Positioning for Surgery Flashcards
What is the most commonly injured nerve in the operative patient?
Ulnar nerve
What percentage of anesthetic claims are related to nerve injury?
15-16%
What AANA standard addresses liability of patient positioning during a surgical case?
Standard V
What specific portion of Standard V addresses assessment and protective measures related to positioning?
Subsection F
What term is used to define an act that speaks for itself in the court of law?
Res Ipsa Loquitur
What are the goals of proper positioning of the patient?
Patient Safety
Adequate operative exposure without exceeding anatomical and physiological limits
Adequate respiratory excursion and ventilation
Normal vital signs
No ischemia or compression
What are the three major physiologic areas of concern related to positioning?
Cardiovascular
Pulmonary
Nerve Injuries
What specific cardiac issues concern us regarding anesthesia and patient positioning?
Impaired autonomic nervous system
Depressed CO
Redistribution of circulating volume (gravity)
Compression of extremities or great vessels
What specific pulmonary issues concern us regarding anesthesia and patient positioning?
Positive pressure ventilation (decreased FRC & compliance)
Barriers to thoracic excursion
Loss of HPV
What are the two types of ischemia of the nerve sheath?
Direct: compression of the nerve
Indirect: Compartment syndrome
What specific neurological issues concern us regarding anesthesia and patient positioning?
Ischemia of the nerve sheath
Patient is unconscious (can’t tell us if something is wrong)
Reduction in skeletal muscle tone (easily stretched)
Focal pressure can exceed capillary perfusion pressure
How should the patient be moved and positioned?
Slow, physiologic, coordinated and smooth movement
What is the anesthetists role in positioning the patient?
Ensure adequate circulation Support the head Protect the airway Good anatomical alignment of all body parts Assess the patient
What four pathological mechanisms lead to nerve injury?
Stretch
Compression
Generalized ischemia
Metabolic derangement
What patient factors are associate with an increase risk for nerve injury?
DM
Tobacco use
HTN
What are the four basic surgical positions?
Supine
Prone
Lateral
Lithotomy
Define the patient’s position in the supine position?
Patient is face-up on the OR table, lying on their back and the arms are secured next to the patients body
What position should the forearms be in if the patient is supine?
FA should be supinated
What angle of the arms should not be exceeded in the supine position?
< 90 degrees
What can occur if the forearms are pronated in the supine position?
Ulnar nerve compression at the cubital tunnel at the elbow
What can be avoided by keeping the arms <90 degrees in the supine position?
Brachial plexus stretch
How should the arms be positioned if the patients arms have to be tucked in the supine position?
The elbows should be kept off the edge of the table to avoid ulnar nerve injury
The hands should be parallel to the trunk
How does the supine position impact the pulmonary system?
Total lung capacity and functional residual capacity are reduced (GA takes away abdominal tone and allows the viscera to impede on the diaphragm and compresses the lungs)
How does the supine position impact the cardiovascular system?
Blood pressure is uniform throughout
Compensatory mechanisms from AN to change venous return are attenuated by anesthesia
What part of induction is different when the prone position is required?
GA is induced on the stretcher
How are the arms typically positioned in the prone position?
Arms usually fully adducted or abducted and flexed at the elbow, avoiding pressure to the axilla
Why do we support the body at the chest in the prone position?
It allows the abdomen to hang free which cuts down on bleeding in spine surgeries
What pressure points should be padded in the prone position?
The elbows, knees, ankles and genitalia
What is a complication associated with the prone position?
Postoperative vision loss
What is the number one cause of postoperative vision loss?
Ischemic optic neuropathy (INO) 89%
What is another cause for postoperative vision loss?
Central retinal artery occlusion (CRAO)
What are some prevention strategies for postoperative vision loss?
Surgical duration 70)
Maintain Hct >25%
What cardiovascular changes are seen in the prone position?
