Neurosurgical Intensive Care

optimal hemoglobin concentration for patients with brain injury has not been determined. In critically ill patients it has been demonstrated that, with the exception of patients with significant coronary artery disease, a conservative transfusion strategy is associated with better results than a liberal strategy, and transfusion to a hematocrit value of higher than 25-27 is not warranted. However, until data on patients with neurological disease are available, it remains prudent to maintain hemoglobin at about 10 g or hematocrit at 30.

In patients with severe head injury and stroke, as well as SAH, the presence of hyperglycemia is associated with a poor prognosis. Although stress is clearly a contributing factor, hyperglycemia itself can contribute to poor outcome. Thus hyperglycemia should be treated vigorously.

Neurological patients are prone to development of electrolyte disturbances; thus they should be measured daily, and appropriate replacements made. In particular, because of the relative impermeability of the BBB to ions, change in serum sodium and osmolality can have profound influence on movement of water across the BBB into neurons, and can exacerbate brain swelling/dehydration, causing coma and/ or seizures.

Hypo- and Hypernatremia Both hyponatremia and hypernatremia can occur in the neurological patient. The two major causes of sodium disturbances are: (1) iatrogenic and (2) CNS pathology related. Iatrogenic causes include administration of hypotonic fluids and the use of thiazide diuretics. Although normal hemostatic mechanisms will regulate sodium and water balance to maintain serum sodium within the normal range, persistent administration of hypotonic fluids, particularly in patients with poor renal functions or low cardiac output syndrome, will result in hyponatremia. The tonicity and composition of usual intravenous fluids are listed in Table 5.5. Following SAH, hyponatremia is particularly common, although only hypernatremia has been noted to be associated with a poor outcome. Disease-related causes include the development of diabetes insipidus, the syndrome of inappropriate antidiuretic hormone (SIADH), and cerebral salt-wasting syndrome (CSWS). It is extremely important to distinguish between the last two entities as the treatment is vastly different. With SIADH, the patient retains fluid, and excretes urine with high serum sodium and osmolality. Thus the appropriate treatment for SIADH is fluid restriction with or without diuretics, whereas with CSWS the

Table 5.5. Electrolyte composition of crystalloid and colloid fluids

Fluids

Osmolality

Na

Cl

Was this article helpful?

0 0
Supplements For Diabetics

Supplements For Diabetics

All you need is a proper diet of fresh fruits and vegetables and get plenty of exercise and you'll be fine. Ever heard those words from your doctor? If that's all heshe recommends then you're missing out an important ingredient for health that he's not telling you. Fact is that you can adhere to the strictest diet, watch everything you eat and get the exercise of amarathon runner and still come down with diabetic complications. Diet, exercise and standard drug treatments simply aren't enough to help keep your diabetes under control.

Get My Free Ebook


Post a comment