Acute renal injury: Diagnosis, management and prognosis

Presenter: David Walker, BVetMed(Hons) DipACVIM DipECVIM-CA MRCVS, Director Anderson Moores, RCVS and European Specialist in Small Animal Internal Medicine, American Specialist in Small Animal Internal Medicine

Imagine attending a CPD course where the majority of its content covers fluid therapy and, despite this, at no point does your mind start to wander about what you are going to have for dinner tonight. In fact it holds your interest through the entirety of the session. I would never have thought it possible had I not watched last week’s webinar led by David Walker, discussing acute kidney injury (AKI) in small animals.‏

Fluid therapy is the mainstay of treatment for AKI and by getting this right you offer your patient the best chance of survival. Get it wrong, and these animals could suffer from volume overload as a result of administering too much fluid (as unfortunately is so often the case) which effectively equates to being drowned. Hence David’s focus towards the importance of fluid therapy.

David advised on firstly addressing the dehydration deficit in these patients which must always be replaced before any meaningful measurements can be taken for urine output. Assessing the percentage of dehydration can be tricky as it is very subjective, with physical findings associated with dehydration also being affected by a number of other factors. For example, skin tenting may be more obvious in older patients that have lost a degree of dermal elasticity through age. David advises that if in doubt and having difficulty assessing the level of dehydration, it is always best to assume a minimum baseline of 5% dehydration for all AKI cases. The fluid deficit (in litres) for dehydration can then be measured as % dehydrated x body weight x 0.01 and should be replaced over a 4-6 hour period along with replacement maintenance fluids (sensible and insensible losses = 66ml/kg/day) and any ongoing losses such as fluid lost from vomiting and diarrhoea.

After replacing the dehydration deficit over 4-6 hours, urine output can be measured and replaced accurately along with insensible losses (22ml/kg/day) and any ongoing losses. David recommends monitoring urine output every 2 hours initially and then every four hours. If a patient is suffering from oliguria (< 0.5 mls/kg/hr) or anuria (<0.1mls/kg/hr), it is very important not to overload these patients with fluid, the excess of which will inevitably be dumped into their thorax or abdomen, or both. Urine output should, under normal conditions, be 1-2mls/kg/hr but if a patient is suffering from oliguria or anuria, diuretics such as furosemide, mannitol and dopamine are indicated and their use is discussed further by David within this webinar. If a patient remains anuric despite being treated with diuretics, then dialysis is indicated but he warns that owners could end up with bills of anywhere between £6000-£10000 by going down this route. This veterinary webinar offered a significant amount of practical information on how to manage cases of AKI. Fluid therapy is key to managing these patients, and several examples were cited explaining some of the complexities involved in calculating fluid replacement. Managing many other complications seen with AKI were also discussed, including hypertension (seen in 30-80% of cases), hyperkalaemia, anorexia and gastric ulceration. This webinar is essential viewing for any vet dealing with medical cases and, as AKI has an overall mortality rate of 60%, we need as much help as possible to ensure these patients are offered the best possible outcome. The Stethoscope (MRCVS) buy-now1