When filling out the form for a CT scan in you hospital you will not only have to provide clinical information about the patient but almost certainly also the latest creatinine levels. This information is required as many clinicians are worried that IV contrast media might cause iatrogenic acute kidney injury and therefore increased rates of dialysis, renal failure, and death. Despite several reports of contrast-induced nephropathies in the past, the causal relationship between IV contrast media and the development of acute kidney injury has been challenged recently (Read our previous summary HERE).
The major problem is that performing a randomized controlled trial to elucidate the true incidence of contrast-induced nephropathy is considered unethical because of the presumption that contrast media administration is a direct cause of acute kidney injury.
While the discussion goes on Hinson et al. have come up with another nice piece of evidence that in emergency situations there is no reason to withhold the application of IV contrast for CT scans when required.
In this single-center retrospective cohort study researchers have included a total of 17'934 patient visits to their emergency department over a period of 5 years. They analysed three patient groups that where demographically similar: contrast-enhanced CT, unenhanced CT and no CT scan performed. Patients were included when their initial serum creatinine level was between 35 umol/L and 352 umol/L. Of all CT scans, 57.2 percent were contrast-enhanced. The probability of developing acute kidney injury was 6.8 percent for patients undergoing contrast-enhanced CT, 8.9 percent for patients receiving unenhanced CT and 8.1 percent for patients not receiving CT at all. This proofs to be the largest controlled study of its kind in the emergency department and shows that:
In current clinical context, contrast media administration for CT scans is NOT associated with an increased incidence of acute kidney injury. And even though a large randomised controlled trial is still missing it seems safe...
There is no reason to withhold the use of IV contrast media in cases where contrast-enhanced CT is indicated to avoid delayed or missed diagnosis of critical disease.
Hinson J et al. Annals of Emergency Medicine, 2017; DOI: 10.1016/j.annemergmed.2016.11.021 OPEN ACCESS
Crit Cloud Review from 18/01/2015
When performing a kidney transplantation nowadays up to 50% of recipients developed a delayed graft function which is defined as the need of dialysis within seven days. The authors of this recently published NEJM-article asked themselves whether mild hypothermia might influence outcome in this regard.
In order to answer this question the investigators assigned organ donors after declaration of death according to neurologic criteria into two groups. They were either treated with mild hypothermia (34 to 35°C) or with normothermia (36.5 to 37.5°C). The target temperature was maintained until the patients were transferred to theatre for transplantation.
Primary outcome of this trial was delayed graft function among recipients. Secondary outcomes included the rates of individual organs transplanted into each treatment group at the total number of organs transplanted from each donor.
This trial had to be stopped early as an interim analysis showed significant efficacy of mild hypothermia. Up to this point a total of 572 patients received a kidney transplant (285 in the hypothermia group and 287 in the normothermia group). 28% of recipients in the hypothemia group developed delayed graft function compared to 39% in the normothermia group.
The authors therefore conclude that mild hypothermia significantly reduces the rate of delayed graft functions among recipients.
Anyhow, it seems reasonable not to get rid of your cooling devices!
Read more about the controversies of hypothermia in the ICU:
The Targeted Temperature Management Trial: Nielsen N, et al. New Engl J Med. 2013 Dec;369(23):2197-206
The 2 trials that introduced therapeutic hypothermia into ICU practice:
The Hypothermia After Cardiac Arrest Study Group, Holzer at al. New Engl J Med. 2002 Feb;346(8):549-556
Bernard S.A. et al. New Engl J Med. 2002 Feb;346(8):557-563
Review article on therapeutic hypothermia for non-VF/VT cardiac arrest:
Sandroni S. et al. Crit Care Med; 2013;17:215
Pyrexia and neurological outcome:
Leary M. et al. Resuscitation. 2013 Aug;84(8):1056-61
BIJC post on: The Effect of Pre-Hospital Cooling: Rather Worrying Results
In a letter to the editor of Intensive Care Medicine Soubirou et al. present the result of a study looking at the efficacy and safety of saline lock solution in maintaining short term hemodialysis catheters patency in ICU. This prospective cohort study looked at 100 double lumen hemodialysis catheters inserted in 75 patients managed with intermitted hemodialysis. At the end of each session the lumens were flushed with normal saline only. The investigators found no difference to 5 other studies using heparin or citrate.
Conclusion: Heparin is not necessary in this setting, citrate is an alternative, but saline seems just as good.
Soubirou JF et al. Intensive Care Med. 2014 June
One major concern when bringing a critically ill patient for a CT scan is the potential for acute kidney injury (AKI) by applying iodinated contrast media intravenously. Post-contrast AKI carries the risk of more permanent renal failure, dialysis and even death. The authors of this review article nicely summarize current evidence on this issue and show, that the risk of AKI secondary to contrast material (particularly when administered intravenously for contrast-enhanced CT) has been exaggerated in the past by older, noncontrolled studies.
In fact, by reviewing more recent evidence they come to the conclusion that the risk is almost nonexistent in patients with normal renal function. Even in patients with pre-existing renal insufficiency the risk of secondary contrast-induced AKI is probably much smaller than traditionally assumed.
Again they emphasize on the fact that volume expansion is the only preventive strategy with a convincing evidence base.
Nevertheless, the benefits of a contrast-enhanced exam still will have to be balanced with the remaining risk of AKI.
BioMed Research International. 2014, Article ID 859328
Dopamine has been widely used in the past for improving renal function but was abandoned due to lack of evidence and various potential serious side effects. In the new Heart Failure Guidelines 2013 of the AHA.pdf there is an interesting note in the section hospitalized patients with heart failure: low-dose dopamine infusion may be considered in addition to loop diuretic therapy to improve diuresis and better improve renal function. The level of evidence is IIb/B which means that efficacy is less well established and that there is greater conflicting evidence from trials. Indeed, when looking at the cited articles more questions than answer remain... but see yourself.
Giamouzis G, et al. .J Card Fail. 2010 Dec;16(12):922-30
Elkayam U, et al. Circulation. 2008 Jan 15;117(2):200-205