Acute Kidney Injury (AKI): General Approach

00:01 What would be a good general approach to a patient who has AKI? We've talked about kind of different approaches that are specific to each of our patients but it's important to keep some general points in mind when you're approaching a patient who's sitting in front of you.

00:14 Number one, look for episodes of prolonged hypotension, Was this patient perhaps on ICU? Did they have septic shock? Number two - has that patient have medications or nephrotoxic exposures that can really induce a kidney injury? Remember we talked about radiocontrast exposure from CT scans or angiograms in a vulnerable population Were they on medications like NSAIDS? Remember how much nephrologists really are not the friend of NSAIDS because of the fact in this case, they can impair autoregulation, they can also cause things like allergic interstitial nephritis.

00:50 We talked about how aminoglycosides and amphotericin can actually cause tubular toxicity and medications like acyclovir can cause crystal precipitation.

01:01 And remember again as I mentioned, medications can cause allergic interstitial nephritis like penicillin.

01:08 You want to do a good physical exam so it's important to estimate volume status.

01:13 Let's look at the next things and estimate patient's jugular venous pressure.

01:17 We can look at their skin turgor to tell us a little bit more about their volume status.

01:21 It'd be important to look for things like rashes.

01:24 In our patient who has AIN, they might present with that exanthematous drug rash, or livedo reticularis in the case of cholesterol embolization or renal atheroembolic disease.

01:35 Imaging is gonna be critical in this population.

01:37 An ultrasound is relatively cheap and quick to get and that can rule out obstruction in a large portions of patients who are going to present with postrenal syndrome.

01:48 And of course, always look at the urine.

01:51 The urine holds clues for just about everything .

01:55 So remember the importance of FENa that we talked about to distinguish between prerenal disease and ATN.

02:01 Proteinuria and hematuria, if we see that on a urine analysis, that's really gonna point us to the direction of glomerular diseases and crystals can be seen with intertubular crystal obstruction or nephrolithiasis or stone disease.

02:18 Sediment review is also critical and that's probably my favorite part of the workup so this is where I'm looking at the urine directly under microscopy.

02:27 So if I see this beautiful picture over here to the right which is muddy brown cast in a patient who has ATN from radiocontrast exposure then I'm really really thinking about ATN so I really want you to think about that because that is going to show up not only in your clinical practice but you're gonna see that in your board exams as well.

02:43 So muddy brown cast really are specific for ATN White blood cell cast can be suggestive of allergic interstitial nephritis.

02:55 And finally dysmorphic red blood cells - those are those funny-shaped red blood cells seen in the urine sediment or red blood cell cast as well as a couple of white blood cell cast can be very suggestive of rapidly progressive glomerulonephritis.

03:10 And of course, we want to do renal biopsies in our selected cases.

03:17 So just some general principles for you to think about when it comes to the treatment of your patient who has acute kidney injury It's always important regardless of the etiology to ensure that renal artery perfusion is maintained.

03:30 We want that mean arterial pressure to be somewhere between 65 to 70 mmHg.

03:37 We want to avoid further nephrotoxic exposures including NSAIDS or nephrotoxic medications.

03:43 If I know that my patient already has AKI, I absolutely need to make sure that nobody is gonna be giving them something like ibuprofen or a medication that can cause tubular toxicity.

03:56 And I need to ensure that any renally cleared medications are appropriately dosed for the patient's renal function or GFR.

04:04 That's critical because remember, those medications can build up to toxic levels if we are not dosing them correctly for our patient's renal function.

04:13 And finally, in coming to treatment of our patients with AKI, there's renal replacement therapy with acute hemodialysis.

04:22 And this is really indicated in patients who have complications of acute kidney injury This would include somebody who has refractory acidemia meaning that they have a metabolic acidosis that I can't treat medically, or somebody that's so volume overloaded they're at risk of pulmonary edema or if they're already ventilated.

04:40 They might be having increasing FiO2 requirements because they have so much volume.

04:46 Patients who are hyperkalemic that again is refractory to medical treatment and finally patients who develop uremic syndrome particularly patients who have pericarditis.

04:58 That is an emergency for dialysis.

05:01 A couple of caveats that I'd like to mention about renal replacement therapy with acute hemodialysis: There’s no benefit to starting renal replacement therapy early or before complications arise.

05:13 But it doesn't mean that we as nephrologist can't individually tailor therapy for our specific populations.

05:19 I also want you to keep in mind that renal replacement therapy doesn't hasten renal recovery but it's certainly is gratifying to be able to provide a therapy as a nephrologist that saves patient's lives.

05:33 And with that, this concludes our AKI portion.