Acute and subacute toxicity of 7.5% hypertonic saline-6% dextran-70 (HSD) in dogs. 2. Biochemical and behavioral responses

The role of hypertonic saline dextran in trauma resuscitation

Modern trauma management has recognized the importance of using conservative fluid resuscitation regimes in order to prevent complications from fluid overload arising. Hypertonic/hyperoncotic fluids appear to provide an ideal means of facilitating this, requiring only small volumes to rapidly elevate blood pressure. Hypertonic saline dextran (HSD) was introduced in 1985 but its take up has been slow, a large part of this has been due to the lack of human trials and concerns about complications.

The current evidence has been reviewed and it is clear that HSD is an efficient means of correcting hypotension, doing so mainly by the mobilizing endogenous water. It is becoming apparent that early administration has the potential to modulate the inflammatory cascade in patients at risk of developing adult respiratory distress syndrome (ARDS) and multiorgan failure. This is reflected in the handful of human trials that show a trend towards increased survival (particularly for head injuries) and a possible reduction in ARDS. The side effect profile appears to be good, even in the presence of dehydration or penetrating trauma.

Published human trials have methodological problems and lack of power of study this has led to a reliance on animal studies. Clearly there is great potential, but before large-scale prehospital usage can be justified further well-conducted randomized human trials are needed.

Evaluation of the local irritation potential of hypertonic saline-dextran (HSD) in mice and rabbits

Recent questions have renewed concerns regarding possible irritation associated with intravenous (i.v.) injection of 7.5% hypertonic saline (HS) or hypertonic saline-dextran (HSD: 7.5% NaCl and 6% Dextran-70). This study investigated local injection site irritation associated with i.v., paravenous (p.v.), intramuscular (i.m.) and subcutaneous (s.c.) injection of HSD or its individual components. Mice (n=10 per group per time point) and rabbits (n=10 per group per time point) were infused i.v. with the maximum tolerated dose (28 or 20 ml kg(-1), respectively) of HSD, HS, Dextran-70 (D-70) or lactated Ringer's solution (LR). Animals were observed at 1,2 and 4 h after injection and then twice daily until euthanized on day 3 or 14. In irritation studies, 24 rabbits were randomized to receive the four fluids and they were evaluated histologically at 4, 24, 48 or 72 h after i.v., p.v., i.m. or s.c. infusion. The sites were observed immediately after injection, at 4 h and then twice daily until euthanasia. In surviving mice, bruising of the tail was observed in 6/18 and 5/19 animals in the HSD and HS groups, respectively, compared with 0/20 animals in the D-70 or LR groups. Sloughing of the tail was eventually observed in two HSD-infused and three HS-infused mice, compared with none in the other groups. More bruises, hematomas and blebs were observed after i.v. or s.c. injection of HS and D-70 than LR or HSD in the rabbit irritation studies, but the differences among groups were not statistically significant. In the acute toxicity study in rabbits, bruising at the site of injection was observed in 7/20 and 5/14 surviving animals from the HSD and HS groups, respectively, but none was observed in the LR or D-70 groups. These data suggest that, if infused over 5-10 min into a peripheral or central vein, a therapeutic dose of HSD (4 ml kg(-1)) should not induce any greater inflammation on the vein than LR. However, if significant extravasation of hypertonic fluid occurs, the possibility of localized, focal necrosis might be expected to occur.

Traumatic brain injury in infants and children: mechanisms of secondary damage and treatment in the intensive care unit

Unfortunately no specific pharmacologic therapies are available for the treatment of TBI in patients. Current investigation of contemporary therapies for the treatment of TBI consists of recycling of previously tested therapies in the era of contemporary neurointensive care. These therapies include hypothermia, decompressive craniectomy, osmotherapy, and controlled hyperventilation. It is hoped that more detailed knowledge regarding the dominant pathophysiologic mechanisms associated with TBI-excitotoxicity, CBF dysregulation, oxidative stress, and programmed cell death-will catapult an efficacious intervention from the laboratory bench to the bedside. This intervention may be a potent agent targeting a single dominant pathway, a broad-spectrum intervention such as hypothermia, or, more likely, a combination of therapies. Meanwhile, practitioners must offer meticulous supportive neurointensive care using clinically proven therapies aimed at minimizing cerebral swelling for the management of pediatric patients who are victims of TBI.

Promising strategies to minimize secondary brain injury after head trauma

OBJECTIVE

To review novel therapeutic approaches in the treatment of severe traumatic brain injury.

DESIGN

Eighty-three studies were reviewed specific to the treatment of traumatic brain injury, in either experimental models or in patients.

CONCLUSION

Four therapeutic strategies appear to be the most promising approaches currently in clinical trials for severe traumatic brain injury: a) the novel pharmacologic agent dexanabinol; b) hypertonic saline; c) mild hypothermia; and d) decompressive craniectomy. Each of these therapies share the common feature of targeting multiple mechanisms, suggesting this may be an important factor to the development of a successful approach to severe traumatic brain injury.