Anesthetic considerations for urologic surgery Flashcards
1
Q
How much cardiac output does the kidney receive?
A
20-25%
2
Q
The nephron is made up of
A
outer cortex & inner medulla
3
Q
Homeostasis is maintained in the kidney through
A
filtration
reabsorption &
tubular excretion
4
Q
Normal GFR is
A
125 mL/min
5
Q
Up to ____ of the filtrate is reabsorbed
A
99%
6
Q
Things that should not be seen in the urine include
A
glucose, protein, bilirubin
7
Q
The renal vasculature is innervated by
A
SNS
8
Q
Renal hormones include
A
aldosterone, antidiuretic hormone, angiotensin, atrial naturetic factor, vitamin D, prostaglandins
9
Q
Catecholamines result in a
A
decrease in urine output
10
Q
Anesthetic drugs affect the kidneys by
A
depress normal renal function
impairment of autoregulation
renal blood flow may decrease by 30-40%
11
Q
General anesthesia is associated with a decrease in
A
renal blood flow GFR urinary flow electrolyte secretion -similar changes occur after spinal & epidural anesthesia- magnitude of change parallels degree of sympathetic block & BP depression
12
Q
All ______ cause mild increase in renal vascular resistance
A
volatile anesthetics
-compensatory mechanism in response to decreases in CO & SVR
13
Q
Historically________ caused high fluoride ion concentrations & _________ characterized by polyuria
A
methoxyflurane; nephrotoxicity
14
Q
These factors attenuate reductions in renal blood flow & GFR
A
preoperative hydration, decreased concentrations of volatile anesthetics, & maintenance of blood pressure
15
Q
Sevoflurane has not
A
been associated with nephrotoxicity even though it has been associated with high fluoride levels
16
Q
Sevoflurane produces
A
Compound A which can potentially cause nephrotoxicity
17
Q
In an effort to decrease risk of compound A with sevoflurane,
A
use high gas flows (1L/min FGF for 2 MAC-hours max)
decrease gas concentration
use of carbon dioxide absorbents
18
Q
Isoflurane & desflurane are
A
not associated with nephrotoxicity
19
Q
Signs and symptoms of fluoride nephrotoxicity include
A
polyuria hypernatremia serum hyperosmolality elevated BUN & creatinine decreased creatinine clearance
20
Q
Nephrotoxicity with volatile anesthetics is related to
A
dosage, duration, & peak fluoride concentrations
21
Q
Fluoride ion toxicity
A
fluoride interferes with active transport of sodium & chloride in the loop of Henle
POTENT VASOCONSTRICTOR
potent inhibitor of many enzyme systems (ADH
22
Q
Nephrotoxicity results in
A
proximal tubular swelling & necrosis
23
Q
An acute kidney injury is defined as
A
a renal functional or structural abnormality that occurs within 48 hours- increase in creatinine 0.3 mg/dL or 50% increase; UO <0.5 mL/kg/hr x 6 hours
24
Q
Risk for acute kidney injury is increased by
A
hypovolemia, electrolyte imbalance, & contrast dye
25
Types of AKI include
prerenal, intrinsic, & post renal
26
Describe the cause of prerenal AKI
hypoperfusion of the kidneys without parenchymal damage
27
Describe the cause of intrinsic AKI
result of damage to renal tissue
28
Describe the cause of postrenal AKI
due to urinary tract obstruction
29
Provide examples of prerenal AKI
hemorrhage, vomiting, diarrhea, diuretics, sepsis, shock, CHF, norepinephrine, NSAIDs, ACE-I
30
Provide examples of intrinsic AKI
tubular injury due to hypoperfusion, myoglobin, chemotherapy, infections, lymphoma, toxemia of pregnancy, vasculitis
31
Provide examples of postrenal AKI
renal calculi, peritoneal mass, prostrate/bladder urethra tumor, fibrosis, hematoma, & strictures
32
Risk factors for AKI include
aging- >50 years of age, preoperative renal dysfunction
comorbidities- cardiac failure & hepatic failure
surgical procedures- cardiac bypass, aortic cross-clamp, arteriograpy, intra-aortic balloon pump
emergency or high risk procedures- ruptured AAA, ischemic time, large volume of blood transfusion
