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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_612_Библиотеки_им_академика_М_И_Перельмана
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FIGURE 11.3. The ear, its sensory nerves, and cutaneous dermatomes.
With the growth of peripheral nerve and migraine surgery in the head and neck region,
minor nerve blocks have evolved to provide both diagnostic and therapeutic effects. Nerve
blocks have been demonstrated to identify migraine trigger sites with a positive predictive
value of 0.89.36 In this process, terminal branches of the trigeminal nerve are targeted with
local anesthetic injections. The patient then reports the resulting migraine intensity within 12
hours after administration of the block. If the patient’s pain intensity decreased to 0 or 1 out
of 10, the block was considered successful in identifying the trigger site for surgery.
36
Hand Blocks
Minor nerve blocks provide the standard for procedural anesthesia in the hand and wrist.
The use of peripheral nerve blocks allows for near-complete treatment of hand injuries and
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pathologies in the emergency room, office, office-based operating room, or operating room
without the need for endotracheal intubation. Furthermore, the anatomy of the upper
extremity can anesthetize at multiple levels and segments because of the minimal variation
in dermatomal innervation of the extremity to achieve accurate and controlled delivery of
anesthesia for only the targeted segments with the potential to deliver near-complete
anesthesia.
Traditionally, hand surgery has used nerve blocks in conjunction with tourniquets to
provide an anesthetized bloodless field for optimal operative conditions. However, current
trends in using anesthetic agents with epinephrine in hand surgery have shifted from
tourniquet procedures to wide-awake local anesthesia no tourniquet (WALANT)
procedures. WALANT initially saw acceptance in soft-tissue procedures such as trigger
finger or open carpal tunnel releases. However, with the development of new techniques,
WALANT has expanded to bony procedures including the treatment of finger/hand
fractures, wrist fractures, proximal interphalangeal joint, and metacarpophalangeal joint
arthroplasty as well as even more extensive soft-tissue procedures such as a spaghetti
wrist.1 Patient satisfaction is quite high with these procedures as patient anxiety, comfort,
and satisfaction are equal or higher with WALANT as compared to traditional procedures
performed with sedation.1 Additionally, studies demonstrated that postoperative pain is
equivalent or better controlled with WALANT with equivalent to lower use of postoperative
narcotics.37 Essential to the success of WALANT is a cooperative patient who can tolerate
wide-awake anesthesia and the ability to achieve high levels of anesthesia simply with
minor nerve blocks.
Anesthesia within individual fingers may be accomplished with minor nerve blocks of the
individual digital nerves that are present on both the ulnar and radial aspect of each finger
(Figure 11.4). There are many methods by which to induce anesthesia within a digit. Some
practitioners advocate individual injection of the radial and ulnar aspect of a digit at either
the proximal interphalangeal joint or metacarpophalangeal joint level to individually
anesthetize the radial and digital nerves, respectively. A single injection may be used at the
level of the A1 pulley of the hand to simultaneously anesthetize both nerves and possibly
the common digital nerves of multiple fingers. Occasionally, a dorsal infiltration will also be
required to provide dorsal coverage.
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FIGURE 11.4 Location of nerves in the hand and wrist and where to perform
blocks. A. The expected location of the digital nerves branching from the
common digital level in the hand at the level of the A1 pulley. * indicates the
injection site for a single injection digital nerve block. B. Location of the median
and ulnar nerves. From radial to ulnar, the indicated structures are the radial
artery (red), median nerve (yellow), palmaris longus (white), flexor carpi ulnaris
(white), ulnar artery (red), and ulnar nerve (yellow). * denotes the location of
injection for a median nerve block just ulnar to the palmaris longus tendon. The
black arrow denotes the injection direction for an ulnar nerve block just below the
flexor carpi ulnaris and ulnar to the ulnar artery. C. Location of radial sensory
nerve, with white arrow denoting the location of radial nerve block at the radial
styloid.
Median nerve blocks are traditionally performed at the level of the wrist crease, signifying
the entrance of the nerve in the carpal tunnel (Figure 11.4). The puncture is traditionally
made just ulnar to the palmaris longus tendon as the median nerve normally rests radial or
just beneath this tendon. If the patient reports paresthesia upon puncture but prior to
injection, the needle should be removed and reinserted more ulnarly as the paresthesia
likely indicates intraneural positioning. To ensure complete safety, the block may be
performed with ultrasound guidance to confirm appropriate and safe positioning.
