Sitting Craniotomies: A Review of Evidence-based Practice

Educational Objectives

The goal of this program is to improve procedures related to sitting craniotomies. After hearing and assimilating this program, the clinicians will be better able to:

1. Select a patient for whom sitting craniotomy is indicated.
2. Compare the benefits and drawbacks of Doppler monitoring vs transesophageal echocardiography in sitting craniotomy.

Summary

Indications of sitting craniotomy: eg, tumor resection, symptoms related to the posterior fossa, particularly acoustic neuromas, cerebellar metastasis, hemangioblastomas; also includes aneurysm clippings, placement of deep brain stimulator (most common surgery done in this position), and cervical spine surgery

Risks of surgeries: increased incidents of, eg, venous air emboli, hemodynamic instability, pneumocephalus, subdural hematomas, macroglossia, peripheral neuropathy

Benefits of surgeries: reduced surgical bleeding, lowered intracranial pressure (ICP), and less need for retraction and coagulation; facilitates surgical access and ability to operate with both hands; improves patient ventilation and gives the anesthesiologists an easy access to the airway; it may also decrease operative times

Patient selection: patient-related factors (cardiac pulmonary and cerebrovascular disease processes) considered; patients with intact hearing and facial nerve function along with a smaller-sized tumor are good candidates; patent foramen ovale (particularly presence of right-to-left shunt in heart) is relative contraindication; obese patients may benefit from being in sitting position from a pulmonary standpoint; sitting position means patients more likely to be hypotensive during a general anesthetic; increased risk with cerebrovascular disease

Pre-operative procedure: check the preoperative history and physical assessment of the cardiac, pulmonary, and neurologic comorbidities; assess baseline vital signs; this includes blood pressure (BP) and medications taken that morning, especially angiotensin converting enzyme inhibitors and angiotensin-receptor blockers

Induction: prompt neurologic examination at the end of surgery, facilitate intraoperative neurophysiologic monitoring, including somatosensory, motor-evoked, and brainstem auditory evoked potentials; monitor the facial nerve with motor-evoked potentials

Maintenance: depends on the patient; total intravenous anesthetic with propofol, remifentanil, and norepinephrine or phenylephrine infusions are used; obtain vascular access with extra monitors; this requires 2 peripheral IV lines and arterial line; a multi-orifice central line used to aspirate air; easier to aspirate larger volumes of air from the heart in case of air embolus in the catheter

Positioning for the sitting craniotomy: patient’s head is upright, fixed to the Mayfield head holder, which is secured to the bed on the patient’s thighs; use of Trendelenburg position potentially prevents a cervical spine injury because it prevents movement of the body; in one study, hemodynamically significant venous air emboli (VAE) was more common when patient’s bed was 45 degree vs 30 degrees

Precordial Doppler monitoring: traditionally placed over the right precordium; when transducer is turned on the classical “mill-wheel” murmur can be heard when air is in the heart; precordial Doppler monitoring is the most sensitive noninvasive monitor; it can detect as little as 0.05 mL/kg of air

Transesophageal echocardiography (TEE): most sensitive invasive monitor for venous air emboli (VAE); have someone experienced in monitoring; TEE can detect as little as 0.02 mL/kg of air

Venous air emboli: can be detected with, eg, TEE, Doppler device, end-tidal CO₂ testing, pulmonary artery catheters, cardiac output monitoring, electrocardiography; can manifest with hypoxemia, decreased end-tidal CO₂ levels, increased airway pressures, decreased cardiac output and BP, myocardial ischemia and arrhythmias, and cerebral ischemia

Intraoperatively: loss or decreased quality of evoked potentials because there is air between the surfaces of brain and skull

Postoperatively: delayed emergence, neurologic defects, headaches, decreased level of consciousness, and locked-in syndrome; treat with 100% FiO₂; complications include airway and tongue edema from excessive flexion of the head when in the sitting position; helpful to have 2 fingerbreadths under the chin; quadriplegia may occur; constantly check of position of the neck; also brain death, anosmia, and persistent cerebrospinal fluid leaks have been observed

Emergence: prompt neurologic examination with vigilance about increases in BP, coughing, and straining; the criteria for extubating are the same as with all craniotomies; maintain a secure airway if there has been excessive manipulation of the medullary structures, or with airway or tongue edema present; patients who are persistently hypertensive who were not preoperatively, can there may be brainstem compression, a hematoma, or brainstem ischemia

Readings

Ganslandt O et al. The sitting position in neurosurgery: indications, complications and results. a single institution experience of 600 cases. Acta Neurochir (Wien). 2013;155:1887–1893; Gasser T, et al. The combination of semi-sitting position and intraoperative MRI — first report on feasibility. Acta Neurochir (Wien). 2010;152:947–951; Gracia I, Fabregas N. Craniotomy in sitting position: anesthesiology management. Curr Opin Anaesthesiol. 2014;27:474-483; doi: 10.1097/ACO.0000000000000104; Rozet I, Vavilala MS. Risks and benefits of patient positioning during neurosurgical care. Anesthesiol Clin. 2007;25:631-x; doi:10.1016/j.anclin.2007.05.009; Stern Z et al. The influence of situational learning orientation, autonomy, and voice on error making: the case of resident physicians. Manag Sci. 2008;54:1553-1564; https://doi.org/10.1287/mnsc.1080.0862; Türe H et al. Effect of the degree of head elevation on the incidence and severity of venous air embolism in cranial neurosurgical procedures with patients in the semi sitting position. J Neurosurg. 2018;128:1560-1569; https://doi.org/10.3171/2017.1.JNS162489; Vossensteyn H, Westerheijden D. “Performance Orientation for Public Value: Dutch Myths and Realities in an International Perspective.” In Positioning Higher Education Institutions. SensePublishers, Rotterdam. https://doi.org/10.1007/978-94-6300-660-6_13.

Disclosures

In adherence to ACCME Standards for Commercial Support, Audio Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, members of the faculty and planning committee reported nothing to disclose.

Acknowledgements

Dr. Plaza was recorded at the 70th Annual Postgraduate Symposium on Anesthesiology, virtually, held May 1, 2021, and presented by the University of Kansas Medical Center. For future CME activities from this sponsor, please visit www.kumc.edu/community-engagement/ce.html. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

AN633603

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.