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Published on 1 January 2007

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Patient safety issues with X-ray contrast media

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David H Cousins
Head of Safe Medication Practice
National Patient Safety Agency
London
UK

Injectable medicines such as X-ray contrast media and heparinised saline may be removed from ampoules or vials and placed in an open and unlabelled basin in some clinical areas. Unlabelled syringes may be filled from these basins on several occasions during a clinical procedure. This is a high-risk practice and may lead to the administration of the wrong medicine or dose and the contamination of solutions.

Case study
A 69-year-old woman patient was admitted to a Seattle hospital in USA in 2004 for cerebral angiography to repair a brain aneurysm. During the procedure the patient was accidentally injected with an antiseptic solution of chlorhexidine in alcohol instead of contrast media. Both solutions were clear and available in the sterile field in unlabelled basins. Unfortunately, the chlorhexidine was drawn into the syringe and the patient received the antiseptic, which is highly toxic when injected intravascularly. Within two hours the patient suspected that something was very wrong. Acute, severe chemical injury to the blood vessels of the leg restricted circulation to the muscles, causing profound injury and swelling of her leg. During the following two weeks the patient’s condition deteriorated. She underwent a leg amputation and then suffered a stroke and multiple organ failure, which led to her death. Latent system failures that contributed to the incident included the use of open basins for intravenous solutions, the failure to label these basins and a recent decision to switch antiseptics from a brown povidone�iodine solution to a clear chlorhexidine in alcohol solution.(1)

Wrong drug or dose risks
Similar cases, following the use of open basins, have been reported where patients have received �gluteraldehyde, hydrogen peroxide and adrenaline.(2)

Findings from the 2004 ISMP (USA) Medication Safety Self Assessment, gathered from more than 1,600 hospitals, show that less than half (41%) always label containers (including syringes, basins or other vessels used to store drugs) in the sterile field, even when just one product or solution is �present. Eighteen percent do not label medications and solutions on the sterile field at all, and another 42% apply labels inconsistently.(1)

These findings concerning unsafe medication practices in X-ray areas are further supported in the sixth annual MEDMARX Data Report 2000-2004, which analysed 40,403 incident reports from hospitals and healthcare institutions across the USA.(3) The report examined in detail medication errors associated with radiological services at 315 hospitals and health systems, including procedures performed by radiology departments, cardiac catheterisation laboratories and nuclear medicine.

Of the errors reported by radiology services, 12% (242 of 2,030 reported between 2000 and 2004) were categorised as harmful errors; this was more than seven times the rate of harmful errors seen in the general MEDMARX dataset. The four leading types of radiological errors included wrong dose (28%), wrong drug (17%), omission of drug (17%) and prescribing errors (12%). X-ray contrast agents, anticlotting agents, sedatives and narcotics were classified as “high-alert medications” for radiology.(3)

Infection risks
There is some controversy concerning the infection risks for using open basins for injectable medicines such as X-ray contrast media solutions. Although there are no published case studies reporting patient harm from these practices, some research reviews the potential infection risk. One study evaluated the safety of the “open” method of contrast medium delivery in the angiographic theatre, in which the contrast medium was decanted into open basins on sterile trolleys. The air bacterial load within the angiographic theatre was sampled before and during angiographic procedures. The relationship of staff and patient activity to bacterial load was assessed. Samples of iopromide (Ultravist 370; Schering Pty Ltd, Sydney, NSW, Australia) were decanted into basins, and samples were taken for bacterial culture at the end of seven patient procedures. Air bacterial loads were comparable with operating theatre levels and were heaviest during staff activity.(4)

Three of seven samples taken at the end of angiographic procedures from air-exposed galley pots yielded contaminants, but the number of bacteria was below that required to produce septicaemia under normal conditions. The authors concluded that these results suggest that the open system of contrast medium delivery can be safely used, providing that bacterial checks of room contamination are performed and personnel entry into the theatre is strictly limited.