The ulnar nerve is located deep to the flexor carpi ulnaris tendon and lies with the ulnar
artery with the nerve ulnar to the artery. As it enters the carpus, it traverses the canal and
gives off the deep motor branch and sensory branches. The dorsal branch of the ulnar
nerve leaves the main trunk of the ulnar nerve approximately 6 to 8 cm proximal to the
ulnar styloid and supplies sensation to the dorsal-ulnar aspect of the hand. Ulnar nerve
blocks are traditionally performed at the wrist as demonstrated in Figure 11.4. It is important
to aspirate prior to injection to ensure that intravascular injection into the ulnar artery does
not occur.
The sensory branch of the radial nerve descends the forearm under the tendon of the
brachioradialis and pierces the deep fascia 6 to 9 cm proximal to the radial styloid. It then
moves to a subcutaneous location overlying the first dorsal compartment. The sensory
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branch of the radial nerve may be anesthetized via injection of local anesthetic around the
radial styloid. Again, it is important to aspirate prior to injection as the cephalic vein may be
located in close proximity.
REGIONAL BLOCKS
Regional nerve blocks can provide complete motor and/or sensory nerve blocks to large
portions of the body for completing procedures that otherwise would require general
anesthesia and intubation. Regional anesthesia works via the anesthetic blockade of a
proximal nerve whose dermatomal and motor distribution may cover an entire extremity or
large central portion of the body. Regional blocks provide high-quality analgesia with low
levels of PONV and low rates of unplanned hospital admission.29 These procedures are
most commonly performed with the assistance of ultrasound guidance to correctly identify
the targeted nerve as the nerve often runs as part of a neurovascular bundle. Examples of
regional blocks performed as anesthesia for plastic and reconstructive surgical procedures
include brachial plexus, transversus abdominis plane (TAP), femoral nerve, spinal, epidural,
pectoralis nerve, and/or paravertebral blocks. These blocks may be used to provide
procedural anesthesia with or without the requirement of sedation.
TAP Block
TAP blocks have become increasingly popular to provide regional anesthesia to the torso.
These blocks have gained popularity for plastic surgical procedures including abdominally
based breast reconstruction techniques, abdominoplasty, abdominal hernia repairs, and
abdominal wall reconstructions. The block is performed via injection of anesthetic into the
plane between the transversus abdominis (TA) and internal oblique muscles, or in the case
of subcostal TAP block, between the TA muscle and the posterior sheath of the rectus
abdominis muscles as the neurovascular bundles of the abdominal wall run within these
planes. The abdominal wall is innervated by the branches of the intercostal nerves, which
run in the lateral abdominal wall on the superficial surface of the TA muscle before piercing
the posterior rectus sheath at its lateral margin at the linea semilunaris. TAP blocks may be
performed preoperatively, postoperatively, or intraoperatively in conjunction or without
general anesthesia. When performed preoperatively, they are often performed under
ultrasound guidance, whereas intraoperatively, via direct visualization to provide
postoperative analgesia. Patients who receive TAP blocks demonstrate decreased
postoperative narcotic use, improved pain scores, and earlier return of gastrointestinal
function.38 Additionally, postoperative pain catheters may be placed in the TAP to provide
continuously infused local anesthetic block in the postoperative period.
As TAP blocks are performed within close proximity of the abdominal musculature, which
is well vascularized, there is significant risk of LAST with these blocks. The time to peak
plasma concentration following a TAP block is usually 30 minutes, but may be as long as
90 minutes.4 Epinephrine reduces the systemic absorption, and therefore, larger anesthetic
amounts can be infiltrated (Table 11.4). Because of the high vascularity of the infusion
plane and the low adipose tissue content, the American Society of Regional Anesthesia
and Pain Medicine recommends that dosing be based on lean body weight as opposed to
measured body weight.
39
Paravertebral and Pectoralis Nerve Blocks
Paravertebral and pectoralis nerve blocks represent regional anesthetic techniques that are
used in reconstructive and esthetic breast surgery. Pectoral anesthesia occurs via
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infiltration of anesthetic around the medial and lateral pectoral nerves. These nerves are
located in the plane between the pectoralis major and minor muscles just medial to the
acromion. Sensory blockade can be achieved via intercostal blocks of the second through
fifth intercostal nerves, which may be reached in the intercostal spaces. Blocking the
intercostal nerves lateral to the anterior axillary line will anesthetize both the lateral and
medial intercostal perforating cutaneous nerves. Paravertebral blocks involve injection of a
local anesthetic into the space just lateral to the emergence of spinal nerves from the
intervertebral foramina. Nerve blockade is achieved in dermatomes above and below the
injection site. These blocks can be used for intraoperative anesthesia with sedation and for
postoperative analgesia. They demonstrate high effectiveness with statistically significant
reductions in opioid consumption, postoperative pain, PONV, and duration of hospitalization
reported.
