1) What is the most sensitive monitor for VAE

2) What is the 2nd most sensitive monitor for VAE

1) TEE- Air takes on a "smokey" appearance

2) Doppler- can detect Air bubbles as small as .25 ml

- Sounds like a "Mill Wheel" grinding sound vs. Normal "Swishing" sound when air is detected.

Where should you place the doppler to hear any VAEs best?

• Potentially lethal
• Air migrates to the heart creating compressible foam (reduced RV output) and irritates the conduction system.  Air bubbles obstruct the pulmonary capillaries preventing gas exchage
• Movement across a patent foramen ovale to the left side of the heart can also occur resulting in paradoxical air embolus

What is the treatment for VAE?

• Notify the surgeon
  • Will flood the field with Saline or  temporarily pack the site.  ie: bone wax to skull edges
• DC nitrous (If using)
• 100% oxygen
• Aspirate Air from CVP

11) Where should a multiple orificed CVP be placed in the Neursurgical pt?

2) How about if a single orifice CVP is used?

1) Right Atrium 2-3 cm BELOW the junction of the R. atrium and superior vena cava.

2) 3 cm ABOVE the junction of the r. Atria and superior vena Cava

If I notice a VAE-

What goals/ Types of things do I want to try and accomplish?

Another way to ask this: What can I do to the pt. to prevent entrainment of more air and/ or mitigate the badness that is coming?

1) Increase circulating volume

2) Treat hypotension

3) Head down position if possible

4) Turn pt. on L. Side

5) Jugular compression

6) Some advocate the use of PEEP.  This will increase CVP.  The rise in intrathoracic pressure MAY open a foramen ovale pushing air to the L. side of the heart (paradoxical air embolism)

1) Acute drop in ETCO2

2) Inc. in Peak Airway Pressures.

1) Antisaligogue

2) Inf. Vena Caval compression

3) Flexion of neck may cause tongue injury (microglossia)

4) Tongue injury d/t equipment in mouth

5) Omitting oral airway may result in tongue falling forward thereby causing injury.

1) What are some overall considerations regarding positioning in Neurosurgey? 

2) What specifically do I need to consider regarding the sitting position?

1) Many neuro surgeries are long

-pressure points

-Eye protection

-Thromboembolic devices

-Head up 15-20 degrees, Neutral if possible

-Axillary rolls if pt. is in lateral position

2) VAE

-Hypotension

-MAP monitored at the EAR

Fluid Management:

1) Where do I want my range to be?  (How full do I want the tank?)

2) Do I want to maintain a normal osmolarity?

3) Edema tends to occur in _______ tissue regardless of type.  Therefore goal is to prevent edema formation in normal tissue.

1) between slight hypovolemia and normovolemia

2) Yes

3) Injured

1) Why may I not want to use LR in Neurosurgery?

2) Is colloid use acceptable?

1) Lactate is converted to glucose in the Cori cycle.  Glucose EXTENDS areas of brain ischemia. 

-Blood sugars must be maintained at <200mg/dl

2) Yes

True or False:

1) I should do a complex Neuro exam prior to surgery and document.

2) Preop sedation is vital prior to entering the O.R.

3) During Neurosurgery brief periods of stimulation are followed by prolonged periods of no stimulation.

4)  To prevent injuty d/t tongs and/or increasing ICP we should extubate deep prior to transfer to PACU

1) True

2) False- can interfere with Neuro exam and lead to hypoventilation

3) True

4) False- We do want to prevent coughing/bucking and injury d/t tongs- and we also want to prevent increases in ICP.  However- we need to time emergence to prevent these things and ideally emerge the pt. in the OR in order to perform a Neuro exam prior to transfer.

1) Where does a contracoup injury occur?

2) Where does a coup injury occur?

1) Opposite side of intitial impact

2) Same side as impact.

Traumatic Head Injuries:

1) Describe a primary injury.

2) Describe a secondary injury.

1) Occurs within minutes- we can't change the outcome

2) Occurs within minutes to hours

-Causes: hypoxia, swelling, ischemia, hemorrhage, elevated ICP, hypo/hypertension, herniation

- we can treat these

Membranes covering the brain and spinal chord

Dura mater

Arachnoid mater

Pia Mater

Walkie- Talkie- Dead.

I'm usually a bleed from the middle meningeal artery that dissects the dura mater from the skull.   Sometimes I stop bleeding and let the pt. get their last words in before I start bleeding again. 

What type of bleed am I?

What is the treatment for Epidural Hematoma?

You only have one shot to kill Chuck Norris- where do you want to hit him with your bat to create an epidural Hematoma?

Evacuation is the treatment. 

Hit him in the Pterion- the skull is thinnest here.  Then run really fast- cause he is going to wake up and kick your ass then die.

This type of bleed is usually d/t disruption of bridging veins.  May occur in an anticoagulated patient or d/t trauma or tumor. 

Bleeding is between the dura mater and the arachnoid membrane.