: in the Emergency mode ALL alarms are deactivated. Ongoing clinical monitoring is required if the console cannot be exchanged.

Backflow prevention

The Backflow prevention can detect and react to backflow of blood in the circuit. The console will alarm and activate the “zero flow mode” automatically, aiming to reverse any negative flow readings. It will rapidly increase the RPM (even up to 5000 RPM) aiming to achieve this.

Caveat – The machine can not differentiate a reverse placement of the flow meter from true ‘backflow’ in the circuit. The operator is required to identify the misplaced flow meter. The backflow prevention can not be turned off but is inactivated when global override is turned on.


All interventions need to be turned off, this is part of the nursing checklist. The machine monitors different parameters and displays alarms. Under set conditions it can intervene. Interventions are triggered under certain pre-defined conditions. Whilst different parameters can be set, the interventions, however, may include stopping the pump and can not be changed. Global override does override intervention, but only whilst it is on.


To fully charging the battery will take up to 7 hours.

Once capacity drops below

  • <20% – medium priority alarm (3 alarm tones)
  • <10% – high priority alarm (2x 5 alarm tones, disabling is not possible)

Heater unit alarms

Water level

If the water level falls below the minimum value on the display the alarm ‘WATER LEVEL!?’ will appear. Silence with the ‘Alarm Off’ key, stop the unit and fill with sterile water to 70-80%, remember the volume form minimum to maximum water level is 0.7 L.

Temperature below 32°C

Shown as ‘TEMP <32°C’ a measured temperature of below 32°C during operation will result in this alarm, silence with ‘Alarm Off’ key for 10 minutes.

Temperature difference >1°C

Shown as ‘TEMP.DIFF>1°C’ will alarm whenever the temperature of returning heater water differs more than 1°C from the setpoint for a prolonged period. The alarm can be silenced for 10 minutes with the ‘Alarm Off’ key (see temperature management).

Temperature >40°C

The alarm message ‘TEMP>40°C’ will be displayed and will automatically switch off the unit. Check the patient’s temperature if the temperature is factually high revert to standard cooling measures for the patient otherwise if alarm re-occurs check unit for any fault.

Alarm during performance test

If during startup the alarm ‘ALARM TEST FAIL – CALL SERVICE’ appears the unit will automatically switch off. It may be tried again after 1-2 hours, if unsuccessful the unit needs to be checked by the manufacturer’s service.

CRRT pressure alarm

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