Research studies of contamination rates from repeated use of the same syringe have revealed that, as well as taking obvious precautions of avoiding contact with the needle or nozzle of a syringe, handling of the syringe plunger with repeated injections may allow bacteria to pass from the plunger to the syringe contents, and the single use of syringes is recommended to minimise bacterial contamination.(5-7)

Other studies have indicated the contamination rate of anaesthetic drugs by anaesthetists. Ten trainee anaesthetists drew up four syringes each of propofol, midazolam, thiopentone, sodium chloride 0.9% and a culture medium control using their normal practice. A set of syringes was cultured at the time of drawing up and at two, four and eight hours afterwards. No anaesthetist washed his or her hands before drawing up the drugs. Six anaesthetists capped the syringes using sheathed needles. Eight syringes were contaminated with bacteria. Coagulase-negative staphylococci were isolated from six syringes (four sheathed and two unsheathed) and Acinetobacter sp from two syringes (one sheathed and one unsheathed). No bacteria were cultured from the midazolam syringes. However, two syringes from each of the other solutions were contaminated. One syringe was contaminated when it was drawn up; at two hours a further two had detectable contamination, two more were contaminated at four hours and three more at eight hours.(8)

A study was undertaken to review contamination rates when nurses prepared 650 syringes from 10ml ampoules and 100 syringes from rubber-compound-capped 50ml vials in intensive care units in six hospitals. Turbidity of syringes after culturing for seven days at 37C was used as the criterion for possible bacterial contamination, which was proved with subsequent Gram staining. A median contamination rate of 22% (range 7-44%) was observed for the syringes prepared from 10ml ampoules by intensive care unit nurses. In more than 75% of all contaminated syringes, Gram-positive cocci were identified. At least 12% of all prepared syringes proved to be contaminated with staphylococci species. The contamination rate of syringes prepared from vials was much lower, at 2%. In the intensive care unit, standard procedures for preparing syringes for intravenous administration of drugs lack vigorous aseptic precautions, leading to a high contamination rate of the infusate. This risk is increased when ampoules instead of 50ml vials are used to prepare the syringes.(9)

Safer medication practice recommendations
The National Patient Safety Agency (NPSA) has been undertaking work to identify and minimise risks from injectable medicines in the UK. Draft safer practice recommendations were subject to stakeholder consultation earlier in 2006.(9) These recommendations included that a pharmacist and senior practitioner from each clinical area carry out a risk assessment of injectable products and practices at least once a year.

The NPSA has developed a risk assessment tool that can help identify high-risk injectable medicine products and practices. Measures that are recommended to improve patient safety include using closed systems rather than open systems, reinforcing and auditing policy that ensures that all syringes and infusions containing injectable medicines that leave the hands of practitioners are labelled and to minimise the use of concentrated injectable products that need dilution before use and to use ready-to-use products (eg, diluted solutions in ampoules and vials) and ready-to-administer products (eg, prefilled syringes) where these are available. The NPSA is planning to issue a Patient Safety Alert concerning the preparation and administration of injectable medicines in early 2007.

References

  1. Institute of Safe Medication Practices (USA). Medication Safety Alert 2004; December. Available from:http://www.ismp.org/newsletters/acutecare/articles/20041202.asp
  2. Institute of Safe Medication Practices (Canada). Safety Bulletin. Risk of tragic error continues in operating room. 2004; Available from: http://www.ismp-canada.org/download/ISMPCSB2004-12.pdf
  3. United States Pharmacopoea. Sixth Annual Medmarx Data Report.A chartbook of 2000�2004 findings from Intensive care Units and Radiokogical Services. 2006. Available from:http://www.usp.org/products/medmarx
  4. Tress BM, et al. Australas Radiol 1994;38:112-4.
  5. Bloog C, et al. Br J Anaesth 1974;46:260-2.
  6. Percival A. Med J Aust 1980;17:487-9.
  7. Huey W, et al. Am J Hosp Pharm 1985;42:102-5.
  8. Magee L, et al. Eur J Anaesthesiol 1995;12 Suppl:41-3.
  9. Van Grafhorst JP, et al. Crit Care Med 2002;30:833-6.
  10. National Patient Safety Agency. Stakeholder consultation on safe use of injectable medicines. January 2006. Available from: http://www.npsa.nhs.uk


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