Positiong Part II Flashcards
What is the prone positioning used for?
Used for surgical access to posterior skull, posterior spine, buttocks, perirectal area, lower extremities.
What are the characteristics of prone position?
- Torso supported on a frame or with rolls that extend from the shoulders to the iliac crest
- supports placed crosswise at the pelvis and shoulders
- Lower legs are supported with pillows
- Upper extremities tucked at sides or supported on armboards with the arms flexed at the shoulders and elbows
- Breasts and genitalia must be positioned to limit pressure
What needs to be assessed prior to prone position?
- Assess preoperative range of motion
- Head, neck, shoulder, and arm mobility
- Arm placement may be limited by ankyloses of shoulder or elbow joints
What is the patient transfer components to the prone position?
- Patient anesthetized on the gurney
- Log-rolled onto the bed, frame, or rolls with good body alignment maintained
- Planning of monitor placement
- Remove monitors or have them remain in situ
- Disconnected from the breathing circuit to avoid accidental extubation
What is anesthetisa’s role in the prone position transfer?
–Control airway
–Control head and neck
–Coordinate turn
What needs to be checked when in/moving to the prone position?
- Keep neck inline with spine
- Make sure you have enough extension on all lines/circuit
- Reassess immediately after the move for endotracheal tube position and adequate ventilation
What are the CVP effects in the prone position?
Positioning devices that allow abdomen to hang freely associated with greater decreases in inferior vena cava pressures than those that compress the abdomen
What are the LV volume effects in the prone position?
Reduced secondary to decreased venous return and increased intrathoracic pressure
What are the CI effects in the prone position?
May be decreased or unchanged in prone position compared with the supine
What are the V/Q effects in the prone position?
- More lung volume is present posteriorly then anteriorly
- Anterior mediastinal structures occupy significant space
- Posterior lung segments are better ventilated
- Ventilation is more uniform and ventilation-perfusion matching is better in the prone position (compared with supine position)
What are the changes in elastance and resistance of diaphragm and abdomenin the prone position?
- Diaphragmatic excursion can be limited by abdominal viscera if the abdomen is compressed by the weight of the body or positioning devices
- If abdomen hangs free gravity allows the abdominal contents to shift reducing interference with diaphragmatic movement
What are the effects of lung capacity in the prone position?
Increase in FRC when the abdomen hangs free
What causes swelling in the head?
Prone and Trendelenburg positions may increase venous pressure in the head with resultant swelling of facial, pharyngeal, and orbital structures
What can cause increased ICP?
Intracranial pressure can be elevated when the head is dependent b/c venous pressure is transmitted to the head and intracranial structures through the valveless jugular systems
What can cause decreased CBF ?
CBF can be decreased when inflow is limited by venous congestion in intracranial structures
What effect can Prone position have on the eyes?
Postoperative visual loss (POVL) may result from an increase in ocular venous pressures and concomitant decrease in ocular perfusion pressure
What can occur in the prone and head down position?
Facial edema, macroglossia, and airway edema may occur following prone and head-down positions
What can prevent facial edema?
10-degree head-up tilt may prevent development of facial edema
Describe the different prone positions in this picture
- A – Classic prone position with torso supported on chest rolls
- B – Jackknife prone position
- C – Prone knee to chest position
What occurs in the A prone variation position?
A - Prone position with Wilson frame
Arms abducted <90 degrees; pressure points padded; chest and abdomen supported away from the bed to minimize abdominal pressure and preserve pulmonary compliance; foam head pillow has cutouts for eyes and nose and a slot to permit the ETT to exit; eyes checked frequently
What occurs in the B prone variation position?
B - Mirror system
Bony structures of head and face supported; monitoring of eyes and airway facilitated with a mirror
What occurs in the C prone variation position?
C - Prone position with horseshoe adapter
Head height adjusted to position neck in neutral position
What occurs in the D prone variation position?
D - Prone position with horseshoe adapter as seen from below
- Horseshoe adapter permits access to airway and visualization of eyes
- Width may be adjusted to ensure proper support by facial bones
What needs to be done to the head in prone position?
Head in neutral position. If lateral rotation may compromise carotid or vertebral arterial blood flow or jugular venous drainage.
Mayfield pinning= _____________
NO movement
What can happen to the abdominal in the prone position?
