Positioning Flashcards
Peripheral Nerve Injury PNI ASA Closed Claims
1990- 2007
Peripheral nerve injuries (PNIs), although rare represent 22% of claims, second only to death.
Mechanisms of injury: stretching, compression, and ischemia
Pt positioning is always suspected
Although the cooperation of the entire surgical team is required, the position for surgery is largely DICTATED and ACCEPTED or MODIFIED by
Surgeon
Primary role for the CRNA/MD
protect the airway and vascular access and to promote physiologic homeostasis while the pt is in the required position.
Most common PNI
Following All Anesthetic Types
1990 to 2010
Spinal cord injury 25%
Brachial Plexus Nerve Damage 19%
Ulnar Nerve Damage 14%
Most common PNI
Following General Anesthesia
1990 to 2010
Spinal Cord 19%
Brachial plexus 27%
Ulnar Nerve 22%
Purpose of Operative Positioning
Surgical Exposure and/or Surgical Access
Comfort
Patient Safety
But positioning may evoke undesirable physiological changes and cause injuries
Most Common Operative Positions
Supine or Dorsal Decubitus Position Trendelenburg Reverse Trendelenburg Lithotomy Prone or Ventral Decubitus Position Lateral Decubitus Sitting
Place person in “natural” position
If possible, allow person to assume the position prior to receiving anesthesia.
Supine Position
Dorsal decubitus
Most common operative position
Position preferred by anesthesia providers access to airway access to arms for IV’s/monitors
hemodynamic reserve is maintained
Arm Boards in Supine
Properly secured to OR table Abducted < 90 degrees, avoids stretch brachial plexus Padded Safety straps Hands- supinated (palm up) NOT pronated
Arms Tucked in Supine
Draw sheet under pt. hip or torso, NOT mattress; elbow padded; palm in
Supine Feet and lumbar Support
-Feet heels not hanging over bed heels padded legs not crossed -Lumbar support slight flexion hips and knees pillow under knees (caution-DVTs) elastic compression stockings and SCD/ sequential compression devices- increase venous return/ decrease risk DVT ***Safety strap***
Supine Position-Complications
Brachial Plexus Injury:
Avoid abduction >90 degrees- produces caudal pressure in the axilla from the head of the humerus
Avoid direct compression at neck Shoulder pads should be avoided
Ulnar: hands and forearms supinated, or
kept in a neutral position w palms toward body, proper padding at elbow
Name other complicatons of Supine Position
Pressure alopecia
Backache
PNIs
Aortacaval syndrome- compression of the abdominal aorta and inferior vena cava by the gravid uterus when a pregnant woman lies on there back.
Lawn chair position
Good for MAC or General. Legs elevated takes pressure off the lower back
Trendelenburg
Tilting a supine pt head down. Reasons: CV and respiratory consequences: venous return FRC pulmonary compliance
Trendelenberg: Cerebral Blood Flow
Increases intracranial vascular congestion-
GRAVITY!!! INCREASED INTRACRANIAL PRESSURE—
which decreases cerebral blood flow
Intraocular pressure increases.
Who would NOT be a good candidate for this position?
Steep Trendelenburg
- -Steep (30-45 degrees) commonly used: robotic/gyn surgeries
- -Once robotic instruments are connected, OR table should not be moved.
Anesthetic Concerns
Cephalad slide How do we prevent? Options: anti-skid pads (gel, egg crate) flexion of knees shoulder braces Strap
Trendelenberg shoulder braces
Use EXTREME caution with shoulder braces! - if they must be used they should be well padded and placed laterally away from the root of the neck over the arcomioclaviular joint
Trendelenburg Anesthetic Concerns
swelling of the face, tongue (macroglossia), and/or larynx
extubation concerns?
stomach above the glottis—airway?
migration of ETT?
Displacement of abdominal contents
Reverse Trendelenburg
“Head up”
often facilitates upper abd sx (shifts abd contents caudad)
Variations of this position may be used for shoulder, neck, intracranial surgery.
This is a variation of the sitting position in terms of physiologic changes.
Reverse Trendelenburg Concerns
caudal slipping
venous return?
Decreases
What happens when the supine (flat) position is resumed? Temporary increase
In the reverse Trendelenburg position, what happens to cerebral perfusion pressure?
Decreases
Lithotomy position
Common: GYN, rectal, and urology
Hips flexed 80—100 degrees
Legs abducted 30-45 degrees from midline
Knees are flexed until lower legs are parallel with torso
Recommendation: legs should be periodically lowered if the sx extends beyond 2-3 hours!
Lithotomy FYI
If herniated disc, positioning might need to be assumed prior to anesthesia.
Pt is usually asked to ”move down” to the foot of the bed.
Intubation difficulties?
Lithotomy Anesthetic Considerations
Raising and lowering legs require a COORDINATED effort.
