190624_Positioning Flashcards
PNIs
22% of claims, 2nd only to deaths
Mechanisms of injury: stretching, compression, and ischemia
Pt positioning is always suspected
The position for surgery is largely DICTATED and ACCEPTED or MODIFIED by
the surgion
Primary role for the CRNA/MDA:
protect the airway and vascular access
promote physiologic homeostasis
all while the pt is in the required position.
Ulner neuropathy
in part, unknown
anethesia stress….virus
immunosuppression
Most common PNIs
Spinal cord
Bracial Plexis
Ulner nerve
Purpose of Operative Positioning
Surgical Exposure and/or Surgical Access
Comfort
Patient Safet #1
Bed max weight
only over central column
Most Common Operative Positions
Supine or Dorsal Decubitus Position – Trendelenburg – Reverse Trendelenburg Lithotomy Prone or Ventral Decubitus Position Lateral Decubitus Sitting
Supine Position
Dorsal decubitus
hemodynamic reserve is maintained
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***
Arms Abducted < 90 degrees, avoids stretch brachial plexus
- Hands- supinated (palm up) NOT pronated or
- Draw sheet under pt. hip or torso, NOT mattress; palm in
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 pos w/ palms toward body,
proper padding at elbow
Pressure alopecia Backache PNIs Aortacaval compression syndrome Sit to supine = temp ^BP & CO
Variations of the Supine Position
Lawn chair position:
Good for MAC or General
Legs elevated takes pressure off the lower back
Commonly for pt awake procedures
Trendelenburg
Reasons: HTN, Central Line
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?
- obesity, glocoma, ICP (ex. tumor), cards complications
Steep Trendelenburg
steep (30-45 degrees) we dont like, but we do a lot commonly used: robotic/gyn surgeries Once robotic instruments are connected, OR table should not be moved. Arms tucked!!!
Anesthetic Concerns: cephalad slide ~ PNI How do we prevent? - anti-skid, padding - padding - flexion of knees
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 complications
swelling of the face, tongue (macroglossia), and/or larynx
– extubation concerns?
stomach above the glottis—airway?
migration of ETT?
CV and respiratory consequences: – venous return = increase = work load increase - temp BP increase – Fnctional Residual Capacity = decrease - Vt = decrease – pulmonary compliance = decrease?
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 complications
Anesthetic Concerns
caudal slipping
venous return? decreased
What happens when the supine (flat) position is resumed? Temp increase in BP & Work load
In the reverse Trendelenburg position, what happens to cerebral perfusion pressure? Decreased
Lithotomy position
Common: GYN, rectal, and urology
Hips flexed 80—100 degrees
Legs abducted 30-45 deg from midline
Knees are flexed until lower legs are parallel with torso
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? YES
Raising and lowering legs require a COORDINATED effort = same time same direction
Recommendation: legs should be periodically lowered if the sx extends beyond 2-3 hours!
Risk factors
– low BMI
– smokers
– prolonged duration of sx
Lithotomy complications
Improper positioning may lead to the following nerve injuries: femoral, sciatic, obturator, lateral femoral cutaneous, saphenous, common peroneal*.
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
PNI – common peroneal n. • Compression of the n. between the lateral head of the fibula and the candy-cane bar – sciatic – obturator – lateral femoral cutaneous
Compartment syndrome—think perfusion
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 CV & Resp complications
CV consequences • legs elevated > increase venous return • increases transient inc in CO Respiratory consequences • cephalad displacement of abd contents • decreased lung compliance • decreased tidal volume • increased peak pressures
Lateral Decubitus Position
Common: thorax (thoracotomy) retroperitoneal (kidney) hip
Careful positioning! (Miller, p. 1249)
• Requires cooperation of ENTIRE team
Focused attention to:
– head (neutral pos)-additional pillows
– arms abducted <90deg
– dependent ear
– dependent eye
Speaking of eyes, when do you tape?
- after prop and before masking
NIBP differences? Dep Arm > Non-Dep Arm
Padding of bony prominences – nondependent/dependent arms – Knees (downside knee is bent) – Padding of knees • Common peroneal & saphenous n – Restraining straps
Lateral Decubitus Position - Axillary roll
Axillary roll (I do not agree w name) – b/t chest wall and the bed just caudal to the dependent axilla (never IN the axilla)
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
Indication(s) of vascular compression?
