Renal Flashcards
What urine to plasma osmolarity ratio indicate prerenal oliguria?
Greater than 1.5
Normal urine osmolarity is 294 so 294 X 1.5 = 454
What does urine to plasma osmolality ratio indicate?
The kidney’s ability to concentrate urine
Which part of the nephron is responsible for the most sodium reabsorption?
Proximal tubule
What part of the nephron accounts for most bicarbonate reabsorption?
The proximal tubule because hydrogen ions are secreted when sodium is reabsorbed
What can mannitol cause in a TURBT?
Acute intra vascular expansion and pulmonary edema causing tachycardia, tachypnea, bradycardia
How long does it take for angiotensin II to be circulating after hypotension?
20 minutes
What does renin do?
Cleaves angiotensin to angiotensin I
What does ACE do?
Cleaves angiotensin I to angiotensin II
What does angiotensin II do?
Causes direct vasoconstriction in arterioles
Causes efferent vasoconstriction
Stimulates aldosterone from the zona glomerulosa
Why do patients on ACEi and ARBs have refractory hypotension?
Because the RAS system has been chronically inhibited so there is no angiotensin response or vasoconstrictor response to norepinephrine
What are the independent risk factors for postoperative renal failure in noncardiac cases in people with normal pre operative renal function?
Age greater than 59 Chronic liver disease BMI > 32 COPD PVD emergency surgery High risk surgery
What are the risk factors in patients with CKD for postoperative ARF?
Age greater than 56 Male Creatinine > 1.2 Diabetes on insulin Active CHF Ascites Emergency, intra peritoneal surgery
What is the the most accurate measure of predicting acute renal failure?
Creatinine clearance
What is the equation for creatinine clearance?
Urine Cr X urine volume/plasma creatinine
Why does a FeNa greater than 4 % indicate?
Postrenal
