Chapter 7 Flashcards

1
Q

Who gave the first public demonstration of general anesthesia at Mass Gen?

A

William T.G. Morton on October 16, 1846

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2
Q

What are the “A”s of anesthesia?

A
Amnesia
Anesthesia
Analgesia
Akinesia
Areflexia
Anxiolysis
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3
Q

Amnesia

A

Inability to form memories

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4
Q

Anesthesia

A

Lack of sensation

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5
Q

Analgesia

A

Relief/lack of perception of pain

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6
Q

Akinesia

A

Lack of movement in response to surgical stimulus

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7
Q

Areflexia

A

Blunting of autonomic reflexes- attenuation of reflexic hemodynamic responses to surgical stimulus

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8
Q

Anxiolysis

A

Decrease in procedure-related anxiety

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9
Q

What does the preoperative assessment include?

A

Detailed hx
PE
Review of pertinent data and studies

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10
Q

What are the advantages of a preoperative assessment?

A

Allows further studies to be performed, if indicated

Allows interventions to take place so that the pt may be “optimized”

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11
Q

What is the goal of the preoperative assessment?

A

Summarize the pt’s status to formulate an anesthetic plan

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12
Q

Which active cardiac conditions should be evaluated and treated before noncardiac surgery?

A

Decompensated heart failure
Severe valvular disease
Significant arrhythmias
Unstable coronary syndromes

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13
Q

What procedures are considered to have elevated cardiac risk?

A
Aortic and other major vascular
Peripheral vascular
Anticipated prolonged surgical procedures associated with large fluid shifts and/or blood loss
Carotid endarterectomy
Head and neck
Intraperitoneal and intrathoracic
Orthopedic 
Prostate
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14
Q

What procedures have a low cardiac risk?

A

Cataract

Plastic surgery

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15
Q

What are five clinical predictors of cardiac risk independent of the surgical procedure?

A
Ischemic heart dz
Hx of heart failure
Cerebrovascular dz
Diabetes mellitus
Renal insufficiency
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16
Q

When is perioperative cardiac morbidity increased?

A

In those unable to achieve four METs

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17
Q

What is more predictive of perioperative outcomes than spirometry?

A

Clinical findings and pt exercise capability

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18
Q

In evaluation of the pulmonary system, what diseases should be inquired about?

A
Reactive airway dz
COPD
Tobacco use
Oxygen requirement
Obstructive sleep apnea sx
Recent upper respiratory tract infections
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19
Q

Who is at increased risk of pulmonary complications?

A

FEV1 <70%

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20
Q

When is the highest likelihood of gastric aspiration?

A

Induction

Emergence

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21
Q

When is aspiration more likely during the maintenance phase of anesthesia?

A

If the airway is not protected intraoperatively with an ET tube

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22
Q

What must be in place during heavy sedation?

A

ET tube

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23
Q

What are specific risk factors for aspiration during surgery and anesthesia?

A
Recent ingestion of food (<8 hrs for heavy meals, <6 h for light solid food, <2 h for clear liquids)
Trauma
Gi dysfunction
Increased intra-abdominal pressure
Use of opioids
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24
Q

When does the ACC/AHA recommend continuing beta blockers?

