II. Cortical Spreading Depression
Intracortical spreading depression following local application of K+Cl-. The signal is spreading in a wave pattern at a speed of 3,5 mm/min over the whole Cortex (Vilagi, Klapka & Luhmann, 2001).
IV. Excitotoxicity
Energy depletion shuts down Glutamate-Portersystems and produces Lactacidosis.
Extracellular Glutamate concentration rises; Acidosis removes the Mg++-lock from the NMDA-Receptor (Ca-channel)
Intracellular Ca++-overload
„Misuse“ of Mitochondria
Further Energy depletion, Cell death
V. Lipid Peroxydation
•Oxygen free radicals [Reactive oxygen species (ROS)] attack the cell membrane and organelles
•Arachidonic acid is oxydized to eicosanoids plus further ROS
•Thromboxane disrupts the blood-brain- barrier, producing vasogenic oedema
•Excess Calcium binds to phosphate, limiting phosphorylation of ADP to ATP
Results of „Dysventilation“
•Hypoxia: Brain damage
•Hyperoxia: Convulsions
•Hypocapnia: Cerebral ischaemia
•Hypercapnia: Brain swelling (venous
congestion resulting in intracranial hypertension)
CO2-Reactivity of cerebral vessels: Effects of paCO2 [ETpCO2] on ICP
Removing / reintegrating soda lime absorbers of the breathing system.
Culprit vs. Victim: Specific
(1)
Brain Lung: Traumatic Brain Injury (TBI)
TBI Neurogenic Pulmonary Oedema
•Frequency: 50%
•Mechanism: Catecholamine surge
TBI Acute Lung Injury (ALI)
• Frequency: 30%
J Trauma (2003) 55:106-11
Culprit vs. Victim: Specific
(2)
Brain Lung: Subarachnoid Haemorrhage
(SAH)
SAH Neurogenic Pulmonary Oedema
•Frequency: 25%
•Mechanism: Catecholamine surge
SAH ARDS
• Frequency: 20%
Intensive Care Med (2002) 28:1012-23
How does the Lung damage the
Brain ?
•Pulmonary liberation of Cytokines Brain
•Pneumonia Sepsis Septic Encephalopathy
•Pneumonia Fever Cerebral Hyperthermia Excitotoxicity
•ARDS Pulmonary compliance AWP ICP
•ARDS Permissive Hypercapnia ICP
Brain atrophy and cognitive impairment of ARDS
Sharshar et al. 2007
Intensive Care Med 33 798-806
(Brain lesions in septic shock: a MRI study) Hopkins et al. 2006 Brain Injury 20 263-271
Effects of varying levels of positive end-expiratory pressure on intracranial pressure and cerebral perfusion pressure
McGuire et al. Crit Care Med 1997