Positioning Flashcards
Possible complications include
Peripheral nerve injuries
Hypotension
Ventilatory compromise
Optic neuropathy
Physical injuries associated with positioning: such as
skin damage, fractures and amputation.
Can contribute to post-op complications.
Obesity Diabetes Arthritis Peripheral vascular disease, Alcohol abuse pre-existing neurological conditions
Most common surgical positions
Supine Trendelenburg Prone Lateral Decubitus LITHOTOMY Sitting
This position produces minimal circulatory effects
The supine (lying down)
FRC with supine
decreased by about 800 ml
The decrease in FRC with supine position reflect
Cephalad displacement of the diaphragm compressing the lung bases
What conditions can further decrease the FRC
This is further exacerbated by an enlarged abdomen such as with obesity, pregnancy, or ascites.
The hips and knees in supine position
are often flexed slightly with a pillow under the knees,
Hips and knees flexed in supine Facilitating
venous drainage from the lower extremities and decreasing anterior abdominal wall tension.
Heels and occiput should be
padded
For pregnant patient remember
put a wedge under the right hip of the pregnant patient in the supine position
What does the LEFT LATERAL DISPLACEMENT do
Keeps the gravid uterus from causing too much pressure on the inferior vena cava that decreases venous return to the heart further resulting to decrease in cardiac output.
If the arms can be abducted on a padded board it
must be no more than
90 degrees
Take care that there is no pressure on the
ulnar nerve at the elbow in the condylar groove.
The arms are often secured in a “papoose”
manner with a draw sheet. This effectively limits
the
anesthetist’s access to the arms.
Supine summary
Equalization of pressures throughout the arterial system;
increased right-sided filling and cardiac output
decreased heart rate and peripheral vascular resistance (PVR).
Gravity and lungs
Increases perfusion of dependent (posterior) lung segments; abdominal viscera displace diaphragm cephalad.
SV favors
dependent lung segments,
CV favors
independent (anterior) segments.
FRC decreases and may
fall below CV in older patients.
________the patient in supine position with a
head-down tilt
Trendelenburg
Trendelenburg abdominal viscera action ? can accentuate HyPOTENSION
The abdominal viscera push on the diaphragm, compressing lung bases and heart (↓SV). this can accentuate HYPOTENSION
Cardiac output also decreases in this position d/t
stimulation of baroreceptors
Trendelenburg
Cardiac output decreases in this position TRENDELEBURG
Stimulation of baroceptors
Trendelenburg ____ICP how?
In some patients, this position can increase intracranial
pressure by elevating venous pressure
_________can also be caused by decreased venous
return
Hypotension
NO longer use _____braces why?
Shoulder braces are no longer used routinely due
to possible brachial plexus injury caused by the
compression of the plexus against bony
structures of the shoulder
If shoulder braces are used they should be well
padded
If shoulder braces used positioned so they are over the not the ______or ______
acromion, the clavicle or base of the neck
CV of Trendelenburg
Activation of baroreceptors, generally causing
decreased cardiac output, peripheral vascular resistance, HR and BP.
Respiratory effects of Trendelenburg: lung capacities _______from ?
Marked decreases in lung capacities from shift of
abdominal viscera;
Respiratory effects of Trendelenburg: VQ
Increased V/Q mismatching and Respiratory atelectasis; increased likelihood of regurgitation.
Trendelenburg: NEURO
Increased ICP and decrease in CBF because of cerebral Neuro venous congestion
Trendelenburg: EYE
Increased IOP in patients with glaucoma.
Reverse Trendelenburg: Cardiac
Preload, CO, arterial pressure
preload, cardiac output and arterial pressure decrease.
Reverse Trendelenburg Baroreflexes i
Increase sympathetic tone, HR and PVR.
Reverse Trendelenburg: SV and FRC
SV requires less work; FRC increased.
Reverse Trendelenburg: NEURO
Decreased CPP and CBF
PRONE position do not
*DO NOT TUG, PULL, PUSH, HELP
Main Objective for PRONE Is
Maintain alignment of the head, neck and spinal cord with neck slightly flexed.