A

HTN
Angina
Symptomatic arrhythmias

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25
When does the ACC/AHA recommend starting beta blockers?
Those undergoing vascular surgery who were found to have ischemia on preoperative testing
26
What does LEMON stand for?
``` Look externally Evaluate the 3-3-2 rule Mallampati Obstruction Neck mobility ```
27
What in the look externally part of LEMON would make for a more difficult intubation?
``` Known face or neck pathology Abnormal face shape Sunken cheeks Receding mandible Narrow mouth ```
28
In the 3-3-2 rule, what would make for a more difficult intubation?
Mouth opening <3 fingers Hyoid-chin distance <3 fingers Thyroid cartilage-mouth floor distance <2 fingers
29
What obstruction can cause a difficult airway?
Pathology within and/or around the upper airways (e.g., epiglottis, abscess, etc.)
30
What are predictors of difficulty with ventilation?
``` Obesity Presence of beard Edentulousness Presence of OSA sx Advanced age ```
31
Possible effects of diuretics on anesthetic course during surgery
Hypovolemia and hypotension | Electrolyte abnormalities and ECG changes
32
Possible effects of ACE inhibitors, certain aniarrhythmics on anesthetic course during surgery
Refractory vasodilation and hypotension
33
Possible effects of antiplatelet agents, anticoagulant agents on anesthetic course during surgery
Possible increased blood loss | Increased risk of epidural hematoma formation on epidural catheter placement or removal
34
Possible effects of insulin, oral hypoglycemics on anesthetic course during surgery
Hypoglycemia, altered level of consciousness
35
What are the possible effects of MAO inhibitors on anesthetic course during surgery?
Life-threatening HTN or hyperthermia when used with sympathomimetics or meperidine
36
Clinical indicators for ordering an EKG
``` Age 50 or older Significant cardiocirculatory dz, current or past DM (age 40 or older) Renal dz Other major metabolic dz Procedure level 5 ```
37
Clinical indicators for CXR
Asthma or COPD that is debilitating or with change of sx or acute episode within past 6 mos Cardiothoracic procedure Procedure level 5
38
Clinical indicators for serum chemistries
``` Renal dz Adrenal or thyroid disorders Diuretic therapy Chemo Procedure level 5 ```
39
Clinical indicators for UA
``` DM Renal dz Genitourologic procedure Recent GU infection Metabolic d/o involving renal function Procedure level 5 ```
40
Clinical indicators for CBC
Hematologic d/o Vascular procedure Chemo Procedure level 4
41
Clinical indicators for coagulation studies
Anticoagulation therapy Vascular procedure Procedure level 5
42
Clinical indicators for pregnancy test
Pts for whom pregnancy might complicate the surgery | Pts of uncertain status by hx
43
Definition of procedure 4
Highly invasive procedure with blood loss >1500 mL | Includes major ortho surgery, reconstruction of the GI tract, and vascular repair without an ICU stay
44
Definition of procedure 5
Similar to procedure 4 except with ICU stay with invasive monitoring
45
What are the standard intraoperative monitors for virtually all anesthetics?
``` Pulse oximeter Noninvasive BP monitoring ECG Temp monitor A means of assessing adequacy of ventilation, usually with an end-tidal CO2 monitor ```
46
What is the gold standard to monitor endotracheal intubation?
EtCO2
47
EtCO2 is how much below arterial CO2?
5-6 mm Hg
48
An increase in the gap of CO2 between the lungs and arteries in the extreme occurs during what two events?
PE | Cardiac arrest
49
What can be detected by a delayed upstroke of the EtCO2 tracing?
An obstruction to expiration, such as bronchospasm
50
Which nerve is usually tested in peripheral nerve stimulation when paralytic agents are used?
Ulnar
51
What is the purpose of the intra-arterial catheter?
Helpful for frequent blood gas and electrolyte monitoring
52
What is the purpose of the central venous pressure monitor?
Surrogate of the Left Ventricular End Diastolic Pressure to monitor intravascular volume
53
What is the purpose of the pulmonary artery catheter
More accurate measurement of LVED volume
54
In addition to anesthesia, what else occurs during the induction phase?
Pt is prexoygenated, or denitrogenated, with 100% oxygen delivered from a face mask with as tight of a seal as possible
55
What is the goal of preoxygenation?
Bring the end-tidal concentration of oxygen >80% with an SaO2 of 100%
56
What is the MOA of most IV agents?
Facilitate GABA pathways in the brain?
57
What are some examples of IV agents?
``` Barbiturates Propofol Etomidate Ketamine Benzos ```
58
What is the most common induction agent currently used in the US?
Propofol
59
When should propofol be used with caution?
Pts with low cardiac reserve
60
What is an additional benefit of propofol?
Antiemetic properties
61
When should etomidate be used?
In pts with compromised hemodynamics
62
What is a side effect of etomidate?
Can suppress adrenal hormone synthesis for up to 5-6 hrs
63
What are benzos usually combined with?
Opiods
64
Why do benzos need to be used in combination with something else?
They have no analgesic properties
65
What is the predominant benzodiazepine used?
