How would you proceed and induce and maintain anesthesia?

This is what we did:

We placed the patient in the sitting position on the operating room table, placed standard ASA monitors and 6 L/min oxygen by face mask on the patient. Invasive monitoring of arterial blood pressure was discussed by the anesthesia team, but an arterial line was not placed in the upper extremities in order to preserve vessels for potential future AV fistulas. The option of a lower extremity dorsalis pedis arterial line was felt to be suboptimal secondary to infectious risk and poor access to it.  Therefore, monitoring of blood pressure during the case was via a noninvasive sphygmomanometer which was cycled every 1- 2 minutes during critical periods, otherwise every 3 minutes.

The thoracolumbar region was prepped and draped sterilely for the combined spinal/epidural. Local was applied to the skin at the L3/4 level with 1 ml lidocaine 1%. The 17 gauge Tuohy needle was placed atraumatically using a midline approach with the loss of resistance technique with saline/air mixture. The epidural space was located with one attempt. Then a 27G Whitacre spinal needle was advanced through the Tuohy needle until CSF was visualized in the spinal needle. No paresthesias and no blood were obtained from either the Tuohy or the spinal needle. 1.6ml hyperbaric bupivacaine 0.75%, with 20mcg fentanyl were administered intrathecally after good CSF flow with syringe aspiration. The spinal needle was removed, and an 18 gauge wire-reinforced end-holed epidural catheter was advanced 4cm into the epidural space via the Tuohy needle. The Tuohy needle was removed from the patient’s back, and the epidural catheter was taped to the patient’s back with sterile tegaderm.

We used a hyperbaric local anesthetic for the spinal in order to be able to better control the level of the dermatomal spread with changing the patient’s position on the OR table. The hip surgery itself only requires dermatomal blockade below T11. However, if the case were prolonged, and we wished to take advantage of the surgical anesthesia provided by the spinal for the longest period of time without excessive sympathectomy and hypotension, we optimally aim to achieve a higher level of sensorimotor blockade at a higher thoracic level, such as T6. The optimization of the duration of the level of sensory blockade with a hyperbaric spinal has not been specifically addressed in the literature with all patient parameters being similar. However, literature data suggests that adding epinephrine to hyperbaric spinal bupivacaine does not predictably prolong its duration. However, adding epinephrine to most other spinal local anesthetics, including isobaric bupivacaine, does prolong the duration of action.

Isobaric spinal medication could also be a good option, if the patient will be sitting up for a prolonged period of time during the epidural catheter advancement after the spinal. Hypobaric spinal medication is also a good alternative if the patient will remain in the lateral decubitus position with the operative side up, such as with a fractured hip.

Sensory blockade to light touch and loss of cold sensation from the spinal was confirmed below the T8 dermatome. After initial surgical incision was made, the patient became hypotensive and required a phenylephrine infusion to support her blood pressure, followed by 2 units PRBC. The patient was able to communicate throughout this period of hemodynamic instability, and then was hemodynamically stable for the remainder of the case. The target range of acceptable blood pressure varies from patient to patient, depending upon comorbidities as well as starting values and lability of blood pressure. One of the greatest advantages of regional anesthesia is the ability to monitor serial neurologic exams as a means of assessing cerebral perfusion during periods of critical hypotension. With adequate patient communication and responses, we were able to gauge her ability to tolerate the hemodynamic swings during the case. During the five-hour intraoperative period, her systolic blood pressure ranged from 80-148, and her diastolic blood pressure ranged from 35-80. Her baseline preoperative blood pressure was 140/75. However, it seems reasonable that the maintenance of cardiac stroke volume and inotropy with regional anesthesia may be an underlying mechanism to explain the preservation of cerebral perfusion during periods of hypotension. Of course, eventual preload replacement is essential in order to maintain ventricular filling pressures.