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Basics - Positioning

Lecture 2. Basics of Anesthesia

The underlying pathological mechanisms behind nerve injuries are (there are 6): Stretch Compression Generalized ischemia Metabolic derangement Laceration Direct trauma
According to the ASA Closed Claims Project database, ______ is the second most common class of injury perioperative nerve injury (16%)
Which patients are at increased risk for nerve injuries? (there are 6) Obese patients Thin patients Diabetic Peripheral vascular disease Peripheral neuropathy An anatomic variable (eg, cervical rib)
Goals that Anesthetists should have when positioning the patient (there are 5): Maximize surgical exposure. Prevent injury. Maintain physiologic functioning. Provide access for patient assessment, monitoring, and anesthetic intervention. Allow return to preoperative levels of health and activity.
The most commonly used position for all surgical procedures is: supine
What is the most common positional injury pf the upper extremities? postoperative ulnar neuropathy
Supine position is also called _______ or ______ dorsal recumbent or horizontal
Cardiovascular changes related to supine position includes Bainbridge reflex, which is ... Increase in HR secondary to Increased right-sided filling pressures, which increases cardiac output. Baroreceptors stimulated to decrease HR and PVR; BP returns to normal.
Ventilator changes include a decrease in FRC, which is _______ + ________, and can lead to __________ (3 things) - FRC = expiratory reserve volume (1200 mL) + residual volume (1200 mL)(volume of gas that remains in the lungs after passive exhalation) - atelectasis, postoperative hypoxia and infection
With general anesthesia the diaphragm and intercostals relax, which causes a ____ to _____% decrease in FRC 15 - 20%
In supine positioning: Spontaneous ventilation favors _______ lung segments. Controlled ventilation favors _______ lung segments. dependent; independent
The most common ocular injury is..... corneal abrasions
Edentulous patients, those with large faces, or requiring two hands for a proper mask fit can incur additional pressure on the _____ nerve during masking. facial nerve
The motor root of the _____ nerve may also be damaged from traction on the angle of the mandible facial
Extreme flexion at the elbow also leads to damage of what nerve? ulnar nerve
Brachial plexus is formed by which nerves? C5 - C8, T1
How is the brachial plexus divided? Roots (5) branches off into trunks (3), which branch off into divisions (6), which branches off into cords (3), which branches off into terminal branches (5)
The brachial plexus responsible for the motor innervation of .... all of the muscles of the upper extremity
The brachial plexus supplies ... all of the cutaneous innervation of the upper limb, except the area of the axilla and dorsal scapula.
The second most common postop neurological injury is to the ... brachial plexus
Which 3 structures are relatively close in proximity to the brachial plexus, therefore predisposing the brachial plexus to risk of compression against these structures? relatively fixed first rib, clavicle and humerus
Pronated arm causes damage to _______ nerve ulnar
Abduction of the arm greater than 90 degrees causes risk to ________, which causes inability to ______ (abduct or adduct) brachial plexus, abduct
The ulnar nerve originates from the _____ (dorsal or ventral) nerve root of ______ and the _____ (dorsal or ventral) nerve root of ______. ventral nerve roots of C8 & T1; dorsal nerve root of C8
How many perioperative nerve injuries involve the ulnar nerve? more than a quarter
Risk factors associated with increased risk of ulnar nerve injury are (there are 6): Hypotension Use of automated blood pressure cuffs Subclinical diabetes or other unrecognized medical illness Local anesthetic toxicity Manipulations of the brachial plexus during surgery Stretch or compression during surgical positioning
The blood supply to the ulnar nerve is susceptible to compression from the tubercle of _______, due to the artery’s _____(superficial or deep) course in the _____(proximal or distal) forearm. coronoid process superficial proximal
Ulnar injury causes inability to _____ or ____ the 5th finger, decreased sensation over both surfaces of the _____ and _____ fingers, resulting in ______ hand abduct or oppose medial ring & pinky fingers claw hand
Injury to radial nerve results in (4 things): Wrist drop Inability to extend the metacarpophalangeal joints Weakness in abduction of the thumb Decreased sensation over dorsal surfaces of the lateral first, middle, and ring fingers
Injury to the _____ nerve may occur during an IV start either by the needle or extravasation of the drug median
Injury to the median nerve results in (2 things): Inability to oppose the 1st and 5th digits Decreased sensation on the palmar surface of the lateral first, middle, and ring fingers.
