Anesthesia for General Surgery Part 1 Flashcards
The preoperative anesthetic evaluation gives you the information you need to
make decisions regarding risk assessment and perioperative management
As a provider in the preoperative evaluation, we are responsible for
determining medical status of the patient
developing a plan of anesthesia care
reviewing with the patient the proposed plan of care
List the different types of anesthetic techniques:
MAC, general, regional, peripheral nerve block
The ideal anesthetic:
promotes patient safety and satisfaction, good operating conditions for the surgeon, rapid recovery, avoidance of postoperative side effects, low in cost, allows early discharge from PACU, optimizes pain control, allows for optimal OR efficiency
Advantages of general anesthesia include:
rapid onset of unconsciousness, controlled ventilation, allows for paralysis, lower failure rate, more safely allows for positioning extremes
Disadvantages of general anesthesia include:
PONV, postoperative sedation, increased stress response, full stomach-risk for aspiration
Monitored anesthesia care may lead
to unplanned general anesthetic (due to loss of ability to respond purposefully)
Advantages of peripheral nerve blocks include
good option for superficial operations of extremities
consciousness
protective upper airway reflexes
isolated anesthetic effect (good for patients with pulm/CV disease)
Disadvantages of peripheral nerve blocks include
unpredictable sensory and motor anesthesia, success rate related to experience of provider, patient cooperation
Advantages of regional anesthesia for general surgery include
maintenance of consciousness, skeletal muscle relaxation, contraction of GI tract, lower insufflation pressure, decreased stress response, faster recovery
Benefits to a spinal include:
less time to perform, rapid onset sensory/motor anesthesia, less pain
Benefits to an epidural include:
lower risk of post-dural puncture headache, less hypotension, catheter that can provide postop analgesia
Disadvantages of regional anesthesia for general surgery include:
occasional failure to produce adequate levels of sensory anesthesia
hypotension d/t SNS blockade (worse with hypovolemia)
For the maintenance of anesthesia, drug selection is based on
specific goal that is relevant to the drug’s known pharmacologic effects at therapeutic doses
Brain function monitoring (BIS) may help in
titrating dose of inhaled/injected anesthetic drugs to produce desired degree of CNS depression
Maintenance of anesthesia is important for providing
amnesia, analgesia, skeletal muscle relaxation, and control of sympathetic nervous system responses
WIth monitored anesthesia care, we are
held to the same standard as any other anesthetic technique
Goal of positioning is to
ensure patient safety
Positioning concerns include
peripheral nerve injuries, hypotension from impaired venous return, oxygen desaturation due to V/Q mismatch
The best way to position a patient is
a position in which the patient would tolerate when awake
Positioning keys include:
peripheral joint extremities are well padded, support normal lumbar spine curvature, head midline, no pressure on eyes, safety straps/prevent falling
CV considerations with positioning include:
central, regional, and local mechanisms can blunt the effects of position changes to maintain perfusion to vital organs
- erect to supine–> increased venous return–> preload, stroke volume and CO augmented
- mechanoreceptors–> decrease sympathetic outflow
CV considerations regarding atrial reflexes include
atrial reflexes activated to regulate renal sympathetic activity
Increased arterial BP activates
afferent baroreceptors from aorta and within carotid sinuses–> decrease sympathetic outflow/increase parasympathetic impulses to SA node–> decreased HR, stroke volume, and CO
When a patient is anesthetized and positive pressure ventilation is being used,
there is abnormal diaphragm shape, decreased V/Q matching, decreased arterial PO2
adequate minute ventilation limits atelectasis
Any position that limits movement of diaphragm, chest wall or abdomen
may increase atelectasis or intrapulmonary shunt
Pulmonary considerations when using neuraxial anesthesia include
loss of abdominal/thoracic muscle function in dermatomes
retained diaphragmatic function
Arterial BP is labile immediately following
immediately following induction and positioning
