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NUNA 681(pharm) > Deliberate Hypotension > Flashcards

Deliberate Hypotension Flashcards

1
Q

deliberate hypotension is

A

controlled, induced, elective

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2
Q

deliberate hypotension is a reduction of systolic BP to

A

80-90 mmHg

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3
Q

deliberate hypotension is a decrease in MAO to

A

50-65 mmHg in normotensive patients

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4
Q

deliberate hypotension is a __ reduction in MAP

A

30%

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5
Q

benefits of deliberate hypotension

A
  1. reduced blood loss
  2. facilitation of surgical dissection
  3. reduction of oozing beneath skin flaps
  4. prevention of aneurysmal rupture (intracranial, aortic)
  5. reduction in intravascular tension (coarctation of the aorta)
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6
Q

benefits of deliberate hypotension- reduced blood loss

A
  1. conserve blood supply
  2. avoidance of transfusion reactions
  3. decreased transmission of blood-borne disease
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7
Q

benefits of deliberate hypotension- facilitation of surgical dissection

A
  1. microscopic surgical (ENT, intracranial AV malformation)
  2. identification of malignant versus nonmalignant tissue, vital structures
  3. reduction of amount of cauterized tissue, debris and wound infection
  4. reduction in operative time
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8
Q

benefit of deliberate hypotension- reduction of oozing beneath skin flaps

A

better plastics outcome, improved wound healing

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9
Q

indications for deliberate hypotension

A
  1. neurosurgery- cerebrovascular
  2. large orthopedic procedures- total hip arthroplasty, spinal fusions
  3. surgery on large tumors- pelvic
  4. surgery on the head and neck- maxilla-facial, middle ear
  5. plastic surgery
  6. patient in whom transfusion is undesirable
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10
Q

deliberate hypotension contraindications- improved drugs and monitoring have allowed patients who previously would have been excluded __

A

eligible for DH

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11
Q

deliberate hypotension contraindications- relative

A

H/) cerebrovascular disease, renal dysfunction, liver dysfunction, severe peripheral claudication, myocardial infarction or angina

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12
Q

deliberate hypotension contraindications- __volmeia

A

hypo

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13
Q

deliberate hypotension contraindications- __ anemia

A

severe

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14
Q

deliberate hypotension contraindications- untreated

A

hypertension- increased risk of death and morbidity during DH (treatment of HTN returns cerebral autoregulation toward normal- DH safe for medically-controlled HTN)

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15
Q

influences of bleeding perioperatively-

A
  1. arterial
  2. capillary
  3. venous
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16
Q

influences of bleeding perioperatively- arterial

A

related to MAP; abolished by tourniquet, reduced by decreased MAP, HR

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17
Q

influences of bleeding perioperatively- capillary

A

dependent on local flow in the capillary bed- reduced be decreased BP and local vasoconstriction (infiltration)

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18
Q

influences of bleeding perioperatively- venous

A

related to venous return, venous tone and dependent on posture- abolished by spinal or epidural and direct acting vasodilators

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19
Q

methods to achieve hypotension- body positioning

A

operative side above the level of the heart (for each 2.5 cm of vertical height above the heart, the local material pressure is reduced by 2mmHg)

aiding the venous pooling in vasodilator capacitance vessels; head-up position

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20
Q

methods to achieve hypotension- PPV

A

decreased venous return, and thus CO

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21
Q

methods to achieve hypotension- PEEP

A

decreased venous return

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22
Q

methods to achieve hypotension- __ SV and HR

A

decreased

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23
Q

methods to achieve hypotension- tourniquets, monitor duration

A

60 min upper limb and 90 min for lower limb, ischemia can occur in less time than this

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24
Q

methods to achieve hypotension- tourniquets, monitor pressure

A

250mmHg in arm; 300mmHg in leg

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25
Q

methods to achieve hypotension- don’t use tourniquet on

A

sickle cell patients

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26
Q

methods to achieve hypotension- local infiltration with epi

A

local vasoconstriction; concentration 1:200,00 to 1:400,000

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27
Q

methods to achieve hypotension- pharmacologic

A
  1. volatile anesthetic agents
  2. sympathetic ganglionic blockers
  3. alpha-adrenergic blockers
  4. beta-adrenergic blockers
  5. vasodilators
  6. spinal and epidural anesthesia
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28
Q

isoflurane- minimal effect on

A

myocardial contractility at low concentrations

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29
Q

isoflurane- __ effect is readily adjusted

A

vasodilation

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30
Q

isoflurane- great for

A

moderate reduction in BP

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31
Q

isoflurane- less of an effect

A

on ICP than halothane

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32
Q

isoflurane- depresses

A

cerebral metabolism (CMRO2)