33
Describe how to mitigate risks of AKI
hydration, limit contrast dye, diuretics
34
Anuric is defined as
UO <100 mL/day
35
Polyuric is defined as
UO >2.5L/day
36
Oliguric is defined as
UO <400 mL/day
37
AKI preoperative treatment includes
fluid deficits- BALANCED SALT SOLUTION ( NS) to minimize ADH & RAAS release
attenuation of surgical stress
patient monitoring considerations- arterial line, transesophageal echocardiogram, CVP, foley catheter
38
Fluid replacement for perioperative AKI treatment includes
500-1L bolus for hourly UO below acceptable levels
colloids may not be superior to crystalloids
high risk patients 0.5-1.0 mL/kg/hr
39
AKI perioperative treatment includes
fluid replacement
improve cardiac output
normalize SVR
diuretic use to prevent oliguria is not recommended
40
Early treatment of prerenal causes has
best outcomes
41
Postrenal has good prognosis with
early identification
42
The most difficult AKI type to treat is
intrarenal
43
Most common cause of AKI is
prolonged hypoperfusion
44
_______ reduces mortality in AKI more than dialysis
prophylaxis
45
Duration & magnitude of initial insult determine
severity of AKI
46
Key strategy for perioperative management of AKI is to
limit magnitude & duration of renal ischemia
47
Treatment for AKI inclues
administering volume (NS) to euvolemia
improving CO by afterload reduction
normalizing SVR
48
Renal function decreases
10% per decade
49
CKD is present when
GFR is less than 60 mL/min/1.73 m2 for three months
50
Signs & abnormal labs do not appear until
less than 40% of normal functioning of nephrons remain
51
When 95% loss of renal function occurs, symptoms include
uremia, volume overload, CHF
52
The respiratory effects of CKD includes
respiratory depression secondary to delayed clearance
53
The neurologic effects of CKD include
fatigue & weakness are early complaints
autonomic neuropathy--> b/c electrolytes mess w/ nerve functioning--> causes airway & aspiration risk
disequilibrium syndrome- severe neurologic effects
54
The cardiovascular effects of CKD include
hypertension & CHF- 90%volume dependent; 10% secondary to increased renin; pericardial effusion
pericarditis seen in patients with severe anemia
ischemic heart disease is most common cause of death- outcomes better in CABG with angioplasty
55
Gastrointestinal effects of CKD include
dialysis patients are at greater risk for GI bleeding
56
Hematologic effects of CKD include
normochromic, normocytic anemia- decrease in erythropoietin production, reduction in erythrocyte life secondary to dialysis, blood loss from frequent sampling
prolonged bleeding- decrease in platelet function, dialysis within 24 hours will correct, desmopressin increases levels of Factor VIII
57
Infectious effects of CKD include
protein malnutrition
| neutrophil, monocyte, & macrophage changes
58
Endocrine effects of CKD include
hyperparathyroidism
| adrenal insufficiency
59
The leading cause of death in dialysis patients is
infection
60
Describe electrolyte effects of CKD
sodium wasting
hypocalcemia
hyperkalemia
61
Hyperkalemia is a
serious disturbance in patients with renal disease
| -fatal dysrhythmias or cardiac standstill can occur when K+ levels reach 7-8 mEq/L
62
Treatment of hyperkalemia includes
```
25-50 g dextrose
10-20 unites of insulin
50-100 mEq of sodium bicarb
calcium chloride
albuterol
```
63
Preoperative lab levels of potassium should be
checked even if dialysis is performed within 6-8 hours of surgery
64
Physiologic effects of dialysis include:
hypotension, muscle cramping, anemia, & nutritional depletion
65
EKG changes for the patient with hyperkalemia include
peaked T waves
progresses to widen QRS, peaked T waves
sinusoidal waves next- very bad
66
Preoperative anesthetic considerations for the CKD patient includes