CV considerations- GA, muscle relaxation, PPV, and neuraxial blockade interfere with
venous return to the heart, arterial tone, and autoregulatory mechanisms
CV considerations with spinals & epidurals include
significant sympathectomy (reduced preload/blunted cardiac responses)
Positive pressure ventilation leads to
increased mean intrathoracic pressure and decreased venous pressure gradient leading to decreased CO
The most common position for surgery is
supine
The lawn chair position is
where hips/knees are slightly fixed in supine to take the strain off the lumbar spine
The frog-leg position is
where hips/knees flexed and hips externally rotated
Describe arm placement in the supine position:
abduction less than 90 degrees to minimize brachial plexus injury by caudad pressure in axilla from head of humerus
supinated hand/forearm or kept neutral (ulnar nerve)
pad elbows, IV lines, stopcocks
The most common peripheral nerve injury with supine position includes
ulnar neuropathy
Complications of the supine position include
pressure alopecia, backache (padding of spine or flexion hip/knee), soft tissue ischemia (bony prominences), peripheral nerve injury (ulnar neuropathy is most common), operating room table weight limit
Considerations with reverse trendelenburg include
supine, head tilted upward
facilitates upper abdominal surgery by shifting abdominal contents caudad
detect hypotension due to decreased venous return
reduced perfusion pressure to brain
Considerations with trendelenburg include
tilt head down position
nonsliding mattress
should braces not recommended (brachial plexus injury)
CV effects of trendelenburg include:
increased central venous, intracranial, and intraocular pressures, swelling of face, conjunctiva, larynx, and tongue,
Resp effects of trendelenburg include:
potential postoperative airway obstruction
decreased FRC and pulmonary compliance, In MV, higher airway pressures needed to ensure ventilation, ETT preferred to protect airway from aspiration and atelectasis
The lithotomy position involves
hips flexed 80 to 100 degrees
legs abducted 30 to 45 degrees from midline
legs held by stirrups (candy cane, knee crutch, or calf support style)
The most common nerve injury with lithotomy position is
common peroneal nerve injury due to lateral head of fibula that rests against stirrups
Complications with lithotomy position include:
crush injuries to fingers, lower extremity compartment syndrome, both legs should be raised together/down together
Lithotomy is used for (surgical types)
gynecologic, rectal, and urologic surgeries
Resp. and CV concerns with lithotomy position include
increased preload, reduced lung compliance, decreased tidal volume, increased abdominal pressure
Considerations for the lateral decubitus position include
prevent lateral rotation of neck and stretch injuries to brachial plexus, check ears, eyes, and all pressure points, balanced with anterior and posterior support, flexed dependent leg, arms positioned in front of patient
Lateral decubitus position is used for surgeries of the
thorax, retroperitoneal, and hip
To prevent compression injury to the dependent brachial plexus,
an axillary roll is used in the lateral decubitus position
Resp & CV concerns with lateral decubitus position:
Kidney rest needs to be under the dependent iliac crest or else it can compress inferior vena cava and prevent venous return
can compromise pulmonary function- favors ventilation of nondependent lung and blood flow to under ventilated, dependent lung (gravity)
Considerations for anesthetic managements include
choice of anesthetic, monitoring, foley catheter, evacuation of gastric contents, positioning, emergence/extubation, antiemetics, & pain management
For every 15 cm of height that the arterial BP transducer is moved,
there is a 10 mmHg change in BP
Factors that affect pulse oximetry include
methylene blue & indocyanide as they will show a decrease in SpO2
The anesthesia provider is responsible for coordinating the flip in the prone position except for
when the patient is in Mayfield rigid pins and then the neurologist will stabilize the head
Surgeries performed in the prone position include
posterior spine, buttocks, perirectal area, and lower extremities
Pulmonary concerns in the prone position include
elevated intraabdominal pressure which increases the risk for decreased FRC and pulmonary compliance