- Pressure can force the diaphragm cephalad & impair ventilation
- If intra-abdominal pressures approach or exceed venous pressure, return of blood from the pelvis and lower extremities is reduced or obstructed
- Increased difficulty with hemostasis
_________ abdominal pressure!
Remove
Where should the trunk be placed in the prone position?
Elevate trunk off supporting surface (free ventral abdominal wall)
What can the SCDs do in the prone position?
SCD minimizes pooling of blood and supports venous return
What can T-berg occur in the prone position?
T-berg: venous and lymphatic stasis in the head (facial & airway edema)
Ischemic optic neuropathy = __________
vision loss
Where should the breast be placed in the prone positioning?
Breast placed medial to the bolsters
How should the arms be in the prone position?
“Surrender Position”/ “Superman Position”:
Extended ventrally at the shoulder, flexed at the elbow, abducted onto arm boards
What does the superman position prevent?
No tension at shoulders
What should happen to the ulnar n. and the pulses in the prone positioning?
- Ulnar n. @ elbows should be padded
- Pulses @ wrist should be full
What is the andrew’s frame?
What is the Wilson’s frame?
What cam cause a brachial plexus in the prone injury?
- Arms abducted more than 90 degrees
- Abduct arms minimally
- Inadequate support of shoulders allows them to sag anteriorly causing traction on the plexus
- Extending the arms over the head may compress the plexus between the clavicle and first rib
What happens to ocular venous pressure during surgery?
- Head-down tilt
- Increased abdominal and right atrial pressure
- Obstruction of jugular venous return
Where should the head be placed in the prone position to avoid visual loss?
Head should be placed in neutral position (avoid excessive flexion) and level with or slightly elevated above the heart (10-degree head-up tilt)
What preventative devices can be used to help prevent vision loss in the prone positioning?
■Horseshoe adapter least preferred head support technique because of pressure on the eye and risk for POVL
■Foam head pillows w/ cutouts are preferred
What patients are at high risk of POVL?
length procedure in the prone or steep Trendelenburg position, esp. if surgery is accompanied by significant blood loss
What is associated with prone position?
–Hemiparesis and quadriplegia (spinal cord injury) are associated with prone positions
What is not present in the intervertebral veins that can cause issues in the prone positioning?
–Valves are not present in the intervertebral veins that drain the vertebral and spinal cord venous plexuses into the lumbar veins
Where is external abdominal pressure is transmitted to?
–External abdominal pressure is transmitted to the vena cava and communicated to the lumbar epidural veins
What can engorged epidural veins cause?
- Engorged epidural veins are fragile and easily traumatized
- Ensuing blood loss will decrease surgical exposure and contribute to hypotension
What are airway complications can occur in the prone injury?
- ETT
- Edema
What is the ETT components that can occur in the prone position?
- Displaced, kinked, or disconnected when patient is moved for position change
- Right main stem intubation may occur as a result of flexion of the neck
What is the edema components that can occur in the prone position?
- Extensive edema of the face, tongue, and oropharyngeal structures
- Gravitational forces or increases in hydrostatic pressure may restrict venous return from the head and neck
What are the extubation considerations in the prone position?
- Macroglossia or upper airway edema may necessitate leaving the patient intubated after surgery until edema subsides
- Verify an air leak around the ETT or examine larynx via direct laryngoscopy before extubation in suspected patients
What can prevent corneal abrasions? What can cause corneal abrasions?
- Three-point skull fixation*, horseshoe headrest, and foam cushions allow head to be placed in a neutral position while the eyes are kept free of pressure
- Head may slip or rotate on horseshoe headrest allowing pressure to be applied over the globe and placing the patient at risk of central retinal artery thrombosis
What artery can be effected by the corneal abrasions?
central retinal artery thrombosis
What are pressure point locations in the prone position?
–Pad pressure points at elbows, knees, and ankles
–ECG leads
–Nose, eyes, face
What are protective steps for the eyes and ears?
■Closed eyelids
■Eyes protected
■Lubricate eyes +/-
■Head at level with or higher than heart
Avoid intra-abdominal pressure to __________________
decrease venous congestion
Review the parts of the prone postion protection,
What is another name for the sitting position?
“Semi-reclining”/ “Beach chair”
What is the basics of the sitting position?
■Legs elevated to level of heart
■Head flexed
What needs to be used in the sitting position?
- SCDs
What are the main advantages of the sitting position?
access to airway, reduced facial swelling, improved ventilation
What are the advantages of sitting position?
