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Three Part Question

In [a child with DKA]can a [venous blood sample] demonstrate accurately the degree of [acidosis]?

Clinical Scenario

A known diabetic child presented to ED with abdo. pain vomiting and high blood glucose, you suspected DKA,you canulated the child and took blood samples including a sample for venous gases but your FY2 wondered (without chalenging your autharity) whether a venous sample is good enough to reflect the degree of acidodsis as compared to an arterial sample? you thought the answer was yes but wasn't sure about the evidence.

Search Strategy

Ovid MEDLINE(R) 1950 to May Week 3 2009.

[diabetic ketoacidosis.mp. or exp diabetic ketoacidosis/ OR exp Diabetes Mellitus, type 1/ OR exp hyperglycaemia AND Blood Gas Analysis] LIMIT to [English language and ''all child (0-18 yrears)''

Search Outcome

22 papers were found of which 4 were relevant

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Yuksel Gokel; Saime Paydas; Zikret Koseoglu; Nazan Alparslan; Gulsah Seydaoglu Jul/Aug 2000 Turkey	Venous and arterial blood samples from chronic Uraemic patients(n=100),DKA patient(n=21) and healthy controls(31).	a comparison study of 152 venous and arterial blood samples from chronic Uraemic patients,DKA patient and healthy controls which were analyzed for measurememnt of blood gas and acid-base status.	to examine a plausible correlation between venous and arterial blood gas values in acidotic patients with chronic uremia or diabetic ketoacidosis (DKA).	The means of arterial and venous pH, and arterial and venous HCO(-)(3) values for the uremic patients were 7. 17 +/- 0.14, 7.13 +/- 0.14, 10.13 +/- 4.26 and 11.86 +/- 4.23 mmol/l, respectively. The respective mean differences between arterial and venous pH values and arterial and venous HCO(-)(3) values were 0.04 +/- 0.02 and -1.72 +/- 0.42 mmol/l, respectively, for these patients. The means of the laboratory findings of DKA patients were arterial pH, 7.15 +/- 0.15; venous pH, 7.10 +/- 0.15; arterial HCO(-)(3), 8. 57 +/- 5.71 mmol/l and venous HCO(-)(3), 10.46 +/- 5.73 mmol/l. The respective mean differences between arterial and venous pH and arterial and venous HCO(-)(3) for this group were calculated to be 0. 05 +/- 0.01 and -1.88 +/- 0.41 mmol/l. In the healthy controls, the means of arterial and venous pH, and arterial and venous HCO(-)(3) values were 7.39 +/- 0.02, 7.34 +/- 0.02, 24.91 +/- 0.82 and 26.57 +/- 0.83 mmol/l, respectively. For the healthy controls the mean differences between the respective values in arterial and venous pH, and arterial and venous HCO(-)(3) were 0.05 +/- 0.01 and -1.66 +/- 0. 58 mmol/l. Although in healthy controls the correlation between arterial and venous pH values (r(2): 0.595) and arterial and venous HCO(-)(3) values (r(2): 0.552) were moderate, these correlations were significantly increased in both the acidotic patient group (r(2): 0.979 and 0.990) and the DKA group (r(2): 0.989 and 0.995) CONCLUSION: A venous blood sample can be used to evaluate the acid-base status in uremic and DKA patients.	small study, DKA patients were only 21 results were different in the control group compared to uraemic and DKA group
O John Ma; Micheal D Rush; Michelle M Godfrey; Gary Gaddis Aug 2003 USA	patients with suspected diabetic ketoacidosis (DKA) with capillary blood glucose equal to or greater than 200 mg/dL, ketonuria, and clinical signs and symptoms of DKA.	Prospective observational study to test the hypothesis that arterial blood gas (ABG) results for patients with suspected diabetic ketoacidosis (DKA) do not influence emergency physicians' management decisions and to assess correlation and precision between venous pH and arterial pH.	gas (ABG) results for patients with suspected diabetic ketoacidosis (DKA) do not influence emergency physicians' management decisions	ABG analysis changed the emergency physicians' diagnosis in 2/200 cases (1.0%; 95% confidence interval [95% CI] = 0.3% to 3.6%), altered treatment in 7/200 cases (3.5%; 95% CI = 1.7% to 7.1%), and changed disposition in 2/200 cases (1.0%; 95% CI = 0.3% to 3.6%). The pH value of the ABGs changed the treatment or disposition in 5/200 patients (2.5%; 95% CI = 1.1% to 5.7%). The Po^sub 2^ and Pco^sub 2^ results of the ABGs altered treatment and disposition in 2/200 patients (1.0%; 95% CI = 0.3% to 3.6%).	small study, 48 out of 200 were DKA
			to assess correlation and precision between venous pH and arterial pH	Venous pH correlated well with arterial pH (r = 0.951), and bias plotting yielded a bias value of -0.015 (+ or - 0.006 pH units).
Nemat Bilan, Afshin G. Behbahan, A. J. Khosroshahi May 2008 Iran	Children with 10 most common diseases in pediatric intensive care unit (PICU)including respiratory distress syndrome, neonatal sepsis, renal failure, pneumonia, diabetic ketoacidosis, status epilepticus,neonatal seizure, shock, congestive heart failure and congenital heart disease	In a cross-sectional analytical study from September 2004 to September 2005, 200 patients in 10 disease categories received blood gas analysis. Results of blood-gas tests such as pH, PCO2 and HCO3 of both arterial and venous blood samples (simultaneously taken from each patient) were recorded and compared by statistical analysis (kappa statistics) to determine their validity and clinical agreement.	evaluate the validity of VBG and its clinical agreement with ABG in the 10 most common diseases in pediatric intensive care unit (PICU), and to answer how far it can replace the ABG test.	respiratory distress syndrome, neonatal sepsis, renal failure, pneumonia, diabetic ketoacidosis and status epilepticus, VBG analysis showed a good validity (high sensitivity and specificity) accompanied by a suitable clinical agreement (over 40%), but in other diseases such as neonatal seizure, shock, congestive heart failure and congenital heart disease, there was either an inappropriately low validity or a weak clinical agreement (under 20%).	population different (PICU) studying other conditions in addition to DKA