40
Upper Extremity Regional Anesthesia
Regional blocks of the upper extremity allow highly invasive procedures of the arm, elbow,
forearm, wrist, and hand to be performed without intubation. Tourniquets may be applied
and tolerated for extended periods of time all while the patient remains comfortably sedated
during the procedure. The types of procedures that can be performed under successful
brachial plexus block are identical to those performed under general anesthesia including
but not limited to fracture fixation, complex soft tissue repairs, tendon repairs, peripheral
nerve surgery, and even free tissue transfers. Regional anesthesia of the upper extremity is
achieved via infiltration of anesthetic around the brachial plexus. The area of anesthesia
can be tailored to the surgical field by selecting different areas of the plexus for blockade.
For example, surgery of the shoulder often requires and interscalene level block, whereas
procedures of the hand, forearm, and wrist may use axillary, supraclavicular, or
infraclavicular level blocks to maintain shoulder function. As the brachial plexus is located in
close proximity to vascular structures, these anesthetic procedures are often performed by
anesthesiologists under ultrasound guidance to ensure accurate placement of the
anesthetic without vascular injury (Figure 11.5).
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FIGURE 11.5. Supraclavicular Regional block. A. Ultrasound-guided placement
of the catheter above the clavicle. B. Ultrasound image of the block
demonstrating needle placement, the location of the nerves of the supraclavicular
plexus, and the subclavian artery.
Regional anesthesia for upper extremity surgery demonstrates a number of advantages
over traditional anesthesia. Patients report improved immediate postoperative analgesia,
shorter time to ambulation, earlier hospital discharge, and fewer unplanned hospital
admissions and are often able to bypass phase I of the postanesthesia care unit.
29
However, it is important to note that overall narcotic consumption remains unchanged when
compared to general anesthetic patients at 24, 48, and 72 hours.29 Therefore, the benefits
of such anesthesia are largely present only in the immediate postoperative period.
Contraindications to upper extremity regional anesthesia are rare but may include
patients currently on anticoagulation, patients with anesthetic allergies, and patients who
will undergo procedures where complete motor and/or sensory blockade is undesirable.
Examples of procedures where regional blockade is undesirable would include nerve
surgery such as nerve transfers where motor fascicle identification requires accurate
stimulation of the nerve to identify the correct regions to be transferred and procedures
where the patient is asked intraoperatively to move the extremity (eg, tenolysis
procedures).
PROCEDURAL SEDATION
Procedural sedation is a drug-induced depression of consciousness by which painful
diagnostic and therapeutic procedures are made tolerable for patients.41 Sedation induces
a state of reduced anxiety and reduced pain with partial or complete amnesia increasing
patient comfort. Plastic surgeons have been some of the leaders in expanding procedural
sedation from monitored anesthesia care in the hospital-based operating room to officebased procedures. The ability to induce a state of depressed consciousness allows
practitioners to expand the repertoire of offerings to patients in multiple clinical settings.
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However, procedural sedation also has the potential to cause significant morbidity and
mortality.
The American Society of Anesthesiologists describes a continuum of sedation
categorized into three levels.41 Minimal sedation is described as a drug-induced state of
cognitive impairment, but one in which patients retain airway reflexes, ventilation, and
cardiovascular function. Moderate sedation produces a state of depression of the CNS but
with maintenance of purposeful responses to verbal or painful stimuli. The drugs used with
this level of sedation should carry a therapeutic index large enough so that the rendering of
loss of consciousness is unlikely. The airway is typically unaffected and spontaneous
ventilation remains intact. Deep sedation describes a state where the patient does not
respond to verbal or painful cues. The patient may require interventions to maintain an
airway and ventilation. As the level of sedation increases, the risk of adverse events
including mortality increases as well.