- Decreased blood loss
- Better surgical exposure
- Access to ETT, chest, extremities
- Decrease facial swelling
- Decrease intracranial pressure
What are potential issues to the sitting position?
- Circulatory instability
- Cranial nerve dysfunction
- Impaired venous drainage
- Air embolus
- Peripheral nerve injury
- Postop central apnea
- Quadraplegia
- Pneumocephalus
What are the components of the Sitting Position – Beach Chair?
- Flexion of the operating room table to 45 degrees
- Head positioned in a brace (North-star, Mayfield, etc.)
- Elevation of the backrest and legs
- Non-surgical arm is often secured on the patient’s lap between two pillows
- Pad heels, ankles and elbows
What are the components of the operating table in the Sitting Position – Beach Chair?
Flexion of the operating room table to 45 degrees
- Degree of torso elevation desired determines amount of operating table manipulation required
What are the components of the head position in the Sitting Position – Beach Chair?
Head positioned in a brace (North-star, Mayfield, etc.)
- Head down rotation
What is the component of the non-surgical arm in the Sitting Position – Beach Chair?
Non-surgical arm is often secured on the patient’s lap between two pillows
- Ensure elbow is padded to prevent damage to ulnar nerve
- This position makes the non-surgical arm a difficult option for the peripheral nerve stimulator
How is the head secured in the sitting position?
The patient’s head is secured using a horse-shoe or North-star headpiece,
What is the north star head-piece?
Northstar - Tightens on the sides of the head and has a strap across the forehead
What are the characteristics of the North star headpiece?
- Leave at least 2 finger breadths between chin and sternum
- Watch ears to ensure necrosis or pressure does not occur
- Monitor strap on forehead to prevent pressure necrosis
- Consider where to place peripheral nerve stimulator
What is a consideration in the north star headpiece?
- Consider where to place peripheral nerve stimulator
- Face may be risk, but hand will be covered, and feet are less accurate
What is a risk in the north star headpiece? What can this cause?
Monitor strap on forehead to prevent pressure necrosis
- Ensure this does not migrate into the eyes
- Potential for abrasion or pressure injury
Identify this device.
Mayfield Head Rest
What is a property of the Beach Chair Position?
Decreasing in popularity by neurosurgeons
What is a great characteristic of the Beach Chair Position?
Risk of VAE
What is the use of Beach Chair Position?
- Used for posterior fossa and cervical spine procedures
- Used during some breast surgeries
- Shoulder arthroplasty and arthroscopy
What does Beach Chair Position allow for?
- Allows visualization of intracranial structures
- Facilitates drainage of blood and cerebral spinal fluid from the wound
What is the effect of Beach chair position on the brachial plexus?
Sitting position reduces brachial plexus stretch and aids surgical exposure and manipulation of the arm and shoulder
What are the characteristics of nervie injury in the beach chair position?
- Vigorous surgical manipulation of arm and shoulder can move the patient’s body toward the operative side of the table
- Surgeries >4hr increase risk of nerve injury
- Hyperflexion of hips, abduction and extension of legs in sitting position can lead to sciatic nerve injury
If the head is firmly secured to the headrest, excessive traction or stretch can be placed on the _________
neck and brachial plexus
How can a sciatic nerve injury be prevented?
Flex table at the knees
What are common injuries in the beach chair position?
- If restraining straps are loose head can become partially or completely dislodged from the head rest
- Pressure injury to face and/or ears
- Injuries from surgeon placing instruments on the patient’s lap
What are the characteristics of spine injury from the beach chair position?
Cervical spine injury, especially with extreme flexion of the head (traction on the cord) but also with extension with pre-existing cervical issues (spondylolithiasis, arthritis, etc.)
What can happen if sufficient quantities of air are entrained?
Arrhythmia, desaturation, pulmonary hypertension, circulatory compromise or cardiac arrest
What is a life threating injury with the Beach Chair Position?
Venous air embolism
When can Venous air embolism occur?
Can occur in any position where a negative pressure gradient exists between the right atrium and the veins at the operative site
What effects the severity of Venous air embolism?
Severity based on volume of air entrained and rate of entrainment
What effect does air have on the vasculature system? What does this produce?
- Air that enters the right side of the heart can limit gas exchange in the lungs as it displaces blood in the pulmonary vasculature
- Air in the pulmonary vessels can result in an increase in PAP and hypoxia
What is the capnography with Venous air embolism?
