ssfety and positioning Flashcards
Erect to supine position causes increased venous return which presents as:
increased preload, stroke volume (SV), cardiac output (CO), increased MAP
MAP maintained within a narrow range during postural
changes in
NON-ANESTHETIZED setting.
GA, muscle relaxation, +pressure
ventilation and regionals interfere with
autoregulation causing
anesthetized patients more vulnerable to CV effects
related to positioning.
• HR, CO and BP decreased d/t CV and CNS
depression
when should positioning be delayed?
when pt is unstable
MAP decreases ___ per inch change
between the heart and a body region.
2 mmHg
what position exacerbates negative response r/t respiratory
trendelenburg
[even worse with insufflation]
Perioperative Contributing Factors to nerve injury
positioning devices
length >4 hrs
anesthetic techniques
GA, NMB, regional risks to nerves?
GA = loss of pain response
NMB = increased mobility and stretching
Decreased MAP = decreased neuronal perfusion
Regional can cause injury but mostly d/t
technique, hematoma or needle trauma.
patient related contributing factors to injury?
underweight
obese
muscular
HTN, DM, PVD, alcoholism, smoking
Most frequently reported injury after surgery
and anesthesia; most commonly injured nerve.
ulnar nerve
Increased incidence of ulnar nerve injury?
male,
preexisting neuropathy,
prolonged hospital stay,
extreme body habitus
how to Avoid Ulnar Nerve Injury?
- Padding, PADDING, PADDING
- Supinate when possible
- Abduct arms < 90 degrees
- With armboards, supinate forearms
- When tucked, arms neutral with palms inward
- Avoid extensive elbow flexion
Risk with all positions but especially
with arms over the head, abducted
and/or head rotated.
Brachial Plexus Injury
Brachial Plexus Injury causes
- Poorly positioned axillary rolls
• Positioning devices such as arm boards (falling off) or
shoulder braces (steep T-burg)
• Sternal retractors during cardiac surgery
Most reported neuronal injury, really the second.
Primarily with regional
techniques with anticoagulants
and for pain management
Spinal
Cord Injury
Spinal Cord Injury can cause
Hemiparesis and quadriplegia
with sitting position (rare)
how to avoid spinal cord injury?
Avoid hyperflexion of neck
(2 fingerbreadths)
• Consider SSEPs, MEPs.
Radial or Circumflex nerve injury causes
Ether screen, retractor pole
Suprascapular nerve injury causes
Lateral position, dependent arm
with shoulder circumducted
Sciatic nerve injury causes
Inadequate padding supine or sitting
Common peroneal, Posterior tibial, Saphenous nerve injury causes
Lithotomy stirrups, bar, knee support
Obturator nerve injury
Lithotomy with excessive hip flexion
Pudendal nerve injury cause
Traction against perineal post of
fracture table
Postoperative Visual Loss (POVL) causes
• Ischemic Optic Neuropathy (ION) • Central Retinal Artery Occlusion (CRAO) • Central Retinal Vein Occlusion • Cortical Blindness • Glycine Toxicity
account for 81% of all POVL cases
Ischemic Optic Neuropathy (ION)
• Central Retinal Artery Occlusion
(CRAO)
accounts for 89% POVL after prone spinal cases
Ischemic Optic Neuropathy (ION)
Central retinal and posterior
ciliary arteries are
“watersheds” and highly
vulnerable to obstructed
blood flow
Ischemic Optic Neuropathy (ION)
Predisposing Factors: Ischemic Optic Neuropathy (ION)
Male, HTN, CV dz, obesity, DM
• Spinal surgery, prone, long
surgery time, high blood
loss, low HCT, SBP < 100
Most common cause: ION?
decreased perfusion
Central Retinal Artery Occlusion
(CRAO) causes
CP Bypass, hypotension,
increased extraocular pressure
Central Retinal Vein Occlusion causes
Hypertension, CV dz, obesity,
glaucoma, Sickle Cell anemia
Results from
ischemia or trauma from emboli,
CP bypass, decreased perfusion
cortical blindness
L-arginine deficiency = accumulated ammonia = vision loss (very rare syndrome)
Glycine toxicity:
Well-known complication of
sitting position but can occur
anytime the surgical sight is above
the right atrium.
Venous Air
Embolism (VAE)
Up to 35% patients with venous embolism have
have an undiagnosed patent foramen ovale (PFO).
Paradoxical air embolism (PAE)
occurs
through a PFO when RA
pressure >LA pressure
Small VAEs can be absorbed BUT
large VAEs cause
hypotension,
dysrhythmias, CV arrest, death.
• VAEs can be aspirated through
CVL placed in the RA at the junction of the SVC
gold standard to monitor for VAEs?
Transesophageal Echo (TEE)
most used way to monitor for VAEs, r/t cost
Precordial Doppler
• Probe over 3rd – 6th intercostal
space, R of sternum
