Anaesthesia 2014, 69, 78–91
Correspondence
Table 1 Effect of contamination on blood sample biochemistry. The volume of blood (X, above) is 0.96 ml and that of flush (Y, above) is 0.4 ml.
Glucose; mmol.l1 Sodium; mmol.l1 Chloride; mmol.l1 Potassium; mmol.l1 Hydrogen ion; nmol.l1 pH
A
B
F
Concentration or value in blood
Concentration or value in flush contaminant
Final concentration ((A 3 X) + (B 3 Y)) or value
5 145 100 5 40
280 154 154 0 3160
16 145 102 4.8 165
7.4
5.5
6.8
As we emphasised in our paper, sodium chloride 0.9% with glucose 5% appears to be a particularly dangerous fluid in these circumstances. It has the capacity to be readily mistaken for sodium chloride 0.9% and a high enough glucose concentration to lead to markedly elevated glucose levels with very low levels of sample contamination. Other blood biochemistry is highly unlikely to be dramatically altered. T. M. Cook K. J. Gupta Royal United Hospital Bath, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
Reference 1. Gupta KJ, Cook TM. Accidental hypoglycaemia caused by an arterial flush drug error: a case report and contributory causes analysis. Anaesthesia 2013; 68: 1179–87. doi:10.1111/anae.12554
90
Hypoglycaemia associated with the use of incorrect arterial flush solutions I read the report of accidental hypoglycaemia reported in Anaesthesia with a sense of inevitability [1]. The problems that led to the publication of the NPSA guidance on arterial lines [2] had clearly not gone away after the guidance had been published and were identified in a review of patient safety incidents during 2009 and 2010 [3]. Following that review, I had written to highlight the problem to senior colleagues in critical care and, in an unpublished review, described the factors that should be addressed to prevent ongoing episodes of hypoglycaemia associated with the use of incorrect arterial flush solutions [4]. In the 30 episodes of incorrect flush solution identified as being reported within the North West of England since 2009, 12 were substitutions of saline by glucosecontaining solutions. In the 14 cases where the origin of the flush solution was stated, five were from the critical care unit where the line was
used and 11 were from other locations including six from the operating theatres. The incorrect selection of fluid was noted around the constitution of the fluid in three cases, during admission to critical care in seven cases, because of abnormal blood glucose measurements in six cases and on routine checks in the other 14 cases. Where glucose-containing solutions were associated with hyperglycaemia, this was identified by nursing staff who felt that the values (between 12 and 60 mmol.l1) did not fit the clinical scenario; the values were all checked with peripheral samples. The guidance on arterial lines issued by the NPSA clearly states that saline should be used in the constitution of arterial lines [2], but this guidance was given on the misconception by staff at the NPSA that clinical staff deliberately selected non-saline solutions. The guidance was not intended to say that specifically heparin should be avoided, and further guidance on heparin specifically excluded arterial lines [5]. It is unfortunate that the main message that seems to have come across from the arterial line guidance was to change from heparin-saline to saline [6], making it more difficult to differentiate between bags of saline and glucose. In the excellent editorial [7] commenting on the case report [1], Prof. Smith points out that we need systems in place to identify lessons that we may otherwise forget. I would strongly suggest that all critical care networks review their patient safety incidents using processes that we have developed and
© 2013 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
instituted across the North West of England [8]. By such review we can monitor trends to see the effects of the guidance and identify where further guidance is required; we have missed one opportunity to use this tool and we should not miss others. A. N. Thomas Salford Royal NHS Foundation Trust Salford, UK Email: [email protected] No external funding and no competing interests declared. Previously
Anaesthesia 2014, 69, 78–91
posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com. 5.
References 1. Gupta KJ, Cook TM. Accidental hypoglycaemia caused by an arterial flush drug error: a case report and contributory causes analysis. Anaesthesia 2013; 68: 1179–87. 2. National Patient Safety Agency. Infusions and sampling from arterial lines. Rapid Response Report, 2008. http:// www.nrls.npsa.nhs.uk/resources/?entryid45=59891 (accessed 11/11/2013). 3. Thomas AN, Taylor RJ. A review of patient safety incidents in critical care; a review of reports to the UK National Patient Safety Agency. Anaesthesia 2012; 63: 726–33. 4. Thomas AN, Buckley H. Prevention of harm associated with incorrect selection
6.
7.
8.
of fluids used to maintain arterial line patency. http://www.gmccn.org.uk/ patient-safety-review (accessed 11/11/ 2013). National Patient Safety Agency. Risks with ontravenous heparin flush solutions. Rapid response Report, 2008. www.nrls.npsa.nhs.uk/resources/?entryid45=59892 (accessed 11/11/2013). Leslie RA, Gouldson S, Habib N, et al. Management of arterial lines and blood sampling in intensive care: a threat to patient safety. Anaesthesia 2013; 68: 1114–9. Smith A. Lest we forget: learning and remembering in clinical practice. Anaesthesia 2013; 68: 1099–103. Thomas AN. Instructions for reviewing patient safety incidents. http:// www.gmccn.org.uk/patient-safety-review (accessed 11/11/2013). doi:10.1111/anae.12555
Visit the Anaesthesia Correspondence website at http://www.anaesthesiacorrespondence.com and comment on any article or letter in this issue of the Journal.