Monitoring capnography will reveal a drop in end-tidal CO2 and the presence of end-tidal nitrogen
What murmur is present with Venous air embolism? Where is this heard?
- A “mill-wheel murmur” is a characteristic of VAE that can be heard through the esophageal or precordial stethoscope or precordial doppler (most sensitive noninvasive)
- Placed over 3rd to 6th intercostal spaces to the right of the sternum
What is the gold standard for detecting a Venous air embolism?
TEE gold standard for sensitivity – Detects <0.2ml/kg
Air in the coronary arteries can cause ___________ changes
ischemic electrocardiographic
Review diagnosis of venous air embolism.
What is the proper position of precordial doppler?
Review the normal capnography waveform and the changes associated with Venous Air Embolism.
What is a risk factor for VAE?
Paradoxical air embolism (PAE) can occur in the patient with PFO/ASD
What is a paradoxical air emobolism?
- Paradoxical air embolism (PAE) can occur in the patient with PFO/ASD
- Air can enter systemic circulation when right atrial pressure is greater than left atrial pressure (reversal of the normal pressure gradient)
What can small amounts of air in the arterial system result in?
Small amounts of air in the arterial system can result in severe cardiovascular and neurologic complications
What is preoperative screening for PFO/ASD involve?
TEE or transcranial doppler
How can air be removed from circulation?
- Entrained air emboli may be removed from the circulation by aspiration through a multiorifice central venous catheter
Where is the catheter placed for removal of air emboli in the sitting position?
For patients in the sitting position the catheter is placed in the right atrium at the junction of the superior vena cava
What is the risk with central venous catheter placement?
The risks of central venous catheter placement, the potential for VAE, and the cardiopulmonary risks of the position must be weighed against the benefits of fluid volume management and air recovery with a CVP catheter
What is the first step for the treatment of VAE?
Notify surgeon and flood surgical field with saline and wax bone edges
What needs to be stopped when a patient has VAE?
D/C nitrous oxide; administer 100% oxygen
What can be preformed to treat VAE? What does this cause?
- Perform Valsalva maneuver or compression of jugular veins
- Increases cerebral venous pressure and induces bleeding
What can be used to aspirate VAE?
Aspirate air from atrial catheter
What can be used to support BP with VAE?
Support BP with volume and vasopressors
How should a patient with a VAE be positioned?
Reposition patient in left lateral decubitus with a 15 degree head down tilt if BP continues to decrease
What may need to be modified with VAE?
Modify anesthetic as needed to optimize hemodynamics
What is the postoperative follow up for VAE?
Postoperative follow up should include ECG, CXR, ABG
What is another Beach Chair Position - Life Threatening Injuries?
Pneumocephalus
Frequent occurrence after neurosurgical procedures performed in the sitting or supine position
Pneumocephalus is typically a ______ condition
benign
What is the most important factor for the development of pneumocephalus?
Gravity is the most important factor in the development of pneumocephalus
What are the characteristics of pneumocephalus?
Opening of the dura, drainage of cerebrospinal fluid, and surgical decompression allow relaxation of the brain and entrance of air, which rises to the top of the cranial vault
What are contributing factors to Pneumocephalus?
Contributing factors are those that decrease brain volume:
- Use of diuretics
- Hypocarbia
- Presence of intraventricular shunts
- Gross hydrocephalus
What is the principle property of Tension pneumocephalus?
Rarely occurs
What is the manifestation of Tension pneumocephalus?
- Onset manifests as restlessness, deterioration of consciousness, convulsions, or other changes in neurologic status
Tension pneumocephalus= Requires ___________ to prevent rapid deterioration
Immediate intervention
What is the definitive diagnosis for Tension pneumocephalus?
Definitive diagnosis made by the presence of air on CT
What is the treatment for Tension pneumocephalus?
Must drain via twist drill holes
What must be avoided with Tension pneumocephalus?
Avoid nitrous oxide
What is a rare but devasting compolication of Beach Chair Position?
Quadriplegia
How does Quadriplegia occur with the beach chair position?
Results from cervical spine ischemia with neck and head hyperflexion
Who is at high risk for quadriplegia?
Elderly patients with cervical spine deformities and vascular pathologies have higher risk
How can quadraplegia be prevented?
During positioning sufficient distance between chin and neck (at least 2 finger-breadth) is recommended to avoid neck hyperflexion
____________ may occur if endotracheal tube is secured by a supporting device and the head is displaced
Accidental extubation
What can neck flexion cause?