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33
Q

isoflurane- minimizes

A

reflex vasoconstriction or tachycardia (CNS depressant)

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34
Q

CO- inhaled agent

A

maintained

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35
Q

CO- IV agent (sodium nitroprusside)

A

maintained

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36
Q

tachycardia- inhaled agent

A

rare

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37
Q

tachycardia- IV agent (sodium nitroprusside)

A

frequent

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38
Q

pulmonary shunting- inhaled agent

A

unchanged

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39
Q

pulmonary shunting- IV agent (sodium nitroprusside)

A

increased

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40
Q

cerebral blood flow- inhaled agent

A

maintained

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41
Q

cerebral blood flow- IV agent (sodium nitroprusside)

A

maintained

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42
Q

cerebral metabolism- inhaled agent

A

decreased

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43
Q

cerebral metabolism- IV agent (sodium nitroprusside)

A

unchanged

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44
Q

cerebrovascular CO2 reactivity- inhaled agent

A

preserved

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45
Q

cerebrovascular CO2 reactivity- IV agent (sodium nitroprusside)

A

impaired

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46
Q

monitoring of EEG and SSEP- inhaled agent

A

may not be possible

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47
Q

monitoring of EEG and SSEp- IV agent (sodium nitroprusside)

A

no interference

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48
Q

hepatic blood flow- inhaled agent

A

maintained

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49
Q

hepatic blood flow- IV agent (sodium nitroprusside)

A

maintained

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50
Q

prolonged recovery- inhaled agent

A

possible, dose and duration-related

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51
Q

prolonged recovery- IV agent (sodium nitroprusside)

A

none

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52
Q

effective- inhaled agent

A

yes

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53
Q

effective- IV agent (sodium nitroprusside)

A

yes

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54
Q

administration- inhaled agent

A

simple

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55
Q

administration- IV agent (sodium nitroprusside)

A

requires infusion pump and setting up solution

56
Q

control- inhaled agent

A

easy

57
Q

control- IV agent (sodium nitroprusside)

A

variable, may be unstable if patient response not carefully gauged

58
Q

fine tune- inhaled agent

A

imprecise

59
Q

fine tune- IV agent (sodium nitroprusside)

A

more precise

60
Q

onset time- inhaled agent

A

4-5 min

61
Q

onset time- IV agent (sodium nitroprusside)

A

variable (1-5 min); quick onset at the expense of possible overshoot

62
Q

recovery time- inhaled agent

A

5-7 time

63
Q

recovery time- IV agent (sodium nitroprusside)

A

very short, 1-2 min

64
Q

rebound HTN- inhaled agent

A

none

65
Q

rebound HTN- IV agent (sodium nitroprusside)

A

yes, can be treated effectively with beta-blockers

66
Q

toxic metabolics- inhaled agent

A

none

67
Q

toxic metabolics- IV agent (sodium nitroprusside)

A

rarely cyanide and thiocyanate toxicity

68
Q

tachyphylaxis- inhaled agent

A

rare

69
Q

tachyphylaxis- IV agent (sodium nitroprusside)

A

rare

70
Q

sevoflurane- shown to minimize

A

the HR fluctuation that occur with use of nitroglycerin, nicardipine, or alprostadil (PGE) to achieve hypotension (decreased sympathetic activity; study looked at combination with nitrous oxide)

71
Q

sympathetic ganglionic blocker- trimethaphan (Arfonad)- interruption of

A

sympathetic outflow, vasodilation

72
Q

sympathetic ganglionic blocker- trimethaphan (Arfonad)- causes

A

urinary retention, mydriasis (mistaken for cerebral ischemia), tachycardia due to parasympathetic block (bleeding), tachyphylaxis