Lift and position legs simultaneously
Possible nerve injuries in Lithotomy
Improper positioning may lead to the following nerve injuries: femoral, sciatic, obturator, lateral femoral cutaneous, saphenous, common peroneal*.
Lithotomy Position- Candy Can Stirrups
Usually more acute flexion of the knees and/or hips
Watch injury to common peroneal nerve, femoral, sciatic
Lithotomy Position Knee-Crutch Style
Watch popliteal nerve (tibial nerve and common peroneal nerve
Lithotomy Anesthetic Considerations
Requires careful positioning! careful padding of extremities watch fingers and hands major CRUSH injuries Recommended position armboards If arms MUST be tucked, personally visualize fingers/hands prior to raising leg section
Lithotomy Anesthetic Considerations for CV and Respiratory
CV consequences legs elevated inc venous return increases transient increase in CO Respiratory consequences cephalad displacement of abd contents Decrease lung compliance Decrease tidal volume Decrease peak pressures
Lithotomy Anesthetic Considerations for PNI
PNI common peroneal nerve. Compression of the nerve. between the lateral head of the fibula and the candy-cane bar sciatic obturator lateral femoral cutaneous Compartment syndrome—think perfusion
Lithotomy Position Risk Factors
Risk factors
low BMI.. bony areas
smokers
prolonged duration of sx
Lateral Decubitus Position
Common: thorax (thoracotomy)
retroperitoneal (kidney) hip
Lateral Decubitus Anesthetic Considerations
Careful positioning! (Miller, p. 1249)
Requires cooperation of ENTIRE team
Lateral Decubitus Anesthetic complications
Focused attention to:
head (neutral position)-additional pillows
arms abducted <900
dependent ear
dependent eye- Tape eye before mask ventilating.
ALWAYS check pulse in dep arm
Indication(s) of vascular compression? 5 P’s
pulse, pulse ox wave form
NIBP differences?Higher in dependent arm.
Lateral Decubitus Anesthetic and Axillary Roll
Purpose: ensures weight of the thorax is borne by chest wall and to avoid compression on axillary neurovascular structures.
ALWAYS check pulse in dep arm
b/t chest wall and the bed just caudal to the dependent axilla (never IN the axilla to prevent injury to the brachial plexus and axillary artery)
Lateral Decubitus Anesthetic Considerations
Padding of bony prominences nondependent/dependent arms Knees (downside knee is bent) Padding of knees Common peroneal & saphenous nerve Restraining straps
Lateral Decubitus Pulmonary Consequences
Pulmonary consequences
Mechanically ventilated, paralyzed patient
The dep lung is compressed by the weight of the mediastinum and cephalad pressure of abdominal contents
Therefore ventilation is better which lung?
Perfusion is better in which lung?
Lateral Decubitus V/Q mismatch
V/Q Mismatch
Awake and spontaneous breathing
Dependent (lower) lung is both better perfused and better ventilated, but lung volumes (FRC, VC, TV decrease)
Anesthetized but spontaneous breathing
Nondependent lung better ventilated and dependent lung is better perfused (V/Q mismatch)
Anesthetized, mechanically ventilated patient
Nondependent lung is overventilated and dependent lung is overperfused (worse V/Q mismatch)
V/Q Mismath
All situations have more perfusion to the dependent lower lung
Awake & spontaneously breathing—the dependent lung receives more ventilation because
contraction of dependent hemidiaphramis more efficent compared to the nondependent upper hemidiaphragm
Dependent lung is more favorable part of the compliance curve ( natural elastic recoil of the lungs opposes shift of abdominal organs.
Anesthetized but spontaneous breathing-
Decease in FRC with anesthesia moves the nondependent upper lung to a more favorable part of the compliance curve, but moves the dependent lower lung to a less favorable position. As a result, the nondependent upper lung is ventilated more than the dependent lower lung; V/Q mismatching occurs
Anesthetized and positive-pressure ventilation—positive pressure ventilation favors the nondependent upper lung because it is more compliant than the lower lung. Neuromuscular blockade enhances this effect by allowing the abdominal contents to rise up further against the dependent hemidiaphragm and impede ventilation of the lower lung. Further worsens V/Q mismatch
Decreased volume of dependent lung; increased perfusion of dependent lung. Increased ventilation of dependent lung in awake patients (no V/Q mismatch); decreased ventilation of dependent lung in anesthetized patients V/Q mismatch. Further decreases in dependent lung ventilation with paralysis and an open chest (Morgan, 4th ed)
In the anesthetized patient who is in the lateral position, abdominal contents shift cephalad, moving the hemidiaphragm of the dependent lung upward, thereby decreasing ventilation in the dependent lung and reducing its compliance. In the nondependent lung ventilation is greater and compliance increased because the caudal shift of the upper hemidiaghragm allows unrestricted lung excursion. (Nagelhout, 4th ed p 436-7)
Ventilation decreased to dependent lung due to pressure on lung from abdominal viscera
Barash, 8th ed. (2017) p.