- Lead to right mainstem intubation
- Impede arterial and venous blood flow
- Kink the ETT
- Put significant pressure on the tongue
What is the Bezold – Jarisch Reflex (sitting position)?
Profound hypotension and bradycardia from activation of Bezold-Jarisch reflex may occur when surgery is performed in sitting position with an interscalene block
What is the treatment of Bezold – Jarisch Reflex?
Atropine
How is hypotension a product of sitting position?
- Patient is intubated supine position then head is placed in holder and raised
- As you head raises the BP is likely to drop
- CO and BP reduce
What are intervention for intial hypotension to head raise?
Raise the head halfway, cycle a BP, treat if necessary, and then raise to final position
What are characteristics of CO and BP reduction from the sitting position?
- CI, CVP, and PCWP decrease significantly and SVR increases (compared with supine position)
- Take BP on non-operative arm and consider BP in brain may be 15-20mmHg lower than cuff pressure
- May consider Ted-hose or other mechanisms to reduce venous pooling
What is true about BP in the brain when a patient is in sitting position?
Take BP on non-operative arm and consider BP in brain may be 15-20mmHg lower than cuff pressure
What can be given to treat hypotension?
Consider increasing intravascular volume if indicated
What is a concern in the sitting position? What are interventions to prevent/monitor this?
Cerebral perfusion may be a concern
- Invasive arterial blood pressure monitoring may be instituted with the transducer placed at the level of the circle of Willis (tragus)
- Hypotension should be avoided
What are the favorable positions for ventilation?
- Less effect on lung volumes than other positions
- Torso is elevated so smaller effect on lung mechanics
- Forced vital capacity and FRC remain within normal parameters
Review conversion factor for beach chair.
Define components of postural hypotension.
- reduction of SBP.
- Measure MAP @ Circle of Willis (measures CPP)
Define components of air embolus.
- air migrates to the heart.
- Prevents effective ventricular contraction
- Increases with degree of elevation above the heart
Define components of facial edema.
- 2/2 venous & lymphatic obstruction.
- Avoid chin to chest.
Define midcervical tetraplegia.
- after Hyperflexion of neck with or without rotation of head
- causes paralysis below the general level of the fifth cervical vertebra.
Define components of sciatic nerve injury.
stretch injury with flexed hips w/o bending knees (foot drop)
What is the indication for Trendelenburg Position?
Urology, gynecology, robotics
What is a nerve injury associated with Steep Trendelenberg?
Brachial Plexus
What are causes of Brachial Plexus injury?
- Brachial plexus (stretch if shoulder pads peripheral; compression if too medial)
- Possible radial and ulnar injury
What is the prevention for Brachial Plexus?
- Place shoulder brace over acromioclavicular joint to prevent brachial plexus injury
- Pad pressure points
- Make sure palms face the legs and are by the sides
What is a technique for supine injury prevention?
Shoulder Braces
Wht are common injuries of Steep Trendelenberg?
- Corneal abrasions
- Increased intraoptic pressure
- Shoulder displacement
- Increased risk of sliding off table
- Peripheral neuropathy (DM, PVD, etc.)
- Oral ulcerations
What are life threatening concerns with Steep Trendelenberg?
- Excessive pharyngeal and laryngeal edema
- Increased ICP/cerebral edema
- Ischemic optic neuropathy associated blindness
- Aspiration
What may need to be done for a patient in steep trendelenburg?
Excessive pharyngeal and laryngeal edema
- Pt may need to remain intubated post op to allow time for airway edema to resolve
- Check for ETT cuff leak
What are the prevention for Steep Trendelenberg?
–Use of straps, gel pads, etc.
–Cautious of duration of surgery
–Limited volume administration
–Taping of eyes
–Aspiration pneumonitis prophylaxis
–SpO2 monitoring of peripheral extremities/digits
What is the treatment if aspiration is suspected?
If aspiration is suspected, treatment with broad spectrum abx, keep patient intubated.
What is the anesthetic considerations for steep trendelenberg?
- Decrease in FRC and total lung capacity
- Increase in central venous pressure
- Reflex bradycardia secondary to baroreceptor reflex activation > vasodilation > hypotension
What are the components of increase CVP in steep trendelenberg?
–Reliability of CVP monitoring may not be accurate
–Reliability of volume status may not be accurate (hypotensive when return to dorsal decubitus
Diaphragm displacement more ______ in steep trendelenberg.
Cephalad
