Is the Use of Hypertonic Saline Effective in Reducing Intracranial Pressure After Traumatic Brain Injury in Dogs?

a Knowledge Summary by

Alexandra Tischer DrVetMed, Vets Now1*

Ava Firth DVM, DACVECC1

1Vets Now Support Office, Penguin House, Castle Riggs, Dunfermline, Fife, KY11 8SG
*Corresponding Author (a.tischer@gmail.com)


Vol 2, Issue 2 (2017)

Published: 15 May 2017

Reviewed by: Shailen Jasani (MA, VETMB, MRCVS, DACVECC) and Bruce Smith (BVSc, MS, FANZCVS, DACVS)

Next Review date: 15 May 2019


Clinical bottom line

Hypertonic saline appears to be effective in reducing intracranial pressure after traumatic brain injury in dogs in experimental studies.

Question

In dogs with traumatic brain injury, does hypertonic saline, compared to lactated Ringer’s solution, reduce intracranial pressure?

Clinical scenario

A three year old 15kg male entire Terrier cross is brought in after running into the road and colliding with a car. It is in hypovolaemic shock and after fluid resuscitation (25ml/kg LRS in 15 minutes) the only visible injuries found are epistaxis and a fractured jaw. However, the dog is stuporous and consciousness does not seem to improve with stabilising cardiovascular parameters.

Would treatment with hypertonic saline be beneficial for this dog?

The evidence

Nearly all available evidence for this PICO question comes from experimental studies. How much experimental and clinical traumatic brain injury differ is unclear.

Summary of the evidence

Abbreviations Used

CPP    cerebral perfusion pressure

CVP    central venous pressure

ICP      intracranial pressure

LRS     lactated Ringer’s solution

MAP    mean arterial pressure

Prough (1986)
Population: Dogs
Sample size: 17
Intervention details: After 30 minutes of experimentally induced haemorrhagic shock (MAP <50mmHg) dogs were resuscitated with hypertonic saline solution or LRS.

Study design: Randomised, experimental study.
Outcome Studied: Systolic and diastolic blood pressure, cardiac output, MAP and ICP.
Main Findings
(relevant to PICO question):
ICP after resuscitation with hypertonic saline was lower than after LRS while restoring systolic blood pressure and cardiac output to the same level.
Limitations:
  • experimental study
  • no brain injury or increased ICP to begin with
  • small number of cases

Gunnar (1988)
Population: Laboratory Beagles
Sample size: 22
Intervention details: Hypovolaemic shock and closed head injury were simulated via bleeding of 40% of blood volume and epidurally inflated balloon in 17 dogs. This was maintained for 1h, after that resuscitation with the shed blood and either 3% hypertonic saline (6 dogs), 0.9% saline (5 dogs) or dextran-40 (6 dogs) was attempted. A solution of Evans Blue was also injected. After 2h of resuscitation the dogs were euthanised and their brains weighed and checked for Evans Blue staining under microscope. A control group of five dogs wasn’t bled or ballooned but normal saline and Evans Blue solution only.

Study design: Experimental controlled study.
Outcome Studied: Continuous ICP monitoring, blood brain barrier function assessed by degree of Evans Blue staining and cerebral oedema formation assessed by wet brain weights.

Main Findings
(relevant to PICO question):

3% hypertonic saline caused lower intracranial pressure and less cerebral oedema than either 0.9% saline or dextran-40, but blood brain barrier integrity is not restored.

Limitations:
  • experimental study
  • no survivors to assess clinical outcome
  • short term study of only 3h duration
  • small number of cases

Gunnar (1989)
Population: Laboratory Beagles
Sample size: 18
Intervention details: Hypovolaemic shock and closed head injury were simulated via bleeding of 40% of blood volume and epidurally inflated balloon. This was maintained for 1h, after that resuscitation with the shed blood and either 3% hypertonic saline, 0.9% saline or dextran-40 was attempted, after this, normal saline was given at a rate to maintain CVP at 10mmHg.