Lower extremity/gut pooling of blood
Inferior Vena Cava compression (affecting preload)
Epidural engorgement
What pulmonary changes are seen in the prone position?
Compliance may be decreased if the chest is not free
May actually be an increase in FRC (better ventilation of the posterior lung may actually increase oxygenation)
How should the head be positioned in the lateral position?
Head neutral and supported on a pillow or doughnut head holder
What body parts should be aligned in the same plane in the lateral position?
Shoulders, hips head and legs
How should the arms be positioned in the lateral position and what kind of support should be provided?
The dependent arm should be placed on a padded arm board perpendicular to the torso
Axillary support should be placed under the dependent side of the thorax
Non dependent arms should be placed parallel to the dependent arm
What cardiovascular changes are seen in the lateral position?
Changes usually minimal unless hypovolemic
What pulmonary changes are seen in the lateral position?
V/Q mismatching can occur
Dependent lung lower than left atrium and prone to atelectasis and fluid accumulation
FRC is increased in the nondependent lung and decreased in the dependent lung
How does utilizing a kidney rest in the lateral position affect the patient’s cardiovascular status?
Compression of abdominal great vessels can decrease venous return
Why is it important to move both legs together when placing a patient in the lithotomy position?
To avoid strain on the pelvic ligaments or hip dislocation
How should the arms be positioned in the lithotomy position?
Arms tucked or abducted <90 degrees with precautions as with a supine case
What is important to protect when removing the bottom half of the bed for a patient being placed in the lithotomy position?
Avoid finger injury if they are hanging over the edge of the table, can get pinched
What two factors contribute to lumbosacral plexus injuries when a patient is in the lithotomy position?
Acute abduction and external rotation of the hips
What can lead to popliteal vein obstruction if the patient is in the lithotomy position?
Extreme flexion of the knees
What nerve injury that occurs in the lithotomy position can cause foot drop?
Peroneal nerve injury
What factor can lead to compartment syndrome in the lithotomy position?
If the legs are above the level of the heart, poor perfusion to the lower extremities
What cardiovascular changes are seen in the lithotomy position?
Central blood volume auto-transfusion of 600mL when legs are raised (be aware in patients with CHF)
What pulmonary changes are seen in the lithotomy position?
FRC reduced by 20% due to abdominal shift
Vital capacity decreased
Hypoventilation can occur in spontaneously breathing patients
How can large amount of auto transfusion be avoided in when placing a patient in the lithotomy position?
Raise the legs slowly but ALWAYS together
Describe the sitting position.
HOB 30-90 degrees about horizontal plane
The operating table is flexed and the backrest is elevated
How is the head secured in the sitting position?
Holding device, sometimes flexed but maintain at least two finger breaths between neck and mandible (take the pressure off of C5)
What are we preventing by flexing the legs at the knee in the sitting position?
Sciatic stretch
How should the patient’s arms be positioned in the sitting position?
Secure arms on the padded armboards or secure on patients lap using a drawsheet
What is the anesthetist most concerned about when the patient is in the sitting position?
Movement of the ETT, make sure the patient’s face, chin and ETT are aligned properly
What three complications are associated with the sitting position?
Quadriplegia
Pneumocephalus
Venous Air Embolism
How does VAE occur from the patient in the sitting position?
Negative pressure gradient between the R atrium and the veins at the operative site (sucks air in)
What precaution can be made to prevent paralysis in the patient in the sitting position?
Two finger breaths between the chin and chest to limit strain at the C5 vertebra
What is a pneumocephalus?
Entrainment of air into the head or brain itself
Why does pneumocephalus occur when a patient is in the sitting position?
Opening of the dura, drainage of CSF and surgical decompression allow the entrainment of air
What cardiovascular changes are seen in the sitting position?
Impaired venous return and reduced SV leads to decreased CO (up to 20%)
Massive venous pooling in lower extremities
Cerebral perfusion decreased
What pulmonary changes are seen in the sitting position/
FRC increases with increased compliance
