Sodium Bicarbonate for the prevention of contrast induced nephropathy in patients suspected with acute pulmonary embolism undergoing CTPA

Contrast induced nephropathy (CIN) can occur after injecting radiographic iso
osmolair contrast media. Patients with renal impairment or a decreased renal
function in combination with diabetis mellitus or Kalher's disease are at risk
for developing CIN.
A consensus of the CBO (Dutch Central guidance institute) advises to give
patients at risk a pre- and posthydration treatment each during 12 hours with
0,9% saline 1 ml/hr/kg bodyweight. In case of emergencies (non elective
examinations) a short pre-hydration during one hour with sodium bicarbonaat
1.4% 3 ml/hr/kg bodyweight is indicated, followed by a posthydration of 6 hours
1.4% sodium bicarbonate 1.5 ml/hr/kg bodyweight. This hydration regime is
studied in patient populations undergoing coronairy angiography. There is no
consensus on the exact implementation of hydration regimes with sodium
bicarbonate.

It is important to underline the vital indication of CTPA.

The risk of CIN is not only dependent of the risk profile of the patient but
also of the nature of examination, the amount of injected contrast media, the
distinction between, low, iso, en high osmolair contrast media and wheter
contrast media is injected intravenous or in the arterial circulation.

CIN has a low incidence following CTPA because of the low amounts of contrast
media, which is injected intravenous in a iso-osmolair concentration.
Furthermore, very few patients who develop CIN are not able to restore kidney
function after two months.

It is important to find out wheter prehydration prior to CTPA with a low
contrast load has a preventive effect on CIN because of the direct implication
it has on the safety and the amount of stress on the patient.

- Evaluation of mean increase in serum creatinine and the incidence of CIN
following CT-PA without prehydration compaired to a short prehydration regime
with sodium bicarbonate during one hour.
- Furthermore, the risk of developing CIN after CT-PA with iso osmolair
contrast media is studied for both patient groups.

Patients with an indication for hydration, are asked to participate in this
study. Patients a randomly asigned to one of the study arms.

- Group 1: sodium bicarbonate 1,4% (3ml/kg bodyweight) 1 hour prior to
administration of contrast media.
- Group 2: CT-PA without any hydration

Markers for kidney function and kidney damage are measured prior, 2 hours, 2-4
days and 2 months after CTPA. These measurement are used to determine the mean
increase in serum creatinie, the incidence of CIN and the confidence interval
of the incidence of CIN and the risk for developing CIN in both groups.

* group 1: sodium bicarbonaat 1,4% (3 ml/kg bodyweight) 1 hour prior to
administration of contrast media.
* group 2: CT-PA without any hydration.

The amount of stress on the patient for this study is very limited. Renal
function is rountinely measured prior to CT-PA. In this study, patients will
receive one extra venapuncture prior and two hours after CT-PA and are asked
for one portion of urine prior and after CT-PA.
The CBO advises to check renal function 2-4 days after CT-PA of all patients at
risk for CIN. In this study we will ask for one extra venapuncture and one
urine portion after 2 to 4 days.
If the renal function is decreased after 2 to 4 days according to the
defenition of CIN, patients are asked to come back after 2 months for some
extra bloodwork to determine whether there kidney function is restored or not.
This is not clinical practice.
Participation in this study results in one extra hospital visit if CIN is
established after 2 to 4 days. Patients probably will have advantage of this
accurate monitoring of kidney function.