© 2013 The Association of Anaesthetists of Great Britain and Ireland
91
Correspondence
Table 1 Effect of contamination on blood sample biochemistry. The volume of blood (X, above) is 0.96 ml and that of flush (Y, above) is 0.4 ml.
Glucose; mmol.l1 Sodium; mmol.l1 Chloride; mmol.l1 Potassium; mmol.l1 Hydrogen ion; nmol.l1 pH
A
B
F
Concentration or value in blood
Concentration or value in flush contaminant
Final concentration ((A 3 X) + (B 3 Y)) or value
5 145 100 5 40
280 154 154 0 3160
16 145 102 4.8 165
7.4
5.5
6.8
As we emphasised in our paper, sodium chloride 0.9% with glucose 5% appears to be a particularly dangerous fluid in these circumstances. It has the capacity to be readily mistaken for sodium chloride 0.9% and a high enough glucose concentration to lead to markedly elevated glucose levels with very low levels of sample contamination. Other blood biochemistry is highly unlikely to be dramatically altered. T. M. Cook K. J. Gupta Royal United Hospital Bath, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
Reference 1. Gupta KJ, Cook TM. Accidental hypoglycaemia caused by an arterial flush drug error: a case report and contributory causes analysis. Anaesthesia 2013; 68: 1179–87. doi:10.1111/anae.12554
90
Hypoglycaemia associated with the use of incorrect arterial flush solutions I read the report of accidental hypoglycaemia reported in Anaesthesia with a sense of inevitability [1]. The problems that led to the publication of the NPSA guidance on arterial lines [2] had clearly not gone away after the guidance had been published and were identified in a review of patient safety incidents during 2009 and 2010 [3]. Following that review, I had written to highlight the problem to senior colleagues in critical care and, in an unpublished review, described the factors that should be addressed to prevent ongoing episodes of hypoglycaemia associated with the use of incorrect arterial flush solutions [4]. In the 30 episodes of incorrect flush solution identified as being reported within the North West of England since 2009, 12 were substitutions of saline by glucosecontaining solutions. In the 14 cases where the origin of the flush solution was stated, five were from the critical care unit where the line was
used and 11 were from other locations including six from the operating theatres. The incorrect selection of fluid was noted around the constitution of the fluid in three cases, during admission to critical care in seven cases, because of abnormal blood glucose measurements in six cases and on routine checks in the other 14 cases. Where glucose-containing solutions were associated with hyperglycaemia, this was identified by nursing staff who felt that the values (between 12 and 60 mmol.l1) did not fit the clinical scenario; the values were all checked with peripheral samples. The guidance on arterial lines issued by the NPSA clearly states that saline should be used in the constitution of arterial lines [2], but this guidance was given on the misconception by staff at the NPSA that clinical staff deliberately selected non-saline solutions. The guidance was not intended to say that specifically heparin should be avoided, and further guidance on heparin specifically excluded arterial lines [5]. It is unfortunate that the main message that seems to have come across from the arterial line guidance was to change from heparin-saline to saline [6], making it more difficult to differentiate between bags of saline and glucose. In the excellent editorial [7] commenting on the case report [1], Prof. Smith points out that we need systems in place to identify lessons that we may otherwise forget. I would strongly suggest that all critical care networks review their patient safety incidents using processes that we have developed and
© 2013 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
instituted across the North West of England [8]. By such review we can monitor trends to see the effects of the guidance and identify where further guidance is required; we have missed one opportunity to use this tool and we should not miss others. A. N. Thomas Salford Royal NHS Foundation Trust Salford, UK Email: [email protected] No external funding and no competing interests declared. Previously
Anaesthesia 2014, 69, 78–91
posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com. 5.
References 1. Gupta KJ, Cook TM. Accidental hypoglycaemia caused by an arterial flush drug error: a case report and contributory causes analysis. Anaesthesia 2013; 68: 1179–87. 2. National Patient Safety Agency. Infusions and sampling from arterial lines. Rapid Response Report, 2008. http:// www.nrls.npsa.nhs.uk/resources/?entryid45=59891 (accessed 11/11/2013). 3. Thomas AN, Taylor RJ. A review of patient safety incidents in critical care; a review of reports to the UK National Patient Safety Agency. Anaesthesia 2012; 63: 726–33. 4. Thomas AN, Buckley H. Prevention of harm associated with incorrect selection
6.
7.
8.
of fluids used to maintain arterial line patency. http://www.gmccn.org.uk/ patient-safety-review (accessed 11/11/ 2013). National Patient Safety Agency. Risks with ontravenous heparin flush solutions. Rapid response Report, 2008. www.nrls.npsa.nhs.uk/resources/?entryid45=59892 (accessed 11/11/2013). Leslie RA, Gouldson S, Habib N, et al. Management of arterial lines and blood sampling in intensive care: a threat to patient safety. Anaesthesia 2013; 68: 1114–9. Smith A. Lest we forget: learning and remembering in clinical practice. Anaesthesia 2013; 68: 1099–103. Thomas AN. Instructions for reviewing patient safety incidents. http:// www.gmccn.org.uk/patient-safety-review (accessed 11/11/2013). doi:10.1111/anae.12555
Visit the Anaesthesia Correspondence website at http://www.anaesthesiacorrespondence.com and comment on any article or letter in this issue of the Journal.
© 2013 The Association of Anaesthetists of Great Britain and Ireland
91