Study design: Experimental uncontrolled study.
Outcome Studied: Cerebral blood flow and ICP were measured at baseline, at the end of the shock period, during resuscitation and after resuscitation.
Main Findings
(relevant to PICO question):
Though the intracranial pressure was lower in the hypertonic saline group, cerebral blood flow did not vary.
Limitations:
  • experimental study
  • no assessment of clinical outcome
  • short term study of only 3h duration
  • small number of cases

Pinto (2006)
Population: Crossbreed dogs
Sample size: 15
Intervention details: 20 minutes after experimentally induced haemorrhagic shock via bleeding to MAP of 40mmHg and simulated traumatic brain injury via fluid percussion and epidural balloon, volume was replaced with 3% hypertonic saline (8ml/kg over 10 min) or LRS (16ml/kg over 10 ml) in five dogs each. 20 minutes later shed blood and more of the previous fluids were given to a haematocrit of 30% and a MAP of >70mm Hg. A control group of five received no fluids at either point. After 60 minutes the epidural balloon was deflated in the treatment groups.

Study design: Experimental, randomised, controlled study.

Outcome Studied: MAP, cardiac index, ICP, CPP, biochemistry and blood gases.
Main Findings
(relevant to PICO question):

3% hypertonic saline results in lower ICP than LRS even though CPP remains similar. Hypertonic saline also causes higher serum sodium concentration and osmolarity than LRS.

Limitations:
  • experimental study
  • no clinical outcome described
  • small number of cases

Sharma (2015)
Population: Client-owned dogs with head trauma <5 days before hospital admission.

Sample size: 72
Intervention details: No specific interventions, clinical records were analysed.
Study design: Retrospective descriptive study, based on medical records.
Outcome Studied: The prognostic value of clinical and laboratory variables, scoring systems and treatments (such as hypertonic saline) in dogs with head trauma was calculated.

Main Findings
(relevant to PICO question):

Hypertonic saline administration was associated with lower likelihood of survival to discharge (8 survivors, 4 nonsurvivors).

Limitations:
  • retrospective case study
  • no control group
  • multiple parameters observed, prognostic value of individual variables on their own hard to quantify
  • small number of cases

Pinto (2015)
Population: Crossbreed dogs
Sample size: 15
Intervention details: 20 minutes after experimentally induced haemorrhagic shock via bleeding to MAP of 40mmHg and simulated traumatic brain injury via fluid percussion and epidural balloon, volume was replaced with 3% hypertonic saline (8ml/kg over 10 min) or LRS (16ml/kg over 10 min) in 5 dogs each. 20 minutes later shed blood and more of the previous fluids were given to a haematocrit of 30% and a MAP of >70mm Hg. A control group of five dogs received no fluids at either point. After 1h the epidural balloon was deflated in the treatment groups. All dogs were euthanised after 3h and the brains removed, visually assessed and further analysed after tissue fixation.

Study design: Experimental controlled study.
Outcome Studied: MAP and ICP were measured, changes in pupil state were assessed every 10 minutes, macroscopic and microscopic brain pathology and prostaglandoid production were assessed.
Main Findings
(relevant to PICO question):
ICP was the lowest in the hypertonic saline cases during the initial 60 minutes. In brains that had received hypertonic saline, no cerebral oedema was identified macroscopically and ischaemic lesions were less evident. In cases with pupil changes, the pupils reversed to normal sooner in the hypertonic saline group.

Limitations:
  • experimental study
  • no survivors to assess clinical outcome
  • short term study of only 3h duration
  • macroscopic assessment for cerebral oedema only
  • small number of cases

Appraisal, application and reflection

The purpose of this Knowledge Summary was to look at the evidence for the use of hypertonic saline in reducing intracranial pressure in head trauma patients.

The experimental studies available in dogs seem to indicate that hypertonic saline might have a good effect on increased intracranial pressure after traumatic brain injury while achieving desirable haemodynamic parameters.

There are no controlled clinical studies that evaluate the use of hypertonic saline as an independent variable. In the descriptive study from Sharma & Holowaychuck (2015) the decision to use hypertonic saline was the clinician’s, and sometimes made after other treatment options had been unsuccessful. The choice to use hypertonic saline appears mostly to have been made in very severe cases, which may explain the negative predictive value of hypertonic saline use on survival until discharge.