Midazolam
66
How can overdose of benzos be treated?
Flumazenil
67
MOA of ketamine
Inhibits thalamocortical pathways and activation of the limbic system
68
When should ketamine be used?
Induction of anesthesia in pts who must maintain spontaneous breathing, pts with reactive airway dz Can be used as an adjunct in pts with chronic pain
69
When is ketamine undesirable? | Relatively contraindicated?
Head injury and/or elevations in ICP | Coronary artery dz or uncontrolled HTN
70
What can be used to decrease the complications of dysphoria and hallucinations in ketamine?
Benzos
71
When are opioids ideal adjuncts?
For pts with compromised cardiac function undergoing cardiac surgery
72
MOA of opioids
Interact with opioid receptors in the CNS and mediate effects on pain, mood, respiration, circulation and bowel and bladder function
73
What are the side effects of opioids?
Direct dose-dependent depression of ventilation Slowed peristalsis and delayed gastric emptying N/V Constipation Urinary retention Morphine and meperidine- histamine release, causing flushing and hypotension
74
What is the standard measure of potency for inhaled anesthetics?
The minimum alveolar concentration (MAC) of a given gas at 1 atmosphere that produces immobility in 50% of subjects exposed to a noxious stimulus
75
What are the inhalational agents commonly used today?
Isoflurane Sevoflurane Desflurane
76
Which inhalational agent is the most insoluble agent in the blood, thereby allowing a very quick onset and offset of anesthesia?
Desflurane | However, it is relatively unsuitable for mask inductions
77
What do volatile anesthetics cause?
``` Dose-dependent cardiac depression Decreases in systemic, pulmonary, and venous vascular resistance Respiratory depression Bronchodilation Decreases in CMRO2 Increases in ICP ```
78
When is sevoflurane use ideal?
Mask induction, especially in peds or in pts without IV agents
79
Use of nitrous oxide
Used only as an adjuvant anesthetic at relatively high inspired concentrations
80
When is nitrous oxide contraindicated?
Pneumo Small bowel obstruction Air embolism Middle ear surgery
81
What are the two major classes of NMB agents?
Depolarizing and | Nondepolarizing agents
82
What is the only depolarizing agent used in the US?
Succinylcholine
83
What are the major advantages of succinylcholine?
Rapid onset provisiono f reliable intubating conditions in 60 secs Duration of action of 3-5 mins
84
What are the adverse effects of succinylcholine?
Release of potassium from muscle- could lead to life-threatening hyperkalemia Malignant hyperthermia
85
What pts are susceptible to life-threatening hyperkalemia d/t succinylcholine use?
Pts with extensive burns Massive tissue injuries Neurologic injuries Neuromuscular d/os
86
What are relative contraindications to succinylcholine?
Pts with intracranial HTN or open orbital injuries | Children
87
What is used to maintain fluids?
Isotonic crystalloids administered at approximately 2 mL/kg/hr
88
How is blood loss replaced?
Crystalloid or colloids until transfusion is necessary
89
How should nondepolarizing NMB agents be reversed?
Acetylcholinesterase inhibitors
90
What else should be given to reverse nondepolarizng NMB agents?
Anticholinergics, otherwise reversal will result in severe bradycardia and possible asystole
91
What must a pt be able to do before extubation?
Breathe on their own Follow commands Demonstrate purposeful movements Protect their airway
92
What are objective criteria for extubation?
Resonable RR (>8 and <30) Adequate tidal volume (<5 mL/kg) PaCO2 <50 mm Hg Hemodynamic stability
93
When does neuraxial anesthesia result in higher rates of graft viability?
Peripheral revascularization Decreased intraoperative blood loss Lower rate of DVT for hip surgery
94
What are some systemic implications of neuraxial anesthesia?
``` Bradycardia Hypotension Mental status changes Postdural HA Epidural hematoma, more likely in pts with increased ICP ```
95
How to treat hypotension as a result of neuraxial anesthesia
Fluid administration Vasoconstrictors Inotropic agents
96
How to treat bradycardia as a result of neuraxial anesthesia
Anticholinergics
97
How to treat postdural puncture HA
Bed rest IV hydration Caffeine If conservative measures fail, epidural blood patch
98
What are two infectious complications of neuraxial anesthesia?
Epidural abscess | Meningitis
99
Sx of epidural hematoma
Backache | LE weakness or numbness
100
What must be continued prior to neuraxial anesthesia? How long? Why?
Ticlopidine- 2 wks prior Clopidogrel- 1 wk prior Increased risk of hematoma
101
Advantages of peripheral nerve blocks over neuraxial blocks
Greater neuraxial stability | Less risk of neurologic injury
102
Complications of peripheral nerve block
Hematoma Block failure Intravascular injection Nerve damage
103
Possible complication of intercostal, interscalen, supra-or infraclavicular nerve block
Pneumo
104
Complication of interscalene block
Phrenic nerve paralysis
105
Relative contraindications to regional nerve blocks
Sepsis Skin infection in area of proposed needle placement Pre-existent neurologic deficit/neuropathy