In prone The diaphragm is displaced _______there is
impediment of _______________
cephalad, downward descent of the diaphragm,
Prone Peak airway pressures______ and pulmonary
compliance_____
increase ; decreases
In prone, pressure on the-____and _______ lung bases
forced. This can be offset by________, which may further
inferior vena cava and aorta; cephalad
mechanical ventilation; compromise blood flow
Bolsters (“jelly rolls”)
can be placed under the patient from iliac crests to shoulders;
When using these techniques (frames) the arms can be placed ________or on_______ palongside the
patient’s head taking care to avoid pressure on the______
at the sides, ; added boards; ulnar nerves at the elbows
Be aware that prolonged time in the prone position and large fluid loads can cause_______. Evaluated______
cause swelling of the upper airway and tongue. Evaluate the face before you extubate.
Ischemic optic neuropathy, a rare but potentially
devastating complication can occur with the
prone position
What is Ischemic optic neuropathy?
An infarction of the optic nerve due to decreased
oxygen delivery by one or more small arterioles supplying the nerve
Potential causes of ION
Potential causes include: long operating times
(average 7 hours or more), large blood loss, relative
hypotension and anemia
Prone position and ION
The prone position may elevate CVP and retard the
drainage through opthalmic veins
Risk factors for ION
Patient risk factors include hypertension, diabetes, CAD,
and smoking
ION can be partial or cause complete blindness and is
not reversible
Summary PRONE CV
Pooling of blood in extremities and compression of abdominal muscles may decrease preload, cardiac output and BP.
SUMMARY Resp PRONE
Compression of abdomen and thorax decreases total lung
compliance and increases work of breathing.
Summary Neuro effects prone
Extreme head rotation may decrease cerebral venous drainage and CBF.
This position is most often used for hip, kidney, and
thoracic procedures
Lateral Decubitus
In lateral decubitus
The inferior vena cava can be compressed by the kidney
bar under the dependent iliac crest compromising blood
flow
During mechanical ventilation, the dependent lung is
relatively_______ due to compression by the
underventilated ; weight of the mediastinum and abdominal contents
IN lateral decubitus The nondependent lung is relatively______because its compliance is______
overventilated ;increased
Gravity causes pulmonary bloodflow to favor the
dependent lung
Should not pose problems with venous return
Lateral decubitus
In lateral decubitus This mismatching of Ventilation and Perfusion (V/Q mismatch) can lead
to hypoxemia
*****To avoid compression of the neurovascular bundle in the dependent axilla
*****axilla, an “axillary roll” is placed just caudad
to the axilla
Axillary roll placement in the axilla may displace the ____________against __________ causing nerve injury from stretch and compression
head of the humerus; brachial plexus
Placing the pulse oximeter on the ______ _______and periodically checking the _______of the dependent arm ensures there is
dependent hand; radial pulse; no neurovascular compromise
The upper arm can rest on pillows or be placed in a padded support bar (Allen arm rest) taking care not
to stretch the brachial plexus
Position the patient’s head on a pillow, preferably an
anesthesia___________ with or without extra blankets to keep the_________
“donut”, or shea headrest ; neck in normal
alignment
A pillow is placed between the knees, and the lower
leg should be to________ pad bony
prominences and lessen stretch on nerves
flexed slightly
Genitals must be free of
pressure
Lateral Decubitus: CV
Cardiac output remains unchanged unless venous return
obstructed (e.g. kidney rest). Arterial BP may fall as a result
of decreased vascular resistance (right side > left side).
Resp LATERAL DECUBITUS
Decreased volume of dependent lung; increased perfusion of dependent lung. Increased V of dependent lung in awake patients (no V/Q mismatch); decreased V of dependent lung in anesthetized patients (V/Q mismatch). Further decreases in dependent lung ventilation with paralysis and open chest.