- 5Ps
- Pulse Ox = decreased wave form
Lateral Decubitus Position-Pulmonary consequences
– Mechanically ventilated, paralyzed pt
The dep lung is compressed by the weight of the mediastinum and cephalad pressure of abd contents
Therefore ventilation is better which lung?
Non-dep lung
Perfusion is better in which lung?
Dep-lung ~ gravity
- V/Q = 0.8
Unanesthetized Anesthetized
V Q V Q Non-dep Lung down down up down Dep-Lung up up down up
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)
READ NOTES!!!!! Slide 59
Lateral Position: Cerebral Blood Flow
Minimal change unless there is extreme flexion of the head.
Prone Position
Ventral decubitus
Thoracic Outlet Syndrome~similar to bracial plexus injury - wave arms and extend behond hea, if pain, then hands need to be placed at side!
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 STRECHER!
Eye care—tape, lubricant, goggles
Secure ETT very WELL
Who is responsible for coordinating the move and repositioning the head? WE ARE!!!!
MAC or GA: Flex and pad the legs
Face: facedown or turned to side
Arms: tucked @ sides or pos above above head (“Superman”)
Remember, arms < 90deg, especially if head is turned—prevention of brachial plexus injury
Padding of the elbow prevents PNT
Usually compression hose to minimize venous pooling
Moving into Prone Position
Move from stretcher to OR table is a coordinated event
Who is responsible for coordinating the move and repositioning the head? WE ARE!
Disconnection vs disconnection of lines? WTF do whats safe!
After the move, immediately reapply monitors
CHECK ETT position (how?)~listen
Check head (neutral or side lying)~PMH
Prone Position - Anesthetic Concerns
Mirror systems?
Horseshoe adapter?
Mayfield rigid pins (cranial or cervical spine surgeries)
check and recheck face
visual loss
ischemic optic neuropathy
– intraoperative hypotension
– anemia
– Inc. crystalloid use
– large blood loss
– long duration of surgery
– Head down leading to inc IOP
check abd
—avoid compression
– Abd pressure impedes venous return by compressing IVC, thus decreasing CO
– External pressure
elevates intraabd & intrathoracic pressures
– Significance? INCREASED VENOUS PRESSURES = INCREAESED bleeding
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
Mayfield Head Tongs/ Pins
Watch for bolt slippage
Want natural neck alignment
Eyes, nose, chin free of pressure/ metal components touching
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
Prone Position: dec abd compression
Firm rolls or bolsters
– Clavicle to iliac crest
Wilson frame
Jackson frame
All serve to dec abd compression by the OR table and maintain normal pulm com’
Female breast: free of compression and positioned medial to gel bolsters
Male genitalia: free of pressure
Prone Position: Concerning populations
morbidly obese
resp compromised
repositioning difficulty
Sitting position
sx adv: post cerv 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
– superior access to airway
– reduced facial swelling
– improved ventilation
Sitting Position-Anesthetic 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
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
Sitting Position-Anesthetic Concerns-HEMODYNAMIC EFFECTS
DRASTIC HEMODYNAMIC EFFECTS Pooling of blood = hypotension • incremental positioning • IVFs, vasopressors • adjustment of anesthetic depth • leg compression devices = maintain VR
Sitting Position-Anesthetic Concerns-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
• midcervical 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: Variation of Sitting Position-neuro & CV alterations
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
**delta = 0.77mmHg/cm, 1mmHg/com, 2mmHg/2.5com
***CPP = 35 = flatline EEG, = 20 = irreverable damage
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
Sitting 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
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!
Detection of entrained air with TEE or precordial Doppler ultrasound
Signs of VAE
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
Sitting Position: Venous Air Embolism (VAE) 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
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
Brachial Plexus: Deficit if injured
– limp or paralyzed arm
– lack of muscle control in arm, hand, wrist
– lack of sensation in arm or hand
Ulnar Nerve
Nerve runs in groove between olecranon of ulna and medial epicondyle of humerus
Ulnar Nerve injury
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
Ulnar Nerve Deficit if injured
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)
Common Peroneal Nerve Injury
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
Symptoms
– weakness or paralysis of muscles below knee; numbness of 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
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
PNI Worksheet??????????????
= Test questions WTF is this work sheet??????
