Hypertonic Saline a Solution for Controlling Intracranial Pressure in TBI Patients

Newswise — Controlling intracranial pressure (ICP) is an essential component of effectively treating patients with traumatic brain injury (TBI). TBI patients may develop increased ICP as a result of edema (brain swelling), blood clots, subdural hematomas, or other intracerebral hemorrhages. Because the brain is surrounded by the rigid skull, high ICP can cause compression or squeezing of the softer brain tissue, preventing enough blood from getting to the brain tissue. The result can be damage to brain cells. Even a short period of increased ICP can cause permanent damage. Raised ICP, along with hypotension and hypoxia, can increase the mortality rate in TBI patients by 70 percent. TBI survivors are often left with significant cognitive, behavioral, and speech disabilities, and some patients develop long-term medical complications, such as seizures.

Osmotic therapy is the cornerstone of nonsurgical management of ICP. There are theoretical reasons why hypertonic saline (HTS) may be a more effective and safe osmotic agent than mannitol. Neurosurgeons at Hennepin County Medical Center (HCMC) in Minneapolis recently assessed the effectiveness of HTS as a single osmotic intervention for controlling ICP and its effect on cerebral perfusion pressure (CPP) and brain tissue oxygen (PtO2).

The results of this study, Hypertonic Saline (HTS) and its Effect on Intracranial Pressure (ICP) and Brain Tissue Oxygen (PtO2), will be presented by Archie Defillo, MD, 4:15 to 4:30 p.m. on Monday, April 24, 2006, during the 74th Annual Meeting of the American Association of Neurological Surgeons in San Francisco. Co-authors are Gaylan L. Rockswold, MD, PhD, Jon Jancik, PharmD, and Sarah B. Rockswold, MD.

HTS produces massive movement of water out of edematous swollen cells and into the blood vessels. This movement of water out of the brain can reduce swelling and improve cerebral blood flow. This specific action of HTS is due to its reflection coefficient of 1. The high numbers of particles in the solution pull water from a low-pressure compartment to a higher-pressure one. Compared with another osmotic diuretic such as mannitol, in which the reflection coefficient is 0.9 (allowing some leakage outside the blood vessels), HTS will not leak outside the capillaries in the presence of an intact blood-brain barrier.

An analysis of 24 consecutive TBI patients (21 males and 3 females, ages 17-64, mean age: 37.5) admitted to the surgical intensive care unit (SICU) at HCMC was conducted. The use of other medications to control ICP was an exclusion criteria to prevent inaccurate results. Blood pressure (BP), mean arterial pressure (MAP), central venous pressure (CVP), heart rate, temperature, intake and output were monitored hourly. Serum sodium, osmolality, and arterial blood gases were checked every six hours. Hemoglobin levels, blood urea nitrogen (BUN), serum potassium, chloride, magnesium and phosphate levels were checked daily.

The goal of the therapy was to maintain an ICP of less than 20 mmHg, a CPP between 55 and 70 mmHg, and PtO2 of 20mmHg or higher. When ICP increased to more than 20 mmHg, 30 milliliters of a 23.4-percent solution of HTS was administered as a single dose or repeated doses to control ICP levels. Hemoglobin levels less than 10 gr/dl were corrected via blood transfusion to maintain a constant oxygen delivery (VDO2).

The following results were noted:

"¢Mean absolute value for ICP showed a 35 percent decrease compared to baseline. In the three different subgroups, the significant decrease occurred within the first hour after HTS infusion, with the following decreases noted: 26-percent in group 1, 51 percent in group 2, and 44 percent in group 3.

"¢CPP mean absolute value increased by 14 percent. CPP values were recorded in three subgroups: 40-54mmHg in group 1, 55-69mmHg in group 2, and 70 mmHg and higher in group 3. There was a mean increase of 40 percent in group 1, 12 percent in group 2, and 3 percent in group 3. In all groups, there was a sustained response for four hours after the initial infusion.

"¢PtO2 values were recorded in three different subgroups: 10-19 in group 1, 20-29 in group 2, and 31 mmHg and higher in group 3. None of the means were statistically different in the three subgroups; there was a steady linear increment ranging from 2.9 percent after the first hour to 25 percent by six hours after infusion.

"There were no complications as a result of this treatment, so in conclusion, HTS is a viable option for decreasing ICP and improving CPP and PtO2 in TBI patients," said Dr. Defillo. "Studying a larger patient pool would provide an even better assessment of the effectiveness of HTS as a treatment option for TBI," concluded Dr. Defillo.

Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 6,800 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system, including the spinal column, spinal cord, brain and peripheral nerves.