Injury to the musculocutaneous nerve results is (2 things): Inability to flex the arm Decreased sensation over the ventral surface of the forearm
Decreased sensation on the palmar surface of the lateral first, middle, and ring fingers is from injury to the ______ nerve. Decreased sensation over dorsal surfaces of the lateral first, middle, and ring fingers is due to injury to the _____ nerve median nerve, radial nerve
Lying supine has what affect on the lumbar spine? How can this be treated? loss of lumbar curve Provide a small support device (roll, pad) in the lumbar region before induction may help retain lordosis and make patient with known lumbar distress more comfortable
Crossing of legs causes damage to the ______ of the dependent leg in an anesthetized patient superficial peroneal nerve
Crossing of legs causes damage to the ______ of the independent (top) leg in an anesthetized patient sural nerve
After supine, the most commonly used position is: lithotomy
Lithotomy position is used for what patients (there are 3)? for patients undergoing urological, GYN, and colorectal procedures
Legs must be elevated and lowered simultaneously to prevent ... (3 things) hip disarticulation, torsion injury to relaxed muscles and ligaments, and spinal injury
How is vital capacity affected in lithotomy position? What is vital capacity? decreased Vital capacity (4800 mL) = inspiratory reserve volume (3100 mL) + tidal volume (500 mL) + expiratory reserve volume (1200 mL)
What cardiovascular changes occur when legs are elevated in lithotomy position? When legs are lowered in lithotomy position? Autotransfusion from leg vessels increases circulating blood volume and preload. Increases 100-250 mL per lower extremity elevated. Lowering the legs has the opposite effect; causes hypotension.
The _____ and ______ are particularly at risk of compression injury as they wind round the neck of the fibula and medial tibial condyle common peroneal nerve and saphenous nerve
In lithotomy position extreme flexion of the hip joints can cause neural damage by (2 things): Stretch - sciatic and obturator nerves. Direct pressure - compression of the femoral nerve as it is passes under the inguinal ligament
#1 lower extremity nerve to be damaged intraoperatively is: common peroneal nerve
Injury to this nerve is from Hip flexion of > 90 degrees, which results in arterial or venous occlusion & nerve palsy femoral nerve
Injury to this nerve is occurs with hip flexion, which results in weakness or paralysis of adduction of the thigh. Damage during difficult forceps delivery or excessive flexion obturator nerve
_______ injury is due to stretching, most likely to occur if improperly positioned in lithotomy sciatic nerve
______ injury is from compression of medial aspects of calf rest on stirrups saphenous nerve
Injury to this nerve results in foot drop, inability to evert the foot, sensory loss to dorsal area of foot, loss of dorsal extension of toes Common peroneal nerve
Injury to this nerve results in weak plantar flexion, paresthesias of posterior calf, sensory deficit to sole, toes, and lateral foot Posterior tibial nerve
Injury to this nerve can occur in the lithotomy position when compressed by stirrups with excessive pressure on the posterior aspect of the knee Posterior tibial nerve
In lithotomy position _______ is a condition in which increased tissue pressure within a limited tissue space compromises the circulation. compartment syndrome
Compartment syndrome probably due to (3 things): A decrease in perfusion pressure caused by a combination of the weight of extremities against the supportive devices. Reduction in compartment capacity. Elevation of the lower limb above the heart.
The most consistent factor in development of compartment syndromes is: the duration of the procedure
Compartment syndrome can lead to (3 things): muscle necrosis, myoglobinuria & eventual renal damage
The cardiovascular change(s) that occurs due to trendelenberg positioning is/are: Activation of baroreceptors = decreased CO, PVR, HR, and BP.
