Nov. 30, 2023
There have been significant technical advances in the surgical resection of pituitary tumors and other skull-based tumors, principally due to the adoption of the endonasal, endoscopic, transsphenoidal approach, which often is a collaborative effort of a neurosurgeon and rhinologist. With these advances comes a significant decrease in the length of stay and the discomfort experienced by patients undergoing transsphenoidal resection. Patients are now discharged as early as the first postoperative day, but this also means there is a decreased ability to provide careful laboratory monitoring.
The most significant complication and cause of readmission after pituitary surgery is delayed hyponatremia (> 72 hours post-op), which can occur in up to 30% of patients and leads to significant patient discomfort as well as increased healthcare costs. The symptoms can include nausea and vomiting, syncope, intractable headache, lethargy, confusion, and even seizures. Often, the readmission requires an intensive care unit stay with close laboratory monitoring of sodium (every 4 to 6 hours) and interventions that include tight fluid restriction and hypertonic saline.
Although the classic "triphasic" response is taught during medical training, the entire progression does not occur in most patients after surgery, with isolated hyponatremia as the most common manifestation. Studies of outcomes for pituitary surgery have failed to identify consistent patient characteristics that could accurately predict who is at the highest risk. Moreover, prospective studies that have employed increased postoperative sodium monitoring have not been able to decrease occurrence rates and readmissions.
"The best approach is one that prevents hyponatremia from occurring in the first place," says Susan L. Samson, M.D., Ph.D., an endocrinologist at Mayo Clinic in Jacksonville, Florida. "There are accumulating data that fluid restriction in the postoperative period is effective in reducing hyponatremia and readmissions. We are seeing more pituitary centers implementing protocols that include restriction."
Dr. Samson and colleagues had previously published the success of a fluid restriction protocol in Neurosurgery in 2020, showing that delayed hyponatremia was reduced from 12.3% to 0% using one liter fluid restriction per day on postoperative days four to eight. The pituitary team at Mayo Clinic in Jacksonville, Florida, later published a meta-analysis of available data that was published in Endocrine Practice. Overall, there was a decrease in hyponatremia by 66% and readmissions by about 80%.
"The addition of fluid restriction protocols employed in the correct patients has clear benefits. We make sure, at the time of discharge, that our patients understand not only the protocol but also the very important reasons behind it."
In January 2021, Dr. Samson and the multidisciplinary pituitary surgery team implemented standardized protocols for patients undergoing transsphenoidal surgery at Mayo Clinic in Jacksonville, Florida. "This is really one of the least arduous but most efficacious protocols out there. Other centers may restrict fluids from the time of surgery through the first two weeks, which is really challenging for patients. However, we used the clues given by the physiology of postoperative vasopressin release, with timing corresponding to a range of postoperative days four to eight," says Dr. Samson.
The most successful fluid threshold in the literature appears to be 1,000 mL (32 fl. oz.). After incorporating this into the postoperative care at Mayo Clinic in Jacksonville, Florida, readmissions for hyponatremia for surgery of any skull-based lesion declined by 70% and to 0% for pituitary adenomas specifically. "The data shows that fluid restriction is safe for our patients based on postoperative day eight sodium and kidney function parameters," Dr. Samson states.
Dr. Samson concludes: "The addition of fluid restriction protocols employed in the correct patients has clear benefits. We make sure, at the time of discharge, that our patients understand not only the protocol but also the very important reasons behind it."
For more information
Winograd D, et al. An effective and practical fluid restriction protocol to decrease the risk of hyponatremia and readmissions after transsphenoidal surgery. Neurosurgery. 2020;87:761.
Perez-Vega C, et al. Fluid restriction after transsphenoidal surgery for the prevention of delayed hyponatremia: A systematic review and meta-analysis. Endocrine Practice. 2021;27:966.
Refer a patient to Mayo Clinic.