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29 Cards in this Set
- Front
- Back
Goals of Positioning
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Maximum exposure to the surgical area while preventing injury
Access to the patient for assessment, maintenance of ventilation, infusion of drugs, and appropriate monitoring. Patient achieves satisfactory surgical outcome without injury |
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Causes of Position Related Injury
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Pressure applied over body surface for period of time
Nerve damage from compression, traction, stretch, angulation, or kinking |
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Position-Related Factors
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Positioning Devices
Length of Procedure Anesthetic Technique Surgical Procedures |
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Positioning Devices
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Straps used to restrain patient
Lateral femoral cutaneous nerve Crutch or “Candy-Cane” stirrups Common peroneal nerve Shoulder braces w/ steep Trendelenberg (head down) Brachial Plexus injury Blood Pressure cuff/tourniquet Radial nerve Improperly placed axillary roll Compartment syndrome |
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Length of Procedure
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Surgery longer than 4-5 hours is usually associated with higher incidence of nerve injuries.
Nerve injury that occurs in short cases is usually due to stretch, compression, or traction |
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Anesthetic Technique
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Nerve injury occurs more commonly with general anesthesia
Patient cannot move in response to painful stimuli Paralytics increase mobility of joints |
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Surgical Procedures
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Cardiac procedures with median sternotomy
Ulnar and brachial plexus injuries Vaginal hysterectomy Femoral and lumbar plexus injuries |
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Supine
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Head neutral on small pillow (doughnut)
Avoid brachial plexus injury Pt. legs uncrossed without pillow! Avoid superficial peroneal nerve damage Arms padded, less that 90 degrees, supinated. Avoid ulnar nerve damage |
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Supine cont.
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Cardiac output and BP transiently increase
General anesthesia attenuates normal baroreceptor response FRC and TLC reduced/cephalad shift of diaphragm |
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Prone- face down
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Supine for induction and intubation
Optimal exposure for spinal or back surgery Reduces incidence of VAE when used with posterior fossa surgery Body is supported with chest frames (or rolls), leg pillows, upper extremities secured to armboard Pad all pressure points at elbow, knee, ankles, genitalia(man), limit pressure on breasts. |
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Prone cont.
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Anesthetist responsible for maintaining head alignment during turn
Protect patient eyes – blindness can occur if central retinal artery is occluded. Foam cushion, pillow, 3 point skull fixation, Mayfield headrest, etc Arms should be carefully rotated into position. |
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Hemodynamic changes in Prone
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Cardiac output is decreased in prone position.
Other hemodynamic variables do not change significantly. Avoid pressure over abdomen that impedes venous return |
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Prone- Ventilation is affected by?
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limited anterior chest expansion
Diaphragmatic excursion can be limited by the abdominal viscera FRC decreased (?) compared to sitting position, but not as much as supine pt Oxygenation improved despite decrease in FRC |
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Prone Complications
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Eye injury – corneal abrasion, visual loss
Macroglossia – seen with extreme flexion head, do not use oral airway! Neurologic injuries – brachial plexus VAE, not as common as sitting position |
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Lithotomy
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Used for surgery requiring access to perineal structure.
Arms are positioned similarly to supine Watch fingers to avoid crush if “tucked” Legs are flexed and abducted above torso Low, standard, high, or exaggerated |
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Hemodynamic changes in lithotomy
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Central blood volume is increased after auto transfusion from raising legs
CVP, PAP, & PCWP all increase when trendelenberg added Reduction in pressure can cause hypoperfusion & ischemia in pt with PVD Use leg holders with foot support & low lithotomy Hypovolemia may not be recognized |
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Respiratory changes with lithotomy
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Obese, and GETA have decreased V/Q Ventilatory changes similar to supine
FRC not further reduced Diaphragm doesn’t shift further cephalad Concomitant use of Trendelenburg can cause decrease in FRC Awake, breathing patients V/Q unchanged |
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Precautions with lithotomy
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Both legs should be moved at same time to avoid hip dislocation, back/hip pain
Avoid abduction & external rotation of leg Can cause femoral nerve or lumbosacral plexus stretch injury Avoid extreme flexion of hip or knee Causes compression femoral/popliteal neurovascular structures Carefully pad point of contact on outer leg Peroneal nerve superficial course makes very susceptible to injury |
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Lateral Decubitus
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Supine for induction and intubation
Used for kidney and thoracic surgeries if inadequate exposure w/ supine position Use kidney rest for nephrectomy Can be used for craniotomy Orthopedic surgery of hip and shoulder |
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Lateral Decubitus cont.
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Shoulders, hips, head, and legs in alignment for turn.
Head & neck neutral on pillow, doughnut Dependant ear and eye free of pressure Pad all bony prominences |
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Lateral Decubitus cont. #2
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“Bean-bag” used to stabilize patient
Dependant arm padded, less than 90, non-dependant out of surgical field Axillary roll used to decompress shoulder neurovascular structures always document less than 90 degrees |
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CV and Resp. changes with lateral decubitus?
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Minimal CV changes
FRC decreased in dependent lung, and increased in nondependent lung V/Q greater in dependent lung in awake patient, but decreased after induction In nondependent lung ventilation is greater and compliance increased Perfusion greater in dependent lung in awake or spontaneous ventilation Positive pressure abolishes gravitational effect in anesthetized patient V/Q mismatches in 1 lung ventilation |
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Injuries associated with lateral decubitus?
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Ulnar nerve most commonly injured due to pressure on cubital tunnel
Common peroneal most common injured in lower extremity Brachial plexus injury caused by arm abduction more than 90 degrees Damage to dependent eye can occur if not protected |
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Sitting
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Elevation of head may vary
Lounge, lawn, or beach chair Hypotension is frequent Minimized if only 45 degrees vs 90 Less effect on lung volume than other positions |
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Complications with the sitting position
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VAE is the most feared complication
Air enters venous system because of negative pressure gradient between RA and veins at the operative site Incidence unknown and complications proportionate to amount air entering |
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Trendelenberg
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Any position where head is lower than rest of body
Used outside OR for treatment of hypotension Variable effect on blood pressure Hypotensive patients show no increase in MAP, increase SVR, and decreased CI. Normotensive patients compensate for increased CVP with vasodilation and decreased HR |
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CV changes with Trenddelenberg
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Hypovolemia may go unrecognized
Remember additive effect with lithotomy Increased venous pressure in face may cause orbital, pharyngeal & facial edema |
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Resp. changes with Trendelenberg?
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FRC is decreased proportionally with degree of trendelenberg
Mediastinal shift cephalad can cause mainstem intubation Risk for aspiration? |
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Injuries associated with Trendelenberg?
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Arms are vulnerable to injury if placed on arm boards.
Tendency to slip off, hyperextend, and abduct above head and stretch brachial plexus |