Basics of Anesthesia, 7th ed. (2018), p. 325
Lateral Position:Cerebral Blood Flow
Minimal change unless there is extreme flexion of the head.
Prone Position
Ventral decubitus Concerns
Thoracic outlet syndrome- pressure on the arteries and veins and nerves in your upper chest, causes pain coldness and numbness.
Assess by asking pt to lift and clasp arm.
Prone Position
Ventral decubitus
Common: posterior fossa, post spine, perirectum, and lower extremities
Intubation of the trachea, IV access, esophageal temp probe, oral airway, foley, etc occurs on the stretcher.
Eye care—tape, lubricant, goggles
Secure ETT very WELL
Who is responsible for coordinating the move and repositioning the head?
CRNA
Prone Position Safety
Monitored Anesthesia (MAC) or General Anesthesia (GA): Flex and pad the legs
Face: facedown or turned to side
Arms: tucked @ sides or pos above above head (“Superman”)
Prone Position Safety
Arms
Elbows
Compression hose
Remember, arms < 900, especially if head is turned—prevention of brachial plexus injury
Padding of the elbow prevents Ulnar
Usually compression hose to minimize venous pooling
Moving to pt to the prone position.
Move from stretcher to OR table is a coordinated event
Who is responsible for coordinating the move and repositioning the head?
Disconnection vs disconnection of lines
After the move, immediately reapply monitors
CHECK ETT position (how?)
Bilateral breath sounds
Check head (neutral or side lying) P
Patient dependent
caution: stroke, carotid stenosis, spine issues
Mayfield Head Tongs/ Pins
Watch for bolt slippage
Want natural neck alignment
Eyes, nose, chin free of pressure/ metal components touching
Prone Position and the face complications:
check and recheck face visual loss... Ischemic optic neuropathy CAUSES: intraoperative hypotension anemia Inc. crystalloid use large blood loss long duration of surgery Head down leading to increase IOP
Prone Position and ABD pressure
check abd—avoid compression
Abd pressure impedes venous return by compressing IVC, thus decreasing CO
External pressure elevates intraabd & intrathoracic pressures
Significance?
Try to avoid high pressures to prevent bleeding.
Sends out pressure to the epidural veins which causes bleeding
Prone and Respiratory consequences
Respiratory consequences
Ext pressure on abd dec FRC, pulm compliance, and inc peak airway press
Use bilateral firm rolls or bolsters
Clavicle to iliac crests
Check breasts and male genitalia
Prone Position: Cardiovascular Changes
IVC and Aortic Compression- hypotension
Venous pooling in lower extremities- hypotension
Leads to decreased preload, C.O. and BP
Hypotension associated with the move to prone position must be anticipated, monitored and treated as necessary.
Prolonged hypotension in addition to pressure on the face/eyes may lead to blindness!!
Prone Position:Cerebral Blood Flow
Turning head obstructs venous drainage leading to increased cerebral volume and ICP.
Excess flexion or turning - obstruction of vertebral artery flow.
Spinal cord injury from stretch
How do we prevent abd wall pressure?
Firm rolls or bolsters
Clavicle to iliac crest
Wilson frame
Jackson frame
All serve to decrease abdominal compression by the OR table and maintain normal pulmonary compliance
Prone Position Concerning populations
Concerning populations
morbidly obese
resp compromised
repositioning difficulty
Sitting position surgx. advantages and disadvantages
sx adv: posterior cervical spine and post fossa
excellent surgical exposure
dec blood in operative field
reduced perioperative blood loss
sx disadv: venous and paradoxical air embolism
Sitting Position Anesthesia advantages
Anesthesia advantages
superior access to airway
reduced facial swelling
improved ventilation
Sitting Position Anesthesia advantages
Anesthesia advantages
superior access to airway
reduced facial swelling
improved ventilation
Sitting Position Anesthesia concerns
head may be pinned or taped
arms need supporting to the point of slight elevation of the shoulders
knees slightly flexed to reduce stretching on sciatic nerve
feet supported and padded
Sitting Position Drastic Hemodynamic Effects
Pooling of blood leads to hypotension incremental positioning IVFs, vasopressors adjustment of anesthetic depth leg compression devices maintain venous return (VR)
Sitting position –Head and neck position
Head and neck position
Hyperextension cervical cord injuries
Flexion impedance of blood flow
hypoperfusion or venous congestion of brain
impedance of breathing blockage of ETT
pressure on the tongue
mid-cervical tetraplegia
Rule of Thumb: maintain @ least 2 FBs distance b/t the mandible and the sternum
Beach Chair: Variation of Sitting Position
Common: shoulder surgery
Surgical adv: superior access to shoulder when compared with lat dec. position
Better mobility/manipulation of joint
Beach Chair position anesthesia concern
Significant Neuro & CV alterations: Pooling--- decreased venous return Reduced CPP Reduced preload, CO, BP! Hypotension (deliberate or permissive) loss of compensatory mech a/w anesthesia Failure to compensate for height of head
CPP and Sitting Position
Conversion Factor: 1 cm rise = 0.77 mmhg drop in MAP in the head
If MAP is 65 mmhg in the head it is 50mmhg in the head.
