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.

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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.

Bibliography

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.

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.

Bibliography

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.

The effectiveness of prehospital hypertonic saline for hypotensive trauma patients: a systematic review and meta-analysis

Published on 1 December 2017

Blanchard, I. E.,Ahmad, A.,Tang, K. L.,Ronksley, P. E.,Lorenzetti, D.,Lazarenko, G.,Lang, E. S.,Doig, C. J.,Stelfox, H. T.

BMC Emerg Med Volume 17 Issue 1 , 2017

BACKGROUND: The optimal prehospital fluid for the treatment of hypotension is unknown. Hypertonic fluids may increase circulatory volume and mute the pro-inflammatory response of the body to injury and illness. The purpose of this systematic review is to determine whether in patients presenting with hypotension in the prehospital setting (population), the administration of hypertonic saline (intervention), compared to an isotonic fluid (control), improves survival to hospital discharge (outcome). METHODS: Searches were conducted in Medline, Embase, CINAHL, and CENTRAL from the date of database inception to November, 2016, and included all languages. Two reviewers independently selected randomized control trials of hypotensive human participants administered hypertonic saline in the prehospital setting. The comparison was isotonic fluid, which included normal saline, and near isotonic fluids such as Ringer's Lactate. Assessment of study quality was done using the Cochrane Collaborations' risk of bias tool and a fixed effect meta-analysis was conducted to determine the pooled relative risk of survival to hospital discharge. Secondary outcomes were reported for fluid requirements, multi-organ failure, adverse events, length of hospital stay, long term survival and disability. RESULTS: Of the 1160 non-duplicate citations screened, thirty-eight articles underwent full-text review, and five trials were included in the systematic review. All studies administered a fixed 250 ml dose of 7.5% hypertonic saline, except one that administered 300 ml. Two studies used normal saline, two Ringer's Lactate, and one Ringer's Acetate as control. Routine care co-interventions included isotonic fluids and colloids. Five studies were included in the meta-analysis (n = 1162 injured patients) with minimal statistical heterogeneity (I (2) = 0%). The pooled relative risk of survival to hospital discharge with hypertonic saline was 1.02 times that of patients who received isotonic fluids (95% Confidence Interval: 0.95, 1.10). There were no consistent statistically significant differences in secondary outcomes. CONCLUSIONS: There was no significant difference in important clinical outcomes for hypotensive injured patients administered hypertonic saline compared to isotonic fluid in the prehospital setting. Hypertonic saline cannot be recommended for use in prehospital clinical practice for the management of hypotensive injured patients based on the available data. PROSPERO registration # CRD42016053385 .

Expert commentary

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