Orthopedic Anesthesia Pt2 Flashcards
What are some important points of assessment necessary for upper body procedures preoperatively?
- Baseline vitals (HR and BP)
- Airway
- Pre-existing nerve conduction issues
- Examine pupils
Positioning for shoulder surgery typically includes which surgical positions?
- Beach chair/sitting
- Lateral decubitus
What are the cardiac consequences of sitting/Beach Chair position?
- ↓ CO & BP
- ↑ HR & SVR
Due to pooling of blood in lower body which decreases central blood volume.
What are the respiratory consequences of sitting/Beach Chair position?
- ↑ FRC & ↑ lung volumes
What are the neurologic consequences of sitting/Beach Chair position?
↓ CBF
How is venous air embolism prevented in a beach chair patient?
↑ venous pressure (above 0) at the wound to prevent a “suction” effect
VAE is common in which positions?
- Sitting
- Prone
- Reverse Trend
In what percent of the population is a patent foramen ovale present? Why can this be detrimental with VAE?
20 - 30 %
Air can maneuver from the right atrium to the left atrium and enter cerebral/coronary circulation
How does one treat venous air embolism?
Besides prevention…
- Inform surgeon → irrigation & occlusive dressing
- DC N₂O if being used
- Bilateral compression of jugular veins (prevent neuro consequences)
- Place patient in head down position to trap in right atrial apex
- Withdraw air through right atrial catheter
- CV & Resp support
The ultrasound transducer is being utilized to located venous air embolism in a patient. Where do you place the probe?
2ⁿᵈ - 3rd ICS right of sternum
Over the Right Atrium is most sensitive area
Though ultrasound over the right atrium is the most sensitive indicator of VAE (venous air embolism), the most definitive is….
TEE
The characteristic sound of a VAE is a _____________ murmur.
“Mill-Wheel” murmur
What would be an indicator of a decreased perfusion to the lungs?
sudden ↓ EtCO₂
________ of the neck in a sitting position patient can accidentally extubate them.
Hyperextension (head tilted back)
In a sitting position patient, where would one zero their art line?
Tragus of the ear (external meatus)
Establishes knowledge of brain BP & thus cerebral perfusion.
What are ocular conditions do we want to avoid due to the hypotension inherent to the sitting position?
- Retinal Ischemia
- Ischemia Optic Neuropathy
Also avoid corneal abrasion.
There is a 30cm distance from the patients heart to their brain. The patient’s BP measured on the arm is 120/70. What is the estimated BP in the brain?
30cm x 0.77mmHg = 23.1mmHg
120 - 23.1 = 96.9mmHg
70 - 23.1 = 46.9mmHg
The patient’s brain BP is 97/47 Thus indicating mild hypotension and possible correction.
A standing patient’s NIBP on the arm is 134/92. The distance between the patient’s knee and the NIBP cuff is 120cm. What is the BP in the patient’s knee?
120 x 0.77 = 92.4
134 + 92
92 + 92
Patient’s “knee” BP standing up is 226/184
How does the distance from the brain and heart affect the blood pressure?
Each cm of height between the brain and the heart causes a 0.77 mmHg drop in blood pressure (and vice versa)
ex: a 10cm distance between the brain and heart would cause the brain to have 7.7mmHg lower blood pressure (SBP/DBP/MAP)
What is the Bezold-Jarisch reflex?
Cardiac inhibitory reflex resulting in signification HoTN & Bradycardia.
Related to venous pooling (decreased preload) and decreased intraventricular volume
- Can potentially be mitigated by ondansetron (5HT3 antagonist)
What are the general anesthetic management options for shoulder surgery?
GETA
Regional
- brachial plexus block (ICS, supraclav)
What are possible complications of a brachial plexus block?
- Respiratory depression
- Horner Syndrome
- Hoarseness
- Dysphagia
Why can respiratory depression occur with brachial plexus blocks?
Hemidiaphragmatic Paresis from Phrenic nerve blockade.
What is the triad of Horner Syndrome?
- Ptosis (droopy eyelid)
- Miosis (pupil constriction)
- Anhydrosis (lack of sweat)
What are the respiratory consequences of a lateral decubitus position?
(VQ mismatch) ➡︎ hypoxemia
- ↓ ventilation of dependent lung.
- ↑ perfusion of dependent lung.
During mechanical ventilation in left lateral decubitus patient, which lung is overventilated?
Right lung (nondependent lung)
(dependent lung is underventilated d/t compression from abdominal and thoracic contents)
During mechanical ventilation in left lateral decubitus patient, which lung more perfused?
Left lung (dependent lung)
Where is an axillary roll placed on a lateral decubitus patient?
Caudad to the axilla to avoid compression of the neurovascular bundle.
Where should a pulse oximeter be placed in a lateral decubitus patient?
Dependent hand to ensure that there is no neurovascular compromise
(also frequently check radial pulse)
Elbow surgeries need what additional block (in comparison to shoulder surgeries) ?
Musculocutaneous nerve