The level of required sedation should be titrated to the specific procedure that is being
performed as well as to the physiology of the individual patient. Practitioners should use the
lowest level of sedation that can be safely administered to minimize risk. Preoperative
assessment is essential to properly stratify patients and ensure sedation is delivered safely.
The presence of other comorbidities including heart disease, cerebrovascular disease,
pulmonary disease, renal failure, liver failure, and morbid obesity can significantly increase
the occurrence of major complications. Patients must be monitored appropriately during the
procedure. Current guidance notes the need for pulse oximetry, ECG, and automated
noninvasive blood pressure monitoring.41 Supplemental oxygen should be provided from
induction to discharge. Ventilation monitoring is recommended with waveform capnography
if1 deep sedation is performed2; ventilation cannot be directly visualized3; multiple drugs are
used; or4 preoperative assessment identifies high-risk individuals.
Practitioners of procedural sedation must understand the classes of drugs used to
depress consciousness. Currently, procedural sedation is typically performed utilizing five
classes of drugs: sedative-hypnotics, analgesics, dissociative sedatives, inhalational
agents, and antagonists. Sedative-hypnotics include benzodiazepines (eg, midazolam,
diazepam, lorazepam), barbiturates (eg, pentobarbital), propofol, chloral hydrate, and
etomidate.42 Often the sedative hypnotics are used in conjunction with narcotics to promote
simultaneous sedation and analgesia. Sedative hypnotics and opioids are often
administered via intravenous infusion and titrated based on patient’s response. Medications
may be administered orally, rectally, transnasally, and via intramuscular injection; however,
dose titration with these routes remains less reliable than when they are given
intravenously.
42
Ketamine uniquely causes dissociative sedation characterized by profound analgesia,
sedation, amnesia, and immobilization. It is also characterized by reliable dosing when
given either intramuscularly or intravenously, making dosing easier in office- and
emergency room–based procedures. At doses below 1 to 1.5 mg/kg intravenously and 3 to
4 mg/kg intramuscularly, ketamine is limited to analgesia and sedation. However, above
these critical doses, the dissociative state is reached and appears abruptly. From the time
of injection, ketamine begins to have effects within 45 seconds of administration with the
dissociative sate appearing as early as 1 minute after injection if the critical dosing
threshold is met. The effect lasts for 25 to 30 minutes, allowing procedures to be performed
consistently especially in pediatric patients in the emergency room. Ketamine can induce
parasympathetic behaviors such as salivation, and therefore, anticholinergics may be given
simultaneously. The safety profile of ketamine is quite high as it preserves protective airway
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reflexes, and in 30 years of use, there have been no reports of clinically significant
aspiration events in patients undergoing ketamine anesthesia.
42
Propofol and etomidate are third-generation agents that are ultra-short acting with rapid
onset and brief duration. Both agents cause respiratory depression and apnea. The rapid
recovery makes them excellent candidates for procedural sedation as the patients are quick
to recover protective airway reflexes and return to their nonsedative state after cessation.
Propofol has low rates of PONV but additionally causes hypotension from direct negative
inotropy, vasodilation, and venodilation. Etomidate also may cause myoclonus and
vomiting, so fasting prior to anesthesia is important if this agent is to be used.
If procedural sedation is to be used, antagonists must be present to reverse oversedation
or respiratory sedation. Opioid antagonists such as naloxone can be administered
intramuscularly, subcutaneously, or even sublingually. Naloxone causes complete reversal
of narcotics when administered, therefore persistent pain may occur after treatment.
Multiple doses may be required to completely reverse dangerous respiratory depression
induced by opioids. Nalmefene is a long-acting opioid antagonist with a half-life of 4 to 8
hours. This extended half-life makes it a good candidate for patients who suffer from
fentanyl overmedication as its half-life is longer than that of fentanyl. Flumazenil is a
benzodiazepine antagonist that reverses respiratory depression and sedation induced by
benzodiazepines. Rapid reversal with this agent may lead to sympathetic storm and seizure
activity. These reversal agents should not be routinely administered, but reserved for
serious oversedation and respiratory depression when a patient does not respond to verbal
or noxious stimuli.
In conclusion, procedural sedation allows for the completion of plastic surgical
procedures in both a hospital and office-based setting. Practitioners must be familiar with
the effects of individual agents as well as reversal agents to provide a safe and effective
procedural environment. Utilizing these techniques, a wide-variety of procedures may be
safely accomplished to maximize patient care, comfort and outcomes.