In conclusion, hypertonic saline appears to be effective in reducing intracranial pressure after traumatic brain injury in experimental studies. How effective its use might be in clinical settings cannot be answered.

Methodology Section

Search Strategy
Databases searched and dates covered: PubMed database, accessed via the NCBI website (1910-2015) and the CAB abstracts database (1973-2015)
Search terms: (dog OR dogs OR canine OR puppy OR puppies OR canis) AND (((brain AND (trauma OR injur*)) OR (head AND (trauma OR injur*))) AND (hypertonic AND (saline OR sodium))
Dates searches performed:

18th July 2016

Exclusion / Inclusion Criteria
Exclusion: Articles not available in English or German, single case reports, book chapters and conference proceedings, articles which were not relevant to the question.
Inclusion: Articles available in English or German, which were relevant to the question.

Search Outcome

Database

Number of results

Excluded – language

Excluded – not relevant to question

Total relevant papers

CAB Abstracts

2 0 1 1

NCBI PubMed

15 0 9 6

Total relevant papers when duplicates removed

6


Conflict of Interest

The authors declare no conflicts of interest.


References

  1. Gunnar, W. et al. (1988) Head injury and hemorrhagic shock: studies of the blood brain barrier and intracranial pressure after resuscitation with normal saline solution, 3% saline solution, and dextran-40. Surgery, 103 (4), pp. 398–407.
  2. Gunnar, W. Kane, J. & Barrett, J. (1989) Cerebral blood flow following hypertonic saline resuscitation in an experimental model of hemorrhagic shock and head injury. Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas / Sociedade Brasileira de Biofisica ... [et al.], 22 (2), pp. 287–289.
  3. Pinto, F.C.G. et al. (2015) Effect of volume replacement during combined experimental hemorrhagic shock and traumatic brain injury in prostanoids, brain pathology and pupil status. Arquivos de neuro-psiquiatria, 73 (6), pp. 499–505. http://dx.doi.org/10.1590/0004-282X20150039
  4. Pinto, F.C.G. et al. (2006) Volume replacement with lactated Ringer's or 3% hypertonic saline solution during combined experimental hemorrhagic shock and traumatic brain injury. The Journal of trauma, 60(4), pp. 758–63– discussion 763–4. 10.1097/01.ta.0000214581.89316.73
  5. Prough, D.S. JOHNSON, J.C. & Poole, G.V.J. (1986) Effects on intracranial pressure of resuscitation from hemorrhagic shock with hypertonic saline versus lactated Ringer's solution. Journal of Trauma and Acute Care Surgery, 26 (1), p. 97.
  6. Sharma, D. & Holowaychuk, M.K. (2015) Retrospective evaluation of prognostic indicators in dogs with head trauma: 72 cases (January-March 2011). Journal of Veterinary Emergency and Critical Care, 25 (5), pp. 631–639. 10.1111/vec.12328

Intellectual Property Rights

Knowledge Summaries are a peer-reviewed article type which aims to answer a clinical question based on the best available current evidence. It does not override the responsibility of the practitioner. Informed decisions should be made by considering such factors as individual clinical expertise and judgement along with patient’s circumstances and owners’ values. Knowledge Summaries are a resource to help inform and any opinions expressed within the Knowledge Summaries are the author's own and do not necessarily reflect the view of the RCVS Knowledge.

Authors of Knowledge Summaries submitted to RCVS Knowledge for publication will retain copyright in their work, but will be required to grant to RCVS Knowledge an exclusive licence of the rights of copyright in the materials including but not limited to the right to publish, re-publish, transmit, sell, distribute and otherwise use the materials in all languages and all media throughout the world, and to licence or permit others to do so.

Authors will be required to complete a licence for publication form, and will in return retain certain rights as detailed on the form.



Open Access Peer Reviewed
Refbacks
  • There are currently no refbacks.


Copyright (c) 2017 Alex Tischer

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Made possible through a project grant from the RCVS Council.

RCVS