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Emerg Med J. 2007 October; 24(10): 722–723.
PMCID: PMC2658443

Capillary blood gases as an alternative to arterial puncture in diabetic ketoacidosis

Capillary blood gases as an alternative to arterial puncture in diabetic ketoacidosis

Report by Simon F J Clarke, Consultant in Emergency Medicine

Checked by Andrew Parfitt, Consultant in Emergency Medicine

Frimley Park Hospital, Frimley, UK


A short cut review was carried out to establish whether capillary blood rather than arterial blood can be used to assess acid base status in patients with diabetic ketoacidosis. A total of 25 papers were found using the reported searches, of which one presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of this best paper are presented in table 11.. It is concluded that while the correlations in the small study found were good, there is insufficient evidence to recommend adoption of this practice in the emergency setting.

Table thumbnail
Table 1

Three‐part question

In [patients with diabetic ketoacidosis] can [capillary blood be used as an alternative to arterial puncture] for [guiding appropriate therapy]?

Clinical scenario

A patient attends the emergency department with diabetic ketoacidosis. There have been previous similar attendances and there is a reluctance to have arterial blood gases taken; you wonder if capillary blood can be used as an alternative to arterial puncture.

Search strategy

Medline using the OVID interface 1950 to July week 4 2007: [exp capillaries/OR] AND [exp blood gas analysis/OR blood] AND [exp diabetes mellitus/OR].

Embase using the Dialog Datastar interface 1974–07/2007: [capillary ADJ blood ADJ gas] AND [diabetes ADJ mellitus].

The Cochrane Library Issue 3 2007: Cochrane Reviews (capillary):ti,ab,kw AND MeSH descriptor Diabetes Mellitus explode all trees 0 records

Search outcome

Twenty‐five papers were found by the Medline search, of which one was relevant to the question (table 11).). Sixty‐one papers were identified by the Embase search, but none of these were relevant to the question.


The paper suggests that capillary blood might be a useful alternative to arterial puncture for early assessment of acid‐base balance in diabetic ketoacidosis. However, it was a small study, samples were drawn 2 h after initiation of treatment, and not enough clinical details were given to assess the influence of confounding factors—in particular, the patients' blood pressures were not described. There are theoretical concerns that hypotension might lead to hypoperfusion of the capillary beds and this would lead to capillary blood becoming more like venous and less like arterial blood.

Clinical bottom line

There is insufficient evidence to recommend the use of capillary blood in the assessment of acid–base status in patients with diabetic ketoacidosis in the emergency setting; more research is needed to answer this question.


  • Hale P J, Nattrass M. . A comparison of arterial and non-arterialized capillary blood gases in diabetic ketoacidosis. Diabet Med 1988;5:76-8. [PubMed]

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