Anesthetic Management of CKD and Uroabdomen

Question 1

Discuss what to monitor and how to maintain renal perfusion during anesthesia

Answer 1

1. maintain normal blood pressure
   -minimum MAP to maintain renal perfusion is 60mmHg
   -if really worried or longer procedure, place an arterial catheter for more accurate measurement

-maintain via:
–careful use of hypotension producing drug (injectables, inhalants)
–appropriate fluids: crystalloids, colloids
–+/- inotropes and vasopressors

2. provide adequate hydration
   -pre-anesthetic IV fluids if needed
   -intra-operative IV fluids
3. monitor urine output: 1-2ml/kg/hr

1st step to treating anesthetic hypotension is to decrease any inhalant currently being used!

Question 2

what are anesthetic concerns associated with chronic kidney disease?

Answer 2

1. anemia
2. hyperkalemia
3. uremia/azotemia
4. metabolic acidosis
5. nausea/vomiting
6. hypertension
7. volume sensitivity

Question 3

Choose anesthetic protocols for patients with urinary tract disease

Answer 3

1. pre-anesthetic eval:
   -thorough history and physical exam, min database, pre-anesthetic BP
2. drug choices: almost all eliminated by kidney as inactive form
   -tiletamine (telazol) is eliminated in active form in urine!
   -ketamine in CATS is excreted in its active form through urine (excreted inactive in other species); so high doses of ketamine = prolonged recovery time in cats
3. anesthetic maintenance:
   -monitor BP: actively! don’t wait until below 60 to act!
   -monitor volume carefully: anemia, volume sensitivity
   -ventilate? don’t want to add respiratory acidosis to any other acidosis, but ventilation decreases cardiac output (lacking inspiratory phase to help with preload); maybe consider manual more delicate breaths instead of mechanical ventilation if need help breathing
4. recovery:
   -monitor urine output: place U cath
   -monitor potassium: can decrease in patients that were obstructed, supplement when indicated
   -monitor pain: provide analgesia

Question 4

Identify anesthetic risks and complications of patients with uroperitoneum

Answer 4

1. metabolic acidosis:
   -reduced cardiac contractility
   -higher plasma concentration of active form of many drugs
2. hyperkalemia and arrhythmias
3. uremia/azotemia
4. dehydration and shock

Question 5

Describe treatment principles for hyperkalemia

Answer 5

1. plasma volume expansion:
   -hypertonic saline to increase intravascular volume and increase plasma Na+
   -is okay to use fluids containing low amounts K+ as long as expanding volume
   -Na+ may counteract the effects of hyperkalemia on arrhythmias
   -careful if patient is obstructed!
2. transfer potassium into cells
   -dextrose infusion to increase insulin release
3. sodium bicarbonate: controversial, last step, if pH really low
   -would reach for sooner under general anesthesia bc we can ventilate for them to breathe extra off
4. calcium gluconate, calcium chloride, or calcium borogluconate
5. beta-2 agonists: stimulate insulin release: albuterol, terbutaline, dobutamine? (mostly beta 1 so dobutamine given to help with CO and contractility and might help some with potassium, but not primarily for potassium)
   -do same as dextrose
6. during anesthesia:
   -avoid agents with dysrhythmogenic potential (alpha 2 agonists)
   -pre-oxygenate and supplement oxygen throughout induction
   -control ventilation
   -continued K+ monitoring
   -treat arrhythmias as they arise

Question 6

describe anesthesia and the kidney

Answer 6

anesthetic drugs are not harmless to the kidneys! almost all of them lower renal blood flow via systemic hypotension and renal vasoconstriction

Question 7

why do we want MAP to be NO LESS than 60mmHg during anesthesia?

Answer 7

that’s what the kidney needs!!

between 60-160 is happy zone

for all species, this is what the kidney needs (even though try to maintain large animals higher is bc their muscle mass not their kidneys)

Question 8

describe how premed drugs affect the body/kidney

Answer 8

1. acepromazine: peripheral vasodilation, block dopaminergic receptors
2. opioids: bradycardia
3. alpha 2 agonists: increase urine output, decrease cardiac output (vasoconstriction, hypertension)
4. NSAIDs: decouple renal autoregulation of blood flow

Question 9

describe how injectable induction drugs affect the body/kidney

Answer 9

1. propofol: vasodilation leading to hypotension (brief)
2. etomidate: minimal cardiovascular effects but adrenocortical suppression
   -good drug to use to maintain cardiac output
3. ketamine: catecholamine release leading to increased cardiac output and direct myocardial suppression

Question 10

describe how inhalant anesthetics affect the body/kidney

Answer 10

all can cause peripheral vasodilation leading to systemic hypotension!

sevoflurane can form compound A (toxic to kidneys; only an issue if very low flow on oxygen machine; 10-20ml/kg/min usually safe)

Question 11

describe the receptors that inotropes and vasopressors act on

Answer 11

receptors:
1. D1/D2: dopaminergic, some in kidneys
2. alpha: DP reg, smooth muscle constriction, blood flow
3. beta 1: in heart and kidneys; HR, contractility, BP and blood volume
4. beta 2: relax smooth muscles
5. V1 in vessels, cause vasoconstriction
6. V2 in kidneys stimulate collecting ducts to retain more water (increase BP)

dopamine: D1/D2, alpha, beta 1

dobutamine: beta 1 and 2

norepinephrine: alpha and beta 1

vasopressin: V1/V2