Anesthesia Student Survival Guide.pdf - Index of

290 ● AnesthesiA student survivAl Guide
catheter or tissue oxygen monitor). Current medications (especially blood
pressure agents, anticonvulsants, steroids, and sedative-narcotics) should be
reviewed and time of last dose noted. Blood products should be immediately
available for most procedures.
Intraoperative Considerations
General endotracheal anesthesia is indicated for most intracranial procedures
except for the “awake craniotomy” for epilepsy or resection of a lesion in the
motor or speech cortex. Invasive monitoring is indicated for all but the most
limited neurosurgical procedures (e.g., stereotactic biopsy or Burr hole drainage).
An arterial line will facilitate close management of blood pressure, carbon
dioxide, serum osmolality, hemoglobin, and oxygenation. Central venous access
should be considered based on likelihood of high volume blood loss (e.g., invasive
cancer, AVM resection) or air embolus (sitting position). Maintenance with
intravenous or inhaled agents should be individualized to the patient and the
proposed surgical approach. Opioids should be used judiciously; fentanyl and
hydromorphone are most commonly employed. The most stimulating periods
of surgery are head pinning, skin incision, and dural opening. Benzodiazepines
should be used sparingly to facilitate rapid emergence and postoperative neurologic
evaluation. Some anesthesiologists avoid Lactated Ringers because it is
hyponatremic and hypo-osmolar. Large volumes of normal saline, however,
may produce a non-anion gap metabolic acidosis, which must be considered in
assessment of arterial blood gases.
Rapid emergence and extubation is feasible after most neurosurgical procedures.
Exceptions include patients with profoundly decreased mental status
prior to surgery, significant intraoperative complications, acute traumatic brain
injury, marginal surgical hemostasis with high likelihood for re-exploration,
and procedures involving critical neural structures of the posterior fossa.
Neurovascular Surgery: Aneurysm Clipping/AVM Resection
Arteriovenous malformations are abnormal collections of veins and arteries
with convoluted vessel contributions that lack capillaries. These lesions may
feed functional cortex, which can be studied prior to surgery by selective barbiturate
injection in the awake patient. An AVM may be selectively embolized
in the radiology suite preoperatively to reduce bleeding.
These procedures are technically challenging, high-risk interventions with
unique considerations for anesthetic management. The complexity of the dissection,
the risk of rupture, and the surgeon’s plan for CSF drainage, burst-suppression,