Sitting Position: Ventilatory Changes
Lung volumes and capacities increase
Lung compliance increases
Work of breathing easier
Mechanical ventilation and spontaneous ventilation easier in this position
Venous Air Embolism (VAE)
Elevation of the surgical field above the heart and open dural sinus (creation of pressure gradient between the atmosphere and the veins) might cause VAE
Sitting Position:Venous Air Embolism (VAE)
VAE is a risk ANY TIME the surgical site is above the level of the heart !!!
Inability of venous sinuses to collapse
It is a potentially LETHAL complication!
Signs of VAE include: change in heart tones (wind mill murmur) heard via doppler placed at the parasternal border (2nd-6th IC space), new murmur, dysrhythmias, hypotension, desaturation, DECREASED EtCO2, Nitrogen in exhaled gas, circulatory compromise, and cardiac arrest
Detection of entrained air with TEE or precordial Doppler ultrasound
Sitting Position:Venous Air Embolism (VAE) Treatment
Treatment
Flood surgical field with NS, apply wax to cut bony edges, close any open vessels
D/C nitrous oxide
Place on 100% O2, PEEP
T-berg position
Aspirate air from right atrium via a catheter
Sitting Anesthetic considerations
Monitor BP in reference to the level of brain
Avoid and rapidly treat hypotension or bradycardia
Careful positioning of head to prevent occlusion of cerebral vessels
Monitoring of CPP, if available
Brachial Plexus
The Risk:
The nerve travels a long superficial course through fixed points
*cervical vertebrae
*axillary fascia
Brachial Plexus Injury
Positioning injury occurs with
neck extension, head turned to side, or sagging sideways
excessive abduction of arm > 90 degrees
arm/ arm board falls off table
depressed sagging shoulders (prone/sitting)
extending arms overhead (prone)
compression plexus against thorax (lateral)
shoulder braces
sternal retractors in cardiac surgery
Deficit if injured:
limp or paralyzed arm
lack of muscle control in arm, hand, wrist
lack of sensation in arm or hand
Ulnar Nerve Injury
Inability to abduct or oppose 5th finger
Loss of grip strength, esp. ulnar side of fist
Loss sensation palmar surface of hand, 4th or 5th fingers
Eventually, leads to atrophy of intrinsic muscle of hand (claw hand)
Radial Nerve
Injury due to external compression of the radial nerve on the lateral aspect of the humerus against
IV Poles
surgical retractors
ether screen
mismatched arm board
repeat BP inflation
Deficit is injured:
loss of extension of forearm, weakness of supination, and loss of extension of hand (wrist drop) + fingers
loss of sensation in lateral arm, posterior forearm, part of hand
Ulnar Nerve
Nerve runs in groove between olecranon of ulna and medial epicondyle of humerus
Injury with:
compression of nerve between the olecranon of ulna & medial epicondyle of humerus (entrapment with arm extension)
stretch with severe elbow flexion
dislocation over medial epicondyle with pronation hand causing stretching
compression against bed
misplaced BP cuff
Common Peroneal Nerve Injury cause and symptoms
Most frequently damaged nerve of lower extremity
Branch of sciatic
Injury from
Compression of lateral aspect of knee against stirrup or lateral position
Symptoms
foot drop, inability to evert the foot, loss of dorsal extension of toes
Sciatic Nerve Injury
Sciatic nerve injury
excessive external rotation hips; hyperextension of knee
pressure in sciatic notch from stretching
Sciatic injury – weakness or paralysis of muscles below knee; numbness foot & lateral half of calf; foot drop
Femoral Nerve Injury
Injured with compression at pelvic brim by retractor or excessive angulation of thigh/ abduction of thighs and external rotation of hips
Results in loss of flexion hip and loss of extension of knee; decreased sensation over superior aspect thigh
Saphenous Nerve Injury
Saphenous nerve injury
Occurs when medial aspect of lower leg compressed against support bar
Results in paresthesias medial and antermedial side of calf
Lower Extremity Compartment Syndrome
Occurs when perfusion to an extremity is inadequate, resulting in ischemia, edema, and extensive rhabdomyolysis from increased tissue pressure
Occurs with long surgical procedures (> 2-3 hours)
Occurs with lithotomy and lateral decubitus positions
Treatment is fasciotomy