Sitting position Most often used for
shoulder surgeries and posterior fossa craniotomies
Sitting May cause gravity _____
dependent hypotension
Causes venous drainage from head and neck
Supine
Decreases intrathoracic blood volume
Supine
No pulmonary changes with this position
Supine
Venous return from the lower extremities is enhanced by the use of
compression stockings and pumps
↓ cerebral perfusion pressure and cardiac output
SItting
What happens when the surgical site is higher than the heart, there is potential to entrain room air into open vessels and cause venous air embolism
When the surgical site is higher than the heart, there is
potential to entrain room air into open vessels and cause
venous air embolism
Air enters the right ventricle interfering with blood flow into the pulmonary artery
Pulmonary edema and reflex bronchconstriction can occur
Death can result from acute cardiovascular collapse and
arterial hypoxemia
Air may reach the cerebral and coronary circulation via a
patent foramen ovale (present in approximately 20% to 30% of the population)
VAE is treated by
Telling the surgeon so he can
prevent the further entraining of air by irrigating and applying an occlusive dressing
In sitting, Placing the patient in a head down position (to
trap the air in the right atrial apex preventing entrance to the pulmonary artery)
Withdrawing air through a previously placed right atrial
catheter
Cardiovascular collapse will need treatment with pressors
_______is the most sensitive noninvasive indicator of VAE
Placement of a doppler ultrasound transducer at the
second or third intercostal space to the right of the
sternum (over the right atrium)
Most definitive test VAE
Most definitive is still with the TEE
Sudden decrease in end-tidal CO2 indicates
decreased perfusion to the lungs
Sitting SUMMARY CV
• Pooling blood in lower body decreases central blood volume.
Cardiac output and arterial BP fall despite rise in HR and SVR.
Sitting summary Respiratory
Lung volumes and FRC increase, work of breathing increases.
SItting summary
CBF decreases
places the supine patient’s legs in abduction with hips and knees flexed and supported in separate holding devices
referred to as “stirrups
Lithotomy position
Used for gynecological and lower GI procedures
Lithotomy position
In the lithotomy, circulation can be
Circulation can be disrupted by increased pressure on the inferior vena cava especially in the presence of obesity, an abdominal mass, or pregnancy
The diaphragm is displaced
cephalad by the abdominal viscera, compressing lung bases
Lithotomy May aggravate______
back problems.
Lithotomy, the legs should be raised and lowered in unison to prevent
rotary stretch on the lumbar spine
When the patient has been placed in the stirrups, the
bottom part of the table (foot) is
lowered to provide access to the patient
IN lithotomy position; always be aware of
ALWAYS BE AWARE OF WHERE THE PATIENT’S
HANDS ARE WHEN RAISING AND LOWERING
THE END OF THE OR TABLE
T/F Finger damage and even amputations have resulted from crush injuries with fingers caught between the sections of the OR table
True
The biggest hazard of the lithotomy position
Injury to peripheral nerves (sciatic, common peroneal,
femoral, saphenous and obturator) i
To prevent nerve injury in lithotomy
Proper padding between the patient’s legs and the
stirrups is essential
A rare complication of lithotomy is_______ due to decreased perfusion and pressure on
compartment syndrome; the lower extremities
This results in tissue necrosis and rhabdomyolysis
Compartment syndrome with lithotomy
In lithotomy autotransfusion from leg vessels _____ Effect
increases circulating blood volume and preload;lowering legs has opposite effect.
BP and CO in lithotomy position
BP and cardiac output depends on volume status.
Decreases vital capacity; increases likelihood of aspiration
Lithotomy
Causes of peripheral nerve injuries
Position related compression or stretching of nerves
Cubital tunnel entrapment
Type of surgery
Prolonged placement (usually more than 4 hours) in the
lithotomy position
Prolonged application of a tourniquet (usually more than 2
hours)
Hereditary neuropathy or congenital anomalies
Pre-existing diseases for cause peripheral nerve injuries
(DM, Vit. Deficiency, Alcoholism, Ca, Cigarette Smoking, PVD, etc).