3 respiratory changes related to trendelenberg positioning are: Decrease in lung capacities from the shift of the abdominal visera. Increased V/Q mismatching, which results in atelectasis. Increased likelihood of aspiration
What affects does trendelenberg positioning have on ICP, CBF and IOP in patients with glaucoma? Increase in ICP Decrease in CBF d/t venous congestion. Increase in IOP in patients with glaucoma
What nerve injury can occur due to trendelenberg positioning? brachial plexus
What 2 nerve injuries can occur due to extreme trendelenberg positioning if the arms become loose? plexus injury or radial nerve injury
Cardiovascular changes related to reverse trendelenberg include decrease in ____, ___, and ___; and increase in ___, ____, and ____ Preload, CO, and arterial BP decrease. Baroreceptors increase sympathetic tone, HR, and PVR
Reverse trendelenberg has an increased risk for _______ if operative site above the level of the heart venous air embolism
3 respiratory changes that occur with reverse trendelenberg are: Spontaneous ventilation requires _____ (more/less) work. FRC ______ (decreases/increases) V/Q mismatch _____(does/does not) occur Spontaneous ventilation requires less work. FRC increases. V/Q mismatch occurs.
What affects does reverse trendelenberg have on CPP and CBF? CPP and CBF may decrease
What 3 procedures are done in sitting position? shoulder surgery, posterior fossa craniotomies, and cervical surgery
What are the cardiovascular changes associated with sitting position? Pooling of blood in the lower body decreases central blood volume. CO and arterial BP fall despite an increase in HR and SVR
What affects does the sitting position have on CBF? CBF decreases
3 respiratory changes that occur with sitting position are: Lung volumes and FRC ______ (decrease/increase) Work of breathing ______(decreases/increases) V/Q mismatch _____(does/does not) occur Lung volumes and FRC increase. If hips are flexed and elevated the diaphragm shifts cephalad and WOB increases. V/Q mismatch occurs
A positioning concern related to sitting position is _______ from stretch on spinal cord when the head is flexed; and ____ (increased/decreased) autoregulation of spinal cord under GA and in the sitting position Quadriplegia decreased autoregulation
To prevent jugular vein obstruction while in the sitting position we must maintain a space of ____ fingers between the mandible and neck Two
With venous air embolus (VAE) ____ displaces ____ in the pulmonary vasculature air displaces blood
If venous air embolus (VAE) occurs patient is to be placed in what position? Place patient in T-berg position on his/her left side
Air that enters the skull but does not leave is called _______ Tension pneumocephalus
The presence of air or gas within the cranial cavity (Associated with disruption of the skull, after head trauma, tumors of the skull base, or after neurosurgery) is called _____ Pneumocephalus
The position that is also known as ventral decubitus is ______ prone position
For procedures on the neck or back, the occipital or postero-lateral cranium, sacral, perianal or perineal the patient will be in _____ prone position
Cardiovascular changes related to prone position are: Femoral vein and IVC compression, which may decrease preload, CO, and BP
What respiratory changes are caused by the patient being in prone position? How is it treated? Compression of abdomen and thorax restricts diaphragm movement, which decreases total lung compliance and increases WOB. With placement of chest rolls = improved pulmonary mechanics
In prone position the arms are placed ____ or ____ in goal post position or at the patient's sides
A specialized table for the prone position that allows the thorax and abdomen to hang freely is the ___________ Jackson Table
_____ Frame is placed over OR table and facilitates venous drainage from lower extremities Wilson Frame
3 potential eye complications from the prone position are: corneal abrasion, blindness or edema
5 potential causes of blindness from prone position are: Obesity, Wilson frame, prolonged surgical time, hypotension, hypovolemia.
In the prone position excessive head rotation can reduce flow in both the _____ and ______ systems on either the ipsilateral or contralateral sides carotid and vertebral systems
The nerve injury that can occur in the prone position is: brachial plexus
Side lying position is also known as: Lateral Decubitus Position
This position is used for procedures in which surgical access to the hemithorax, kidney, retroperitoneal space is needed. Also used for EGDs, ERCPs and colonoscopies, etc Lateral Decubitus Position
In lateral decubitus position, how is ventilation & perfusion affected in an awake pt vs intubated pt? Awake pts: dependent lung will have increased perfusion & ventilation Anesthetized pts: dependent lung will have increased perfusion, but decreased ventilation = V/Q mismatch
In lateral decubitus position there is ____ increased/decreased) FRC and _____ (increased/decreased) volume in both lungs Decreased FRC Decreased volume both lungs
What affects does lateral decubitus position have on CO & BP? CO unchanged unless venous return is obstructed (ex kidney rest). BP may fall as a result of decreased vascular resistance.
Created by: Thommy413