Lecture 2: Positioning Flashcards
Name 3 purposes of operative positioning.
- Comfort
- Patient safety
- Surgical Exposure/Access
What types of information should be documented regarding positioning?
- Baseline range of motion
- the intra-op position
- Use of padding
- Frame
- Body position
- Checks done and frequency
Newer OR tables have what weight limit?
270kg or 600lbs
Which position is the most common? Why do we like it?
Supine. Because we have access to the airway, hands and feet a lot more this way. Less physiologic changes than in other positions
A pillow is placed under the head in supine position for what two main reasons.
Allow for proper sniffing position
Avoids dorsal extension and lateral flexion of neck.
What is the process to tucking a patient’s arms?
Draw sheet is under the patients hip or torso (not the mattress) elbow is padded and the palms are into the side of the leg.
Name an advantage and a disadvantage to tucking arms in?
Surgeon can stand really close. We lose access to them (if we need to start another IV, or if something becomes disconnected we can’t see them)
How far is it appropriate to abduct arms secured to armboards? What happens if we go too far? What could happen if the straps were too tight? What could happen if the arms were pronated on accident?
Under 90 degrees. Brachial Plexus injuries. Compression. Ulnar nerve entrapment.
Hands should be?
SUPINATED
In the supine position we don’t want anything too hard or too high under the knees because?
We don’t want to obstruct venous blood flow.
It is/is not acceptable for heels to lay over the bed?
Is not
Name the 5 mechanisms for nerve injuries.
- Stretching
- Compression
- Kinking
- Ischemia
- Transection
Microvascular _______ is probably a cause in every nerve injury.
Ischemia
Name some factors that contribute to nerve injuries.
How we position them, prolonged surgery, technique we use, GA because the patient can’t move themselves, having preexisting diseases like DM, CVD and obesity
What are the two fixed points through which the brachial plexus courses?
Vertebral foramina fascia and the axilla.
When does brachial plexus injury occur? What normally causes it?
Neck extension Head turned to the side Arm board extended/abducted more than 90 degrees Arm/armboard falls off the table. Retractors Humerous pressed into chect Stretching.
Name four things that could cause a radial nerve compression injury.
- Surgical retractors
- Ether screen
- Mismatched arm board (it has a step off that digs into the back of the arm)
- Repeated BP inflation
What kinds of manifestations would a patient with a radial nerve injury present with?
wrist drop
weakness in abduction of the thumb
numbess 1, 2 and right fingers
How can we injure the ulnar nerve?
in cubital tunnel at the elbow groove compression of the nerve between the olecranon of ulna and the medial epicondyle of humerus (entrapment with arm extension). Also by stretch with severe elbow flexion, dislocation with pronation hand, nerve dislocation over medial epicondyle with stretching, compression against the bed.
What patient population is more likely to suffer a ulnar nerve injury?
Muscular men.
Describe the claw hand.
Inability to abduct or oppose 5th finger.
Weak grip ulnar side of fist.
Loss of sensation palmar surface 4th and 5th fingers.
Atrophy of intrinsic muscles of the hand.
How do we reduce the risk of ulnar nerve injury? (6)
- Pad arm boards
- Avoid downward compression by strap.
- Assure surgical personnel do not compress patient’s arm
- Place BP cuff proximally so that it does not impose on ulnar groove or cubital tunnel
- Avoid prolonged flexion of the elbow
- Avoid excessive abduction/extension.
Supine position has what kind of effects on circulation and perfusion?
Minimal
Name four ways to improve venous return from the lower extremities.
- Uncross legs
- Pad heels
- Pillow beneath knees
- Flexed hips and knees.
What can cause IVC compression in the supine position?
masses, pregnancy, obese abdomen and ascities.
Upward displacement of the diaphragm and compression of the lung bases in the supine position cause what kind of a change in FRC? What further reduces lung volumes?
+ or - 800ml.
Muscle relaxants
Muscle relaxants do what to chest wall muscle? What does this due to elastic recoil? How do we overcome this?
We lose chest wall muscle
Reduces opposition to inherent elastic recoil
Overcome with positive pressure ventilation.
Do we see a change in cerebral blood flow in the supine position?
Minimal due to tight autoregulation
What do we use trendelenberg for? What does it improve, help with and facilitate?
Used to treat hypotension by increasing venous return
Improves surgical exposure during abdominal and laparoscopic surgery (takes abdominal contents out of the pelvis)
Helps prevent air embolism
Facilitates cannulation during CL placement
Tell me about the cardiovascular changes in T-berg (4).
- Used to counteract hypotension- controversial and short term only increases VR to the heart up to 1L into the central circulation.
- Causes reduced blood flow to the LE
- May cause compression of the heart by abdominal contents pushing cephalad
- Baroreceptors are activated- PV dilation and bradycardia may make “shock syndromes” worse in the long run.
What happens when the supine position is resumed from T-berg?
They could become more hypotensive especially if they are hypovolemic to begin with.
What are the ventilatory changes associated with T-berg?
- Contents of the abdomen are pushed upwards impeding diaphragmatic excursion, compresses the lung bases, decreases lung compliance, decreases FRC and PIP increases. ETT could be shifted into R mainstem as everything shifts up.
What are the risks associated with T-berg?
Aspiration and face and airway edema can lead to airway obstruction. Look for periorbital, lip and tongue edema.
What kind of changes do we see in cerebral blood flow with T-berg? (3). Who would not be a good candidate for this?
Increased intracrainal vascular congestion due to gravity.
Increased ICP.
Increased IOP
Neuro patients in which increased ICP is a problem. Severe glaucoma.
Why and when do we use Reverse T-berg? What is it a variation of in terms of physiologic changes?
Use it to enhance surgical exposure of the upper abdomen by shifting the abdominal contents caudad. Variations may be used for shoulder, neck, breast, ENT and intracranial surgery. Variation of sitting position in terms of physiologic changes.
What do we need to worry about in regards to patient positioning with reverse T-berg?
Patients can slide. We may want a footboard. Worry about hyperextension. Would want to relieve that pressure every now and again. Could cause anterior tibial nerve injury which would result in foot drop.
Name four cardiovascular changes associated with Reverse T-berg. Name something we can do to monitor cerebral perfusion pressure?
Reduced preload, CO (20-40%) and BP
Compensatory increased SNS, SVR and HR plus or minus 30%. (be careful it could be blunted by anesthetics give lower dose and fluid bolus)
Activation of RAAS
Venous pooling in the lower extremities (use compression stockings)
Move the transducer of the aline to the circle of willis.