Overnight transfusions in New Zealand hospitals: potential risk to patients

This audit aimed to assess how frequently overnight transfusions were taking place and compare it to the previous 2004 audit.

All red cell units transfused between 20:00 and 08:00 hours in low acuity areas over 4 weeks in 2010 in 8 of New Zealand's largest public hospitals were identified prospectively, followed by review of clinical notes and laboratory results by the hospital Transfusion Nurse Specialist (TNS).

535 red cell units were transfused overnight, or 9% of the total units administered over the study period. Indications for transfusion were symptomatic anaemia, active bleeding or haemolysis (66%), but 16% of patients were asymptomatic. Of the non-urgent overnight transfusions (OTs), 42% were assessed as non-essential during the night. 49% of post-transfusion haemoglobin (Hb) levels were >100 g/L indicating a liberal transfusion practice. Although frequently cited as a reason for OT, only 16% of patients were discharged the following day. The median interval from pre-transfusion haemoglobin testing and starting the OT was approximately 9 hours, far exceeding the time needed to obtain routine full blood results. Adherence to recommended best transfusion practice was poor at night, with 12% of transfusions exceeding the 4 hour recommendation. End of transfusion observations fell to less than 80%, with the lowest compliance rate (69%) occurring at 06:00 hours. In addition to the 4 adverse reactions reported to the Haemovigilance programme, another 9 unreported reactions were identified by the auditors from the clinical notes.

This audit has shown an improvement from 22% to 9% in the rate of OT compared to the 2004 audit. Nevertheless, 42% of transfusions were not considered appropriate based on current guidelines, and there is therefore room for improvement. A mean delay of 9 hours from haemoglobin sampling to transfusion suggests that reasons for this delay could be explored to help optimise transfusion start time. Some aspects of OT were worse than previously, with 12% of the OT exceeding 4 hours duration, double the rate of the previous audit. Results showing poor documentation and a high rate of unreported transfusion reactions (69% of reactions) suggest if an adverse transfusion reaction occurs overnight, there is a significant risk that it is less likely to be recognised, treated and/or reported.