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The spokesperson for the Hong Kong Red Cross Blood Transfusion Service (BTS) made the following announcement on a rare blood transfusion reaction event today (September 4):
The BTS was informed by Prince of Wales Hospital (PWH) on August 21 that a 2-year-old girl with pancreatic tumour received a tumour resection procedure and blood transfusion on August 15. After the procedure, the patient presented with blood transfusion reaction symptoms of fever, low blood pressure, higher heart rate and skin rashes. The hospital treated the patient with a steroid, antibiotics and vasopressors. The treatment continued and the patient's symptoms gradually subsided. She is now asymptomatic and in stable condition.
The laboratory tests subsequently conducted by PWH isolated Pseudomonas fluorescens in the patient's blood and in her bag of blood. PWH immediately informed the BTS of the findings while at the same time traced the source of the blood bag. It was found that the blood bag concerned was delivered by the BTS to PWH on July 26. It was stored in the hospital blood bank until being transported to the operation theatre on the surgery day and used in transfusion about three hours later.
Afterwards, environmental samples were taken from the refrigerator and workstations of the blood bank in PWH, from the refrigerator at the operating theatre, and from the blood bag container. Random samples were also taken from the blood bags being stored in the same area at the blood bank. All these test results were negative for Pseudomonas fluorescens. Further environmental samples taken as a precautionary measure found traces of Pseudomonas fluorescens on the surface of an expired blood bag in the blood bank.
PWH has reported the case to the Hospital Authority (HA) Head Office through the Advanced Incident Reporting System. The hospital has explained the incident in detail to the patient's family and also extended its consolation to the patient. PWH will continue to provide the necessary care and treatment to the patient.
Upon receiving reports from PWH, the BTS initiated internal investigations in accordance with established procedures. The same batch of blood products including platelets and fresh frozen plasma has been used by other patients but no adverse reaction has been reported so far.
The BTS has reviewed all disinfection procedures of blood and blood products without finding any abnormality. Samples taken from the workstations found traces of Pseudomonas fluorescens in two samples. Like other common bacteria, Pseudomonas fluorescens exists in the environment and it is possible for it to be found on the surface of blood bags. However, the sealed blood bag and closed-system blood processing procedures ensure that bacteria cannot enter the blood bag.
The Chair Professor of Microbiology, Li Ka Shing Faculty of Medicine of the University of Hong Kong, Professor Yuen Kwok-yung, was invited to assist in reviewing the case. He pointed out that there was no conclusive evidence to explain how the Pseudomonas fluorescens entered the blood bag, while it was possible for the bacteria to enter the blood bag through invisible micro-cracks in the tubing attached to the blood bag. He pointed out that water condensate could form within 10 minutes on the surface of a blood bag after it is taken out from a refrigerator (temperature at 4 degrees Celcius) and placed in room temperature. He urged hospital blood banks to avoid unnecessary exposure of blood bags to room temperature.
According to medical literature, there are risks, though the rate is low, of infection associated with blood transfusion (red blood cells). It is estimated that the risk of infection ranges from 1:30 000 to 1:50 000, while transfusion reaction due to unfortunate incidence of infection is 1:500 000 with a mortality rate of 1:1 000 000.
Following a similar transfusion reaction incident a few years ago, the BTS has taken the following measures as recommended by an expert panel:
- All front-line staff must be equipped with a timing device to ensure that the stipulated skin disinfection timing complies with the required standards
- Ensuring all blood bag tubing is dry and free of visible surface condensation prior to thermal sealing and milking by strippers, and minimising manipulation of blood bags and tubing, except for the mandatory steps in processing and production, i.e. blood collection, component preparation, labelling and issue
- Redesigning packaging of blood units to minimise their exposure to condensate formed in foam boxes during transportation to hospitals
- Implementing additional stringent cleaning and disinfection procedures for all equipment used in blood collection, processing and storage (including the blood transportation foam boxes and refrigerators) and reinforcing training of front-line staff on these new procedures
- Implementing a surveillance system by using discarded blood units for bacterial culture and monitoring the outcomes
The BTS has in the past five years tested 1 405 units of expired red blood cell units and none of them were found to have bacteria. In investigating this incident, the BTS has randomly selected some red blood cell units for bacterial testing and all of them showed negative results. The BTS considers the reported incident a rare occurrence. As it is impossible to collect and process blood in an entirely germ-free environment, the BTS will continue to enforce the above-mentioned procedures. It has also immediately implemented a measure to minimise the risk of micro-cracks in blood bag tubing by reducing the need for front-line staff of hospital blood banks to manipulate the tubing. The BTS will seal the tubing into more segments before supplying the blood units to hospitals to facilitate the cross-matching procedure. Hospital blood banks are also reminded to avoid unnecessary exposure of blood bags to room temperature and to step up the monitoring of the blood processing procedures.
The HA Central Transfusion Committee has convened an ad hoc meeting to review and exchange views on this rare transfusion reaction event and to deliberate on safety measures to further reduce blood transfusion risks.
Ends/Wednesday, September 4, 2013
Issued at HKT 21:04
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