SCOTTSDALE, ARIZ. – Comanaging neurosurgical patients requires a delicate dance between primary practitioners, surgeons, anesthesiologists, and, in some cases, the makers of implantable neurostimulators, according to perioperative medicine specialists.
Special considerations with patients scheduled for neurosurgical procedures include hypertension, fever, hyponatremia, and risk of deep vein thromboembolism (DVT) and coagulopathies, said Dr. Richard Huh, director of the inpatient medical consultation service at Rush University Medical Center in Chicago, at a meeting on perioperative medicine sponsored by the University of Miami.
For example, hospitalists are typically involved in the management of blood pressure in neurosurgery patients because of the importance of controlling intracranial pressure, Dr. Huh noted.
"The trick is for the blood pressure not to get too high or too low. The Handbook of Neurosurgery suggests a goal of 140 over 90 [mm Hg]," he said.
Patients with acute subarachnoid hemorrhage are at risk for vasospasm, most frequently within 7-10 days of hemorrhage. Hypovolemia is a common cause of vasospasm and should be avoided. Medications such as nimodipine (Nimotop) can help prevent this complication.
Patients undergoing spinal procedures tend to have low blood pressure from acute blood loss or intravenous pain medications, and may require hold parameters on medications to avoid complications from hypotension.
However, on the day following spinal surgery, some patients develop hypertension, and may require additional medications for BP control.
Hyponatremia
The reported prevalence of hyponatremia in hospitalized patients ranges from 1%-7%, and the rate is even higher in neurosurgical patients, possibility because the brain’s response to changes in osmolality. Clinicians managing neurosurgical patients should be aware of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt wasting, Dr. Huh said.
Cerebral salt wasting may be cause by damaged brain cells that affect sympathetic neural input to the kidneys, decreasing sodium resorption and an increase in atrial natriuretic peptide and brain natriuretic peptide.
The syndrome looks similar to SIADH, with high urinary sodium and osmolality, low serum osmolality, and decreased serum uric acid. But cerebral salt wasting is distinguished from SIADH by the presence of hypovolemia. Cerebral salt wasting is treated with saline and/or salt tablets.
DVT
Neurosurgical patients are at increased risk for DVT and pulmonary embolism compared with the general postoperative population. However, 2012 guidelines on antithrombotic therapy from the American College of Chest Physicians recommend against pharmacologic prophylaxis except for high risk patients, such as patients with intracranial masses. Dr. Huh said.
Implantable neurostimulators
Patients with implanted devices such as deep-brain stimulators for control of Parkinson’s disease, hypoglossal nerve stimulators for severe sleep apnea, or vagal nerve stimulators for epilepsy also require special consideration throughout the perioperative period.
Issues to consider when managing a patient with an implantable device include the device site and its proximity to the planned surgical field, indication for the device, comorbidities, and the patient’s goals for treatment, said Dr. Deborah Richman, section chief of preoperative services at Stony Brook (New York) University Medical Center.
"What do we do with device itself? This is a team approach, and we find that it’s best coordinated by our nurses in the preop holding area, because they know what time the surgery is, they have the device company rep’s phone number, they make sure the patient is there on time, and they put everything together to prevent delays on the day of surgery," she said.
In general, device manufacturers recommend turning devices off, and to turn the amplitude down to zero to prevent accidental activation of magnetic on-off switches.
The distance from the surgery to the pulse generator should be a minimum of 20 cm, and electrocautery, if used, should be bipolar rather than monopolar, Dr. Richman said.
Patients with implanted devices will also require prophylactic antibiotics to prevent potential bacterial seeding of the device or leads, she said,
Coordination of perioperative care "is best done with clinical management pathways, so that when you have one of these patients who present to you, you have a checklist that includes the device company’s phone number, and it’s an easy go-to, so that you don’t have to start from scratch each time," she concluded.
Dr. Huh and Dr. Richman reported having no financial disclosures.