NIHR Signal Hypertonic saline as effective as normal saline for trauma patients
Published on 13 March 2018
Solutions more concentrated than normal, such as hypertonic saline, are as good as those more usually given to trauma patients with severe blood loss. Survival to hospital discharge was the same in patients treated before arrival at the hospital with either type of fluid.
There are around 20,000 cases of major trauma per year in England. Outcomes for patients have improved in the UK over the last 25 years, but as there is still room for improvement this review sought to find evidence that supported or challenged the convention that normal saline is always best.
Hypertonic solutions are given to patients in a lower volume, and so can be carried in more compact packaging. They could be preferred for transportation by emergency services if they are equally safe.
- Emergency and urgent care, Medicines, Acute and general medicine
Why was this study needed?
Traumatic injury leads to more than 5.8 million deaths every year across the world. In 2010, it was estimated that there are at least 20,000 major trauma cases in England each year, of which around 5,400 result in death and several others in disability. Many of these are due to road traffic collisions.
Trauma patients with blood loss and low blood pressure need intervention by emergency staff before arrival at the hospital, and this may include fluid therapy. In the UK this is almost always with fluid which has a similar concentration to normal blood. Hypertonic saline is much more concentrated than normal human fluids and draws fluid into the bloodstream from the tissues, increasing the patient’s circulatory volume further.
Hypertonic fluids have been compared previously with isotonic fluids in various settings, but findings have been inconclusive. This study compares the two interventions in out-of-hospital care.
What did this study do?
This systematic review of five randomised control trials compared hypertonic 7.5% saline (about eight times the concentration of isotonic saline) with isotonic or near isotonic fluids in 1,162 trauma patients from North America, Australia or Finland. Patients were young adults aged 31 to 50 years.
The primary outcome was survival to hospital discharge, reported as in each study and assessed through a combined relative risk. Secondary outcomes were summarised as in the original studies, and they included longer-term survival, length of hospital stay and disability.
One study did not report enough data to assess bias. For the other studies, the risk of bias was low.
What did it find?
- Survival to discharge did not vary with the type of fluid patients received (combined relative risk 1.02, 95% confidence interval 0.95 to 1.10).
- Most data (58%) came from a single 2011 trial of 632 patients.
- One trial showed a greater change in systolic blood pressure in patients treated with hypertonic saline, favouring this type of fluid.
What does current guidance say on this issue?
The NICE technology appraisal guidance on pre-hospital initiation of fluid replacement therapy in trauma recommends initiating fluid replacement in the ambulance en route to hospital in patients without a palpable pulse and when clinical judgement in the presence of severely reduced blood volume deems it necessary. It recommends using normal saline (isotonic fluids).
The guidance recommends assessing further different protocols for pre-hospital care of trauma patients.
What are the implications?
Hypertonic solutions seem to produce similar clinical outcomes in hypotensive trauma patients compared with isotonic solutions. These results are in line with previous findings.
Hypertonic solutions are given to patients in lower volumes, allowing for lighter and more compact packaging for the same clinical outcome when compared with isotonic solutions. This presents an advantage when space and weight are limited, as they are for helicopter rescues, for example.
The findings suggest that emergency teams may benefit from carrying hypertonic instead of isotonic solutions. Additional research is needed to validate these results and identify the optimal use of hypertonic solutions, particularly the optimal volume for hypotensive trauma patients.
Citation and Funding
Blanchard IE, Ahmad A, Tang KL, et al. The effectiveness of prehospital hypertonic saline for hypotensive trauma patients: a systematic review and meta-analysis. BMC Emerg Med. 2017;17(1):35.
This study was not funded.
Brake. Road collisions responsible for 1 in 5 trauma admissions to hospitals. London: Brake; 2017.
National Audit Office. Major trauma care in England. London: The Stationery Office; 2010.
NICE. Major trauma: assessment and initial management. NG39. London: National Institute for Health and Clinical Excellence; 2016.
NICE. Pre-hospital initiation of fluid replacement therapy in trauma. TA74. London: National Institute for Health and Clinical Excellence; 2004.
Rossaint R, Bouillon B, Cerny V, et al. The European guideline on management of major bleeding and coagulopathy following trauma: fourth edition. Crit Care. 2016;20:100.
Clear fluids are commonly given to hypotensive trauma patients during prehospital evacuation, but we still don’t know for certain which fluids are best. Hypertonic fluids were reported as superior to isotonic fluids in some previous animal studies, but this has not been confirmed by combining all of the randomised clinical (human) data.
Such a discrepancy should remind us to be cautious about animal studies, which are designed to generate hypotheses, rather than to inform practice.
It is imperative to design, support, and undertake high-quality prehospital studies to answer clinical questions regarding fluid resuscitation for trauma patients.
Dr David Naumann, Research Fellow, NIHR Surgical Reconstruction & Microbiology Research Centre, Queen Elizabeth Hospital, Birmingham