Medicines Healthcare Products Regulatory Agency
Date of Issue: 4 April 2024
Reference No: NatPSA/2024/004/MHRA?
This is a safety critical and complex National Patient Safety Alert that is relevant across many departments and professions. Implementation should be coordinated by an executive leader (or equivalent role in organisations without executive boards) and supported by their designated senior leads for medical, nursing, midwifery, scientific and allied health professionals.
Explanation of identified safety issue
Transfusion-associated circulatory overload (TACO) is defined as acute or worsening respiratory compromise and/or acute or worsening pulmonary oedema during or up to 12 hours after transfusion, with additional features including cardiovascular system changes not explained by the patients underlying medical condition, evidence of fluid overload and a relevant biomarker. TACO is one of the most common causes of transfusion-related deaths in the UK and cases have increased substantially in recent years. Identifying risk factors for TACO prior to transfusion allows initiation of appropriate mitigating measures[footnote 1].
TACO deaths are potentially preventable. TACO can occur in any individual of any age, including elderly people, children, and neonates. The risk is increased by the following factors:
- cardiac dysfunction
- renal dysfunction
- low body weight
- hypoalbuminaemia
- pre-existing fluid overload
- high volume in relation to body weight
- severe chronic anaemia
- women with severe pre-eclampsia
Non-bleeding adult patients with severe chronic anaemia are particularly vulnerable to risk of TACO. Errors in prescription for blood components have been reported in children and can contribute to TACO. Pulmonary complications of transfusion within this group can be difficult to identify, particularly in neonates. There should be awareness of TACO as a potential cause of respiratory deterioration following transfusion in this group.[footnote 2],[footnote 3]
TACO risk reduction measures include:
- avoiding unnecessary transfusions
- single-unit transfusion or transfusing only the minimum number of units (or weight-adjusted red cell dose) needed to meet the haemoglobin (Hb) target (using red cell calculator[footnote 4]) and assessing response
- consideration of weight-adjusted red cell dosing for patients of low body weight (including children)
- avoiding transfusions in excess of recommended infusion rates
- administering a diuretic when appropriate
- monitor vital signs closely, including oxygen saturation
Further supporting information about TACO and this alert can be found in the supporting FAQ document[footnote 5].
Actions to be completed as soon as possible and no later than 4 October 2024
1. Review and update policies, procedures and processes to ensure:
a. All transfusions are compliant with recommendations from British Society for Haematology (BSH),[footnote 6] [footnote 7] SHOT,[footnote 8] and NICE[footnote 9]
b. A TACO risk assessment is undertaken utilising the SHOT risk assessment tool[footnote 1] prior to transfusions*
c. Appropriate mitigation measures are initiated for individuals at risk see FAQ document[footnote 5]
d. Patients and carers should be informed of TACO as a significant potential complication of transfusion and likely symptoms, as part of complying with Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) consent for transfusion guidance[footnote 10]
e. Inclusion of guidance on timely management of TACO, including the use of diuretics, oxygen, and other supportive measures
f. Clear communications on discharge to patients and staff involved in the care of the patient about blood components and/or blood products administered and any complications such as TACO
g. Use of the structured TACO incident investigation tool[footnote 11] from SHOT
2. Review, update, and implement training programmes to include:
a. Use of TACO pre-transfusion risk assessment tool*
b. Appropriate use of mitigation measures FAQ document[footnote 5]
c. Management of severe chronic anaemia in non-bleeding patients using minimal/single-unit transfusion support, and anaemia management with iron therapy where appropriate
d. Recognition and prompt management of TACO, importance of timely interventions and escalation of care as appropriate
e. Empowerment of clinical staff and biomedical scientists to question practices of prescribing/requesting blood components
f. A process for recording participation and identifying dates for re-training
g. Knowledge and awareness to report TACO cases locally, as well as to MHRA and SHOT by hospital transfusion teams
3. Undertake regular audit on the use of the TACO risk assessment tool for adult patients*, consent practices, management of chronic severe anaemia, avoidable transfusions, volume of red cell transfusion and communication of information at discharge to relevant teams involved in the care pathway including patients
*It is important to note that the TACO risk assessment tool has not been formally validated for paediatric age groups, but the risk factors are similar. Careful attention to appropriate volume and rate of transfusion is vital.
Additional information
Further information and patient safety incident data
The MHRA are regulated by the Secretary of State to collect information regarding Serious Adverse Reactions (SAR) under Sections 7 (e) (ii), for Blood Establishments and, Section 9 (f) (ii), for Hospital Blood Banks under the Blood Safety and Quality Regulations 2005 (as amended). SHOT provide the MHRA with consultant clinical input to ensure the correct classification of SARs, including TACO.
Review of TACO events analysed by SHOT between 2010 and 2022 found a total of 1336 reports. In this 13-year period, TACO contributed to 111 deaths, accounting for 39.2% (111 in 283) of all transfusion-related deaths reported to SHOT. The increasing trend in patient deaths and major morbidity due to TACO, with 8 deaths and 25 patients with major morbidity in 2022[footnote 8], prompted this safety alert. In 2022, there were 3 cases in the under-18 age group, including neonates[footnote 8].
The use of a formal pre-transfusion TACO risk assessment was introduced in the 2015 Annual SHOT Report [footnote 12]. A question regarding the use of the TACO risk assessment and mitigating actions was added to the SHOT questionnaire for the 2019 reporting year. In?2022, the TACO risk assessment was not used in 60.6% (97 in 160) of reported TACO cases. Where a TACO risk assessment was performed in 29 of 57 (50.9%), the need for a mitigating action was demonstrated. In most cases, appropriate actions were taken, however, in some cases additional measures could also have been performed.
Severe anaemia was added to the TACO risk assessment following evidence emerging in the data [footnote 13]. Non-bleeding adult patients with severe chronic anaemia are particularly vulnerable to TACO, even in the absence of additional risk and comorbidities known to predispose to TACO. From the 2022 SHOT data, 39 of 160 cases had Hb lower than 60gL; of these 39 cases, 7 were of severe anaemia due to haemorrhage or erroneous Hb measurement, 32 had severe chronic anaemia and 7 of these had clear evidence of iron deficiency.
The TACO structured investigation tool was first launched in the 2020 Annual SHOT Report and continues to be a recommenda