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Anesthesia Concepts 2 > Positioning > Flashcards

Positioning Flashcards

1
Q

OR table weight limit and length

A 
136 kg (300 lbs), 270 kg on the newer tables,
Length: 80.7 inches or 6'5
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2
Q

What is the most common operative position?

A

Supine; easy access to airway, arms for IV monitoring, less physiological changes than other positions

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3
Q

Supine positioning

A

tuck arms, use arm boards, draw sheet under the hip or torso, not the mattress, elbow pads, plasm supinated, UP. NOT PRONATED; lumbar support, slight flexion of hip and knees, safety strap

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4
Q

What are the 5 mechanisms of nerve injury?

A

Stretching, compression, kinking, ischemia, transection (stretching is most common, next compression)

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5
Q

Brachial plexus injury occurs in supine position when?

A

neck extended or turned to the side, excessive abduction of arm >90 degrees, arm falls off table. s/s would be shocks, numbness/weak arm

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6
Q

Radial nerve injury in supine position?

A

Radial nerve- due to external compression against humerus, surgical retractors, ether screen, mismatched arm board, repeated inflation
injury results in wrist drop/ weakness of abduction of thumb, and numbness of 1 and 2 ring fingers, inability to extend elbow.

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7
Q

Ulnar nerve injury in supine position?

A

*most common peripheral nerve injury
Compression in elbow groove between ulna and medial epicondyle of humerus. Stretched by elbow flexion, dislocation with pronated hand, compression against bed. More common in men (3x). Injury= CLAW HAND (cannot abduct or oppose 5gh finger, loss of sensation in 4th or 5th fingers, atrophy)

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8
Q

Cardiovascular changes with supine position?

A

Minimal effect on circulation and perfusion
Initial increase in return to heart, increased preload, SV, CO, BP. Baroreceptors activated which decrease sympathetic outflow= decreased HR, PVR. Beware of IVC masses.

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9
Q

Ventilatory changes with supine?

A

FRC decreases 800 ml d/t cephalad dispalcement of diaphragm. Lung volumes reduced by muscle relaxants reduces opposition to inherent elastic recoil of pulmonary tissues, overcome with PPV.

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10
Q

Supine cerebral blood flow changes?

A

Minimal due to tight autoregulation

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11
Q

Trendelenberg procedures

A

Laproscopy, GYN, abdominal, helps prevent air embolism, used during central line insertion; use braces and pads over arcomiocalvicular joint

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12
Q

Trendelenberg cardiovascular changes

A

Increases up to 1L venous return to heart. Reduced BF to LE. Compression of heart from abd contents, baroreceptors activated, makes shock syndromes worse in the long run.

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13
Q

Trendelenberg ventilatory changes

A

Compresses lung bases, decreases lung compliance, decreases FRC, PIP increases; V:Q mismatch, in apex: perfusion>ventilation; aspiration, ETT shifts to R mainstem, face/airway edema

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14
Q

Trendeleberg CBF

A

Increases intracranial vascular congestion due to gravity. Increases ICP. Intraoccular pressure increases.

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15
Q

Reverse Trendeleberg

A

Used to enhance exposure of upper abdomen, laparoscopic cholecystectomy, ENT surgeries; variation of sitting position; use footboard: excessive plantar flexion can cause anterior tibial injury= FOOT DROP

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16
Q

Reverse Trendelenburg Cardiovascular changes

A

Reduced preload, reduced C.O (20-40%), lowered BP, compensatory increased SNS tone, SVR, HR changes 30%. Activates RAS system, venous pooling in lower extremities, use stockings

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17
Q

Reverse Trendelenberg ventilatory changes

A

Abdomen does not impede diaphragm, FRC increases, ventilation is easier

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18
Q

Reverse Trendelenberg CBF

A

CBF decreases proportional to the degree of head up tilt (can be up to 20%), ICP decreases. Know the blood pressure at the circle of willis (move transducer up)

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19
Q

Describe the lithotomy position

A

Stirrups, hips flexed 80-100 degrees, legs abducted 30-45 degrees from midline, lower legs parallel to torso, watch femoral, sciatic, lower leg nerves (saphenous, common perineal especially)
Hip flexion beyond 110 degrees avoided.

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20
Q

Lithotomy position knee crutch style

Lithotomy position candy can stirrups

A
  1. Watch the popliteal nerve (tibial and common peronal nerve); also arms can fall off.
  2. Common peronal nerve injury*, sciatic, more acute flexion of the knees and hips
21
Q

Lithotomy lower extremity nerve injury percentages

A 
1: 3608 patients
78% common peroneal
15% sciatic
7% femoral
Most common with low body mass index, prolonged surgery, recent cigarette smoking, PVD, DM, obesity
22
Q

What procedures is the lithotomy position used for? And what nerves can be damaged?

A

GYN, GU, Rectal
Femoral, sciatic, obturator, lateral femoral cutaneous, saphenous, COMMON PERONEAL (compression of lateral aspect of knee against stirrup or lateral position) symptoms are foot drop, inability to evert the foot, loss of dorsal extension of toes

23
Q

Scatic nerve injury symptions?

A

Excessive external rotation of hips, pressure in sciatic notch from stretching, weakness or paralysis of muscles below knee, numbness in foot or lateral half of calf; foot drop

24
Q

Femoral nerve injury symptoms?