*****The most common peripheral nerve injury
Ulnar nerve injury
The two major sites of injury are
the elbow at the condylar groove AND
the cubital tunnel
The condylar groove is formed by the medial epicondyle of the humerus and the olecranon process
of the ulna. The ulnar nerve is shallow at this points
pre-disposing to
compression injury, especially in males where there is less protective adipose tissue
The cubital tunnel is formed by the________________ also
aponeurosis of the flexor capri ulnaris, designated the cubital tunnel retinaculum
Injury to the ulnar nerve causes the inability to__________or _________
abduct or oppose the fifth finger,
Injury to the ulnar nerve, there is diminished sensation over both surfaces of the
forth finger and 1/2 fifth finger, and eventually, atrophy of the intrinsic muscles of the handknown as “claw hand” or “Pope Sign”.
The second most common postoperative nerve injury
Brachial Plexus injury
An axillary roll placed too proximal can compress
the head of the humerus against the brachial plexus
Shoulder braces can compress the
brachial plexus between the clavicle and the first rib
Radial nerve injury manifested as a
Injury is manifested by wrist drop, inability to
extend the metacarpophalageal joints, & weakness
of abduction of the thumb.
_____ not likely to be injured from positioning.
The median nerve
Axillary: other injury
inability to abduct arm
Musculocutaneous
inability to flex forearm
Stretching is most likely to occur in___
lithotomy position
To minimize sciatic nerve stretch, it is recommended patients in lithotomy position be positioned with ________external rotation, hips and knees should be______, and duration be limited ideally to
minimal ;flexed; less than 4 hours
Injury can manifest as “foot drop” and may be
erroneously diagnosed as
peroneal nerve injury
The most frequently damaged nerve in the lower
extremities
Common Peroneal Nerve
______And _____can show the extent of the injury
Nerve conduction velocity and electromyography studies
T/ F If the electromyogram is performed promptly, it can
show if there was neuropathy pre-op because signs of
denervation resulting from acute injury do not appear
until 18 to 21 days after the event and are limited to a
specific nerve distribution
True
Limit arm abduction to
90 degrees or less
In lateral position, use a correctly placed
axillary roll
Ulnar Nerve
Avoid ____________
Limit flexion of the elbow to less than ____degrees
Avoid compression on the condylar groove
Limit flexion of the elbow to less than 110 degrees
Radial Nerve
Avoid pressure against
posterior and lateral humerus
Median Nerve
Avoid ______
Avoid extreme wrist dorsiflexion
Be aware of caustic infusions in the antecubital fossa
A tourniquet is used on an arm or a leg to provide the
surgeon with a bloodless field, and is inflated to at least
50mmHg higher than the patient’s systolic BP
3 are recorded on the anesthesia record
The time of inflation, deflation, and the tourniquet
pressure
Typically the anesthetist notifies the surgeon at
one hour,
ninety minutes and two hours
Ischemic nerve damage can occur after _______of
tourniquet time. Typically the surgeon will let the
tourniquet down for ______after two hours and reinflate if needed.
two hours ; 15 minutes
External pressure on the eyes can cause thrombosis of
the
central retinal artery
- Venous Air Embolism. Common in sitting, prone,
and reverse T positions. Prevention:
•**
•
maintain venous pressure above 0 at the wound.
- Backache: All positions.
Lumbar support, padding and slight hip flexion.
Compartment syndrome: esp. Lithotomy. ***.
Maintain perfusion pressures and avoid external
compressions
- Alopecia: Common in supine, lithotomy and T
positions. *
Normotension, padding and occasional head turning.
- Corneal Abrasion. Esp. Prone. **
- Taping and/or lubricating eye.
- Digital Amputation: All positions. ***
Check for protruding digist before changing table
position/configuration
- Nerve palsies
• a. Brachial plexus. All positions. **
Avoid stretching or direct compression of neck or axilla
• c. Radial. All positions. ***
Avoid compression of lateral humorous.
• d. Ulnar. All positions. ***
Padding at elbow, forearm supination.
- Retinal ischemia. Prone and sitting. ***
Avoid pressure on the globe.
- Skin necrosis. All positions.
Padding over bony prominences
Common peroneal. Lithotomy & lateral
decubitus. *
Pad lateral aspect of upper fibula.
“axillary roll” is placed
just caudad to the axilla
