Objectives and hypotheses
Are the objectives of the study clearly stated?
Is the study design suitable for the objectives
Who / what was studied?
Adult patients undergoing imaging studies that require nonionic radiographic contrast. Stable creatinine levels of 1.1 or less was required to participate in the study.
Was this the right sample to answer the objectives?
Is the study large enough to achieve its objectives? Have sample size estimates been performed?
Yes; the study was stopped prematurely when a statistical difference was found between the two groups.
Were all subjects accounted for?
Yes; 9 patients were excluded from each group.
Were all appropriate outcomes considered?
Has ethical approval been obtained if appropriate?
Were the patients randomised between treatments?
How was randomisation carried out?
Randomisation was performed by a computer generated schedule.
Are the outcomes clinically relevant?
Yes; contrast-induced nephropathy and subsequent longer hospitalisation times are clinically relevant outcomes.
Measurement and observation
Is it clear what was measured, how it was measured and what the outcomes were?
Yes; serum creatinine levels
Are the measurements valid?
Yes; serum creatinine was measured using an autoanalyzer by laboratory personnel
Are the measurements reliable?
Are the measurements reproducible?
Yes, however serum creatinie levels were measured only once per sample.
Were the patients and the investigators blinded?
Yes. Patients were not told to which group they were randomised. The investigators had limited contact with patients (for obtaining informed consent). Laboratory technicians performing serum creatinine levels were not told which group to which the patients belonged.
Presentation of results
Are the basic data adequately described?
Were groups comparable at baseline?
Yes. The mean baseline serum creatinine was slightly but not statistically higher in the group receiving sodium bicarb than those receiving normal saline.
Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
Are the results internally consistent, i.e. do the numbers add up properly?
Were side effects reported?
Yes, they included increaed blood pressure (with I.V. infusion), and an insignificant decrease in serum potassium.
Are the data suitable for analysis?
Are the methods appropriate to the data?
Are any statistics correctly performed and interpreted?
Are the results discussed in relation to existing knowledge on the subject and study objectives?
Yes; the results support the hypothesis that contrast-induced injury to the kidney is due to free radical activity.
Is the discussion biased?
Are the authors' conclusions justified by the data?
What level of evidence has this paper presented? (using CEBM levels)
Does this paper help me answer my problem?
Yes; it describes a pre-treatment option other than normal saline that is inexpensive, readily available and can prevent morbidity in patients receiving nonionic intravenous radiographic contrast.
Can any necessary change be implemented in practice?
Yes. For patients with a pretest creatinine of 1.1 or greater, a pharmacy protocol to mix 154 mEq/L NaHCO3 in D5W could be implemented and bolused at 3 mL/kg for one hour prior to contrast administration and continued at a rate of 1 mL/kg for 6 hours thereafter.
What aids to implementation exist?
Preparation of the above sodium bicarbonate solution would NOT be labor intensive, dificult to obtain or expensive. Dosing is simple and relatively quick. Components of the I.V. solution are non-allergenic.
What barriers to implementation exist?
1. Educating physicians and nursing staff
2. Protocol implementation in the Emergency Department and Pharmacy
3. Time for infusion prior to an urgently needed test (i.e. one hour might be too long to wait in some circumstances)