Nagelhout Ch 40: Anesthesia for Orthopedics
and Podiatry Correct questions and answers
Cefazoline should be given within how long before incision - ANSWER-1 hour
Vancomycin should be given within how long before incision - ANSWER-2 hours
Pneumatic Tourniquet:
The degree of hypoxia & acidosis is partially influenced by _________ - ANSWER-
Duration of insufflation
- For this reason, the inflation device also comes w/ a built-in timer, generally set for 60-
minute increments, w/ an alarm that will sound as a warning when the allotted time has
been exhausted.
Maximum tourniquet time considered safe - ANSWER-2 hours
The pressure to which the tourniquet should be inflated depends on the _______ &
_________ - ANSWER-BP & the shape & size of the extremity
Deflation of the tourniquet results in the release of _________ into the systemic
circulation. - ANSWER-Metabolic Waste
Release of metabolic wastes after the tourniquet deflates can result in ________ (5) -
ANSWER-- Metabolic acidosis
- Hyperkalemia
- Myoglobinemia
- Myoglobinuria
- Renal failure
The deflation may be marked by transient changes in the hemodynamics or pulse ox.
Most of these resolve quickly, except in those patients w/ extreme conditions r/t their
cardiac or vascular status.
Box 40-2: Tourniquets
,Application of a tourniquet for more than ______ causes tourniquet pain & HTN -
ANSWER-60 mins
Box 40-2: Tourniquets
Application for >____ may result in postop neuropraxia - ANSWER-> 2 hours
Box 40-2: Tourniquets
Abolition of somatosensory evoked potentials & nerve conduction occurs w/in _____
(time) - ANSWER-30 min
Box 40-2: Tourniquets - Muscle changes (4) - ANSWER-• Cellular hypoxia develops
within 2 minutes.
• Cellular creatinine value declines.
• Progressive cellular acidosis occurs.
• Endothelial capillary leak develops after 2 hours.
Box 40-2: Systemic effects of Tourniquet *Inflation* - ANSWER-Elevation in arterial &
pulmonary artery pressures develops.
Usually slight to moderate if only one limb is occluded.
The response is more severe in patients undergoing balanced anesthesia that does not
include a potent anesthetic vapor.
Box 40-2: Systemic Effects of Tourniquet *Release* (6) - ANSWER-• Transient fall in
core temperature occurs.
• Transient metabolic acidosis occurs.
• Transient fall in central venous oxygen tension occurs, but systemic hypoxemia is
unusual.
• Acid metabolites (e.g., thromboxane) are released into the central circulation.
• Transient fall in pulmonary and systemic arterial pressures occurs.
• Transient increase in end-tidal carbon dioxide occurs.
*T/F* The ischemic pain associated with tourniquet application is similar to that of
thrombotic vascular occlusion and peripheral vascular disease. - ANSWER-TRUE
, *T/F* Once tourniquet pain begins, it is often resistant to analgesics & anesthetic
agents, despite the anesthetic technique. - ANSWER-TRUE
- At about 45 to 60 minutes after tourniquet pres- surization, patients report various
symptoms associated with dull aching that progress to burning and excruciating pain
that may require general anesthesia.
- Even with a well-controlled general anesthetic at the time of tourniquet inflation,
ischemic pain may begin during this same time interval and may cause increasing heart
rate and blood pressure that require pharmacologic intervention.
Tourniquet Pain:
The burning & aching pain corresponds to the activation of the small, slow-conducting,
_________ fibers. - ANSWER-Unmyelinated C fibers
The pinprick, tingling, & buzzing sensations that frequently accompany tourniquet
application, often even after deflation, correspond to activation of the larger & faster
_________ fibers. - ANSWER-Myelinated A-delta
Which fibers may be more difficult to anesthetize - ANSWER-C Fibers
- As the concentration of LA decreases, the activation of C fibers increases, but the A-
delta fiber activation is still suppressed.
- This means that C fibers may be more difficult to anesthetize than A-delta fibers, and
tourniquet pain therefore seems more consistent with pain sensation carried by C fibers.
The potency of ________(LA?) is enhanced by an increase in the rate of nerve
stimulation and may offer an advantage by lowering the incidence of tourniquet pain -
ANSWER-Bupivacaine
The addition of ________ (3) to local anesthesia solutions have all shown some efficacy
in reducing the incidence of tourniquet pain. - ANSWER-Opioids
Ketorolac
Melatonin
Sedation w/ _______ may also be effective in reducing the incidence of tourniquet pain
- ANSWER-Dexmedetomidine
*T/F* Properly placed tourniquets inflated to appropriate pressures rarely cause injury. -
ANSWER-TRUE
- Excessive tourniquet pressure for a prolonged time may cause postop paresthesias
that are frustrating to treat and very painful.
and Podiatry Correct questions and answers
Cefazoline should be given within how long before incision - ANSWER-1 hour
Vancomycin should be given within how long before incision - ANSWER-2 hours
Pneumatic Tourniquet:
The degree of hypoxia & acidosis is partially influenced by _________ - ANSWER-
Duration of insufflation
- For this reason, the inflation device also comes w/ a built-in timer, generally set for 60-
minute increments, w/ an alarm that will sound as a warning when the allotted time has
been exhausted.