73
Q

clonidine, dexmedetomidine- pretreatment with clonidine po reduced

A

the required infusion of PGE 1 needed to maintain DH and reduces the blood loss by 45%

74
Q

clonidine, dexmedetomidine- use of dexmedetomidine combined with remifentamil

A

to provide controlled hypotension during posterior spinal fusion

75
Q

alpha adrenergic blockers- phentolamine (Regitine), droperidol-

A

vasodilation, increased HR and myocardial oxygen demand due to beta stimulation

76
Q

beta adrenergic blockers- propranolol, atenolol, esmolol, (labetalol): big advantage is

A

decreased HR and CO

77
Q

beta adrenergic blockers- propranolol, atenolol, esmolol, (labetalol): used along with

A

vasodilators

78
Q

beta adrenergic blockers- propranolol, atenolol, esmolol, (labetalol): prevents

A

wide variations in BP (vasospasm re: SAH)

79
Q

beta adrenergic blockers- propranolol, atenolol, esmolol, (labetalol): labetalol is

A

not as potent, no increase in ICP

80
Q

beta adrenergic blockers- propranolol, atenolol, esmolol, (labetalol): labetalol maskes

A

the adrenergic response to acute blood loss (long duration lasts in postop period)

81
Q

beta adrenergic blockers- propranolol, atenolol, esmolol, (labetalol): propranolol pretreatment reduced

A

the dose of SNP and the rebound HTN upon discontinuation

82
Q

beta adrenergic blockers- propranolol, atenolol, esmolol, (labetalol): esmolol reduced

A

plasma renin activity- improved stability; greater reduction in CO

83
Q

sodium nitroprusside-

A

“dial-a-pressure”

84
Q

sodium nitroprusside- good for

A

short procedures

85
Q

sodium nitroprusside- caution

A

increased ICP

86
Q

sodium nitroprusside- cyanide toxicity, monitor

A

acid/base balance

87
Q

sodium nitroprusside- no adverse effect on

A

myocardial contractility

88
Q

sodium nitroprusside- pretreat with

A

propranolol or captopril to reduce dose of SNP and avoid rebound HTN (or enalapril 2.5mg 60 min p)

89
Q

nitroglycerin- less dramatic

A

decrease in BP

90
Q

nitroglycerin- decreases __ more rapidly than _

A

systolic BP

diastolic (maintains flow)

91
Q

nitroglycerin- less rapid

A

recovery

92
Q

nitroglycerin- coronary artery perfusion __

A

better

93
Q

nitroglycerin- __ in some patients

A

less effective

94
Q

nitroglycerin- __ in ICP- caution

A

increase

95
Q

nitroglycerin- 3-in NTG transdermal: reduced blood loss by

A

almost 50% and reduced the need for transfusion of patients having ORIF of femora fractures; “induction of moderate hypotension”

96
Q

spinal and epidural anesthesia- vasodilation of

A

both arterial and venous due to sympathectomy

97
Q

spinal and epidural anesthesia- if T1-T4 are blocked,

A

tachycardia is prevented

98
Q

spinal and epidural anesthesia- used in __ surgery

A

lower abdominal and pelvic; pelvic venous plexuses

99
Q

spinal and epidural anesthesia- if epinephrine is added to the local, the ___ might be counteracted

A

hypotensive effect of the block

100
Q

hypotension- organ function- it might be best to reduce BP by

A

decreasing SVR rather than CO so blood flow to tissues can be maintained

101
Q

hypotension- organ function- __ and __ are the principle hazards of deliberate hypotension

A

ischemia of the brain and myocardium

102
Q

hypotension- organ function- CNS: principle of __ is key

A

autoregulation

103
Q

hypotension- organ function- CNS: “safe” lower limit is __ in normotensive patients because that is the lowest pressure at which autoregulation of CBF is maintained

A

50-55 mmHg

104
Q

hypotension- organ function- CNS: during normotension, CNF changes linearly with __ when __; when the MAP fall below 50mmHg, CBF __

A

PaCO2 when PaCO2 is 20-70mmHg

no longer responds to changes in PaCO2

105
Q

hypotension- organ function- heart:

A

maintain balance between myocardial oxygen supply and demand

106
Q

hypotension- organ function- heart: AVOID

A

tachycardia, myocardial depression, coronary artery perfusion alteration

107
Q

hypotension- organ function- lungs: increased PaCO2 due to

A

increased dead space; must maintain CO with fluid replacement

108
Q

hypotension- organ function- lungs: decreased PaO2 due to

A

increased shunt (seen with use of Nipride, but not with iso; seen with normal lungs, but not with COPD**)

109
Q

hypotension- organ function- lungs: necessitates

A

controlled ventilation, increased oxygenation

110
Q

hypotension- organ function- kidneys: GFR is reduced with

A

MAP falls below 75 mmHg

111
Q

hypotension- organ function- kidneys: metabolic needs of kidneys still met but

A

oliguria occurs

112
Q

hypotension- organ function- kidneys: normovolemia patients

A

have rapid recovery of urine production when hypotension is discontinued (strict maintenance of urine output during deliberate hypotension is not necessary)

113
Q

hypotension- organ function-kidneys: renal function was better preserved with

A

combination of iso and labetalol than with higher concentrations of iso alone

114
Q

hypotension- organ function- splanchnic circulation: liver perfusion is altered due to

A

limited autoregulation for the hepatic artery and no autoregulation for the portal venous circulation

115
Q

hypotension- organ function- splanchnic circulation: increased sympathetic outflow (baroreceptor mediated in response to decrease BP) causes

A

splanchnic vasoconstriction and decreased blood flow to the liver and the intestine

116
Q

hypotension- organ function- eye: decreased blood flow to the eyes causes

A

blurring of vision and rarely blindness

117
Q

hypotension- organ function- eye: position carefully to avoid

A

increased intraocular pressure which would oppose blood flow even further (external pressure; venous congestion- neutral position)

118
Q

hypotension- organ function- eye: maintain

A

Hgb

119
Q

hypotension- organ function- eye: colloid versus crystalloid

A

minimize edema

120
Q

monitoring: ECG

A

signs of inadequate myocardial perfusion like ST depression and ectopic beats

121
Q

monitoring: pulse ox

A

signs of decreased oxygenation and peripheral perfusion

122
Q

monitoring: temp

A

body heat lost more rapidly from vasodilation

123
Q

monitoring: art line

A

beat to beat measurement of BP (allows sampling of ABGs, place transducer at level of internal carotid)

124
Q

monitoring: EtCO2

A

not complete accurate due to increased dead space, decreased CO, and changes in body metabolism

125
Q

monitoring: EtCO2 sudden decrease may indicate

A

pulmonary embolism

126
Q

monitoring: EtCO2 use as guide to

A

avoid hyperventilation which would further decrease CBF

127
Q

monitoring: central venous line

A

fluid replacement and monitor CVP

128
Q

monitoring: UOP

A

especially long cases

129
Q

monitoring: other options

A

evoked potentials, EEG, serum electrolytes, ABGs, Hct

130
Q

complications- __ is not different from that of all anesthetics

A

mortality

131
Q

complications- nonfatal complications

A
  1. CNS related- dizziness, prolonged awakening, cerebral artery thrombosis
  2. retinal thrombosis
  3. anuria, oliguria
  4. postop bleeding
132
Q

complications- __ hypotension

A

inadequate; use second agent

133
Q

complications- __ hypotension

A

excessive

134
Q

type of DH

A
  1. slow onset, sustained moderate hypotension with slow return to normal (plastic, maxilla-facial, ear, nose, throat)
  2. moderate sustained hypotension with reduced HR (when massive blood loss is anticipated)
  3. profound hypotension with short periods of excessively small pressures (clipping cerebral aneurysm)
135
Q

background anesthesia of DH

A
  1. balanced anesthesia
  2. omit atropine
  3. use generous sedation or analgesia
  4. NMB
  5. during hypotension, increase FiO2
  6. continue in PACU- avoid CO2 retention, hypoxia, use patient’s position
136
Q

don’t reduce the systolic BP during the operation to less than

A

preop DBP

137
Q

avoid the severe head-up tilt unless

A

arterial pressure is being measured at the level of the Circle of Willis

NUNA 681(pharm) (12 decks)

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