Thursday, January 5, 2012

Up High, Down Low, Too Slow

You are the anesthesiologist on call and get paged by labor and delivery for an urgent C-section for failure to progress. You meet the patient for the first time in the operating room; she is 30 years old, G1P0 at 39 weeks, morbidly obese with gestational diabetes. Given her morbid obesity, you elect against general anesthesia and decide to place a spinal anesthetic instead. You position the patient, place local lidocaine, and go in with a standard spinal needle at L3-4 (you think; the morbid obesity makes it hard to feel landmarks) but are unable to get into the subarachnoid space. You try again one level higher at L2-3 and manage to get into the CSF. You inject 1.8mL of hyperbaric bupivicaine and 10mcg of fentanyl.

You lay the patient down and achieve surgical anesthesia quickly. The obstetricians begin working but because of the large pannus, they ask you to put the patient in steep Trendelenberg and have two nurses hold back the pannus as they work. Soon the patient becomes hypotensive. You run in fluids wide open and put a roll under the patient's right back to take pressure off the vena cava. The surgeons are getting into some blood loss, but not enough to explain the hypotension. She continues to remain hypotensive but is not particularly tachycardic. You ask her how she feels and she starts complaining of nausea and dyspnea. Her respiratory rate drops to 10, then 8, then 6. You end up intubating her emergently.

Challenge: What do you think happened?

Image shown under Creative Commons Attribution Share-Alike License, from Wikipedia.


Michelle said...

the hyperbaric (greater density than CSF) bupivicaine caused a high spinal when the pt was put in trendelenburg

Anonymous said...

due to her obesity, trendelenberg, pregnancy and no landmarks, she probably got a high spinal. High enough to give her hypotension + depress her resp rate.

Craig Chen said...

yes! exactly right
Up High, Down Low, Too Slow

This is an example of a high spinal anesthetic; the local anesthetic has traveled cephalad (possibly due to the large dose of bupivicaine and the steep trendelenberg position). This results in a sympathectomy, block of the cardiac accelerator fibers, hypoperfusion of the brainstem (nausea, respiratory depression), and blocking C3-C5 (diaphragm).

Source: UpToDate.

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