OVERVIEW
- A ‘volume-targeted’ approach to the management of TBI developed by a Swedish group (not ABBA)
- based on physiological volume regulation of the intracranial compartments
- The Lund concept contradicts the prevailing strategem of titrating CPP to match ICP in TBI
THEORY
Normal healthy brain
- The balance between effective transcapillary hydrostatic and osmotic pressures constitutes the driving force for transcapillary fluid exchange
- The low permeability for sodium and chloride combined with the high crystalloid osmotic pressure (approximately 5700 mmHg) on both sides of the blood-brain barrier (BBB) counteracts fluid exchange across the intact BBB
- variations in systemic BP generally are not transmitted to these capillaries because cerebral intracapillary hydrostatic pressure (and blood flow) is tightly autoregulated
In TBI
- the BBB may be partially disrupted
- transcapillary water exchange is determined by the differences in hydrostatic and colloid osmotic pressure between the intra- and extracapillary compartments
- pressure autoregulation of cerebral blood flow is likely to be impaired in these conditions
- a high cerebral perfusion pressure increases intracapillary hydrostatic pressure and leads to increased intracerebral water content and an increase in ICP
MANAGEMNT ACCORDING TO THE LUND CONCEPT
Principles
- The prevention of brain oedema formation to reduce fluid shift from capillaries into brain parenchyma, by preserving capillary colloid osmotic pressure and reducing capillary hydrostatic pressure
- The improvement of the cerebral microcirculation by the avoidance of arterial vasoconstrictors
Preserve osmotic pressure
- albumin (considered a contra-indication by some based on SAFE trial subgroup analysis)
- blood products
- diuretics
Reduce hydrostatic pressure
- metoprolol
- clonidine
- thiopentone
- dihydroergotamine (precapillary vasoconstriction)
CPP target
- if ICP normal aim for 60-70mmHg
- however, if ICP elevated a CPP of 50mmHg is accepted
Vasoactive use
- avoid dobutamine (cerebral vasodilatation)
- avoid noradrenaline (cerebral vasoconstriction)
EVIDENCE
- improved outcomes compared with historical controls and other institutions have been reported in a few nonrandomized studies
- until recently had never been subjected to a randomized trial and had never been evaluated outside Sweden
- one small Bosnian RCT found a mortality benefit for a ‘modified Lund protocol’ in TBI, compared to a CPP targetted approach
- good evidence against some components of the Lund concept protocol
References and Links
- Dizdarevic K, Hamdan A, Omerhodzic I, Kominlija-Smajic E. Modified Lund concept versus cerebral perfusion pressure-targeted therapy: a randomised controlled study in patients with secondary brain ischaemia. Clin Neurol Neurosurg. 2012 Feb;114(2):142-8. doi: 10.1016/j.clineuro.2011.10.005. Epub 2011 Oct 28. PubMed PMID: 22036839.
- Grände PO. The Lund concept for the treatment of patients with severe traumatic brain injury. J Neurosurg Anesthesiol. 2011 Oct;23(4):358-62. doi: 10.1097/01.ana.0000405612.20356.84. Review. PubMed PMID: 21908989.
- Nordström CH. Physiological and biochemical principles underlying volume-targeted therapy–the “Lund concept”. Neurocrit Care. 2005;2(1):83-95. Review. PubMed PMID: 16174975.
- Sharma D, Vavilala MS. Lund concept for the management of traumatic brain injury: a physiological principle awaiting stronger evidence. J Neurosurg Anesthesiol. 2011 Oct;23(4):363-7. doi: 10.1097/01.ana.0000405613.27980.ea. Review. PubMed PMID: 21908990.
Grande Lund Concept
http://www.ncbi.nlm.nih.gov/pubmed/16896859
Interview with Grande
http://www.intensive.org/ISICEM_News/Traumatic%20brain%20injury.pdf