pertinent lab & diagnostic tests
| continue antihypertensive medications
67
Intraoperative anesthetic considerations for the CKD patient includes
monitoring, regional anesthesia, general anesthesia, fluid management
68
Postoperative anesthetic considerations for the CKD patient includes
dialysis within 24 hours
69
In anuric patients, it is contraindicated to give
potassium containing solutions (LR)
70
Blood products are reserved for
patients who need increased oxygen-carrying capacity
71
Fluid management for the prevention of AKI includes
UO 0.5-1.0 mL/kg/hr recommended
| mildly compromised function- balanced salt solution at 3-5 mL/kg/hr. with 500 mL bolus as needed
72
Intraoperative monitoring is based on
patient's physiologic status & surgical procedure & includes ECG, pulse oximetry, arterial catheter, & echo
73
Pharmacologic considerations for the patient on dialysis include
morphine is not removed by dialysis
meperidine cannot be removed by dialysis
H2 blockers are highly dependent on renal excretion
hydromorphone has active metabolite that can accumulate
74
Describe fluid management for the dialysis patient
insensible losses- replace with 5-10 mL/kg of D5W
| if urine is produced- replace with 0.45% saline
75
Fluid management for the renal insufficiency/ESRD patient icnldues
replace volume deficit preoperatively
intraoperative losses greater than 15% should be replaced with colloid 1:1
crystalloid without potassium at 2-3 mL/kg/hr
76
The most reliable test for renal function is
creatinine clearance
77
Normal creatinine clearance is
95-150 mL/min.
78
Creatinine clearance measures
glomerular ability to excrete creatinine in urine
mild dysfunction 50-80 mL/min.
moderate dysfunction <25 mL/min
<10 mL/min requires dialysis
79
Blood urea nitrogen is
10-20 mg/dL
| BUN: creatinine ratio is 10:1
80
Serum creatinine normal is
0.7-1.5 mg/Dl
| for every 50% reduction in GFR, serum creatinine doubles
81
Regional anesthesia for patients with kidney disease is
generally well tolerated
82
Major concerns for regional anesthesia for the patient with kidney disease include
intolerance, coagulopathy, peripheral neuropathy, risk of infection
83
Block duration is _____ by renal failure
not affected
84
Spinal & epidural considerations for the patient with renal failure includes
platelet count, PT/PTT, ASRA coags
85
In general anesthesia for the renal failure patient, IV drugs are affected by
volume of distribution is increased
decreased protein binding
low pH
renal excretion
86
Describe the effects of renal failure on ketamine, benzodiazepines, propofol, dexmedetomidine, & remifentanil.
ketamine & benzodiazepines are less protein bound
propofol appears to be safe
dexmedetomidine cleared by liver
remifentanil- reduced clearance in patients with ESRD
fentanyl has prolonged half-life
87
Patients with ESRD generally require dialysis
24-36 hours after major surgery
88
Uremic patients may require fluid replacement with
red blood cells
FFP
colloid solutions
89
In patients with renal insufficiency, give
preoperative volume replacement
90
Describe the use of succinylcholine in renal failure patients.
increases serum potassium 0.5 mEq/L
succinylmonocholine (precursor to products of metabolism)
cholinesterase deficiency in uremic patients
91
Describe the use of pancuronium in renal failure.
80% excreted in urine
92
Describe the use of atricurium, cisatricurium, and mivacurium in renal failure patients.
duration not increased in renal failure
| slower onset with cisatricurium and mivacurium
93
Describe the use of vecuronium in renal failure patients.
approximately 30% excreted via renal system
| effects rapidly reversed with dialysis
94
Describe the use of rocuronium in renal failure patients
renal failure reduces clearance by almost 40%
| & has longer DOA