QUESTIONS
1. A pediatric patient weighing 10 kg presents to the emergency room with a facial
laceration. The patient requires repair of the laceration in the emergency room. The
emergency room physician will sedate the patient with ketamine. What is the
maximum volume of 1% lidocaine with epinephrine that can be used as infiltrative
anesthesia?
a. 5 mL
b. 6 mL
c. 7 mL
d. 10 mL
e. 8 mL
2. A patient underwent an abdominoplasty procedure. For added pain control, the
surgeon performs a transversus abdominis plane (TAP) block. In which plane is the
local anesthetic injected in this block?
a. Internal and external obliques
b. Internal oblique and transversus abdominis
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c. Transversus abdominis and peritoneum
d. Rectus abdominis and posterior sheath
e. Intra-abdominally
3. A 35-year-old man was carving wound with a knife when it slipped and he suffered a
laceration to the palmar aspect of the hand. On exam, the patient remains
neurovascularly intact and he has full range of motion. X-ray reveals no fractures of
foreign bodies. The laceration is linear and clean. After providing a tetanus vaccine
and irrigating out the wound, the plan is for closure in the emergency department.
The area is infiltrated with lidocaine with epinephrine and the finger is slightly
blanched. What should be done next?
a. Complete the repair and allow the local anesthetic with epinephrine to wear off
b. Stop the repair and release the sutures to allow reperfusion of the finger
c. Administer phentolamine
d. Infiltrate with more local anesthetic
e. Initiate leech therapy
4. A patient weighing 75 kg undergoing facelift is administered a preoperative local
anesthetic formulation of 0.25% bupivacaine, 1% lidocaine, and epinephrine. Shortly
after subcutaneous infiltration, but before incision, the patient goes into cardiac
arrest. Anesthesia begins supportive measures with 100% FiO2 administered
endotracheally, diazepam is administered, and chest compressions are commenced.
It is hypothesized that the cardiac arrest is because of the local anesthetic
administered, and the anesthesiologist is concerned about the duration of
bupivacaine, prolonging the resuscitative effort. Lipid rescue is begun with a 20% IV
lipid emulsion. What is the appropriate initial dose of this medication in this setting?
a. A continuous drip of 0.25 mL*kg/min
b. 5 mL/kg bolus
c. A continuous drip of 1.5 mL*kg/min
d. 200 mL bolus
e. 100 mL bolus
ANSWERS AND EXPLANATIONS
1. Answer: c. For lidocaine with epinephrine, the maximum dosing is 7 mg/kg.
Therefore, a patient weighing 10 kg can receive 70 mg of lidocaine. As a 1% solution is
10 mg/mL, the patient can receive 7 mL of 1% lidocaine with epinephrine as infiltrative
anesthesia
2. Answer: b. TAP block is administered by blockade of the intercostal nerves, as
they run in the lateral abdominal wall before they pierce the rectus sheath. At this level,
they are found between the transversus abdominis muscle and the internal oblique.
This block is most often administered under ultrasound guidance, by the anesthesia
team.
3. Answer: a. Previously, there were significant concerns about utilizing epinephrine
in proximity to end arteries with small-caliber vessels (eg, fingers, toes, penis, nose,
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and ears). The fear was that the vasoconstrictive effects of epinephrine on the end
arteries would result in potentially critical ischemia and subsequent necrosis of these
appendages. Current evidence demonstrates the contrary. Epinephrine is safe to use
in the vicinity of end arteries with extremely low rates of complications noted with their
use. The blanching of the finger in this clinical vignette should be observed as it usually
will subside with time. The need to use phentolamine is extremely rare as the
epinephrine will usually wear off on its own without the need for intervention.
4. Answer: d. The algorithm for lipid emulsion is seen in Figure 11.1. The initial
dosing is a 100 mL bolus of 20% lipid emulsion if the patient weighs more than 70 kg.
An infusion should then begin at 200 to 250 mL over 15 to 20 minutes.
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5. Garmon EH, Huecker MR. Topical, Local, and Regional Anesthesia and Anesthetics.
StatPearls; 2023.
6. Denkler K. A comprehensive review of epinephrine in the finger: to do or not to do. Plast
Reconstr Surg. 2001;108(1):114-124.
7. Wilhelmi BJ, Blackwell SJ, Miller JH , et al. Do not use epinephrine in digital blocks: myth
or truth? Plast Reconstr Surg. 2001;107(2):393-397.
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