A

Compression at pelvic bring by retractor or excessive angulation of thighs and external rotation of hips, results in loss of flexion of hip and extension of knee; decreases sensation over superior aspect of thigh.

25
Q

Saphenous nerve injury symptoms?

A

Occurs when medial aspect of lower leg compressed against support bar; paresthesias medial and anterior side of calf

26
Q

Lower extremity compartment syndrome

A

Occurs when perfusion to an extremity is inadequate, resulting in ischemia, edema, extensive rhabdomyolysis from increased tissue pressure, occurs with long surgical procedures (>2-3 hours); occurs with lithotomy and lateral decubitus positions

27
Q

Lithotomy cardiovascular changes?

A

increases VR; increased preload with transient increase in CO and increase in Bp; perfusion to LE is reduced:
2 mmhg change for each 2.5 cm above or below heart

28
Q

Lithotomy ventilatory changes?

A

Depending on the degree of hip flexion, abdominal contents may be pushed up on the diaphragm and impede excursion, reduces lung compliance, TV and VC; aspiration risk

29
Q

Lithotomy cerebral changes

A

Transient increase in cerebral venous blood flow and increase in intracranial pressure with legs elevated

30
Q

Prone positioning procedures?

A

achilles, hemhorroid; back, cervical

31
Q

What types of beds are used for prone?

A

Wilson frame, Jackson table

horseshoe head rest, or with mirror; mayfield head tongs/pins (for back/cervical)

32
Q

Prone position

A

Head may be turned to side if adequate mobility, weight on bony structures, neck in neutral alignment, no pressure on eyes, breasts, genitals.

33
Q

Prone position eye injuries:

A

corneal abrasions, blindness (central vein or artery obstruction, sustained pressure on eye/retina)
Blindness risk factors: prone, operative hypotension, blood loss, crystalloid use excessively, anemia, smoker, diabetic, patient with HTN, male

34
Q

Prone position injuries?

A

Thoracic outlet syndrom: bundle of IJ, EJ and lymph come right under clavicle. Raise arm for 2 mins and check for decreased pulse ox or decreases pulse. Esp on left side.

35
Q

Prone position cardiovascular changes

A

IVC and aortic compression: hypotension! (use rolls)
Venous pooling in LE: hypotension! (use SCDs or stockings)
*HYPOTENSION! anticipate and give fluids

36
Q

Prone position ventilatory changes

A

V:Q mismatch:
anterior perfusion> ventilation
Posterior ventilation>perfusion
Cephalad displacement of diaphragm, lung compliance decreases, PIP increases, WOB increases. = use rolls/bolsters to free chest. PPV overcomes effects

37
Q

Prone position CBF

A

turning head obstructs venous drainage leading to increased cerebral volume and ICP; excessive flexion or turning obstructs vertebral artery flow

38
Q

Lateral decubitus position procedures

A

thoracotomy, kidney, shoulder, hip

39
Q

Lateral decubitus position

A

Keep head supported and neutral; use axillary roll; pad between knees, flex dependent leg (saphenous nerve injury)
Anterior/posterior support, bean bag, safety strap between head of femur and illiac crests

40
Q

Lateral positioning cardiovascular changes

A

minimal change, no change in CO unless VR is obstructed (kidney rests against vena cava),
noninvasive BP will be different in each arm.

41
Q

Lateral position ventilatory changes

A

Awake and spontaneous breathing: Dependent lung is better perfused and ventilated, but FRC, VC, TV decrease
Anesthetized and spontaneously breathing: nondependent lung better ventilated and dependent lung better perfused (VQ mismatch)
anesthetized, mechanically ventilated: nondependent lung is overventilated and dependent lung is overperfused (worse VQ mismatch)

42
Q

Lateral position CBF:

A

Minimal change unless extreme flexion of head

43
Q

Sitting position

A

uses mayfield tongs to keep head in placed, used for cranial surgery, shoulder, humeral procedures, facilitates venous drainage, excellent surgical exposure/access; avoid excessive cervical flexion, want 3 FB between mandible and sternum, avoid rigid bite block for tongue ischemia; flex knees and hips to avoid sciatic injury, SCD

44
Q

Sitting position cardiovascular changes

A

Pooling of blood into lower extremities decreases preload, CO and BP, HYPOTENSION; HR and SVR increase as a compensatory measure, treat with IVF, vasopressors, adjust anesthetic depth, stockings, SCD

45
Q

Sitting position ventilatory changes

A

Lung volumes increase, WOB is easier, easeri to mechanically ventilate

46
Q

Sitting position CBF

A

Gravity, CBF decreases, ICP decreases; check BP at circle of willis

47
Q

Venous air embolism

A

VAE: at risk during anytime where surgical site is above the level of the heart, inability of venous sinuses to collapse, lethal complication. S/S: change in heart tones (wind mill murmur) heart at parasternal border (2-6 IC space), dysrhythmias, hypotension, denaturation, decreased EtCO2. Nitrogen in exhaled gas, tachycardia. Find with TEE or precordial doppler to hear the air entrained.

48
Q

Treatment of VAE

A

Flood surgical field with NS, apply wax to cut bony edges, close any open vessels, D/C nitrous oxide, place on 100% Fio2, peep, Trendelenberg, aspirate air from R artium via catheter.

Anesthesia Concepts 2 (10 decks)

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