Comment(s)

Obtaining an ABG sample is painfull, technically difficult and can result in complications including:bleeding, aneurysm formation, thrombosis of the artery infection and loss of function of the extremity. Researchers have been looking for alternatives for arterial sampling for yrears, and in DKA we are mainly looking for pH and HCO`3 values rather than PO2 level and venous sampling serves that purpose well.All the above studies have shoen that Venous Blood Gas is acurately reflective of the degree of acidosis in DKA.

Clinical Bottom Line

venous blood pH and bicarb. closely correlate with arterial values and hence VBG can subistute ABG in DKA

References

1. Brandenburg, Mark A. MD; Dire, Daniel J. MD Comparison of Arterial and Venous Blood Gas Values in the Initial Emergency Department Evaluation of Patients With Diabetic Ketoacidosis © Mosby-Year Book Inc, Annals of Emergency Medicine April 1998, pp 459-465
2. Yuksel Gokel; Saime Paydas; Zikret Koseoglu; Nazan Alparslan; Gulsah Seydaoglu Comparison of blood gas and acid-base measurements in arterial and venous blood samples in patients with uremic acidosis and diabetic ketoacidosis in the emergency room Americal Journal of Nephrology Jul/Aug 2000 pg. 319, 5pgs.
3. O John Ma; Micheal D Rush; Michelle M Godfrey; Gary Gaddis Arterial blood gas results rarely influence emergency physician management of patients with suspected diabetic ketoacidosis Academic Emergency Medicine August 2003, pg. 836
4. Nemat Bilan, Afshin G. Behbahan, A. J. Khosroshahi Validity of venous blood gas analysis for World Journal Of Pediatrics-China May 2008, 114-117