Question 1

College Answer

1)  Hyponatremia

Hyponatremia

•    Severe hyponatremia (<120 mEq/L) can cause significant and permanent neurologic injury or death. In the event of seizures or acute collapse relatively rapid initial correction may be required.
•    There is evidence that the severity and duration of hyponatremia may be related to cerebro pontine myelinolysis, normal saline and fluid restriction may be inadequate to increase sodium levels appropriately.
•    Some conditions such as cerebral salt wasting or large GIT losses may result in losses that may not be able to be replaced by other means.

2)  Traumatic brain injury

Traumatic Brain Injury

•     The rationale for hypertonic saline compared with normal saline
•     Better compensates for blood loss
•     Improved CPP
•     Reduces harmful inflammatory responses
•     May prevent cerebral edema.
•     Can be used as a continuous infusion
•     Obviates the need for osmolality testing

Previous animal studies and smaller clinical trials suggested better outcomes in patients with TBI after use of hypertonic saline solution. The safety profile has been good, and some evidence suggests a potential survival benefit when hypertonic saline is given. However The National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH) has stopped enrollment of patients with severe traumatic brain injury (TBI) into a Resuscitation Outcomes Consortium (ROC) trial testing the effects of hypertonic saline solutions given before arrival at the emergency department. as early as possible after TBI.
1073 patients 6 month analysis – no difference.

1.2        List the possible complications of hypertonic saline administration.

•      Hypernatremia
•     Hyperchloraemic acidaemia
•     Renal failure
•     CCF/Pulmonary Oedema
•     Neurological   SAH
•     rebound intracranial H/T

•      Central Pontine Myelinolysis

Discussion

Hypertonic saline for hyponatremia

It is straightforward: one wants to replace the missing electrolyte.

However, it may not be the first line therapy.

In brief summary:

• Sometimes, fluid restriction or other conservative measures may not be enough
• Severe prolonged hyponatremia is not without consequences
• Hyponatremia may have lifetheatening symptoms (such as coma and seizures), for which sodium replacement is the only sensible solution.
• Symptomatic hyponatremia should be managed with the infusion of hypertonic saline, so as to contribute sodium without contributing volume.

Hypertonic saline for traumatic brain injury

Osmotherapy for control of increased intracranial pressure is discussed in greater detail elsewhere. In brief summary:

• Hypertonic saline is probably better than mannitol
• Brain Trauma Foundation Guidelines do not recommend it, but they have not been updated since 2007.

Complications of hypertonic saline therapy

One review of 3% saline among neuroICU patients has a nice table (Table 1) which lists the potential adverse effects of hypertonic saline administration. I will reproduce the relevant parts of this table below. As you can see, the college answer for this section relies significantly on a source either identical to this one, or very closely resembling it.

• Hyperosmolarity
• Overshoot hypernatremia
• Congestive heart failure and pulmonary oedema
• Hypokalemia
• Normal anion gap metabolic acidosis
• Coagulopathy
• Phlebitis (hypertonic saline is a sclerosant)
• Renal failure (due to vasoconstriction)
• Decreased level of consciousness
• Rebound intracranial hypertension
• Seizures
• Central pontine myelinolysis
• Subdural and intraparenchymal hemorrhage

Lazaridis, Christos, et al. "High-Osmolarity Saline in Neurocritical Care: Systematic Review and Meta-Analysis*." Critical care medicine 41.5 (2013): 1353-1360.

Adrogué, Horacio J. "Consequences of inadequate management of hyponatremia." American journal of nephrology 25.3 (2005): 240-249.

Froelich, Matteus, et al. "Continuous hypertonic saline therapy and the occurrence of complications in neurocritically ill patients*." Critical care medicine 37.4 (2009): 1433-1441.