Maximum tourniquet time considered safe - ANSWER-2 hours
The pressure to which the tourniquet should be inflated depends on the _______ &
_________ - ANSWER-BP & the shape & size of the extremity
Deflation of the tourniquet results in the release of _________ into the systemic
circulation. - ANSWER-Metabolic Waste
Release of metabolic wastes after the tourniquet deflates can result in ________ (5) -
ANSWER-- Metabolic acidosis
- Hyperkalemia
- Myoglobinemia
- Myoglobinuria
- Renal failure
The deflation may be marked by transient changes in the hemodynamics or pulse ox.
Most of these resolve quickly, except in those patients w/ extreme conditions r/t their
cardiac or vascular status.
Box 40-2: Tourniquets
,Application of a tourniquet for more than ______ causes tourniquet pain & HTN -
ANSWER-60 mins
Box 40-2: Tourniquets
Application for >____ may result in postop neuropraxia - ANSWER-> 2 hours
Box 40-2: Tourniquets
Abolition of somatosensory evoked potentials & nerve conduction occurs w/in _____
(time) - ANSWER-30 min
Box 40-2: Tourniquets - Muscle changes (4) - ANSWER-• Cellular hypoxia develops
within 2 minutes.
• Cellular creatinine value declines.
• Progressive cellular acidosis occurs.
• Endothelial capillary leak develops after 2 hours.
Box 40-2: Systemic effects of Tourniquet *Inflation* - ANSWER-Elevation in arterial &
pulmonary artery pressures develops.
Usually slight to moderate if only one limb is occluded.
The response is more severe in patients undergoing balanced anesthesia that does not
include a potent anesthetic vapor.
Box 40-2: Systemic Effects of Tourniquet *Release* (6) - ANSWER-• Transient fall in
core temperature occurs.
• Transient metabolic acidosis occurs.
• Transient fall in central venous oxygen tension occurs, but systemic hypoxemia is
unusual.
• Acid metabolites (e.g., thromboxane) are released into the central circulation.
• Transient fall in pulmonary and systemic arterial pressures occurs.
• Transient increase in end-tidal carbon dioxide occurs.
*T/F* The ischemic pain associated with tourniquet application is similar to that of
thrombotic vascular occlusion and peripheral vascular disease. - ANSWER-TRUE
, *T/F* Once tourniquet pain begins, it is often resistant to analgesics & anesthetic
agents, despite the anesthetic technique. - ANSWER-TRUE
- At about 45 to 60 minutes after tourniquet pres- surization, patients report various
symptoms associated with dull aching that progress to burning and excruciating pain
that may require general anesthesia.
- Even with a well-controlled general anesthetic at the time of tourniquet inflation,
ischemic pain may begin during this same time interval and may cause increasing heart
rate and blood pressure that require pharmacologic intervention.
Tourniquet Pain:
The burning & aching pain corresponds to the activation of the small, slow-conducting,
_________ fibers. - ANSWER-Unmyelinated C fibers
The pinprick, tingling, & buzzing sensations that frequently accompany tourniquet
application, often even after deflation, correspond to activation of the larger & faster
_________ fibers. - ANSWER-Myelinated A-delta
Which fibers may be more difficult to anesthetize - ANSWER-C Fibers
- As the concentration of LA decreases, the activation of C fibers increases, but the A-
delta fiber activation is still suppressed.
- This means that C fibers may be more difficult to anesthetize than A-delta fibers, and
tourniquet pain therefore seems more consistent with pain sensation carried by C fibers.
The potency of ________(LA?) is enhanced by an increase in the rate of nerve
stimulation and may offer an advantage by lowering the incidence of tourniquet pain -
ANSWER-Bupivacaine
The addition of ________ (3) to local anesthesia solutions have all shown some efficacy
in reducing the incidence of tourniquet pain. - ANSWER-Opioids
Ketorolac
Melatonin
Sedation w/ _______ may also be effective in reducing the incidence of tourniquet pain
- ANSWER-Dexmedetomidine
*T/F* Properly placed tourniquets inflated to appropriate pressures rarely cause injury. -
ANSWER-TRUE
- Excessive tourniquet pressure for a prolonged time may cause postop paresthesias
that are frustrating to treat and very painful.
